diff options
| -rw-r--r-- | kernel/sched/core.c | 33 |
1 files changed, 28 insertions, 5 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c1ba2e569fc9..60791b991b21 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2293,8 +2293,15 @@ void sched_ttwu_pending(void *arg) rq_lock_irqsave(rq, &rf); update_rq_clock(rq); - llist_for_each_entry_safe(p, t, llist, wake_entry) + llist_for_each_entry_safe(p, t, llist, wake_entry) { + if (WARN_ON_ONCE(p->on_cpu)) + smp_cond_load_acquire(&p->on_cpu, !VAL); + + if (WARN_ON_ONCE(task_cpu(p) != cpu_of(rq))) + set_task_cpu(p, cpu_of(rq)); + ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf); + } rq_unlock_irqrestore(rq, &rf); } @@ -2378,6 +2385,9 @@ static inline bool ttwu_queue_cond(int cpu, int wake_flags) static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags) { if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu, wake_flags)) { + if (WARN_ON_ONCE(cpu == smp_processor_id())) + return false; + sched_clock_cpu(cpu); /* Sync clocks across CPUs */ __ttwu_queue_wakelist(p, cpu, wake_flags); return true; @@ -2528,7 +2538,6 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) goto out; success = 1; - cpu = task_cpu(p); trace_sched_waking(p); p->state = TASK_RUNNING; trace_sched_wakeup(p); @@ -2550,7 +2559,6 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) /* We're going to change ->state: */ success = 1; - cpu = task_cpu(p); /* * Ensure we load p->on_rq _after_ p->state, otherwise it would @@ -2614,8 +2622,21 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) * which potentially sends an IPI instead of spinning on p->on_cpu to * let the waker make forward progress. This is safe because IRQs are * disabled and the IPI will deliver after on_cpu is cleared. + * + * Ensure we load task_cpu(p) after p->on_cpu: + * + * set_task_cpu(p, cpu); + * STORE p->cpu = @cpu + * __schedule() (switch to task 'p') + * LOCK rq->lock + * smp_mb__after_spin_lock() smp_cond_load_acquire(&p->on_cpu) + * STORE p->on_cpu = 1 LOAD p->cpu + * + * to ensure we observe the correct CPU on which the task is currently + * scheduling. */ - if (READ_ONCE(p->on_cpu) && ttwu_queue_wakelist(p, cpu, wake_flags | WF_ON_RQ)) + if (smp_load_acquire(&p->on_cpu) && + ttwu_queue_wakelist(p, task_cpu(p), wake_flags | WF_ON_RQ)) goto unlock; /* @@ -2635,6 +2656,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) psi_ttwu_dequeue(p); set_task_cpu(p, cpu); } +#else + cpu = task_cpu(p); #endif /* CONFIG_SMP */ ttwu_queue(p, cpu, wake_flags); @@ -2642,7 +2665,7 @@ unlock: raw_spin_unlock_irqrestore(&p->pi_lock, flags); out: if (success) - ttwu_stat(p, cpu, wake_flags); + ttwu_stat(p, task_cpu(p), wake_flags); preempt_enable(); return success; |