Re: [PATCH] sched: Further restrict the preemption modes

Douglas Freimuth
2026-02-25T18:30:36Z

On 2/25/26 11:33 AM, Christian Borntraeger wrote:
> Am 24.02.26 um 21:30 schrieb Ilya Leoshkevich:
>> Finally, what is the worker doing? I looked at __queue_work() kstacks,
>> and they all come from irqfd_wakeup().
>>
>> irqfd_wakeup() calls arch-specific kvm_arch_set_irq_inatomic(), which
>> is implemented on x86 and not implemented on s390.
>>
>>
>> This may explain why we on s390 are the first to see this.
>>
>>
>> Christian, do you think if it would make sense to
>> implement kvm_arch_set_irq_inatomic() on s390?
>
> So in fact Doug is working on that at the moment. There are some corner
> cases where we had concerns as we have to pin the guest pages holding
> the interrupt bits. This was secure execution, I need to followup if
> we have already solved those cases. But we can try if the current patch
> will help this particular problem.
>
> If yes, then we can try to speed up the work on this.
>
> Christian

Christian, the patch is very close to ready. The last step, I rebased on
Master today to pickup the latest changes to interrupt.c. I am building
that now and will test for non-SE and SE environments. I have been
testing my solution for SE environments for a few weeks and it seems to
cover the use cases I have tested.