[Intel-gfx] [PATCH] drm/i915/userptr: detect un-GUP-able pages early

[Chris Wilson]

Quoting Chris Wilson (2021-01-15 16:56:42)
> Quoting Jinoh Kang (2021-01-15 16:23:31)
> > If GUP-ineligible pages are passed to a GEM userptr object, -EFAULT is
> > returned only when the object is actually bound.
> > 
> > The xf86-video-intel userspace driver cannot differentiate this
> > condition, and marks the GPU as wedged.
> 
> The idea was to call gem_set_domain on the object to validate the pages
> after creation. I only did that for read-only... I did however make mesa
> use set-domain for validation.

Hmm, I remember a reason why we wanted to be lazy in populating the
pages was that we would often be called to create a map that was never
used. So the additional gup + bind was measurable, and we would rather
just have a probe.
-Chris