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| author | Junichi Nomura <j-nomura@ce.jp.nec.com> | 2015-10-01 10:31:51 +0200 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2015-10-01 16:40:20 +0200 |
| commit | 2a708cff93f1845b9239bc7d6310aef54e716c6a (patch) | |
| tree | f44436bb8bc6f700ab1ea8d042c505ad2910a428 /drivers/md/dm.c | |
| parent | Linux 4.3-rc3 (diff) | |
| download | linux-2a708cff93f1845b9239bc7d6310aef54e716c6a.tar.xz linux-2a708cff93f1845b9239bc7d6310aef54e716c6a.zip | |
dm: fix AB-BA deadlock in __dm_destroy()
__dm_destroy() takes io_barrier SRCU lock (dm_get_live_table) and
suspend_lock in reverse order. Doing so can cause AB-BA deadlock:
__dm_destroy dm_swap_table
---------------------------------------------------
mutex_lock(suspend_lock)
dm_get_live_table()
srcu_read_lock(io_barrier)
dm_sync_table()
synchronize_srcu(io_barrier)
.. waiting for dm_put_live_table()
mutex_lock(suspend_lock)
.. waiting for suspend_lock
Fix this by taking the locks in proper order.
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Fixes: ab7c7bb6f4ab ("dm: hold suspend_lock while suspending device during device deletion")
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
Diffstat (limited to 'drivers/md/dm.c')
| -rw-r--r-- | drivers/md/dm.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 6264781dc69a..7289ece3b560 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2837,8 +2837,6 @@ static void __dm_destroy(struct mapped_device *md, bool wait) might_sleep(); - map = dm_get_live_table(md, &srcu_idx); - spin_lock(&_minor_lock); idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md)))); set_bit(DMF_FREEING, &md->flags); @@ -2852,14 +2850,14 @@ static void __dm_destroy(struct mapped_device *md, bool wait) * do not race with internal suspend. */ mutex_lock(&md->suspend_lock); + map = dm_get_live_table(md, &srcu_idx); if (!dm_suspended_md(md)) { dm_table_presuspend_targets(map); dm_table_postsuspend_targets(map); } - mutex_unlock(&md->suspend_lock); - /* dm_put_live_table must be before msleep, otherwise deadlock is possible */ dm_put_live_table(md, srcu_idx); + mutex_unlock(&md->suspend_lock); /* * Rare, but there may be I/O requests still going to complete, |