[PATCH] mm: use PageAnon() and PageKsm() helpers in page_anon_vma()

["Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>]

page_anon_vma() directly checks PAGE_MAPPING_ANON and PAGE_MAPPING_KSM
bits on page->mapping to find out if page->mapping is anon_vma;

Let's use PageAnon() and PageKsm() helpers instead. It helps readability
and makes page_anon_vma() work correctly on tail pages.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/rmap.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 9c5ff69fa0cd..21f10e53bb9e 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -108,8 +108,7 @@ static inline void put_anon_vma(struct anon_vma *anon_vma)
 
 static inline struct anon_vma *page_anon_vma(struct page *page)
 {
-	if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
-					    PAGE_MAPPING_ANON)
+	if (!PageAnon(page) || PageKsm(page))
 		return NULL;
 	return page_rmapping(page);
 }
-- 
2.1.4

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