diff options
author | Mark Brown <broonie@kernel.org> | 2016-11-04 12:16:38 -0600 |
---|---|---|
committer | Mark Brown <broonie@kernel.org> | 2016-11-04 12:16:38 -0600 |
commit | cc9b94029e9ef51787af908e9856b1eed314bc00 (patch) | |
tree | 9675310b89d0f6fb1f7bd9423f0638c4ee5226fd /kernel/sched/core.c | |
parent | 13bed58ce8748d430a26e353a09b89f9d613a71f (diff) | |
parent | 1b5b42216469b05ef4b5916cb40b127dfab1da88 (diff) |
Merge branch 'topic/error' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator into regulator-fixed
Diffstat (limited to 'kernel/sched/core.c')
-rw-r--r-- | kernel/sched/core.c | 543 |
1 files changed, 389 insertions, 154 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 7f2cae4620c7..94732d1ab00a 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -74,6 +74,7 @@ #include <linux/context_tracking.h> #include <linux/compiler.h> #include <linux/frame.h> +#include <linux/prefetch.h> #include <asm/switch_to.h> #include <asm/tlb.h> @@ -580,6 +581,8 @@ static bool wake_up_full_nohz_cpu(int cpu) * If needed we can still optimize that later with an * empty IRQ. */ + if (cpu_is_offline(cpu)) + return true; /* Don't try to wake offline CPUs. */ if (tick_nohz_full_cpu(cpu)) { if (cpu != smp_processor_id() || tick_nohz_tick_stopped()) @@ -590,6 +593,11 @@ static bool wake_up_full_nohz_cpu(int cpu) return false; } +/* + * Wake up the specified CPU. If the CPU is going offline, it is the + * caller's responsibility to deal with the lost wakeup, for example, + * by hooking into the CPU_DEAD notifier like timers and hrtimers do. + */ void wake_up_nohz_cpu(int cpu) { if (!wake_up_full_nohz_cpu(cpu)) @@ -1062,8 +1070,12 @@ static int migration_cpu_stop(void *data) * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because * we're holding p->pi_lock. */ - if (task_rq(p) == rq && task_on_rq_queued(p)) - rq = __migrate_task(rq, p, arg->dest_cpu); + if (task_rq(p) == rq) { + if (task_on_rq_queued(p)) + rq = __migrate_task(rq, p, arg->dest_cpu); + else + p->wake_cpu = arg->dest_cpu; + } raw_spin_unlock(&rq->lock); raw_spin_unlock(&p->pi_lock); @@ -1104,10 +1116,10 @@ void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask) p->sched_class->set_cpus_allowed(p, new_mask); - if (running) - p->sched_class->set_curr_task(rq); if (queued) enqueue_task(rq, p, ENQUEUE_RESTORE); + if (running) + set_curr_task(rq, p); } /* @@ -1264,7 +1276,7 @@ static void __migrate_swap_task(struct task_struct *p, int cpu) /* * Task isn't running anymore; make it appear like we migrated * it before it went to sleep. This means on wakeup we make the - * previous cpu our targer instead of where it really is. + * previous cpu our target instead of where it really is. */ p->wake_cpu = cpu; } @@ -1536,7 +1548,9 @@ static int select_fallback_rq(int cpu, struct task_struct *p) for (;;) { /* Any allowed, online CPU? */ for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) { - if (!cpu_active(dest_cpu)) + if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu)) + continue; + if (!cpu_online(dest_cpu)) continue; goto out; } @@ -1626,23 +1640,25 @@ static inline int __set_cpus_allowed_ptr(struct task_struct *p, static void ttwu_stat(struct task_struct *p, int cpu, int wake_flags) { -#ifdef CONFIG_SCHEDSTATS - struct rq *rq = this_rq(); + struct rq *rq; -#ifdef CONFIG_SMP - int this_cpu = smp_processor_id(); + if (!schedstat_enabled()) + return; - if (cpu == this_cpu) { - schedstat_inc(rq, ttwu_local); - schedstat_inc(p, se.statistics.nr_wakeups_local); + rq = this_rq(); + +#ifdef CONFIG_SMP + if (cpu == rq->cpu) { + schedstat_inc(rq->ttwu_local); + schedstat_inc(p->se.statistics.nr_wakeups_local); } else { struct sched_domain *sd; - schedstat_inc(p, se.statistics.nr_wakeups_remote); + schedstat_inc(p->se.statistics.nr_wakeups_remote); rcu_read_lock(); - for_each_domain(this_cpu, sd) { + for_each_domain(rq->cpu, sd) { if (cpumask_test_cpu(cpu, sched_domain_span(sd))) { - schedstat_inc(sd, ttwu_wake_remote); + schedstat_inc(sd->ttwu_wake_remote); break; } } @@ -1650,17 +1666,14 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags) } if (wake_flags & WF_MIGRATED) - schedstat_inc(p, se.statistics.nr_wakeups_migrate); - + schedstat_inc(p->se.statistics.nr_wakeups_migrate); #endif /* CONFIG_SMP */ - schedstat_inc(rq, ttwu_count); - schedstat_inc(p, se.statistics.nr_wakeups); + schedstat_inc(rq->ttwu_count); + schedstat_inc(p->se.statistics.nr_wakeups); if (wake_flags & WF_SYNC) - schedstat_inc(p, se.statistics.nr_wakeups_sync); - -#endif /* CONFIG_SCHEDSTATS */ + schedstat_inc(p->se.statistics.nr_wakeups_sync); } static inline void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags) @@ -1935,7 +1948,7 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) * chain to provide order. Instead we do: * * 1) smp_store_release(X->on_cpu, 0) - * 2) smp_cond_acquire(!X->on_cpu) + * 2) smp_cond_load_acquire(!X->on_cpu) * * Example: * @@ -1946,7 +1959,7 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) * sched-out X * smp_store_release(X->on_cpu, 0); * - * smp_cond_acquire(!X->on_cpu); + * smp_cond_load_acquire(&X->on_cpu, !VAL); * X->state = WAKING * set_task_cpu(X,2) * @@ -1972,7 +1985,7 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) * This means that any means of doing remote wakeups must order the CPU doing * the wakeup against the CPU the task is going to end up running on. This, * however, is already required for the regular Program-Order guarantee above, - * since the waking CPU is the one issueing the ACQUIRE (smp_cond_acquire). + * since the waking CPU is the one issueing the ACQUIRE (smp_cond_load_acquire). * */ @@ -2013,6 +2026,28 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) success = 1; /* we're going to change ->state */ cpu = task_cpu(p); + /* + * Ensure we load p->on_rq _after_ p->state, otherwise it would + * be possible to, falsely, observe p->on_rq == 0 and get stuck + * in smp_cond_load_acquire() below. + * + * sched_ttwu_pending() try_to_wake_up() + * [S] p->on_rq = 1; [L] P->state + * UNLOCK rq->lock -----. + * \ + * +--- RMB + * schedule() / + * LOCK rq->lock -----' + * UNLOCK rq->lock + * + * [task p] + * [S] p->state = UNINTERRUPTIBLE [L] p->on_rq + * + * Pairs with the UNLOCK+LOCK on rq->lock from the + * last wakeup of our task and the schedule that got our task + * current. + */ + smp_rmb(); if (p->on_rq && ttwu_remote(p, wake_flags)) goto stat; @@ -2045,7 +2080,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) * This ensures that tasks getting woken will be fully ordered against * their previous state and preserve Program Order. */ - smp_cond_acquire(!p->on_cpu); + smp_cond_load_acquire(&p->on_cpu, !VAL); p->sched_contributes_to_load = !!task_contributes_to_load(p); p->state = TASK_WAKING; @@ -2059,8 +2094,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) ttwu_queue(p, cpu, wake_flags); stat: - if (schedstat_enabled()) - ttwu_stat(p, cpu, wake_flags); + ttwu_stat(p, cpu, wake_flags); out: raw_spin_unlock_irqrestore(&p->pi_lock, flags); @@ -2070,6 +2104,7 @@ out: /** * try_to_wake_up_local - try to wake up a local task with rq lock held * @p: the thread to be awakened + * @cookie: context's cookie for pinning * * Put @p on the run-queue if it's not already there. The caller must * ensure that this_rq() is locked, @p is bound to this_rq() and not @@ -2108,8 +2143,7 @@ static void try_to_wake_up_local(struct task_struct *p, struct pin_cookie cookie ttwu_activate(rq, p, ENQUEUE_WAKEUP); ttwu_do_wakeup(rq, p, 0, cookie); - if (schedstat_enabled()) - ttwu_stat(p, smp_processor_id(), 0); + ttwu_stat(p, smp_processor_id(), 0); out: raw_spin_unlock(&p->pi_lock); } @@ -2253,9 +2287,11 @@ int sysctl_numa_balancing(struct ctl_table *table, int write, #endif #endif +#ifdef CONFIG_SCHEDSTATS + DEFINE_STATIC_KEY_FALSE(sched_schedstats); +static bool __initdata __sched_schedstats = false; -#ifdef CONFIG_SCHEDSTATS static void set_schedstats(bool enabled) { if (enabled) @@ -2278,11 +2314,16 @@ static int __init setup_schedstats(char *str) if (!str) goto out; + /* + * This code is called before jump labels have been set up, so we can't + * change the static branch directly just yet. Instead set a temporary + * variable so init_schedstats() can do it later. + */ if (!strcmp(str, "enable")) { - set_schedstats(true); + __sched_schedstats = true; ret = 1; } else if (!strcmp(str, "disable")) { - set_schedstats(false); + __sched_schedstats = false; ret = 1; } out: @@ -2293,6 +2334,11 @@ out: } __setup("schedstats=", setup_schedstats); +static void __init init_schedstats(void) +{ + set_schedstats(__sched_schedstats); +} + #ifdef CONFIG_PROC_SYSCTL int sysctl_schedstats(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) @@ -2313,8 +2359,10 @@ int sysctl_schedstats(struct ctl_table *table, int write, set_schedstats(state); return err; } -#endif -#endif +#endif /* CONFIG_PROC_SYSCTL */ +#else /* !CONFIG_SCHEDSTATS */ +static inline void init_schedstats(void) {} +#endif /* CONFIG_SCHEDSTATS */ /* * fork()/clone()-time setup: @@ -2326,11 +2374,11 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p) __sched_fork(clone_flags, p); /* - * We mark the process as running here. This guarantees that + * We mark the process as NEW here. This guarantees that * nobody will actually run it, and a signal or other external * event cannot wake it up