3.16.7-ckt20 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Junichi Nomura <j-nomura@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Fixes: ab7c7bb6f4ab ("dm: hold suspend_lock while suspending device during device deletion")
Acked-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
drivers/md/dm.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index b3fdf9cfbeb9..91b239489785 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2413,7 +2413,6 @@ static void __dm_destroy(struct mapped_device *md, bool wait)
might_sleep();
spin_lock(&_minor_lock);
- map = dm_get_live_table(md, &srcu_idx);
idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
set_bit(DMF_FREEING, &md->flags);
spin_unlock(&_minor_lock);
@@ -2423,14 +2422,14 @@ 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,
--
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