• Mel Gorman's avatar
    Add __GFP_MOVABLE for callers to flag allocations from high memory that may be migrated · 769848c0
    Mel Gorman authored
    
    
    It is often known at allocation time whether a page may be migrated or not.
    This patch adds a flag called __GFP_MOVABLE and a new mask called
    GFP_HIGH_MOVABLE.  Allocations using the __GFP_MOVABLE can be either migrated
    using the page migration mechanism or reclaimed by syncing with backing
    storage and discarding.
    
    An API function very similar to alloc_zeroed_user_highpage() is added for
    __GFP_MOVABLE allocations called alloc_zeroed_user_highpage_movable().  The
    flags used by alloc_zeroed_user_highpage() are not changed because it would
    change the semantics of an existing API.  After this patch is applied there
    are no in-kernel users of alloc_zeroed_user_highpage() so it probably should
    be marked deprecated if this patch is merged.
    
    Note that this patch includes a minor cleanup to the use of __GFP_ZERO in
    shmem.c to keep all flag modifications to inode->mapping in the
    shmem_dir_alloc() helper function.  This clean-up suggestion is courtesy of
    Hugh Dickens.
    
    Additional credit goes to Christoph Lameter and Linus Torvalds for shaping the
    concept.  Credit to Hugh Dickens for catching issues with shmem swap vector
    and ramfs allocations.
    
    [akpm@linux-foundation.org: build fix]
    [hugh@veritas.com: __GFP_ZERO cleanup]
    Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
    Cc: Andy Whitcroft <apw@shadowen.org>
    Cc: Christoph Lameter <clameter@sgi.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    769848c0
page.h 2.67 KB