and insert it on the runqueue either. */ - p->state = TASK_RUNNING; + p->state = TASK_NEW; /* * Make sure we do not leak PI boosting priority to the child. @@ -2367,8 +2415,7 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p) p->sched_class = &fair_sched_class; } - if (p->sched_class->task_fork) - p->sched_class->task_fork(p); + init_entity_runnable_average(&p->se); /* * The child is not yet in the pid-hash so no cgroup attach races, @@ -2378,7 +2425,13 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p) * Silence PROVE_RCU. */ raw_spin_lock_irqsave(&p->pi_lock, flags); - set_task_cpu(p, cpu); + /* + * We're setting the cpu for the first time, we don't migrate, + * so use __set_task_cpu(). + */ + __set_task_cpu(p, cpu); + if (p->sched_class->task_fork) + p->sched_class->task_fork(p); raw_spin_unlock_irqrestore(&p->pi_lock, flags); #ifdef CONFIG_SCHED_INFO @@ -2510,21 +2563,22 @@ void wake_up_new_task(struct task_struct *p) struct rq_flags rf; struct rq *rq; - /* Initialize new task's runnable average */ - init_entity_runnable_average(&p->se); raw_spin_lock_irqsave(&p->pi_lock, rf.flags); + p->state = TASK_RUNNING; #ifdef CONFIG_SMP /* * Fork balancing, do it here and not earlier because: * - cpus_allowed can change in the fork path * - any previously selected cpu might disappear through hotplug + * + * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq, + * as we're not fully set-up yet. */ - set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0)); + __set_task_cpu(p, select_task_rq(p, task_cpu(p), SD_BALANCE_FORK, 0)); #endif - /* Post initialize new task's util average when its cfs_rq is set */ + rq = __task_rq_lock(p, &rf); post_init_entity_util_avg(&p->se); - rq = __task_rq_lock(p, &rf); activate_task(rq, p, 0); p->on_rq = TASK_ON_RQ_QUEUED; trace_sched_wakeup_new(p); @@ -2727,6 +2781,10 @@ static struct rq *finish_task_switch(struct task_struct *prev) * task and put them back on the free list. */ kprobe_flush_task(prev); + + /* Task is done with its stack. */ + put_task_stack(prev); + put_task_struct(prev); } @@ -2950,6 +3008,23 @@ EXPORT_PER_CPU_SYMBOL(kstat); EXPORT_PER_CPU_SYMBOL(kernel_cpustat); /* + * The function fair_sched_class.update_curr accesses the struct curr + * and its field curr->exec_start; when called from task_sched_runtime(), + * we observe a high rate of cache misses in practice. + * Prefetching this data results in improved performance. + */ +static inline void prefetch_curr_exec_start(struct task_struct *p) +{ +#ifdef CONFIG_FAIR_GROUP_SCHED + struct sched_entity *curr = (&p->se)->cfs_rq->curr; +#else + struct sched_entity *curr = (&task_rq(p)->cfs)->curr; +#endif + prefetch(curr); + prefetch(&curr->exec_start); +} + +/* * Return accounted runtime for the task. * In case the task is currently running, return the runtime plus current's * pending runtime that have not been accounted yet. @@ -2983,6 +3058,7 @@ unsigned long long task_sched_runtime(struct task_struct *p) * thread, breaking clock_gettime(). */ if (task_current(rq, p) && task_on_rq_queued(p)) { + prefetch_curr_exec_start(p); update_rq_clock(rq); p->sched_class->update_curr(rq); } @@ -3129,6 +3205,9 @@ static inline void preempt_latency_stop(int val) { } */ static noinline void __schedule_bug(struct task_struct *prev) { + /* Save this before calling printk(), since that will clobber it */ + unsigned long preempt_disable_ip = get_preempt_disable_ip(current); + if (oops_in_progress) return; @@ -3139,13 +3218,15 @@ static noinline void __schedule_bug(struct task_struct *prev) print_modules(); if (irqs_disabled()) print_irqtrace_events(prev); -#ifdef CONFIG_DEBUG_PREEMPT - if (in_atomic_preempt_off()) { + if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) + && in_atomic_preempt_off()) { pr_err("Preemption disabled at:"); - print_ip_sym(current->preempt_disable_ip); + print_ip_sym(preempt_disable_ip); pr_cont("\n"); } -#endif + if (panic_on_warn) + panic("scheduling while atomic\n"); + dump_stack(); add_taint(TAINT_WARN, LOCKDEP_STILL_OK); } @@ -3156,7 +3237,8 @@ static noinline void __schedule_bug(struct task_struct *prev) static inline void schedule_debug(struct task_struct *prev) { #ifdef CONFIG_SCHED_STACK_END_CHECK - BUG_ON(task_stack_end_corrupted(prev)); + if (task_stack_end_corrupted(prev)) + panic("corrupted stack end detected inside scheduler\n"); #endif if (unlikely(in_atomic_preempt_off())) { @@ -3167,7 +3249,7 @@ static inline void schedule_debug(struct task_struct *prev) profile_hit(SCHED_PROFILING, __builtin_return_address(0)); - schedstat_inc(this_rq(), sched_count); + schedstat_inc(this_rq()->sched_count); } /* @@ -3260,17 +3342,6 @@ static void __sched