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由 Andrea Righi 提交于
Parity page is incorrectly unmapped in finish_parity_scrub(), triggering a reference counter bug on i386, i.e.: [ 157.662401] kernel BUG at mm/highmem.c:349! [ 157.666725] invalid opcode: 0000 [#1] SMP PTI The reason is that kunmap(p_page) was completely left out, so we never did an unmap for the p_page and the loop unmapping the rbio page was iterating over the wrong number of stripes: unmapping should be done with nr_data instead of rbio->real_stripes. Test case to reproduce the bug: - create a raid5 btrfs filesystem: # mkfs.btrfs -m raid5 -d raid5 /dev/sdb /dev/sdc /dev/sdd /dev/sde - mount it: # mount /dev/sdb /mnt - run btrfs scrub in a loop: # while :; do btrfs scrub start -BR /mnt; done BugLink: https://bugs.launchpad.net/bugs/1812845 Fixes: 5a6ac9ea ("Btrfs, raid56: support parity scrub on raid56") CC: stable@vger.kernel.org # 4.4+ Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de> Signed-off-by: NAndrea Righi <andrea.righi@canonical.com> Reviewed-by: NDavid Sterba <dsterba@suse.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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