mm: improve comment on page->mapping
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mapping is terse, and out of date (it does not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.
Link: http://lkml.kernel.org/r/20171220155552.15884-5-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
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 c2294e6..8c3b8ce 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -50,15 +50,9 @@
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 */