From: Andrea Righi <andrea.righi@canonical.com>
To: Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
David Sterba <dsterba@suse.com>
Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] btrfs: raid56: properly unmap parity page in finish_parity_scrub()
Date: Wed, 13 Mar 2019 11:17:04 +0100 [thread overview]
Message-ID: <20190313101703.GA9155@xps-13> (raw)
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
Steps 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
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
---
fs/btrfs/raid56.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 1869ba8e5981..67a6f7d47402 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -2430,8 +2430,9 @@ 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);
--
2.19.1
next reply other threads:[~2019-03-13 10:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-13 10:17 Andrea Righi [this message]
2019-03-13 10:59 ` [PATCH] btrfs: raid56: properly unmap parity page in finish_parity_scrub() Johannes Thumshirn
2019-03-14 7:56 ` [PATCH v2] " Andrea Righi
2019-03-18 18:47 ` David Sterba
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