https://github.com/torvalds/linux
Revision 2aa6ba7b5ad3189cc27f14540aa2f57f0ed8df4b authored by Darrick J. Wong on 26 January 2017, 04:24:57 UTC, committed by Darrick J. Wong on 26 January 2017, 04:24:57 UTC
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>
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Tip revision: 2aa6ba7b5ad3189cc27f14540aa2f57f0ed8df4b authored by Darrick J. Wong on 26 January 2017, 04:24:57 UTC
xfs: clear _XBF_PAGES from buffers when readahead page
xfs: clear _XBF_PAGES from buffers when readahead page
Tip revision: 2aa6ba7
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| firmware | ||
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| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
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| security | ||
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| .cocciconfig | -rw-r--r-- | 59 bytes |
| .get_maintainer.ignore | -rw-r--r-- | 31 bytes |
| .gitattributes | -rw-r--r-- | 30 bytes |
| .gitignore | -rw-r--r-- | 1.3 KB |
| .mailmap | -rw-r--r-- | 7.7 KB |
| COPYING | -rw-r--r-- | 18.3 KB |
| CREDITS | -rw-r--r-- | 96.0 KB |
| Kbuild | -rw-r--r-- | 2.8 KB |
| Kconfig | -rw-r--r-- | 252 bytes |
| MAINTAINERS | -rw-r--r-- | 382.5 KB |
| Makefile | -rw-r--r-- | 57.6 KB |
| README | -rw-r--r-- | 722 bytes |
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