mm: differentiate page_mapped() from page_mapcount() for compound pages

[karo-tx-linux.git] / include / linux / mm.h

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 67e0fab225e8bf68c04dc9c0e07d7ef3d2e49595..6b56cfd9fd09191ecdc4efdf09f968a0ac38f4e0 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -953,10 +953,21 @@ static inline pgoff_t page_file_index(struct page *page)
 
 /*
  * Return true if this page is mapped into pagetables.
+ * For compound page it returns true if any subpage of compound page is mapped.
  */
-static inline int page_mapped(struct page *page)
+static inline bool page_mapped(struct page *page)
 {
-       return atomic_read(&(page)->_mapcount) + compound_mapcount(page) >= 0;
+       int i;
+       if (likely(!PageCompound(page)))
+               return atomic_read(&page->_mapcount) >= 0;
+       page = compound_head(page);
+       if (atomic_read(compound_mapcount_ptr(page)) >= 0)
+               return true;
+       for (i = 0; i < hpage_nr_pages(page); i++) {
+               if (atomic_read(&page[i]._mapcount) >= 0)
+                       return true;
+       }
+       return false;
 }
 
 /*