Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 7110 insertions, 0 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
new file mode 100644
index 000000000..32af895bd
--- /dev/null
+++ b/kernel/sched/core.c
@@ -0,0 +1,7110 @@
+/*
+ *  kernel/sched/core.c
+ *
+ *  Core kernel scheduler code and related syscalls
+ *
+ *  Copyright (C) 1991-2002  Linus Torvalds
+ */
+#include "sched.h"
+
+#include <linux/nospec.h>
+
+#include <linux/kcov.h>
+
+#include <asm/switch_to.h>
+#include <asm/tlb.h>
+
+#include "../workqueue_internal.h"
+#include "../smpboot.h"
+
+#include "pelt.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/sched.h>
+
+DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
+
+#ifdef CONFIG_SCHED_DEBUG
+/*
+ * Debugging: various feature bits
+ *
+ * If SCHED_DEBUG is disabled, each compilation unit has its own copy of
+ * sysctl_sched_features, defined in sched.h, to allow constants propagation
+ * at compile time and compiler optimization based on features default.
+ */
+#define SCHED_FEAT(name, enabled)	\
+	(1UL << __SCHED_FEAT_##name) * enabled |
+const_debug unsigned int sysctl_sched_features =
+#include "features.h"
+	0;
+#undef SCHED_FEAT
+#endif
+
+/*
+ * Number of tasks to iterate in a single balance run.
+ * Limited because this is done with IRQs disabled.
+ */
+const_debug unsigned int sysctl_sched_nr_migrate = 32;
+
+/*
+ * period over which we measure -rt task CPU usage in us.
+ * default: 1s
+ */
+unsigned int sysctl_sched_rt_period = 1000000;
+
+__read_mostly int scheduler_running;
+
+/*
+ * part of the period that we allow rt tasks to run in us.
+ * default: 0.95s
+ */
+int sysctl_sched_rt_runtime = 950000;
+
+/*
+ * __task_rq_lock - lock the rq @p resides on.
+ */
+struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
+	__acquires(rq->lock)
+{
+	struct rq *rq;
+
+	lockdep_assert_held(&p->pi_lock);
+
+	for (;;) {
+		rq = task_rq(p);
+		raw_spin_lock(&rq->lock);
+		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
+			rq_pin_lock(rq, rf);
+			return rq;
+		}
+		raw_spin_unlock(&rq->lock);
+
+		while (unlikely(task_on_rq_migrating(p)))
+			cpu_relax();
+	}
+}
+
+/*
+ * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
+ */
+struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
+	__acquires(p->pi_lock)
+	__acquires(rq->lock)
+{
+	struct rq *rq;
+
+	for (;;) {
+		raw_spin_lock_irqsave(&p->pi_lock, rf->flags);
+		rq = task_rq(p);
+		raw_spin_lock(&rq->lock);
+		/*
+		 *	move_queued_task()		task_rq_lock()
+		 *
+		 *	ACQUIRE (rq->lock)
+		 *	[S] ->on_rq = MIGRATING		[L] rq = task_rq()
+		 *	WMB (__set_task_cpu())		ACQUIRE (rq->lock);
+		 *	[S] ->cpu = new_cpu		[L] task_rq()
+		 *					[L] ->on_rq
+		 *	RELEASE (rq->lock)
+		 *
+		 * If we observe the old CPU in task_rq_lock(), the acquire of
+		 * the old rq->lock will fully serialize against the stores.
+		 *
+		 * If we observe the new CPU in task_rq_lock(), the address
+		 * dependency headed by '[L] rq = task_rq()' and the acquire
+		 * will pair with the WMB to ensure we then also see migrating.
+		 */
+		if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
+			rq_pin_lock(rq, rf);
+			return rq;
+		}
+		raw_spin_unlock(&rq->lock);
+		raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
+
+		while (unlikely(task_on_rq_migrating(p)))
+			cpu_relax();
+	}
+}
+
+/*
+ * RQ-clock updating methods:
+ */
+
+static void update_rq_clock_task(struct rq *rq, s64 delta)
+{
+/*
+ * In theory, the compile should just see 0 here, and optimize out the call
+ * to sched_rt_avg_update. But I don't trust it...
+ */
+	s64 __maybe_unused steal = 0, irq_delta = 0;
+
+#ifdef CONFIG_IRQ_TIME_ACCOUNTING
+	irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
+
+	/*
+	 * Since irq_time is only updated on {soft,}irq_exit, we might run into
+	 * this case when a previous update_rq_clock() happened inside a
+	 * {soft,}irq region.
+	 *
+	 * When this happens, we stop ->clock_task and only update the
+	 * prev_irq_time stamp to account for the part that fit, so that a next
+	 * update will consume the rest. This ensures ->clock_task is
+	 * monotonic.
+	 *
+	 * It does however cause some slight miss-attribution of {soft,}irq
+	 * time, a more accurate solution would be to update the irq_time using
+	 * the current rq->clock timestamp, except that would require using
+	 * atomic ops.
+	 */
+	if (irq_delta > delta)
+		irq_delta = delta;
+
+	rq->prev_irq_time += irq_delta;
+	delta -= irq_delta;
+#endif
+#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
+	if (static_key_false((&paravirt_steal_rq_enabled))) {
+		steal = paravirt_steal_clock(cpu_of(rq));
+		steal -= rq->prev_steal_time_rq;
+
+		if (unlikely(steal > delta))
+			steal = delta;
+
+		rq->prev_steal_time_rq += steal;
+		delta -= steal;
+	}
+#endif
+
+	rq->clock_task += delta;
+
+#ifdef CONFIG_HAVE_SCHED_AVG_IRQ
+	if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
+		update_irq_load_avg(rq, irq_delta + steal);
+#endif
+}
+
+void update_rq_clock(struct rq *rq)
+{
+	s64 delta;
+
+	lockdep_assert_held(&rq->lock);
+
+	if (rq->clock_update_flags & RQCF_ACT_SKIP)
+		return;
+
+#ifdef CONFIG_SCHED_DEBUG
+	if (sched_feat(WARN_DOUBLE_CLOCK))
+		SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED);
+	rq->clock_update_flags |= RQCF_UPDATED;
+#endif
+
+	delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
+	if (delta < 0)
+		return;
+	rq->clock += delta;
+	update_rq_clock_task(rq, delta);
+}
+
+
+#ifdef CONFIG_SCHED_HRTICK
+/*
+ * Use HR-timers to deliver accurate preemption points.
+ */
+
+static void hrtick_clear(struct rq *rq)
+{
+	if (hrtimer_active(&rq->hrtick_timer))
+		hrtimer_cancel(&rq->hrtick_timer);
+}
+
+/*
+ * High-resolution timer tick.
+ * Runs from hardirq context with interrupts disabled.
+ */
+static enum hrtimer_restart hrtick(struct hrtimer *timer)
+{
+	struct rq *rq = container_of(timer, struct rq, hrtick_timer);
+	struct rq_flags rf;
+
+	WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
+
+	rq_lock(rq, &rf);
+	update_rq_clock(rq);
+	rq->curr->sched_class->task_tick(rq, rq->curr, 1);
+	rq_unlock(rq, &rf);
+
+	return HRTIMER_NORESTART;
+}
+
+#ifdef CONFIG_SMP
+
+static void __hrtick_restart(struct rq *rq)
+{
+	struct hrtimer *timer = &rq->hrtick_timer;
+
+	hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
+}
+
+/*
+ * called from hardirq (IPI) context
+ */
+static void __hrtick_start(void *arg)
+{
+	struct rq *rq = arg;
+	struct rq_flags rf;
+
+	rq_lock(rq, &rf);
+	__hrtick_restart(rq);
+	rq->hrtick_csd_pending = 0;
+	rq_unlock(rq, &rf);
+}
+
+/*
+ * Called to set the hrtick timer state.
+ *
+ * called with rq->lock held and irqs disabled
+ */
+void hrtick_start(struct rq *rq, u64 delay)
+{
+	struct hrtimer *timer = &rq->hrtick_timer;
+	ktime_t time;
+	s64 delta;
+
+	/*
+	 * Don't schedule slices shorter than 10000ns, that just
+	 * doesn't make sense and can cause timer DoS.
+	 */
+	delta = max_t(s64, delay, 10000LL);
+	time = ktime_add_ns(timer->base->get_time(), delta);
+
+	hrtimer_set_expires(timer, time);
+
+	if (rq == this_rq()) {
+		__hrtick_restart(rq);
+	} else if (!rq->hrtick_csd_pending) {
+		smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
+		rq->hrtick_csd_pending = 1;
+	}
+}
+
+#else
+/*
+ * Called to set the hrtick timer state.
+ *
+ * called with rq->lock held and irqs disabled
+ */
+void hrtick_start(struct rq *rq, u64 delay)
+{
+	/*
+	 * Don't schedule slices shorter than 10000ns, that just
+	 * doesn't make sense. Rely on vruntime for fairness.
+	 */
+	delay = max_t(u64, delay, 10000LL);
+	hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
+		      HRTIMER_MODE_REL_PINNED);
+}
+#endif /* CONFIG_SMP */
+
+static void hrtick_rq_init(struct rq *rq)
+{
+#ifdef CONFIG_SMP
+	rq->hrtick_csd_pending = 0;
+
+	rq->hrtick_csd.flags = 0;
+	rq->hrtick_csd.func = __hrtick_start;
+	rq->hrtick_csd.info = rq;
+#endif
+
+	hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	rq->hrtick_timer.function = hrtick;
+}
+#else	/* CONFIG_SCHED_HRTICK */
+static inline void hrtick_clear(struct rq *rq)
+{
+}
+
+static inline void hrtick_rq_init(struct rq *rq)
+{
+}
+#endif	/* CONFIG_SCHED_HRTICK */
+
+/*
+ * cmpxchg based fetch_or, macro so it works for different integer types
+ */
+#define fetch_or(ptr, mask)						\
+	({								\
+		typeof(ptr) _ptr = (ptr);				\
+		typeof(mask) _mask = (mask);				\
+		typeof(*_ptr) _old, _val = *_ptr;			\
+									\
+		for (;;) {						\
+			_old = cmpxchg(_ptr, _val, _val | _mask);	\
+			if (_old == _val)				\
+				break;					\
+			_val = _old;					\
+		}							\
+	_old;								\
+})
+
+#if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
+/*
+ * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
+ * this avoids any races wrt polling state changes and thereby avoids
+ * spurious IPIs.
+ */
+static bool set_nr_and_not_polling(struct task_struct *p)
+{
+	struct thread_info *ti = task_thread_info(p);
+	return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
+}
+
+/*
+ * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
+ *
+ * If this returns true, then the idle task promises to call
+ * sched_ttwu_pending() and reschedule soon.
+ */
+static bool set_nr_if_polling(struct task_struct *p)
+{
+	struct thread_info *ti = task_thread_info(p);
+	typeof(ti->flags) old, val = READ_ONCE(ti->flags);
+
+	for (;;) {
+		if (!(val & _TIF_POLLING_NRFLAG))
+			return false;
+		if (val & _TIF_NEED_RESCHED)
+			return true;
+		old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
+		if (old == val)
+			break;
+		val = old;
+	}
+	return true;
+}
+
+#else
+static bool set_nr_and_not_polling(struct task_struct *p)
+{
+	set_tsk_need_resched(p);
+	return true;
+}
+
+#ifdef CONFIG_SMP
+static bool set_nr_if_polling(struct task_struct *p)
+{
+	return false;
+}
+#endif
+#endif
+
+void wake_q_add(struct wake_q_head *head, struct task_struct *task)
+{
+	struct wake_q_node *node = &task->wake_q;
+
+	/*
+	 * Atomically grab the task, if ->wake_q is !nil already it means
+	 * its already queued (either by us or someone else) and will get the
+	 * wakeup due to that.
+	 *
+	 * In order to ensure that a pending wakeup will observe our pending
+	 * state, even in the failed case, an explicit smp_mb() must be used.
+	 */
+	smp_mb__before_atomic();
+	if (cmpxchg_relaxed(&node->next, NULL, WAKE_Q_TAIL))
+		return;
+
+	get_task_struct(task);
+
+	/*
+	 * The head is context local, there can be no concurrency.
+	 */
+	*head->lastp = node;
+	head->lastp = &node->next;
+}
+
+void wake_up_q(struct wake_q_head *head)
+{
+	struct wake_q_node *node = head->first;
+
+	while (node != WAKE_Q_TAIL) {
+		struct task_struct *task;
+
+		task = container_of(node, struct task_struct, wake_q);
+		BUG_ON(!task);
+		/* Task can safely be re-inserted now: */
+		node = node->next;
+		task->wake_q.next = NULL;
+
+		/*
+		 * wake_up_process() executes a full barrier, which pairs with
+		 * the queueing in wake_q_add() so as not to miss wakeups.
+		 */
+		wake_up_process(task);
+		put_task_struct(task);
+	}
+}
+
+/*
+ * 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_curr(struct rq *rq)
+{
+	struct task_struct *curr = rq->curr;
+	int cpu;
+
+	lockdep_assert_held(&rq->lock);
+
+	if (test_tsk_need_resched(curr))
+		return;
+
+	cpu = cpu_of(rq);
+
+	if (cpu == smp_processor_id()) {
+		set_tsk_need_resched(curr);
+		set_preempt_need_resched();
+		return;
+	}
+
+	if (set_nr_and_not_polling(curr))
+		smp_send_reschedule(cpu);
+	else
+		trace_sched_wake_idle_without_ipi(cpu);
+}
+
+void resched_cpu(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&rq->lock, flags);
+	if (cpu_online(cpu) || cpu == smp_processor_id())
+		resched_curr(rq);
+	raw_spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+#ifdef CONFIG_SMP
+#ifdef CONFIG_NO_HZ_COMMON
+/*
+ * In the semi idle case, use the nearest busy CPU for migrating timers
+ * from an idle CPU.  This is good for power-savings.
+ *
+ * We don't do similar optimization for completely idle system, as
+ * selecting an idle CPU will add more delays to the timers than intended
+ * (as that CPU's timer base may not be uptodate wrt jiffies etc).
+ */
+int get_nohz_timer_target(void)
+{
+	int i, cpu = smp_processor_id();
+	struct sched_domain *sd;
+
+	if (!idle_cpu(cpu) && housekeeping_cpu(cpu, HK_FLAG_TIMER))
+		return cpu;
+
+	rcu_read_lock();
+	for_each_domain(cpu, sd) {
+		for_each_cpu(i, sched_domain_span(sd)) {
+			if (cpu == i)
+				continue;
+
+			if (!idle_cpu(i) && housekeeping_cpu(i, HK_FLAG_TIMER)) {
+				cpu = i;
+				goto unlock;
+			}
+		}
+	}
+
+	if (!housekeeping_cpu(cpu, HK_FLAG_TIMER))
+		cpu = housekeeping_any_cpu(HK_FLAG_TIMER);
+unlock:
+	rcu_read_unlock();
+	return cpu;
+}
+
+/*
+ * When add_timer_on() enqueues a timer into the timer wheel of an
+ * idle CPU then this timer might expire before the next timer event
+ * which is scheduled to wake up that CPU. In case of a completely
+ * idle system the next event might even be infinite time into the
+ * future. wake_up_idle_cpu() ensures that the CPU is woken up and
+ * leaves the inner idle loop so the newly added timer is taken into
+ * account when the CPU goes back to idle and evaluates the timer
+ * wheel for the next timer event.
+ */
+static void wake_up_idle_cpu(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+
+	if (cpu == smp_processor_id())
+		return;
+
+	if (set_nr_and_not_polling(rq->idle))
+		smp_send_reschedule(cpu);
+	else
+		trace_sched_wake_idle_without_ipi(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 (cpu_is_offline(cpu))
+		return true;  /* Don't try to wake offline CPUs. */
+	if (tick_nohz_full_cpu(cpu)) {
+		if (cpu != smp_processor_id() ||
+		    tick_nohz_tick_stopped())
+			tick_nohz_full_kick_cpu(cpu);
+		return true;
+	}
+
+	return false;
+}
+
+/*
+ * Wake up the specified CPU.  If the CPU is going offline, it is the
+ * caller's responsibility to deal with the lost wakeup, for example,
+ * by hooking into the CPU_DEAD notifier like timers and hrtimers do.
+ */
+void wake_up_nohz_cpu(int cpu)
+{
+	if (!wake_up_full_nohz_cpu(cpu))
+		wake_up_idle_cpu(cpu);
+}
+
+static inline bool got_nohz_idle_kick(void)
+{
+	int cpu = smp_processor_id();
+
+	if (!(atomic_read(nohz_flags(cpu)) & NOHZ_KICK_MASK))
+		return false;
+
+	if (idle_cpu(cpu) && !need_resched())
+		return true;
+
+	/*
+	 * We can't run Idle Load Balance on this CPU for this time so we
+	 * cancel it and clear NOHZ_BALANCE_KICK
+	 */
+	atomic_andnot(NOHZ_KICK_MASK, nohz_flags(cpu));
+	return false;
+}
+
+#else /* CONFIG_NO_HZ_COMMON */
+
+static inline bool got_nohz_idle_kick(void)
+{
+	return false;
+}
+
+#endif /* CONFIG_NO_HZ_COMMON */
+
+#ifdef CONFIG_NO_HZ_FULL
+bool sched_can_stop_tick(struct rq *rq)
+{
+	int fifo_nr_running;
+
+	/* Deadline tasks, even if single, need the tick */
+	if (rq->dl.dl_nr_running)
+		return false;
+
+	/*
+	 * If there are more than one RR tasks, we need the tick to effect the
+	 * actual RR behaviour.
+	 */
+	if (rq->rt.rr_nr_running) {
+		if (rq->rt.rr_nr_running == 1)
+			return true;
+		else
+			return false;
+	}
+
+	/*
+	 * If there's no RR tasks, but FIFO tasks, we can skip the tick, no
+	 * forced preemption between FIFO tasks.
+	 */
+	fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
+	if (fifo_nr_running)
+		return true;
+
+	/*
+	 * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left;
+	 * if there's more than one we need the tick for involuntary
+	 * preemption.
+	 */
+	if (rq->nr_running > 1)
+		return false;
+
+	return true;
+}
+#endif /* CONFIG_NO_HZ_FULL */
+#endif /* CONFIG_SMP */
+
+#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
+			(defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
+/*
+ * Iterate task_group tree rooted at *from, calling @down when first entering a
+ * node and @up when leaving it for the final time.
+ *
+ * Caller must hold rcu_lock or sufficient equivalent.
+ */
+int walk_tg_tree_from(struct task_group *from,
+			     tg_visitor down, tg_visitor up, void *data)
+{
+	struct task_group *parent, *child;
+	int ret;
+
+	parent = from;
+
+down:
+	ret = (*down)(parent, data);
+	if (ret)
+		goto out;
+	list_for_each_entry_rcu(child, &parent->children, siblings) {
+		parent = child;
+		goto down;
+
+up:
+		continue;
+	}
+	ret = (*up)(parent, data);
+	if (ret || parent == from)
+		goto out;
+
+	child = parent;
+	parent = parent->parent;
+	if (parent)
+		goto up;
+out:
+	return ret;
+}
+
+int tg_nop(struct task_group *tg, void *data)
+{
+	return 0;
+}
+#endif
+
+static void set_load_weight(struct task_struct *p, bool update_load)
+{
+	int prio = p->static_prio - MAX_RT_PRIO;
+	struct load_weight *load = &p->se.load;
+
+	/*
+	 * SCHED_IDLE tasks get minimal weight:
+	 */
+	if (idle_policy(p->policy)) {
+		load->weight = scale_load(WEIGHT_IDLEPRIO);
+		load->inv_weight = WMULT_IDLEPRIO;
+		return;
+	}
+
+	/*
+	 * SCHED_OTHER tasks have to update their load when changing their
+	 * weight
+	 */
+	if (update_load && p->sched_class == &fair_sched_class) {
+		reweight_task(p, prio);
+	} else {
+		load->weight = scale_load(sched_prio_to_weight[prio]);
+		load->inv_weight = sched_prio_to_wmult[prio];
+	}
+}
+
+static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
+{
+	if (!(flags & ENQUEUE_NOCLOCK))
+		update_rq_clock(rq);
+
+	if (!(flags & ENQUEUE_RESTORE))
+		sched_info_queued(rq, p);
+
+	p->sched_class->enqueue_task(rq, p, flags);
+}
+
+static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
+{
+	if (!(flags & DEQUEUE_NOCLOCK))
+		update_rq_clock(rq);
+
+	if (!(flags & DEQUEUE_SAVE))
+		sched_info_dequeued(rq, p);
+
+	p->sched_class->dequeue_task(rq, p, flags);
+}
+
+void activate_task(struct rq *rq, struct task_struct *p, int flags)
+{
+	if (task_contributes_to_load(p))
+		rq->nr_uninterruptible--;
+
+	enqueue_task(rq, p, flags);
+}
+
+void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
+{
+	if (task_contributes_to_load(p))
+		rq->nr_uninterruptible++;
+
+	dequeue_task(rq, p, flags);
+}
+
+/*
+ * __normal_prio - return the priority that is based on the static prio
+ */
+static inline int __normal_prio(struct task_struct *p)
+{
+	return p->static_prio;
+}
+
+/*
+ * Calculate the expected normal priority: i.e. priority
+ * without taking RT-inheritance into account. Might be
+ * boosted by interactivity modifiers. Changes upon fork,
+ * setprio syscalls, and whenever the interactivity
+ * estimator recalculates.
+ */
+static inline int normal_prio(struct task_struct *p)
+{
+	int prio;
+
+	if (task_has_dl_policy(p))
+		prio = MAX_DL_PRIO-1;
+	else if (task_has_rt_policy(p))
+		prio = MAX_RT_PRIO-1 - p->rt_priority;
+	else
+		prio = __normal_prio(p);
+	return prio;
+}
+
+/*
+ * Calculate the current priority, i.e. the priority
+ * taken into account by the scheduler. This value might
+ * be boosted by RT tasks, or might be boosted by
+ * interactivity modifiers. Will be RT if the task got
+ * RT-boosted. If not then it returns p->normal_prio.
+ */
+static int effective_prio(struct task_struct *p)
+{
+	p->normal_prio = normal_prio(p);
+	/*
+	 * If we are RT tasks or we were boosted to RT priority,
+	 * keep the priority unchanged. Otherwise, update priority
+	 * to the normal priority:
+	 */
+	if (!rt_prio(p->prio))
+		return p->normal_prio;
+	return p->prio;
+}
+
+/**
+ * task_curr - is this task currently executing on a CPU?
+ * @p: the task in question.
+ *
+ * Return: 1 if the task is currently executing. 0 otherwise.
+ */
+inline int task_curr(const struct task_struct *p)
+{
+	return cpu_curr(task_cpu(p)) == p;
+}
+
+/*
+ * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
+ * use the balance_callback list if you want balancing.
+ *
+ * this means any call to check_class_changed() must be followed by a call to
+ * balance_callback().
+ */
+static inline void check_class_changed(struct rq *rq, struct task_struct *p,
+				       const struct sched_class *prev_class,
+				       int oldprio)
+{
+	if (prev_class != p->sched_class) {
+		if (prev_class->switched_from)
+			prev_class->switched_from(rq, p);
+
+		p->sched_class->switched_to(rq, p);
+	} else if (oldprio != p->prio || dl_task(p))
+		p->sched_class->prio_changed(rq, p, oldprio);
+}
+
+void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
+{
+	const struct sched_class *class;
+
+	if (p->sched_class == rq->curr->sched_class) {
+		rq->curr->sched_class->check_preempt_curr(rq, p, flags);
+	} else {
+		for_each_class(class) {
+			if (class == rq->curr->sched_class)
+				break;
+			if (class == p->sched_class) {
+				resched_curr(rq);
+				break;
+			}
+		}
+	}
+
+	/*
+	 * A queue event has occurred, and we're going to schedule.  In
+	 * this case, we can save a useless back to back clock update.
+	 */
+	if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
+		rq_clock_skip_update(rq);
+}
+
+#ifdef CONFIG_SMP
+
+static inline bool is_per_cpu_kthread(struct task_struct *p)
+{
+	if (!(p->flags & PF_KTHREAD))
+		return false;
+
+	if (p->nr_cpus_allowed != 1)
+		return false;
+
+	return true;
+}
+
+/*
+ * Per-CPU kthreads are allowed to run on !actie && online CPUs, see
+ * __set_cpus_allowed_ptr() and select_fallback_rq().
+ */
+static inline bool is_cpu_allowed(struct task_struct *p, int cpu)
+{
+	if (!cpumask_test_cpu(cpu, &p->cpus_allowed))
+		return false;
+
+	if (is_per_cpu_kthread(p))
+		return cpu_online(cpu);
+
+	return cpu_active(cpu);
+}
+
+/*
+ * This is how migration works:
+ *
+ * 1) we invoke migration_cpu_stop() on the target CPU using
+ *    stop_one_cpu().
+ * 2) stopper starts to run (implicitly forcing the migrated thread
+ *    off the CPU)
+ * 3) it checks whether the migrated task is still in the wrong runqueue.
+ * 4) if it's in the wrong runqueue then the migration thread removes
+ *    it and puts it into the right queue.
+ * 5) stopper completes and stop_one_cpu() returns and the migration
+ *    is done.
+ */
+
+/*
+ * move_queued_task - move a queued task to new rq.
+ *
+ * Returns (locked) new rq. Old rq's lock is released.
+ */
+static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf,
+				   struct task_struct *p, int new_cpu)
+{
+	lockdep_assert_held(&rq->lock);
+
+	WRITE_ONCE(p->on_rq, TASK_ON_RQ_MIGRATING);
+	dequeue_task(rq, p, DEQUEUE_NOCLOCK);
+	set_task_cpu(p, new_cpu);
+	rq_unlock(rq, rf);
+
+	rq = cpu_rq(new_cpu);
+
+	rq_lock(rq, rf);
+	BUG_ON(task_cpu(p) != new_cpu);
+	enqueue_task(rq, p, 0);
+	p->on_rq = TASK_ON_RQ_QUEUED;
+	check_preempt_curr(rq, p, 0);
+
+	return rq;
+}
+
+struct migration_arg {
+	struct task_struct *task;
+	int dest_cpu;
+};
+
+/*
+ * Move (not current) task off this CPU, onto the destination CPU. We're doing
+ * this because either it can't run here any more (set_cpus_allowed()
+ * away from this CPU, or CPU going down), or because we're
+ * attempting to rebalance this task on exec (sched_exec).
