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| 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 14:49:34 -0700 |
| commit | 6bb0388828eff3ae34ee0034b34f0d8cf89945bc (patch) | |
| tree | 9640e5945df3986dfa5db10187d898731f58fee5 | |
| parent | f03b7a659257a1e1c578ca36ebfd9d65bb3e2594 (diff) | |
| download | lwn-6bb0388828eff3ae34ee0034b34f0d8cf89945bc.tar.gz lwn-6bb0388828eff3ae34ee0034b34f0d8cf89945bc.zip | |
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 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, |