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

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Message-ID: <20190408082229.GI4038@hirez.programming.kicks-ass.net>
Date:   Mon, 8 Apr 2019 10:22:29 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Thomas-Mich Richter <tmricht@...ux.ibm.com>
Cc:     Kees Cook <keescook@...omium.org>, acme@...hat.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Hendrik Brueckner <brueckner@...ux.ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: Re: WARN_ON_ONCE() hit at kernel/events/core.c:330

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?