[Intel-gfx] [PATCH] drm/i915: Do not leak VMAs (and PPGTT VMs) of imported flinked objects

[Chris Wilson]

On Mon, Apr 20, 2015 at 01:53:03PM +0100, Tvrtko Ursulin wrote:
> >No we can't do this, as it makes close sync and so can have disasterous
> >effects on performance (though mitigated chiefly by userspace
> >agressively caching bo) and also the unbind is very likely to fail,
> >though admittedly the fbcon copy should be before X starts (ab)using
> >signals - hence nasty WARN_ON.
> >
> >Plus also walking this linear list is quite painful in certain abusive
> >tests. My preference for fixing this bug would be via vma active
> >references and auto-unbinding on retirement after a close.
> 
> Why this is any different today with GEM_CLOSE having pretty similar
> VMA unbind loop? Is the typical (and interesting) case not that
> GEM_CLOSE will trigger gem_object_close and gem_object_free at the
> same invocation?

We have such a cleanup loop in free_object, but we have an active
reference to ensure that we only do so once the object is idle (and
unbinding won't cause to wait).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre