1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 4d4b386..398b3f9 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1360,8 +1360,16 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev)
 	struct task_struct *p;
 	struct rt_rq *rt_rq = &rq->rt;
 
-	if (need_pull_rt_task(rq, prev))
+	if (need_pull_rt_task(rq, prev)) {
 		pull_rt_task(rq);
+		/*
+		 * pull_rt_task() can drop (and re-acquire) rq->lock; this
+		 * means a dl task can slip in, in which case we need to
+		 * re-start task selection.
+		 */
+		if (unlikely(rq->dl.dl_nr_running))
+			return RETRY_TASK;
+	}
 
 	if (!rt_rq->rt_nr_running)
 		return NULL;