[PATCHv4 02/24] mm: change PageAnon() and page_anon_vma() to work on tail pages

[Kirill A. Shutemov]

Currently PageAnon() and page_anon_vma() are always return false/NULL
for tail. We need to look on head page for correct answer.

Let's change the function to give the correct result for tail page.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 include/linux/mm.h   | 1 +
 include/linux/rmap.h | 1 +
 2 files changed, 2 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9c21b42d07bf..1aea94e837a0 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1047,6 +1047,7 @@ struct address_space *page_file_mapping(struct page *page)
 
 static inline int PageAnon(struct page *page)
 {
+	page = compound_head(page);
 	return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
 }
 
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 9c5ff69fa0cd..c4088feac1fc 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -108,6 +108,7 @@ static inline void put_anon_vma(struct anon_vma *anon_vma)
 
 static inline struct anon_vma *page_anon_vma(struct page *page)
 {
+	page = compound_head(page);
 	if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
 					    PAGE_MAPPING_ANON)
 		return NULL;
-- 
2.1.4

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