--- x/mm/mempolicy.c
+++ y/mm/mempolicy.c
@@ -1342,6 +1342,7 @@ static long do_mbind(unsigned long start
 	vma_iter_init(&vmi, mm, start);
 	prev = vma_prev(&vmi);
 	for_each_vma_range(vmi, vma, end) {
+		vma_start_write(vma);
 		err = mbind_range(&vmi, vma, &prev, start, end, new);
 		if (err)
 			break;