The alleged requirement that the migration notifier has a lower priority than perf is completely undocumented and there is no indication at all that this is true. perf does not even handle the CPU_ONLINE notification and perf really has nothing to do with migration. Move the CPU_ONLINE code into the sched_activate_cpu() state callback. Signed-off-by: Thomas Gleixner --- kernel/sched/core.c | 33 ++++++++++++++++++++++----------- 1 file changed, 22 insertions(+), 11 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5662,17 +5662,6 @@ migration_call(struct notifier_block *nf switch (action & ~CPU_TASKS_FROZEN) { - case CPU_ONLINE: - /* Update our root-domain */ - raw_spin_lock_irqsave(&rq->lock, flags); - if (rq->rd) { - BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); - - set_rq_online(rq); - } - raw_spin_unlock_irqrestore(&rq->lock, flags); - break; - #ifdef CONFIG_HOTPLUG_CPU case CPU_DYING: sched_ttwu_pending(); @@ -7323,12 +7312,34 @@ static int cpuset_cpu_inactive(unsigned int sched_cpu_activate(unsigned int cpu) { + struct rq *rq = cpu_rq(cpu); + unsigned long flags; + 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. + */ + raw_spin_lock_irqsave(&rq->lock, flags); + if (rq->rd) { + BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); + set_rq_online(rq); + } + raw_spin_unlock_irqrestore(&rq->lock, flags); + + update_max_interval(); + return 0; }