Re: 2.6.38-rc2: Uhhuh. NMI received for unknown reason 2d on CPU 0.

From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Dave Airlie <airlied@gmail.com>,
	George Spelvin <linux@horizon.com>,
	a.p.zijlstra@chello.nl, dzickus@redhat.com, eranian@google.com,
	linux-kernel@vger.kernel.org, ming.m.lin@intel.com
Subject: Re: 2.6.38-rc2: Uhhuh. NMI received for unknown reason 2d on CPU 0.
Date: Wed, 16 Feb 2011 12:33:32 +0300	[thread overview]
Message-ID: <AANLkTi=JDw=BNg1ys5ifkPwY7XpapMz-1hn5bAXmYYfg@mail.gmail.com> (raw)
In-Reply-To: <20110216085605.GA18842@elte.hu>

On 2/16/11, Ingo Molnar <mingo@elte.hu> wrote:
>
> * Cyrill Gorcunov <gorcunov@gmail.com> wrote:
>
>> On Wed, Feb 16, 2011 at 11:37 AM, Ingo Molnar <mingo@elte.hu> wrote:
>> ...
>> >> >>
>> >> >
>> >> > Ping on this problem, still seeing
>> >> >
>> >> > Uhhuh. NMI received for unknown reason 3c on CPU 0.
>> >> > Do you have a strange power saving mode enabled?
>> >> > Dazed and confused, but trying to continue
>> >> >
>> >> > on my Pentium-D system here with latest Linus head.
>> >> >
>> >> > its sometimes 3c, sometimes 3d, I'm going to bisect and push for
>> >> > reverts if nobody still has any clue about how to fix this.
>> >> >
>> >> > Dave.
>> >> >
>> >>
>> >> We still trying to resolve it but without success yet. There is no
>> >> easy way to revert it. One of the option might be to disable perf on
>> >> p4 for a while. If this is acceptable -- i'll cook such patch and send
>> >> it to Ingo. Hm?
>> >
>> > That's not really acceptable - need to fix it or revert it to the last
>> > working
>> > state. Which commit broke it?
>> >
>> > Thanks,
>> >
>> >        Ingo
>> >
>>
>> I can't say you the commit id after which unknown-nmi start happening
>> (i'm out of git tree
>> at moment) but even then this commit should not be reverted since the
>> problem is in
>> p4 code not in the rest of perf system.
>>
>> I have two patches here (attached) and would really appreciate of
>> their testing on HT machine
>> together with kgdb bootup tests enabled. Dave could you please?
>
> Could these patches fix Dave's non-kgdb problem? Dave isnt using kgdb but is
> probably using perf which triggers NMIs? Dave, can you confirm that?
>
> And it's a spurious NMI message, not actual lockup or other misbehavior,
> right?
>
> Thanks,
>
> 	Ingo
>
For nonkgdb case 'unflagged nmi fix' patch should be enough. i've
tested it on non-ht machine by self. without it there is no lockup
but only a message about unknown nmi.

for hr-machine with kgdb the things go harder, Don reported lockup on
boot. The second patch might help but i cant test it (here i need help
in testing)