From: Peter Zijlstra <peterz@infradead.org>
To: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Vince Weaver <vincent.weaver@maine.edu>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Stephane Eranian <eranian@gmail.com>,
"Paul E. McKenney" <paulmck@us.ibm.com>
Subject: Re: perf: aux area related crash and warnings
Date: Thu, 18 Jun 2015 12:24:10 +0200 [thread overview]
Message-ID: <20150618102410.GJ19282@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <87bngd2wbg.fsf@ashishki-desk.ger.corp.intel.com>
On Thu, Jun 18, 2015 at 12:35:31PM +0300, Alexander Shishkin wrote:
> Ingo Molnar <mingo@kernel.org> writes:
>
> > * Alexander Shishkin <alexander.shishkin@linux.intel.com> wrote:
> >
> >> +void rb_free_aux(struct ring_buffer *rb)
> >> +{
> >> + /*
> >> + * hold rb::refcount to make sure rb doesn't disappear
> >> + * before aux pages are freed
> >> + */
> >> + if (WARN_ON_ONCE(!atomic_inc_not_zero(&rb->refcount)))
> >> + return;
> >> +
> >> + if (atomic_dec_and_test(&rb->aux_refcount))
> >> + call_rcu(&rb->rcu_head, rb_free_rcu);
> >> + else
> >> + ring_buffer_put(rb); /* matches the increment above */
> >
> > Is call_rcu() NMI-safe? I don't think so ...
>
> Actually, we couldn't establish that without Paul's help.
I was fairly sure it was not, Paul did confirm last night it is indeed
not.
next prev parent reply other threads:[~2015-06-18 10:24 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-12 3:15 perf: aux area related crash and warnings Vince Weaver
2015-06-12 18:42 ` Vince Weaver
2015-06-15 12:20 ` Peter Zijlstra
2015-06-15 12:49 ` Alexander Shishkin
2015-06-15 20:24 ` Ingo Molnar
2015-06-16 11:37 ` Alexander Shishkin
2015-06-18 9:09 ` Ingo Molnar
2015-06-18 9:35 ` Alexander Shishkin
2015-06-18 10:24 ` Peter Zijlstra [this message]
2015-06-18 16:30 ` Paul E. McKenney
2015-06-18 10:32 ` Peter Zijlstra
2015-06-18 13:11 ` Alexander Shishkin
2015-06-19 14:21 ` Vince Weaver
2015-07-06 15:34 ` [tip:perf/urgent] perf: Fix AUX buffer refcounting tip-bot for Peter Zijlstra
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