X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=kernel%2Fsched.c;h=3f2e502d609bb7957e10b4ec6aa647c9b3069c6e;hb=28f65c11f2ffb3957259dece647a24f8ad2e241b;hp=2d12893b8b0f0788dacb310f988cefd7d6d15440;hpb=1102c660dd35725a11c7ca9365c237f2f42f6b30;p=mirror_ubuntu-bionic-kernel.git diff --git a/kernel/sched.c b/kernel/sched.c index 2d12893b8b0f..3f2e502d609b 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -605,10 +605,10 @@ static inline int cpu_of(struct rq *rq) /* * Return the group to which this tasks belongs. * - * We use task_subsys_state_check() and extend the RCU verification - * with lockdep_is_held(&p->pi_lock) because cpu_cgroup_attach() - * holds that lock for each task it moves into the cgroup. Therefore - * by holding that lock, we pin the task to the current cgroup. + * We use task_subsys_state_check() and extend the RCU verification with + * pi->lock and rq->lock because cpu_cgroup_attach() holds those locks for each + * task it moves into the cgroup. Therefore by holding either of those locks, + * we pin the task to the current cgroup. */ static inline struct task_group *task_group(struct task_struct *p) { @@ -616,7 +616,8 @@ static inline struct task_group *task_group(struct task_struct *p) struct cgroup_subsys_state *css; css = task_subsys_state_check(p, cpu_cgroup_subsys_id, - lockdep_is_held(&p->pi_lock)); + lockdep_is_held(&p->pi_lock) || + lockdep_is_held(&task_rq(p)->lock)); tg = container_of(css, struct task_group, css); return autogroup_task_group(p, tg); @@ -2200,6 +2201,16 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu) !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE)); #ifdef CONFIG_LOCKDEP + /* + * The caller should hold either p->pi_lock or rq->lock, when changing + * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks. + * + * sched_move_task() holds both and thus holding either pins the cgroup, + * see set_task_rq(). + * + * Furthermore, all task_rq users should acquire both locks, see + * task_rq_lock(). + */ WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || lockdep_is_held(&task_rq(p)->lock))); #endif @@ -2447,6 +2458,10 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags) } rcu_read_unlock(); } + + if (wake_flags & WF_MIGRATED) + schedstat_inc(p, se.statistics.nr_wakeups_migrate); + #endif /* CONFIG_SMP */ schedstat_inc(rq, ttwu_count); @@ -2455,9 +2470,6 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags) if (wake_flags & WF_SYNC) schedstat_inc(p, se.statistics.nr_wakeups_sync); - if (cpu != task_cpu(p)) - schedstat_inc(p, se.statistics.nr_wakeups_migrate); - #endif /* CONFIG_SCHEDSTATS */ } @@ -2573,7 +2585,26 @@ static void ttwu_queue_remote(struct task_struct *p, int cpu) if (!next) smp_send_reschedule(cpu); } -#endif + +#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW +static int ttwu_activate_remote(struct task_struct *p, int wake_flags) +{ + struct rq *rq; + int ret = 0; + + rq = __task_rq_lock(p); + if (p->on_cpu) { + ttwu_activate(rq, p, ENQUEUE_WAKEUP); + ttwu_do_wakeup(rq, p, wake_flags); + ret = 1; + } + __task_rq_unlock(rq); + + return ret; + +} +#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */ +#endif /* CONFIG_SMP */ static void ttwu_queue(struct task_struct *p, int cpu) { @@ -2581,6 +2612,7 @@ static void ttwu_queue(struct task_struct *p, int cpu) #if defined(CONFIG_SMP) if (sched_feat(TTWU_QUEUE) && cpu != smp_processor_id()) { + sched_clock_cpu(cpu); /* sync clocks x-cpu */ ttwu_queue_remote(p, cpu); return; } @@ -2631,17 +2663,17 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) while (p->on_cpu) { #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW /* - * If called from interrupt context we could have landed in the - * middle of schedule(), in this case we should take care not - * to spin on ->on_cpu if p is current, since that would - * deadlock. + * In case the architecture enables interrupts in + * context_switch(), we cannot busy wait, since that + * would lead to deadlocks when an interrupt hits and + * tries to wake up @prev. So bail and do a complete + * remote wakeup. */ - if (p == current) { - ttwu_queue(p, cpu); + if (ttwu_activate_remote(p, wake_flags)) goto stat; - } -#endif +#else cpu_relax(); +#endif } /* * Pairs with the smp_wmb() in finish_lock_switch(). @@ -2655,8 +2687,10 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) p->sched_class->task_waking(p); cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags); - if (task_cpu(p) != cpu) + if (task_cpu(p) != cpu) { + wake_flags |= WF_MIGRATED; set_task_cpu(p, cpu); + } #endif /* CONFIG_SMP */ ttwu_queue(p, cpu); @@ -5841,7 +5875,7 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu) idle->state = TASK_RUNNING; idle->se.exec_start = sched_clock(); - cpumask_copy(&idle->cpus_allowed, cpumask_of(cpu)); + do_set_cpus_allowed(idle, cpumask_of(cpu)); /* * We're having a chicken and egg problem, even though we are * holding rq->lock, the cpu isn't yet set to this cpu so the @@ -5929,6 +5963,16 @@ static inline void sched_init_granularity(void) } #ifdef CONFIG_SMP +void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) +{ + if (p->sched_class && p->sched_class->set_cpus_allowed) + p->sched_class->set_cpus_allowed(p, new_mask); + else { + cpumask_copy(&p->cpus_allowed, new_mask); + p->rt.nr_cpus_allowed = cpumask_weight(new_mask); + } +} + /* * This is how migration works: * @@ -5974,12 +6018,7 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) goto out; } - if (p->sched_class->set_cpus_allowed) - p->sched_class->set_cpus_allowed(p, new_mask); - else { - cpumask_copy(&p->cpus_allowed, new_mask); - p->rt.nr_cpus_allowed = cpumask_weight(new_mask); - } + do_set_cpus_allowed(p, new_mask); /* Can the task run on the task's current CPU? If so, we're done */ if (cpumask_test_cpu(task_cpu(p), new_mask)) @@ -8764,42 +8803,10 @@ cpu_cgroup_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk) return 0; } -static int -cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, - struct task_struct *tsk, bool threadgroup) -{ - int retval = cpu_cgroup_can_attach_task(cgrp, tsk); - if (retval) - return retval; - if (threadgroup) { - struct task_struct *c; - rcu_read_lock(); - list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) { - retval = cpu_cgroup_can_attach_task(cgrp, c); - if (retval) { - rcu_read_unlock(); - return retval; - } - } - rcu_read_unlock(); - } - return 0; -} - static void -cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp, - struct cgroup *old_cont, struct task_struct *tsk, - bool threadgroup) +cpu_cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) { sched_move_task(tsk); - if (threadgroup) { - struct task_struct *c; - rcu_read_lock(); - list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) { - sched_move_task(c); - } - rcu_read_unlock(); - } } static void @@ -8887,8 +8894,8 @@ struct cgroup_subsys cpu_cgroup_subsys = { .name = "cpu", .create = cpu_cgroup_create, .destroy = cpu_cgroup_destroy, - .can_attach = cpu_cgroup_can_attach, - .attach = cpu_cgroup_attach, + .can_attach_task = cpu_cgroup_can_attach_task, + .attach_task = cpu_cgroup_attach_task, .exit = cpu_cgroup_exit, .populate = cpu_cgroup_populate, .subsys_id = cpu_cgroup_subsys_id,