Re: BUG: at kernel/sched.c:4031 __schedule()

Dirk Behme
2007-04-07T07:49:49Z

Oleg Kechin wrote:
> Hi
> I run 2.6.20-rt8 kernel on board like innovator1510 (OMAP5910 cpu)
> I notice in boot string:
> BUG: at kernel/sched.c:4031 __schedule()
> kernel complain interrupts are enabled after schedule.
>
> digging in sched.c I figured out that interrupts are disabled when cpu
> enter __sched(),
> but are enabled when it went out.
> Playing with the code i can find out, that problem is in the next
> fragment: (line 4024)
>
> if (likely(prev != next)) {
> next->timestamp = now;
> rq->nr_switches++;
> rq->curr = next;
> ++*switch_count;
>
> prepare_task_switch(rq, next);
> prev = context_switch(rq, prev, next);
> barrier();
> trace_special_pid(prev->pid, PRIO(prev), PRIO(current));
> /*
> * this_rq must be evaluated again because prev may have moved
> * CPUs since it called schedule(), thus the 'rq' on its stack
> * frame will be invalid.
> */
> finish_task_switch(this_rq(), prev);
> __preempt_enable_no_resched();
> } else {
>
> in prepare_task_switch(rq, next); interrupts are enabled,
> but in finish_task_switch(this_rq(), prev); interrupts not disabled
> (it look not symmetrical for me).
>
> Can anybody tell - is this right behavior?
> I think interrupts should be disabled somewhere in this fragment,
> or may be, scheduler should not complain?

Looks to me that this isn't an OMAP specific question. I
think linux-rt-users@vger.kernel.org list [1] is a better
place for this question.

Did you try a more recent -rt patch? They are updated
frequently with additional fixes.

Regards

Dirk

[1] http://rt.wiki.kernel.org/index.php/Mailinglists