linux-kernel - Re: Uhhuh. NMI received for unknown reason 2c on CPU 0.

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Message-ID: <510A2B1C.1060108@suse.cz>
Date:	Thu, 31 Jan 2013 09:28:12 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	Borislav Petkov <bp@...en8.de>, "Rafael J. Wysocki" <rjw@...k.pl>,
	Bjorn Helgaas <bhelgaas@...gle.com>, x86@...nel.org,
	lkml <linux-kernel@...r.kernel.org>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>
Subject: Re: Uhhuh. NMI received for unknown reason 2c on CPU 0.

On 01/31/2013 08:09 AM, Borislav Petkov wrote:
> On Thu, Jan 31, 2013 at 01:54:56AM +0100, Rafael J. Wysocki wrote:
>> On Thursday, January 31, 2013 12:47:40 AM Jiri Slaby wrote:
>>> On 01/31/2013 12:12 AM, Jiri Slaby wrote:
>>>> I think I will start with commenting parts of `power' script to see
>>>> exactly which of the power savings cause this.
>>>
>>> ... NMI watchdog. If I remove it from the script, the problem
>>> disappears. If I try it alone, I have those NMIs.
>>
>> Well, beats me. :-(
>>
>> I suspect that it doesn't quiesce itself sufficiently before image restoration
>> and we get some crosstalk between the boot kernel and the image kernel.
> 
> Well, I did what Jiri said causes it:
> 
> echo 0 > /proc/sys/kernel/nmi_watchdog
> 
> No NMI.
> 
> BUT(!), if I start powertop and set all tunables in the "Tunables" tab
> to "Good", then suspend to disk, when I resume I get the NMI and this
> time the unknown reason is 0x3c. Sounds like this needs bisection...

And, does it happen if you switch all of them but NMI wtd in there?

And if I pass nmi_watchdog=0 to the image kernel, it should be gone I guess.

-- 
js
suse labs
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