diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index fa87b6a15082c..463a5dfbbcb0b 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -29,8 +29,6 @@
 
 struct kernel_clone_args;
 
-#ifdef CONFIG_CGROUPS
-
 /*
  * All weight knobs on the default hierarchy should use the following min,
  * default and max values.  The default value is the logarithmic center of
@@ -40,13 +38,13 @@ struct kernel_clone_args;
 #define CGROUP_WEIGHT_DFL		100
 #define CGROUP_WEIGHT_MAX		10000
 
-/* walk only threadgroup leaders */
-#define CSS_TASK_ITER_PROCS		(1U << 0)
-/* walk all threaded css_sets in the domain */
-#define CSS_TASK_ITER_THREADED		(1U << 1)
+#ifdef CONFIG_CGROUPS
 
-/* internal flags */
-#define CSS_TASK_ITER_SKIPPED		(1U << 16)
+enum {
+	CSS_TASK_ITER_PROCS    = (1U << 0),  /* walk only threadgroup leaders */
+	CSS_TASK_ITER_THREADED = (1U << 1),  /* walk all threaded css_sets in the domain */
+	CSS_TASK_ITER_SKIPPED  = (1U << 16), /* internal flags */
+};
 
 /* a css_task_iter should be treated as an opaque object */
 struct css_task_iter {
diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index 1f378f7dd1d39..f31c69c1e1693 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -64,7 +64,8 @@ extern asmlinkage void schedule_tail(struct task_struct *prev);
 extern void init_idle(struct task_struct *idle, int cpu);
 
 extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
-extern void sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs);
+extern int sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs);
+extern void sched_cancel_fork(struct task_struct *p);
 extern void sched_post_fork(struct task_struct *p);
 extern void sched_dead(struct task_struct *p);
 
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index e15d366c164bd..51c7fabba135b 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4950,9 +4950,11 @@ static void css_task_iter_advance(struct css_task_iter *it)
 void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
 			 struct css_task_iter *it)
 {
+	unsigned long irqflags;
+
 	memset(it, 0, sizeof(*it));
 
-	spin_lock_irq(&css_set_lock);
+	spin_lock_irqsave(&css_set_lock, irqflags);
 
 	it->ss = css->ss;
 	it->flags = flags;
@@ -4966,7 +4968,7 @@ void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
 
 	css_task_iter_advance(it);
 
-	spin_unlock_irq(&css_set_lock);
+	spin_unlock_irqrestore(&css_set_lock, irqflags);
 }
 
 /**
@@ -4979,12 +4981,14 @@ void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
  */
 struct task_struct *css_task_iter_next(struct css_task_iter *it)
 {
+	unsigned long irqflags;
+
 	if (it->cur_task) {
 		put_task_struct(it->cur_task);
 		it->cur_task = NULL;
 	}
 
-	spin_lock_irq(&css_set_lock);
+	spin_lock_irqsave(&css_set_lock, irqflags);
 
 	/* @it may be half-advanced by skips, finish advancing */
 	if (it->flags & CSS_TASK_ITER_SKIPPED)
@@ -4997,7 +5001,7 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it)
 		css_task_iter_advance(it);
 	}
 
-	spin_unlock_irq(&css_set_lock);
+	spin_unlock_irqrestore(&css_set_lock, irqflags);
 
 	return it->cur_task;
 }
@@ -5010,11 +5014,13 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it)
  */
 void css_task_iter_end(struct css_task_iter *it)
 {
+	unsigned long irqflags;
+
 	if (it->cur_cset) {
-		spin_lock_irq(&css_set_lock);
+		spin_lock_irqsave(&css_set_lock, irqflags);
 		list_del(&it->iters_node);
 		put_css_set_locked(it->cur_cset);
-		spin_unlock_irq(&css_set_lock);
+		spin_unlock_irqrestore(&css_set_lock, irqflags);
 	}
 
 	if (it->cur_dcset)
diff --git a/kernel/fork.c b/kernel/fork.c
index 9b96d6e7cf958..8bff0c02cd618 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2557,7 +2557,7 @@ __latent_entropy struct task_struct *copy_process(
 
 	retval = perf_event_init_task(p, clone_flags);
 	if (retval)
-		goto bad_fork_cleanup_policy;
+		goto bad_fork_sched_cancel_fork;
 	retval = audit_alloc(p);
 	if (retval)
 		goto bad_fork_cleanup_perf;
@@ -2689,7 +2689,9 @@ __latent_entropy struct task_struct *copy_process(
 	 * cgroup specific, it unconditionally needs to place the task on a
 	 * runqueue.
 	 */
-	sched_cgroup_fork(p, args);
+	retval = sched_cgroup_fork(p, args);
+	if (retval)
+		goto bad_fork_cancel_cgroup;
 
