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author | Darrick J. Wong <darrick.wong@oracle.com> | 2017-01-25 20:24:57 -0800 |
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committer | Darrick J. Wong <darrick.wong@oracle.com> | 2017-01-25 20:24:57 -0800 |
commit | 2aa6ba7b5ad3189cc27f14540aa2f57f0ed8df4b (patch) | |
tree | c0974c14d598d72615b4e46f2ecb0e020d24efd0 /fs/xfs/xfs_buf.c | |
parent | 493611ebd62673f39e2f52c2561182c558a21cb6 (diff) | |
download | linux-stable-2aa6ba7b5ad3189cc27f14540aa2f57f0ed8df4b.tar.gz linux-stable-2aa6ba7b5ad3189cc27f14540aa2f57f0ed8df4b.tar.bz2 linux-stable-2aa6ba7b5ad3189cc27f14540aa2f57f0ed8df4b.zip |
xfs: clear _XBF_PAGES from buffers when readahead page
If we try to allocate memory pages to back an xfs_buf that we're trying
to read, it's possible that we'll be so short on memory that the page
allocation fails. For a blocking read we'll just wait, but for
readahead we simply dump all the pages we've collected so far.
Unfortunately, after dumping the pages we neglect to clear the
_XBF_PAGES state, which means that the subsequent call to xfs_buf_free
thinks that b_pages still points to pages we own. It then double-frees
the b_pages pages.
This results in screaming about negative page refcounts from the memory
manager, which xfs oughtn't be triggering. To reproduce this case,
mount a filesystem where the size of the inodes far outweighs the
availalble memory (a ~500M inode filesystem on a VM with 300MB memory
did the trick here) and run bulkstat in parallel with other memory
eating processes to put a huge load on the system. The "check summary"
phase of xfs_scrub also works for this purpose.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Diffstat (limited to 'fs/xfs/xfs_buf.c')
-rw-r--r-- | fs/xfs/xfs_buf.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 7f0a01f7b592..ac3b4db519df 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -422,6 +422,7 @@ retry: out_free_pages: for (i = 0; i < bp->b_page_count; i++) __free_page(bp->b_pages[i]); + bp->b_flags &= ~_XBF_PAGES; return error; } |