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From: Frederic Weisbecker <fweisbec@gmail.com>
To: Vince Weaver <vincent.weaver@maine.edu>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Dave Jones <davej@redhat.com>
Subject: Re: perf/tracepoint: another fuzzer generated lockup
Date: Fri, 8 Nov 2013 21:48:41 +0100	[thread overview]
Message-ID: <20131108204839.GD14606@localhost.localdomain> (raw)
In-Reply-To: <alpine.DEB.2.10.1311081515210.16519@vincent-weaver-1.um.maine.edu>

On Fri, Nov 08, 2013 at 03:23:07PM -0500, Vince Weaver wrote:
> On Fri, 8 Nov 2013, Frederic Weisbecker wrote:
> > 
> > There seem to be a loop that takes too long in intel_pmu_handle_irq(). Your two
> > previous reports seemed to suggest that lbr is involved, but not this one.
> 
> I may be wrong but I think everything between <NMI> and <EOE> is just
> noise from the NMI perf-event watchdog timer kicking in.

Ah good point.

So the pattern seem to be that irq work/perf_event_wakeup is involved, may be
interrupting a tracepoint event or so.

It would be nice if you enable CONFIG_FRAME_POINTER in your future reports
so that we get more precise traces. Or may be you actually enabled it and it
doesn't work?
 
> Why that code would be reading the LBR registers I don't know.

Yeah that's just an inconditional call to check if there is lbr branch to record.

> Vince
> 
> 

  reply	other threads:[~2013-11-08 20:48 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-08 19:45 perf/tracepoint: another fuzzer generated lockup Vince Weaver
2013-11-08 20:06 ` Vince Weaver
2013-11-08 20:02   ` Frederic Weisbecker
2013-11-08 20:23     ` Vince Weaver
2013-11-08 20:48       ` Frederic Weisbecker [this message]
2013-11-08 21:15         ` Vince Weaver
2013-11-08 22:24           ` Frederic Weisbecker
2013-11-08 22:36           ` Frederic Weisbecker
2013-11-09  1:09             ` Steven Rostedt
2013-11-09 14:10             ` Peter Zijlstra
2013-11-09 14:20               ` Frederic Weisbecker
2013-11-11 12:44                 ` Ingo Molnar
2013-11-11 15:53                   ` Peter Zijlstra
2013-11-11 21:13                     ` Ingo Molnar
2013-11-09 14:52               ` Frederic Weisbecker
2013-11-09 15:13                 ` Peter Zijlstra
2013-11-09 15:27                   ` Frederic Weisbecker
2013-11-09 15:59                     ` Peter Zijlstra
2013-11-09 16:08                       ` Frederic Weisbecker
2013-11-09 15:11             ` Peter Zijlstra
2013-11-09 15:22               ` Frederic Weisbecker
2013-11-09 15:30                 ` Peter Zijlstra
2013-11-14 15:23               ` Peter Zijlstra
2013-11-14 15:33                 ` Peter Zijlstra
2013-11-14 15:35                   ` Frederic Weisbecker
2013-11-15  1:16                   ` Masami Hiramatsu
2013-11-15 12:28                     ` Peter Zijlstra
2013-11-15 14:15                       ` Steven Rostedt
2013-11-15 14:28                         ` Frederic Weisbecker
2013-11-17  7:53                           ` Masami Hiramatsu
2013-11-17  9:43                             ` Peter Zijlstra
2013-11-14 16:03                 ` Frederic Weisbecker
2013-11-14 17:20                 ` Vince Weaver
2013-11-14 17:14                   ` Peter Zijlstra
2013-11-14 17:41                     ` Steven Rostedt
2013-11-14 19:18                     ` Vince Weaver
2013-11-19 19:18                 ` [tip:perf/urgent] ftrace, perf: Avoid infinite event generation loop tip-bot for Peter Zijlstra
2013-11-09  0:25           ` perf/tracepoint: another fuzzer generated lockup Frederic Weisbecker

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