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localbuf: Add Valgrind buffer access instrumentation

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This mirrors 1e0dfd166b3 (+ 46ef520b9566), for temporary table buffers. This
is mainly interesting right now because the AIO work currently triggers
spurious valgrind errors, and the fix for that is cleaner if temp buffers
behave the same as shared buffers.

This requires one change beyond the annotations themselves, namely to pin
local buffers while writing them out in FlushRelationBuffers().

Reviewed-by: Noah Misch <noah@leadboat.com>
Co-authored-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/3pd4322mogfmdd5nln3zphdwhtmq3rzdldqjwb2sfqzcgs22lf@ok2gletdaoe6
This commit is contained in:
Andres Freund 2025-04-07 15:20:30 -04:00
parent a13d49014d
commit 8ab4241b9f
2 changed files with 38 additions and 0 deletions
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13
src/backend/storage/buffer/bufmgr.c
View File

@ -4895,8 +4895,21 @@ FlushRelationBuffers(Relation rel)
errcallback.previous = error_context_stack;
error_context_stack = &errcallback;
/* Make sure we can handle the pin */
ReservePrivateRefCountEntry();
ResourceOwnerEnlarge(CurrentResourceOwner);
/*
* Pin/upin mostly to make valgrind work, but it also seems
* like the right thing to do.
*/
PinLocalBuffer(bufHdr, false);
FlushLocalBuffer(bufHdr, srel);
UnpinLocalBuffer(BufferDescriptorGetBuffer(bufHdr));
/* Pop the error context stack */
error_context_stack = errcallback.previous;
}

25
src/backend/storage/buffer/localbuf.c
View File

@ -23,6 +23,7 @@
#include "storage/bufmgr.h"
#include "storage/fd.h"
#include "utils/guc_hooks.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
#include "utils/resowner.h"
@ -183,6 +184,8 @@ FlushLocalBuffer(BufferDesc *bufHdr, SMgrRelation reln)
instr_time io_start;
Page localpage = (char *) LocalBufHdrGetBlock(bufHdr);
Assert(LocalRefCount[-BufferDescriptorGetBuffer(bufHdr) - 1] > 0);
/*
* Try to start an I/O operation. There currently are no reasons for
* StartLocalBufferIO to return false, so we raise an error in that case.
@ -808,6 +811,15 @@ PinLocalBuffer(BufferDesc *buf_hdr, bool adjust_usagecount)
buf_state += BUF_USAGECOUNT_ONE;
}
pg_atomic_unlocked_write_u32(&buf_hdr->state, buf_state);
/*
* See comment in PinBuffer().
*
* If the buffer isn't allocated yet, it'll be marked as defined in
* GetLocalBufferStorage().
*/
if (LocalBufHdrGetBlock(buf_hdr) != NULL)
VALGRIND_MAKE_MEM_DEFINED(LocalBufHdrGetBlock(buf_hdr), BLCKSZ);
}
LocalRefCount[bufid]++;
ResourceOwnerRememberBuffer(CurrentResourceOwner,
@ -843,6 +855,9 @@ UnpinLocalBufferNoOwner(Buffer buffer)
Assert(BUF_STATE_GET_REFCOUNT(buf_state) > 0);
buf_state -= BUF_REFCOUNT_ONE;
pg_atomic_unlocked_write_u32(&buf_hdr->state, buf_state);
/* see comment in UnpinBufferNoOwner */
VALGRIND_MAKE_MEM_NOACCESS(LocalBufHdrGetBlock(buf_hdr), BLCKSZ);
}
}
@ -923,6 +938,16 @@ GetLocalBufferStorage(void)
next_buf_in_block++;
total_bufs_allocated++;
/*
* Caller's PinLocalBuffer() was too early for Valgrind updates, so do it
* here. The block is actually undefined, but we want consistency with
* the regular case of not needing to allocate memory. This is
* specifically needed when method_io_uring.c fills the block, because
* Valgrind doesn't recognize io_uring reads causing undefined memory to
* become defined.
*/
VALGRIND_MAKE_MEM_DEFINED(this_buf, BLCKSZ);
return (Block) this_buf;
}