Hi Sasha,
On Tue, Jan 12, 2016 at 5:53 PM, Christoph Lameter <cl@xxxxxxxxx> wrote:
> On Tue, 12 Jan 2016, Shiraz Hashim wrote:
>
>> > + refresh_cpu_vm_stats(false);
>> > + cancel_delayed_work(this_cpu_ptr(&vmstat_work));
>> >
>>
>> shouldn't this be cancel_delayed_work_sync ?
>
> Hmmm... This is executed with preemption off and the work is on the same
> cpu. If it would be able to run concurrently then we would need this.
>
> Ok but it could run from the timer interrupt if that is still on and
> occuring shortly before we go idle. Guess this needs to be similar to
> the code we execute on cpu down in the vmstat notifiers (see
> vmstat_cpuup_callback).
>
> Does this fix it? I have not been able to reproduce the issue so far.
>
> Patch against -next.
>
>
>
> Subject: vmstat: Use delayed work_sync and avoid loop.
>
> Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
>
> Index: linux/mm/vmstat.c
> ===================================================================
> --- linux.orig/mm/vmstat.c
> +++ linux/mm/vmstat.c
> @@ -1419,11 +1419,9 @@ void quiet_vmstat(void)
> if (system_state != SYSTEM_RUNNING)
> return;
>
> - do {
> - if (!cpumask_test_and_set_cpu(smp_processor_id(), cpu_stat_off))
> - cancel_delayed_work(this_cpu_ptr(&vmstat_work));
> -
> - } while (refresh_cpu_vm_stats(false));
> + refresh_cpu_vm_stats(false);
> + cancel_delayed_work_sync(this_cpu_ptr(&vmstat_work));
> + cpumask_set_cpu(smp_processor_id(), cpu_stat_off);
> }
>
> /*
Can you please give it a try, seems it is reproducing easily at your end.
--
regards
Shiraz Hashim
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