1 files changed, 350 insertions, 127 deletions

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 8ec86abe0ea1..4184d4a97fd2 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -7,6 +7,10 @@
 
 #include <linux/slab.h>
 #include <linux/irq_work.h>
+#include <linux/hrtimer.h>
+
+#include "walt.h"
+#include "tune.h"
 
 int sched_rr_timeslice = RR_TIMESLICE;
 
@@ -64,10 +68,6 @@ static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
 	raw_spin_unlock(&rt_b->rt_runtime_lock);
 }
 
-#if defined(CONFIG_SMP) && defined(HAVE_RT_PUSH_IPI)
-static void push_irq_work_func(struct irq_work *work);
-#endif
-
 void init_rt_rq(struct rt_rq *rt_rq)
 {
 	struct rt_prio_array *array;
@@ -87,13 +87,6 @@ void init_rt_rq(struct rt_rq *rt_rq)
 	rt_rq->rt_nr_migratory = 0;
 	rt_rq->overloaded = 0;
 	plist_head_init(&rt_rq->pushable_tasks);
-
-#ifdef HAVE_RT_PUSH_IPI
-	rt_rq->push_flags = 0;
-	rt_rq->push_cpu = nr_cpu_ids;
-	raw_spin_lock_init(&rt_rq->push_lock);
-	init_irq_work(&rt_rq->push_work, push_irq_work_func);
-#endif
 #endif /* CONFIG_SMP */
 	/* We start is dequeued state, because no RT tasks are queued */
 	rt_rq->rt_queued = 0;
@@ -833,6 +826,8 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
 		struct rq *rq = rq_of_rt_rq(rt_rq);
 
 		raw_spin_lock(&rq->lock);
+		update_rq_clock(rq);
+
 		if (rt_rq->rt_time) {
 			u64 runtime;
 
@@ -889,6 +884,51 @@ static inline int rt_se_prio(struct sched_rt_entity *rt_se)
 	return rt_task_of(rt_se)->prio;
 }
 
+static void dump_throttled_rt_tasks(struct rt_rq *rt_rq)
+{
+	struct rt_prio_array *array = &rt_rq->active;
+	struct sched_rt_entity *rt_se;
+	char buf[500];
+	char *pos = buf;
+	char *end = buf + sizeof(buf);
+	int idx;
+
+	pos += snprintf(pos, sizeof(buf),
+		"sched: RT throttling activated for rt_rq %p (cpu %d)\n",
+		rt_rq, cpu_of(rq_of_rt_rq(rt_rq)));
+
+	if (bitmap_empty(array->bitmap, MAX_RT_PRIO))
+		goto out;
+
+	pos += snprintf(pos, end - pos, "potential CPU hogs:\n");
+	idx = sched_find_first_bit(array->bitmap);
+	while (idx < MAX_RT_PRIO) {
+		list_for_each_entry(rt_se, array->queue + idx, run_list) {
+			struct task_struct *p;
+
+			if (!rt_entity_is_task(rt_se))
+				continue;
+
+			p = rt_task_of(rt_se);
+			if (pos < end)
+				pos += snprintf(pos, end - pos, "\t%s (%d)\n",
+					p->comm, p->pid);
+		}
+		idx = find_next_bit(array->bitmap, MAX_RT_PRIO, idx + 1);
+	}
+out:
+#ifdef CONFIG_PANIC_ON_RT_THROTTLING
+	/*
+	 * Use pr_err() in the BUG() case since printk_sched() will
+	 * not get flushed and deadlock is not a concern.
+	 */
+	pr_err("%s", buf);
+	BUG();
+#else
+	printk_deferred("%s", buf);
+#endif
+}
+
 static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
 {
 	u64 runtime = sched_rt_runtime(rt_rq);
@@ -912,8 +952,14 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
 		 * but accrue some time due to boosting.
 		 */
 		if (likely(rt_b->rt_runtime)) {
+			static bool once = false;
+
 			rt_rq->rt_throttled = 1;
-			printk_deferred_once("sched: RT throttling activated\n");
+
+			if (!once) {
+				once = true;
+				dump_throttled_rt_tasks(rt_rq);
+			}
 		} else {
 			/*
 			 * In case we did anyway, make it go away,
@@ -932,6 +978,70 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
 	return 0;
 }
 
