Merge: Sched: Post 6.12 updates and fixes

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/88

JIRA: https://issues.redhat.com/browse/RHEL-70901

Several fixes have landed post-v6.12. Pull them in for 10.0 GA
to prevent hitting issues later.

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

Approved-by: Juri Lelli <juri.lelli@redhat.com>
Approved-by: Waiman Long <longman@redhat.com>
Approved-by: Rafael Aquini <raquini@redhat.com>
Approved-by: David Arcari <darcari@redhat.com>
Approved-by: Lenny Szubowicz <lszubowi@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Jan Stancek <jstancek@redhat.com>

Author: jstancek

arch/x86/kernel/cpu/topology.c

@@ -428,8 +428,8 @@ void __init topology_apply_cmdline_limits_early(void)
 {
 	unsigned int possible = nr_cpu_ids;
 
-	/* 'maxcpus=0' 'nosmp' 'nolapic' 'disableapic' 'noapic' */
-	if (!setup_max_cpus || ioapic_is_disabled || apic_is_disabled)
+	/* 'maxcpus=0' 'nosmp' 'nolapic' 'disableapic' */
+	if (!setup_max_cpus || apic_is_disabled)
 		possible = 1;
 
 	/* 'possible_cpus=N' */
@@ -443,7 +443,7 @@ void __init topology_apply_cmdline_limits_early(void)
 
 static __init bool restrict_to_up(void)
 {
-	if (!smp_found_config || ioapic_is_disabled)
+	if (!smp_found_config)
 		return true;
 	/*
 	 * XEN PV is special as it does not advertise the local APIC

kernel/sched/core.c

@@ -1288,9 +1288,9 @@ static void nohz_csd_func(void *info)
 	WARN_ON(!(flags & NOHZ_KICK_MASK));
 
 	rq->idle_balance = idle_cpu(cpu);
-	if (rq->idle_balance && !need_resched()) {
+	if (rq->idle_balance) {
 		rq->nohz_idle_balance = flags;
-		raise_softirq_irqoff(SCHED_SOFTIRQ);
+		__raise_softirq_irqoff(SCHED_SOFTIRQ);
 	}
 }
 

kernel/sched/deadline.c

@@ -781,7 +781,7 @@ static inline void replenish_dl_new_period(struct sched_dl_entity *dl_se,
 	 * If it is a deferred reservation, and the server
 	 * is not handling an starvation case, defer it.
 	 */
-	if (dl_se->dl_defer & !dl_se->dl_defer_running) {
+	if (dl_se->dl_defer && !dl_se->dl_defer_running) {
 		dl_se->dl_throttled = 1;
 		dl_se->dl_defer_armed = 1;
 	}
@@ -2042,6 +2042,7 @@ enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags)
 	} else if (flags & ENQUEUE_REPLENISH) {
 		replenish_dl_entity(dl_se);
 	} else if ((flags & ENQUEUE_RESTORE) &&
+		   !is_dl_boosted(dl_se) &&
 		   dl_time_before(dl_se->deadline, rq_clock(rq_of_dl_se(dl_se)))) {
 		setup_new_dl_entity(dl_se);
 	}

kernel/sched/fair.c

@@ -12574,7 +12574,7 @@ static void _nohz_idle_balance(struct rq *this_rq, unsigned int flags)
 		 * work being done for other CPUs. Next load
 		 * balancing owner will pick it up.
 		 */
-		if (need_resched()) {
+		if (!idle_cpu(this_cpu) && need_resched()) {
 			if (flags & NOHZ_STATS_KICK)
 				has_blocked_load = true;
 			if (flags & NOHZ_NEXT_KICK)

kernel/sched/syscalls.c

@@ -1238,7 +1238,7 @@ int __sched_setaffinity(struct task_struct *p, struct affinity_context *ctx)
 			bool empty = !cpumask_and(new_mask, new_mask,
 						  ctx->user_mask);
 
-			if (WARN_ON_ONCE(empty))
+			if (empty)
 				cpumask_copy(new_mask, cpus_allowed);
 		}
 		__set_cpus_allowed_ptr(p, ctx);

kernel/softirq.c

@@ -280,17 +280,24 @@ static inline void invoke_softirq(void)
 		wakeup_softirqd();
 }
 
+#define SCHED_SOFTIRQ_MASK	BIT(SCHED_SOFTIRQ)
+
 /*
  * flush_smp_call_function_queue() can raise a soft interrupt in a function
- * call. On RT kernels this is undesired and the only known functionality
- * in the block layer which does this is disabled on RT. If soft interrupts
- * get raised which haven't been raised before the flush, warn so it can be
+ * call. On RT kernels this is undesired and the only known functionalities
+ * are in the block layer which is disabled on RT, and in the scheduler for
+ * idle load balancing. If soft interrupts get raised which haven't been
+ * raised before the flush, warn if it is not a SCHED_SOFTIRQ so it can be
  * investigated.
  */
 void do_softirq_post_smp_call_flush(unsigned int was_pending)
 {
-	if (WARN_ON_ONCE(was_pending != local_softirq_pending()))
+	unsigned int is_pending = local_softirq_pending();
+
+	if (unlikely(was_pending != is_pending)) {
+		WARN_ON_ONCE(was_pending != (is_pending & ~SCHED_SOFTIRQ_MASK));
 		invoke_softirq();
+	}
 }
 
 #else /* CONFIG_PREEMPT_RT */