diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 01fbae5..695f0c6 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -307,6 +307,7 @@
  * @cpu: cpu to stop
  * @fn: function to execute
  * @arg: argument to @fn
+ * @work_buf: pointer to cpu_stop_work structure
  *
  * Similar to stop_one_cpu() but doesn't wait for completion.  The
  * caller is responsible for ensuring @work_buf is currently unused