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[PATCH v5 10/10] Additional validation for buffer in the ring 106+ messages / 1 participants [nested] [flat]
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
* [PATCH v5 10/10] Additional validation for buffer in the ring @ 2025-06-11 12:45 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 0 siblings, 0 replies; 106+ messages in thread From: Ashutosh Bapat @ 2025-06-11 12:45 UTC (permalink / raw) If the buffer pool has been shrunk, the buffers in the buffer list may not be valid anymore. Modify GetBufferFromRing to check if the buffer is still valid before using it. This makes GetBufferFromRing() a bit more expensive because of additional boolean condition. That may not be expensive enough to affect query performance. The alternative to that is more complex as explained below. The strategy object is created in CurrentMemoryContext and is not available in any global structure thus accessible when processing buffer resizing barriers. We may modify GetAccessStrategy() to register strategy in a global linked list and then arrange to deregister it once it's no more in use. Looking at the places which use GetAccessStrategy(), fixing all those may be some work. Ashutosh Bapat --- src/backend/storage/buffer/freelist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 41641bb3ae6..74d070733a4 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -948,12 +948,13 @@ GetBufferFromRing(BufferAccessStrategy strategy, uint32 *buf_state) strategy->current = 0; /* - * If the slot hasn't been filled yet, tell the caller to allocate a new - * buffer with the normal allocation strategy. He will then fill this - * slot by calling AddBufferToRing with the new buffer. + * If the slot hasn't been filled yet or the buffer in the slot has been + * invalidated when buffer pool was shrunk, tell the caller to allocate a new + * buffer with the normal allocation strategy. He will then fill this slot + * by calling AddBufferToRing with the new buffer. */ bufnum = strategy->buffers[strategy->current]; - if (bufnum == InvalidBuffer) + if (bufnum == InvalidBuffer || bufnum > NBuffers) return NULL; /* -- 2.49.0 --bwrlgp6w2ubxykjq-- ^ permalink raw reply [nested|flat] 106+ messages in thread
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buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> 2025-06-11 12:45 [PATCH v5 10/10] Additional validation for buffer in the ring Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
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