notrace __schedule(bool preempt) rq = cpu_rq(cpu); prev = rq->curr; - /* - * do_exit() calls schedule() with preemption disabled as an exception; - * however we must fix that up, otherwise the next task will see an - * inconsistent (higher) preempt count. - * - * It also avoids the below schedule_debug() test from complaining - * about this. - */ - if (unlikely(prev->state == TASK_DEAD)) - preempt_enable_no_resched_notrace(); - schedule_debug(prev); if (sched_feat(HRTICK)) @@ -3336,7 +3407,33 @@ static void __sched notrace __schedule(bool preempt) balance_callback(rq); } -STACK_FRAME_NON_STANDARD(__schedule); /* switch_to() */ + +void __noreturn do_task_dead(void) +{ + /* + * The setting of TASK_RUNNING by try_to_wake_up() may be delayed + * when the following two conditions become true. + * - There is race condition of mmap_sem (It is acquired by + * exit_mm()), and + * - SMI occurs before setting TASK_RUNINNG. + * (or hypervisor of virtual machine switches to other guest) + * As a result, we may become TASK_RUNNING after becoming TASK_DEAD + * + * To avoid it, we have to wait for releasing tsk->pi_lock which + * is held by try_to_wake_up() + */ + smp_mb(); + raw_spin_unlock_wait(¤t->pi_lock); + + /* causes final put_task_struct in finish_task_switch(). */ + __set_current_state(TASK_DEAD); + current->flags |= PF_NOFREEZE; /* tell freezer to ignore us */ + __schedule(false); + BUG(); + /* Avoid "noreturn function does return". */ + for (;;) + cpu_relax(); /* For when BUG is null */ +} static inline void sched_submit_work(struct task_struct *tsk) { @@ -3620,10 +3717,10 @@ void rt_mutex_setprio(struct task_struct *p, int prio) p->prio = prio; - if (running) - p->sched_class->set_curr_task(rq); if (queued) enqueue_task(rq, p, queue_flag); + if (running) + set_curr_task(rq, p); check_class_changed(rq, p, prev_class, oldprio); out_unlock: @@ -3637,7 +3734,8 @@ out_unlock: void set_user_nice(struct task_struct *p, long nice) { - int old_prio, delta, queued; + bool queued, running; + int old_prio, delta; struct rq_flags rf; struct rq *rq; @@ -3659,8 +3757,11 @@ void set_user_nice(struct task_struct *p, long nice) goto out_unlock; } queued = task_on_rq_queued(p); + running = task_current(rq, p); if (queued) dequeue_task(rq, p, DEQUEUE_SAVE); + if (running) + put_prev_task(rq, p); p->static_prio = NICE_TO_PRIO(nice); set_load_weight(p); @@ -3677,6 +3778,8 @@ void set_user_nice(struct task_struct *p, long nice) if (delta < 0 || (delta > 0 && task_running(rq, p))) resched_curr(rq); } + if (running) + set_curr_task(rq, p); out_unlock: task_rq_unlock(rq, p, &rf); } @@ -4176,8 +4279,6 @@ change: prev_class = p->sched_class; __setscheduler(rq, p, attr, pi); - if (running) - p->sched_class->set_curr_task(rq); if (queued) { /* * We enqueue to tail when the priority of a task is @@ -4188,6 +4289,8 @@ change: enqueue_task(rq, p, queue_flags); } + if (running) + set_curr_task(rq, p); check_class_changed(rq, p, prev_class, oldprio); preempt_disable(); /* avoid rq from going away on us */ @@ -4736,7 +4839,8 @@ out_unlock: * @len: length in bytes of the bitmask pointed to by user_mask_ptr * @user_mask_ptr: user-space pointer to hold the current cpu mask * - * Return: 0 on success. An error code otherwise. + * Return: size of CPU mask copied to user_mask_ptr on success. An + * error code otherwise. */ SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len, unsigned long __user *, user_mask_ptr) @@ -4778,7 +4882,7 @@ SYSCALL_DEFINE0(sched_yield) { struct rq *rq = this_rq_lock(); - schedstat_inc(rq, yld_count); + schedstat_inc(rq->yld_count); current->sched_class->yield_task(rq); /* @@ -4795,6 +4899,7 @@ SYSCALL_DEFINE0(sched_yield) return 0; } +#ifndef CONFIG_PREEMPT int __sched _cond_resched(void) { if (should_resched(0)) { @@ -4804,6 +4909,7 @@ int __sched _cond_resched(void) return 0; } EXPORT_SYMBOL(_cond_resched); +#endif /* * __cond_resched_lock() - if a reschedule is pending, drop the given lock, @@ -4929,7 +5035,7 @@ again: yielded = curr->sched_class->yield_to_task(rq, p, preempt); if (yielded) { - schedstat_inc(rq, yld_count); + schedstat_inc(rq->yld_count); /* * Make p's CPU reschedule; pick_next_entity takes care of * fairness. @@ -5133,14 +5239,16 @@ void show_state_filter(unsigned long state_filter) /* * reset the NMI-timeout, listing all files on a slow * console might take a lot of time: + * Also, reset softlockup watchdogs on all CPUs, because + * another CPU might be blocked waiting for us to process + * an IPI. */ touch_nmi_watchdog(); + touch_all_softlockup_watchdogs(); if (!state_filter || (p->state & state_filter)) sched_show_task(p); } - touch_all_softlockup_watchdogs(); - #ifdef