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Date: Thu, 8 May 2014 09:40:12 +0400
From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>, Don Zickus <dzickus@redhat.com>
Subject: Re: perf_fuzzer crash on pentium 4
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On Thu, May 08, 2014 at 01:14:56AM -0400, Vince Weaver wrote:
> > 
> > There were a bug in p4 pmu Don (CC'ed) fixed not that long ago but I fear
> > not all corner cases might be covered yet.
> 
> I hit the NMI warnings somewhat often on Intel hardware (Haswell, Core2) 
> but it usually doesn't make the system unusable like it does on p4.
> 
> I can try to get a trace, although I'm not sure it will be useful.  I 
> spent a lot of time getting a reproducible test case for the same warnings 
> on core2 and it was unclear what the proble was and it was never fixed.
> 
> The messages look like this:
> 
> [ 2944.203423] Uhhuh. NMI received for unknown reason 31 on CPU 0.
> [ 2944.208006] Do you have a strange power saving mode enabled?
> [ 2944.208006] Dazed and confused, but trying to continue
> [ 2944.208006] Uhhuh. NMI received for unknown reason 21 on CPU 0.
> [ 2944.208006] Do you have a strange power saving mode enabled?
> [ 2944.208006] Dazed and confused, but trying to continue
> [ 2944.208006] Uhhuh. NMI received for unknown reason 31 on CPU 0.
> [ 2944.208006] Do you have a strange power saving mode enabled?
> [ 2944.208006] Dazed and confused, but trying to continue
> 
> repeating forever, system is unusable.

Vince, is it possible to get a trace which exactly events perf-fuzzed
pushed into the kernel? Maybe it would shed some light.