+ *
+ * So we race with normal scheduler movements, but that's OK, as long
+ * as the task is no longer on this CPU.
+ */
+static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,
+				 struct task_struct *p, int dest_cpu)
+{
+	/* Affinity changed (again). */
+	if (!is_cpu_allowed(p, dest_cpu))
+		return rq;
+
+	update_rq_clock(rq);
+	rq = move_queued_task(rq, rf, p, dest_cpu);
+
+	return rq;
+}
+
+/*
+ * migration_cpu_stop - this will be executed by a highprio stopper thread
+ * and performs thread migration by bumping thread off CPU then
+ * 'pushing' onto another runqueue.
+ */
+static int migration_cpu_stop(void *data)
+{
+	struct migration_arg *arg = data;
+	struct task_struct *p = arg->task;
+	struct rq *rq = this_rq();
+	struct rq_flags rf;
+
+	/*
+	 * The original target CPU might have gone down and we might
+	 * be on another CPU but it doesn't matter.
+	 */
+	local_irq_disable();
+	/*
+	 * We need to explicitly wake pending tasks before running
+	 * __migrate_task() such that we will not miss enforcing cpus_allowed
+	 * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
+	 */
+	sched_ttwu_pending();
+
+	raw_spin_lock(&p->pi_lock);
+	rq_lock(rq, &rf);
+	/*
+	 * If task_rq(p) != rq, it cannot be migrated here, because we're
+	 * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
+	 * we're holding p->pi_lock.
+	 */
+	if (task_rq(p) == rq) {
+		if (task_on_rq_queued(p))
+			rq = __migrate_task(rq, &rf, p, arg->dest_cpu);
+		else
+			p->wake_cpu = arg->dest_cpu;
+	}
+	rq_unlock(rq, &rf);
+	raw_spin_unlock(&p->pi_lock);
+
+	local_irq_enable();
+	return 0;
+}
+
+/*
+ * sched_class::set_cpus_allowed must do the below, but is not required to
+ * actually call this function.
+ */
+void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask)
+{
+	cpumask_copy(&p->cpus_allowed, new_mask);
+	p->nr_cpus_allowed = cpumask_weight(new_mask);
+}
+
+void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
+{
+	struct rq *rq = task_rq(p);
+	bool queued, running;
+
+	lockdep_assert_held(&p->pi_lock);
+
+	queued = task_on_rq_queued(p);
+	running = task_current(rq, p);
+
+	if (queued) {
+		/*
+		 * Because __kthread_bind() calls this on blocked tasks without
+		 * holding rq->lock.
+		 */
+		lockdep_assert_held(&rq->lock);
+		dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
+	}
+	if (running)
+		put_prev_task(rq, p);
+
+	p->sched_class->set_cpus_allowed(p, new_mask);
+
+	if (queued)
+		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
+	if (running)
+		set_curr_task(rq, p);
+}
+
+/*
+ * Change a given task's CPU affinity. Migrate the thread to a
+ * proper CPU and schedule it away if the CPU it's executing on
+ * is removed from the allowed bitmask.
+ *
+ * NOTE: the caller must have a valid reference to the task, the
+ * task must not exit() & deallocate itself prematurely. The
+ * call is not atomic; no spinlocks may be held.
+ */
+static int __set_cpus_allowed_ptr(struct task_struct *p,
+				  const struct cpumask *new_mask, bool check)
+{
+	const struct cpumask *cpu_valid_mask = cpu_active_mask;
+	unsigned int dest_cpu;
+	struct rq_flags rf;
+	struct rq *rq;
+	int ret = 0;
+
+	rq = task_rq_lock(p, &rf);
+	update_rq_clock(rq);
+
+	if (p->flags & PF_KTHREAD) {
+		/*
+		 * Kernel threads are allowed on online && !active CPUs
+		 */
+		cpu_valid_mask = cpu_online_mask;
+	}
+
+	/*
+	 * Must re-check here, to close a race against __kthread_bind(),
+	 * sched_setaffinity() is not guaranteed to observe the flag.
+	 */
+	if (check && (p->flags & PF_NO_SETAFFINITY)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (cpumask_equal(&p->cpus_allowed, new_mask))
+		goto out;
+
+	dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask);
+	if (dest_cpu >= nr_cpu_ids) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	do_set_cpus_allowed(p, new_mask);
+
+	if (p->flags & PF_KTHREAD) {
+		/*
+		 * For kernel threads that do indeed end up on online &&
+		 * !active we want to ensure they are strict per-CPU threads.
+		 */
+		WARN_ON(cpumask_intersects(new_mask, cpu_online_mask) &&
+			!cpumask_intersects(new_mask, cpu_active_mask) &&
+			p->nr_cpus_allowed != 1);
+	}
+
+	/* Can the task run on the task's current CPU? If so, we're done */
+	if (cpumask_test_cpu(task_cpu(p), new_mask))
+		goto out;
+
+	if (task_running(rq, p) || p->state == TASK_WAKING) {
+		struct migration_arg arg = { p, dest_cpu };
+		/* Need help from migration thread: drop lock and wait. */
+		task_rq_unlock(rq, p, &rf);
+		stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
+		tlb_migrate_finish(p->mm);
+		return 0;
+	} else if (task_on_rq_queued(p)) {
+		/*
+		 * OK, since we're going to drop the lock immediately
+		 * afterwards anyway.
+		 */
+		rq = move_queued_task(rq, &rf, p, dest_cpu);
+	}
+out:
+	task_rq_unlock(rq, p, &rf);
+
+	return ret;
+}
+
+int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
+{
+	return __set_cpus_allowed_ptr(p, new_mask, false);
+}
+EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
+
+void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
+{
+#ifdef CONFIG_SCHED_DEBUG
+	/*
+	 * We should never call set_task_cpu() on a blocked task,
+	 * ttwu() will sort out the placement.
+	 */
+	WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
+			!p->on_rq);
+
+	/*
+	 * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
+	 * because schedstat_wait_{start,end} rebase migrating task's wait_start
+	 * time relying on p->on_rq.
+	 */
+	WARN_ON_ONCE(p->state == TASK_RUNNING &&
+		     p->sched_class == &fair_sched_class &&
+		     (p->on_rq && !task_on_rq_migrating(p)));
+
+#ifdef CONFIG_LOCKDEP
+	/*
+	 * The caller should hold either p->pi_lock or rq->lock, when changing
+	 * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
+	 *
+	 * sched_move_task() holds both and thus holding either pins the cgroup,
+	 * see task_group().
+	 *
+	 * Furthermore, all task_rq users should acquire both locks, see
+	 * task_rq_lock().
+	 */
+	WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
+				      lockdep_is_held(&task_rq(p)->lock)));
+#endif
+	/*
+	 * Clearly, migrating tasks to offline CPUs is a fairly daft thing.
+	 */
+	WARN_ON_ONCE(!cpu_online(new_cpu));
+#endif
+
+	trace_sched_migrate_task(p, new_cpu);
+
+	if (task_cpu(p) != new_cpu) {
+		if (p->sched_class->migrate_task_rq)
+			p->sched_class->migrate_task_rq(p, new_cpu);
+		p->se.nr_migrations++;
+		rseq_migrate(p);
+		perf_event_task_migrate(p);
+	}
+
+	__set_task_cpu(p, new_cpu);
+}
+
+#ifdef CONFIG_NUMA_BALANCING
+static void __migrate_swap_task(struct task_struct *p, int cpu)
+{
+	if (task_on_rq_queued(p)) {
+		struct rq *src_rq, *dst_rq;
+		struct rq_flags srf, drf;
+
+		src_rq = task_rq(p);
+		dst_rq = cpu_rq(cpu);
+
+		rq_pin_lock(src_rq, &srf);
+		rq_pin_lock(dst_rq, &drf);
+
+		p->on_rq = TASK_ON_RQ_MIGRATING;
+		deactivate_task(src_rq, p, 0);
+		set_task_cpu(p, cpu);
+		activate_task(dst_rq, p, 0);
+		p->on_rq = TASK_ON_RQ_QUEUED;
+		check_preempt_curr(dst_rq, p, 0);
+
+		rq_unpin_lock(dst_rq, &drf);
+		rq_unpin_lock(src_rq, &srf);
+
+	} else {
+		/*
+		 * Task isn't running anymore; make it appear like we migrated
+		 * it before it went to sleep. This means on wakeup we make the
+		 * previous CPU our target instead of where it really is.
+		 */
+		p->wake_cpu = cpu;
+	}
+}
+
+struct migration_swap_arg {
+	struct task_struct *src_task, *dst_task;
+	int src_cpu, dst_cpu;
+};
+
+static int migrate_swap_stop(void *data)
+{
+	struct migration_swap_arg *arg = data;
+	struct rq *src_rq, *dst_rq;
+	int ret = -EAGAIN;
+
+	if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
+		return -EAGAIN;
+
+	src_rq = cpu_rq(arg->src_cpu);
+	dst_rq = cpu_rq(arg->dst_cpu);
+
+	double_raw_lock(&arg->src_task->pi_lock,
+			&arg->dst_task->pi_lock);
+	double_rq_lock(src_rq, dst_rq);
+
+	if (task_cpu(arg->dst_task) != arg->dst_cpu)
+		goto unlock;
+
+	if (task_cpu(arg->src_task) != arg->src_cpu)
+		goto unlock;
+
+	if (!cpumask_test_cpu(arg->dst_cpu, &arg->src_task->cpus_allowed))
+		goto unlock;
+
+	if (!cpumask_test_cpu(arg->src_cpu, &arg->dst_task->cpus_allowed))
+		goto unlock;
+
+	__migrate_swap_task(arg->src_task, arg->dst_cpu);
+	__migrate_swap_task(arg->dst_task, arg->src_cpu);
+
+	ret = 0;
+
+unlock:
+	double_rq_unlock(src_rq, dst_rq);
+	raw_spin_unlock(&arg->dst_task->pi_lock);
+	raw_spin_unlock(&arg->src_task->pi_lock);
+
+	return ret;
+}
+
+/*
+ * Cross migrate two tasks
+ */
+int migrate_swap(struct task_struct *cur, struct task_struct *p,
+		int target_cpu, int curr_cpu)
+{
+	struct migration_swap_arg arg;
+	int ret = -EINVAL;
+
+	arg = (struct migration_swap_arg){
+		.src_task = cur,
+		.src_cpu = curr_cpu,
+		.dst_task = p,
+		.dst_cpu = target_cpu,
+	};
+
+	if (arg.src_cpu == arg.dst_cpu)
+		goto out;
+
+	/*
+	 * These three tests are all lockless; this is OK since all of them
+	 * will be re-checked with proper locks held further down the line.
+	 */
+	if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
+		goto out;
+
+	if (!cpumask_test_cpu(arg.dst_cpu, &arg.src_task->cpus_allowed))
+		goto out;
+
+	if (!cpumask_test_cpu(arg.src_cpu, &arg.dst_task->cpus_allowed))
+		goto out;
+
+	trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
+	ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
+
+out:
+	return ret;
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
+/*
+ * wait_task_inactive - wait for a thread to unschedule.
+ *
+ * If @match_state is nonzero, it's the @p->state value just checked and
+ * not expected to change.  If it changes, i.e. @p might have woken up,
+ * then return zero.  When we succeed in waiting for @p to be off its CPU,
+ * we return a positive number (its total switch count).  If a second call
+ * a short while later returns the same number, the caller can be sure that
+ * @p has remained unscheduled the whole time.
+ *
+ * The caller must ensure that the task *will* unschedule sometime soon,
+ * else this function might spin for a *long* time. This function can't
+ * be called with interrupts off, or it may introduce deadlock with
+ * smp_call_function() if an IPI is sent by the same process we are
+ * waiting to become inactive.
+ */
+unsigned long wait_task_inactive(struct task_struct *p, long match_state)
+{
+	int running, queued;
+	struct rq_flags rf;
+	unsigned long ncsw;
+	struct rq *rq;
+
+	for (;;) {
+		/*
+		 * We do the initial early heuristics without holding
+		 * any task-queue locks at all. We'll only try to get
+		 * the runqueue lock when things look like they will
+		 * work out!
+		 */
+		rq = task_rq(p);
+
+		/*
+		 * If the task is actively running on another CPU
+		 * still, just relax and busy-wait without holding
+		 * any locks.
+		 *
+		 * NOTE! Since we don't hold any locks, it's not
+		 * even sure that "rq" stays as the right runqueue!
+		 * But we don't care, since "task_running()" will
+		 * return false if the runqueue has changed and p
+		 * is actually now running somewhere else!
+		 */
+		while (task_running(rq, p)) {
+			if (match_state && unlikely(p->state != match_state))
+				return 0;
+			cpu_relax();
+		}
+
+		/*
+		 * Ok, time to look more closely! We need the rq
+		 * lock now, to be *sure*. If we're wrong, we'll
+		 * just go back and repeat.
+		 */
+		rq = task_rq_lock(p, &rf);
+		trace_sched_wait_task(p);
+		running = task_running(rq, p);
+		queued = task_on_rq_queued(p);
+		ncsw = 0;
+		if (!match_state || p->state == match_state)
+			ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
+		task_rq_unlock(rq, p, &rf);
+
+		/*
+		 * If it changed from the expected state, bail out now.
+		 */
+		if (unlikely(!ncsw))
+			break;
+
+		/*
+		 * Was it really running after all now that we
+		 * checked with the proper locks actually held?
+		 *
+		 * Oops. Go back and try again..
+		 */
+		if (unlikely(running)) {
+			cpu_relax();
+			continue;
+		}
+
+		/*
+		 * It's not enough that it's not actively running,
+		 * it must be off the runqueue _entirely_, and not
+		 * preempted!
+		 *
+		 * So if it was still runnable (but just not actively
+		 * running right now), it's preempted, and we should
+		 * yield - it could be a while.
+		 */
+		if (unlikely(queued)) {
+			ktime_t to = NSEC_PER_SEC / HZ;
+
+			set_current_state(TASK_UNINTERRUPTIBLE);
+			schedule_hrtimeout(&to, HRTIMER_MODE_REL);
+			continue;
+		}
+
+		/*
+		 * Ahh, all good. It wasn't running, and it wasn't
+		 * runnable, which means that it will never become
+		 * running in the future either. We're all done!
+		 */
+		break;
+	}
+
+	return ncsw;
+}
+
+/***
+ * kick_process - kick a running thread to enter/exit the kernel
+ * @p: the to-be-kicked thread
+ *
+ * Cause a process which is running on another CPU to enter
+ * kernel-mode, without any delay. (to get signals handled.)
+ *
+ * NOTE: this function doesn't have to take the runqueue lock,
+ * because all it wants to ensure is that the remote task enters
+ * the kernel. If the IPI races and the task has been migrated
+ * to another CPU then no harm is done and the purpose has been
+ * achieved as well.
+ */
+void kick_process(struct task_struct *p)
+{
+	int cpu;
+
+	preempt_disable();
+	cpu = task_cpu(p);
+	if ((cpu != smp_processor_id()) && task_curr(p))
+		smp_send_reschedule(cpu);
+	preempt_enable();
+}
+EXPORT_SYMBOL_GPL(kick_process);
+
+/*
+ * ->cpus_allowed is protected by both rq->lock and p->pi_lock
+ *
+ * A few notes on cpu_active vs cpu_online:
+ *
+ *  - cpu_active must be a subset of cpu_online
+ *
+ *  - on CPU-up we allow per-CPU kthreads on the online && !active CPU,
+ *    see __set_cpus_allowed_ptr(). At this point the newly online
+ *    CPU isn't yet part of the sched domains, and balancing will not
+ *    see it.
+ *
+ *  - on CPU-down we clear cpu_active() to mask the sched domains and
+ *    avoid the load balancer to place new tasks on the to be removed
+ *    CPU. Existing tasks will remain running there and will be taken
+ *    off.
+ *
+ * This means that fallback selection must not select !active CPUs.
+ * And can assume that any active CPU must be online. Conversely
+ * select_task_rq() below may allow selection of !active CPUs in order
+ * to satisfy the above rules.
+ */
+static int select_fallback_rq(int cpu, struct task_struct *p)
+{
+	int nid = cpu_to_node(cpu);
+	const struct cpumask *nodemask = NULL;
+	enum { cpuset, possible, fail } state = cpuset;
+	int dest_cpu;
+
+	/*
+	 * If the node that the CPU is on has been offlined, cpu_to_node()
+	 * will return -1. There is no CPU on the node, and we should
+	 * select the CPU on the other node.
+	 */
+	if (nid != -1) {
+		nodemask = cpumask_of_node(nid);
+
+		/* Look for allowed, online CPU in same node. */
+		for_each_cpu(dest_cpu, nodemask) {
+			if (!cpu_active(dest_cpu))
+				continue;
+			if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
+				return dest_cpu;
+		}
+	}
+
+	for (;;) {
+		/* Any allowed, online CPU? */
+		for_each_cpu(dest_cpu, &p->cpus_allowed) {
+			if (!is_cpu_allowed(p, dest_cpu))
+				continue;
+
+			goto out;
+		}
+
+		/* No more Mr. Nice Guy. */
+		switch (state) {
+		case cpuset:
+			if (IS_ENABLED(CONFIG_CPUSETS)) {
+				cpuset_cpus_allowed_fallback(p);
+				state = possible;
+				break;
+			}
+			/* Fall-through */
+		case possible:
+			do_set_cpus_allowed(p, cpu_possible_mask);
+			state = fail;
+			break;
+
+		case fail:
+			BUG();
+			break;
+		}
+	}
+
+out:
+	if (state != cpuset) {
+		/*
+		 * Don't tell them about moving exiting tasks or
+		 * kernel threads (both mm NULL), since they never
+		 * leave kernel.
+		 */
+		if (p->mm && printk_ratelimit()) {
+			printk_deferred("process %d (%s) no longer affine to cpu%d\n",
+					task_pid_nr(p), p->comm, cpu);
+		}
+	}
+
+	return dest_cpu;
+}
+
+/*
+ * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
+ */
+static inline
+int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags)
+{
+	lockdep_assert_held(&p->pi_lock);
+
+	if (p->nr_cpus_allowed > 1)
+		cpu = p->sched_class->select_task_rq(p, cpu, sd_flags, wake_flags);
+	else
+		cpu = cpumask_any(&p->cpus_allowed);
+
+	/*
+	 * In order not to call set_task_cpu() on a blocking task we need
+	 * to rely on ttwu() to place the task on a valid ->cpus_allowed
+	 * CPU.
+	 *
+	 * Since this is common to all placement strategies, this lives here.
+	 *
+	 * [ this allows ->select_task() to simply return task_cpu(p) and
+	 *   not worry about this generic constraint ]
+	 */
+	if (unlikely(!is_cpu_allowed(p, cpu)))
+		cpu = select_fallback_rq(task_cpu(p), p);
+
+	return cpu;
+}
+
+static void update_avg(u64 *avg, u64 sample)
+{
+	s64 diff = sample - *avg;
+	*avg += diff >> 3;
+}
+
+void sched_set_stop_task(int cpu, struct task_struct *stop)
+{
+	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
+	struct task_struct *old_stop = cpu_rq(cpu)->stop;
+
+	if (stop) {
+		/*
+		 * Make it appear like a SCHED_FIFO task, its something
+		 * userspace knows about and won't get confused about.
+		 *
+		 * Also, it will make PI more or less work without too
+		 * much confusion -- but then, stop work should not
+		 * rely on PI working anyway.
+		 */
+		sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
+
+		stop->sched_class = &stop_sched_class;
+	}
+
+	cpu_rq(cpu)->stop = stop;
+
+	if (old_stop) {
+		/*
+		 * Reset it back to a normal scheduling class so that
+		 * it can die in pieces.
+		 */
+		old_stop->sched_class = &rt_sched_class;
+	}
+}
+
+#else
+
+static inline int __set_cpus_allowed_ptr(struct task_struct *p,
+					 const struct cpumask *new_mask, bool check)
+{
+	return set_cpus_allowed_ptr(p, new_mask);
+}
+
+#endif /* CONFIG_SMP */
+
+static void
+ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
+{
+	struct rq *rq;
+
+	if (!schedstat_enabled())
+		return;
+
+	rq = this_rq();
+
+#ifdef CONFIG_SMP
+	if (cpu == rq->cpu) {
+		__schedstat_inc(rq->ttwu_local);
+		__schedstat_inc(p->se.statistics.nr_wakeups_local);
+	} else {
+		struct sched_domain *sd;
+
+		__schedstat_inc(p->se.statistics.nr_wakeups_remote);
+		rcu_read_lock();
+		for_each_domain(rq->cpu, sd) {
+			if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
+				__schedstat_inc(sd->ttwu_wake_remote);
+				break;
+			}
+		}
+		rcu_read_unlock();
+	}
+
+	if (wake_flags & WF_MIGRATED)
+		__schedstat_inc(p->se.statistics.nr_wakeups_migrate);
+#endif /* CONFIG_SMP */
+
+	__schedstat_inc(rq->ttwu_count);
+	__schedstat_inc(p->se.statistics.nr_wakeups);
+
+	if (wake_flags & WF_SYNC)
+		__schedstat_inc(p->se.statistics.nr_wakeups_sync);
+}
+
+static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
+{
+	activate_task(rq, p, en_flags);
+	p->on_rq = TASK_ON_RQ_QUEUED;
+
+	/* If a worker is waking up, notify the workqueue: */
+	if (p->flags & PF_WQ_WORKER)
+		wq_worker_waking_up(p, cpu_of(rq));
+}
+
+/*
+ * Mark the task runnable and perform wakeup-preemption.
+ */
+static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags,
+			   struct rq_flags *rf)
+{
+	check_preempt_curr(rq, p, wake_flags);
+	p->state = TASK_RUNNING;
+	trace_sched_wakeup(p);
+
+#ifdef CONFIG_SMP
+	if (p->sched_class->task_woken) {
+		/*
+		 * Our task @p is fully woken up and running; so its safe to
+		 * drop the rq->lock, hereafter rq is only used for statistics.
+		 */
+		rq_unpin_lock(rq, rf);
+		p->sched_class->task_woken(rq, p);
+		rq_repin_lock(rq, rf);
+	}
+
+	if (rq->idle_stamp) {
+		u64 delta = rq_clock(rq) - rq->idle_stamp;
+		u64 max = 2*rq->max_idle_balance_cost;
+
+		update_avg(&rq->avg_idle, delta);
+
+		if (rq->avg_idle > max)
+			rq->avg_idle = max;
+
+		rq->idle_stamp = 0;
+	}
+#endif
+}
+
+static void
+ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
+		 struct rq_flags *rf)
+{
+	int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK;
+
+	lockdep_assert_held(&rq->lock);
+
+#ifdef CONFIG_SMP
+	if (p->sched_contributes_to_load)
+		rq->nr_uninterruptible--;
+
+	if (wake_flags & WF_MIGRATED)
+		en_flags |= ENQUEUE_MIGRATED;
+#endif
+
+	ttwu_activate(rq, p, en_flags);
+	ttwu_do_wakeup(rq, p, wake_flags, rf);
+}
+
+/*
+ * Called in case the task @p isn't fully descheduled from its runqueue,
+ * in this case we must do a remote wakeup. Its a 'light' wakeup though,
+ * since all we need to do is flip p->state to TASK_RUNNING, since
+ * the task is still ->on_rq.
+ */
+static int ttwu_remote(struct task_struct *p, int wake_flags)
+{
+	struct rq_flags rf;
+	struct rq *rq;
+	int ret = 0;
+
+	rq = __task_rq_lock(p, &rf);
+	if (task_on_rq_queued(p)) {
+		/* check_preempt_curr() may use rq clock */
+		update_rq_clock(rq);
+		ttwu_do_wakeup(rq, p, wake_flags, &rf);
+		ret = 1;
+	}
+	__task_rq_unlock(rq, &rf);
+
+	return ret;
+}
+
+#ifdef CONFIG_SMP
+void sched_ttwu_pending(void)
+{
+	struct rq *rq = this_rq();
+	struct llist_node *llist = llist_del_all(&rq->wake_list);
+	struct task_struct *p, *t;
+	struct rq_flags rf;
+
+	if (!llist)
+		return;
+
+	rq_lock_irqsave(rq, &rf);
+	update_rq_clock(rq);
+
+	llist_for_each_entry_safe(p, t, llist, wake_entry)
+		ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf);
+
+	rq_unlock_irqrestore(rq, &rf);
+}
+
+void scheduler_ipi(void)
+{
+	/*
+	 * Fold TIF_NEED_RESCHED into the preempt_count; anybody setting
+	 * TIF_NEED_RESCHED remotely (for the first time) will also send
+	 * this IPI.
+	 */
+	preempt_fold_need_resched();
+
+	if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
+		return;
+
+	/*
+	 * Not all reschedule IPI handlers call irq_enter/irq_exit, since
+	 * traditionally all their work was done from the interrupt return
+	 * path. Now that we actually do some work, we need to make sure
+	 * we do call them.
+	 *
+	 * Some archs already do call them, luckily irq_enter/exit nest
+	 * properly.
+	 *
+	 * Arguably we should visit all archs and update all handlers,
+	 * however a fair share of IPIs are still resched only so this would
+	 * somewhat pessimize the simple resched case.
+	 */
+	irq_enter();
+	sched_ttwu_pending();
+
+	/*
+	 * Check if someone kicked us for doing the nohz idle load balance.
