diff --git a/[refs] b/[refs]
index e5966f54b842..2fe0392e6e60 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8e654fba4a376f436bdfe361fc5cdbc87ac09b35
+refs/heads/master: 6dda81f4384b94930826eded254d8c16f89a9248
diff --git a/trunk/include/linux/sched.h b/trunk/include/linux/sched.h
index b47c94e7560b..722dd313bf8a 100644
--- a/trunk/include/linux/sched.h
+++ b/trunk/include/linux/sched.h
@@ -1489,6 +1489,11 @@ static inline struct pid *task_tgid(struct task_struct *task)
 	return task->group_leader->pids[PIDTYPE_PID].pid;
 }
 
+/*
+ * Without tasklist or rcu lock it is not safe to dereference
+ * the result of task_pgrp/task_session even if task == current,
+ * we can race with another thread doing sys_setsid/sys_setpgid.
+ */
 static inline struct pid *task_pgrp(struct task_struct *task)
 {
 	return task->group_leader->pids[PIDTYPE_PGID].pid;