From: Mike Galbraith <efault@gmx.de>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Paul Mackerras <paulus@samba.org>
Subject: Re: [BUG] perf: hard lockup when using perf-sched
Date: Fri, 26 Mar 2010 20:10:40 +0100 [thread overview]
Message-ID: <1269630640.6331.18.camel@marge.simson.net> (raw)
In-Reply-To: <20100326172350.GC5188@nowhere>
On Fri, 2010-03-26 at 18:23 +0100, Frederic Weisbecker wrote:
> On Fri, Mar 26, 2010 at 11:11:33AM +0100, Mike Galbraith wrote:
> > perf: fix perf sched record forkbomb deadlock
> >
> > perf sched record can deadlock a box should the holder of handle->data->lock
> > take an interrupt, and then attempt to acquire an rq lock held by a CPU trying
> > to acquire the same lock. Disable interrupts.
>
>
>
> Aah.
>
> So the scenario is the following inversion?
>
> CPU0 CPU1
> sched event with rq->lock held
> grab handle->data->lock
> spin on handle->data->lock
> interrupt
> try to grab rq->lock
Yeah, handle->data->lock holder dare not try to grab any rq lock because
of sched event with rq->lock held.
-Mike
next prev parent reply other threads:[~2010-03-26 19:10 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-17 7:21 [BUG] perf: hard lockup when using perf-sched Li Zefan
2010-03-24 5:52 ` Li Zefan
2010-03-24 7:32 ` Mike Galbraith
2010-03-24 8:17 ` Mike Galbraith
2010-03-25 8:04 ` Li Zefan
2010-03-25 9:27 ` Mike Galbraith
2010-03-25 9:54 ` Peter Zijlstra
2010-03-26 10:11 ` Mike Galbraith
2010-03-26 17:23 ` Frederic Weisbecker
2010-03-26 19:10 ` Mike Galbraith [this message]
2010-03-26 19:27 ` Frederic Weisbecker
2010-03-26 20:22 ` Mike Galbraith
2010-03-26 21:41 ` Frederic Weisbecker
2010-03-26 21:45 ` Frederic Weisbecker
2010-03-29 2:01 ` Li Zefan
2010-04-02 19:07 ` [tip:perf/core] perf: Fix 'perf sched record' deadlock tip-bot for Mike Galbraith
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