From 83467efbdb7948146581a56cbd683a22a0684bbb Mon Sep 17 00:00:00 2001 From: Naoya Horiguchi Date: Wed, 11 Sep 2013 14:22:11 -0700 Subject: 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 Cc: Andi Kleen Cc: Hillf Danton Cc: Wanpeng Li Cc: Mel Gorman Cc: Hugh Dickins Cc: KOSAKI Motohiro Cc: Michal Hocko Cc: Rik van Riel Cc: "Aneesh Kumar K.V" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/hugetlb.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'include/linux/hugetlb.h') diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 2e02c4ed1035..0393270466c3 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -381,6 +381,16 @@ static inline pgoff_t basepage_index(struct page *page) extern void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn); +int pmd_huge_support(void); +/* + * Currently hugepage migration is enabled only for pmd-based hugepage. + * This function will be updated when hugepage migration is more widely + * supported. + */ +static inline int hugepage_migration_support(struct hstate *h) +{ + return pmd_huge_support() && (huge_page_shift(h) == PMD_SHIFT); +} #else /* CONFIG_HUGETLB_PAGE */ struct hstate {}; @@ -409,6 +419,8 @@ static inline pgoff_t basepage_index(struct page *page) return page->index; } #define dissolve_free_huge_pages(s, e) do {} while (0) +#define pmd_huge_support() 0 +#define hugepage_migration_support(h) 0 #endif /* CONFIG_HUGETLB_PAGE */ #endif /* _LINUX_HUGETLB_H */ -- cgit v1.2.3