---
 kernel/sched/bfs.c |   51 +++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 43 insertions(+), 8 deletions(-)

Index: linux-4.8-bfs/kernel/sched/bfs.c
===================================================================
--- linux-4.8-bfs.orig/kernel/sched/bfs.c	2016-10-07 10:04:25.000000000 +1100
+++ linux-4.8-bfs/kernel/sched/bfs.c	2016-10-09 09:24:09.252592140 +1100
@@ -949,11 +949,19 @@ static void update_load_avg(struct rq *r
 		cpufreq_trigger(grq.niffies, rq->load_avg);
 }
 
+/* Entered with rq locked */
+static inline void resched_if_idle(struct rq *rq)
+{
+	if (rq_idle(rq) && rq->online)
+		resched_task(rq->curr);
+}
+
 /*
  * activate_task - move a task to the runqueue. Enter with grq locked.
  */
 static void activate_task(struct task_struct *p, struct rq *rq)
 {
+	resched_if_idle(rq);
 	update_clocks(rq);
 
 	/*
@@ -1517,24 +1525,39 @@ static void try_to_wake_up_local(struct
 	struct rq *rq = task_rq(p);
 	bool success = false;
 
+	if (WARN_ON_ONCE(rq != this_rq()) ||
+	    WARN_ON_ONCE(p == current))
+		return;
+
 	lockdep_assert_held(&grq.lock);
 
+	if (!raw_spin_trylock(&p->pi_lock)) {
+		/*
+		 * This is OK, because current is on_cpu, which avoids it being
+		 * picked for load-balance and preemption/IRQs are still
+		 * disabled avoiding further scheduler activity on it and we've
+		 * not yet picked a replacement task.
+		 */
+		grq_unlock();
+		raw_spin_lock(&p->pi_lock);
+		grq_lock();
+	}
+
 	if (!(p->state & TASK_NORMAL))
-		return;
+		goto out;
 
 	trace_sched_waking(p);
 
 	if (!task_queued(p)) {
-		if (likely(!task_running(p))) {
-			schedstat_inc(rq, ttwu_count);
-			schedstat_inc(rq, ttwu_local);
-		}
 		ttwu_activate(p, rq, false);
-		if (schedstat_enabled())
-			ttwu_stat(p, smp_processor_id(), 0);
 		success = true;
 	}
+
 	ttwu_post_activation(p, rq, success);
+	if (schedstat_enabled())
+		ttwu_stat(p, smp_processor_id(), 0);
+out:
+	raw_spin_unlock(&p->pi_lock);
 }
 
 /**
@@ -1568,6 +1591,9 @@ static void time_slice_expired(struct ta
  */
 int sched_fork(unsigned long __maybe_unused clone_flags, struct task_struct *p)
 {
+	unsigned long flags;
+	int cpu = get_cpu();
+
 #ifdef CONFIG_PREEMPT_NOTIFIERS
 	INIT_HLIST_HEAD(&p->preempt_notifiers);
 #endif
@@ -1617,12 +1643,21 @@ int sched_fork(unsigned long __maybe_unu
 		p->sched_reset_on_fork = 0;
 	}
 
+	/*
+	 * Silence PROVE_RCU.
+	 */
+	raw_spin_lock_irqsave(&p->pi_lock, flags);
+	set_task_cpu(p, cpu);
+	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+
 #ifdef CONFIG_SCHED_INFO
 	if (unlikely(sched_info_on()))
 		memset(&p->sched_info, 0, sizeof(p->sched_info));
 #endif
 	p->on_cpu = false;
 	init_task_preempt_count(p);
+
+	put_cpu();
 	return 0;
 }
 
@@ -3420,7 +3455,7 @@ static void __sched notrace __schedule(b
 				to_wakeup = wq_worker_sleeping(prev);
 				if (to_wakeup) {
 					/* This shouldn't happen, but does */
-					if (unlikely(to_wakeup == prev))
+					if (WARN_ON(to_wakeup == prev))
 						deactivate = false;
 					else
 						try_to_wake_up_local(to_wakeup);