[PATCH 4/8] mm: Improve comment on page->mapping

[Matthew Wilcox <willy@infradead.org>]

From: Matthew Wilcox <mawilcox@microsoft.com>

The comment on page->mapping is terse, and out of date (it does not
mention the possibility of PAGE_MAPPING_MOVABLE).  Instead, point
the interested reader to page-flags.h where there is a much better
comment.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
 include/linux/mm_types.h | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index c2294e6204e8..8c3b8cea22ee 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -50,15 +50,9 @@ struct page {
 	unsigned long flags;		/* Atomic flags, some possibly
 					 * updated asynchronously */
 	union {
-		struct address_space *mapping;	/* If low bit clear, points to
-						 * inode address_space, or NULL.
-						 * If page mapped as anonymous
-						 * memory, low bit is set, and
-						 * it points to anon_vma object
-						 * or KSM private structure. See
-						 * PAGE_MAPPING_ANON and
-						 * PAGE_MAPPING_KSM.
-						 */
+		/* See page-flags.h for the definition of PAGE_MAPPING_FLAGS */
+		struct address_space *mapping;
+
 		void *s_mem;			/* slab first object */
 		atomic_t compound_mapcount;	/* first tail page */
 		/* page_deferred_list().next	 -- second tail page */
-- 
2.15.1

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