[PATCH 15/16] page-flags: look on head page if the flag is encoded in page->mapping

[Kirill A. Shutemov]

PageAnon() and PageKsm() look on lower bits of page->mapping to check if
the page is Anon or KSM. page->mapping can be overloaded in tail pages.

Let's always look on head page to avoid false-positives.

Signed-off-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
---
 include/linux/page-flags.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 55a69c40e4ae..07fa2781df23 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -385,6 +385,7 @@ PAGEFLAG_FALSE(HWPoison)
 
 static inline int PageAnon(struct page *page)
 {
+       page = compound_head(page);
        return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
 }
 
@@ -397,6 +398,7 @@ static inline int PageAnon(struct page *page)
  */
 static inline int PageKsm(struct page *page)
 {
+       page = compound_head(page);
        return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
                                (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
 }
-- 
2.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/