[PATCHv3 02/24] mm: change PageAnon() and page_anon_vma() to work on tail pages

Kirill A. Shutemov
2015-02-12T16:18:58Z

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@linux.intel.com>
---
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 47a93928b90f..9071066b7c2e 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