From 83eb54001cb69d6ee8f0813c4e280be876823068 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Wed, 23 Oct 2013 14:03:54 +0300 Subject: [PATCH] Fix two bugs in setting the vm bit of empty pages. Use a critical section when setting the all-visible flag on an empty page, and WAL-logging it. log_newpage_buffer() contains an assertion that it must be called inside a critical section, and it's the right thing to do when modifying a buffer anyway. Also, the page should be marked dirty before calling log_newpage_buffer(), per the comment in log_newpage_buffer() and src/backend/access/transam/README. Patch by Andres Freund, in response to my report. Backpatch to 9.2, like the patch that introduced these bugs (a6370fd9). --- src/backend/commands/vacuumlazy.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c index a6d5fc5932..e1d6d1c9e6 100644 --- a/src/backend/commands/vacuumlazy.c +++ b/src/backend/commands/vacuumlazy.c @@ -663,6 +663,11 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats, /* empty pages are always all-visible */ if (!PageIsAllVisible(page)) { + START_CRIT_SECTION(); + + /* mark buffer dirty before writing a WAL record */ + MarkBufferDirty(buf); + /* * It's possible that another backend has extended the heap, * initialized the page, and then failed to WAL-log the page @@ -682,9 +687,9 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats, log_newpage_buffer(buf); PageSetAllVisible(page); - MarkBufferDirty(buf); visibilitymap_set(onerel, blkno, buf, InvalidXLogRecPtr, vmbuffer, InvalidTransactionId); + END_CRIT_SECTION(); } UnlockReleaseBuffer(buf);