sched: Check for stop task appearance when balancing happens

We need to do it like we do for the other higher priority classes..

Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
Cc: Michael wang <wangyun@linux.vnet.ibm.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/336561397137116@web27h.yandex.ru
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

@@ -6728,7 +6728,8 @@ static int idle_balance(struct rq *this_rq)
 out:
 	/* Is there a task of a high priority class? */
 	if (this_rq->nr_running != this_rq->cfs.h_nr_running &&
-	    (this_rq->dl.dl_nr_running ||
+	    ((this_rq->stop && this_rq->stop->on_rq) ||
+	     this_rq->dl.dl_nr_running ||
 	     (this_rq->rt.rt_nr_running && !rt_rq_throttled(&this_rq->rt))))
 		pulled_task = -1;