+	 */
+	if (unlikely(got_nohz_idle_kick())) {
+		this_rq()->idle_balance = 1;
+		raise_softirq_irqoff(SCHED_SOFTIRQ);
+	}
+	irq_exit();
+}
+
+static void ttwu_queue_remote(struct task_struct *p, int cpu, int wake_flags)
+{
+	struct rq *rq = cpu_rq(cpu);
+
+	p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
+
+	if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list)) {
+		if (!set_nr_if_polling(rq->idle))
+			smp_send_reschedule(cpu);
+		else
+			trace_sched_wake_idle_without_ipi(cpu);
+	}
+}
+
+void wake_up_if_idle(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	struct rq_flags rf;
+
+	rcu_read_lock();
+
+	if (!is_idle_task(rcu_dereference(rq->curr)))
+		goto out;
+
+	if (set_nr_if_polling(rq->idle)) {
+		trace_sched_wake_idle_without_ipi(cpu);
+	} else {
+		rq_lock_irqsave(rq, &rf);
+		if (is_idle_task(rq->curr))
+			smp_send_reschedule(cpu);
+		/* Else CPU is not idle, do nothing here: */
+		rq_unlock_irqrestore(rq, &rf);
+	}
+
+out:
+	rcu_read_unlock();
+}
+
+bool cpus_share_cache(int this_cpu, int that_cpu)
+{
+	if (this_cpu == that_cpu)
+		return true;
+
+	return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
+}
+#endif /* CONFIG_SMP */
+
+static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
+{
+	struct rq *rq = cpu_rq(cpu);
+	struct rq_flags rf;
+
+#if defined(CONFIG_SMP)
+	if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
+		sched_clock_cpu(cpu); /* Sync clocks across CPUs */
+		ttwu_queue_remote(p, cpu, wake_flags);
+		return;
+	}
+#endif
+
+	rq_lock(rq, &rf);
+	update_rq_clock(rq);
+	ttwu_do_activate(rq, p, wake_flags, &rf);
+	rq_unlock(rq, &rf);
+}
+
+/*
+ * Notes on Program-Order guarantees on SMP systems.
+ *
+ *  MIGRATION
+ *
+ * The basic program-order guarantee on SMP systems is that when a task [t]
+ * migrates, all its activity on its old CPU [c0] happens-before any subsequent
+ * execution on its new CPU [c1].
+ *
+ * For migration (of runnable tasks) this is provided by the following means:
+ *
+ *  A) UNLOCK of the rq(c0)->lock scheduling out task t
+ *  B) migration for t is required to synchronize *both* rq(c0)->lock and
+ *     rq(c1)->lock (if not at the same time, then in that order).
+ *  C) LOCK of the rq(c1)->lock scheduling in task
+ *
+ * Release/acquire chaining guarantees that B happens after A and C after B.
+ * Note: the CPU doing B need not be c0 or c1
+ *
+ * Example:
+ *
+ *   CPU0            CPU1            CPU2
+ *
+ *   LOCK rq(0)->lock
+ *   sched-out X
+ *   sched-in Y
+ *   UNLOCK rq(0)->lock
+ *
+ *                                   LOCK rq(0)->lock // orders against CPU0
+ *                                   dequeue X
+ *                                   UNLOCK rq(0)->lock
+ *
+ *                                   LOCK rq(1)->lock
+ *                                   enqueue X
+ *                                   UNLOCK rq(1)->lock
+ *
+ *                   LOCK rq(1)->lock // orders against CPU2
+ *                   sched-out Z
+ *                   sched-in X
+ *                   UNLOCK rq(1)->lock
+ *
+ *
+ *  BLOCKING -- aka. SLEEP + WAKEUP
+ *
+ * For blocking we (obviously) need to provide the same guarantee as for
+ * migration. However the means are completely different as there is no lock
+ * chain to provide order. Instead we do:
+ *
+ *   1) smp_store_release(X->on_cpu, 0)
+ *   2) smp_cond_load_acquire(!X->on_cpu)
+ *
+ * Example:
+ *
+ *   CPU0 (schedule)  CPU1 (try_to_wake_up) CPU2 (schedule)
+ *
+ *   LOCK rq(0)->lock LOCK X->pi_lock
+ *   dequeue X
+ *   sched-out X
+ *   smp_store_release(X->on_cpu, 0);
+ *
+ *                    smp_cond_load_acquire(&X->on_cpu, !VAL);
+ *                    X->state = WAKING
+ *                    set_task_cpu(X,2)
+ *
+ *                    LOCK rq(2)->lock
+ *                    enqueue X
+ *                    X->state = RUNNING
+ *                    UNLOCK rq(2)->lock
+ *
+ *                                          LOCK rq(2)->lock // orders against CPU1
+ *                                          sched-out Z
+ *                                          sched-in X
+ *                                          UNLOCK rq(2)->lock
+ *
+ *                    UNLOCK X->pi_lock
+ *   UNLOCK rq(0)->lock
+ *
+ *
+ * However, for wakeups there is a second guarantee we must provide, namely we
+ * must ensure that CONDITION=1 done by the caller can not be reordered with
+ * accesses to the task state; see try_to_wake_up() and set_current_state().
+ */
+
+/**
+ * try_to_wake_up - wake up a thread
+ * @p: the thread to be awakened
+ * @state: the mask of task states that can be woken
+ * @wake_flags: wake modifier flags (WF_*)
+ *
+ * If (@state & @p->state) @p->state = TASK_RUNNING.
+ *
+ * If the task was not queued/runnable, also place it back on a runqueue.
+ *
+ * Atomic against schedule() which would dequeue a task, also see
+ * set_current_state().
+ *
+ * This function executes a full memory barrier before accessing the task
+ * state; see set_current_state().
+ *
+ * Return: %true if @p->state changes (an actual wakeup was done),
+ *	   %false otherwise.
+ */
+static int
+try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
+{
+	unsigned long flags;
+	int cpu, success = 0;
+
+	/*
+	 * If we are going to wake up a thread waiting for CONDITION we
+	 * need to ensure that CONDITION=1 done by the caller can not be
+	 * reordered with p->state check below. This pairs with mb() in
+	 * set_current_state() the waiting thread does.
+	 */
+	raw_spin_lock_irqsave(&p->pi_lock, flags);
+	smp_mb__after_spinlock();
+	if (!(p->state & state))
+		goto out;
+
+	trace_sched_waking(p);
+
+	/* We're going to change ->state: */
+	success = 1;
+	cpu = task_cpu(p);
+
+	/*
+	 * Ensure we load p->on_rq _after_ p->state, otherwise it would
+	 * be possible to, falsely, observe p->on_rq == 0 and get stuck
+	 * in smp_cond_load_acquire() below.
+	 *
+	 * sched_ttwu_pending()			try_to_wake_up()
+	 *   STORE p->on_rq = 1			  LOAD p->state
+	 *   UNLOCK rq->lock
+	 *
+	 * __schedule() (switch to task 'p')
+	 *   LOCK rq->lock			  smp_rmb();
+	 *   smp_mb__after_spinlock();
+	 *   UNLOCK rq->lock
+	 *
+	 * [task p]
+	 *   STORE p->state = UNINTERRUPTIBLE	  LOAD p->on_rq
+	 *
+	 * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
+	 * __schedule().  See the comment for smp_mb__after_spinlock().
+	 */
+	smp_rmb();
+	if (p->on_rq && ttwu_remote(p, wake_flags))
+		goto stat;
+
+#ifdef CONFIG_SMP
+	/*
+	 * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
+	 * possible to, falsely, observe p->on_cpu == 0.
+	 *
+	 * One must be running (->on_cpu == 1) in order to remove oneself
+	 * from the runqueue.
+	 *
+	 * __schedule() (switch to task 'p')	try_to_wake_up()
+	 *   STORE p->on_cpu = 1		  LOAD p->on_rq
+	 *   UNLOCK rq->lock
+	 *
+	 * __schedule() (put 'p' to sleep)
+	 *   LOCK rq->lock			  smp_rmb();
+	 *   smp_mb__after_spinlock();
+	 *   STORE p->on_rq = 0			  LOAD p->on_cpu
+	 *
+	 * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
+	 * __schedule().  See the comment for smp_mb__after_spinlock().
+	 */
+	smp_rmb();
+
+	/*
+	 * If the owning (remote) CPU is still in the middle of schedule() with
+	 * this task as prev, wait until its done referencing the task.
+	 *
+	 * Pairs with the smp_store_release() in finish_task().
+	 *
+	 * This ensures that tasks getting woken will be fully ordered against
+	 * their previous state and preserve Program Order.
+	 */
+	smp_cond_load_acquire(&p->on_cpu, !VAL);
+
+	p->sched_contributes_to_load = !!task_contributes_to_load(p);
+	p->state = TASK_WAKING;
+
+	if (p->in_iowait) {
+		delayacct_blkio_end(p);
+		atomic_dec(&task_rq(p)->nr_iowait);
+	}
+
+	cpu = select_task_rq(p, p->wake_cpu, SD_BALANCE_WAKE, wake_flags);
+	if (task_cpu(p) != cpu) {
+		wake_flags |= WF_MIGRATED;
+		set_task_cpu(p, cpu);
+	}
+
+#else /* CONFIG_SMP */
+
+	if (p->in_iowait) {
+		delayacct_blkio_end(p);
+		atomic_dec(&task_rq(p)->nr_iowait);
+	}
+
+#endif /* CONFIG_SMP */
+
+	ttwu_queue(p, cpu, wake_flags);
+stat:
+	ttwu_stat(p, cpu, wake_flags);
+out:
+	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+
+	return success;
+}
+
+/**
+ * try_to_wake_up_local - try to wake up a local task with rq lock held
+ * @p: the thread to be awakened
+ * @rf: request-queue flags for pinning
+ *
+ * Put @p on the run-queue if it's not already there. The caller must
+ * ensure that this_rq() is locked, @p is bound to this_rq() and not
+ * the current task.
+ */
+static void try_to_wake_up_local(struct task_struct *p, struct rq_flags *rf)
+{
+	struct rq *rq = task_rq(p);
+
+	if (WARN_ON_ONCE(rq != this_rq()) ||
+	    WARN_ON_ONCE(p == current))
+		return;
+
+	lockdep_assert_held(&rq->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.
+		 */
+		rq_unlock(rq, rf);
+		raw_spin_lock(&p->pi_lock);
+		rq_relock(rq, rf);
+	}
+
+	if (!(p->state & TASK_NORMAL))
+		goto out;
+
+	trace_sched_waking(p);
+
+	if (!task_on_rq_queued(p)) {
+		if (p->in_iowait) {
+			delayacct_blkio_end(p);
+			atomic_dec(&rq->nr_iowait);
+		}
+		ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK);
+	}
+
+	ttwu_do_wakeup(rq, p, 0, rf);
+	ttwu_stat(p, smp_processor_id(), 0);
+out:
+	raw_spin_unlock(&p->pi_lock);
+}
+
+/**
+ * wake_up_process - Wake up a specific process
+ * @p: The process to be woken up.
+ *
+ * Attempt to wake up the nominated process and move it to the set of runnable
+ * processes.
+ *
+ * Return: 1 if the process was woken up, 0 if it was already running.
+ *
+ * This function executes a full memory barrier before accessing the task state.
+ */
+int wake_up_process(struct task_struct *p)
+{
+	return try_to_wake_up(p, TASK_NORMAL, 0);
+}
+EXPORT_SYMBOL(wake_up_process);
+
+int wake_up_state(struct task_struct *p, unsigned int state)
+{
+	return try_to_wake_up(p, state, 0);
+}
+
+/*
+ * Perform scheduler related setup for a newly forked process p.
+ * p is forked by current.
+ *
+ * __sched_fork() is basic setup used by init_idle() too:
+ */
+static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
+{
+	p->on_rq			= 0;
+
+	p->se.on_rq			= 0;
+	p->se.exec_start		= 0;
+	p->se.sum_exec_runtime		= 0;
+	p->se.prev_sum_exec_runtime	= 0;
+	p->se.nr_migrations		= 0;
+	p->se.vruntime			= 0;
+	INIT_LIST_HEAD(&p->se.group_node);
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+	p->se.cfs_rq			= NULL;
+#endif
+
+#ifdef CONFIG_SCHEDSTATS
+	/* Even if schedstat is disabled, there should not be garbage */
+	memset(&p->se.statistics, 0, sizeof(p->se.statistics));
+#endif
+
+	RB_CLEAR_NODE(&p->dl.rb_node);
+	init_dl_task_timer(&p->dl);
+	init_dl_inactive_task_timer(&p->dl);
+	__dl_clear_params(p);
+
+	INIT_LIST_HEAD(&p->rt.run_list);
+	p->rt.timeout		= 0;
+	p->rt.time_slice	= sched_rr_timeslice;
+	p->rt.on_rq		= 0;
+	p->rt.on_list		= 0;
+
+#ifdef CONFIG_PREEMPT_NOTIFIERS
+	INIT_HLIST_HEAD(&p->preempt_notifiers);
+#endif
+
+	init_numa_balancing(clone_flags, p);
+}
+
+DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
+
+#ifdef CONFIG_NUMA_BALANCING
+
+void set_numabalancing_state(bool enabled)
+{
+	if (enabled)
+		static_branch_enable(&sched_numa_balancing);
+	else
+		static_branch_disable(&sched_numa_balancing);
+}
+
+#ifdef CONFIG_PROC_SYSCTL
+int sysctl_numa_balancing(struct ctl_table *table, int write,
+			 void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct ctl_table t;
+	int err;
+	int state = static_branch_likely(&sched_numa_balancing);
+
+	if (write && !capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	t = *table;
+	t.data = &state;
+	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
+	if (err < 0)
+		return err;
+	if (write)
+		set_numabalancing_state(state);
+	return err;
+}
+#endif
+#endif
+
+#ifdef CONFIG_SCHEDSTATS
+
+DEFINE_STATIC_KEY_FALSE(sched_schedstats);
+static bool __initdata __sched_schedstats = false;
+
+static void set_schedstats(bool enabled)
+{
+	if (enabled)
+		static_branch_enable(&sched_schedstats);
+	else
+		static_branch_disable(&sched_schedstats);
+}
+
+void force_schedstat_enabled(void)
+{
+	if (!schedstat_enabled()) {
+		pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
+		static_branch_enable(&sched_schedstats);
+	}
+}
+
+static int __init setup_schedstats(char *str)
+{
+	int ret = 0;
+	if (!str)
+		goto out;
+
+	/*
+	 * This code is called before jump labels have been set up, so we can't
+	 * change the static branch directly just yet.  Instead set a temporary
+	 * variable so init_schedstats() can do it later.
+	 */
+	if (!strcmp(str, "enable")) {
+		__sched_schedstats = true;
+		ret = 1;
+	} else if (!strcmp(str, "disable")) {
+		__sched_schedstats = false;
+		ret = 1;
+	}
+out:
+	if (!ret)
+		pr_warn("Unable to parse schedstats=\n");
+
+	return ret;
+}
+__setup("schedstats=", setup_schedstats);
+
+static void __init init_schedstats(void)
+{
+	set_schedstats(__sched_schedstats);
+}
+
+#ifdef CONFIG_PROC_SYSCTL
+int sysctl_schedstats(struct ctl_table *table, int write,
+			 void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct ctl_table t;
+	int err;
+	int state = static_branch_likely(&sched_schedstats);
+
+	if (write && !capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	t = *table;
+	t.data = &state;
+	err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
+	if (err < 0)
+		return err;
+	if (write)
+		set_schedstats(state);
+	return err;
+}
+#endif /* CONFIG_PROC_SYSCTL */
+#else  /* !CONFIG_SCHEDSTATS */
+static inline void init_schedstats(void) {}
+#endif /* CONFIG_SCHEDSTATS */
+
+/*
+ * fork()/clone()-time setup:
+ */
+int sched_fork(unsigned long clone_flags, struct task_struct *p)
+{
+	unsigned long flags;
+
+	__sched_fork(clone_flags, p);
+	/*
+	 * We mark the process as NEW here. This guarantees that
+	 * nobody will actually run it, and a signal or other external
+	 * event cannot wake it up and insert it on the runqueue either.
+	 */
+	p->state = TASK_NEW;
+
+	/*
+	 * Make sure we do not leak PI boosting priority to the child.
+	 */
+	p->prio = current->normal_prio;
+
+	/*
+	 * Revert to default priority/policy on fork if requested.
+	 */
+	if (unlikely(p->sched_reset_on_fork)) {
+		if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
+			p->policy = SCHED_NORMAL;
+			p->static_prio = NICE_TO_PRIO(0);
+			p->rt_priority = 0;
+		} else if (PRIO_TO_NICE(p->static_prio) < 0)
+			p->static_prio = NICE_TO_PRIO(0);
+
+		p->prio = p->normal_prio = __normal_prio(p);
+		set_load_weight(p, false);
+
+		/*
+		 * We don't need the reset flag anymore after the fork. It has
+		 * fulfilled its duty:
+		 */
+		p->sched_reset_on_fork = 0;
+	}
+
+	if (dl_prio(p->prio))
+		return -EAGAIN;
+	else if (rt_prio(p->prio))
+		p->sched_class = &rt_sched_class;
+	else
+		p->sched_class = &fair_sched_class;
+
+	init_entity_runnable_average(&p->se);
+
+	/*
+	 * The child is not yet in the pid-hash so no cgroup attach races,
+	 * and the cgroup is pinned to this child due to cgroup_fork()
+	 * is ran before sched_fork().
+	 *
+	 * Silence PROVE_RCU.
+	 */
+	raw_spin_lock_irqsave(&p->pi_lock, flags);
+	rseq_migrate(p);
+	/*
+	 * We're setting the CPU for the first time, we don't migrate,
+	 * so use __set_task_cpu().
+	 */
+	__set_task_cpu(p, smp_processor_id());
+	if (p->sched_class->task_fork)
+		p->sched_class->task_fork(p);
+	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+
+#ifdef CONFIG_SCHED_INFO
+	if (likely(sched_info_on()))
+		memset(&p->sched_info, 0, sizeof(p->sched_info));
+#endif
+#if defined(CONFIG_SMP)
+	p->on_cpu = 0;
+#endif
+	init_task_preempt_count(p);
+#ifdef CONFIG_SMP
+	plist_node_init(&p->pushable_tasks, MAX_PRIO);
+	RB_CLEAR_NODE(&p->pushable_dl_tasks);
+#endif
+	return 0;
+}
+
+unsigned long to_ratio(u64 period, u64 runtime)
+{
+	if (runtime == RUNTIME_INF)
+		return BW_UNIT;
+
+	/*
+	 * Doing this here saves a lot of checks in all
+	 * the calling paths, and returning zero seems
+	 * safe for them anyway.
+	 */
+	if (period == 0)
+		return 0;
+
+	return div64_u64(runtime << BW_SHIFT, period);
+}
+
+/*
+ * wake_up_new_task - wake up a newly created task for the first time.
+ *
+ * This function will do some initial scheduler statistics housekeeping
+ * that must be done for every newly created context, then puts the task
+ * on the runqueue and wakes it.
+ */
+void wake_up_new_task(struct task_struct *p)
+{
+	struct rq_flags rf;
+	struct rq *rq;
+
+	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
+	p->state = TASK_RUNNING;
+#ifdef CONFIG_SMP
+	/*
+	 * Fork balancing, do it here and not earlier because:
+	 *  - cpus_allowed can change in the fork path
+	 *  - any previously selected CPU might disappear through hotplug
+	 *
+	 * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq,
+	 * as we're not fully set-up yet.
+	 */
+	p->recent_used_cpu = task_cpu(p);
+	rseq_migrate(p);
+	__set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0));
+#endif
+	rq = __task_rq_lock(p, &rf);
+	update_rq_clock(rq);
+	post_init_entity_util_avg(&p->se);
+
+	activate_task(rq, p, ENQUEUE_NOCLOCK);
+	p->on_rq = TASK_ON_RQ_QUEUED;
+	trace_sched_wakeup_new(p);
+	check_preempt_curr(rq, p, WF_FORK);
+#ifdef CONFIG_SMP
+	if (p->sched_class->task_woken) {
+		/*
+		 * Nothing relies on rq->lock after this, so its fine to
+		 * drop it.
+		 */
+		rq_unpin_lock(rq, &rf);
+		p->sched_class->task_woken(rq, p);
+		rq_repin_lock(rq, &rf);
+	}
+#endif
+	task_rq_unlock(rq, p, &rf);
+}
+
+#ifdef CONFIG_PREEMPT_NOTIFIERS
+
+static DEFINE_STATIC_KEY_FALSE(preempt_notifier_key);
+
+void preempt_notifier_inc(void)
+{
+	static_branch_inc(&preempt_notifier_key);
+}
+EXPORT_SYMBOL_GPL(preempt_notifier_inc);
+
+void preempt_notifier_dec(void)
+{
+	static_branch_dec(&preempt_notifier_key);
+}
+EXPORT_SYMBOL_GPL(preempt_notifier_dec);
+
+/**
+ * preempt_notifier_register - tell me when current is being preempted & rescheduled
+ * @notifier: notifier struct to register
+ */
+void preempt_notifier_register(struct preempt_notifier *notifier)
+{
+	if (!static_branch_unlikely(&preempt_notifier_key))
+		WARN(1, "registering preempt_notifier while notifiers disabled\n");
+
+	hlist_add_head(&notifier->link, &current->preempt_notifiers);
+}
+EXPORT_SYMBOL_GPL(preempt_notifier_register);
+
+/**
+ * preempt_notifier_unregister - no longer interested in preemption notifications
+ * @notifier: notifier struct to unregister
+ *
+ * This is *not* safe to call from within a preemption notifier.
+ */
+void preempt_notifier_unregister(struct preempt_notifier *notifier)
+{
+	hlist_del(&notifier->link);
+}
+EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
+
+static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
+{
+	struct preempt_notifier *notifier;
+
+	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
+		notifier->ops->sched_in(notifier, raw_smp_processor_id());
+}
+
+static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
+{
+	if (static_branch_unlikely(&preempt_notifier_key))
+		__fire_sched_in_preempt_notifiers(curr);
+}
+
+static void
+__fire_sched_out_preempt_notifiers(struct task_struct *curr,
+				   struct task_struct *next)
+{
+	struct preempt_notifier *notifier;
+
+	hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
+		notifier->ops->sched_out(notifier, next);
+}
+
+static __always_inline void
+fire_sched_out_preempt_notifiers(struct task_struct *curr,
+				 struct task_struct *next)
+{
+	if (static_branch_unlikely(&preempt_notifier_key))
+		__fire_sched_out_preempt_notifiers(curr, next);
+}
+
+#else /* !CONFIG_PREEMPT_NOTIFIERS */
+
+static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
+{
+}
+
+static inline void
+fire_sched_out_preempt_notifiers(struct task_struct *curr,
+				 struct task_struct *next)
+{
+}
+
+#endif /* CONFIG_PREEMPT_NOTIFIERS */
+
+static inline void prepare_task(struct task_struct *next)
+{
+#ifdef CONFIG_SMP
+	/*
+	 * Claim the task as running, we do this before switching to it
+	 * such that any running task will have this set.
+	 */
+	next->on_cpu = 1;
+#endif
+}
+
+static inline void finish_task(struct task_struct *prev)
+{
+#ifdef CONFIG_SMP
+	/*
+	 * After ->on_cpu is cleared, the task can be moved to a different CPU.
+	 * We must ensure this doesn't happen until the switch is completely
+	 * finished.
+	 *
+	 * In particular, the load of prev->state in finish_task_switch() must
+	 * happen before this.
+	 *
+	 * Pairs with the smp_cond_load_acquire() in try_to_wake_up().
+	 */
+	smp_store_release(&prev->on_cpu, 0);
+#endif
+}
+
+static inline void
+prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf)
+{
+	/*
+	 * Since the runqueue lock will be released by the next
+	 * task (which is an invalid locking op but in the case
+	 * of the scheduler it's an obvious special-case), so we
+	 * do an early lockdep release here:
+	 */
+	rq_unpin_lock(rq, rf);
+	spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
+#ifdef CONFIG_DEBUG_SPINLOCK
+	/* this is a valid case when another task releases the spinlock */
+	rq->lock.owner = next;
+#endif
+}
+
+static inline void finish_lock_switch(struct rq *rq)
+{
+	/*
+	 * If we are tracking spinlock dependencies then we have to
+	 * fix up the runqueue lock - which gets 'carried over' from
+	 * prev into current:
+	 */
+	spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
+	raw_spin_unlock_irq(&rq->lock);
+}
+
+/*
+ * NOP if the arch has not defined these:
+ */
+
+#ifndef prepare_arch_switch
+# define prepare_arch_switch(next)	do { } while (0)
+#endif
+
+#ifndef finish_arch_post_lock_switch
+# define finish_arch_post_lock_switch()	do { } while (0)
+#endif
+
+/**
+ * prepare_task_switch - prepare to switch tasks
+ * @rq: the runqueue preparing to switch
+ * @prev: the current task that is being switched out
+ * @next: the task we are going to switch to.
+ *
+ * This is called with the rq lock held and interrupts off. It must
+ * be paired with a subsequent finish_task_switch after the context
+ * switch.
+ *
+ * prepare_task_switch sets up locking and calls architecture specific
+ * hooks.
+ */
+static inline void
+prepare_task_switch(struct rq *rq, struct task_struct *prev,
+		    struct task_struct *next)
+{
+	kcov_prepare_switch(prev);
+	sched_info_switch(rq, prev, next);
+	perf_event_task_sched_out(prev, next);
+	rseq_preempt(prev);
+	fire_sched_out_preempt_notifiers(prev, next);
+	prepare_task(next);
+	prepare_arch_switch(next);
+}
+
+/**
+ * finish_task_switch - clean up after a task-switch
+ * @prev: the thread we just switched away from.
+ *
+ * finish_task_switch must be called after the context switch, paired
+ * with a prepare_task_switch call before the context switch.
+ * finish_task_switch will reconcile locking set up by prepare_task_switch,
+ * and do any other architecture-specific cleanup actions.
+ *
+ * Note that we may have delayed dropping an mm in context_switch(). If
+ * so, we finish that here outside of the runqueue lock. (Doing it
+ * with the lock held can cause deadlocks; see schedule() for
+ * details.)
+ *
+ * The context switch have flipped the stack from under us and restored the
+ * local variables which were saved when this task called schedule() in the
+ * past. prev == current is still correct but we need to recalculate this_rq
+ * because prev may have moved to another CPU.
