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| author | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2015-05-13 09:44:43 +0300 |
|---|---|---|
| committer | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2015-05-13 09:53:50 +0300 |
| commit | 462a2f1f019fa16087fe2f59e96e339a703923b2 (patch) | |
| tree | a20150bc9308e86c2a56e551b814d5811e2dcdf9 | |
| parent | 4d3d9719d28ff9956540c36a05a4846b55b0234b (diff) | |
| download | postgresql-462a2f1f019fa16087fe2f59e96e339a703923b2.tar.gz postgresql-462a2f1f019fa16087fe2f59e96e339a703923b2.zip | |
Fix RBM_ZERO_AND_LOCK mode to not acquire lock on local buffers.
Commit 81c45081 introduced a new RBM_ZERO_AND_LOCK mode to ReadBuffer, which
takes a lock on the buffer before zeroing it. However, you cannot take a
lock on a local buffer, and you got a segfault instead. The version of that
patch committed to master included a check for !isLocalBuf, and therefore
didn't crash, but oddly I missed that in the back-patched versions. This
patch adds that check to the back-branches too.
RBM_ZERO_AND_LOCK mode is only used during WAL replay, and in hash indexes.
WAL replay only deals with shared buffers, so the only way to trigger the
bug is with a temporary hash index.
Reported by Artem Ignatyev, analysis by Tom Lane.
| -rw-r--r-- | src/backend/storage/buffer/bufmgr.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 2f753e52dbb..19ec7eb231e 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -515,7 +515,8 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum, * (Note that we cannot use LockBuffer() of LockBufferForCleanup() here, * because they assert that the buffer is already valid.) */ - if (mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK) + if ((mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK) && + !isLocalBuf) LWLockAcquire(bufHdr->content_lock, LW_EXCLUSIVE); if (isLocalBuf) |