From: Gautham R Shenoy <ego@in.ibm.com>

yield() in wait_task_inactive(), can cause a high priority thread to be
scheduled back in, and there by loop forever while it is waiting for some
lower priority thread which is unfortunately still on the runqueue.

Use schedule_timeout_uninterruptible(1) instead.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Credit: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/sched.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

diff -puN kernel/sched.c~rt-ptracer-can-monopolize-cpu-was-cpu-hotplug-and-real-time kernel/sched.c
--- a/kernel/sched.c~rt-ptracer-can-monopolize-cpu-was-cpu-hotplug-and-real-time
+++ a/kernel/sched.c
@@ -1109,7 +1109,7 @@ repeat:
 	 * yield - it could be a while.
 	 */
 	if (unlikely(on_rq)) {
-		yield();
+		schedule_timeout_uninterruptible(1);
 		goto repeat;
 	}
 
_