Re: [Xen-devel] Guest soft lockups with "xen: make xen_qlock_wait() nestable"

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

On 08/11/18 08:08, Juergen Gross wrote:
> On 07/11/2018 10:30, Sander Eikelenboom wrote:
>> Hi Juergen / Boris,
>>
>> Last week i tested Linux kernel 4.19.0 stable with the Xen "for-linus-4.20" 
>> branch pulled on top.
>> Unfortunately i was seeing guests lockup after some time, see below for the 
>> logging from one of the guest
>> which i was able to capture.
>> Reverting "xen: make xen_qlock_wait() nestable" 
>> 7250f6d35681dfc44749d90598a2d51a118ce2b8,
>> made the lockups disappear.
>>
>> These guests are stressed quite hard in both CPU and networking, 
>> so they are probably more susceptible to locking issues.
>>
>> System is a AMD phenom x6, running Xen-unstable.
>>
>> Any ideas ?
> 
> Just checked the hypervisor again: it seems a pending interrupt for a
> HVM/PVH vcpu won't let SCHEDOP_poll return in case interrupts are
> disabled.
> 
> I need to rework the patch for that scenario. Until then I'll revert
> it.

Thanks for looking into it.

--
Sander

> 
> Juergen
> 


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