[PATCH v4 00/10] Add MEMORY_DEVICE_COHERENT for coherent device memory mapping

[Andrew Morton]

On Wed, 26 Jan 2022 21:09:39 -0600 Alex Sierra <alex.sierra at amd.com> wrote:

> This patch series introduces MEMORY_DEVICE_COHERENT, a type of memory
> owned by a device that can be mapped into CPU page tables like
> MEMORY_DEVICE_GENERIC and can also be migrated like
> MEMORY_DEVICE_PRIVATE.

Some more reviewer input appears to be desirable here.

I was going to tentatively add it to -mm and -next, but problems. 
5.17-rc1's mm/migrate.c:migrate_vma_check_page() is rather different
from the tree you patched.  Please redo, refresh and resend?