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| author | Junichi Nomura <j-nomura@ce.jp.nec.com> | 2015-10-01 08:31:51 +0000 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2016-10-20 10:49:14 +0200 |
| commit | 52342f2c308ee92f3e9516c4c2ceb5937bc881e7 (patch) | |
| tree | 8e387cb69cfcaa094c95d764dd882d954cb9e33e | |
| parent | 64124d136db6d4fe8508125c6378d8d3fe89ad0c (diff) | |
| download | lwn-52342f2c308ee92f3e9516c4c2ceb5937bc881e7.tar.gz lwn-52342f2c308ee92f3e9516c4c2ceb5937bc881e7.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: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | drivers/md/dm.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 5a0b1742f794..78ab0a131cf1 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2434,7 +2434,6 @@ 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); @@ -2444,14 +2443,14 @@ 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, |