From: Tomas Vondra <tomas.vondra@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Silence valgrind about pg_numa_touch_mem_if_required
Date: Tue, 01 Jul 2025 10:34:29 +0000
Message-ID: <E1uWYJp-004Aqu-2a@gemulon.postgresql.org> (raw)
Silence valgrind about pg_numa_touch_mem_if_required
When querying NUMA status of pages in shared memory, we need to touch
the memory first to get valid results. This may trigger valgrind
reports, because some of the memory (e.g. unpinned buffers) may be
marked as noaccess.
Solved by adding a valgrind suppresion. An alternative would be to
adjust the access/noaccess status before touching the memory, but that
seems far too invasive. It would require all those places to have
detailed knowledge of what the shared memory stores.
The pg_numa_touch_mem_if_required() macro is replaced with a function.
Macros are invisible to suppressions, so it'd have to suppress reports
for the caller - e.g. pg_get_shmem_allocations_numa(). So we'd suppress
reports for the whole function, and that seems to heavy-handed. It might
easily hide other valid issues.
Reviewed-by: Christoph Berg <myon@debian.org>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/aEtDozLmtZddARdB@msg.df7cb.de
Backpatch-through: 18
Branch
------
REL_18_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/14e52227e57885d1a983d9f2515b569d3180c93d
Modified Files
--------------
contrib/pg_buffercache/pg_buffercache_pages.c | 3 +--
src/backend/storage/ipc/shmem.c | 4 +---
src/include/port/pg_numa.h | 10 +++++++---
src/tools/valgrind.supp | 14 ++++++++++++++
4 files changed, 23 insertions(+), 8 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: tomas.vondra@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Silence valgrind about pg_numa_touch_mem_if_required
In-Reply-To: <E1uWYJp-004Aqu-2a@gemulon.postgresql.org>
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