+ */
+static struct rq *finish_task_switch(struct task_struct *prev)
+	__releases(rq->lock)
+{
+	struct rq *rq = this_rq();
+	struct mm_struct *mm = rq->prev_mm;
+	long prev_state;
+
+	/*
+	 * The previous task will have left us with a preempt_count of 2
+	 * because it left us after:
+	 *
+	 *	schedule()
+	 *	  preempt_disable();			// 1
+	 *	  __schedule()
+	 *	    raw_spin_lock_irq(&rq->lock)	// 2
+	 *
+	 * Also, see FORK_PREEMPT_COUNT.
+	 */
+	if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
+		      "corrupted preempt_count: %s/%d/0x%x\n",
+		      current->comm, current->pid, preempt_count()))
+		preempt_count_set(FORK_PREEMPT_COUNT);
+
+	rq->prev_mm = NULL;
+
+	/*
+	 * A task struct has one reference for the use as "current".
+	 * If a task dies, then it sets TASK_DEAD in tsk->state and calls
+	 * schedule one last time. The schedule call will never return, and
+	 * the scheduled task must drop that reference.
+	 *
+	 * We must observe prev->state before clearing prev->on_cpu (in
+	 * finish_task), otherwise a concurrent wakeup can get prev
+	 * running on another CPU and we could rave with its RUNNING -> DEAD
+	 * transition, resulting in a double drop.
+	 */
+	prev_state = prev->state;
+	vtime_task_switch(prev);
+	perf_event_task_sched_in(prev, current);
+	finish_task(prev);
+	finish_lock_switch(rq);
+	finish_arch_post_lock_switch();
+	kcov_finish_switch(current);
+
+	fire_sched_in_preempt_notifiers(current);
+	/*
+	 * When switching through a kernel thread, the loop in
+	 * membarrier_{private,global}_expedited() may have observed that
+	 * kernel thread and not issued an IPI. It is therefore possible to
+	 * schedule between user->kernel->user threads without passing though
+	 * switch_mm(). Membarrier requires a barrier after storing to
+	 * rq->curr, before returning to userspace, so provide them here:
+	 *
+	 * - a full memory barrier for {PRIVATE,GLOBAL}_EXPEDITED, implicitly
+	 *   provided by mmdrop(),
+	 * - a sync_core for SYNC_CORE.
+	 */
+	if (mm) {
+		membarrier_mm_sync_core_before_usermode(mm);
+		mmdrop(mm);
+	}
+	if (unlikely(prev_state == TASK_DEAD)) {
+		if (prev->sched_class->task_dead)
+			prev->sched_class->task_dead(prev);
+
+		/*
+		 * Remove function-return probe instances associated with this
+		 * task and put them back on the free list.
+		 */
+		kprobe_flush_task(prev);
+
+		/* Task is done with its stack. */
+		put_task_stack(prev);
+
+		put_task_struct(prev);
+	}
+
+	tick_nohz_task_switch();
+	return rq;
+}
+
+#ifdef CONFIG_SMP
+
+/* rq->lock is NOT held, but preemption is disabled */
+static void __balance_callback(struct rq *rq)
+{
+	struct callback_head *head, *next;
+	void (*func)(struct rq *rq);
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&rq->lock, flags);
+	head = rq->balance_callback;
+	rq->balance_callback = NULL;
+	while (head) {
+		func = (void (*)(struct rq *))head->func;
+		next = head->next;
+		head->next = NULL;
+		head = next;
+
+		func(rq);
+	}
+	raw_spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+static inline void balance_callback(struct rq *rq)
+{
+	if (unlikely(rq->balance_callback))
+		__balance_callback(rq);
+}
+
+#else
+
+static inline void balance_callback(struct rq *rq)
+{
+}
+
+#endif
+
+/**
+ * schedule_tail - first thing a freshly forked thread must call.
+ * @prev: the thread we just switched away from.
+ */
+asmlinkage __visible void schedule_tail(struct task_struct *prev)
+	__releases(rq->lock)
+{
+	struct rq *rq;
+
+	/*
+	 * New tasks start with FORK_PREEMPT_COUNT, see there and
+	 * finish_task_switch() for details.
+	 *
+	 * finish_task_switch() will drop rq->lock() and lower preempt_count
+	 * and the preempt_enable() will end up enabling preemption (on
+	 * PREEMPT_COUNT kernels).
+	 */
+
+	rq = finish_task_switch(prev);
+	balance_callback(rq);
+	preempt_enable();
+
+	if (current->set_child_tid)
+		put_user(task_pid_vnr(current), current->set_child_tid);
+
+	calculate_sigpending();
+}
+
+/*
+ * context_switch - switch to the new MM and the new thread's register state.
+ */
+static __always_inline struct rq *
+context_switch(struct rq *rq, struct task_struct *prev,
+	       struct task_struct *next, struct rq_flags *rf)
+{
+	struct mm_struct *mm, *oldmm;
+
+	prepare_task_switch(rq, prev, next);
+
+	mm = next->mm;
+	oldmm = prev->active_mm;
+	/*
+	 * For paravirt, this is coupled with an exit in switch_to to
+	 * combine the page table reload and the switch backend into
+	 * one hypercall.
+	 */
+	arch_start_context_switch(prev);
+
+	/*
+	 * If mm is non-NULL, we pass through switch_mm(). If mm is
+	 * NULL, we will pass through mmdrop() in finish_task_switch().
+	 * Both of these contain the full memory barrier required by
+	 * membarrier after storing to rq->curr, before returning to
+	 * user-space.
+	 */
+	if (!mm) {
+		next->active_mm = oldmm;
+		mmgrab(oldmm);
+		enter_lazy_tlb(oldmm, next);
+	} else
+		switch_mm_irqs_off(oldmm, mm, next);
+
+	if (!prev->mm) {
+		prev->active_mm = NULL;
+		rq->prev_mm = oldmm;
+	}
+
+	rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
+
+	prepare_lock_switch(rq, next, rf);
+
+	/* Here we just switch the register state and the stack. */
+	switch_to(prev, next, prev);
+	barrier();
+
+	return finish_task_switch(prev);
+}
+
+/*
+ * nr_running and nr_context_switches:
+ *
+ * externally visible scheduler statistics: current number of runnable
+ * threads, total number of context switches performed since bootup.
+ */
+unsigned long nr_running(void)
+{
+	unsigned long i, sum = 0;
+
+	for_each_online_cpu(i)
+		sum += cpu_rq(i)->nr_running;
+
+	return sum;
+}
+
+/*
+ * Check if only the current task is running on the CPU.
+ *
+ * Caution: this function does not check that the caller has disabled
+ * preemption, thus the result might have a time-of-check-to-time-of-use
+ * race.  The caller is responsible to use it correctly, for example:
+ *
+ * - from a non-preemptable section (of course)
+ *
+ * - from a thread that is bound to a single CPU
+ *
+ * - in a loop with very short iterations (e.g. a polling loop)
+ */
+bool single_task_running(void)
+{
+	return raw_rq()->nr_running == 1;
+}
+EXPORT_SYMBOL(single_task_running);
+
+unsigned long long nr_context_switches(void)
+{
+	int i;
+	unsigned long long sum = 0;
+
+	for_each_possible_cpu(i)
+		sum += cpu_rq(i)->nr_switches;
+
+	return sum;
+}
+
+/*
+ * IO-wait accounting, and how its mostly bollocks (on SMP).
+ *
+ * The idea behind IO-wait account is to account the idle time that we could
+ * have spend running if it were not for IO. That is, if we were to improve the
+ * storage performance, we'd have a proportional reduction in IO-wait time.
+ *
+ * This all works nicely on UP, where, when a task blocks on IO, we account
+ * idle time as IO-wait, because if the storage were faster, it could've been
+ * running and we'd not be idle.
+ *
+ * This has been extended to SMP, by doing the same for each CPU. This however
+ * is broken.
+ *
+ * Imagine for instance the case where two tasks block on one CPU, only the one
+ * CPU will have IO-wait accounted, while the other has regular idle. Even
+ * though, if the storage were faster, both could've ran at the same time,
+ * utilising both CPUs.
+ *
+ * This means, that when looking globally, the current IO-wait accounting on
+ * SMP is a lower bound, by reason of under accounting.
+ *
+ * Worse, since the numbers are provided per CPU, they are sometimes
+ * interpreted per CPU, and that is nonsensical. A blocked task isn't strictly
+ * associated with any one particular CPU, it can wake to another CPU than it
+ * blocked on. This means the per CPU IO-wait number is meaningless.
+ *
+ * Task CPU affinities can make all that even more 'interesting'.
+ */
+
+unsigned long nr_iowait(void)
+{
+	unsigned long i, sum = 0;
+
+	for_each_possible_cpu(i)
+		sum += atomic_read(&cpu_rq(i)->nr_iowait);
+
+	return sum;
+}
+
+/*
+ * Consumers of these two interfaces, like for example the cpufreq menu
+ * governor are using nonsensical data. Boosting frequency for a CPU that has
+ * IO-wait which might not even end up running the task when it does become
+ * runnable.
+ */
+
+unsigned long nr_iowait_cpu(int cpu)
+{
+	struct rq *this = cpu_rq(cpu);
+	return atomic_read(&this->nr_iowait);
+}
+
+void get_iowait_load(unsigned long *nr_waiters, unsigned long *load)
+{
+	struct rq *rq = this_rq();
+	*nr_waiters = atomic_read(&rq->nr_iowait);
+	*load = rq->load.weight;
+}
+
+#ifdef CONFIG_SMP
+
+/*
+ * sched_exec - execve() is a valuable balancing opportunity, because at
+ * this point the task has the smallest effective memory and cache footprint.
+ */
+void sched_exec(void)
+{
+	struct task_struct *p = current;
+	unsigned long flags;
+	int dest_cpu;
+
+	raw_spin_lock_irqsave(&p->pi_lock, flags);
+	dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), SD_BALANCE_EXEC, 0);
+	if (dest_cpu == smp_processor_id())
+		goto unlock;
+
+	if (likely(cpu_active(dest_cpu))) {
+		struct migration_arg arg = { p, dest_cpu };
+
+		raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+		stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
+		return;
+	}
+unlock:
+	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+}
+
+#endif
+
+DEFINE_PER_CPU(struct kernel_stat, kstat);
+DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
+
+EXPORT_PER_CPU_SYMBOL(kstat);
+EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
+
+/*
+ * The function fair_sched_class.update_curr accesses the struct curr
+ * and its field curr->exec_start; when called from task_sched_runtime(),
+ * we observe a high rate of cache misses in practice.
+ * Prefetching this data results in improved performance.
+ */
+static inline void prefetch_curr_exec_start(struct task_struct *p)
+{
+#ifdef CONFIG_FAIR_GROUP_SCHED
+	struct sched_entity *curr = (&p->se)->cfs_rq->curr;
+#else
+	struct sched_entity *curr = (&task_rq(p)->cfs)->curr;
+#endif
+	prefetch(curr);
+	prefetch(&curr->exec_start);
+}
+
+/*
+ * Return accounted runtime for the task.
+ * In case the task is currently running, return the runtime plus current's
+ * pending runtime that have not been accounted yet.
+ */
+unsigned long long task_sched_runtime(struct task_struct *p)
+{
+	struct rq_flags rf;
+	struct rq *rq;
+	u64 ns;
+
+#if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
+	/*
+	 * 64-bit doesn't need locks to atomically read a 64-bit value.
+	 * So we have a optimization chance when the task's delta_exec is 0.
+	 * Reading ->on_cpu is racy, but this is ok.
+	 *
+	 * 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 || !task_on_rq_queued(p))
+		return p->se.sum_exec_runtime;
+#endif
+
+	rq = task_rq_lock(p, &rf);
+	/*
+	 * 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) && task_on_rq_queued(p)) {
+		prefetch_curr_exec_start(p);
+		update_rq_clock(rq);
+		p->sched_class->update_curr(rq);
+	}
+	ns = p->se.sum_exec_runtime;
+	task_rq_unlock(rq, p, &rf);
+
+	return ns;
+}
+
+/*
+ * This function gets called by the timer code, with HZ frequency.
+ * We call it with interrupts disabled.
+ */
+void scheduler_tick(void)
+{
+	int cpu = smp_processor_id();
+	struct rq *rq = cpu_rq(cpu);
+	struct task_struct *curr = rq->curr;
+	struct rq_flags rf;
+
+	sched_clock_tick();
+
+	rq_lock(rq, &rf);
+
+	update_rq_clock(rq);
+	curr->sched_class->task_tick(rq, curr, 0);
+	cpu_load_update_active(rq);
+	calc_global_load_tick(rq);
+
+	rq_unlock(rq, &rf);
+
+	perf_event_task_tick();
+
+#ifdef CONFIG_SMP
+	rq->idle_balance = idle_cpu(cpu);
+	trigger_load_balance(rq);
+#endif
+}
+
+#ifdef CONFIG_NO_HZ_FULL
+
+struct tick_work {
+	int			cpu;
+	atomic_t		state;
+	struct delayed_work	work;
+};
+/* Values for ->state, see diagram below. */
+#define TICK_SCHED_REMOTE_OFFLINE	0
+#define TICK_SCHED_REMOTE_OFFLINING	1
+#define TICK_SCHED_REMOTE_RUNNING	2
+
+/*
+ * State diagram for ->state:
+ *
+ *
+ *          TICK_SCHED_REMOTE_OFFLINE
+ *                    |   ^
+ *                    |   |
+ *                    |   | sched_tick_remote()
+ *                    |   |
+ *                    |   |
+ *                    +--TICK_SCHED_REMOTE_OFFLINING
+ *                    |   ^
+ *                    |   |
+ * sched_tick_start() |   | sched_tick_stop()
+ *                    |   |
+ *                    V   |
+ *          TICK_SCHED_REMOTE_RUNNING
+ *
+ *
+ * Other transitions get WARN_ON_ONCE(), except that sched_tick_remote()
+ * and sched_tick_start() are happy to leave the state in RUNNING.
+ */
+
+static struct tick_work __percpu *tick_work_cpu;
+
+static void sched_tick_remote(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct tick_work *twork = container_of(dwork, struct tick_work, work);
+	int cpu = twork->cpu;
+	struct rq *rq = cpu_rq(cpu);
+	struct task_struct *curr;
+	struct rq_flags rf;
+	u64 delta;
+	int os;
+
+	/*
+	 * Handle the tick only if it appears the remote CPU is running in full
+	 * dynticks mode. The check is racy by nature, but missing a tick or
+	 * having one too much is no big deal because the scheduler tick updates
+	 * statistics and checks timeslices in a time-independent way, regardless
+	 * of when exactly it is running.
+	 */
+	if (idle_cpu(cpu) || !tick_nohz_tick_stopped_cpu(cpu))
+		goto out_requeue;
+
+	rq_lock_irq(rq, &rf);
+	curr = rq->curr;
+	if (is_idle_task(curr) || cpu_is_offline(cpu))
+		goto out_unlock;
+
+	update_rq_clock(rq);
+	delta = rq_clock_task(rq) - curr->se.exec_start;
+
+	/*
+	 * Make sure the next tick runs within a reasonable
+	 * amount of time.
+	 */
+	WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
+	curr->sched_class->task_tick(rq, curr, 0);
+
+out_unlock:
+	rq_unlock_irq(rq, &rf);
+
+out_requeue:
+	/*
+	 * Run the remote tick once per second (1Hz). This arbitrary
+	 * frequency is large enough to avoid overload but short enough
+	 * to keep scheduler internal stats reasonably up to date.  But
+	 * first update state to reflect hotplug activity if required.
+	 */
+	os = atomic_fetch_add_unless(&twork->state, -1, TICK_SCHED_REMOTE_RUNNING);
+	WARN_ON_ONCE(os == TICK_SCHED_REMOTE_OFFLINE);
+	if (os == TICK_SCHED_REMOTE_RUNNING)
+		queue_delayed_work(system_unbound_wq, dwork, HZ);
+}
+
+static void sched_tick_start(int cpu)
+{
+	int os;
+	struct tick_work *twork;
+
+	if (housekeeping_cpu(cpu, HK_FLAG_TICK))
+		return;
+
+	WARN_ON_ONCE(!tick_work_cpu);
+
+	twork = per_cpu_ptr(tick_work_cpu, cpu);
+	os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_RUNNING);
+	WARN_ON_ONCE(os == TICK_SCHED_REMOTE_RUNNING);
+	if (os == TICK_SCHED_REMOTE_OFFLINE) {
+		twork->cpu = cpu;
+		INIT_DELAYED_WORK(&twork->work, sched_tick_remote);
+		queue_delayed_work(system_unbound_wq, &twork->work, HZ);
+	}
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void sched_tick_stop(int cpu)
+{
+	struct tick_work *twork;
+	int os;
+
+	if (housekeeping_cpu(cpu, HK_FLAG_TICK))
+		return;
+
+	WARN_ON_ONCE(!tick_work_cpu);
+
+	twork = per_cpu_ptr(tick_work_cpu, cpu);
+	/* There cannot be competing actions, but don't rely on stop-machine. */
+	os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_OFFLINING);
+	WARN_ON_ONCE(os != TICK_SCHED_REMOTE_RUNNING);
+	/* Don't cancel, as this would mess up the state machine. */
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+int __init sched_tick_offload_init(void)
+{
+	tick_work_cpu = alloc_percpu(struct tick_work);
+	BUG_ON(!tick_work_cpu);
+	return 0;
+}
+
+#else /* !CONFIG_NO_HZ_FULL */
+static inline void sched_tick_start(int cpu) { }
+static inline void sched_tick_stop(int cpu) { }
+#endif
+
+#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
+				defined(CONFIG_TRACE_PREEMPT_TOGGLE))
+/*
+ * If the value passed in is equal to the current preempt count
+ * then we just disabled preemption. Start timing the latency.
+ */
+static inline void preempt_latency_start(int val)
+{
+	if (preempt_count() == val) {
+		unsigned long ip = get_lock_parent_ip();
+#ifdef CONFIG_DEBUG_PREEMPT
+		current->preempt_disable_ip = ip;
+#endif
+		trace_preempt_off(CALLER_ADDR0, ip);
+	}
+}
+
+void preempt_count_add(int val)
+{
+#ifdef CONFIG_DEBUG_PREEMPT
+	/*
+	 * Underflow?
+	 */
+	if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
+		return;
+#endif
+	__preempt_count_add(val);
+#ifdef CONFIG_DEBUG_PREEMPT
+	/*
+	 * Spinlock count overflowing soon?
+	 */
+	DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
+				PREEMPT_MASK - 10);
+#endif
+	preempt_latency_start(val);
+}
+EXPORT_SYMBOL(preempt_count_add);
+NOKPROBE_SYMBOL(preempt_count_add);
+
+/*
+ * If the value passed in equals to the current preempt count
+ * then we just enabled preemption. Stop timing the latency.
+ */
+static inline void preempt_latency_stop(int val)
+{
+	if (preempt_count() == val)
+		trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
+}
+
+void preempt_count_sub(int val)
+{
+#ifdef CONFIG_DEBUG_PREEMPT
+	/*
+	 * Underflow?
+	 */
+	if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
+		return;
+	/*
+	 * Is the spinlock portion underflowing?
+	 */
+	if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
+			!(preempt_count() & PREEMPT_MASK)))
+		return;
+#endif
+
+	preempt_latency_stop(val);
+	__preempt_count_sub(val);
+}
+EXPORT_SYMBOL(preempt_count_sub);
+NOKPROBE_SYMBOL(preempt_count_sub);
+
+#else
+static inline void preempt_latency_start(int val) { }
+static inline void preempt_latency_stop(int val) { }
+#endif
+
+static inline unsigned long get_preempt_disable_ip(struct task_struct *p)
+{
+#ifdef CONFIG_DEBUG_PREEMPT
+	return p->preempt_disable_ip;
+#else
+	return 0;
+#endif
+}
+
+/*
+ * Print scheduling while atomic bug:
+ */
+static noinline void __schedule_bug(struct task_struct *prev)
+{
+	/* Save this before calling printk(), since that will clobber it */
+	unsigned long preempt_disable_ip = get_preempt_disable_ip(current);
+
+	if (oops_in_progress)
+		return;
+
+	printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
+		prev->comm, prev->pid, preempt_count());
+
+	debug_show_held_locks(prev);
+	print_modules();
+	if (irqs_disabled())
+		print_irqtrace_events(prev);
+	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
+	    && in_atomic_preempt_off()) {
+		pr_err("Preemption disabled at:");
+		print_ip_sym(preempt_disable_ip);
+		pr_cont("\n");
+	}
+	if (panic_on_warn)
+		panic("scheduling while atomic\n");
+
+	dump_stack();
+	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
+}
+
+/*
+ * Various schedule()-time debugging checks and statistics:
+ */
+static inline void schedule_debug(struct task_struct *prev)
+{
+#ifdef CONFIG_SCHED_STACK_END_CHECK
+	if (task_stack_end_corrupted(prev))
+		panic("corrupted stack end detected inside scheduler\n");
+#endif
+
+	if (unlikely(in_atomic_preempt_off())) {
+		__schedule_bug(prev);
+		preempt_count_set(PREEMPT_DISABLED);
+	}
+	rcu_sleep_check();
+
+	profile_hit(SCHED_PROFILING, __builtin_return_address(0));
+
+	schedstat_inc(this_rq()->sched_count);
+}
+
+/*
+ * Pick up the highest-prio task:
+ */
+static inline struct task_struct *
+pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+{
+	const struct sched_class *class;
+	struct task_struct *p;
+
+	/*
+	 * Optimization: we know that if all tasks are in the fair class we can
+	 * call that function directly, but only if the @prev task wasn't of a
+	 * higher scheduling class, because otherwise those loose the
+	 * opportunity to pull in more work from other CPUs.
+	 */
+	if (likely((prev->sched_class == &idle_sched_class ||
+		    prev->sched_class == &fair_sched_class) &&
+		   rq->nr_running == rq->cfs.h_nr_running)) {
+
+		p = fair_sched_class.pick_next_task(rq, prev, rf);
+		if (unlikely(p == RETRY_TASK))
+			goto again;
+
+		/* Assumes fair_sched_class->next == idle_sched_class */
+		if (unlikely(!p))
+			p = idle_sched_class.pick_next_task(rq, prev, rf);
+
+		return p;
+	}
+
+again:
+	for_each_class(class) {
+		p = class->pick_next_task(rq, prev, rf);
+		if (p) {
+			if (unlikely(p == RETRY_TASK))
+				goto again;
+			return p;
+		}
+	}
+
+	/* The idle class should always have a runnable task: */
+	BUG();
+}
+
+/*
+ * __schedule() is the main scheduler function.
+ *
+ * The main means of driving the scheduler and thus entering this function are:
+ *
+ *   1. Explicit blocking: mutex, semaphore, waitqueue, etc.
+ *
+ *   2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
+ *      paths. For example, see arch/x86/entry_64.S.
+ *
+ *      To drive preemption between tasks, the scheduler sets the flag in timer
+ *      interrupt handler scheduler_tick().
+ *
+ *   3. Wakeups don't really cause entry into schedule(). They add a
+ *      task to the run-queue and that's it.
+ *
+ *      Now, if the new task added to the run-queue preempts the current
+ *      task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
+ *      called on the nearest possible occasion:
+ *
+ *       - If the kernel is preemptible (CONFIG_PREEMPT=y):
+ *
+ *         - in syscall or exception context, at the next outmost
+ *           preempt_enable(). (this might be as soon as the wake_up()'s
+ *           spin_unlock()!)
+ *
+ *         - in IRQ context, return from interrupt-handler to
+ *           preemptible context
+ *
+ *       - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
+ *         then at the next:
+ *
+ *          - cond_resched() call
+ *          - explicit schedule() call
+ *          - return from syscall or exception to user-space
+ *          - return from interrupt-handler to user-space
+ *
+ * WARNING: must be called with preemption disabled!
+ */
+static void __sched notrace __schedule(bool preempt)
+{
+	struct task_struct *prev, *next;
+	unsigned long *switch_count;
+	struct rq_flags rf;
+	struct rq *rq;
+	int cpu;
+
+	cpu = smp_processor_id();
+	rq = cpu_rq(cpu);
+	prev = rq->curr;
+
+	schedule_debug(prev);
+
+	if (sched_feat(HRTICK))
+		hrtick_clear(rq);
+
+	local_irq_disable();
+	rcu_note_context_switch(preempt);
+
+	/*
+	 * Make sure that signal_pending_state()->signal_pending() below
+	 * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
+	 * done by the caller to avoid the race with signal_wake_up().
+	 *
+	 * The membarrier system call requires a full memory barrier
+	 * after coming from user-space, before storing to rq->curr.
+	 */
+	rq_lock(rq, &rf);
+	smp_mb__after_spinlock();
+
+	/* Promote REQ to ACT */
+	rq->clock_update_flags <<= 1;
+	update_rq_clock(rq);
+
+	switch_count = &prev->nivcsw;
+	if (!preempt && prev->state) {
+		if (unlikely(signal_pending_state(prev->state, prev))) {
+			prev->state = TASK_RUNNING;
+		} else {
+			deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK);
+			prev->on_rq = 0;
+
+			if (prev->in_iowait) {
+				atomic_inc(&rq->nr_iowait);
+				delayacct_blkio_start();
+			}
+
+			/*
+			 * If a worker went to sleep, notify and ask workqueue
+			 * whether it wants to wake up a task to maintain
+			 * concurrency.
+			 */
+			if (prev->flags & PF_WQ_WORKER) {
+				struct task_struct *to_wakeup;
+
+				to_wakeup = wq_worker_sleeping(prev);
+				if (to_wakeup)
+					try_to_wake_up_local(to_wakeup, &rf);
+			}
+		}
+		switch_count = &prev->nvcsw;
+	}
+
+	next = pick_next_task(rq, prev, &rf);
+	clear_tsk_need_resched(prev);
+	clear_preempt_need_resched();
+
+	if (likely(prev != next)) {
+		rq->nr_switches++;
+		rq->curr = next;
+		/*
+		 * The membarrier system call requires each architecture
+		 * to have a full memory barrier after updating
+		 * rq->curr, before returning to user-space.
+		 *
+		 * Here are the schemes providing that barrier on the
+		 * various architectures:
+		 * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC.
+		 *   switch_mm() rely on membarrier_arch_switch_mm() on PowerPC.
