Automatically merging tracking-igloo_kernel-other into merging-stable-linaro-ux500-3.1stable-linaro-ux500-3.1

Conflicting files:

1 files changed, 17 insertions, 4 deletions

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 774b8952deb..10a2f62cd56 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -62,10 +62,23 @@ struct page {
 			struct {
 
 				union {
-					atomic_t _mapcount;	/* Count of ptes mapped in mms,
-							 * to show when page is mapped
-							 * & limit reverse map searches.
-							 */
+					/*
+					 * Count of ptes mapped in
+					 * mms, to show when page is
+					 * mapped & limit reverse map
+					 * searches.
+					 *
+					 * Used also for tail pages
+					 * refcounting instead of
+					 * _count. Tail pages cannot
+					 * be mapped and keeping the
+					 * tail page _count zero at
+					 * all times guarantees
+					 * get_page_unless_zero() will
+					 * never succeed on tail
+					 * pages.
+					 */
+					atomic_t _mapcount;
 
 					struct {
 						unsigned inuse:16;