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authorJunichi Nomura <j-nomura@ce.jp.nec.com>2015-10-01 08:31:51 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-22 14:49:34 -0700
commit6bb0388828eff3ae34ee0034b34f0d8cf89945bc (patch)
tree9640e5945df3986dfa5db10187d898731f58fee5
parentf03b7a659257a1e1c578ca36ebfd9d65bb3e2594 (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.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 0d7ab20c58df..3e32f4e31bbb 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2952,8 +2952,6 @@ 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);
@@ -2967,14 +2965,14 @@ 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,