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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2013-09-11 14:22:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-11 15:57:49 -0700
commit83467efbdb7948146581a56cbd683a22a0684bbb (patch)
tree8faaf4d713adcfd5875190ee23f0218212838f24 /arch/arm
parentc8721bbbdd36382de51cd6b7a56322e0acca2414 (diff)
downloadlinux-linaro-stable-83467efbdb7948146581a56cbd683a22a0684bbb.tar.gz
mm: migrate: check movability of hugepage in unmap_and_move_huge_page()
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: Naoya 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/mm/hugetlbpage.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/arm/mm/hugetlbpage.c b/arch/arm/mm/hugetlbpage.c
index 66781bf34077..54ee6163c181 100644
--- a/arch/arm/mm/hugetlbpage.c
+++ b/arch/arm/mm/hugetlbpage.c
@@ -56,3 +56,8 @@ int pmd_huge(pmd_t pmd)
{
return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
}
+
+int pmd_huge_support(void)
+{
+ return 1;
+}