 	/*
 	 * From this point on we must avoid any synchronous user-space
@@ -2735,13 +2737,13 @@ __latent_entropy struct task_struct *copy_process(
 	/* Don't start children in a dying pid namespace */
 	if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
 		retval = -ENOMEM;
-		goto bad_fork_cancel_cgroup;
+		goto bad_fork_core_free;
 	}
 
 	/* Let kill terminate clone/fork in the middle */
 	if (fatal_signal_pending(current)) {
 		retval = -EINTR;
-		goto bad_fork_cancel_cgroup;
+		goto bad_fork_core_free;
 	}
 
 	/* No more failure paths after this point. */
@@ -2815,10 +2817,11 @@ __latent_entropy struct task_struct *copy_process(
 
 	return p;
 
-bad_fork_cancel_cgroup:
+bad_fork_core_free:
 	sched_core_free(p);
 	spin_unlock(&current->sighand->siglock);
 	write_unlock_irq(&tasklist_lock);
+bad_fork_cancel_cgroup:
 	cgroup_cancel_fork(p, args);
 bad_fork_put_pidfd:
 	if (clone_flags & CLONE_PIDFD) {
@@ -2857,6 +2860,8 @@ __latent_entropy struct task_struct *copy_process(
 	audit_free(p);
 bad_fork_cleanup_perf:
 	perf_event_free_task(p);
+bad_fork_sched_cancel_fork:
+	sched_cancel_fork(p);
 bad_fork_cleanup_policy:
 	lockdep_free_task(p);
 #ifdef CONFIG_NUMA
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ae4ce9069ce38..7b55573b0aa16 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1341,8 +1341,8 @@ void set_load_weight(struct task_struct *p, bool update_load)
 	 * SCHED_OTHER tasks have to update their load when changing their
 	 * weight
 	 */
-	if (update_load && p->sched_class == &fair_sched_class)
-		reweight_task(p, &lw);
+	if (update_load && p->sched_class->reweight_task)
+		p->sched_class->reweight_task(task_rq(p), p, &lw);
 	else
 		p->se.load = lw;
 }
@@ -2064,6 +2064,17 @@ inline int task_curr(const struct task_struct *p)
 	return cpu_curr(task_cpu(p)) == p;
 }
 
+/*
+ * ->switching_to() is called with the pi_lock and rq_lock held and must not
+ * mess with locking.
+ */
+void check_class_changing(struct rq *rq, struct task_struct *p,
+			  const struct sched_class *prev_class)
+{
+	if (prev_class != p->sched_class && p->sched_class->switching_to)
+		p->sched_class->switching_to(rq, p);
+}
+
 /*
  * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
  * use the balance_callback list if you want balancing.
@@ -4648,7 +4659,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
 	return 0;
 }
 
-void sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs)
+int sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs)
 {
 	unsigned long flags;
 
@@ -4675,6 +4686,12 @@ void sched_cgroup_fork(struct task_struct *p, struct kernel_clone_args *kargs)
 	if (p->sched_class->task_fork)
 		p->sched_class->task_fork(p);
 	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+
+	return 0;
+}
+
+void sched_cancel_fork(struct task_struct *p)
+{
 }
 
 void sched_post_fork(struct task_struct *p)
@@ -7128,6 +7145,7 @@ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
 
 	p->sched_class = next_class;
 	p->prio = prio;
+	check_class_changing(rq, p, prev_class);
 
 	if (queued)
 		enqueue_task(rq, p, queue_flag);
@@ -8301,12 +8319,12 @@ void __init sched_init(void)
 	int i;
 
 	/* Make sure the linker didn't screw up */
-	BUG_ON(&idle_sched_class != &fair_sched_class + 1 ||
-	       &fair_sched_class != &rt_sched_class + 1 ||
-	       &rt_sched_class   != &dl_sched_class + 1);
 #ifdef CONFIG_SMP
-	BUG_ON(&dl_sched_class != &stop_sched_class + 1);
+	BUG_ON(!sched_class_above(&stop_sched_class, &dl_sched_class));
 #endif
+	BUG_ON(!sched_class_above(&dl_sched_class, &rt_sched_class));
+	BUG_ON(!sched_class_above(&rt_sched_class, &fair_sched_class));
+	BUG_ON(!sched_class_above(&fair_sched_class, &idle_sched_class));
 
 	wait_bit_init();
 
