[Intel-gfx] [RFC] mm, drm/i915: Mark pinned shmemfs pages as unevictable

[Dave Hansen]

On 06/06/2017 05:34 AM, Chris Wilson wrote:
> With respect to i915, we may not be the sole owner of the page at the
> point where we call shmem_read_mapping_page_gfp() as it can mmapped or
> accessed directly via the mapping internally. It is just at this point
> we know that the page will not be returned to the system until we have
> finished using it with the GPU.
> 
> An API that didn't assume the page was locked or require exclusive
> ownership would be needed for random driver usage like i915.ko

Why do you think exclusive ownership is required, btw?  What does
exclusive ownership mean, anyway?  page_count()==1 and you old the old
reference?