dm: add cond_resched() to dm_wq_work()

Otherwise the while() loop in dm_wq_work() can result in a "dead
loop" on systems that have preemption disabled. This is particularly
problematic on single cpu systems.

Cc: stable@vger.kernel.org
Signed-off-by: Pingfan Liu <piliu@redhat.com>
Acked-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 90b64bf..15b9195 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2570,6 +2570,7 @@ static void dm_wq_work(struct work_struct *work)
                        break;
 
                submit_bio_noacct(bio);
+               cond_resched();
        }
 }