+		 * - finish_lock_switch() for weakly-ordered
+		 *   architectures where spin_unlock is a full barrier,
+		 * - switch_to() for arm64 (weakly-ordered, spin_unlock
+		 *   is a RELEASE barrier),
+		 */
+		++*switch_count;
+
+		trace_sched_switch(preempt, prev, next);
+
+		/* Also unlocks the rq: */
+		rq = context_switch(rq, prev, next, &rf);
+	} else {
+		rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
+		rq_unlock_irq(rq, &rf);
+	}
+
+	balance_callback(rq);
+}
+
+void __noreturn do_task_dead(void)
+{
+	/* Causes final put_task_struct in finish_task_switch(): */
+	set_special_state(TASK_DEAD);
+
+	/* Tell freezer to ignore us: */
+	current->flags |= PF_NOFREEZE;
+
+	__schedule(false);
+	BUG();
+
+	/* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */
+	for (;;)
+		cpu_relax();
+}
+
+static inline void sched_submit_work(struct task_struct *tsk)
+{
+	if (!tsk->state || tsk_is_pi_blocked(tsk))
+		return;
+	/*
+	 * If we are going to sleep and we have plugged IO queued,
+	 * make sure to submit it to avoid deadlocks.
+	 */
+	if (blk_needs_flush_plug(tsk))
+		blk_schedule_flush_plug(tsk);
+}
+
+asmlinkage __visible void __sched schedule(void)
+{
+	struct task_struct *tsk = current;
+
+	sched_submit_work(tsk);
+	do {
+		preempt_disable();
+		__schedule(false);
+		sched_preempt_enable_no_resched();
+	} while (need_resched());
+}
+EXPORT_SYMBOL(schedule);
+
+/*
+ * synchronize_rcu_tasks() makes sure that no task is stuck in preempted
+ * state (have scheduled out non-voluntarily) by making sure that all
+ * tasks have either left the run queue or have gone into user space.
+ * As idle tasks do not do either, they must not ever be preempted
+ * (schedule out non-voluntarily).
+ *
+ * schedule_idle() is similar to schedule_preempt_disable() except that it
+ * never enables preemption because it does not call sched_submit_work().
+ */
+void __sched schedule_idle(void)
+{
+	/*
+	 * As this skips calling sched_submit_work(), which the idle task does
+	 * regardless because that function is a nop when the task is in a
+	 * TASK_RUNNING state, make sure this isn't used someplace that the
+	 * current task can be in any other state. Note, idle is always in the
+	 * TASK_RUNNING state.
+	 */
+	WARN_ON_ONCE(current->state);
+	do {
+		__schedule(false);
+	} while (need_resched());
+}
+
+#ifdef CONFIG_CONTEXT_TRACKING
+asmlinkage __visible void __sched schedule_user(void)
+{
+	/*
+	 * If we come here after a random call to set_need_resched(),
+	 * or we have been woken up remotely but the IPI has not yet arrived,
+	 * we haven't yet exited the RCU idle mode. Do it here manually until
+	 * we find a better solution.
+	 *
+	 * NB: There are buggy callers of this function.  Ideally we
+	 * should warn if prev_state != CONTEXT_USER, but that will trigger
+	 * too frequently to make sense yet.
+	 */
+	enum ctx_state prev_state = exception_enter();
+	schedule();
+	exception_exit(prev_state);
+}
+#endif
+
+/**
+ * schedule_preempt_disabled - called with preemption disabled
+ *
+ * Returns with preemption disabled. Note: preempt_count must be 1
+ */
+void __sched schedule_preempt_disabled(void)
+{
+	sched_preempt_enable_no_resched();
+	schedule();
+	preempt_disable();
+}
+
+static void __sched notrace preempt_schedule_common(void)
+{
+	do {
+		/*
+		 * Because the function tracer can trace preempt_count_sub()
+		 * and it also uses preempt_enable/disable_notrace(), if
+		 * NEED_RESCHED is set, the preempt_enable_notrace() called
+		 * by the function tracer will call this function again and
+		 * cause infinite recursion.
+		 *
+		 * Preemption must be disabled here before the function
+		 * tracer can trace. Break up preempt_disable() into two
+		 * calls. One to disable preemption without fear of being
+		 * traced. The other to still record the preemption latency,
+		 * which can also be traced by the function tracer.
+		 */
+		preempt_disable_notrace();
+		preempt_latency_start(1);
+		__schedule(true);
+		preempt_latency_stop(1);
+		preempt_enable_no_resched_notrace();
+
+		/*
+		 * Check again in case we missed a preemption opportunity
+		 * between schedule and now.
+		 */
+	} while (need_resched());
+}
+
+#ifdef CONFIG_PREEMPT
+/*
+ * this is the entry point to schedule() from in-kernel preemption
+ * off of preempt_enable. Kernel preemptions off return from interrupt
+ * occur there and call schedule directly.
+ */
+asmlinkage __visible void __sched notrace preempt_schedule(void)
+{
+	/*
+	 * If there is a non-zero preempt_count or interrupts are disabled,
+	 * we do not want to preempt the current task. Just return..
+	 */
+	if (likely(!preemptible()))
+		return;
+
+	preempt_schedule_common();
+}
+NOKPROBE_SYMBOL(preempt_schedule);
+EXPORT_SYMBOL(preempt_schedule);
+
+/**
+ * preempt_schedule_notrace - preempt_schedule called by tracing
+ *
+ * The tracing infrastructure uses preempt_enable_notrace to prevent
+ * recursion and tracing preempt enabling caused by the tracing
+ * infrastructure itself. But as tracing can happen in areas coming
+ * from userspace or just about to enter userspace, a preempt enable
+ * can occur before user_exit() is called. This will cause the scheduler
+ * to be called when the system is still in usermode.
+ *
+ * To prevent this, the preempt_enable_notrace will use this function
+ * instead of preempt_schedule() to exit user context if needed before
+ * calling the scheduler.
+ */
+asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
+{
+	enum ctx_state prev_ctx;
+
+	if (likely(!preemptible()))
+		return;
+
+	do {
+		/*
+		 * Because the function tracer can trace preempt_count_sub()
+		 * and it also uses preempt_enable/disable_notrace(), if
+		 * NEED_RESCHED is set, the preempt_enable_notrace() called
+		 * by the function tracer will call this function again and
+		 * cause infinite recursion.
+		 *
+		 * Preemption must be disabled here before the function
+		 * tracer can trace. Break up preempt_disable() into two
+		 * calls. One to disable preemption without fear of being
+		 * traced. The other to still record the preemption latency,
+		 * which can also be traced by the function tracer.
+		 */
+		preempt_disable_notrace();
+		preempt_latency_start(1);
+		/*
+		 * Needs preempt disabled in case user_exit() is traced
+		 * and the tracer calls preempt_enable_notrace() causing
+		 * an infinite recursion.
+		 */
+		prev_ctx = exception_enter();
+		__schedule(true);
+		exception_exit(prev_ctx);
+
+		preempt_latency_stop(1);
+		preempt_enable_no_resched_notrace();
+	} while (need_resched());
+}
+EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
+
+#endif /* CONFIG_PREEMPT */
+
+/*
+ * this is the entry point to schedule() from kernel preemption
+ * off of irq context.
+ * Note, that this is called and return with irqs disabled. This will
+ * protect us against recursive calling from irq.
+ */
+asmlinkage __visible void __sched preempt_schedule_irq(void)
+{
+	enum ctx_state prev_state;
+
+	/* Catch callers which need to be fixed */
+	BUG_ON(preempt_count() || !irqs_disabled());
+
+	prev_state = exception_enter();
+
+	do {
+		preempt_disable();
+		local_irq_enable();
+		__schedule(true);
+		local_irq_disable();
+		sched_preempt_enable_no_resched();
+	} while (need_resched());
+
+	exception_exit(prev_state);
+}
+
+int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags,
+			  void *key)
+{
+	return try_to_wake_up(curr->private, mode, wake_flags);
+}
+EXPORT_SYMBOL(default_wake_function);
+
+#ifdef CONFIG_RT_MUTEXES
+
+static inline int __rt_effective_prio(struct task_struct *pi_task, int prio)
+{
+	if (pi_task)
+		prio = min(prio, pi_task->prio);
+
+	return prio;
+}
+
+static inline int rt_effective_prio(struct task_struct *p, int prio)
+{
+	struct task_struct *pi_task = rt_mutex_get_top_task(p);
+
+	return __rt_effective_prio(pi_task, prio);
+}
+
+/*
+ * rt_mutex_setprio - set the current priority of a task
+ * @p: task to boost
+ * @pi_task: donor task
+ *
+ * This function changes the 'effective' priority of a task. It does
+ * not touch ->normal_prio like __setscheduler().
+ *
+ * Used by the rt_mutex code to implement priority inheritance
+ * logic. Call site only calls if the priority of the task changed.
+ */
+void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
+{
+	int prio, oldprio, queued, running, queue_flag =
+		DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
+	const struct sched_class *prev_class;
+	struct rq_flags rf;
+	struct rq *rq;
+
+	/* XXX used to be waiter->prio, not waiter->task->prio */
+	prio = __rt_effective_prio(pi_task, p->normal_prio);
+
+	/*
+	 * If nothing changed; bail early.
+	 */
+	if (p->pi_top_task == pi_task && prio == p->prio && !dl_prio(prio))
+		return;
+
+	rq = __task_rq_lock(p, &rf);
+	update_rq_clock(rq);
+	/*
+	 * Set under pi_lock && rq->lock, such that the value can be used under
+	 * either lock.
+	 *
+	 * Note that there is loads of tricky to make this pointer cache work
+	 * right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to
+	 * ensure a task is de-boosted (pi_task is set to NULL) before the
+	 * task is allowed to run again (and can exit). This ensures the pointer
+	 * points to a blocked task -- which guaratees the task is present.
+	 */
+	p->pi_top_task = pi_task;
+
+	/*
+	 * For FIFO/RR we only need to set prio, if that matches we're done.
+	 */
+	if (prio == p->prio && !dl_prio(prio))
+		goto out_unlock;
+
+	/*
+	 * Idle task boosting is a nono in general. There is one
+	 * exception, when PREEMPT_RT and NOHZ is active:
+	 *
+	 * The idle task calls get_next_timer_interrupt() and holds
+	 * the timer wheel base->lock on the CPU and another CPU wants
+	 * to access the timer (probably to cancel it). We can safely
+	 * ignore the boosting request, as the idle CPU runs this code
+	 * with interrupts disabled and will complete the lock
+	 * protected section without being interrupted. So there is no
+	 * real need to boost.
+	 */
+	if (unlikely(p == rq->idle)) {
+		WARN_ON(p != rq->curr);
+		WARN_ON(p->pi_blocked_on);
+		goto out_unlock;
+	}
+
+	trace_sched_pi_setprio(p, pi_task);
+	oldprio = p->prio;
+
+	if (oldprio == prio)
+		queue_flag &= ~DEQUEUE_MOVE;
+
+	prev_class = p->sched_class;
+	queued = task_on_rq_queued(p);
+	running = task_current(rq, p);
+	if (queued)
+		dequeue_task(rq, p, queue_flag);
+	if (running)
+		put_prev_task(rq, p);
+
+	/*
+	 * Boosting condition are:
+	 * 1. -rt task is running and holds mutex A
+	 *      --> -dl task blocks on mutex A
+	 *
+	 * 2. -dl task is running and holds mutex A
+	 *      --> -dl task blocks on mutex A and could preempt the
+	 *          running task
+	 */
+	if (dl_prio(prio)) {
+		if (!dl_prio(p->normal_prio) ||
+		    (pi_task && dl_prio(pi_task->prio) &&
+		     dl_entity_preempt(&pi_task->dl, &p->dl))) {
+			p->dl.dl_boosted = 1;
+			queue_flag |= ENQUEUE_REPLENISH;
+		} else
+			p->dl.dl_boosted = 0;
+		p->sched_class = &dl_sched_class;
+	} else if (rt_prio(prio)) {
+		if (dl_prio(oldprio))
+			p->dl.dl_boosted = 0;
+		if (oldprio < prio)
+			queue_flag |= ENQUEUE_HEAD;
+		p->sched_class = &rt_sched_class;
+	} else {
+		if (dl_prio(oldprio))
+			p->dl.dl_boosted = 0;
+		if (rt_prio(oldprio))
+			p->rt.timeout = 0;
+		p->sched_class = &fair_sched_class;
+	}
+
+	p->prio = prio;
+
+	if (queued)
+		enqueue_task(rq, p, queue_flag);
+	if (running)
+		set_curr_task(rq, p);
+
+	check_class_changed(rq, p, prev_class, oldprio);
+out_unlock:
+	/* Avoid rq from going away on us: */
+	preempt_disable();
+	__task_rq_unlock(rq, &rf);
+
+	balance_callback(rq);
+	preempt_enable();
+}
+#else
+static inline int rt_effective_prio(struct task_struct *p, int prio)
+{
+	return prio;
+}
+#endif
+
+void set_user_nice(struct task_struct *p, long nice)
+{
+	bool queued, running;
+	int old_prio, delta;
+	struct rq_flags rf;
+	struct rq *rq;
+
+	if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
+		return;
+	/*
+	 * We have to be careful, if called from sys_setpriority(),
+	 * the task might be in the middle of scheduling on another CPU.
+	 */
+	rq = task_rq_lock(p, &rf);
+	update_rq_clock(rq);
+
+	/*
+	 * The RT priorities are set via sched_setscheduler(), but we still
+	 * allow the 'normal' nice value to be set - but as expected
+	 * it wont have any effect on scheduling until the task is
+	 * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
+	 */
+	if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
+		p->static_prio = NICE_TO_PRIO(nice);
+		goto out_unlock;
+	}
+	queued = task_on_rq_queued(p);
+	running = task_current(rq, p);
+	if (queued)
+		dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
+	if (running)
+		put_prev_task(rq, p);
+
+	p->static_prio = NICE_TO_PRIO(nice);
+	set_load_weight(p, true);
+	old_prio = p->prio;
+	p->prio = effective_prio(p);
+	delta = p->prio - old_prio;
+
+	if (queued) {
+		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
+		/*
+		 * If the task increased its priority or is running and
+		 * lowered its priority, then reschedule its CPU:
+		 */
+		if (delta < 0 || (delta > 0 && task_running(rq, p)))
+			resched_curr(rq);
+	}
+	if (running)
+		set_curr_task(rq, p);
+out_unlock:
+	task_rq_unlock(rq, p, &rf);
+}
+EXPORT_SYMBOL(set_user_nice);
+
+/*
+ * can_nice - check if a task can reduce its nice value
+ * @p: task
+ * @nice: nice value
+ */
+int can_nice(const struct task_struct *p, const int nice)
+{
+	/* Convert nice value [19,-20] to rlimit style value [1,40]: */
+	int nice_rlim = nice_to_rlimit(nice);
+
+	return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
+		capable(CAP_SYS_NICE));
+}
+
+#ifdef __ARCH_WANT_SYS_NICE
+
+/*
+ * sys_nice - change the priority of the current process.
+ * @increment: priority increment
+ *
+ * sys_setpriority is a more generic, but much slower function that
+ * does similar things.
+ */
+SYSCALL_DEFINE1(nice, int, increment)
+{
+	long nice, retval;
+
+	/*
+	 * Setpriority might change our priority at the same moment.
+	 * We don't have to worry. Conceptually one call occurs first
+	 * and we have a single winner.
+	 */
+	increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
+	nice = task_nice(current) + increment;
+
+	nice = clamp_val(nice, MIN_NICE, MAX_NICE);
+	if (increment < 0 && !can_nice(current, nice))
+		return -EPERM;
+
+	retval = security_task_setnice(current, nice);
+	if (retval)
+		return retval;
+
+	set_user_nice(current, nice);
+	return 0;
+}
+
+#endif
+
+/**
+ * task_prio - return the priority value of a given task.
+ * @p: the task in question.
+ *
+ * Return: The priority value as seen by users in /proc.
+ * RT tasks are offset by -200. Normal tasks are centered
+ * around 0, value goes from -16 to +15.
+ */
+int task_prio(const struct task_struct *p)
+{
+	return p->prio - MAX_RT_PRIO;
+}
+
+/**
+ * idle_cpu - is a given CPU idle currently?
+ * @cpu: the processor in question.
+ *
+ * Return: 1 if the CPU is currently idle. 0 otherwise.
+ */
+int idle_cpu(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+
+	if (rq->curr != rq->idle)
+		return 0;
+
+	if (rq->nr_running)
+		return 0;
+
+#ifdef CONFIG_SMP
+	if (!llist_empty(&rq->wake_list))
+		return 0;
+#endif
+
+	return 1;
+}
+
+/**
+ * available_idle_cpu - is a given CPU idle for enqueuing work.
+ * @cpu: the CPU in question.
+ *
+ * Return: 1 if the CPU is currently idle. 0 otherwise.
+ */
+int available_idle_cpu(int cpu)
+{
+	if (!idle_cpu(cpu))
+		return 0;
+
+	if (vcpu_is_preempted(cpu))
+		return 0;
+
+	return 1;
+}
+
+/**
+ * idle_task - return the idle task for a given CPU.
+ * @cpu: the processor in question.
+ *
+ * Return: The idle task for the CPU @cpu.
+ */
+struct task_struct *idle_task(int cpu)
+{
+	return cpu_rq(cpu)->idle;
+}
+
+/**
+ * find_process_by_pid - find a process with a matching PID value.
+ * @pid: the pid in question.
+ *
+ * The task of @pid, if found. %NULL otherwise.
+ */
+static struct task_struct *find_process_by_pid(pid_t pid)
+{
+	return pid ? find_task_by_vpid(pid) : current;
+}
+
+/*
+ * sched_setparam() passes in -1 for its policy, to let the functions
+ * it calls know not to change it.
+ */
+#define SETPARAM_POLICY	-1
+
+static void __setscheduler_params(struct task_struct *p,
+		const struct sched_attr *attr)
+{
+	int policy = attr->sched_policy;
+
+	if (policy == SETPARAM_POLICY)
+		policy = p->policy;
+
+	p->policy = policy;
+
+	if (dl_policy(policy))
+		__setparam_dl(p, attr);
+	else if (fair_policy(policy))
+		p->static_prio = NICE_TO_PRIO(attr->sched_nice);
+
+	/*
+	 * __sched_setscheduler() ensures attr->sched_priority == 0 when
+	 * !rt_policy. Always setting this ensures that things like
+	 * getparam()/getattr() don't report silly values for !rt tasks.
+	 */
+	p->rt_priority = attr->sched_priority;
+	p->normal_prio = normal_prio(p);
+	set_load_weight(p, true);
+}
+
+/* Actually do priority change: must hold pi & rq lock. */
+static void __setscheduler(struct rq *rq, struct task_struct *p,
+			   const struct sched_attr *attr, bool keep_boost)
+{
+	__setscheduler_params(p, attr);
+
+	/*
+	 * Keep a potential priority boosting if called from
+	 * sched_setscheduler().
+	 */
+	p->prio = normal_prio(p);
+	if (keep_boost)
+		p->prio = rt_effective_prio(p, p->prio);
+
+	if (dl_prio(p->prio))
+		p->sched_class = &dl_sched_class;
+	else if (rt_prio(p->prio))
+		p->sched_class = &rt_sched_class;
+	else
+		p->sched_class = &fair_sched_class;
+}
+
+/*
+ * Check the target process has a UID that matches the current process's:
+ */
+static bool check_same_owner(struct task_struct *p)
+{
+	const struct cred *cred = current_cred(), *pcred;
+	bool match;
+
+	rcu_read_lock();
+	pcred = __task_cred(p);
+	match = (uid_eq(cred->euid, pcred->euid) ||
+		 uid_eq(cred->euid, pcred->uid));
+	rcu_read_unlock();
+	return match;
+}
+
+static int __sched_setscheduler(struct task_struct *p,
+				const struct sched_attr *attr,
+				bool user, bool pi)
+{
+	int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
+		      MAX_RT_PRIO - 1 - attr->sched_priority;
+	int retval, oldprio, oldpolicy = -1, queued, running;
+	int new_effective_prio, policy = attr->sched_policy;
+	const struct sched_class *prev_class;
+	struct rq_flags rf;
+	int reset_on_fork;
+	int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
+	struct rq *rq;
+
+	/* The pi code expects interrupts enabled */
+	BUG_ON(pi && in_interrupt());
+recheck:
+	/* Double check policy once rq lock held: */
+	if (policy < 0) {
+		reset_on_fork = p->sched_reset_on_fork;
+		policy = oldpolicy = p->policy;
+	} else {
+		reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
+
+		if (!valid_policy(policy))
+			return -EINVAL;
+	}
+
+	if (attr->sched_flags & ~(SCHED_FLAG_ALL | SCHED_FLAG_SUGOV))
+		return -EINVAL;
+
+	/*
+	 * Valid priorities for SCHED_FIFO and SCHED_RR are
+	 * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
+	 * SCHED_BATCH and SCHED_IDLE is 0.
+	 */
+	if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) ||
+	    (!p->mm && attr->sched_priority > MAX_RT_PRIO-1))
+		return -EINVAL;
+	if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
+	    (rt_policy(policy) != (attr->sched_priority != 0)))
+		return -EINVAL;
+
+	/*
+	 * Allow unprivileged RT tasks to decrease priority:
+	 */
+	if (user && !capable(CAP_SYS_NICE)) {
+		if (fair_policy(policy)) {
+			if (attr->sched_nice < task_nice(p) &&
+			    !can_nice(p, attr->sched_nice))
+				return -EPERM;
+		}
+
+		if (rt_policy(policy)) {
+			unsigned long rlim_rtprio =
+					task_rlimit(p, RLIMIT_RTPRIO);
+
+			/* Can't set/change the rt policy: */
+			if (policy != p->policy && !rlim_rtprio)
+				return -EPERM;
+
+			/* Can't increase priority: */
+			if (attr->sched_priority > p->rt_priority &&
+			    attr->sched_priority > rlim_rtprio)
+				return -EPERM;
+		}
+
+		 /*
+		  * Can't set/change SCHED_DEADLINE policy at all for now
+		  * (safest behavior); in the future we would like to allow
+		  * unprivileged DL tasks to increase their relative deadline
+		  * or reduce their runtime (both ways reducing utilization)
+		  */
+		if (dl_policy(policy))
+			return -EPERM;
+
+		/*
+		 * Treat SCHED_IDLE as nice 20. Only allow a switch to
+		 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
+		 */
+		if (idle_policy(p->policy) && !idle_policy(policy)) {
+			if (!can_nice(p, task_nice(p)))
+				return -EPERM;
+		}
+
+		/* Can't change other user's priorities: */
+		if (!check_same_owner(p))
+			return -EPERM;
+
+		/* Normal users shall not reset the sched_reset_on_fork flag: */
+		if (p->sched_reset_on_fork && !reset_on_fork)
+			return -EPERM;
+	}
+
+	if (user) {
+		if (attr->sched_flags & SCHED_FLAG_SUGOV)
+			return -EINVAL;
+
+		retval = security_task_setscheduler(p);
+		if (retval)
+			return retval;
+	}
+
+	/*
+	 * Make sure no PI-waiters arrive (or leave) while we are
+	 * changing the priority of the task:
+	 *
+	 * To be able to change p->policy safely, the appropriate
+	 * runqueue lock must be held.
+	 */
+	rq = task_rq_lock(p, &rf);
+	update_rq_clock(rq);
+
+	/*
+	 * Changing the policy of the stop threads its a very bad idea:
+	 */
+	if (p == rq->stop) {
+		task_rq_unlock(rq, p, &rf);
+		return -EINVAL;
+	}
+
+	/*
+	 * If not changing anything there's no need to proceed further,
+	 * but store a possible modification of reset_on_fork.
+	 */
+	if (unlikely(policy == p->policy)) {
+		if (fair_policy(policy) && attr->sched_nice != task_nice(p))
+			goto change;
+		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
+			goto change;
+		if (dl_policy(policy) && dl_param_changed(p, attr))
+			goto change;
+
+		p->sched_reset_on_fork = reset_on_fork;
+		task_rq_unlock(rq, p, &rf);
+		return 0;
+	}
+change:
+
+	if (user) {
+#ifdef CONFIG_RT_GROUP_SCHED
+		/*
+		 * Do not allow realtime tasks into groups that have no runtime
+		 * assigned.
+		 */
+		if (rt_bandwidth_enabled() && rt_policy(policy) &&
+				task_group(p)->rt_bandwidth.rt_runtime == 0 &&
+				!task_group_is_autogroup(task_group(p))) {
+			task_rq_unlock(rq, p, &rf);
+			return -EPERM;
+		}
+#endif
+#ifdef CONFIG_SMP
+		if (dl_bandwidth_enabled() && dl_policy(policy) &&
+				!(attr->sched_flags & SCHED_FLAG_SUGOV)) {
+			cpumask_t *span = rq->rd->span;
+
+			/*
+			 * Don't allow tasks with an affinity mask smaller than
+			 * the entire root_domain to become SCHED_DEADLINE. We
+			 * will also fail if there's no bandwidth available.
+			 */
+			if (!cpumask_subset(span, &p->cpus_allowed) ||
+			    rq->rd->dl_bw.bw == 0) {
+				task_rq_unlock(rq, p, &rf);
+				return -EPERM;
+			}
+		}
+#endif
+	}
+
+	/* Re-check policy now with rq lock held: */
+	if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
+		policy = oldpolicy = -1;
+		task_rq_unlock(rq, p, &rf);
+		goto recheck;
+	}
+
+	/*
+	 * If setscheduling to SCHED_DEADLINE (or changing the parameters
+	 * of a SCHED_DEADLINE task) we need to check if enough bandwidth
+	 * is available.
+	 */
+	if ((dl_policy(policy) || dl_task(p)) && sched_dl_overflow(p, policy, attr)) {
+		task_rq_unlock(rq, p, &rf);
+		return -EBUSY;
+	}
+
+	p->sched_reset_on_fork = reset_on_fork;
+	oldprio = p->prio;
+
+	if (pi) {
+		/*
+		 * Take priority boosted tasks into account. If the new
+		 * effective priority is unchanged, we just store the new
+		 * normal parameters and do not touch the scheduler class and
+		 * the runqueue. This will be done when the task deboost
+		 * itself.
