shmem: get_unmapped_area align huge page

[cascardo/linux.git] / mm / util.c

diff --git a/mm/util.c b/mm/util.c
index 917e0e3..8d010ef 100644 (file)
--- a/mm/util.c
+++ b/mm/util.c
@@ -399,10 +399,12 @@ struct address_space *page_mapping(struct page *page)
        }
 
        mapping = page->mapping;
-       if ((unsigned long)mapping & PAGE_MAPPING_FLAGS)
+       if ((unsigned long)mapping & PAGE_MAPPING_ANON)
                return NULL;
-       return mapping;
+
+       return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS);
 }
+EXPORT_SYMBOL(page_mapping);
 
 /* Slow path of page_mapcount() for compound pages */
 int __page_mapcount(struct page *page)
@@ -410,6 +412,12 @@ int __page_mapcount(struct page *page)
        int ret;
 
        ret = atomic_read(&page->_mapcount) + 1;
+       /*
+        * For file THP page->_mapcount contains total number of mapping
+        * of the page: no need to look into compound_mapcount.
+        */
+       if (!PageAnon(page) && !PageHuge(page))
+               return ret;
        page = compound_head(page);
        ret += atomic_read(compound_mapcount_ptr(page)) + 1;
        if (PageDoubleMap(page))