[PATCH 3/9] powerpc/mm: Add _PAGE_DEVMAP for ppc64.

[Aneesh Kumar K.V]

Oliver O'Halloran <oohall at gmail.com> writes:

> From: "Aneesh Kumar K.V" <aneesh.kumar at linux.vnet.ibm.com>
>
> Add a _PAGE_DEVMAP bit for PTE and DAX PMD entires. PowerPC doesn't
> currently support PUD faults so we haven't extended it to the PUD
> level.
>
> Cc: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
> Signed-off-by: Oliver O'Halloran <oohall at gmail.com>


Few changes we would need. We will now need to make sure a devmap
pmd entry is not confused with THP. ie,

we should compare against _PAGE_PTE and _PAGE_DEVMAP in
pmd_trans_huge(). hash already has one bit we use to differentiate
between hugetlb and THP. May be we can genarlize this and come up with a
way to differentiate THP, HUGETLB,pmd DEVMAP entries ?


also I don't see you handing get_user_pages_fast() ?


-aneesh