diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 89f0564..3593b18 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -63,9 +63,6 @@
 void anon_vma_link(struct vm_area_struct *);
 void __anon_vma_link(struct vm_area_struct *);
 
-extern struct anon_vma *page_lock_anon_vma(struct page *page);
-extern void page_unlock_anon_vma(struct anon_vma *anon_vma);
-
 /*
  * rmap interfaces called when adding or removing pte of page
  */
diff --git a/mm/rmap.c b/mm/rmap.c
index 10da682..892e187 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -193,7 +193,7 @@
  * Getting a lock on a stable anon_vma from a page off the LRU is
  * tricky: page_lock_anon_vma rely on RCU to guard against the races.
  */
-struct anon_vma *page_lock_anon_vma(struct page *page)
+static struct anon_vma *page_lock_anon_vma(struct page *page)
 {
 	struct anon_vma *anon_vma;
 	unsigned long anon_mapping;
@@ -213,7 +213,7 @@
 	return NULL;
 }
 
-void page_unlock_anon_vma(struct anon_vma *anon_vma)
+static void page_unlock_anon_vma(struct anon_vma *anon_vma)
 {
 	spin_unlock(&anon_vma->lock);
 	rcu_read_unlock();