Regression warning about 4.4.17+18 / 4.6.7 / 4.7+ and Xen

[Stefan Bader]

On 22.08.2016 15:18, Tim Gardner wrote:
> On 08/22/2016 04:07 AM, Stefan Bader wrote:
>> There has been a recent (maybe not that recent, it was in 4.7) kernel regression
>> for Xen which made its way back to several stable trees[1]:
>>
>>   xenbus: don't BUG() on user mode induced condition
>>
>> It appears there is a fix on patchworks[2] but as of today was not included, yet
>> in upstream Linux.
>>
>> For Yakkety the regression is part of the 4.6.0-11 unstable package. For Xenial
>> it is part of the pending next SRU cycle (master-next). I did a quick test with
>> the proposed patch on top of 4.6 in yakkety/master-next and it allowed me to
>> starts VMs again. Not sure whether we want to pick that additional patch or back
>> out the stable change introducing the problem. But either way the master-next
>> branches of both Xenial and Yakkety will cause a Xen regression as they are now.
>>
>> The effect is that tools like xenstore-ls or xenstore-write no longer work and
>> it is no longer possible to start any VMs.
>>
>> -Stefan
>>
>> [1] https://lists.xenproject.org/archives/html/xen-devel/2016-08/msg02496.html
>> [2] https://patchwork.kernel.org/patch/9281193/
>>
>>
>>
> 
> Looks like we should apply the one liner patchworks patch.
> 
Sounds sensible, yes. For Xenial there is hope that by next week maybe the fix
went upstream for picking. The warning is also intended as a marker, so we do
not forget to look at this.

-Stefan

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