kernel/fork.c: make dup_mm() static

dup_mm() is used only in kernel/fork.c

Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/fork.c b/kernel/fork.c
index 2f11bbe..5615ead 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -800,7 +800,7 @@
  * 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;