linux-kernel - Re: [regression 2.6.39-rc2][bisected] "perf, x86: P4 PMU - Read proper MSR register to catch" and NMIs

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Message-ID: <20110407143858.GA18616@digium.com>
Date:	Thu, 7 Apr 2011 09:38:58 -0500
From:	Shaun Ruffell <sruffell@...ium.com>
To:	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Don Zickus <dzickus@...hat.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [regression 2.6.39-rc2][bisected] "perf, x86: P4 PMU - Read
	proper MSR register to catch" and NMIs

On Thu, Apr 07, 2011 at 07:18:50AM +0400, Cyrill Gorcunov wrote:
> On Thursday, April 7, 2011, Don Zickus <dzickus@...hat.com> wrote:
>> On Wed, Apr 06, 2011 at 05:30:36PM -0500, Shaun Ruffell wrote:
>>>
>>> I was able to bisect it down to commit 242214f9c1eeaae40, but I'm not
>>> certain where to go from here.  Is this something that is already known
>>> or is there more information I should try to collect?
>>
>> Nope, this is an ongoing issue.  What happened was the perf P4 nmi handler
>> was swallowing all the NMIs.  My patch fixed that and exposed a double NMI
>> problem.  We have been chasing it for a couple of months.  I think Cyril
>> was finally able to duplicate it (as he wrote the P4 code).  I have
>> confidence that he will find a fix for it soon. :-)
>>
>> Thanks for the report though!
> 
> Hi, yeah, i got it too and i hope to fix this issue soon. Will ping as
> only get working fix.

Don, Cyrill,

Thanks for the explanation and my apologies for not relating the
previous discussions about this to what I was seeing. This issue would
be a blocker for any 2.6.39 final right?

Cyrill, I would be more than happy to test any patches. It's relatively
quick for me to reproduce.

Thanks,
Shaun
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