1 files changed, 36 insertions, 5 deletions

diff --git a/mm/util.c b/mm/util.c
index 3981ae9d1b15..68ff8a5361e7 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -325,9 +325,37 @@ void kvfree(const void *addr)
 }
 EXPORT_SYMBOL(kvfree);
 
+static inline void *__page_rmapping(struct page *page)
+{
+        unsigned long mapping;
+
+        mapping = (unsigned long)page->mapping;
+        mapping &= ~PAGE_MAPPING_FLAGS;
+
+        return (void *)mapping;
+}
+
+/* Neutral page->mapping pointer to address_space or anon_vma or other */
+void *page_rmapping(struct page *page)
+{
+        page = compound_head(page);
+        return __page_rmapping(page);
+}
+
+struct anon_vma *page_anon_vma(struct page *page)
+{
+        unsigned long mapping;
+
+        page = compound_head(page);
+        mapping = (unsigned long)page->mapping;
+        if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
+                return NULL;
+        return __page_rmapping(page);
+}
+
 struct address_space *page_mapping(struct page *page)
 {
-        struct address_space *mapping = page->mapping;
+        unsigned long mapping;
 
         /* This happens if someone calls flush_dcache_page on slab page */
         if (unlikely(PageSlab(page)))
@@ -337,10 +365,13 @@ struct address_space *page_mapping(struct page *page)
                 swp_entry_t entry;
 
                 entry.val = page_private(page);
-                mapping = swap_address_space(entry);
-        } else if ((unsigned long)mapping & PAGE_MAPPING_ANON)
-                mapping = NULL;
-        return mapping;
+                return swap_address_space(entry);
+        }
+
+        mapping = (unsigned long)page->mapping;
+        if (mapping & PAGE_MAPPING_FLAGS)
+                return NULL;
+        return page->mapping;
 }
 
 int overcommit_ratio_handler(struct ctl_table *table, int write,