• Naoya Horiguchi's avatar
    mm: migrate: check movability of hugepage in unmap_and_move_huge_page() · 83467efb
    Naoya Horiguchi authored
    Currently hugepage migration works well only for pmd-based hugepages
    (mainly due to lack of testing,) so we had better not enable migration of
    other levels of hugepages until we are ready for it.
    Some users of hugepage migration (mbind, move_pages, and migrate_pages) do
    page table walk and check pud/pmd_huge() there, so they are safe.  But the
    other users (softoffline and memory hotremove) don't do this, so without
    this patch they can try to migrate unexpected types of hugepages.
    To prevent this, we introduce hugepage_migration_support() as an
    architecture dependent check of whether hugepage are implemented on a pmd
    basis or not.  And on some architecture multiple sizes of hugepages are
    available, so hugepage_migration_support() also checks hugepage size.
    Signed-off-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: Hillf Danton <dhillf@gmail.com>
    Cc: Wanpeng Li <liwanp@linux.vnet.ibm.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>
hugetlbpage.c 9.68 KB