[Intel-gfx] [PATCH] drm/i915: Double check vma placement upon gaining the vm lock

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-11-26 17:04:43)
> 
> On 26/11/2019 15:26, Chris Wilson wrote:
> > diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> > index e5512f26e20a..f6e661428b02 100644
> > --- a/drivers/gpu/drm/i915/i915_vma.c
> > +++ b/drivers/gpu/drm/i915/i915_vma.c
> > @@ -905,6 +905,12 @@ int i915_vma_pin(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
> >                       __i915_vma_set_map_and_fenceable(vma);
> >       }
> >   
> > +     /* Somebody else managed to gazump our placement? */
> > +     if (i915_vma_misplaced(vma, size, alignment, flags)) {
> > +             err = -EAGAIN;
> > +             goto err_active;
> > +     }
> > +
> 
> What about other callers? They will not be expecting this.

The other paths should be quite happy with -EAGAIN from vma_pin, it's
already part of their retry procedure. If not, there's always more duct
tape. Hopefully the replacement is much simpler (stop laughing back
there).
-Chris