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pgsql: Fix concurrency issues with DROP TABLESPACE 7+ messages / 1 participants [nested] [flat]
* pgsql: Fix concurrency issues with DROP TABLESPACE @ 2026-09-09 15:34 Andrew Dunstan <andrew@dunslane.net> 0 siblings, 0 replies; 7+ messages in thread From: Andrew Dunstan @ 2026-09-09 15:34 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix concurrency issues with DROP TABLESPACE DROP TABLESPACE checked pg_shdepend for dependent objects without first locking the tablespace. A concurrent command that recorded a shared dependency on the tablespace right after that check could still commit, leaving an object whose pg_shdepend entry (or, for a relation, pg_class.reltablespace) pointed to a tablespace that no longer existed. Close the race by having DropTableSpace() take an AccessExclusiveLock on the tablespace before calling checkSharedDependencies(). That conflicts with the AccessShareLock shdepLockAndCheckObject() takes when recording a new dependency, so the loser of the race blocks and rechecks once the winner commits. That AccessExclusiveLock creates a new deadlock: ALTER TABLESPACE RENAME/SET and the internal ACL/owner updates in DROP OWNED and REASSIGN OWNED touched the catalog tuple without locking the tablespace, risking a lock-order cycle with DROP. Fix by taking an AccessShareLock first in all four paths, rechecking pg_shdepend after any wait in the DROP OWNED and REASSIGN OWNED cases. GRANT, REVOKE, and ALTER TABLESPACE ... OWNER TO already lock the object. Add isolation tests covering both orderings of the original race (dependency-first and drop-first) and all four previously-unlocked update paths. Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com> Reviewed-by: Andrew Dunstan <andrew@dunslane.net> Discussion: https://postgr.es/m/CAJTYsWXjAQFnGKzXsht3XK8KHhyhontwFJw4JAHsUSfs_ptR4g@mail.gmail.com Backpatch-through: 14 Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/a12600b762c36d91450ce085fa25ef75250bc1c2 Modified Files -------------- src/backend/catalog/pg_shdepend.c | 40 +++++++-- src/backend/commands/tablespace.c | 16 +++- .../expected/tablespace-dependency-locking.out | 84 +++++++++++++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/tablespace-dependency-locking.spec | 98 ++++++++++++++++++++++ 5 files changed, 232 insertions(+), 7 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix concurrency issues with DROP TABLESPACE @ 2026-09-09 15:34 Andrew Dunstan <andrew@dunslane.net> 0 siblings, 0 replies; 7+ messages in thread From: Andrew Dunstan @ 2026-09-09 15:34 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix concurrency issues with DROP TABLESPACE DROP TABLESPACE checked pg_shdepend for dependent objects without first locking the tablespace. A concurrent command that recorded a shared dependency on the tablespace right after that check could still commit, leaving an object whose pg_shdepend entry (or, for a relation, pg_class.reltablespace) pointed to a tablespace that no longer existed. Close the race by having DropTableSpace() take an AccessExclusiveLock on the tablespace before calling checkSharedDependencies(). That conflicts with the AccessShareLock shdepLockAndCheckObject() takes when recording a new dependency, so the loser of the race blocks and rechecks once the winner commits. That AccessExclusiveLock creates a new deadlock: ALTER TABLESPACE RENAME/SET and the internal ACL/owner updates in DROP OWNED and REASSIGN OWNED touched the catalog tuple without locking the tablespace, risking a lock-order cycle with DROP. Fix by taking an AccessShareLock first in all four paths, rechecking pg_shdepend after any wait in the DROP OWNED and REASSIGN OWNED cases. GRANT, REVOKE, and ALTER TABLESPACE ... OWNER TO already lock the object. Add isolation tests covering both orderings of the original race (dependency-first and drop-first) and all four previously-unlocked update paths. Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com> Reviewed-by: Andrew Dunstan <andrew@dunslane.net> Discussion: https://postgr.es/m/CAJTYsWXjAQFnGKzXsht3XK8KHhyhontwFJw4JAHsUSfs_ptR4g@mail.gmail.com Backpatch-through: 14 Branch ------ REL_19_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/5dec175fb4c537947faaba504cda394b4ca6b726 Modified Files -------------- src/backend/catalog/pg_shdepend.c | 40 +++++++-- src/backend/commands/tablespace.c | 16 +++- .../expected/tablespace-dependency-locking.out | 84 +++++++++++++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/tablespace-dependency-locking.spec | 98 ++++++++++++++++++++++ 5 files changed, 232 insertions(+), 7 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix concurrency issues with DROP TABLESPACE @ 2026-09-09 15:34 Andrew Dunstan <andrew@dunslane.net> 0 siblings, 0 replies; 7+ messages in thread From: Andrew Dunstan @ 2026-09-09 15:34 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix concurrency issues with DROP TABLESPACE DROP TABLESPACE checked pg_shdepend for dependent objects without first locking the tablespace. A concurrent command that recorded a shared dependency on the tablespace right after that check could still commit, leaving an object whose pg_shdepend entry (or, for a relation, pg_class.reltablespace) pointed to a tablespace that no longer existed. Close the race by having DropTableSpace() take an AccessExclusiveLock on the tablespace before calling checkSharedDependencies(). That conflicts with the AccessShareLock shdepLockAndCheckObject() takes when recording a new dependency, so the loser of the race blocks and rechecks once the winner commits. That AccessExclusiveLock creates a new deadlock: ALTER TABLESPACE RENAME/SET and the internal ACL/owner updates in DROP OWNED and REASSIGN OWNED touched the catalog tuple without locking the tablespace, risking a lock-order cycle with DROP. Fix by taking an AccessShareLock first in all four paths, rechecking pg_shdepend after any wait in the DROP OWNED and REASSIGN OWNED cases. GRANT, REVOKE, and ALTER TABLESPACE ... OWNER TO already lock the object. Add isolation tests covering both orderings of the original race (dependency-first and drop-first) and all four previously-unlocked update paths. Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com> Reviewed-by: Andrew Dunstan <andrew@dunslane.net> Discussion: https://postgr.es/m/CAJTYsWXjAQFnGKzXsht3XK8KHhyhontwFJw4JAHsUSfs_ptR4g@mail.gmail.com Backpatch-through: 14 Branch ------ REL_18_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/d77627daac5baa895a1d37d2d12666bbf55585a5 Modified Files -------------- src/backend/catalog/pg_shdepend.c | 40 +++++++-- src/backend/commands/tablespace.c | 18 +++- .../expected/tablespace-dependency-locking.out | 84 +++++++++++++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/tablespace-dependency-locking.spec | 98 ++++++++++++++++++++++ 5 files changed, 234 insertions(+), 7 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix concurrency issues with DROP TABLESPACE @ 2026-09-09 15:34 Andrew Dunstan <andrew@dunslane.net> 0 siblings, 0 replies; 7+ messages in thread From: Andrew Dunstan @ 2026-09-09 15:34 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix concurrency issues with DROP TABLESPACE DROP TABLESPACE checked pg_shdepend for dependent objects without first locking the tablespace. A concurrent command that recorded a shared dependency on the tablespace right after that check could still commit, leaving an object whose pg_shdepend entry (or, for a relation, pg_class.reltablespace) pointed to a tablespace that no longer existed. Close the race by having DropTableSpace() take an AccessExclusiveLock on the tablespace before calling checkSharedDependencies(). That conflicts with the AccessShareLock shdepLockAndCheckObject() takes when recording a new dependency, so the loser of the race blocks and rechecks once the winner commits. That AccessExclusiveLock creates a new deadlock: ALTER TABLESPACE RENAME/SET and the internal ACL/owner updates in DROP OWNED and REASSIGN OWNED touched the catalog tuple without locking the tablespace, risking a lock-order cycle with DROP. Fix by taking an AccessShareLock first in all four paths, rechecking pg_shdepend after any wait in the DROP OWNED and REASSIGN OWNED cases. GRANT, REVOKE, and ALTER TABLESPACE ... OWNER TO already lock the object. Add isolation tests covering both orderings of the original race (dependency-first and drop-first) and all four previously-unlocked update paths. Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com> Reviewed-by: Andrew Dunstan <andrew@dunslane.net> Discussion: https://postgr.es/m/CAJTYsWXjAQFnGKzXsht3XK8KHhyhontwFJw4JAHsUSfs_ptR4g@mail.gmail.com Backpatch-through: 14 Branch ------ REL_17_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/960b6b53241e41ec4c0e960b23c718c8aaba076b Modified Files -------------- src/backend/catalog/pg_shdepend.c | 40 +++++++-- src/backend/commands/tablespace.c | 18 +++- .../expected/tablespace-dependency-locking.out | 84 +++++++++++++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/tablespace-dependency-locking.spec | 98 ++++++++++++++++++++++ 5 files changed, 234 insertions(+), 7 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix concurrency issues with DROP TABLESPACE @ 2026-09-09 15:34 Andrew Dunstan <andrew@dunslane.net> 0 siblings, 0 replies; 7+ messages in thread From: Andrew Dunstan @ 2026-09-09 15:34 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix concurrency issues with DROP TABLESPACE DROP TABLESPACE checked pg_shdepend for dependent objects without first locking the tablespace. A concurrent command that recorded a shared dependency on the tablespace right after that check could still commit, leaving an object whose pg_shdepend entry (or, for a relation, pg_class.reltablespace) pointed to a tablespace that no longer existed. Close the race by having DropTableSpace() take an AccessExclusiveLock on the tablespace before calling checkSharedDependencies(). That conflicts with the AccessShareLock shdepLockAndCheckObject() takes when recording a new dependency, so the loser of the race blocks and rechecks once the winner commits. That AccessExclusiveLock creates a new deadlock: ALTER TABLESPACE RENAME/SET and the internal ACL/owner updates in DROP OWNED and REASSIGN OWNED touched the catalog tuple without locking the tablespace, risking a lock-order cycle with DROP. Fix by taking an AccessShareLock first in all four paths, rechecking pg_shdepend after any wait in the DROP OWNED and REASSIGN OWNED cases. GRANT, REVOKE, and ALTER TABLESPACE ... OWNER TO already lock the object. Add isolation tests covering both orderings of the original race (dependency-first and drop-first) and all four previously-unlocked update paths. Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com> Reviewed-by: Andrew Dunstan <andrew@dunslane.net> Discussion: https://postgr.es/m/CAJTYsWXjAQFnGKzXsht3XK8KHhyhontwFJw4JAHsUSfs_ptR4g@mail.gmail.com Backpatch-through: 14 Branch ------ REL_16_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/749dd8d1f2cf8ae261122b8db397bc5dafcb99bb Modified Files -------------- src/backend/catalog/pg_shdepend.c | 42 ++++++++-- src/backend/commands/tablespace.c | 17 +++- .../expected/tablespace-dependency-locking.out | 84 +++++++++++++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/tablespace-dependency-locking.spec | 98 ++++++++++++++++++++++ 5 files changed, 235 insertions(+), 7 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix concurrency issues with DROP TABLESPACE @ 2026-09-09 15:34 Andrew Dunstan <andrew@dunslane.net> 0 siblings, 0 replies; 7+ messages in thread From: Andrew Dunstan @ 2026-09-09 15:34 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix concurrency issues with DROP TABLESPACE DROP TABLESPACE checked pg_shdepend for dependent objects without first locking the tablespace. A concurrent command that recorded a shared dependency on the tablespace right after that check could still commit, leaving an object whose pg_shdepend entry (or, for a relation, pg_class.reltablespace) pointed to a tablespace that no longer existed. Close the race by having DropTableSpace() take an AccessExclusiveLock on the tablespace before calling checkSharedDependencies(). That conflicts with the AccessShareLock shdepLockAndCheckObject() takes when recording a new dependency, so the loser of the race blocks and rechecks once the winner commits. That AccessExclusiveLock creates a new deadlock: ALTER TABLESPACE RENAME/SET and the internal ACL/owner updates in DROP OWNED and REASSIGN OWNED touched the catalog tuple without locking the tablespace, risking a lock-order cycle with DROP. Fix by taking an AccessShareLock first in all four paths, rechecking pg_shdepend after any wait in the DROP OWNED and REASSIGN OWNED cases. GRANT, REVOKE, and ALTER TABLESPACE ... OWNER TO already lock the object. Add isolation tests covering both orderings of the original race (dependency-first and drop-first) and all four previously-unlocked update paths. Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com> Reviewed-by: Andrew Dunstan <andrew@dunslane.net> Discussion: https://postgr.es/m/CAJTYsWXjAQFnGKzXsht3XK8KHhyhontwFJw4JAHsUSfs_ptR4g@mail.gmail.com Backpatch-through: 14 Branch ------ REL_15_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/00126dedef74dc8588938328d162771800a98fcb Modified Files -------------- src/backend/catalog/pg_shdepend.c | 46 ++++++++-- src/backend/commands/tablespace.c | 17 +++- .../expected/tablespace-dependency-locking.out | 84 +++++++++++++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/tablespace-dependency-locking.spec | 98 ++++++++++++++++++++++ 5 files changed, 239 insertions(+), 7 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
* pgsql: Fix concurrency issues with DROP TABLESPACE @ 2026-09-09 15:34 Andrew Dunstan <andrew@dunslane.net> 0 siblings, 0 replies; 7+ messages in thread From: Andrew Dunstan @ 2026-09-09 15:34 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Fix concurrency issues with DROP TABLESPACE DROP TABLESPACE checked pg_shdepend for dependent objects without first locking the tablespace. A concurrent command that recorded a shared dependency on the tablespace right after that check could still commit, leaving an object whose pg_shdepend entry (or, for a relation, pg_class.reltablespace) pointed to a tablespace that no longer existed. Close the race by having DropTableSpace() take an AccessExclusiveLock on the tablespace before calling checkSharedDependencies(). That conflicts with the AccessShareLock shdepLockAndCheckObject() takes when recording a new dependency, so the loser of the race blocks and rechecks once the winner commits. That AccessExclusiveLock creates a new deadlock: ALTER TABLESPACE RENAME/SET and the internal ACL/owner updates in DROP OWNED and REASSIGN OWNED touched the catalog tuple without locking the tablespace, risking a lock-order cycle with DROP. Fix by taking an AccessShareLock first in all four paths, rechecking pg_shdepend after any wait in the DROP OWNED and REASSIGN OWNED cases. GRANT, REVOKE, and ALTER TABLESPACE ... OWNER TO already lock the object. Add isolation tests covering both orderings of the original race (dependency-first and drop-first) and all four previously-unlocked update paths. Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com> Reviewed-by: Andrew Dunstan <andrew@dunslane.net> Discussion: https://postgr.es/m/CAJTYsWXjAQFnGKzXsht3XK8KHhyhontwFJw4JAHsUSfs_ptR4g@mail.gmail.com Backpatch-through: 14 Branch ------ REL_14_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/539b7e8290e71a253ac4b70faed75e38a7125d97 Modified Files -------------- src/backend/catalog/pg_shdepend.c | 46 ++++++++-- src/backend/commands/tablespace.c | 17 +++- .../expected/tablespace-dependency-locking.out | 84 +++++++++++++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/tablespace-dependency-locking.spec | 98 ++++++++++++++++++++++ 5 files changed, 239 insertions(+), 7 deletions(-) ^ permalink raw reply [nested|flat] 7+ messages in thread
end of thread, other threads:[~2026-09-09 15:34 UTC | newest] Thread overview: 7+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2026-09-09 15:34 pgsql: Fix concurrency issues with DROP TABLESPACE Andrew Dunstan <andrew@dunslane.net> 2026-09-09 15:34 pgsql: Fix concurrency issues with DROP TABLESPACE Andrew Dunstan <andrew@dunslane.net> 2026-09-09 15:34 pgsql: Fix concurrency issues with DROP TABLESPACE Andrew Dunstan <andrew@dunslane.net> 2026-09-09 15:34 pgsql: Fix concurrency issues with DROP TABLESPACE Andrew Dunstan <andrew@dunslane.net> 2026-09-09 15:34 pgsql: Fix concurrency issues with DROP TABLESPACE Andrew Dunstan <andrew@dunslane.net> 2026-09-09 15:34 pgsql: Fix concurrency issues with DROP TABLESPACE Andrew Dunstan <andrew@dunslane.net> 2026-09-09 15:34 pgsql: Fix concurrency issues with DROP TABLESPACE Andrew Dunstan <andrew@dunslane.net>
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