diff --git a/mm/mmap.c b/mm/mmap.c
index 8840863..68a16b4 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -602,7 +602,7 @@
 	if (anon_vma) {
 		VM_BUG_ON(adjust_next && next->anon_vma &&
 			  anon_vma != next->anon_vma);
-		anon_vma_lock(anon_vma);
+		anon_vma_lock_write(anon_vma);
 		anon_vma_interval_tree_pre_update_vma(vma);
 		if (adjust_next)
 			anon_vma_interval_tree_pre_update_vma(next);