Re: Tapdisk failures / kernel general protection fault at xen 4.0.2rc3 / kernel pvops 2.6.32.36

[Gerd Jakobovitsch <gerd@alog.com.br>]

Hello Daniel:

I applied the patch and the bug at VM startup was solved. Thank you for 
your help.

Regards

Gerd

On 04/14/2011 02:43 PM, Daniel Stodden wrote:
> On Thu, 2011-04-14 at 12:38 -0400, Daniel Stodden wrote:
>> On Thu, 2011-04-14 at 09:15 -0400, Konrad Rzeszutek Wilk wrote:
>>> On Wed, Apr 13, 2011 at 06:02:13PM -0300, Gerd Jakobovitsch wrote:
>>>> I'm trying to run several VMs (linux hvm, with tapdisk:aio disks at
>>>> a storage over nfs) on a CentOS system, using the up-to-date version
>>>> of xen 4.0 / kernel pvops 2.6.32.x stable. With a configuration
>>>> without (most of) debug activated, I can start several instances -
>>>> I'm running 7 of them - but shortly afterwards the system stops
>>>> responding. I can't find any information on this.
>>> First time I see it.
>>>> Activating several debug configuration items, among them
>>>> DEBUG_PAGEALLOC, I get an exception as soon as I try to start up a
>>>> VM. The system reboots.
>>> Oooh, and is the log below from that situation?
>>>
>>> Daniel, any thoughs?
>> ---
>> 	  Unmap pages from the kernel linear mapping after free_pages().
>> 	  This results in a large slowdown, but helps to find certain types
>> 	  of memory corruption.
>>
>> Stunning. Our I/O page allocator is a sort of twisted mempool. Unless
>> the allocation is explicitly modified in sysfs/, everything should stay
>> pinned. We might be just tripping over debug code alone, but I didn't
>> figure it out yet.
> Ah, that's just missing Dominic's spinlock fix.
>
> http://xenbits.xen.org/gitweb/?p=people/dstodden/linux.git;a=commit;h=a765257af7e28c41bd776c3e03615539597eb592
>
> Daniel
>