mm: update comments for struct page.mapping

struct page.mapping can be NULL or points to one object of type
address_space, anon_vma or KSM private structure.

Link: http://lkml.kernel.org/r/1506485067-15954-1-git-send-email-changbin.du@intel.com
Signed-off-by: Changbin Du <changbin.du@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index c85f11d..d1b8e8f 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -48,8 +48,10 @@ struct page {
                                                 * inode address_space, or NULL.
                                                 * If page mapped as anonymous
                                                 * memory, low bit is set, and
-                                                * it points to anon_vma object:
-                                                * see PAGE_MAPPING_ANON below.
+                                                * it points to anon_vma object
+                                                * or KSM private structure. See
+                                                * PAGE_MAPPING_ANON and
+                                                * PAGE_MAPPING_KSM.
                                                 */
                void *s_mem;                    /* slab first object */
                atomic_t compound_mapcount;     /* first tail page */