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Subject: Re: [PATCH,RFC] perf: panic due to inclied cpu context task_ctx
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From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>, Paul Mackerras <paulus@samba.org>,
        Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org
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Date: Wed, 30 Mar 2011 17:57:39 +0200
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On Wed, 2011-03-30 at 17:52 +0200, Oleg Nesterov wrote:
> On 03/30, Peter Zijlstra wrote:
> >
> > On Wed, 2011-03-30 at 17:32 +0200, Oleg Nesterov wrote:
> > > > +#ifdef HAVE_JUMP_LABEL
> > > > +static inline
> > > > +void perf_sched_events_inc(void)
> > > > +{
> > > > +     jump_label_inc(&perf_sched_events_out);
> > > > +     smp_mb__after_atomic_inc();
> > > > +     jump_label_inc(&perf_sched_events_in);
> > > > +}
> > >
> > > probably smp_mb__after_atomic_inc() needs a comment...
> >
> > You don't need it, jump_label_inc() uses atomic_add_return() which
> > implies a full mb.
> 
> Yes, but only if HAVE_JUMP_LABEL.

argh, indeed.