sched: Fix broken assertion

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>

1 files changed, 2 insertions, 1 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 7be88a7be047..720df108a2d6 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2041,7 +2041,8 @@ 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);