[Intel-gfx] [PATCH 4/4] drm/i915: Add cpu fault handler for mmap_offset

[Chris Wilson]

Quoting Abdiel Janulgue (2019-11-19 11:37:10)
> Fault handler to handle missing pages for shmem-backed objects.
> 
> v2: bail out of inserting PTEs when failing to insert the
>     fault address
> v3: has struct page check
> v4: Add self-test for validating CPU fault handler to ensure PTEs
>     are revoked when an object is unbound.
> v5: Add comment where PTEs are revoked (Chris)
> 
> Signed-off-by: Abdiel Janulgue <abdiel.janulgue at linux.intel.com>
> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Uh oh, the mmap() does remain valid past a gem_close() -- the
vm_area_struct is lacking a reference to the object?
-Chris