Merge: sched: Fix migrate_swap() vs. hotplug

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/7236

JIRA: https://issues.redhat.com/browse/RHEL-107437

Two fixes from upstream are needed for commits we have in
the rhel9 tree.

Signed-off-by: Phil Auld <pauld@redhat.com>

Approved-by: Herton R. Krzesinski <herton@redhat.com>
Approved-by: Waiman Long <longman@redhat.com>
Approved-by: Juri Lelli <juri.lelli@redhat.com>
Approved-by: Rafael Aquini <raquini@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Jarod Wilson <jarod@redhat.com>

Author: jarodwilson

kernel/sched/core.c

@@ -3830,6 +3830,11 @@ bool cpus_share_resources(int this_cpu, int that_cpu)
 
 static inline bool ttwu_queue_cond(struct task_struct *p, int cpu)
 {
+#ifdef CONFIG_SMP
+	if (p->sched_class == &stop_sched_class)
+		return false;
+#endif
+
 	/*
 	 * Do not complicate things with the async wake_list while the CPU is
 	 * in hotplug state.

kernel/sched/loadavg.c

@@ -80,7 +80,7 @@ long calc_load_fold_active(struct rq *this_rq, long adjust)
 	long nr_active, delta = 0;
 
 	nr_active = this_rq->nr_running - adjust;
-	nr_active += (int)this_rq->nr_uninterruptible;
+	nr_active += (long)this_rq->nr_uninterruptible;
 
 	if (nr_active != this_rq->calc_load_active) {
 		delta = nr_active - this_rq->calc_load_active;

kernel/sched/sched.h

@@ -1079,7 +1079,7 @@ struct rq {
 	 * one CPU and if it got migrated afterwards it may decrease
 	 * it on another CPU. Always updated under the runqueue lock:
 	 */
-	unsigned int		nr_uninterruptible;
+	unsigned long 		nr_uninterruptible;
 
 	struct task_struct __rcu	*curr;
 	struct task_struct	*idle;

kernel/stop_machine.c

@@ -82,31 +82,29 @@ static void cpu_stop_signal_done(struct cpu_stop_done *done)
 }
 
 static void __cpu_stop_queue_work(struct cpu_stopper *stopper,
-					struct cpu_stop_work *work,
-					struct wake_q_head *wakeq)
+				  struct cpu_stop_work *work)
 {
 	list_add_tail(&work->list, &stopper->works);
-	wake_q_add(wakeq, stopper->thread);
 }
 
 /* queue @work to @stopper.  if offline, @work is completed immediately */
 static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
 {
 	struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
-	DEFINE_WAKE_Q(wakeq);
 	unsigned long flags;
 	bool enabled;
 
 	preempt_disable();
 	raw_spin_lock_irqsave(&stopper->lock, flags);
 	enabled = stopper->enabled;
 	if (enabled)
-		__cpu_stop_queue_work(stopper, work, &wakeq);
+		__cpu_stop_queue_work(stopper, work);
 	else if (work->done)
 		cpu_stop_signal_done(work->done);
 	raw_spin_unlock_irqrestore(&stopper->lock, flags);
 
-	wake_up_q(&wakeq);
+	if (enabled)
+		wake_up_process(stopper->thread);
 	preempt_enable();
 
 	return enabled;
@@ -263,7 +261,6 @@ static int cpu_stop_queue_two_works(int cpu1, struct cpu_stop_work *work1,
 {
 	struct cpu_stopper *stopper1 = per_cpu_ptr(&cpu_stopper, cpu1);
 	struct cpu_stopper *stopper2 = per_cpu_ptr(&cpu_stopper, cpu2);
-	DEFINE_WAKE_Q(wakeq);
 	int err;
 
 retry:
@@ -299,8 +296,8 @@ static int cpu_stop_queue_two_works(int cpu1, struct cpu_stop_work *work1,
 	}
 
 	err = 0;
-	__cpu_stop_queue_work(stopper1, work1, &wakeq);
-	__cpu_stop_queue_work(stopper2, work2, &wakeq);
+	__cpu_stop_queue_work(stopper1, work1);
+	__cpu_stop_queue_work(stopper2, work2);
 
 unlock:
 	raw_spin_unlock(&stopper2->lock);
@@ -315,7 +312,10 @@ static int cpu_stop_queue_two_works(int cpu1, struct cpu_stop_work *work1,
 		goto retry;
 	}
 
-	wake_up_q(&wakeq);
+	if (!err) {
+		wake_up_process(stopper1->thread);
+		wake_up_process(stopper2->thread);
+	}
 	preempt_enable();
 
 	return err;