diff --git a/include/linux/sched.h b/include/linux/sched.h
index b089c92c609b0a98e305513abb2485d5c9599fbd..9914c662ed7b5b581dd0ec8019cc6ba52365c922 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1778,12 +1778,6 @@ static inline int is_global_init(struct task_struct *tsk)
 	return tsk->pid == 1;
 }
 
-/*
- * is_container_init:
- * check whether in the task is init in its own pid namespace.
- */
-extern int is_container_init(struct task_struct *tsk);
-
 extern struct pid *cad_pid;
 
 extern void free_task(struct task_struct *tsk);
diff --git a/kernel/pid.c b/kernel/pid.c
index fd996c1ed9f891988607812abb95dc8820ab3751..a54a1123c7cf122a84f78da59944df34aff2a3a7 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -81,21 +81,6 @@ struct pid_namespace init_pid_ns = {
 };
 EXPORT_SYMBOL_GPL(init_pid_ns);
 
-int is_container_init(struct task_struct *tsk)
-{
-	int ret = 0;
-	struct pid *pid;
-
-	rcu_read_lock();
-	pid = task_pid(tsk);
-	if (pid != NULL && pid->numbers[pid->level].nr == 1)
-		ret = 1;
-	rcu_read_unlock();
-
-	return ret;
-}
-EXPORT_SYMBOL(is_container_init);
-
 /*
  * Note: disable interrupts while the pidmap_lock is held as an
  * interrupt might come in and do read_lock(&tasklist_lock).