mm/hugepage pud: allow arch-specific helper function to check huge page pud support

Patch series "Add support for DAX vmemmap optimization for ppc64", v6.

This patch series implements changes required to support DAX vmemmap
optimization for ppc64.  The vmemmap optimization is only enabled with
radix MMU translation and 1GB PUD mapping with 64K page size.

The patch series also splits the hugetlb vmemmap optimization as a
separate Kconfig variable so that architectures can enable DAX vmemmap
optimization without enabling hugetlb vmemmap optimization.  This should
enable architectures like arm64 to enable DAX vmemmap optimization while
they can't enable hugetlb vmemmap optimization.  More details of the same
are in patch "mm/vmemmap optimization: Split hugetlb and devdax vmemmap
optimization".

With 64K page size for 16384 pages added (1G) we save 14 pages
With 4K page size for 262144 pages added (1G) we save 4094 pages
With 4K page size for 512 pages added (2M) we save 6 pages


This patch (of 13):

Architectures like powerpc would like to enable transparent huge page pud
support only with radix translation.  To support that add
has_transparent_pud_hugepage() helper that architectures can override.

[[email protected]: use the new has_transparent_pud_hugepage()]
  Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Aneesh Kumar K.V <[email protected]>
Reviewed-by: Christophe Leroy <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Joao Martins <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions