Horton

Re: Reducing the chunk header sizes on all memory context types

David Rowley <dgrowleyml@gmail.com>

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From: David Rowley <dgrowleyml@gmail.com>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Amit Kapila <amit.kapila16@gmail.com>, Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2022-08-30T01:16:00Z
Lists: pgsql-hackers

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On Tue, 30 Aug 2022 at 12:45, David Rowley <dgrowleyml@gmail.com> wrote:
> I think the existing sentinel check looks wrong:
>
> if (!sentinel_ok(chunk, slab->chunkSize))
>
> shouldn't that be passing the pointer rather than the chunk?

Here's v2 of the slab-fix patch.

I've included the sentinel check fix.  This passes make check-world
for me when do a 32-bit build on my x86_64 machine and adjust
pg_config.h to set MAXIMUM_ALIGNOF to 8.

Any chance you could run make check-world on your 32-bit Raspberry PI?

I'm also wondering if this should also be backpatched back to v10,
providing the build farm likes it well enough on master.

Commits

  1. Harden memory context allocators against bogus chunk pointers.

  2. Improve our ability to detect bogus pointers passed to pfree et al.

  3. Remove MemoryContextContains().

  4. Remove uses of MemoryContextContains in nodeAgg.c and nodeWindowAgg.c.

  5. Temporarily make MemoryContextContains return false

  6. Make MemoryContextContains work correctly again

  7. Make more effort to put a sentinel at the end of allocated memory

  8. Fix some possibly latent bugs in slab.c

  9. Various cleanups of the new memory context header code

  10. Revert "Add missing padding from MemoryChunk struct"

  11. Use MAXALIGN() in calculations using sizeof(SlabBlock)

  12. Add missing padding from MemoryChunk struct

  13. Improve performance of and reduce overheads of memory management