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| author | Andrea Righi <andrea.righi@canonical.com> | 2019-03-14 10:56:28 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-03 07:25:15 +0300 |
| commit | 2b95e85fb9b14a8e5616d1342181aba486fecace (patch) | |
| tree | e2e6c55c4c16ff79131c5b29c4a1d4fc5e6c6415 | |
| parent | da04627d0ab4dc83c9dfc27f94b4ada77287ae09 (diff) | |
| download | linux-2b95e85fb9b14a8e5616d1342181aba486fecace.tar.xz | |
btrfs: raid56: properly unmap parity page in finish_parity_scrub()
commit 3897b6f0a859288c22fb793fad11ec2327e60fcd upstream.
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: 5a6ac9eacb49 ("Btrfs, raid56: support parity scrub on raid56")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/btrfs/raid56.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c index 2e995e565633..1e35a2327478 100644 --- a/fs/btrfs/raid56.c +++ b/fs/btrfs/raid56.c @@ -2414,8 +2414,9 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio, bitmap_clear(rbio->dbitmap, pagenr, 1); kunmap(p); - for (stripe = 0; stripe < rbio->real_stripes; stripe++) + for (stripe = 0; stripe < nr_data; stripe++) kunmap(page_in_rbio(rbio, stripe, pagenr, 0)); + kunmap(p_page); } __free_page(p_page); |