@@ -9681,29 +9699,27 @@ static int cpu_local_stat_show(struct seq_file *sf,
 }
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
+
+static unsigned long tg_weight(struct task_group *tg)
+{
+	return scale_load_down(tg->shares);
+}
+
 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);
+	return sched_weight_to_cgroup(tg_weight(css_tg(css)));
 }
 
 static int cpu_weight_write_u64(struct cgroup_subsys_state *css,
-				struct cftype *cft, u64 weight)
+				struct cftype *cft, u64 cgrp_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)
+	unsigned long weight;
+
+	if (cgrp_weight < CGROUP_WEIGHT_MIN || cgrp_weight > CGROUP_WEIGHT_MAX)
 		return -ERANGE;
 
-	weight = DIV_ROUND_CLOSEST_ULL(weight * 1024, CGROUP_WEIGHT_DFL);
+	weight = sched_weight_from_cgroup(cgrp_weight);
 
 	return sched_group_set_shares(css_tg(css), scale_load(weight));
 }
@@ -9711,7 +9727,7 @@ static int cpu_weight_write_u64(struct cgroup_subsys_state *css,
 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);
+	unsigned long weight = tg_weight(css_tg(css));
 	int last_delta = INT_MAX;
 	int prio, delta;
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1d747f6bc9140..410ceba73a247 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3958,7 +3958,7 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
 	}
 }
 
-void reweight_task(struct task_struct *p, const struct load_weight *lw)
+static void reweight_task_fair(struct rq *this_rq, struct task_struct *p, const struct load_weight *lw)
 {
 	struct sched_entity *se = &p->se;
 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
@@ -8692,7 +8692,7 @@ static void check_preempt_wakeup_fair(struct rq *rq, struct task_struct *p, int
 	/*
 	 * BATCH and IDLE tasks do not preempt others.
 	 */
-	if (unlikely(p->policy != SCHED_NORMAL))
+	if (unlikely(!normal_policy(p->policy)))
 		return;
 
 	cfs_rq = cfs_rq_of(se);
@@ -9649,28 +9649,18 @@ static inline void update_blocked_load_status(struct rq *rq, bool has_blocked) {
 
 static bool __update_blocked_others(struct rq *rq, bool *done)
 {
-	const struct sched_class *curr_class;
-	u64 now = rq_clock_pelt(rq);
-	unsigned long thermal_pressure;
-	bool decayed;
+	bool updated;
 
 	/*
 	 * update_load_avg() can call cpufreq_update_util(). Make sure that RT,
 	 * DL and IRQ signals have been updated before updating CFS.
 	 */
-	curr_class = rq->curr->sched_class;
-
-	thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
-
-	decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |
-		  update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |
-		  update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure) |
-		  update_irq_load_avg(rq, 0);
+	updated = update_other_load_avgs(rq);
 
 	if (others_have_blocked(rq))
 		*done = false;
 
-	return decayed;
+	return updated;
 }
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
@@ -13551,6 +13541,7 @@ DEFINE_SCHED_CLASS(fair) = {
 	.task_tick		= task_tick_fair,
 	.task_fork		= task_fork_fair,
 
+	.reweight_task		= reweight_task_fair,
 	.prio_changed		= prio_changed_fair,
 	.switched_from		= switched_from_fair,
 	.switched_to		= switched_to_fair,
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index f46c648e5a85c..caef5ccaae959 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -189,9 +189,14 @@ static inline int idle_policy(int policy)
 	return policy == SCHED_IDLE;
 }
 
+static inline int normal_policy(int policy)
+{
+	return policy == SCHED_NORMAL;
+}
+
 static inline int fair_policy(int policy)
 {
-	return policy == SCHED_NORMAL || policy == SCHED_BATCH;
+	return normal_policy(policy) || policy == SCHED_BATCH;
 }
 
 static inline int rt_policy(int policy)
@@ -241,6 +246,24 @@ static inline void update_avg(u64 *avg, u64 sample)
 #define shr_bound(val, shift)							\
 	(val >> min_t(typeof(shift), shift, BITS_PER_TYPE(typeof(val)) - 1))
 
