Re: NOHZ: WARNING: at arch/x86/kernel/smp.c:123native_smp_send_reschedule, round 2

[Borislav Petkov]

On Mon, May 20, 2013 at 02:23:37PM +0800, Michael Wang wrote:
> On 05/20/2013 12:50 PM, Borislav Petkov wrote:
> > On Mon, May 20, 2013 at 11:16:33AM +0800, Michael Wang wrote:
> >> I suppose the reason is that the cpu we passed to
> >> mod_delayed_work_on() has a chance to become offline before we
> >> disabled irq, what about check it before send resched ipi? like:
> > 
> > I think this is only addressing the symptoms - what we should be doing
> > instead is asking ourselves why are we even scheduling work on a cpu if
> > the machine goes offline?
> > 
> > I don't know though who should be responsible for killing all that
> > work - the workqueue itself or the guy who created it, i.e. cpufreq
> > governor...
> 
> So there are two questions here:
> 1. Is gov_queue_work() want to queue the work on offline cpu?
> 2. Is mod_delayed_work_on() allow offline cpu?
> 
> I guess both should be false?

Well, if we don't allow queueing work on a cpu which goes offline, i.e.
#2, the problem should be solved.

Tejun?

Here are the splats: http://marc.info/?l=linux-kernel&m=136879901425951

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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