dm-delay: fix hung task introduced by kthread mode

If the worker thread is not woken due to a bio, then it is not woken at
all. This causes the hung task check to trigger. This occurs, for
instance, when no bios are submitted. Also when a delay of 0 is
configured, delay_bio() returns without waking the worker.

Prevent the hung task check from triggering by creating the thread with
kthread_run() instead of using kthread_create() directly.

Fixes: 70bbeb29fab0 ("dm delay: for short delays, use kthread instead of timers and wq")
Signed-off-by: Joel Colledge <joel.colledge@linbit.com>
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
index eec0daa4b227a45049c48b69b21ac6507cdcadb6..4ba12d53699499b02a930f8e0be9f536ac555000 100644 (file)
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -269,8 +269,7 @@ out:
                 * In case of small requested delays, use kthread instead of
                 * timers and workqueue to achieve better latency.
                 */
-               dc->worker = kthread_create(&flush_worker_fn, dc,
-                                           "dm-delay-flush-worker");
+               dc->worker = kthread_run(&flush_worker_fn, dc, "dm-delay-flush-worker");
                if (IS_ERR(dc->worker)) {
                        ret = PTR_ERR(dc->worker);
                        dc->worker = NULL;