+#define RT_SCHEDTUNE_INTERVAL 50000000ULL
+
+static enum hrtimer_restart rt_schedtune_timer(struct hrtimer *timer)
+{
+	struct sched_rt_entity *rt_se = container_of(timer,
+			struct sched_rt_entity,
+			schedtune_timer);
+	struct task_struct *p = rt_task_of(rt_se);
+	struct rq *rq = task_rq(p);
+
+	raw_spin_lock(&rq->lock);
+
+	/*
+	 * Nothing to do if:
+	 * - task has switched runqueues
+	 * - task isn't RT anymore
+	 */
+	if (rq != task_rq(p) || (p->sched_class != &rt_sched_class))
+		goto out;
+
+	/*
+	 * If task got enqueued back during callback time, it means we raced
+	 * with the enqueue on another cpu, that's Ok, just do nothing as
+	 * enqueue path would have tried to cancel us and we shouldn't run
+	 * Also check the schedtune_enqueued flag as class-switch on a
+	 * sleeping task may have already canceled the timer and done dq
+	 */
+	if (p->on_rq || !rt_se->schedtune_enqueued)
+		goto out;
+
+	/*
+	 * RT task is no longer active, cancel boost
+	 */
+	rt_se->schedtune_enqueued = false;
+	schedtune_dequeue_task(p, cpu_of(rq));
+	cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_RT);
+out:
+	raw_spin_unlock(&rq->lock);
+
+	/*
+	 * This can free the task_struct if no more references.
+	 */
+	put_task_struct(p);
+
+	return HRTIMER_NORESTART;
+}
+
+void init_rt_schedtune_timer(struct sched_rt_entity *rt_se)
+{
+	struct hrtimer *timer = &rt_se->schedtune_timer;
+
+	hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	timer->function = rt_schedtune_timer;
+	rt_se->schedtune_enqueued = false;
+}
+
+static void start_schedtune_timer(struct sched_rt_entity *rt_se)
+{
+	struct hrtimer *timer = &rt_se->schedtune_timer;
+
+	hrtimer_start(timer, ns_to_ktime(RT_SCHEDTUNE_INTERVAL),
+			HRTIMER_MODE_REL_PINNED);
+}
+
 /*
  * Update the current task's runtime statistics. Skip current tasks that
  * are not in our scheduling class.
@@ -949,6 +1059,9 @@ static void update_curr_rt(struct rq *rq)
 	if (unlikely((s64)delta_exec <= 0))
 		return;
 
+	/* Kick cpufreq (see the comment in kernel/sched/sched.h). */
+	cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_RT);
+
 	schedstat_set(curr->se.statistics.exec_max,
 		      max(curr->se.statistics.exec_max, delta_exec));
 
@@ -1261,9 +1374,37 @@ enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
 		rt_se->timeout = 0;
 
 	enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
+	walt_inc_cumulative_runnable_avg(rq, p);
 
 	if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
 		enqueue_pushable_task(rq, p);
+
+	if (!schedtune_task_boost(p))
+		return;
+
+	/*
+	 * If schedtune timer is active, that means a boost was already
+	 * done, just cancel the timer so that deboost doesn't happen.
+	 * Otherwise, increase the boost. If an enqueued timer was
+	 * cancelled, put the task reference.
+	 */
+	if (hrtimer_try_to_cancel(&rt_se->schedtune_timer) == 1)
+		put_task_struct(p);
+
+	/*
+	 * schedtune_enqueued can be true in the following situation:
+	 * enqueue_task_rt grabs rq lock before timer fires
+	 *    or before its callback acquires rq lock
+	 * schedtune_enqueued can be false if timer callback is running
+	 * and timer just released rq lock, or if the timer finished
+	 * running and canceling the boost
+	 */
+	if (rt_se->schedtune_enqueued)
+		return;
+
+	rt_se->schedtune_enqueued = true;
+	schedtune_enqueue_task(p, cpu_of(rq));
+	cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_RT);
 }
 
 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
@@ -1272,8 +1413,22 @@ static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
 
 	update_curr_rt(rq);
 	dequeue_rt_entity(rt_se);
+	walt_dec_cumulative_runnable_avg(rq, p);
 
 	dequeue_pushable_task(rq, p);
+
+	if (!rt_se->schedtune_enqueued)
+		return;
+
+	if (flags == DEQUEUE_SLEEP) {
+		get_task_struct(p);
+		start_schedtune_timer(rt_se);
+		return;
+	}
+
+	rt_se->schedtune_enqueued = false;
+	schedtune_dequeue_task(p, cpu_of(rq));
+	cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_RT);
 }
 
 /*
@@ -1313,8 +1468,35 @@ static void yield_task_rt(struct rq *rq)
 #ifdef CONFIG_SMP
 static int find_lowest_rq(struct task_struct *task);
 
+/*
+ * Perform a schedtune dequeue and cancelation of boost timers if needed.
+ * Should be called only with the rq->lock held.
+ */
+static void schedtune_dequeue_rt(struct rq *rq, struct task_struct *p)
+{
+	struct sched_rt_entity *rt_se = &p->rt;
+
+	BUG_ON(!raw_spin_is_locked(&rq->lock));
+
+	if (!rt_se->schedtune_enqueued)
+		return;
+
+	/*
+	 * Incase of class change cancel any active timers. If an enqueued
+	 * timer was cancelled, put the task ref.
+	 */
+	if (hrtimer_try_to_cancel(&rt_se->schedtune_timer) == 1)
+		put_task_struct(p);
+
+	/* schedtune_enqueued is true, deboost it */
+	rt_se->schedtune_enqueued = false;
+	schedtune_dequeue_task(p, task_cpu(p));
+	cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_RT);
+}
+
 static int
-select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
+select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags,
+		  int sibling_count_hint)
 {
 	struct task_struct *curr;
 	struct rq *rq;
@@ -1366,6 +1548,19 @@ select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
 	rcu_read_unlock();
 
 out:
+	/*
+	 * If previous CPU was different, make sure to cancel any active
+	 * schedtune timers and deboost.
+	 */
+	if (task_cpu(p) != cpu) {
+		unsigned long fl;
+		struct rq *prq = task_rq(p);
+
+		raw_spin_lock_irqsave(&prq->lock, fl);
+		schedtune_dequeue_rt(prq, p);
+		raw_spin_unlock_irqrestore(&prq->lock, fl);
+	}
+
 	return cpu;
 }
 
@@ -1780,7 +1975,9 @@ retry:
 	}
 
 	deactivate_task(rq, next_task, 0);
+	next_task->on_rq = TASK_ON_RQ_MIGRATING;
 	set_task_cpu(next_task, lowest_rq->cpu);
+	next_task->on_rq = TASK_ON_RQ_QUEUED;
 	activate_task(lowest_rq, next_task, 0);
 	ret = 1;
 
@@ -1802,160 +1999,172 @@ static void push_rt_tasks(struct rq *rq)
 }
 
 #ifdef HAVE_RT_PUSH_IPI
+
 /*
- * The search for the next cpu always starts at rq->cpu and ends
- * when we reach rq->cpu again. It will never return rq->cpu.
- * This returns the next cpu to check, or nr_cpu_ids if the loop
- * is complete.
+ * When a high priority task schedules out from a CPU and a lower priority
+ * task is scheduled in, a check is made to see if there's any RT tasks
+ * on other CPUs that are waiting to run because a higher priority RT task
+ * is currently running on its CPU. In this case, the CPU with multiple RT
+ * tasks queued on it (overloaded) needs to be notified that a CPU has opened
+ * up that may be able to run one of its non-running queued RT tasks.
+ *
+ * All CPUs with overloaded RT tasks need to be notified as there is currently
+ * no way to know which of these CPUs have the highest priority task waiting
+ * to run. Instead of trying to take a spinlock on each of these CPUs,
+ * which has shown to cause large latency when done on machines with many
+ * CPUs, sending an IPI to the CPUs to have them push off the overloaded
+ * RT tasks waiting to run.
+ *
+ * Just sending an IPI to each of the CPUs is also an issue, as on large
+ * count CPU machines, this can cause an IPI storm on a CPU, especially
+ * if its the only CPU with multiple RT tasks queued, and a large number
+ * of CPUs scheduling a lower priority task at the same time.
+ *
+ * Each root domain has its own irq work function that can iterate over
+ * all CPUs with RT overloaded tasks. Since all CPUs with overloaded RT
+ * tassk must be checked if there's one or many CPUs that are lowering
+ * their priority, there's a single irq work iterator that will try to
+ * push off RT tasks that are waiting to run.
+ *
+ * When a CPU schedules a lower priority task, it will kick off the
+ * irq work iterator that will jump to each CPU with overloaded RT tasks.
+ * As it only takes the first CPU that schedules a lower priority task
+ * to start the process, the rto_start variable is incremented and if
+ * the atomic result is one, then that CPU will try to take the rto_lock.
+ * This prevents high contention on the lock as the process handles all
+ * CPUs scheduling lower priority tasks.
+ *
+ * All CPUs that are scheduling a lower priority task will increment the
+ * rt_loop_next variable. This will make sure that the irq work iterator
+ * checks all RT overloaded CPUs whenever a CPU schedules a new lower
+ * priority task, even if the iterator is in the middle of a scan. Incrementing
+ * the rt_loop_next will cause the iterator to perform another scan.
  *
- * rq->rt.push_cpu holds the last cpu returned by this function,
- * or if this is the first instance, it must hold rq->cpu.
  */
-static int rto_next_cpu(struct rq *rq)
+static int rto_next_cpu(struct root_domain *rd)
 {
-	int prev_cpu = rq->rt.push_cpu;
+	int next;
 	int cpu;
 
-	cpu = cpumask_next(prev_cpu, rq->rd->rto_mask);
-
 	/*
-	 * If the previous cpu is less than the rq's CPU, then it already
-	 * passed the end of the mask, and has started from the beginning.
-	 * We end if the next CPU is greater or equal to rq's CPU.
+	 * When starting the IPI RT pushing, the rto_cpu is set to -1,
+	 * rt_next_cpu() will simply return the first CPU found in
+	 * the rto_mask.
+	 *
+	 * If rto_next_cpu() is called with rto_cpu is a valid cpu, it
+	 * will return the next CPU found in the rto_mask.
+	 *
+	 * If there are no more CPUs left in the rto_mask, then a check is made
+	 * against rto_loop and rto_loop_next. rto_loop is only updated with
+	 * the rto_lock held, but any CPU may increment the rto_loop_next
+	 * without any locking.
 	 */
-	if (prev_cpu < rq->cpu) {
-		if (cpu >= rq->cpu)
-			return nr_cpu_ids;
+	for (;;) {
 
-	} else if (cpu >= nr_cpu_ids) {
-		/*
-		 * We passed the end of the mask, start at the beginning.
-		 * If the result is greater or equal to the rq's CPU, then
-		 * the loop is finished.
-		 */
-		cpu = cpumask_first(rq->rd->rto_mask);
-		if (cpu >= rq->cpu)
-			return nr_cpu_ids;
-	}
-	rq->rt.push_cpu = cpu;
+		/* When rto_cpu is -1 this acts like cpumask_first() */
+		cpu = cpumask_next(rd->rto_cpu, rd->rto_mask);
 
-	/* Return cpu to let the caller know if the loop is finished or not */
-	return cpu;
-}
+		rd->rto_cpu = cpu;
 
-static int find_next_push_cpu(struct rq *rq)
-{
-	struct rq *next_rq;
-	int cpu;
+		if (cpu < nr_cpu_ids)
+			return cpu;
 
-	while (1) {
-		cpu = rto_next_cpu(rq);
-		if (cpu >= nr_cpu_ids)
-			break;
-		next_rq = cpu_rq(cpu);
+		rd->rto_cpu = -1;
 
-		/* Make sure the next rq can push to this rq */
-		if (next_rq->rt.highest_prio.next < rq->rt.highest_prio.curr)
+		/*
+		 * ACQUIRE ensures we see the @rto_mask changes
+		 * made prior to the @next value observed.
+		 *
+		 * Matches WMB in rt_set_overload().
+		 */
+		next = atomic_read_acquire(&rd->rto_loop_next);
+
+		if (rd->rto_loop == next)
 			break;
+
+		rd->rto_loop = next;
 	}
 
-	return cpu;
+	return -1;
 }
 
-#define RT_PUSH_IPI_EXECUTING		1
-#define RT_PUSH_IPI_RESTART		2
+static inline bool rto_start_trylock(atomic_t *v)
+{
+	return !atomic_cmpxchg_acquire(v, 0, 1);
+}
 
-static void tell_cpu_to_push(struct rq *rq)
+static inline void rto_start_unlock(atomic_t *v)
 {
-	int cpu;
+	atomic_set_release(v, 0);
+}
 
-	if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
-		raw_spin_lock(&rq->rt.push_lock);
-		/* Make sure it's still executing */
-		if (rq->rt.push_flags & RT_PUSH_IPI_EXECUTING) {
-			/*
-			 * Tell the IPI to restart the loop as things have
-			 * changed since it started.
-			 */
-			rq->rt.push_flags |= RT_PUSH_IPI_RESTART;
-			raw_spin_unlock(&rq->rt.push_lock);
-			return;
-		}
-		raw_spin_unlock(&rq->rt.push_lock);
-	}
+static void tell_cpu_to_push(struct rq *rq)
+{
+	int cpu = -1;
 
-	/* When here, there's no IPI going around */
+	/* Keep the loop going if the IPI is currently active */
+	atomic_inc(&rq->rd->rto_loop_next);
 
-	rq->rt.push_cpu = rq->cpu;
-	cpu = find_next_push_cpu(rq);
-	if (cpu >= nr_cpu_ids)
+	/* Only one CPU can initiate a loop at a time */
+	if (!rto_start_trylock(&rq->rd->rto_loop_start))
 		return;
 
-	rq->rt.push_flags = RT_PUSH_IPI_EXECUTING;
+	raw_spin_lock(&rq->rd->rto_lock);
+
+	/*
+	 * The rto_cpu is updated under the lock, if it has a valid cpu
+	 * then the IPI is still running and will continue due to the
+	 * update to loop_next, and nothing needs to be done here.
+	 * Otherwise it is finishing up and an ipi needs to be sent.
+	 */
+	if (rq->rd->rto_cpu < 0)
+		cpu = rto_next_cpu(rq->rd);
+
+	raw_spin_unlock(&rq->rd->rto_lock);
 
-	irq_work_queue_on(&rq->rt.push_work, cpu);
+	rto_start_unlock(&rq->rd->rto_loop_start);
+
+	if (cpu >= 0) {
+		/* Make sure the rd does not get freed while pushing */
+		sched_get_rd(rq->rd);
+		irq_work_queue_on(&rq->rd->rto_push_work, cpu);
+	}
 }
 
 /* Called from hardirq context */
-static void try_to_push_tasks(void *arg)
+void rto_push_irq_work_func(struct irq_work *work)
 {
-	struct rt_rq *rt_rq = arg;
-	struct rq *rq, *src_rq;
-	int this_cpu;
+	struct root_domain *rd =
+		container_of(work, struct root_domain, rto_push_work);
+	struct rq *rq;
 	int cpu;
 
-	this_cpu = rt_rq->push_cpu;
-
-	/* Paranoid check */
-	BUG_ON(this_cpu != smp_processor_id());
-
-	rq = cpu_rq(this_cpu);
-	src_rq = rq_of_rt_rq(rt_rq);
+	rq = this_rq();
 
-again:
+	/*
+	 * We do not need to grab the lock to check for has_pushable_tasks.
+	 * When it gets updated, a check is made if a push is possible.
+	 */
 	if (has_pushable_tasks(rq)) {
 		raw_spin_lock(&rq->lock);
-		push_rt_task(rq);
+		push_rt_tasks(rq);
 		raw_spin_unlock(&rq->lock);
 	}
 
