Merge tag 'sched-urgent-2022-08-06' of git://git.kernel.org/pub/scm/l…

…inux/kernel/git/tip/tip

Pull scheduler fixes from Ingo Molnar:
 "Various fixes: a deadline scheduler fix, a migration fix, a Sparse fix
  and a comment fix"

* tag 'sched-urgent-2022-08-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Do not requeue task on CPU excluded from cpus_mask
  sched/rt: Fix Sparse warnings due to undefined rt.c declarations
  exit: Fix typo in comment: s/sub-theads/sub-threads
  sched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed

include/linux/sched.h

@@ -1825,7 +1825,7 @@ current_restore_flags(unsigned long orig_flags, unsigned long flags)
 }
 
 extern int cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct cpumask *trial);
-extern int task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed);
+extern int task_can_attach(struct task_struct *p, const struct cpumask *cs_effective_cpus);
 #ifdef CONFIG_SMP
 extern void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask);
 extern int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask);

kernel/cgroup/cpuset.c

@@ -2239,7 +2239,7 @@ static int cpuset_can_attach(struct cgroup_taskset *tset)
 		goto out_unlock;
 
 	cgroup_taskset_for_each(task, css, tset) {
-		ret = task_can_attach(task, cs->cpus_allowed);
+		ret = task_can_attach(task, cs->effective_cpus);
 		if (ret)
 			goto out_unlock;
 		ret = security_task_setscheduler(task);

kernel/exit.c

@@ -1051,7 +1051,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 		 * p->signal fields because the whole thread group is dead
 		 * and nobody can change them.
 		 *
-		 * psig->stats_lock also protects us from our sub-theads
+		 * psig->stats_lock also protects us from our sub-threads
 		 * which can reap other children at the same time. Until
 		 * we change k_getrusage()-like users to rely on this lock
 		 * we have to take ->siglock as well.

kernel/sched/core.c

@@ -3802,7 +3802,7 @@ bool cpus_share_cache(int this_cpu, int that_cpu)
 	return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
 }
 
-static inline bool ttwu_queue_cond(int cpu)
+static inline bool ttwu_queue_cond(struct task_struct *p, int cpu)
 {
 	/*
 	 * Do not complicate things with the async wake_list while the CPU is
@@ -3811,6 +3811,10 @@ static inline bool ttwu_queue_cond(int cpu)
 	if (!cpu_active(cpu))
 		return false;
 
+	/* Ensure the task will still be allowed to run on the CPU. */
+	if (!cpumask_test_cpu(cpu, p->cpus_ptr))
+		return false;
+
 	/*
 	 * If the CPU does not share cache, then queue the task on the
 	 * remote rqs wakelist to avoid accessing remote data.
@@ -3840,7 +3844,7 @@ static inline bool ttwu_queue_cond(int cpu)
 
 static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
 {
-	if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu)) {
+	if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(p, cpu)) {
 		sched_clock_cpu(cpu); /* Sync clocks across CPUs */
 		__ttwu_queue_wakelist(p, cpu, wake_flags);
 		return true;
@@ -9012,7 +9016,7 @@ int cpuset_cpumask_can_shrink(const struct cpumask *cur,
 }
 
 int task_can_attach(struct task_struct *p,
-		    const struct cpumask *cs_cpus_allowed)
+		    const struct cpumask *cs_effective_cpus)
 {
 	int ret = 0;
 
@@ -9031,9 +9035,11 @@ int task_can_attach(struct task_struct *p,
 	}
 
 	if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
-					      cs_cpus_allowed)) {
-		int cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed);
+					      cs_effective_cpus)) {
+		int cpu = cpumask_any_and(cpu_active_mask, cs_effective_cpus);
 
+		if (unlikely(cpu >= nr_cpu_ids))
+			return -EINVAL;
 		ret = dl_cpu_busy(cpu, p);
 	}
 

kernel/sched/sched.h

@@ -481,9 +481,6 @@ extern void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b);
 extern void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b);
 extern void unthrottle_cfs_rq(struct cfs_rq *cfs_rq);
 
-extern void unregister_rt_sched_group(struct task_group *tg);
-extern void free_rt_sched_group(struct task_group *tg);
-extern int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent);
 extern void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
 		struct sched_rt_entity *rt_se, int cpu,
 		struct sched_rt_entity *parent);
@@ -521,6 +518,10 @@ struct cfs_bandwidth { };
 
 #endif	/* CONFIG_CGROUP_SCHED */
 
+extern void unregister_rt_sched_group(struct task_group *tg);
+extern void free_rt_sched_group(struct task_group *tg);
+extern int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent);
+
 /*
  * u64_u32_load/u64_u32_store
  *