• Mel Gorman's avatar
    mm: remove misleading ARCH_USES_NUMA_PROT_NONE · 6a33979d
    Mel Gorman authored
    ARCH_USES_NUMA_PROT_NONE was defined for architectures that implemented
    _PAGE_NUMA using _PROT_NONE.  This saved using an additional PTE bit and
    relied on the fact that PROT_NONE vmas were skipped by the NUMA hinting
    fault scanner.  This was found to be conceptually confusing with a lot of
    implicit assumptions and it was asked that an alternative be found.
    
    Commit c46a7c81 "x86: define _PAGE_NUMA by reusing software bits on the
    PMD and PTE levels" redefined _PAGE_NUMA on x86 to be one of the swap PTE
    bits and shrunk the maximum possible swap size but it did not go far
    enough.  There are no architectures that reuse _PROT_NONE as _PROT_NUMA
    but the relics still exist.
    
    This patch removes ARCH_USES_NUMA_PROT_NONE and removes some unnecessary
    duplication in powerpc vs the generic implementation by defining the types
    the core NUMA helpers expected to exist from x86 with their ppc64
    equivalent.  This necessitated that a PTE bit mask be created that
    identified the bits that distinguish present from NUMA pte entries but it
    is expected this will only differ between arches based on _PAGE_PROTNONE.
    The naming for the generic helpers was taken from x86 originally but ppc64
    has types that are equivalent for the purposes of the helper so they are
    mapped instead of duplicating code.
    Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
    Cc: Hugh Dickins <hughd@google.com>
    Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Cyrill Gorcunov <gorcunov@gmail.com>
    Reviewed-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    6a33979d
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