+/*
+ * 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.
+ */
+static inline unsigned long sched_weight_from_cgroup(unsigned long cgrp_weight)
+{
+	return DIV_ROUND_CLOSEST_ULL(cgrp_weight * 1024, CGROUP_WEIGHT_DFL);
+}
+
+static inline unsigned long sched_weight_to_cgroup(unsigned long weight)
+{
+	return clamp_t(unsigned long,
+		       DIV_ROUND_CLOSEST_ULL(weight * CGROUP_WEIGHT_DFL, 1024),
+		       CGROUP_WEIGHT_MIN, CGROUP_WEIGHT_MAX);
+}
+
 /*
  * !! For sched_setattr_nocheck() (kernel) only !!
  *
@@ -2365,8 +2388,11 @@ struct sched_class {
 	 * cannot assume the switched_from/switched_to pair is serialized by
 	 * rq->lock. They are however serialized by p->pi_lock.
 	 */
+	void (*switching_to) (struct rq *this_rq, struct task_struct *task);
 	void (*switched_from)(struct rq *this_rq, struct task_struct *task);
 	void (*switched_to)  (struct rq *this_rq, struct task_struct *task);
+	void (*reweight_task)(struct rq *this_rq, struct task_struct *task,
+			      const struct load_weight *lw);
 	void (*prio_changed) (struct rq *this_rq, struct task_struct *task,
 			      int oldprio);
 
@@ -2554,8 +2580,6 @@ extern void init_sched_dl_class(void);
 extern void init_sched_rt_class(void);
 extern void init_sched_fair_class(void);
 
-extern void reweight_task(struct task_struct *p, const struct load_weight *lw);
-
 extern void resched_curr(struct rq *rq);
 extern void resched_cpu(int cpu);
 
@@ -3173,6 +3197,8 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) { }
 
 #ifdef CONFIG_SMP
 
+bool update_other_load_avgs(struct rq *rq);
+
 unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
 				 unsigned long *min,
 				 unsigned long *max);
@@ -3216,6 +3242,8 @@ static inline unsigned long cpu_util_rt(struct rq *rq)
 	return READ_ONCE(rq->avg_rt.util_avg);
 }
 
+#else /* !CONFIG_SMP */
+static inline bool update_other_load_avgs(struct rq *rq) { return false; }
 #endif /* CONFIG_SMP */
 
 #ifdef CONFIG_UCLAMP_TASK
@@ -3782,6 +3810,8 @@ extern void set_load_weight(struct task_struct *p, bool update_load);
 extern void enqueue_task(struct rq *rq, struct task_struct *p, int flags);
 extern bool dequeue_task(struct rq *rq, struct task_struct *p, int flags);
 
+extern void check_class_changing(struct rq *rq, struct task_struct *p,
+				 const struct sched_class *prev_class);
 extern void check_class_changed(struct rq *rq, struct task_struct *p,
 				const struct sched_class *prev_class,
 				int oldprio);
diff --git a/kernel/sched/syscalls.c b/kernel/sched/syscalls.c
index 7f92ae92a1c80..4de3a61839c0e 100644
--- a/kernel/sched/syscalls.c
+++ b/kernel/sched/syscalls.c
@@ -260,6 +260,25 @@ int sched_core_idle_cpu(int cpu)
 #endif
 
 #ifdef CONFIG_SMP
+/*
+ * Load avg and utiliztion metrics need to be updated periodically and before
+ * consumption. This function updates the metrics for all subsystems except for
+ * the fair class. @rq must be locked and have its clock updated.
+ */
+bool update_other_load_avgs(struct rq *rq)
+{
+	u64 now = rq_clock_pelt(rq);
+	const struct sched_class *curr_class = rq->curr->sched_class;
+	unsigned long thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
+
+	lockdep_assert_rq_held(rq);
+
+	return update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |
+		update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |
+		update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure) |
+		update_irq_load_avg(rq, 0);
+}
+
 /*
  * This function computes an effective utilization for the given CPU, to be
  * used for frequency selection given the linear relation: f = u * f_max.
@@ -823,6 +842,7 @@ int __sched_setscheduler(struct task_struct *p,
 		p->prio = newprio;
 	}
 	__setscheduler_uclamp(p, attr);
+	check_class_changing(rq, p, prev_class);
 
 	if (queued) {
 		/*