From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Thu, 17 Dec 2009 12:16:31 +0000 (+0100)
Subject: sched: Fix broken assertion
X-Git-Tag: firefly_0821_release~10186^2~975
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=9f2243e5817e778ebb95101722492937b845d8c9;p=firefly-linux-kernel-4.4.55.git

sched: Fix broken assertion

commit 077614ee1e93245a3b9a4e1213659405dbeb0ba6 upstream

There's a preemption race in the set_task_cpu() debug check in
that when we get preempted after setting task->state we'd still
be on the rq proper, but fail the test.

Check for preempted tasks, since those are always on the RQ.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20091217121830.137155561@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/kernel/sched.c b/kernel/sched.c
index 94b1ca17db38..947b26df11df 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2071,7 +2071,8 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 	 * We should never call set_task_cpu() on a blocked task,
 	 * ttwu() will sort out the placement.
 	 */
-	WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING);
+	WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
+			!(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
 #endif
 
 	trace_sched_migrate_task(p, new_cpu);