diff --git a/include/linux/sched.h b/include/linux/sched.h
index 33e4e9e1f621..66a17ad55bcb 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2295,8 +2295,6 @@ extern struct mm_struct *get_task_mm(struct task_struct *task);
 extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
 /* Remove the current tasks stale references to the old mm_struct */
 extern void mm_release(struct task_struct *, struct mm_struct *);
-/* Allocate a new mm structure and copy contents from tsk->mm */
-extern struct mm_struct *dup_mm(struct task_struct *tsk);
 
 extern int copy_thread(unsigned long, unsigned long, unsigned long,
 			struct task_struct *);
diff --git a/kernel/fork.c b/kernel/fork.c
index 2f11bbe376b0..5615ead014e3 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -800,7 +800,7 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm)
  * Allocate a new mm structure and copy contents from the
  * mm structure of the passed in task structure.
  */
-struct mm_struct *dup_mm(struct task_struct *tsk)
+static struct mm_struct *dup_mm(struct task_struct *tsk)
 {
 	struct mm_struct *mm, *oldmm = current->mm;
 	int err;