diff options
| author | Junichi Nomura <j-nomura@ce.jp.nec.com> | 2015-10-01 08:31:51 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-10-22 14:43:26 -0700 |
| commit | 16d4c27cb8ca5b7955efbf4389e1537ff948f7ef (patch) | |
| tree | 0d86527c166a73b27a400ec787df29c1248762fa | |
| parent | 2058efbcb0eb148db2086266cfb048da42fd0a93 (diff) | |
dm: fix AB-BA deadlock in __dm_destroy()
commit 2a708cff93f1845b9239bc7d6310aef54e716c6a upstream.
__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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 697f34fba06b..8b72ceee0f61 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2925,8 +2925,6 @@ 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); @@ -2940,14 +2938,14 @@ 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, |