localbuf: Add Valgrind buffer access instrumentation

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 <[email protected]>
Co-authored-by: Noah Misch <[email protected]>
Discussion: https://postgr.es/m/3pd4322mogfmdd5nln3zphdwhtmq3rzdldqjwb2sfqzcgs22lf@ok2gletdaoe6

2 files changed, 38 insertions, 0 deletions

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index ffaca5ee54d..5da121872f4 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -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;
 			}
diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c
index ed56202af14..63101d56a07 100644
--- a/src/backend/storage/buffer/localbuf.c
+++ b/src/backend/storage/buffer/localbuf.c
@@ -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;
 }