+		 */
+		new_effective_prio = rt_effective_prio(p, newprio);
+		if (new_effective_prio == oldprio)
+			queue_flags &= ~DEQUEUE_MOVE;
+	}
+
+	queued = task_on_rq_queued(p);
+	running = task_current(rq, p);
+	if (queued)
+		dequeue_task(rq, p, queue_flags);
+	if (running)
+		put_prev_task(rq, p);
+
+	prev_class = p->sched_class;
+	__setscheduler(rq, p, attr, pi);
+
+	if (queued) {
+		/*
+		 * We enqueue to tail when the priority of a task is
+		 * increased (user space view).
+		 */
+		if (oldprio < p->prio)
+			queue_flags |= ENQUEUE_HEAD;
+
+		enqueue_task(rq, p, queue_flags);
+	}
+	if (running)
+		set_curr_task(rq, p);
+
+	check_class_changed(rq, p, prev_class, oldprio);
+
+	/* Avoid rq from going away on us: */
+	preempt_disable();
+	task_rq_unlock(rq, p, &rf);
+
+	if (pi)
+		rt_mutex_adjust_pi(p);
+
+	/* Run balance callbacks after we've adjusted the PI chain: */
+	balance_callback(rq);
+	preempt_enable();
+
+	return 0;
+}
+
+static int _sched_setscheduler(struct task_struct *p, int policy,
+			       const struct sched_param *param, bool check)
+{
+	struct sched_attr attr = {
+		.sched_policy   = policy,
+		.sched_priority = param->sched_priority,
+		.sched_nice	= PRIO_TO_NICE(p->static_prio),
+	};
+
+	/* Fixup the legacy SCHED_RESET_ON_FORK hack. */
+	if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
+		attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
+		policy &= ~SCHED_RESET_ON_FORK;
+		attr.sched_policy = policy;
+	}
+
+	return __sched_setscheduler(p, &attr, check, true);
+}
+/**
+ * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
+ * @p: the task in question.
+ * @policy: new policy.
+ * @param: structure containing the new RT priority.
+ *
+ * Return: 0 on success. An error code otherwise.
+ *
+ * NOTE that the task may be already dead.
+ */
+int sched_setscheduler(struct task_struct *p, int policy,
+		       const struct sched_param *param)
+{
+	return _sched_setscheduler(p, policy, param, true);
+}
+EXPORT_SYMBOL_GPL(sched_setscheduler);
+
+int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
+{
+	return __sched_setscheduler(p, attr, true, true);
+}
+EXPORT_SYMBOL_GPL(sched_setattr);
+
+int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr)
+{
+	return __sched_setscheduler(p, attr, false, true);
+}
+
+/**
+ * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
+ * @p: the task in question.
+ * @policy: new policy.
+ * @param: structure containing the new RT priority.
+ *
+ * Just like sched_setscheduler, only don't bother checking if the
+ * current context has permission.  For example, this is needed in
+ * stop_machine(): we create temporary high priority worker threads,
+ * but our caller might not have that capability.
+ *
+ * Return: 0 on success. An error code otherwise.
+ */
+int sched_setscheduler_nocheck(struct task_struct *p, int policy,
+			       const struct sched_param *param)
+{
+	return _sched_setscheduler(p, policy, param, false);
+}
+EXPORT_SYMBOL_GPL(sched_setscheduler_nocheck);
+
+static int
+do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
+{
+	struct sched_param lparam;
+	struct task_struct *p;
+	int retval;
+
+	if (!param || pid < 0)
+		return -EINVAL;
+	if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
+		return -EFAULT;
+
+	rcu_read_lock();
+	retval = -ESRCH;
+	p = find_process_by_pid(pid);
+	if (p != NULL)
+		retval = sched_setscheduler(p, policy, &lparam);
+	rcu_read_unlock();
+
+	return retval;
+}
+
+/*
+ * Mimics kernel/events/core.c perf_copy_attr().
+ */
+static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr)
+{
+	u32 size;
+	int ret;
+
+	if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0))
+		return -EFAULT;
+
+	/* Zero the full structure, so that a short copy will be nice: */
+	memset(attr, 0, sizeof(*attr));
+
+	ret = get_user(size, &uattr->size);
+	if (ret)
+		return ret;
+
+	/* Bail out on silly large: */
+	if (size > PAGE_SIZE)
+		goto err_size;
+
+	/* ABI compatibility quirk: */
+	if (!size)
+		size = SCHED_ATTR_SIZE_VER0;
+
+	if (size < SCHED_ATTR_SIZE_VER0)
+		goto err_size;
+
+	/*
+	 * If we're handed a bigger struct than we know of,
+	 * ensure all the unknown bits are 0 - i.e. new
+	 * user-space does not rely on any kernel feature
+	 * extensions we dont know about yet.
+	 */
+	if (size > sizeof(*attr)) {
+		unsigned char __user *addr;
+		unsigned char __user *end;
+		unsigned char val;
+
+		addr = (void __user *)uattr + sizeof(*attr);
+		end  = (void __user *)uattr + size;
+
+		for (; addr < end; addr++) {
+			ret = get_user(val, addr);
+			if (ret)
+				return ret;
+			if (val)
+				goto err_size;
+		}
+		size = sizeof(*attr);
+	}
+
+	ret = copy_from_user(attr, uattr, size);
+	if (ret)
+		return -EFAULT;
+
+	/*
+	 * XXX: Do we want to be lenient like existing syscalls; or do we want
+	 * to be strict and return an error on out-of-bounds values?
+	 */
+	attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
+
+	return 0;
+
+err_size:
+	put_user(sizeof(*attr), &uattr->size);
+	return -E2BIG;
+}
+
+/**
+ * sys_sched_setscheduler - set/change the scheduler policy and RT priority
+ * @pid: the pid in question.
+ * @policy: new policy.
+ * @param: structure containing the new RT priority.
+ *
+ * Return: 0 on success. An error code otherwise.
+ */
+SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, struct sched_param __user *, param)
+{
+	if (policy < 0)
+		return -EINVAL;
+
+	return do_sched_setscheduler(pid, policy, param);
+}
+
+/**
+ * sys_sched_setparam - set/change the RT priority of a thread
+ * @pid: the pid in question.
+ * @param: structure containing the new RT priority.
+ *
+ * Return: 0 on success. An error code otherwise.
+ */
+SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
+{
+	return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
+}
+
+/**
+ * sys_sched_setattr - same as above, but with extended sched_attr
+ * @pid: the pid in question.
+ * @uattr: structure containing the extended parameters.
+ * @flags: for future extension.
+ */
+SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
+			       unsigned int, flags)
+{
+	struct sched_attr attr;
+	struct task_struct *p;
+	int retval;
+
+	if (!uattr || pid < 0 || flags)
+		return -EINVAL;
+
+	retval = sched_copy_attr(uattr, &attr);
+	if (retval)
+		return retval;
+
+	if ((int)attr.sched_policy < 0)
+		return -EINVAL;
+
+	rcu_read_lock();
+	retval = -ESRCH;
+	p = find_process_by_pid(pid);
+	if (p != NULL)
+		retval = sched_setattr(p, &attr);
+	rcu_read_unlock();
+
+	return retval;
+}
+
+/**
+ * sys_sched_getscheduler - get the policy (scheduling class) of a thread
+ * @pid: the pid in question.
+ *
+ * Return: On success, the policy of the thread. Otherwise, a negative error
+ * code.
+ */
+SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
+{
+	struct task_struct *p;
+	int retval;
+
+	if (pid < 0)
+		return -EINVAL;
+
+	retval = -ESRCH;
+	rcu_read_lock();
+	p = find_process_by_pid(pid);
+	if (p) {
+		retval = security_task_getscheduler(p);
+		if (!retval)
+			retval = p->policy
+				| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
+	}
+	rcu_read_unlock();
+	return retval;
+}
+
+/**
+ * sys_sched_getparam - get the RT priority of a thread
+ * @pid: the pid in question.
+ * @param: structure containing the RT priority.
+ *
+ * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
+ * code.
+ */
+SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
+{
+	struct sched_param lp = { .sched_priority = 0 };
+	struct task_struct *p;
+	int retval;
+
+	if (!param || pid < 0)
+		return -EINVAL;
+
+	rcu_read_lock();
+	p = find_process_by_pid(pid);
+	retval = -ESRCH;
+	if (!p)
+		goto out_unlock;
+
+	retval = security_task_getscheduler(p);
+	if (retval)
+		goto out_unlock;
+
+	if (task_has_rt_policy(p))
+		lp.sched_priority = p->rt_priority;
+	rcu_read_unlock();
+
+	/*
+	 * This one might sleep, we cannot do it with a spinlock held ...
+	 */
+	retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
+
+	return retval;
+
+out_unlock:
+	rcu_read_unlock();
+	return retval;
+}
+
+static int sched_read_attr(struct sched_attr __user *uattr,
+			   struct sched_attr *attr,
+			   unsigned int usize)
+{
+	int ret;
+
+	if (!access_ok(VERIFY_WRITE, uattr, usize))
+		return -EFAULT;
+
+	/*
+	 * If we're handed a smaller struct than we know of,
+	 * ensure all the unknown bits are 0 - i.e. old
+	 * user-space does not get uncomplete information.
+	 */
+	if (usize < sizeof(*attr)) {
+		unsigned char *addr;
+		unsigned char *end;
+
+		addr = (void *)attr + usize;
+		end  = (void *)attr + sizeof(*attr);
+
+		for (; addr < end; addr++) {
+			if (*addr)
+				return -EFBIG;
+		}
+
+		attr->size = usize;
+	}
+
+	ret = copy_to_user(uattr, attr, attr->size);
+	if (ret)
+		return -EFAULT;
+
+	return 0;
+}
+
+/**
+ * sys_sched_getattr - similar to sched_getparam, but with sched_attr
+ * @pid: the pid in question.
+ * @uattr: structure containing the extended parameters.
+ * @size: sizeof(attr) for fwd/bwd comp.
+ * @flags: for future extension.
+ */
+SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
+		unsigned int, size, unsigned int, flags)
+{
+	struct sched_attr attr = {
+		.size = sizeof(struct sched_attr),
+	};
+	struct task_struct *p;
+	int retval;
+
+	if (!uattr || pid < 0 || size > PAGE_SIZE ||
+	    size < SCHED_ATTR_SIZE_VER0 || flags)
+		return -EINVAL;
+
+	rcu_read_lock();
+	p = find_process_by_pid(pid);
+	retval = -ESRCH;
+	if (!p)
+		goto out_unlock;
+
+	retval = security_task_getscheduler(p);
+	if (retval)
+		goto out_unlock;
+
+	attr.sched_policy = p->policy;
+	if (p->sched_reset_on_fork)
+		attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
+	if (task_has_dl_policy(p))
+		__getparam_dl(p, &attr);
+	else if (task_has_rt_policy(p))
+		attr.sched_priority = p->rt_priority;
+	else
+		attr.sched_nice = task_nice(p);
+
+	rcu_read_unlock();
+
+	retval = sched_read_attr(uattr, &attr, size);
+	return retval;
+
+out_unlock:
+	rcu_read_unlock();
+	return retval;
+}
+
+long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
+{
+	cpumask_var_t cpus_allowed, new_mask;
+	struct task_struct *p;
+	int retval;
+
+	rcu_read_lock();
+
+	p = find_process_by_pid(pid);
+	if (!p) {
+		rcu_read_unlock();
+		return -ESRCH;
+	}
+
+	/* Prevent p going away */
+	get_task_struct(p);
+	rcu_read_unlock();
+
+	if (p->flags & PF_NO_SETAFFINITY) {
+		retval = -EINVAL;
+		goto out_put_task;
+	}
+	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
+		retval = -ENOMEM;
+		goto out_put_task;
+	}
+	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
+		retval = -ENOMEM;
+		goto out_free_cpus_allowed;
+	}
+	retval = -EPERM;
+	if (!check_same_owner(p)) {
+		rcu_read_lock();
+		if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
+			rcu_read_unlock();
+			goto out_free_new_mask;
+		}
+		rcu_read_unlock();
+	}
+
+	retval = security_task_setscheduler(p);
+	if (retval)
+		goto out_free_new_mask;
+
+
+	cpuset_cpus_allowed(p, cpus_allowed);
+	cpumask_and(new_mask, in_mask, cpus_allowed);
+
+	/*
+	 * Since bandwidth control happens on root_domain basis,
+	 * if admission test is enabled, we only admit -deadline
+	 * tasks allowed to run on all the CPUs in the task's
+	 * root_domain.
+	 */
+#ifdef CONFIG_SMP
+	if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
+		rcu_read_lock();
+		if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
+			retval = -EBUSY;
+			rcu_read_unlock();
+			goto out_free_new_mask;
+		}
+		rcu_read_unlock();
+	}
+#endif
+again:
+	retval = __set_cpus_allowed_ptr(p, new_mask, true);
+
+	if (!retval) {
+		cpuset_cpus_allowed(p, cpus_allowed);
+		if (!cpumask_subset(new_mask, cpus_allowed)) {
+			/*
+			 * We must have raced with a concurrent cpuset
+			 * update. Just reset the cpus_allowed to the
+			 * cpuset's cpus_allowed
+			 */
+			cpumask_copy(new_mask, cpus_allowed);
+			goto again;
+		}
+	}
+out_free_new_mask:
+	free_cpumask_var(new_mask);
+out_free_cpus_allowed:
+	free_cpumask_var(cpus_allowed);
+out_put_task:
+	put_task_struct(p);
+	return retval;
+}
+
+static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
+			     struct cpumask *new_mask)
+{
+	if (len < cpumask_size())
+		cpumask_clear(new_mask);
+	else if (len > cpumask_size())
+		len = cpumask_size();
+
+	return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
+}
+
+/**
+ * sys_sched_setaffinity - set the CPU affinity of a process
+ * @pid: pid of the process
+ * @len: length in bytes of the bitmask pointed to by user_mask_ptr
+ * @user_mask_ptr: user-space pointer to the new CPU mask
+ *
+ * Return: 0 on success. An error code otherwise.
+ */
+SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
+		unsigned long __user *, user_mask_ptr)
+{
+	cpumask_var_t new_mask;
+	int retval;
+
+	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
+		return -ENOMEM;
+
+	retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
+	if (retval == 0)
+		retval = sched_setaffinity(pid, new_mask);
+	free_cpumask_var(new_mask);
+	return retval;
+}
+
+long sched_getaffinity(pid_t pid, struct cpumask *mask)
+{
+	struct task_struct *p;
+	unsigned long flags;
+	int retval;
+
+	rcu_read_lock();
+
+	retval = -ESRCH;
+	p = find_process_by_pid(pid);
+	if (!p)
+		goto out_unlock;
+
+	retval = security_task_getscheduler(p);
+	if (retval)
+		goto out_unlock;
+
+	raw_spin_lock_irqsave(&p->pi_lock, flags);
+	cpumask_and(mask, &p->cpus_allowed, cpu_active_mask);
+	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+
+out_unlock:
+	rcu_read_unlock();
+
+	return retval;
+}
+
+/**
+ * sys_sched_getaffinity - get the CPU affinity of a process
+ * @pid: pid of the process
+ * @len: length in bytes of the bitmask pointed to by user_mask_ptr
+ * @user_mask_ptr: user-space pointer to hold the current CPU mask
+ *
+ * Return: size of CPU mask copied to user_mask_ptr on success. An
+ * error code otherwise.
+ */
+SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
+		unsigned long __user *, user_mask_ptr)
+{
+	int ret;
+	cpumask_var_t mask;
+
+	if ((len * BITS_PER_BYTE) < nr_cpu_ids)
+		return -EINVAL;
+	if (len & (sizeof(unsigned long)-1))
+		return -EINVAL;
+
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+		return -ENOMEM;
+
+	ret = sched_getaffinity(pid, mask);
+	if (ret == 0) {
+		unsigned int retlen = min(len, cpumask_size());
+
+		if (copy_to_user(user_mask_ptr, mask, retlen))
+			ret = -EFAULT;
+		else
+			ret = retlen;
+	}
+	free_cpumask_var(mask);
+
+	return ret;
+}
+
+/**
+ * sys_sched_yield - yield the current processor to other threads.
+ *
+ * This function yields the current CPU to other tasks. If there are no
+ * other threads running on this CPU then this function will return.
+ *
+ * Return: 0.
+ */
+static void do_sched_yield(void)
+{
+	struct rq_flags rf;
+	struct rq *rq;
+
+	local_irq_disable();
+	rq = this_rq();
+	rq_lock(rq, &rf);
+
+	schedstat_inc(rq->yld_count);
+	current->sched_class->yield_task(rq);
+
+	preempt_disable();
+	rq_unlock_irq(rq, &rf);
+	sched_preempt_enable_no_resched();
+
+	schedule();
+}
+
+SYSCALL_DEFINE0(sched_yield)
+{
+	do_sched_yield();
+	return 0;
+}
+
+#ifndef CONFIG_PREEMPT
+int __sched _cond_resched(void)
+{
+	if (should_resched(0)) {
+		preempt_schedule_common();
+		return 1;
+	}
+	rcu_all_qs();
+	return 0;
+}
+EXPORT_SYMBOL(_cond_resched);
+#endif
+
+/*
+ * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
+ * call schedule, and on return reacquire the lock.
+ *
+ * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
+ * operations here to prevent schedule() from being called twice (once via
+ * spin_unlock(), once by hand).
+ */
+int __cond_resched_lock(spinlock_t *lock)
+{
+	int resched = should_resched(PREEMPT_LOCK_OFFSET);
+	int ret = 0;
+
+	lockdep_assert_held(lock);
+
+	if (spin_needbreak(lock) || resched) {
+		spin_unlock(lock);
+		if (resched)
+			preempt_schedule_common();
+		else
+			cpu_relax();
+		ret = 1;
+		spin_lock(lock);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(__cond_resched_lock);
+
+/**
+ * yield - yield the current processor to other threads.
+ *
+ * Do not ever use this function, there's a 99% chance you're doing it wrong.
+ *
+ * The scheduler is at all times free to pick the calling task as the most
+ * eligible task to run, if removing the yield() call from your code breaks
+ * it, its already broken.
+ *
+ * Typical broken usage is:
+ *
+ * while (!event)
+ *	yield();
+ *
+ * where one assumes that yield() will let 'the other' process run that will
+ * make event true. If the current task is a SCHED_FIFO task that will never
+ * happen. Never use yield() as a progress guarantee!!
+ *
+ * If you want to use yield() to wait for something, use wait_event().
+ * If you want to use yield() to be 'nice' for others, use cond_resched().
+ * If you still want to use yield(), do not!
+ */
+void __sched yield(void)
+{
+	set_current_state(TASK_RUNNING);
+	do_sched_yield();
+}
+EXPORT_SYMBOL(yield);
+
+/**
+ * yield_to - yield the current processor to another thread in
+ * your thread group, or accelerate that thread toward the
+ * processor it's on.
+ * @p: target task
+ * @preempt: whether task preemption is allowed or not
+ *
+ * It's the caller's job to ensure that the target task struct
+ * can't go away on us before we can do any checks.
+ *
+ * Return:
+ *	true (>0) if we indeed boosted the target task.
+ *	false (0) if we failed to boost the target.
+ *	-ESRCH if there's no task to yield to.
+ */
+int __sched yield_to(struct task_struct *p, bool preempt)
+{
+	struct task_struct *curr = current;
+	struct rq *rq, *p_rq;
+	unsigned long flags;
+	int yielded = 0;
+
+	local_irq_save(flags);
+	rq = this_rq();
+
+again:
+	p_rq = task_rq(p);
+	/*
+	 * If we're the only runnable task on the rq and target rq also
+	 * has only one task, there's absolutely no point in yielding.
+	 */
+	if (rq->nr_running == 1 && p_rq->nr_running == 1) {
+		yielded = -ESRCH;
+		goto out_irq;
+	}
+
+	double_rq_lock(rq, p_rq);
+	if (task_rq(p) != p_rq) {
+		double_rq_unlock(rq, p_rq);
+		goto again;
+	}
+
+	if (!curr->sched_class->yield_to_task)
+		goto out_unlock;
+
+	if (curr->sched_class != p->sched_class)
+		goto out_unlock;
+
+	if (task_running(p_rq, p) || p->state)
+		goto out_unlock;
+
+	yielded = curr->sched_class->yield_to_task(rq, p, preempt);
+	if (yielded) {
+		schedstat_inc(rq->yld_count);
+		/*
+		 * Make p's CPU reschedule; pick_next_entity takes care of
+		 * fairness.
+		 */
+		if (preempt && rq != p_rq)
+			resched_curr(p_rq);
+	}
+
+out_unlock:
+	double_rq_unlock(rq, p_rq);
+out_irq:
+	local_irq_restore(flags);
+
+	if (yielded > 0)
+		schedule();
+
+	return yielded;
+}
+EXPORT_SYMBOL_GPL(yield_to);
+
+int io_schedule_prepare(void)
+{
+	int old_iowait = current->in_iowait;
+
+	current->in_iowait = 1;
+	blk_schedule_flush_plug(current);
+
+	return old_iowait;
+}
+
+void io_schedule_finish(int token)
+{
+	current->in_iowait = token;
+}
+
+/*
+ * This task is about to go to sleep on IO. Increment rq->nr_iowait so
+ * that process accounting knows that this is a task in IO wait state.
+ */
+long __sched io_schedule_timeout(long timeout)
+{
+	int token;
+	long ret;
+
+	token = io_schedule_prepare();
+	ret = schedule_timeout(timeout);
+	io_schedule_finish(token);
+
+	return ret;
+}
+EXPORT_SYMBOL(io_schedule_timeout);
+
+void __sched io_schedule(void)
+{
+	int token;
+
+	token = io_schedule_prepare();
+	schedule();
+	io_schedule_finish(token);
+}
+EXPORT_SYMBOL(io_schedule);
+
+/**
+ * sys_sched_get_priority_max - return maximum RT priority.
+ * @policy: scheduling class.
+ *
+ * Return: On success, this syscall returns the maximum
+ * rt_priority that can be used by a given scheduling class.
+ * On failure, a negative error code is returned.
+ */
+SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
+{
+	int ret = -EINVAL;
+
+	switch (policy) {
+	case SCHED_FIFO:
+	case SCHED_RR:
+		ret = MAX_USER_RT_PRIO-1;
+		break;
+	case SCHED_DEADLINE:
+	case SCHED_NORMAL:
+	case SCHED_BATCH:
+	case SCHED_IDLE:
+		ret = 0;
+		break;
+	}
+	return ret;
+}
+
+/**
+ * sys_sched_get_priority_min - return minimum RT priority.
+ * @policy: scheduling class.
+ *
+ * Return: On success, this syscall returns the minimum
+ * rt_priority that can be used by a given scheduling class.
+ * On failure, a negative error code is returned.
+ */
+SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
+{
+	int ret = -EINVAL;
+
+	switch (policy) {
+	case SCHED_FIFO:
+	case SCHED_RR:
+		ret = 1;
+		break;
+	case SCHED_DEADLINE:
+	case SCHED_NORMAL:
+	case SCHED_BATCH:
+	case SCHED_IDLE:
+		ret = 0;
+	}
+	return ret;
+}
+
+static int sched_rr_get_interval(pid_t pid, struct timespec64 *t)
+{
+	struct task_struct *p;
+	unsigned int time_slice;
+	struct rq_flags rf;
+	struct rq *rq;
+	int retval;
+
+	if (pid < 0)
+		return -EINVAL;
+
+	retval = -ESRCH;
+	rcu_read_lock();
+	p = find_process_by_pid(pid);
+	if (!p)
+		goto out_unlock;
+
+	retval = security_task_getscheduler(p);
+	if (retval)
+		goto out_unlock;
+
+	rq = task_rq_lock(p, &rf);
+	time_slice = 0;
+	if (p->sched_class->get_rr_interval)
+		time_slice = p->sched_class->get_rr_interval(rq, p);
+	task_rq_unlock(rq, p, &rf);
+
+	rcu_read_unlock();
+	jiffies_to_timespec64(time_slice, t);
+	return 0;
+
+out_unlock:
+	rcu_read_unlock();
+	return retval;
+}
+
+/**
+ * sys_sched_rr_get_interval - return the default timeslice of a process.
+ * @pid: pid of the process.
+ * @interval: userspace pointer to the timeslice value.
+ *
+ * this syscall writes the default timeslice value of a given process
+ * into the user-space timespec buffer. A value of '0' means infinity.
+ *
+ * Return: On success, 0 and the timeslice is in @interval. Otherwise,
+ * an error code.
+ */
+SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
+		struct timespec __user *, interval)
+{
+	struct timespec64 t;
+	int retval = sched_rr_get_interval(pid, &t);
+
+	if (retval == 0)
+		retval = put_timespec64(&t, interval);
+
+	return retval;
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE2(sched_rr_get_interval,
+		       compat_pid_t, pid,
+		       struct compat_timespec __user *, interval)
+{
+	struct timespec64 t;
+	int retval = sched_rr_get_interval(pid, &t);
+
+	if (retval == 0)
+		retval = compat_put_timespec64(&t, interval);
+	return retval;
+}
+#endif
+
+void sched_show_task(struct task_struct *p)
+{
+	unsigned long free = 0;
+	int ppid;
+
+	if (!try_get_task_stack(p))
+		return;
+
+	printk(KERN_INFO "%-15.15s %c", p->comm, task_state_to_char(p));
+
+	if (p->state == TASK_RUNNING)
+		printk(KERN_CONT "  running task    ");
+#ifdef CONFIG_DEBUG_STACK_USAGE
+	free = stack_not_used(p);
+#endif
+	ppid = 0;
+	rcu_read_lock();
+	if (pid_alive(p))
+		ppid = task_pid_nr(rcu_dereference(p->real_parent));
+	rcu_read_unlock();
+	printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
+		task_pid_nr(p), ppid,
+		(unsigned long)task_thread_info(p)->flags);
+
+	print_worker_info(KERN_INFO, p);
+	show_stack(p, NULL);
+	put_task_stack(p);
+}
+EXPORT_SYMBOL_GPL(sched_show_task);
+
+static inline bool
+state_filter_match(unsigned long state_filter, struct task_struct *p)
+{
+	/* no filter, everything matches */
+	if (!state_filter)
+		return true;
+
+	/* filter, but doesn't match */
+	if (!(p->state & state_filter))
+		return false;
+
+	/*
+	 * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows
+	 * TASK_KILLABLE).
+	 */
+	if (state_filter == TASK_UNINTERRUPTIBLE && p->state == TASK_IDLE)
+		return false;
+
+	return true;
+}
+
+
+void show_state_filter(unsigned long state_filter)
+{
+	struct task_struct *g, *p;
+
+#if BITS_PER_LONG == 32
+	printk(KERN_INFO
+		"  task                PC stack   pid father\n");
+#else
+	printk(KERN_INFO
+		"  task                        PC stack   pid father\n");
+#endif
+	rcu_read_lock();
+	for_each_process_thread(g, p) {
+		/*
+		 * reset the NMI-timeout, listing all files on a slow
+		 * console might take a lot of time:
+		 * Also, reset softlockup watchdogs on all CPUs, because
+		 * another CPU might be blocked waiting for us to process
+		 * an IPI.
+		 */
+		touch_nmi_watchdog();
+		touch_all_softlockup_watchdogs();
+		if (state_filter_match(state_filter, p))
+			sched_show_task(p);
+	}
+
+#ifdef CONFIG_SCHED_DEBUG
+	if (!state_filter)
+		sysrq_sched_debug_show();
+#endif
+	rcu_read_unlock();
+	/*
+	 * Only show locks if all tasks are dumped:
+	 */
+	if (!state_filter)
+		debug_show_all_locks();
+}
+
+/**
+ * init_idle - set up an idle thread for a given CPU
+ * @idle: task in question
+ * @cpu: CPU the idle task belongs to
+ *
+ * NOTE: this function does not set the idle thread's NEED_RESCHED
+ * flag, to make booting more robust.
+ */
+void init_idle(struct task_struct *idle, int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	unsigned long flags;
+
+	__sched_fork(0, idle);
+
+	raw_spin_lock_irqsave(&idle->pi_lock, flags);
+	raw_spin_lock(&rq->lock);
+
+	idle->state = TASK_RUNNING;
+	idle->se.exec_start = sched_clock();
+	idle->flags |= PF_IDLE;
+
+	kasan_unpoison_task_stack(idle);
+
+#ifdef CONFIG_SMP
+	/*
+	 * Its possible that init_idle() gets called multiple times on a task,
+	 * in that case do_set_cpus_allowed() will not do the right thing.
+	 *
+	 * And since this is boot we can forgo the serialization.
+	 */
+	set_cpus_allowed_common(idle, cpumask_of(cpu));
+#endif
+	/*
+	 * We're having a chicken and egg problem, even though we are
+	 * holding rq->lock, the CPU isn't yet set to this CPU so the
+	 * lockdep check in task_group() will fail.
+	 *
+	 * Similar case to sched_fork(). / Alternatively we could
+	 * use task_rq_lock() here and obtain the other rq->lock.
+	 *
+	 * Silence PROVE_RCU
+	 */
+	rcu_read_lock();
+	__set_task_cpu(idle, cpu);
+	rcu_read_unlock();
+
+	rq->curr = rq->idle = idle;
+	idle->on_rq = TASK_ON_RQ_QUEUED;
+#ifdef CONFIG_SMP
+	idle->on_cpu = 1;
+#endif
+	raw_spin_unlock(&rq->lock);
+	raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
+
+	/* Set the preempt count _outside_ the spinlocks! */
+	init_idle_preempt_count(idle, cpu);
+
+	/*
+	 * The idle tasks have their own, simple scheduling class:
+	 */
+	idle->sched_class = &idle_sched_class;
+	ftrace_graph_init_idle_task(idle, cpu);
+	vtime_init_idle(idle, cpu);
+#ifdef CONFIG_SMP
+	sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
+#endif
+}
+
+#ifdef CONFIG_SMP
+
+int cpuset_cpumask_can_shrink(const struct cpumask *cur,
+			      const struct cpumask *trial)
+{
+	int ret = 1;
+
+	if (!cpumask_weight(cur))
+		return ret;
+
+	ret = dl_cpuset_cpumask_can_shrink(cur, trial);
+
+	return ret;
+}
+
+int task_can_attach(struct task_struct *p,
+		    const struct cpumask *cs_cpus_allowed)
+{
+	int ret = 0;
+
+	/*
+	 * Kthreads which disallow setaffinity shouldn't be moved
+	 * to a new cpuset; we don't want to change their CPU
+	 * affinity and isolating such threads by their set of
+	 * allowed nodes is unnecessary.  Thus, cpusets are not
+	 * applicable for such threads.  This prevents checking for
+	 * success of set_cpus_allowed_ptr() on all attached tasks
+	 * before cpus_allowed may be changed.
+	 */
+	if (p->flags & PF_NO_SETAFFINITY) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
+					      cs_cpus_allowed))
+		ret = dl_task_can_attach(p, cs_cpus_allowed);
+
+out:
+	return ret;
+}
+
+bool sched_smp_initialized __read_mostly;
+
+#ifdef CONFIG_NUMA_BALANCING
+/* Migrate current task p to target_cpu */
+int migrate_task_to(struct task_struct *p, int target_cpu)
+{
+	struct migration_arg arg = { p, target_cpu };
+	int curr_cpu = task_cpu(p);
+
+	if (curr_cpu == target_cpu)
+		return 0;
+
+	if (!cpumask_test_cpu(target_cpu, &p->cpus_allowed))
+		return -EINVAL;
+
+	/* TODO: This is not properly updating schedstats */
+
+	trace_sched_move_numa(p, curr_cpu, target_cpu);
+	return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
+}
+
+/*
+ * Requeue a task on a given node and accurately track the number of NUMA
+ * tasks on the runqueues
+ */
+void sched_setnuma(struct task_struct *p, int nid)
+{
+	bool queued, running;
+	struct rq_flags rf;
+	struct rq *rq;
+
+	rq = task_rq_lock(p, &rf);
+	queued = task_on_rq_queued(p);
+	running = task_current(rq, p);
+
+	if (queued)
+		dequeue_task(rq, p, DEQUEUE_SAVE);
+	if (running)
+		put_prev_task(rq, p);
+
+	p->numa_preferred_nid = nid;
+
+	if (queued)
+		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
+	if (running)
+		set_curr_task(rq, p);
+	task_rq_unlock(rq, p, &rf);
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * Ensure that the idle task is using init_mm right before its CPU goes
+ * offline.
+ */
+void idle_task_exit(void)
+{
+	struct mm_struct *mm = current->active_mm;
+
+	BUG_ON(cpu_online(smp_processor_id()));
+	BUG_ON(current != this_rq()->idle);
+
+	if (mm != &init_mm) {
+		switch_mm(mm, &init_mm, current);
+		finish_arch_post_lock_switch();
+	}
+
+	/* finish_cpu(), as ran on the BP, will clean up the active_mm state */
+}
+
+/*
+ * Since this CPU is going 'away' for a while, fold any nr_active delta
+ * we might have. Assumes we're called after migrate_tasks() so that the
+ * nr_active count is stable. We need to take the teardown thread which
+ * is calling this into account, so we hand in adjust = 1 to the load
+ * calculation.
+ *
+ * Also see the comment "Global load-average calculations".
+ */
+static void calc_load_migrate(struct rq *rq)
+{
+	long delta = calc_load_fold_active(rq, 1);
+	if (delta)
+		atomic_long_add(delta, &calc_load_tasks);
+}
+
+static void put_prev_task_fake(struct rq *rq, struct task_struct *prev)
+{
+}
+
+static const struct sched_class fake_sched_class = {
+	.put_prev_task = put_prev_task_fake,
+};
+
+static struct task_struct fake_task = {
+	/*
+	 * Avoid pull_{rt,dl}_task()
+	 */
+	.prio = MAX_PRIO + 1,
+	.sched_class = &fake_sched_class,
+};
+
+/*
+ * Migrate all tasks from the rq, sleeping tasks will be migrated by
+ * try_to_wake_up()->select_task_rq().
+ *
+ * Called with rq->lock held even though we'er in stop_machine() and
+ * there's no concurrency possible, we hold the required locks anyway
+ * because of lock validation efforts.
+ */
+static void migrate_tasks(struct rq *dead_rq, struct rq_flags *rf)
+{
+	struct rq *rq = dead_rq;
+	struct task_struct *next, *stop = rq->stop;
+	struct rq_flags orf = *rf;
+	int dest_cpu;
+
+	/*
+	 * Fudge the rq selection such that the below task selection loop
+	 * doesn't get stuck on the currently eligible stop task.
+	 *
+	 * We're currently inside stop_machine() and the rq is either stuck
+	 * in the stop_machine_cpu_stop() loop, or we're executing this code,
+	 * either way we should never end up calling schedule() until we're
+	 * done here.
+	 */
+	rq->stop = NULL;
+
+	/*
+	 * put_prev_task() and pick_next_task() sched
+	 * class method both need to have an up-to-date
+	 * value of rq->clock[_task]
+	 */
+	update_rq_clock(rq);
+
+	for (;;) {
+		/*
+		 * There's this thread running, bail when that's the only
+		 * remaining thread:
+		 */
+		if (rq->nr_running == 1)
+			break;
+
+		/*
+		 * pick_next_task() assumes pinned rq->lock:
+		 */
+		next = pick_next_task(rq, &fake_task, rf);
+		BUG_ON(!next);
+		put_prev_task(rq, next);
+
+		/*
+		 * Rules for changing task_struct::cpus_allowed are holding
+		 * both pi_lock and rq->lock, such that holding either
+		 * stabilizes the mask.
+		 *
+		 * Drop rq->lock is not quite as disastrous as it usually is
+		 * because !cpu_active at this point, which means load-balance
+		 * will not interfere. Also, stop-machine.
+		 */
+		rq_unlock(rq, rf);
+		raw_spin_lock(&next->pi_lock);
+		rq_relock(rq, rf);
+
+		/*
+		 * Since we're inside stop-machine, _nothing_ should have
+		 * changed the task, WARN if weird stuff happened, because in
+		 * that case the above rq->lock drop is a fail too.
+		 */
+		if (WARN_ON(task_rq(next) != rq || !task_on_rq_queued(next))) {
+			raw_spin_unlock(&next->pi_lock);
+			continue;
+		}
+
+		/* Find suitable destination for @next, with force if needed. */
+		dest_cpu = select_fallback_rq(dead_rq->cpu, next);
+		rq = __migrate_task(rq, rf, next, dest_cpu);
+		if (rq != dead_rq) {
+			rq_unlock(rq, rf);
+			rq = dead_rq;
+			*rf = orf;
+			rq_relock(rq, rf);
+		}
+		raw_spin_unlock(&next->pi_lock);
+	}
+
+	rq->stop = stop;
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
+void set_rq_online(struct rq *rq)
+{
+	if (!rq->online) {
+		const struct sched_class *class;
+
+		cpumask_set_cpu(rq->cpu, rq->rd->online);
+		rq->online = 1;
+
+		for_each_class(class) {
+			if (class->rq_online)
+				class->rq_online(rq);
+		}
+	}
+}
+
+void set_rq_offline(struct rq *rq)
+{
+	if (rq->online) {
+		const struct sched_class *class;
+
+		for_each_class(class) {
+			if (class->rq_offline)
+				class->rq_offline(rq);
+		}
+
+		cpumask_clear_cpu(rq->cpu, rq->rd->online);
+		rq->online = 0;
+	}
+}
+
+/*
+ * used to mark begin/end of suspend/resume:
+ */
+static int num_cpus_frozen;
+
+/*
+ * Update cpusets according to cpu_active mask.  If cpusets are
+ * disabled, cpuset_update_active_cpus() becomes a simple wrapper
+ * around partition_sched_domains().
+ *
+ * If we come here as part of a suspend/resume, don't touch cpusets because we
+ * want to restore it back to its original state upon resume anyway.
+ */
+static void cpuset_cpu_active(void)
+{
+	if (cpuhp_tasks_frozen) {
+		/*
+		 * num_cpus_frozen tracks how many CPUs are involved in suspend
+		 * resume sequence. As long as this is not the last online
+		 * operation in the resume sequence, just build a single sched
+		 * domain, ignoring cpusets.
+		 */
+		partition_sched_domains(1, NULL, NULL);
+		if (--num_cpus_frozen)
+			return;
+		/*
+		 * This is the last CPU online operation. So fall through and
+		 * restore the original sched domains by considering the
+		 * cpuset configurations.
+		 */
+		cpuset_force_rebuild();
+	}
+	cpuset_update_active_cpus();
+}
+
+static int cpuset_cpu_inactive(unsigned int cpu)
+{
+	if (!cpuhp_tasks_frozen) {
+		if (dl_cpu_busy(cpu))
+			return -EBUSY;
+		cpuset_update_active_cpus();
+	} else {
+		num_cpus_frozen++;
+		partition_sched_domains(1, NULL, NULL);
+	}
+	return 0;
+}
+
+int sched_cpu_activate(unsigned int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	struct rq_flags rf;
+
+#ifdef CONFIG_SCHED_SMT
+	/*
+	 * When going up, increment the number of cores with SMT present.
+	 */
+	if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
+		static_branch_inc_cpuslocked(&sched_smt_present);
+#endif
+	set_cpu_active(cpu, true);
+
+	if (sched_smp_initialized) {
+		sched_domains_numa_masks_set(cpu);
+		cpuset_cpu_active();
+	}
+
+	/*
+	 * Put the rq online, if not already. This happens:
+	 *
+	 * 1) In the early boot process, because we build the real domains
+	 *    after all CPUs have been brought up.
+	 *
+	 * 2) At runtime, if cpuset_cpu_active() fails to rebuild the
+	 *    domains.
+	 */
+	rq_lock_irqsave(rq, &rf);
+	if (rq->rd) {
+		BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
+		set_rq_online(rq);
+	}
+	rq_unlock_irqrestore(rq, &rf);
+
+	update_max_interval();
+
+	return 0;
+}
+
+int sched_cpu_deactivate(unsigned int cpu)
+{
+	int ret;
+
+	set_cpu_active(cpu, false);
+	/*
+	 * We've cleared cpu_active_mask, wait for all preempt-disabled and RCU
+	 * users of this state to go away such that all new such users will
+	 * observe it.
+	 *
+	 * Do sync before park smpboot threads to take care the rcu boost case.
+	 */
+	synchronize_rcu_mult(call_rcu, call_rcu_sched);
+
+#ifdef CONFIG_SCHED_SMT
+	/*
+	 * When going down, decrement the number of cores with SMT present.
+	 */
+	if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
+		static_branch_dec_cpuslocked(&sched_smt_present);
+#endif
+
+	if (!sched_smp_initialized)
+		return 0;
+
+	ret = cpuset_cpu_inactive(cpu);
+	if (ret) {
+		set_cpu_active(cpu, true);
+		return ret;
+	}
+	sched_domains_numa_masks_clear(cpu);
+	return 0;
+}
+
+static void sched_rq_cpu_starting(unsigned int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+
+	rq->calc_load_update = calc_load_update;
+	update_max_interval();
+}
+
+int sched_cpu_starting(unsigned int cpu)
+{
+	sched_rq_cpu_starting(cpu);
+	sched_tick_start(cpu);
+	return 0;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+int sched_cpu_dying(unsigned int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	struct rq_flags rf;
+
+	/* Handle pending wakeups and then migrate everything off */
+	sched_ttwu_pending();
+	sched_tick_stop(cpu);
+
+	rq_lock_irqsave(rq, &rf);
+	if (rq->rd) {
+		BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
+		set_rq_offline(rq);
+	}
+	migrate_tasks(rq, &rf);
+	BUG_ON(rq->nr_running != 1);
+	rq_unlock_irqrestore(rq, &rf);
+
+	calc_load_migrate(rq);
+	update_max_interval();
+	nohz_balance_exit_idle(rq);
+	hrtick_clear(rq);
+	return 0;
+}
+#endif
+
+void __init sched_init_smp(void)
+{
+	sched_init_numa();
+
+	/*
+	 * There's no userspace yet to cause hotplug operations; hence all the
+	 * CPU masks are stable and all blatant races in the below code cannot
+	 * happen. The hotplug lock is nevertheless taken to satisfy lockdep,
+	 * but there won't be any contention on it.
+	 */
+	cpus_read_lock();
+	mutex_lock(&sched_domains_mutex);
+	sched_init_domains(cpu_active_mask);
+	mutex_unlock(&sched_domains_mutex);
+	cpus_read_unlock();
+
+	/* Move init over to a non-isolated CPU */
+	if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0)
+		BUG();
+	sched_init_granularity();
+
+	init_sched_rt_class();
+	init_sched_dl_class();
+
+	sched_smp_initialized = true;
+}
+
+static int __init migration_init(void)
+{
+	sched_rq_cpu_starting(smp_processor_id());
+	return 0;
+}
+early_initcall(migration_init);
+
+#else
+void __init sched_init_smp(void)
+{
+	sched_init_granularity();
+}
+#endif /* CONFIG_SMP */
+
+int in_sched_functions(unsigned long addr)
+{
+	return in_lock_functions(addr) ||
+		(addr >= (unsigned long)__sched_text_start
+		&& addr < (unsigned long)__sched_text_end);
+}
+
+#ifdef CONFIG_CGROUP_SCHED
+/*
+ * Default task group.
+ * Every task in system belongs to this group at bootup.
+ */
+struct task_group root_task_group;
+LIST_HEAD(task_groups);
+
+/* Cacheline aligned slab cache for task_group */
+static struct kmem_cache *task_group_cache __read_mostly;
+#endif
+
+DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
+DECLARE_PER_CPU(cpumask_var_t, select_idle_mask);
+
+void __init sched_init(void)
+{
+	int i, j;
+	unsigned long alloc_size = 0, ptr;
+
+	wait_bit_init();
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+	alloc_size += 2 * nr_cpu_ids * sizeof(void **);
+#endif
+#ifdef CONFIG_RT_GROUP_SCHED
+	alloc_size += 2 * nr_cpu_ids * sizeof(void **);
+#endif
+	if (alloc_size) {
+		ptr = (unsigned long)kzalloc(alloc_size, GFP_NOWAIT);
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+		root_task_group.se = (struct sched_entity **)ptr;
+		ptr += nr_cpu_ids * sizeof(void **);
+
+		root_task_group.cfs_rq = (struct cfs_rq **)ptr;
+		ptr += nr_cpu_ids * sizeof(void **);
+
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+#ifdef CONFIG_RT_GROUP_SCHED
+		root_task_group.rt_se = (struct sched_rt_entity **)ptr;
+		ptr += nr_cpu_ids * sizeof(void **);
+
+		root_task_group.rt_rq = (struct rt_rq **)ptr;
+		ptr += nr_cpu_ids * sizeof(void **);
+
+#endif /* CONFIG_RT_GROUP_SCHED */
+	}
+#ifdef CONFIG_CPUMASK_OFFSTACK
+	for_each_possible_cpu(i) {
+		per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
+			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
+		per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node(
+			cpumask_size(), GFP_KERNEL, cpu_to_node(i));
+	}
+#endif /* CONFIG_CPUMASK_OFFSTACK */
+
+	init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime());
+	init_dl_bandwidth(&def_dl_bandwidth, global_rt_period(), global_rt_runtime());
+
+#ifdef CONFIG_SMP
+	init_defrootdomain();
+#endif
+
+#ifdef CONFIG_RT_GROUP_SCHED
+	init_rt_bandwidth(&root_task_group.rt_bandwidth,
+			global_rt_period(), global_rt_runtime());
+#endif /* CONFIG_RT_GROUP_SCHED */
+
+#ifdef CONFIG_CGROUP_SCHED
+	task_group_cache = KMEM_CACHE(task_group, 0);
+
+	list_add(&root_task_group.list, &task_groups);
+	INIT_LIST_HEAD(&root_task_group.children);
+	INIT_LIST_HEAD(&root_task_group.siblings);
+	autogroup_init(&init_task);
+#endif /* CONFIG_CGROUP_SCHED */
+
+	for_each_possible_cpu(i) {
+		struct rq *rq;
+
+		rq = cpu_rq(i);
+		raw_spin_lock_init(&rq->lock);
+		rq->nr_running = 0;
+		rq->calc_load_active = 0;
+		rq->calc_load_update = jiffies + LOAD_FREQ;
+		init_cfs_rq(&rq->cfs);
+		init_rt_rq(&rq->rt);
+		init_dl_rq(&rq->dl);
+#ifdef CONFIG_FAIR_GROUP_SCHED
+		root_task_group.shares = ROOT_TASK_GROUP_LOAD;
+		INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
+		rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
+		/*
+		 * How much CPU bandwidth does root_task_group get?
+		 *
+		 * In case of task-groups formed thr' the cgroup filesystem, it
+		 * gets 100% of the CPU resources in the system. This overall
+		 * system CPU resource is divided among the tasks of
+		 * root_task_group and its child task-groups in a fair manner,
+		 * based on each entity's (task or task-group's) weight
+		 * (se->load.weight).
+		 *
+		 * In other words, if root_task_group has 10 tasks of weight
+		 * 1024) and two child groups A0 and A1 (of weight 1024 each),
+		 * then A0's share of the CPU resource is:
+		 *
+		 *	A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
+		 *
+		 * We achieve this by letting root_task_group's tasks sit
+		 * directly in rq->cfs (i.e root_task_group->se[] = NULL).
+		 */
+		init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
+		init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
+		rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
+#ifdef CONFIG_RT_GROUP_SCHED
+		init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
+#endif
+
+		for (j = 0; j < CPU_LOAD_IDX_MAX; j++)
+			rq->cpu_load[j] = 0;
+
+#ifdef CONFIG_SMP
+		rq->sd = NULL;
+		rq->rd = NULL;
+		rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
+		rq->balance_callback = NULL;
+		rq->active_balance = 0;
+		rq->next_balance = jiffies;
+		rq->push_cpu = 0;
+		rq->cpu = i;
+		rq->online = 0;
+		rq->idle_stamp = 0;
+		rq->avg_idle = 2*sysctl_sched_migration_cost;
+		rq->max_idle_balance_cost = sysctl_sched_migration_cost;
+
+		INIT_LIST_HEAD(&rq->cfs_tasks);
+
+		rq_attach_root(rq, &def_root_domain);
+#ifdef CONFIG_NO_HZ_COMMON
+		rq->last_load_update_tick = jiffies;
+		rq->last_blocked_load_update_tick = jiffies;
+		atomic_set(&rq->nohz_flags, 0);
+#endif
+#endif /* CONFIG_SMP */
+		hrtick_rq_init(rq);
+		atomic_set(&rq->nr_iowait, 0);
+	}
+
+	set_load_weight(&init_task, false);
+
+	/*
+	 * The boot idle thread does lazy MMU switching as well:
+	 */
+	mmgrab(&init_mm);
+	enter_lazy_tlb(&init_mm, current);
+
+	/*
+	 * Make us the idle thread. Technically, schedule() should not be
+	 * called from this thread, however somewhere below it might be,
+	 * but because we are the idle thread, we just pick up running again
+	 * when this runqueue becomes "idle".
+	 */
+	init_idle(current, smp_processor_id());
+
+	calc_load_update = jiffies + LOAD_FREQ;
+
+#ifdef CONFIG_SMP
+	idle_thread_set_boot_cpu();
+#endif
+	init_sched_fair_class();
+
+	init_schedstats();
+
+	scheduler_running = 1;
+}
+
+#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
+static inline int preempt_count_equals(int preempt_offset)
+{
+	int nested = preempt_count() + rcu_preempt_depth();
+
+	return (nested == preempt_offset);
+}
+
+void __might_sleep(const char *file, int line, int preempt_offset)
+{
+	/*
+	 * Blocking primitives will set (and therefore destroy) current->state,
+	 * since we will exit with TASK_RUNNING make sure we enter with it,
+	 * otherwise we will destroy state.
+	 */
+	WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
+			"do not call blocking ops when !TASK_RUNNING; "
+			"state=%lx set at [<%p>] %pS\n",
+			current->state,
+			(void *)current->task_state_change,
+			(void *)current->task_state_change);
+
+	___might_sleep(file, line, preempt_offset);
+}
+EXPORT_SYMBOL(__might_sleep);
+
+void ___might_sleep(const char *file, int line, int preempt_offset)
+{
+	/* Ratelimiting timestamp: */
+	static unsigned long prev_jiffy;
+
+	unsigned long preempt_disable_ip;
+
+	/* WARN_ON_ONCE() by default, no rate limit required: */
+	rcu_sleep_check();
+
+	if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
+	     !is_idle_task(current)) ||
+	    system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING ||
+	    oops_in_progress)
+		return;
+
+	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
+		return;
+	prev_jiffy = jiffies;
+
+	/* Save this before calling printk(), since that will clobber it: */
+	preempt_disable_ip = get_preempt_disable_ip(current);
+
+	printk(KERN_ERR
+		"BUG: sleeping function called from invalid context at %s:%d\n",
+			file, line);
+	printk(KERN_ERR
+		"in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
+			in_atomic(), irqs_disabled(),
+			current->pid, current->comm);
+
+	if (task_stack_end_corrupted(current))
+		printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
+
+	debug_show_held_locks(current);
+	if (irqs_disabled())
+		print_irqtrace_events(current);
+	if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
+	    && !preempt_count_equals(preempt_offset)) {
+		pr_err("Preemption disabled at:");
+		print_ip_sym(preempt_disable_ip);
+		pr_cont("\n");
+	}
+	dump_stack();
+	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
+}
+EXPORT_SYMBOL(___might_sleep);
+#endif
+
+#ifdef CONFIG_MAGIC_SYSRQ
+void normalize_rt_tasks(void)
+{
+	struct task_struct *g, *p;
+	struct sched_attr attr = {
+		.sched_policy = SCHED_NORMAL,
+	};
+
+	read_lock(&tasklist_lock);
+	for_each_process_thread(g, p) {
+		/*
+		 * Only normalize user tasks:
+		 */
+		if (p->flags & PF_KTHREAD)
+			continue;
+
+		p->se.exec_start = 0;
+		schedstat_set(p->se.statistics.wait_start,  0);
+		schedstat_set(p->se.statistics.sleep_start, 0);
+		schedstat_set(p->se.statistics.block_start, 0);
+
+		if (!dl_task(p) && !rt_task(p)) {
+			/*
+			 * Renice negative nice level userspace
+			 * tasks back to 0:
+			 */
+			if (task_nice(p) < 0)
+				set_user_nice(p, 0);
+			continue;
+		}
+
+		__sched_setscheduler(p, &attr, false, false);
+	}
+	read_unlock(&tasklist_lock);
+}
+
+#endif /* CONFIG_MAGIC_SYSRQ */
+
+#if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
+/*
+ * These functions are only useful for the IA64 MCA handling, or kdb.
