[PATCH 4/4] pagewalk: fix code comment for THP

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

commit bae9c19bf1 (thp: split_huge_page_mm/vma) changed locking behavior
of walk_page_range(). Thus this patch changes comment too.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
 mm/pagewalk.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index f792940..2f5cf10 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -176,7 +176,8 @@ static int walk_hugetlb_range(struct vm_area_struct *vma,
  * associated range, and a copy of the original mm_walk for access to
  * the ->private or ->mm fields.
  *
- * No locks are taken, but the bottom level iterator will map PTE
+ * Usually no locks are taken, but splitting transparent huge page may
+ * take page table lock. And the bottom level iterator will map PTE
  * directories from highmem if necessary.
  *
  * If any callback returns a non-zero value, the walk is aborted and
-- 
1.7.3.1