linux-kernel - Re: KVM induced panic on 2.6.38[2367] & 2.6.39

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Message-ID: <4DE4FA2B.2050504@fnarfbargle.com>
Date:	Tue, 31 May 2011 22:24:43 +0800
From:	Brad Campbell <lists2009@...rfbargle.com>
To:	Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, linux-mm <linux-mm@...ck.org>,
	Hugh Dickins <hughd@...gle.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Izik Eidus <ieidus@...hat.com>
Subject: Re: KVM induced panic on 2.6.38[2367] & 2.6.39

On 31/05/11 18:38, Borislav Petkov wrote:
> On Tue, May 31, 2011 at 05:26:10PM +0800, Brad Campbell wrote:
>> On 31/05/11 13:47, Borislav Petkov wrote:
>>> Looks like a KSM issue. Disabling CONFIG_KSM should at least stop your
>>> machine from oopsing.
>>>
>>> Adding linux-mm.
>>>
>>
>> I initially thought that, so the second panic was produced with KSM
>> disabled from boot.
>>
>> echo 0>  /sys/kernel/mm/ksm/run
>>
>> If you still think that compiling ksm out of the kernel will prevent
>> it then I'm willing to give it a go.
>
> Ok, from looking at the code, when KSM inits, it starts the ksm kernel
> thread and it looks like your oops comes from the function that is run
> in the kernel thread - ksm_scan_thread.
>
> So even if you disable it from sysfs, it runs at least once.
>

Just to confirm, I recompiled 2.6.38.7 without KSM enabled and I've been 
unable to reproduce the bug, so it looks like you were on the money.

I've moved back to 2.6.38.7 as 2.6.39 has a painful SCSI bug that panics 
about 75% of boots, and the reboot cycle required to get luck my way 
into a working kernel is just too much hassle.

It would appear that XP zero's its memory space on bootup, so there 
would be lots of pages to merge with a couple of relatively freshly 
booted XP machines running.

Regards,
Brad.
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