By removing the device private pages from the physical address space,
this series also opens up the possibility to moving away from tracking
device private memory using struct pages in the future. This is
desirable as on systems with large amounts of memory these device
private struct pages use a signifiant amount of memory and take a
significant amount of time to initialize.

Changes in v6
-------------
- Fix maybe unused in kgd2kfd_init_zone_device()
- Replace division by PAGE_SIZE with DIV_ROUND_UP() when setting
nr_pages. This mirrors the align up that previously happened in
get_free_mem_region()

Note removed previous discussion in the cover letter relating to aarch64
and memremap_pages() as this was actually already addressed in commit
eeb8fdfcf090 ("arm64: Expose the end of the linear map in PHYSMEM_END").

Now that I stumbled over v6, same comment; planning on taking a look soon.

-- 
Cheers,

David