Re: [PATCH v4] mm, drm/i915: mark pinned shmemfs pages as unevictable

[Dave Hansen]

On 11/5/18 3:13 AM, Kuo-Hsin Yang wrote:
> -These are currently used in two places in the kernel:
> +These are currently used in three places in the kernel:
>  
>   (1) By ramfs to mark the address spaces of its inodes when they are created,
>       and this mark remains for the life of the inode.
> @@ -154,6 +154,8 @@ These are currently used in two places in the kernel:
>       swapped out; the application must touch the pages manually if it wants to
>       ensure they're in memory.
>  
> + (3) By the i915 driver to mark pinned address space until it's unpinned.

At a minimum, I think we owe some documentation here of how to tell
approximately how much memory i915 is consuming with this mechanism.
The debugfs stuff sounds like a halfway reasonable way to approximate
it, although it's imperfect.