Alistair Popple wrote:

The rmap doesn't currently support adding a PUD mapping of a
folio. This patch adds support for entire PUD mappings of folios,
primarily to allow for more standard refcounting of device DAX
folios. Currently DAX is the only user of this and it doesn't require
support for partially mapped PUD-sized folios so we don't support for
that for now.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <redacted>

---

Changes for v6:

 - Minor comment formatting fix
 - Add an additional check for CONFIG_TRANSPARENT_HUGEPAGE to fix a
   build breakage when CONFIG_PGTABLE_HAS_HUGE_LEAVES is not defined.

Changes for v5:

 - Fixed accounting as suggested by David.

Changes for v4:

 - New for v4, split out rmap changes as suggested by David.
---
 include/linux/rmap.h | 15 ++++++++++-
 mm/rmap.c            | 67 ++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 78 insertions(+), 4 deletions(-)

Looks mechanically correct to me.

Reviewed-by: Dan Williams <redacted>