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

Brad Campbell
2011-05-31T14:24:43Z

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.