diff --git a/kernel/cpu.c b/kernel/cpu.c
index da31165..306844e 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -180,7 +180,7 @@
 };
 
 /* Take this CPU down. */
-static int take_cpu_down(void *_param)
+static int __ref take_cpu_down(void *_param)
 {
 	struct take_cpu_down_param *param = _param;
 	int err;
@@ -199,7 +199,7 @@
 }
 
 /* Requires cpu_add_remove_lock to be held */
-static int _cpu_down(unsigned int cpu, int tasks_frozen)
+static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
 {
 	int err, nr_calls = 0;
 	struct task_struct *p;
@@ -274,7 +274,7 @@
 	return err;
 }
 
-int cpu_down(unsigned int cpu)
+int __ref cpu_down(unsigned int cpu)
 {
 	int err = 0;