CONFIG_SCHED_DEBUG if (!state_filter) sysrq_sched_debug_show(); @@ -5347,10 +5455,10 @@ void sched_setnuma(struct task_struct *p, int nid) p->numa_preferred_nid = nid; - if (running) - p->sched_class->set_curr_task(rq); if (queued) enqueue_task(rq, p, ENQUEUE_RESTORE); + if (running) + set_curr_task(rq, p); task_rq_unlock(rq, p, &rf); } #endif /* CONFIG_NUMA_BALANCING */ @@ -5376,13 +5484,15 @@ void idle_task_exit(void) /* * Since this CPU is going 'away' for a while, fold any nr_active delta * we might have. Assumes we're called after migrate_tasks() so that the - * nr_active count is stable. + * nr_active count is stable. We need to take the teardown thread which + * is calling this into account, so we hand in adjust = 1 to the load + * calculation. * * Also see the comment "Global load-average calculations". */ static void calc_load_migrate(struct rq *rq) { - long delta = calc_load_fold_active(rq); + long delta = calc_load_fold_active(rq, 1); if (delta) atomic_long_add(delta, &calc_load_tasks); } @@ -5645,6 +5755,8 @@ static void sched_domain_debug(struct sched_domain *sd, int cpu) } } #else /* !CONFIG_SCHED_DEBUG */ + +# define sched_debug_enabled 0 # define sched_domain_debug(sd, cpu) do { } while (0) static inline bool sched_debug(void) { @@ -5663,6 +5775,7 @@ static int sd_degenerate(struct sched_domain *sd) SD_BALANCE_FORK | SD_BALANCE_EXEC | SD_SHARE_CPUCAPACITY | + SD_ASYM_CPUCAPACITY | SD_SHARE_PKG_RESOURCES | SD_SHARE_POWERDOMAIN)) { if (sd->groups != sd->groups->next) @@ -5693,6 +5806,7 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) SD_BALANCE_NEWIDLE | SD_BALANCE_FORK | SD_BALANCE_EXEC | + SD_ASYM_CPUCAPACITY | SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES | SD_PREFER_SIBLING | @@ -5837,10 +5951,8 @@ static void free_sched_groups(struct sched_group *sg, int free_sgc) } while (sg != first); } -static void free_sched_domain(struct rcu_head *rcu) +static void destroy_sched_domain(struct sched_domain *sd) { - struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu); - /* * If its an overlapping domain it has private groups, iterate and * nuke them all. @@ -5851,18 +5963,26 @@ static void free_sched_domain(struct rcu_head *rcu) kfree(sd->groups->sgc); kfree(sd->groups); } + if (sd->shared && atomic_dec_and_test(&sd->shared->ref)) + kfree(sd->shared); kfree(sd); } -static void destroy_sched_domain(struct sched_domain *sd, int cpu) +static void destroy_sched_domains_rcu(struct rcu_head *rcu) { - call_rcu(&sd->rcu, free_sched_domain); + struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu); + + while (sd) { + struct sched_domain *parent = sd->parent; + destroy_sched_domain(sd); + sd = parent; + } } -static void destroy_sched_domains(struct sched_domain *sd, int cpu) +static void destroy_sched_domains(struct sched_domain *sd) { - for (; sd; sd = sd->parent) - destroy_sched_domain(sd, cpu); + if (sd) + call_rcu(&sd->rcu, destroy_sched_domains_rcu); } /* @@ -5877,14 +5997,14 @@ static void destroy_sched_domains(struct sched_domain *sd, int cpu) DEFINE_PER_CPU(struct sched_domain *, sd_llc); DEFINE_PER_CPU(int, sd_llc_size); DEFINE_PER_CPU(int, sd_llc_id); +DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared); DEFINE_PER_CPU(struct sched_domain *, sd_numa); -DEFINE_PER_CPU(struct sched_domain *, sd_busy); DEFINE_PER_CPU(struct sched_domain *, sd_asym); static void update_top_cache_domain(int cpu) { + struct sched_domain_shared *sds = NULL; struct sched_domain *sd; - struct sched_domain *busy_sd = NULL; int id = cpu; int size = 1; @@ -5892,13 +6012,13 @@ static void update_top_cache_domain(int cpu) if (sd) { id = cpumask_first(sched_domain_span(sd)); size = cpumask_weight(sched_domain_span(sd)); - busy_sd = sd->parent; /* sd_busy */ + sds = sd->shared; } - rcu_assign_pointer(per_cpu(sd_busy, cpu), busy_sd); rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); per_cpu(sd_llc_size, cpu) = size; per_cpu(sd_llc_id, cpu) = id; + rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds); sd = lowest_flag_domain(cpu, SD_NUMA); rcu_assign_pointer(per_cpu(sd_numa, cpu), sd); @@ -5934,7 +6054,7 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) */ if (parent->flags & SD_PREFER_SIBLING) tmp->flags |= SD_PREFER_SIBLING; - destroy_sched_domain(parent, cpu); + destroy_sched_domain(parent); } else tmp = tmp->parent; } @@ -5942,7 +6062,7 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) if (sd && sd_degenerate(sd)) { tmp = sd; sd = sd->parent; - destroy_sched_domain(tmp, cpu); + destroy_sched_domain(tmp); if (sd) sd->child = NULL; } @@ -5952,7 +6072,7 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) rq_attach_root(rq, rd); tmp = rq->sd; rcu_assign_pointer(rq->sd, sd); - destroy_sched_domains(tmp, cpu); + destroy_sched_domains(tmp); update_top_cache_domain(cpu); } @@ -6195,7 +6315,6 @@ static void init_sched_groups_capacity(int cpu, struct sched_domain *sd) return; update_group_capacity(sd, cpu); - atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight); } /* @@ -6283,6 +6402,9 @@ static void claim_allocations(int cpu, struct sched_domain *sd) WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd); *per_cpu_ptr(sdd->sd, cpu) = NULL; + if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref)) + *per_cpu_ptr(sdd->sds, cpu) = NULL; + if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref)) *per_cpu_ptr(sdd->sg, cpu) = NULL; @@ -6302,26 +6424,37 @@ static int sched_domains_curr_level; /* * SD_flags allowed in topology descriptions. * - * SD_SHARE_CPUCAPACITY - describes SMT topologies - * SD_SHARE_PKG_RESOURCES - describes shared caches - * SD_NUMA - describes NUMA topologies - * SD_SHARE_POWERDOMAIN - describes shared power domain + * These flags are purely descriptive of the topology and do not prescribe + * behaviour. Behaviour is artificial and mapped in the below sd_init() + * function: + * + * SD_SHARE_CPUCAPACITY - describes SMT topologies + * SD_SHARE_PKG_RESOURCES - describes shared caches + * SD_NUMA - describes NUMA topologies + * SD_SHARE_POWERDOMAIN - describes shared power domain + * SD_ASYM_CPUCAPACITY - describes mixed capacity topologies + * + * Odd one out, which beside describing the topology has a quirk also + * prescribes the desired behaviour that goes along with it: * - * Odd one out: - * SD_ASYM_PACKING - describes SMT quirks + * SD_ASYM_PACKING - describes SMT quirks */ #define TOPOLOGY_SD_FLAGS \ (SD_SHARE_CPUCAPACITY | \ SD_SHARE_PKG_RESOURCES | \ SD_NUMA | \ SD_ASYM_PACKING | \ + SD_ASYM_CPUCAPACITY | \ SD_SHARE_POWERDOMAIN) static struct sched_domain * -sd_init(struct sched_domain_topology_level *tl, int cpu) +sd_init(struct sched_domain_topology_level *tl, + const struct cpumask *cpu_map, + struct sched_domain *child, int cpu) { - struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu); - int sd_weight, sd_flags = 0; + struct sd_data *sdd = &tl->data; + struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu); + int sd_id, sd_weight, sd_flags = 0; #ifdef CONFIG_NUMA /* @@ -6370,15 +6503,26 @@ sd_init(struct sched_domain_topology_level *tl, int cpu) .smt_gain = 0, .max_newidle_lb_cost = 0, .next_decay_max_lb_cost = jiffies, + .child = child, #ifdef CONFIG_SCHED_DEBUG .name = tl->name, #endif }; + cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); + sd_id = cpumask_first(sched_domain_span(sd)); + /* * Convert topological properties into behaviour. */ + if (sd->flags & SD_ASYM_CPUCAPACITY) { + struct sched_domain *t = sd; + + for_each_lower_domain(t) + t->flags |= SD_BALANCE_WAKE; + } + if (sd->flags & SD_SHARE_CPUCAPACITY) { sd->flags |= SD_PREFER_SIBLING; sd->imbalance_pct = 110; @@ -6410,7 +6554,17 @@ sd_init(struct sched_domain_topology_level *tl, int cpu) sd->idle_idx = 1; } - sd->private = &tl->data; + /* + * For all levels sharing cache; connect a sched_domain_shared + * instance. + */ + if (sd->flags & SD_SHARE_PKG_RESOURCES) { + sd->shared = *per_cpu_ptr(sdd->sds, sd_id); + atomic_inc(&sd->shared->ref); + atomic_set(&sd->shared->nr_busy_cpus, sd_weight); + } + + sd->private = sdd; return sd; } @@ -6437,6 +6591,9 @@ static struct sched_domain_topology_level *sched_domain_topology = void set_sched_topology(struct sched_domain_topology_level *tl) { + if (WARN_ON_ONCE(sched_smp_initialized)) + return; + sched_domain_topology = tl; } @@ -6717,6 +6874,10 @@ static int __sdt_alloc(const struct cpumask *cpu_map) if (!sdd->sd) return -ENOMEM; + sdd->sds = alloc_percpu(struct sched_domain_shared *); + if (!sdd->sds) + return -ENOMEM; + sdd->sg = alloc_percpu(struct sched_group *); if (!sdd->sg) return -ENOMEM; @@ -6727,6 +6888,7 @@ static int __sdt_alloc(const struct cpumask *cpu_map) for_each_cpu(j, cpu_map) { struct sched_domain *sd; + struct sched_domain_shared *sds; struct sched_group *sg; struct sched_group_capacity *sgc; @@ -6737,6 +6899,13 @@ static int __sdt_alloc(const struct cpumask *cpu_map) *per_cpu_ptr(sdd->sd, j) = sd; + sds = kzalloc_node(sizeof(struct sched_domain_shared), + GFP_KERNEL, cpu_to_node(j)); + if (!sds) + return -ENOMEM; + + *per_cpu_ptr(sdd->sds, j) = sds; + sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(), GFP_KERNEL, cpu_to_node(j)); if (!sg) @@ -6776,6 +6945,8 @@ static void __sdt_free(const struct cpumask *cpu_map) kfree(*per_cpu_ptr(sdd->sd, j)); } + if (sdd->sds) + kfree(*per_cpu_ptr(sdd->sds, j)); if (sdd->sg) kfree(*per_cpu_ptr(sdd->sg, j)); if (sdd->sgc) @@ -6783,6 +6954,8 @@ static void __sdt_free(const struct cpumask *cpu_map) } free_percpu(sdd->sd); sdd->sd = NULL; + free_percpu(sdd->sds); + sdd->sds = NULL; free_percpu(sdd->sg); sdd->sg = NULL; free_percpu(sdd->sgc); @@ -6794,16 +6967,12 @@ struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, const struct cpumask *cpu_map, struct sched_domain_attr *attr, struct sched_domain *child, int cpu) { - struct sched_domain *sd = sd_init(tl, cpu); - if (!sd) - return child; + struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu); - cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); if (child) { sd->level = child->level + 1; sched_domain_level_max = max(sched_domain_level_max, sd->level); child->parent = sd; - sd->child = child; if (!cpumask_subset(sched_domain_span(child), sched_domain_span(sd))) { @@ -6834,6 +7003,7 @@ static int build_sched_domains(const struct cpumask *cpu_map, enum s_alloc alloc_state; struct sched_domain *sd; struct s_data d; + struct rq *rq = NULL; int i, ret = -ENOMEM; alloc_state = __visit_domain_allocation_hell(&d, cpu_map); @@ -6884,11 +7054,22 @@ static int build_sched_domains(const struct cpumask *cpu_map, /* Attach the domains */ rcu_read_lock(); for_each_cpu(i, cpu_map) { + rq = cpu_rq(i); sd = *per_cpu_ptr(d.sd, i); + + /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */ + if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity)) + WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig); + cpu_attach_domain(sd, d.rd, i); } rcu_read_unlock(); + if (rq && sched_debug_enabled) { + pr_info("span: %*pbl (max cpu_capacity = %lu)\n", + cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity); + } + ret = 0; error: __free_domain_allocs(&d, alloc_state, cpu_map); @@ -7213,7 +7394,6 @@ static void sched_rq_cpu_starting(unsigned int cpu) struct rq *rq = cpu_rq(cpu); rq->calc_load_update = calc_load_update; - account_reset_rq(rq); update_max_interval(); } @@ -7248,6 +7428,22 @@ int sched_cpu_dying(unsigned int cpu) } #endif +#ifdef CONFIG_SCHED_SMT +DEFINE_STATIC_KEY_FALSE(sched_smt_present); + +static void sched_init_smt(void) +{ + /* + * We've enumerated all CPUs and will assume that if any CPU + * has SMT siblings, CPU0 will too. + */ + if (cpumask_weight(cpu_smt_mask(0)) > 1) + static_branch_enable(&sched_smt_present); +} +#else +static inline void sched_init_smt(void) { } +#endif + void __init sched_init_smp(void) { cpumask_var_t non_isolated_cpus; @@ -7277,6 +7473,9 @@ void __init sched_init_smp(void) init_sched_rt_class(); init_sched_dl_class(); + + sched_init_smt(); + sched_smp_initialized = true; } @@ -7314,6 +7513,7 @@ static struct kmem_cache *task_group_cache __read_mostly; #endif DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); +DECLARE_PER_CPU(cpumask_var_t, select_idle_mask); void __init sched_init(void) { @@ -7350,6 +7550,8 @@ void __init sched_init(void) for_each_possible_cpu(i) { per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node( cpumask_size(), GFP_KERNEL, cpu_to_node(i)); + per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node( + cpumask_size(), GFP_KERNEL, cpu_to_node(i)); } #endif /* CONFIG_CPUMASK_OFFSTACK */ @@ -7452,10 +7654,6 @@ void __init sched_init(void) set_load_weight(&init_task); -#ifdef CONFIG_PREEMPT_NOTIFIERS - INIT_HLIST_HEAD(&init_task.preempt_notifiers); -#endif - /* * The boot idle thread does lazy MMU switching as well: */ @@ -7463,11 +7661,6 @@ void __init sched_init(void) enter_lazy_tlb(&init_mm, current); /* - * During early bootup we pretend to be a normal task: - */ - current->sched_class = &fair_sched_class; - - /* * Make us the idle thread. Technically, schedule() should not be * called from this thread, however somewhere below it might be, * but because we are the idle thread, we just pick up running again @@ -7487,6 +7680,8 @@ void __init sched_init(void) #endif init_sched_fair_class(); + init_schedstats(); + scheduler_running = 1; } @@ -7519,6 +7714,7 @@ EXPORT_SYMBOL(__might_sleep); void ___might_sleep(const char *file, int line, int preempt_offset) { static unsigned long prev_jiffy; /* ratelimiting */ + unsigned long preempt_disable_ip; rcu_sleep_check(); /* WARN_ON_ONCE() by default, no rate limit reqd. */ if ((preempt_count_equals(preempt_offset) && !irqs_disabled() && @@ -7529,6 +7725,9 @@ void ___might_sleep(const char *file, int line, int preempt_offset) return; prev_jiffy = jiffies; + /* Save this before calling printk(), since that will clobber it */ + preempt_disable_ip = get_preempt_disable_ip(current); + printk(KERN_ERR "BUG: sleeping function called from invalid context at %s:%d\n", file, line); @@ -7543,14 +7742,14 @@ void ___might_sleep(const char *file, int line, int preempt_offset) debug_show_held_locks(current); if (irqs_disabled()) print_irqtrace_events(current); -#ifdef CONFIG_DEBUG_PREEMPT - if (!preempt_count_equals(preempt_offset)) { + if (IS_ENABLED(CONFIG_DEBUG_PREEMPT) + && !preempt_count_equals(preempt_offset)) { pr_err("Preemption disabled at:"); - print_ip_sym(current->preempt_disable_ip); + print_ip_sym(preempt_disable_ip); pr_cont("\n"); } -#endif dump_stack(); + add_taint(TAINT_WARN, LOCKDEP_STILL_OK); } EXPORT_SYMBOL(___might_sleep); #endif @@ -7571,12 +7770,10 @@ void normalize_rt_tasks(void) if (p->flags & PF_KTHREAD) continue; - p->se.exec_start = 0; -#ifdef CONFIG_SCHEDSTATS - p->se.statistics.wait_start = 0; - p->se.statistics.sleep_start = 0; - p->se.statistics.block_start = 0; -#endif + p->se.exec_start = 0; + schedstat_set(p->se.statistics.wait_start, 0); + schedstat_set(p->se.statistics.sleep_start, 0); + schedstat_set(p->se.statistics.block_start, 0); if (!dl_task(p) && !rt_task(p)) { /* @@ -7637,7 +7834,7 @@ struct task_struct *curr_task(int cpu) * * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED! */ -void set_curr_task(int cpu, struct task_struct *p) +void ia64_set_curr_task(int cpu, struct task_struct *p) { cpu_curr(cpu) = p; } @@ -7691,6 +7888,8 @@ void sched_online_group(struct task_group *tg, struct task_group *parent) INIT_LIST_HEAD(&tg->children); list_add_rcu(&tg->siblings, &parent->children); spin_unlock_irqrestore(&task_group_lock, flags); + + online_fair_sched_group(tg); } /* rcu callback to free various structures associated with a task group */ @@ -7719,27 +7918,9 @@ void sched_offline_group(struct task_group *tg) spin_unlock_irqrestore(&task_group_lock, flags); } -/* change task's runqueue when it moves between groups. - * The caller of this function should have put the task in its new group - * by now. This function just updates tsk->se.cfs_rq and tsk->se.parent to - * reflect its new group. - */ -void sched_move_task(struct task_struct *tsk) +static void sched_change_group(struct task_struct *tsk, int type) { struct task_group *tg; - int queued, running; - struct rq_flags rf; - struct rq *rq; - - rq = task_rq_lock(tsk, &rf); - - running = task_current(rq, tsk); - queued = task_on_rq_queued(tsk); - - if (queued) - dequeue_task(rq, tsk, DEQUEUE_SAVE | DEQUEUE_MOVE); - if (unlikely(running)) - put_prev_task(rq, tsk); /* * All callers are synchronized by task_rq_lock(); we do not use RCU @@ -7752,16 +7933,42 @@ void sched_move_task(struct task_struct *tsk) tsk->sched_task_group = tg; #ifdef CONFIG_FAIR_GROUP_SCHED - if (tsk->sched_class->task_move_group) - tsk->sched_class->task_move_group(tsk); + if (tsk->sched_class->task_change_group) + tsk->sched_class->task_change_group(tsk, type); else #endif set_task_rq(tsk, task_cpu(tsk)); +} + +/* + * Change task's runqueue when it moves between groups. + * + * The caller of this function should have put the task in its new group by + * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect + * its new group. + */ +void sched_move_task(struct task_struct *tsk) +{ + int queued, running; + struct rq_flags rf; + struct rq *rq; + + rq = task_rq_lock(tsk, &rf); + + running = task_current(rq, tsk); + queued = task_on_rq_queued(tsk); + if (queued) + dequeue_task(rq, tsk, DEQUEUE_SAVE | DEQUEUE_MOVE); if (unlikely(running)) - tsk->sched_class->set_curr_task(rq); + put_prev_task(rq, tsk); + + sched_change_group(tsk, TASK_MOVE_GROUP); + if (queued) enqueue_task(rq, tsk, ENQUEUE_RESTORE | ENQUEUE_MOVE); + if (unlikely(running)) + set_curr_task(rq, tsk); task_rq_unlock(rq, tsk, &rf); } @@ -8184,15 +8391,27 @@ static void cpu_cgroup_css_free(struct cgroup_subsys_state *css) sched_free_group(tg); } +/* + * This is called before wake_up_new_task(), therefore we really only + * have to set its group bits, all the other stuff does not apply. + */ static void cpu_cgroup_fork(struct task_struct *task) { - sched_move_task(task); + struct rq_flags rf; + struct rq *rq; + + rq = task_rq_lock(task, &rf); + + sched_change_group(task, TASK_SET_GROUP); + + task_rq_unlock(rq, task, &rf); } static int cpu_cgroup_can_attach(struct cgroup_taskset *tset) { struct task_struct *task; struct cgroup_subsys_state *css; + int ret = 0; cgroup_taskset_for_each(task, css, tset) { #ifdef CONFIG_RT_GROUP_SCHED @@ -8203,8 +8422,24 @@ static int cpu_cgroup_can_attach(struct cgroup_taskset *tset) if (task->sched_class != &fair_sched_class) return -EINVAL; #endif + /* + * Serialize against wake_up_new_task() such that if its + * running, we're sure to observe its full state. + */ + raw_spin_lock_irq(&task->pi_lock); + /* + * