1 files changed, 55 insertions, 34 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0acf96b790c..415ab0268b5 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -139,6 +139,8 @@ void update_rq_clock(struct rq *rq)
 		return;
 
 	delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
+	if (delta < 0)
+		return;
 	rq->clock += delta;
 	update_rq_clock_task(rq, delta);
 }
@@ -243,6 +245,7 @@ sched_feat_write(struct file *filp, const char __user *ubuf,
 	char buf[64];
 	char *cmp;
 	int i;
+	struct inode *inode;
 
 	if (cnt > 63)
 		cnt = 63;
@@ -253,7 +256,11 @@ sched_feat_write(struct file *filp, const char __user *ubuf,
 	buf[cnt] = 0;
 	cmp = strstrip(buf);
 
+	/* Ensure the static_key remains in a consistent state */
+	inode = file_inode(filp);
+	mutex_lock(&inode->i_mutex);
 	i = sched_feat_set(cmp);
+	mutex_unlock(&inode->i_mutex);
 	if (i == __SCHED_FEAT_NR)
 		return -EINVAL;
 
@@ -587,30 +594,31 @@ static bool set_nr_if_polling(struct task_struct *p)
 #endif
 
 /*
- * resched_task - mark a task 'to be rescheduled now'.
+ * resched_curr - mark rq's current task 'to be rescheduled now'.
  *
  * On UP this means the setting of the need_resched flag, on SMP it
  * might also involve a cross-CPU call to trigger the scheduler on
  * the target CPU.
  */
-void resched_task(struct task_struct *p)
+void resched_curr(struct rq *rq)
 {
+	struct task_struct *curr = rq->curr;
 	int cpu;
 
-	lockdep_assert_held(&task_rq(p)->lock);
+	lockdep_assert_held(&rq->lock);
 
-	if (test_tsk_need_resched(p))
+	if (test_tsk_need_resched(curr))
 		return;
 
-	cpu = task_cpu(p);
+	cpu = cpu_of(rq);
 
 	if (cpu == smp_processor_id()) {
-		set_tsk_need_resched(p);
+		set_tsk_need_resched(curr);
 		set_preempt_need_resched();
 		return;
 	}
 
-	if (set_nr_and_not_polling(p))
+	if (set_nr_and_not_polling(curr))
 		smp_send_reschedule(cpu);
 	else
 		trace_sched_wake_idle_without_ipi(cpu);
@@ -623,7 +631,7 @@ void resched_cpu(int cpu)
 
 	if (!raw_spin_trylock_irqsave(&rq->lock, flags))
 		return;
-	resched_task(cpu_curr(cpu));
+	resched_curr(rq);
 	raw_spin_unlock_irqrestore(&rq->lock, flags);
 }
 
@@ -684,10 +692,16 @@ static void wake_up_idle_cpu(int cpu)
 
 static bool wake_up_full_nohz_cpu(int cpu)
 {
+	/*
+	 * We just need the target to call irq_exit() and re-evaluate
+	 * the next tick. The nohz full kick at least implies that.
+	 * If needed we can still optimize that later with an
+	 * empty IRQ.
+	 */
 	if (tick_nohz_full_cpu(cpu)) {
 		if (cpu != smp_processor_id() ||
 		    tick_nohz_tick_stopped())
-			smp_send_reschedule(cpu);
+			tick_nohz_full_kick_cpu(cpu);
 		return true;
 	}
 
@@ -730,18 +744,15 @@ static inline bool got_nohz_idle_kick(void)
 #ifdef CONFIG_NO_HZ_FULL
 bool sched_can_stop_tick(void)
 {
-       struct rq *rq;
-
-       rq = this_rq();
-
-       /* Make sure rq->nr_running update is visible after the IPI */
-       smp_rmb();
-
-       /* More than one running task need preemption */
-       if (rq->nr_running > 1)
-               return false;
+	/*
+	 * More than one running task need preemption.
+	 * nr_running update is assumed to be visible
+	 * after IPI is sent from wakers.
+	 */
+	if (this_rq()->nr_running > 1)
+		return false;
 
-       return true;
+	return true;
 }
 #endif /* CONFIG_NO_HZ_FULL */
 
@@ -1022,7 +1033,7 @@ void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
 			if (class == rq->curr->sched_class)
 				break;
 			if (class == p->sched_class) {
-				resched_task(rq->curr);
+				resched_curr(rq);
 				break;
 			}
 		}
@@ -1568,9 +1579,7 @@ void scheduler_ipi(void)
 	 */
 	preempt_fold_need_resched();
 
-	if (llist_empty(&this_rq()->wake_list)
-			&& !tick_nohz_full_cpu(smp_processor_id())
-			&& !got_nohz_idle_kick())
+	if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
 		return;
 
 	/*
@@ -1587,7 +1596,6 @@ void scheduler_ipi(void)
 	 * somewhat pessimize the simple resched case.
 	 */
 	irq_enter();
-	tick_nohz_full_check();
 	sched_ttwu_pending();
 
 	/*
@@ -2431,7 +2439,12 @@ static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
 {
 	u64 ns = 0;
 
-	if (task_current(rq, p)) {
+	/*
+	 * Must be ->curr _and_ ->on_rq.  If dequeued, we would
+	 * project cycles that may never be accounted to this
+	 * thread, breaking clock_gettime().
+	 */
+	if (task_current(rq, p) && p->on_rq) {
 		update_rq_clock(rq);
 		ns = rq_clock_task(rq) - p->se.exec_start;
 		if ((s64)ns < 0)
@@ -2474,8 +2487,10 @@ unsigned long long task_sched_runtime(struct task_struct *p)
 	 * If we race with it leaving cpu, we'll take a lock. So we're correct.
 	 * If we race with it entering cpu, unaccounted time is 0. This is
 	 * indistinguishable from the read occurring a few cycles earlier.
+	 * If we see ->on_cpu without ->on_rq, the task is leaving, and has
+	 * been accounted, so we're correct here as well.
 	 */
-	if (!p->on_cpu)
+	if (!p->on_cpu || !p->on_rq)
 		return p->se.sum_exec_runtime;
 #endif
 
@@ -2971,7 +2986,6 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
 	}
 
 	trace_sched_pi_setprio(p, prio);
-	p->pi_top_task = rt_mutex_get_top_task(p);
 	oldprio = p->prio;
 	prev_class = p->sched_class;
 	on_rq = p->on_rq;
@@ -2991,8 +3005,9 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
 	 *          running task
 	 */
 	if (dl_prio(prio)) {
-		if (!dl_prio(p->normal_prio) || (p->pi_top_task &&
-			dl_entity_preempt(&p->pi_top_task->dl, &p->dl))) {
+		struct task_struct *pi_task = rt_mutex_get_top_task(p);
+		if (!dl_prio(p->normal_prio) ||
+		    (pi_task && dl_entity_preempt(&pi_task->dl, &p->dl))) {
 			p->dl.dl_boosted = 1;
 			p->dl.dl_throttled = 0;
 			enqueue_flag = ENQUEUE_REPLENISH;
@@ -3064,7 +3079,7 @@ void set_user_nice(struct task_struct *p, long nice)
 		 * lowered its priority, then reschedule its CPU:
 		 */
 		if (delta < 0 || (delta > 0 && task_running(rq, p)))
-			resched_task(rq->curr);
+			resched_curr(rq);
 	}
 out_unlock:
 	task_rq_unlock(rq, p, &flags);
@@ -4286,7 +4301,7 @@ again:
 		 * fairness.
 		 */
 		if (preempt && rq != p_rq)
-			resched_task(p_rq->curr);
+			resched_curr(p_rq);
 	}
 
 out_unlock:
@@ -7093,7 +7108,7 @@ static void normalize_task(struct rq *rq, struct task_struct *p)
 	__setscheduler(rq, p, &attr);
 	if (on_rq) {
 		enqueue_task(rq, p, 0);
-		resched_task(rq->curr);
+		resched_curr(rq);
 	}
 
 	check_class_changed(rq, p, prev_class, old_prio);
@@ -7804,6 +7819,11 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
 	if (period > max_cfs_quota_period)
 		return -EINVAL;
 
+	/*
+	 * Prevent race between setting of cfs_rq->runtime_enabled and
+	 * unthrottle_offline_cfs_rqs().
+	 */
+	get_online_cpus();
 	mutex_lock(&cfs_constraints_mutex);
 	ret = __cfs_schedulable(tg, period, quota);
 	if (ret)
@@ -7829,7 +7849,7 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
 	}
 	raw_spin_unlock_irq(&cfs_b->lock);
 
-	for_each_possible_cpu(i) {
+	for_each_online_cpu(i) {
 		struct cfs_rq *cfs_rq = tg->cfs_rq[i];
 		struct rq *rq = cfs_rq->rq;
 
@@ -7845,6 +7865,7 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
 		cfs_bandwidth_usage_dec();
 out_unlock:
 	mutex_unlock(&cfs_constraints_mutex);
+	put_online_cpus();
 
 	return ret;
 }