• Naoya Horiguchi's avatar
    mm: migrate: make core migration code aware of hugepage · 31caf665
    Naoya Horiguchi authored
    Currently hugepage migration is available only for soft offlining, but
    it's also useful for some other users of page migration (clearly because
    users of hugepage can enjoy the benefit of mempolicy and memory hotplug.)
    So this patchset tries to extend such users to support hugepage migration.
    The target of this patchset is to enable hugepage migration for NUMA
    related system calls (migrate_pages(2), move_pages(2), and mbind(2)), and
    memory hotplug.
    This patchset does not add hugepage migration for memory compaction,
    because users of memory compaction mainly expect to construct thp by
    arranging raw pages, and there's little or no need to compact hugepages.
    CMA, another user of page migration, can have benefit from hugepage
    migration, but is not enabled to support it for now (just because of lack
    of testing and expertise in CMA.)
    Hugepage migration of non pmd-based hugepage (for example 1GB hugepage in
    x86_64, or hugepages in architectures like ia64) is not enabled for now
    (again, because of lack of testing.)
    As for how these are achived, I extended the API (migrate_pages()) to
    handle hugepage (with patch 1 and 2) and adjusted code of each caller to
    check and collect movable hugepages (with patch 3-7).  Remaining 2 patches
    are kind of miscellaneous ones to avoid unexpected behavior.  Patch 8 is
    about making sure that we only migrate pmd-based hugepages.  And patch 9
    is about choosing appropriate zone for hugepage allocation.
    My test is mainly functional one, simply kicking hugepage migration via
    each entry point and confirm that migration is done correctly.  Test code
    is available here:
    And I always run libhugetlbfs test when changing hugetlbfs's code.  With
    this patchset, no regression was found in the test.
    This patch (of 9):
    Before enabling each user of page migration to support hugepage,
    this patch enables the list of pages for migration to link not only
    LRU pages, but also hugepages. As a result, putback_movable_pages()
    and migrate_pages() can handle both of LRU pages and hugepages.
    Signed-off-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
    Acked-by: default avatarAndi Kleen <ak@linux.intel.com>
    Reviewed-by: default avatarWanpeng Li <liwanp@linux.vnet.ibm.com>
    Acked-by: default avatarHillf Danton <dhillf@gmail.com>
    Cc: Mel Gorman <mgorman@suse.de>
    Cc: Hugh Dickins <hughd@google.com>
    Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Cc: Michal Hocko <mhocko@suse.cz>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: "Aneesh 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>
hugetlb.h 10.9 KB