--- x/mm/vma.c
+++ y/mm/vma.c
@@ -1263,11 +1263,12 @@ static void vms_complete_munmap_vmas(str
 	mm = current->mm;
 	mm->map_count -= vms->vma_count;
 	mm->locked_vm -= vms->locked_vm;
-	if (vms->unlock)
-		mmap_write_downgrade(mm);
 
-	if (!vms->nr_pages)
+	if (!vms->nr_pages) {
+		if (vms->unlock)
+			mmap_write_unlock(mm);
 		return;
+	}
 
 	vms_clear_ptes(vms, mas_detach, !vms->unlock);
 	/* Update high watermark before we lower total_vm */
@@ -1284,13 +1285,15 @@ static void vms_complete_munmap_vmas(str
 
 	/* Remove and clean up vmas */
 	mas_set(mas_detach, 0);
-	mas_for_each(mas_detach, vma, ULONG_MAX)
+	mas_for_each(mas_detach, vma, ULONG_MAX) {
+		vma_start_write(vma);
 		remove_vma(vma);
+	}
 
 	vm_unacct_memory(vms->nr_accounted);
 	validate_mm(mm);
 	if (vms->unlock)
-		mmap_read_unlock(mm);
+		mmap_write_unlock(mm);
 
 	__mt_destroy(mas_detach->tree);
 }