Re: [PATCH] drm/i915/selftests: Fix unlocked mm.stolen in reset selftest

[Andi Shyti <andi.shyti@kernel.org>]

Hi Sebastian,

> On Wed Aug 26, 2026 at 7:31 PM CEST, Andi Shyti wrote:
> > Have you checked sashiko's reviews? They look valid to me.
> >
> I checked, and there are already existing issues, probably wrth fixing,
> but they're outside the scope of this patch.

actually you are in the middle of those issues :-)

> > ...
> >
> >> @@ -95,9 +96,12 @@ __igt_reset_stolen(struct intel_gt *gt,
> >>  				      ggtt->error_capture.start,
> >>  				      PAGE_SIZE);
> >>  
> >> -		if (!__drm_mm_interval_first(&gt->i915->mm.stolen,
> >> -					     page << PAGE_SHIFT,
> >> -					     ((page + 1) << PAGE_SHIFT) - 1))
> >> +		mutex_lock(&gt->i915->mm.stolen_lock);
> >> +		unused = !__drm_mm_interval_first(&gt->i915->mm.stolen,
> >> +						  page << PAGE_SHIFT,
> >> +						  ((page + 1) << PAGE_SHIFT) - 1);
> >> +		mutex_unlock(&gt->i915->mm.stolen_lock);
> >> +		if (unused)
> >
> > this is always false.
> Nothing really changes here, even if the if statement is always false,
> we still need to guarantee safe access.

I'm not getting your point. Do you mean that if nothing changes I
can add things like "if (0) do_whatever_you_want;"?

Thanks,
Andi