diff options
| author | NeilBrown <neilb@suse.de> | 2011-09-10 17:20:21 +1000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-10-03 11:40:14 -0700 |
| commit | 97e5a85664252fd3f3f84751c7779c326df9c851 (patch) | |
| tree | becfedf06d19a4f65aa1789442c1f4268f10b9c8 | |
| parent | 045451f9de4d9b7a7a961bf2428b990edf543271 (diff) | |
Avoid dereferencing a 'request_queue' after last close.
commit 94007751bb02797ba87bac7aacee2731ac2039a3 upstream.
On the last close of an 'md' device which as been stopped, the device
is destroyed and in particular the request_queue is freed. The free
is done in a separate thread so it might happen a short time later.
__blkdev_put calls bdev_inode_switch_bdi *after* ->release has been
called.
Since commit f758eeabeb96f878c860e8f110f94ec8820822a9
bdev_inode_switch_bdi will dereference the 'old' bdi, which lives
inside a request_queue, to get a spin lock. This causes the last
close on an md device to sometime take a spin_lock which lives in
freed memory - which results in an oops.
So move the called to bdev_inode_switch_bdi before the call to
->release.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | fs/block_dev.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index 610e8e0b04b8..194cf66bc8f5 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1419,6 +1419,11 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) WARN_ON_ONCE(bdev->bd_holders); sync_blockdev(bdev); kill_bdev(bdev); + /* ->release can cause the old bdi to disappear, + * so must switch it out first + */ + bdev_inode_switch_bdi(bdev->bd_inode, + &default_backing_dev_info); } if (bdev->bd_contains == bdev) { if (disk->fops->release) @@ -1432,8 +1437,6 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) disk_put_part(bdev->bd_part); bdev->bd_part = NULL; bdev->bd_disk = NULL; - bdev_inode_switch_bdi(bdev->bd_inode, - &default_backing_dev_info); if (bdev != bdev->bd_contains) victim = bdev->bd_contains; bdev->bd_contains = NULL; |