Re: [PATCH v8 4/8] mshv: Use hmm_range_fault_unlocked_timeout() for region faults

[Jason Gunthorpe]

On Fri, Jul 10, 2026 at 03:12:16PM -0700, Andrew Morton wrote:
> > +	mutex_lock(&region->mreg_mutex);
> > +
> > +	if (mmu_interval_read_retry(range.notifier, range.notifier_seq)) {
> > +		mutex_unlock(&region->mreg_mutex);
> > +		cond_resched();
> > +		goto again;
> > +	}
> > +
> 
> If the calling process has realtime scheduling policy and either a)
> we're uniprocessor or b) this process and the holder of
> interval_sub->invalidate_seq are both pinned to the same CPU then
> cond_resched() won't do anything, and this might be an infinite loop?

I think hmm and kvm have had this issue for a long time? I don't see
anything in the mmu notifier locking scheme that would alleviate it at
least

So.. In terms of this series I'd leave it, it is no worse than before?

Jason