sched: Reinit task's vruntime if a task sleep over 200 days

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I67BL1
CVE: NA

-------------------------------

If a task sleep for long time, it maybe cause a s64 overflow
issue at max_vruntime() and the task will be set an incorrect
vruntime, lead to the task be starve.

For fix it, we set the task's vruntime as cfs_rq->min_vruntime
when wakeup.
Signed-off-by: NZhang Qiao <zhangqiao22@huawei.com>
Reviewed-by: NChen Hui <judy.chenhui@huawei.com>
Reviewed-by: Nsongping yu <yusongping@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

kernel/sched/fair.c

@@ -3949,10 +3949,14 @@ static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
 #endif
 }
 
+/* The threshold when the wakee's vruntime should be set cfs_rq->min_vruntime, default: 200 days */
+#define WAKEUP_REINIT_THRESHOLD_NS     (200 * 24 * 3600 * NSEC_PER_SEC)
+
 static void
 place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
 {
 	u64 vruntime = cfs_rq->min_vruntime;
+	struct rq *rq = rq_of(cfs_rq);
 
 	/*
 	 * The 'current' period is already promised to the current tasks,
@@ -3977,8 +3981,11 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
 		vruntime -= thresh;
 	}
 
+	if (unlikely(!initial && (s64)(rq_clock_task(rq) - se->exec_start) > WAKEUP_REINIT_THRESHOLD_NS))
+		se->vruntime = vruntime;
+	else
 	/* ensure we never gain time by being placed backwards. */
-	se->vruntime = max_vruntime(se->vruntime, vruntime);
+		se->vruntime = max_vruntime(se->vruntime, vruntime);
 }
 
 static void check_enqueue_throttle(struct cfs_rq *cfs_rq);