diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index bf97b09..db2c1df 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -103,6 +103,14 @@
  */
 unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
 
+/*
+ * Cleans the PTEs of shared mappings.
+ * (and since clean PTEs should also be readonly, write protects them too)
+ *
+ * returns the number of cleaned PTEs.
+ */
+int page_mkclean(struct page *);
+
 #else	/* !CONFIG_MMU */
 
 #define anon_vma_init()		do {} while (0)
@@ -112,6 +120,12 @@
 #define page_referenced(page,l) TestClearPageReferenced(page)
 #define try_to_unmap(page, refs) SWAP_FAIL
 
+static inline int page_mkclean(struct page *page)
+{
+	return 0;
+}
+
+
 #endif	/* CONFIG_MMU */
 
 /*