diff --git a/mm/rmap.c b/mm/rmap.c
index 7eab4ed..5a79bf5 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1684,6 +1684,24 @@
 }
 
 #ifdef CONFIG_MIGRATION
+static struct anon_vma *rmap_walk_anon_lock(struct page *page)
+{
+	struct anon_vma *anon_vma;
+
+	/*
+	 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
+	 * because that depends on page_mapped(); but not all its usages
+	 * are holding mmap_sem. Users without mmap_sem are required to
+	 * take a reference count to prevent the anon_vma disappearing
+	 */
+	anon_vma = page_anon_vma(page);
+	if (!anon_vma)
+		return NULL;
+
+	anon_vma_lock_read(anon_vma);
+	return anon_vma;
+}
+
 /*
  * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():
  * Called by migrate.c to remove migration ptes, but might be used more later.
@@ -1696,16 +1714,10 @@
 	struct anon_vma_chain *avc;
 	int ret = SWAP_AGAIN;
 
-	/*
-	 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
-	 * because that depends on page_mapped(); but not all its usages
-	 * are holding mmap_sem. Users without mmap_sem are required to
-	 * take a reference count to prevent the anon_vma disappearing
-	 */
-	anon_vma = page_anon_vma(page);
+	anon_vma = rmap_walk_anon_lock(page);
 	if (!anon_vma)
 		return ret;
-	anon_vma_lock_read(anon_vma);
+
 	anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
 		struct vm_area_struct *vma = avc->vma;
 		unsigned long address = vma_address(page, vma);