-	/* Pass the IPI to the next rt overloaded queue */
-	raw_spin_lock(&rt_rq->push_lock);
-	/*
-	 * If the source queue changed since the IPI went out,
-	 * we need to restart the search from that CPU again.
-	 */
-	if (rt_rq->push_flags & RT_PUSH_IPI_RESTART) {
-		rt_rq->push_flags &= ~RT_PUSH_IPI_RESTART;
-		rt_rq->push_cpu = src_rq->cpu;
-	}
+	raw_spin_lock(&rd->rto_lock);
 
-	cpu = find_next_push_cpu(src_rq);
+	/* Pass the IPI to the next rt overloaded queue */
+	cpu = rto_next_cpu(rd);
 
-	if (cpu >= nr_cpu_ids)
-		rt_rq->push_flags &= ~RT_PUSH_IPI_EXECUTING;
-	raw_spin_unlock(&rt_rq->push_lock);
+	raw_spin_unlock(&rd->rto_lock);
 
-	if (cpu >= nr_cpu_ids)
+	if (cpu < 0) {
+		sched_put_rd(rd);
 		return;
-
-	/*
-	 * It is possible that a restart caused this CPU to be
-	 * chosen again. Don't bother with an IPI, just see if we
-	 * have more to push.
-	 */
-	if (unlikely(cpu == rq->cpu))
-		goto again;
+	}
 
 	/* Try the next RT overloaded CPU */
-	irq_work_queue_on(&rt_rq->push_work, cpu);
-}
-
-static void push_irq_work_func(struct irq_work *work)
-{
-	struct rt_rq *rt_rq = container_of(work, struct rt_rq, push_work);
-
-	try_to_push_tasks(rt_rq);
+	irq_work_queue_on(&rd->rto_push_work, cpu);
 }
 #endif /* HAVE_RT_PUSH_IPI */
 
@@ -1965,8 +2174,9 @@ static void pull_rt_task(struct rq *this_rq)
 	bool resched = false;
 	struct task_struct *p;
 	struct rq *src_rq;
+	int rt_overload_count = rt_overloaded(this_rq);
 
-	if (likely(!rt_overloaded(this_rq)))
+	if (likely(!rt_overload_count))
 		return;
 
 	/*
@@ -1975,6 +2185,11 @@ static void pull_rt_task(struct rq *this_rq)
 	 */
 	smp_rmb();
 
+	/* If we are the only overloaded CPU do nothing */
+	if (rt_overload_count == 1 &&
+	    cpumask_test_cpu(this_rq->cpu, this_rq->rd->rto_mask))
+		return;
+
 #ifdef HAVE_RT_PUSH_IPI
 	if (sched_feat(RT_PUSH_IPI)) {
 		tell_cpu_to_push(this_rq);
@@ -2034,7 +2249,9 @@ static void pull_rt_task(struct rq *this_rq)
 			resched = true;
 
 			deactivate_task(src_rq, p, 0);
+			p->on_rq = TASK_ON_RQ_MIGRATING;
 			set_task_cpu(p, this_cpu);
+			p->on_rq = TASK_ON_RQ_QUEUED;
 			activate_task(this_rq, p, 0);
 			/*
 			 * We continue with the search, just in
@@ -2095,6 +2312,13 @@ static void rq_offline_rt(struct rq *rq)
 static void switched_from_rt(struct rq *rq, struct task_struct *p)
 {
 	/*
+	 * On class switch from rt, always cancel active schedtune timers,
+	 * this handles the cases where we switch class for a task that is
+	 * already rt-dequeued but has a running timer.
+	 */
+	schedtune_dequeue_rt(rq, p);
+
+	/*
 	 * If there are other RT tasks then we will reschedule
 	 * and the scheduling of the other RT tasks will handle
 	 * the balancing. But if we are the last RT task
@@ -2136,10 +2360,9 @@ static void switched_to_rt(struct rq *rq, struct task_struct *p)
 #ifdef CONFIG_SMP
 		if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
 			queue_push_tasks(rq);
-#else
-		if (p->prio < rq->curr->prio)
-			resched_curr(rq);
 #endif /* CONFIG_SMP */
+		if (p->prio < rq->curr->prio && cpu_online(cpu_of(rq)))
+			resched_curr(rq);
 	}
 }