Re: WARN_ON_ONCE() hit at kernel/events/core.c:330

Peter Zijlstra
2019-04-08T08:22:41Z

On Mon, Apr 08, 2019 at 09:12:28AM +0200, Thomas-Mich Richter wrote:
> > Does the below cure things? It's not exactly pretty, but it could just
> > do the trick.
> >
> > ---
> > diff --git a/kernel/events/core.c b/kernel/events/core.c
> > index dfc4bab0b02b..d496e6911442 100644
> > --- a/kernel/events/core.c
> > +++ b/kernel/events/core.c
> > @@ -2009,8 +2009,8 @@ event_sched_out(struct perf_event *event,
> > event->pmu->del(event, 0);
> > event->oncpu = -1;
> >
> > - if (event->pending_disable) {
> > - event->pending_disable = 0;
> > + if (event->pending_disable == smp_processor_id()) {
> > + event->pending_disable = -1;
> > state = PERF_EVENT_STATE_OFF;
> > }
> > perf_event_set_state(event, state);
> > @@ -2198,7 +2198,7 @@ EXPORT_SYMBOL_GPL(perf_event_disable);
> >
> > void perf_event_disable_inatomic(struct perf_event *event)
> > {
> > - event->pending_disable = 1;
> > + event->pending_disable = smp_processor_id();
> > irq_work_queue(&event->pending);
> > }
> >
> > @@ -5822,8 +5822,8 @@ static void perf_pending_event(struct irq_work *entry)
> > * and we won't recurse 'further'.
> > */
> >
> > - if (event->pending_disable) {
> > - event->pending_disable = 0;
> > + if (event->pending_disable == smp_processor_id()) {
> > + event->pending_disable = -1;
> > perf_event_disable_local(event);
> > }
> >
> > @@ -10236,6 +10236,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
> >
> >
> > init_waitqueue_head(&event->waitq);
> > + event->pending_disable = -1;
> > init_irq_work(&event->pending, perf_pending_event);
> >
> > mutex_init(&event->mmap_mutex);
> >
>
> Peter,
>
> very good news, your fix ran over the weekend without any hit!!!
>
> Thanks very much for your help. Do you submit this patch to the kernel mailing list?

Most excellent, let me go write a Changelog.

Could I convince you to implement arch_irq_work_raise() for s390?