Fix bug in generation.c's valgrind support.

tglsfdc · tglsfdc · commit cc3c4af4a948 · 2017-11-24T13:43:34.000-05:00
This doesn't look like the last such bug, but it's one that the test_decoding regression test is tripping over. Per buildfarm. Tomas Vondra Discussion: https://postgr.es/m/c903f275-2150-fa52-64bf-dca7b53ebf8d@fuzzy.cz
diff --git a/src/backend/utils/mmgr/generation.c b/src/backend/utils/mmgr/generation.c
@@ -409,9 +409,14 @@ GenerationAlloc(MemoryContext context, Size size)
 
 	chunk = (GenerationChunk *) block->freeptr;
 
+	/* Prepare to initialize the chunk header. */
+	VALGRIND_MAKE_MEM_UNDEFINED(chunk, Generation_CHUNKHDRSZ);
+
 	block->nchunks += 1;
 	block->freeptr += (Generation_CHUNKHDRSZ + chunk_size);
 
+	Assert(block->freeptr <= block->endptr);
+
 	chunk->block = block;
 
 	chunk->context = set;
