Re: CPU Lockups in KVM with deferred hrtimer rearming

Thomas Gleixner
2026-04-21T16:30:48Z

On Tue, Apr 21 2026 at 13:32, Peter Zijlstra wrote:
> On Tue, Apr 21, 2026 at 01:18:58PM +0200, Peter Zijlstra wrote:
>> > /*
>> > + * This is sadly required due to KVM, which invokes regular
>> > + * interrupt handlers with interrupt disabled state in @regs.
>> > + */
>> > + instrumentation_begin();
>> > + hrtimer_rearm_deferred();
>> > + instrumentation_end();
>> > +
>> > + /*
>> > * IRQ flags state is correct already. Just tell RCU if it
>> > * was not watching on entry.
>> > */
>
> Ohhh, wait. What happens if you take a page-fault from NMI context? Does
> this then not result in trying to program the timer from NMI context?

Uuuurgh, yes.