On Fri, Nov 12, 2021 at 04:08:16PM +0100, Joao Martins wrote:

This series converts device-dax to use compound pages, and moves away from the
'struct page per basepage on PMD/PUD' that is done today. Doing so, unlocks a
few noticeable improvements on unpin_user_pages() and makes device-dax+altmap case
4x times faster in pinning (numbers below and in last patch).

I like it - aside from performance this series is important to clean
up the ZONE_DEVICE refcounting mess as it means that only fsdax will
be installing tail pages as PMD entries.

Thanks,
Jason