Re: WARNING: at arch/x86/kernel/cpu/perf_event.c:989

[Stephane Eranian]

On Mon, Feb 6, 2012 at 3:38 PM, Ingo Molnar <mingo@xxxxxxx> wrote:
>
> * Stephane Eranian <eranian@xxxxxxxxxx> wrote:
>
>> Ok, I found the problem!
>>
>> it comes from perf_adjust_freq_unthr_context() vs perf_adjust_period().
>> The latter can under certain condition stop and restart the event. So we
>> had:
>>
>> Â Â Â stop()
>> Â Â Â if (delta > 0) {
>> Â Â Â Â Â Âperf_adjust_period() {
>> Â Â Â Â Â Â Â Âif (period > 8*...) {
>> Â Â Â Â Â Â Â Â Â Âstop()
>> Â Â Â Â Â Â Â Â Â Â...
>> Â Â Â Â Â Â Â Â Â Âstart()
>> Â Â Â Â Â Â Â Â}
>> Â Â Â Â Â Â}
>> Â Â Â Â}
>> Â Â Â Âstart()
>>
>> Could have a double stop() and double start(), thus triggering the warning in
>> x86_pmu_start().
>>
>> Will post a patch shortly to fix this.
>
> Please send a patch against tip:master (or perf/urgent), on top
> of:
>
> Â84f2b9b2edc0: perf: Remove deprecated WARN_ON_ONCE()
>
> Note that I updated that patch to removed one more WARN_ON()
> than you originally sent - please add it back as appropriate, in
> the delta fix patch.
>
I have already added the warning back. Will send against tip:master

> Thanks,
>
> Â Â Â ÂIngo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/