diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index d581579..e12d928 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * include/linux/writeback.h
  */