Re: Xen paravirt frontend block hang

["Christopher S. Aker" <caker@theshore.net>]

Jeremy Fitzhardinge wrote:
> Christopher S. Aker wrote on 12/26/07 2:33 PM,
>> Sorry for the noise if this isn't the appropriate venue for this.  I
>> posted this last month to xen-devel:
>>
>> http://lists.xensource.com/archives/html/xen-devel/2007-11/msg00777.html
>>
>> I can reliably cause a paravirt_ops Xen guest to hang during intensive
>> IO.  My current recipe is an untar/tar loop, without compression, of a
>> kernel tree.  For example:
>>
>> wget http://kernel.org/pub/linux/kernel/v2.6/linux-2.6.23.tar.bz2
>> bzip2 -d linux-2.6.23.tar.bz2
>>
>> while true;
>>   date
>>   tar xf linux-2.6.23.tar
>>   tar cf linux-2.6.23.tar linux-2.6.23
>> done
>>
>> After a few loops, anything that touches the xvd device that hung will
>> get stuck in D state.
>>
>> This happens on both a 2.6.16 and 2.6.18 dom0 (3.1.2 tools).  Paravirt
>> guests I've tried that exhibit the problem: 2.6.23.8, 2.6.23.12, and
>> 2.6.24-rc6.  It does *not* occur using the Xensource 2.6.18 domU tree
>> from 3.1.2.  In all cases, the host continues to run fine, nothing out
>> of the ordinary is logged on the dom0 side, xenstore reports the
>> status of the devices is fine.
>>
>> Can anyone reproduce this problem, or let me know what else I can
>> provide to help track this down? 
> 
> Hi,
> 
> I'll try to track this down asap.  Have you tried any other kernel
> versions?  In other words, did it just start happening, or its always
> done it?  Also, could you try 2.6.24-rc6, just to make sure it hasn't
> already been fixed (which is possible if its something that happened in
> a higher layer or something).

Were you able to give this a try?  Still doing it on pv_ops 2.6.24.

Thanks,
-Chris