Re: 2.6.26-git: NULL pointer deref in __switch_to

[Patrick McHardy <kaber@trash.net>]

Simon Holm Th������������������������ wrote:
> fre, 13 06 2008 kl. 15:47 -0700, skrev Suresh Siddha: 
>> On Fri, Jun 13, 2008 at 11:24:01AM -0700, Vegard Nossum wrote:
>>> On Fri, Jun 13, 2008 at 7:42 PM, Patrick McHardy <kaber@trash.net> wrote:
>>>> I get this oops once a day, its apparently triggered by something
>>>> run by cron, but the process is a different one each time.
>>>>
>>>> Kernel is -git from yesterday shortly before the -rc6 release
>>>> (last commit is the usb-2.6 merge, the x86 patches are missing),
>>>> .config is attached.
>>>>
>>>> I'll retry with current -git, but the patches that have gone in
>>>> since I last updated don't look related.
>>>>
>>> Thanks for the report.
>>>
>>>> [62060.043009] BUG: unable to handle kernel NULL pointer dereference at
>>>> 000001ff
>>>> [62060.043009] IP: [<c0102a9b>] __switch_to+0x2f/0x118
>>>> [62060.043009] *pde = 00000000
>>>> [62060.043009] Oops: 0002 [#1] PREEMPT
>> Patrick, Do you see any other error messages before this BUG stmt? Can you
>> please provide the complete kernel log till the point of failure?
>>
> Suresh, I'm pretty sure this is the same problem that I reported two
> weeks ago [1]. I suggested that you tried running lguest and reproduced
> the problem locally, but I did not hear back from you. Now Patrick is
> reporting the same problem and is also indicating that the problem is
> correlated with his use of lguest, so I'd really like you to follow up
> on this.
>
>> I have a theory for your problem and have appended a patch to test it. Can
>> you please check if the appended patch fixes your problem.
>>
> At least for me, with this patch applied on top of -rc4 or -rc6+ the
> problem still triggered after running an lguest guest for less than 30
> seconds (the guest didn't even finish the boot of an image of Ubuntu
> with no X-server).


The patch also didn't fix the problem here, I got the same crash this
morning. Unfortunately netconsole didn't log it, but its essentially
the same as the one I posted.