+ *
+ * They can only be called when the whole system has been
+ * stopped - every CPU needs to be quiescent, and no scheduling
+ * activity can take place. Using them for anything else would
+ * be a serious bug, and as a result, they aren't even visible
+ * under any other configuration.
+ */
+
+/**
+ * curr_task - return the current task for a given CPU.
+ * @cpu: the processor in question.
+ *
+ * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
+ *
+ * Return: The current task for @cpu.
+ */
+struct task_struct *curr_task(int cpu)
+{
+	return cpu_curr(cpu);
+}
+
+#endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
+
+#ifdef CONFIG_IA64
+/**
+ * set_curr_task - set the current task for a given CPU.
+ * @cpu: the processor in question.
+ * @p: the task pointer to set.
+ *
+ * Description: This function must only be used when non-maskable interrupts
+ * are serviced on a separate stack. It allows the architecture to switch the
+ * notion of the current task on a CPU in a non-blocking manner. This function
+ * must be called with all CPU's synchronized, and interrupts disabled, the
+ * and caller must save the original value of the current task (see
+ * curr_task() above) and restore that value before reenabling interrupts and
+ * re-starting the system.
+ *
+ * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
+ */
+void ia64_set_curr_task(int cpu, struct task_struct *p)
+{
+	cpu_curr(cpu) = p;
+}
+
+#endif
+
+#ifdef CONFIG_CGROUP_SCHED
+/* task_group_lock serializes the addition/removal of task groups */
+static DEFINE_SPINLOCK(task_group_lock);
+
+static void sched_free_group(struct task_group *tg)
+{
+	free_fair_sched_group(tg);
+	free_rt_sched_group(tg);
+	autogroup_free(tg);
+	kmem_cache_free(task_group_cache, tg);
+}
+
+/* allocate runqueue etc for a new task group */
+struct task_group *sched_create_group(struct task_group *parent)
+{
+	struct task_group *tg;
+
+	tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
+	if (!tg)
+		return ERR_PTR(-ENOMEM);
+
+	if (!alloc_fair_sched_group(tg, parent))
+		goto err;
+
+	if (!alloc_rt_sched_group(tg, parent))
+		goto err;
+
+	return tg;
+
+err:
+	sched_free_group(tg);
+	return ERR_PTR(-ENOMEM);
+}
+
+void sched_online_group(struct task_group *tg, struct task_group *parent)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&task_group_lock, flags);
+	list_add_rcu(&tg->list, &task_groups);
+
+	/* Root should already exist: */
+	WARN_ON(!parent);
+
+	tg->parent = parent;
+	INIT_LIST_HEAD(&tg->children);
+	list_add_rcu(&tg->siblings, &parent->children);
+	spin_unlock_irqrestore(&task_group_lock, flags);
+
+	online_fair_sched_group(tg);
+}
+
+/* rcu callback to free various structures associated with a task group */
+static void sched_free_group_rcu(struct rcu_head *rhp)
+{
+	/* Now it should be safe to free those cfs_rqs: */
+	sched_free_group(container_of(rhp, struct task_group, rcu));
+}
+
+void sched_destroy_group(struct task_group *tg)
+{
+	/* Wait for possible concurrent references to cfs_rqs complete: */
+	call_rcu(&tg->rcu, sched_free_group_rcu);
+}
+
+void sched_offline_group(struct task_group *tg)
+{
+	unsigned long flags;
+
+	/* End participation in shares distribution: */
+	unregister_fair_sched_group(tg);
+
+	spin_lock_irqsave(&task_group_lock, flags);
+	list_del_rcu(&tg->list);
+	list_del_rcu(&tg->siblings);
+	spin_unlock_irqrestore(&task_group_lock, flags);
+}
+
+static void sched_change_group(struct task_struct *tsk, int type)
+{
+	struct task_group *tg;
+
+	/*
+	 * All callers are synchronized by task_rq_lock(); we do not use RCU
+	 * which is pointless here. Thus, we pass "true" to task_css_check()
+	 * to prevent lockdep warnings.
+	 */
+	tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
+			  struct task_group, css);
+	tg = autogroup_task_group(tsk, tg);
+	tsk->sched_task_group = tg;
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+	if (tsk->sched_class->task_change_group)
+		tsk->sched_class->task_change_group(tsk, type);
+	else
+#endif
+		set_task_rq(tsk, task_cpu(tsk));
+}
+
+/*
+ * Change task's runqueue when it moves between groups.
+ *
+ * The caller of this function should have put the task in its new group by
+ * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect
+ * its new group.
+ */
+void sched_move_task(struct task_struct *tsk)
+{
+	int queued, running, queue_flags =
+		DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
+	struct rq_flags rf;
+	struct rq *rq;
+
+	rq = task_rq_lock(tsk, &rf);
+	update_rq_clock(rq);
+
+	running = task_current(rq, tsk);
+	queued = task_on_rq_queued(tsk);
+
+	if (queued)
+		dequeue_task(rq, tsk, queue_flags);
+	if (running)
+		put_prev_task(rq, tsk);
+
+	sched_change_group(tsk, TASK_MOVE_GROUP);
+
+	if (queued)
+		enqueue_task(rq, tsk, queue_flags);
+	if (running)
+		set_curr_task(rq, tsk);
+
+	task_rq_unlock(rq, tsk, &rf);
+}
+
+static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
+{
+	return css ? container_of(css, struct task_group, css) : NULL;
+}
+
+static struct cgroup_subsys_state *
+cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+	struct task_group *parent = css_tg(parent_css);
+	struct task_group *tg;
+
+	if (!parent) {
+		/* This is early initialization for the top cgroup */
+		return &root_task_group.css;
+	}
+
+	tg = sched_create_group(parent);
+	if (IS_ERR(tg))
+		return ERR_PTR(-ENOMEM);
+
+	return &tg->css;
+}
+
+/* Expose task group only after completing cgroup initialization */
+static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
+{
+	struct task_group *tg = css_tg(css);
+	struct task_group *parent = css_tg(css->parent);
+
+	if (parent)
+		sched_online_group(tg, parent);
+	return 0;
+}
+
+static void cpu_cgroup_css_released(struct cgroup_subsys_state *css)
+{
+	struct task_group *tg = css_tg(css);
+
+	sched_offline_group(tg);
+}
+
+static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
+{
+	struct task_group *tg = css_tg(css);
+
+	/*
+	 * Relies on the RCU grace period between css_released() and this.
+	 */
+	sched_free_group(tg);
+}
+
+/*
+ * This is called before wake_up_new_task(), therefore we really only
+ * have to set its group bits, all the other stuff does not apply.
+ */
+static void cpu_cgroup_fork(struct task_struct *task)
+{
+	struct rq_flags rf;
+	struct rq *rq;
+
+	rq = task_rq_lock(task, &rf);
+
+	update_rq_clock(rq);
+	sched_change_group(task, TASK_SET_GROUP);
+
+	task_rq_unlock(rq, task, &rf);
+}
+
+static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
+{
+	struct task_struct *task;
+	struct cgroup_subsys_state *css;
+	int ret = 0;
+
+	cgroup_taskset_for_each(task, css, tset) {
+#ifdef CONFIG_RT_GROUP_SCHED
+		if (!sched_rt_can_attach(css_tg(css), task))
+			return -EINVAL;
+#endif
+		/*
+		 * Serialize against wake_up_new_task() such that if its
+		 * running, we're sure to observe its full state.
+		 */
+		raw_spin_lock_irq(&task->pi_lock);
+		/*
+		 * Avoid calling sched_move_task() before wake_up_new_task()
+		 * has happened. This would lead to problems with PELT, due to
+		 * move wanting to detach+attach while we're not attached yet.
+		 */
+		if (task->state == TASK_NEW)
+			ret = -EINVAL;
+		raw_spin_unlock_irq(&task->pi_lock);
+
+		if (ret)
+			break;
+	}
+	return ret;
+}
+
+static void cpu_cgroup_attach(struct cgroup_taskset *tset)
+{
+	struct task_struct *task;
+	struct cgroup_subsys_state *css;
+
+	cgroup_taskset_for_each(task, css, tset)
+		sched_move_task(task);
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
+				struct cftype *cftype, u64 shareval)
+{
+	if (shareval > scale_load_down(ULONG_MAX))
+		shareval = MAX_SHARES;
+	return sched_group_set_shares(css_tg(css), scale_load(shareval));
+}
+
+static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
+			       struct cftype *cft)
+{
+	struct task_group *tg = css_tg(css);
+
+	return (u64) scale_load_down(tg->shares);
+}
+
+#ifdef CONFIG_CFS_BANDWIDTH
+static DEFINE_MUTEX(cfs_constraints_mutex);
+
+const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
+const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
+
+static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
+
+static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
+{
+	int i, ret = 0, runtime_enabled, runtime_was_enabled;
+	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
+
+	if (tg == &root_task_group)
+		return -EINVAL;
+
+	/*
+	 * Ensure we have at some amount of bandwidth every period.  This is
+	 * to prevent reaching a state of large arrears when throttled via
+	 * entity_tick() resulting in prolonged exit starvation.
+	 */
+	if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
+		return -EINVAL;
+
+	/*
+	 * Likewise, bound things on the otherside by preventing insane quota
+	 * periods.  This also allows us to normalize in computing quota
+	 * feasibility.
+	 */
+	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)
+		goto out_unlock;
+
+	runtime_enabled = quota != RUNTIME_INF;
+	runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
+	/*
+	 * If we need to toggle cfs_bandwidth_used, off->on must occur
+	 * before making related changes, and on->off must occur afterwards
+	 */
+	if (runtime_enabled && !runtime_was_enabled)
+		cfs_bandwidth_usage_inc();
+	raw_spin_lock_irq(&cfs_b->lock);
+	cfs_b->period = ns_to_ktime(period);
+	cfs_b->quota = quota;
+
+	__refill_cfs_bandwidth_runtime(cfs_b);
+
+	/* Restart the period timer (if active) to handle new period expiry: */
+	if (runtime_enabled)
+		start_cfs_bandwidth(cfs_b);
+
+	raw_spin_unlock_irq(&cfs_b->lock);
+
+	for_each_online_cpu(i) {
+		struct cfs_rq *cfs_rq = tg->cfs_rq[i];
+		struct rq *rq = cfs_rq->rq;
+		struct rq_flags rf;
+
+		rq_lock_irq(rq, &rf);
+		cfs_rq->runtime_enabled = runtime_enabled;
+		cfs_rq->runtime_remaining = 0;
+
+		if (cfs_rq->throttled)
+			unthrottle_cfs_rq(cfs_rq);
+		rq_unlock_irq(rq, &rf);
+	}
+	if (runtime_was_enabled && !runtime_enabled)
+		cfs_bandwidth_usage_dec();
+out_unlock:
+	mutex_unlock(&cfs_constraints_mutex);
+	put_online_cpus();
+
+	return ret;
+}
+
+int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
+{
+	u64 quota, period;
+
+	period = ktime_to_ns(tg->cfs_bandwidth.period);
+	if (cfs_quota_us < 0)
+		quota = RUNTIME_INF;
+	else if ((u64)cfs_quota_us <= U64_MAX / NSEC_PER_USEC)
+		quota = (u64)cfs_quota_us * NSEC_PER_USEC;
+	else
+		return -EINVAL;
+
+	return tg_set_cfs_bandwidth(tg, period, quota);
+}
+
+long tg_get_cfs_quota(struct task_group *tg)
+{
+	u64 quota_us;
+
+	if (tg->cfs_bandwidth.quota == RUNTIME_INF)
+		return -1;
+
+	quota_us = tg->cfs_bandwidth.quota;
+	do_div(quota_us, NSEC_PER_USEC);
+
+	return quota_us;
+}
+
+int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
+{
+	u64 quota, period;
+
+	if ((u64)cfs_period_us > U64_MAX / NSEC_PER_USEC)
+		return -EINVAL;
+
+	period = (u64)cfs_period_us * NSEC_PER_USEC;
+	quota = tg->cfs_bandwidth.quota;
+
+	return tg_set_cfs_bandwidth(tg, period, quota);
+}
+
+long tg_get_cfs_period(struct task_group *tg)
+{
+	u64 cfs_period_us;
+
+	cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
+	do_div(cfs_period_us, NSEC_PER_USEC);
+
+	return cfs_period_us;
+}
+
+static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
+				  struct cftype *cft)
+{
+	return tg_get_cfs_quota(css_tg(css));
+}
+
+static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
+				   struct cftype *cftype, s64 cfs_quota_us)
+{
+	return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
+}
+
+static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
+				   struct cftype *cft)
+{
+	return tg_get_cfs_period(css_tg(css));
+}
+
+static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
+				    struct cftype *cftype, u64 cfs_period_us)
+{
+	return tg_set_cfs_period(css_tg(css), cfs_period_us);
+}
+
+struct cfs_schedulable_data {
+	struct task_group *tg;
+	u64 period, quota;
+};
+
+/*
+ * normalize group quota/period to be quota/max_period
+ * note: units are usecs
+ */
+static u64 normalize_cfs_quota(struct task_group *tg,
+			       struct cfs_schedulable_data *d)
+{
+	u64 quota, period;
+
+	if (tg == d->tg) {
+		period = d->period;
+		quota = d->quota;
+	} else {
+		period = tg_get_cfs_period(tg);
+		quota = tg_get_cfs_quota(tg);
+	}
+
+	/* note: these should typically be equivalent */
+	if (quota == RUNTIME_INF || quota == -1)
+		return RUNTIME_INF;
+
+	return to_ratio(period, quota);
+}
+
+static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
+{
+	struct cfs_schedulable_data *d = data;
+	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
+	s64 quota = 0, parent_quota = -1;
+
+	if (!tg->parent) {
+		quota = RUNTIME_INF;
+	} else {
+		struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
+
+		quota = normalize_cfs_quota(tg, d);
+		parent_quota = parent_b->hierarchical_quota;
+
+		/*
+		 * Ensure max(child_quota) <= parent_quota.  On cgroup2,
+		 * always take the min.  On cgroup1, only inherit when no
+		 * limit is set:
+		 */
+		if (cgroup_subsys_on_dfl(cpu_cgrp_subsys)) {
+			quota = min(quota, parent_quota);
+		} else {
+			if (quota == RUNTIME_INF)
+				quota = parent_quota;
+			else if (parent_quota != RUNTIME_INF && quota > parent_quota)
+				return -EINVAL;
+		}
+	}
+	cfs_b->hierarchical_quota = quota;
+
+	return 0;
+}
+
+static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
+{
+	int ret;
+	struct cfs_schedulable_data data = {
+		.tg = tg,
+		.period = period,
+		.quota = quota,
+	};
+
+	if (quota != RUNTIME_INF) {
+		do_div(data.period, NSEC_PER_USEC);
+		do_div(data.quota, NSEC_PER_USEC);
+	}
+
+	rcu_read_lock();
+	ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
+	rcu_read_unlock();
+
+	return ret;
+}
+
+static int cpu_cfs_stat_show(struct seq_file *sf, void *v)
+{
+	struct task_group *tg = css_tg(seq_css(sf));
+	struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
+
+	seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
+	seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
+	seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
+
+	if (schedstat_enabled() && tg != &root_task_group) {
+		u64 ws = 0;
+		int i;
+
+		for_each_possible_cpu(i)
+			ws += schedstat_val(tg->se[i]->statistics.wait_sum);
+
+		seq_printf(sf, "wait_sum %llu\n", ws);
+	}
+
+	return 0;
+}
+#endif /* CONFIG_CFS_BANDWIDTH */
+#endif /* CONFIG_FAIR_GROUP_SCHED */
+
+#ifdef CONFIG_RT_GROUP_SCHED
+static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
+				struct cftype *cft, s64 val)
+{
+	return sched_group_set_rt_runtime(css_tg(css), val);
+}
+
+static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
+			       struct cftype *cft)
+{
+	return sched_group_rt_runtime(css_tg(css));
+}
+
+static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
+				    struct cftype *cftype, u64 rt_period_us)
+{
+	return sched_group_set_rt_period(css_tg(css), rt_period_us);
+}
+
+static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
+				   struct cftype *cft)
+{
+	return sched_group_rt_period(css_tg(css));
+}
+#endif /* CONFIG_RT_GROUP_SCHED */
+
+static struct cftype cpu_legacy_files[] = {
+#ifdef CONFIG_FAIR_GROUP_SCHED
+	{
+		.name = "shares",
+		.read_u64 = cpu_shares_read_u64,
+		.write_u64 = cpu_shares_write_u64,
+	},
+#endif
+#ifdef CONFIG_CFS_BANDWIDTH
+	{
+		.name = "cfs_quota_us",
+		.read_s64 = cpu_cfs_quota_read_s64,
+		.write_s64 = cpu_cfs_quota_write_s64,
+	},
+	{
+		.name = "cfs_period_us",
+		.read_u64 = cpu_cfs_period_read_u64,
+		.write_u64 = cpu_cfs_period_write_u64,
+	},
+	{
+		.name = "stat",
+		.seq_show = cpu_cfs_stat_show,
+	},
+#endif
+#ifdef CONFIG_RT_GROUP_SCHED
+	{
+		.name = "rt_runtime_us",
+		.read_s64 = cpu_rt_runtime_read,
+		.write_s64 = cpu_rt_runtime_write,
+	},
+	{
+		.name = "rt_period_us",
+		.read_u64 = cpu_rt_period_read_uint,
+		.write_u64 = cpu_rt_period_write_uint,
+	},
+#endif
+	{ }	/* Terminate */
+};
+
+static int cpu_extra_stat_show(struct seq_file *sf,
+			       struct cgroup_subsys_state *css)
+{
+#ifdef CONFIG_CFS_BANDWIDTH
+	{
+		struct task_group *tg = css_tg(css);
+		struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
+		u64 throttled_usec;
+
+		throttled_usec = cfs_b->throttled_time;
+		do_div(throttled_usec, NSEC_PER_USEC);
+
+		seq_printf(sf, "nr_periods %d\n"
+			   "nr_throttled %d\n"
+			   "throttled_usec %llu\n",
+			   cfs_b->nr_periods, cfs_b->nr_throttled,
+			   throttled_usec);
+	}
+#endif
+	return 0;
+}
+
+#ifdef CONFIG_FAIR_GROUP_SCHED
+static u64 cpu_weight_read_u64(struct cgroup_subsys_state *css,
+			       struct cftype *cft)
+{
+	struct task_group *tg = css_tg(css);
+	u64 weight = scale_load_down(tg->shares);
+
+	return DIV_ROUND_CLOSEST_ULL(weight * CGROUP_WEIGHT_DFL, 1024);
+}
+
+static int cpu_weight_write_u64(struct cgroup_subsys_state *css,
+				struct cftype *cft, u64 weight)
+{
+	/*
+	 * cgroup weight knobs should use the common MIN, DFL and MAX
+	 * values which are 1, 100 and 10000 respectively.  While it loses
+	 * a bit of range on both ends, it maps pretty well onto the shares
+	 * value used by scheduler and the round-trip conversions preserve
+	 * the original value over the entire range.
+	 */
+	if (weight < CGROUP_WEIGHT_MIN || weight > CGROUP_WEIGHT_MAX)
+		return -ERANGE;
+
+	weight = DIV_ROUND_CLOSEST_ULL(weight * 1024, CGROUP_WEIGHT_DFL);
+
+	return sched_group_set_shares(css_tg(css), scale_load(weight));
+}
+
+static s64 cpu_weight_nice_read_s64(struct cgroup_subsys_state *css,
+				    struct cftype *cft)
+{
+	unsigned long weight = scale_load_down(css_tg(css)->shares);
+	int last_delta = INT_MAX;
+	int prio, delta;
+
+	/* find the closest nice value to the current weight */
+	for (prio = 0; prio < ARRAY_SIZE(sched_prio_to_weight); prio++) {
+		delta = abs(sched_prio_to_weight[prio] - weight);
+		if (delta >= last_delta)
+			break;
+		last_delta = delta;
+	}
+
+	return PRIO_TO_NICE(prio - 1 + MAX_RT_PRIO);
+}
+
+static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css,
+				     struct cftype *cft, s64 nice)
+{
+	unsigned long weight;
+	int idx;
+
+	if (nice < MIN_NICE || nice > MAX_NICE)
+		return -ERANGE;
+
+	idx = NICE_TO_PRIO(nice) - MAX_RT_PRIO;
+	idx = array_index_nospec(idx, 40);
+	weight = sched_prio_to_weight[idx];
+
+	return sched_group_set_shares(css_tg(css), scale_load(weight));
+}
+#endif
+
+static void __maybe_unused cpu_period_quota_print(struct seq_file *sf,
+						  long period, long quota)
+{
+	if (quota < 0)
+		seq_puts(sf, "max");
+	else
+		seq_printf(sf, "%ld", quota);
+
+	seq_printf(sf, " %ld\n", period);
+}
+
+/* caller should put the current value in *@periodp before calling */
+static int __maybe_unused cpu_period_quota_parse(char *buf,
+						 u64 *periodp, u64 *quotap)
+{
+	char tok[21];	/* U64_MAX */
+
+	if (sscanf(buf, "%20s %llu", tok, periodp) < 1)
+		return -EINVAL;
+
+	*periodp *= NSEC_PER_USEC;
+
+	if (sscanf(tok, "%llu", quotap))
+		*quotap *= NSEC_PER_USEC;
+	else if (!strcmp(tok, "max"))
+		*quotap = RUNTIME_INF;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+#ifdef CONFIG_CFS_BANDWIDTH
+static int cpu_max_show(struct seq_file *sf, void *v)
+{
+	struct task_group *tg = css_tg(seq_css(sf));
+
+	cpu_period_quota_print(sf, tg_get_cfs_period(tg), tg_get_cfs_quota(tg));
+	return 0;
+}
+
+static ssize_t cpu_max_write(struct kernfs_open_file *of,
+			     char *buf, size_t nbytes, loff_t off)
+{
+	struct task_group *tg = css_tg(of_css(of));
+	u64 period = tg_get_cfs_period(tg);
+	u64 quota;
+	int ret;
+
+	ret = cpu_period_quota_parse(buf, &period, &quota);
+	if (!ret)
+		ret = tg_set_cfs_bandwidth(tg, period, quota);
+	return ret ?: nbytes;
+}
+#endif
+
+static struct cftype cpu_files[] = {
+#ifdef CONFIG_FAIR_GROUP_SCHED
+	{
+		.name = "weight",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.read_u64 = cpu_weight_read_u64,
+		.write_u64 = cpu_weight_write_u64,
+	},
+	{
+		.name = "weight.nice",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.read_s64 = cpu_weight_nice_read_s64,
+		.write_s64 = cpu_weight_nice_write_s64,
+	},
+#endif
+#ifdef CONFIG_CFS_BANDWIDTH
+	{
+		.name = "max",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = cpu_max_show,
+		.write = cpu_max_write,
+	},
+#endif
+	{ }	/* terminate */
+};
+
+struct cgroup_subsys cpu_cgrp_subsys = {
+	.css_alloc	= cpu_cgroup_css_alloc,
+	.css_online	= cpu_cgroup_css_online,
+	.css_released	= cpu_cgroup_css_released,
+	.css_free	= cpu_cgroup_css_free,
+	.css_extra_stat_show = cpu_extra_stat_show,
+	.fork		= cpu_cgroup_fork,
+	.can_attach	= cpu_cgroup_can_attach,
+	.attach		= cpu_cgroup_attach,
+	.legacy_cftypes	= cpu_legacy_files,
+	.dfl_cftypes	= cpu_files,
+	.early_init	= true,
+	.threaded	= true,
+};
+
+#endif	/* CONFIG_CGROUP_SCHED */
+
+void dump_cpu_task(int cpu)
+{
+	pr_info("Task dump for CPU %d:\n", cpu);
+	sched_show_task(cpu_curr(cpu));
+}
+
+/*
+ * Nice levels are multiplicative, with a gentle 10% change for every
+ * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
+ * nice 1, it will get ~10% less CPU time than another CPU-bound task
+ * that remained on nice 0.
+ *
+ * The "10% effect" is relative and cumulative: from _any_ nice level,
+ * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
+ * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
+ * If a task goes up by ~10% and another task goes down by ~10% then
+ * the relative distance between them is ~25%.)
+ */
+const int sched_prio_to_weight[40] = {
+ /* -20 */     88761,     71755,     56483,     46273,     36291,
+ /* -15 */     29154,     23254,     18705,     14949,     11916,
+ /* -10 */      9548,      7620,      6100,      4904,      3906,
+ /*  -5 */      3121,      2501,      1991,      1586,      1277,
+ /*   0 */      1024,       820,       655,       526,       423,
+ /*   5 */       335,       272,       215,       172,       137,
+ /*  10 */       110,        87,        70,        56,        45,
+ /*  15 */        36,        29,        23,        18,        15,
+};
+
+/*
+ * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
+ *
+ * In cases where the weight does not change often, we can use the
+ * precalculated inverse to speed up arithmetics by turning divisions
+ * into multiplications:
+ */
+const u32 sched_prio_to_wmult[40] = {
+ /* -20 */     48388,     59856,     76040,     92818,    118348,
+ /* -15 */    147320,    184698,    229616,    287308,    360437,
+ /* -10 */    449829,    563644,    704093,    875809,   1099582,
+ /*  -5 */   1376151,   1717300,   2157191,   2708050,   3363326,
+ /*   0 */   4194304,   5237765,   6557202,   8165337,  10153587,
+ /*   5 */  12820798,  15790321,  19976592,  24970740,  31350126,
+ /*  10 */  39045157,  49367440,  61356676,  76695844,  95443717,
+ /*  15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
+};
+
+#undef CREATE_TRACE_POINTS