Subject: Re: -next: Nov 12 - kernel BUG at kernel/sched.c:7359!

From: Peter Zijlstra <[email-masked]>
Date: Fri, 13 Nov 2009 10:06:13 +0100

On Fri, 2009-11-13 at 14:30 +0530, Sachin Sant wrote:
> Peter Zijlstra wrote:
> > So what we need to do is make the whole of select_task_rq_fair()
> > cpu_online/active_mask aware, or give up and simply punt:
> >
> > diff --git a/kernel/sched.c b/kernel/sched.c
> > index 1f2e99d..62df61c 100644
> > --- a/kernel/sched.c
> > +++ b/kernel/sched.c
> > @@ -2377,6 +2377,9 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
> >  	task_rq_unlock(rq, &flags);
> >
> >  	cpu = p->sched_class->select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
> > +	if (!cpu_active(cpu))
> > +		cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
> > +
> >  	if (cpu != orig_cpu) {
> >  		local_irq_save(flags);
> >  		rq = cpu_rq(cpu);
> >
> >
> > Something I think Mike also tried and didn't deadlock for him..
> >
> > Sachin, Mike, could you try the above snippet and verify if it does
> > indeed solve your respective issues?
> >   
> Unfortunately the above patch made things worse. With this patch
> the machine failed to boot with following oops

Ugh, more head scratching for me then..

Thanks for testing.