From b3b3a99c5371e2e96a2c680e6ac20218bddbd422 Mon Sep 17 00:00:00 2001 From: Naoya Horiguchi Date: Wed, 15 Apr 2015 16:13:15 -0700 Subject: mm/migrate: check-before-clear PageSwapCache With the page flag sanitization patchset, an invalid usage of ClearPageSwapCache() is detected in migration_page_copy(). migrate_page_copy() is shared by both normal and hugepage (both thp and hugetlb) code path, so let's check PageSwapCache() and clear it if it's set to avoid misuse of the invalid clear operation. Signed-off-by: Naoya Horiguchi Acked-by: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/migrate.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/migrate.c b/mm/migrate.c index a65ff72ab739..f53838fe3dfe 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -537,7 +537,8 @@ void migrate_page_copy(struct page *newpage, struct page *page) * Please do not reorder this without considering how mm/ksm.c's * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache(). */ - ClearPageSwapCache(page); + if (PageSwapCache(page)) + ClearPageSwapCache(page); ClearPagePrivate(page); set_page_private(page, 0); -- cgit v1.2.3-58-ga151