3.16.7-ckt20 -stable review patch. If anyone has any objections, please let me know.
------------------ From: Junichi Nomura <[email protected]> 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 <[email protected]> Fixes: ab7c7bb6f4ab ("dm: hold suspend_lock while suspending device during device deletion") Acked-by: Mikulas Patocka <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques <[email protected]> --- 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, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
