diff --git a/net/ceph/crush/hash.c b/net/ceph/crush/hash.c
index ed123af..e5cc603 100644
--- a/net/ceph/crush/hash.c
+++ b/net/ceph/crush/hash.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #ifdef __KERNEL__
 # include <linux/crush/hash.h>
 #else