Re: perf_fuzzer crash on pentium 4

[Cyrill Gorcunov <gorcunov@gmail.com>]

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.