diff --git a/[refs] b/[refs]
index 169cf245d6b6..194c3de94270 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3da367c3e5fca71d4e778fa565d9b098d5518f4a
+refs/heads/master: d08c429b06d21bd2add88aea2cd1996f1b9b3bda
diff --git a/trunk/mm/page-writeback.c b/trunk/mm/page-writeback.c
index 0e309cd1b5b9..793e9874de51 100644
--- a/trunk/mm/page-writeback.c
+++ b/trunk/mm/page-writeback.c
@@ -305,7 +305,9 @@ static unsigned long task_min_dirty_limit(unsigned long bdi_dirty)
 }
 
 /*
- *
+ * bdi_min_ratio keeps the sum of the minimum dirty shares of all
+ * registered backing devices, which, for obvious reasons, can not
+ * exceed 100%.
  */
 static unsigned int bdi_min_ratio;