when I built with CONFIG_FAIR_GROUP_SCHED=y, I need the following change
to make things right.
[ From: mingo@elte.hu ]
this config option is not upstream-configurable right now but lets fix
this for completeness.
Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
  */
 static void set_curr_task_fair(struct rq *rq)
 {
-       struct sched_entity *se = &rq->curr.se;
+       struct sched_entity *se = &rq->curr->se;
 
        for_each_sched_entity(se)
                set_next_entity(cfs_rq_of(se), se);