mm: Fix problem of parameter in note

'current' is a pointer, so the right form is  'down_write(&current->mm->mmap_sem)'.

Signed-off-by: Jianjun Kong <jianjun@zeuux.org>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/mmap.c b/mm/mmap.c
index 8101de4..26892e3 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -905,7 +905,7 @@
 #endif /* CONFIG_PROC_FS */
 
 /*
- * The caller must hold down_write(current->mm->mmap_sem).
+ * The caller must hold down_write(&current->mm->mmap_sem).
  */
 
 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,