diff options
| author | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2015-05-13 09:44:43 +0300 |
|---|---|---|
| committer | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2015-05-13 10:06:47 +0300 |
| commit | f6c4a8690c9374be828c7fca4c2b6199f39b27fa (patch) | |
| tree | 03405cf9f77f6b9a65751c8468427aa67fde93d1 /src/backend/storage/buffer/bufmgr.c | |
| parent | dd75518d523a1e3650b5d5ad20c755a000425739 (diff) | |
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.
Diffstat (limited to 'src/backend/storage/buffer/bufmgr.c')
| -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 c4e8c4a9972..6ef8c247547 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -494,7 +494,8 @@ 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) |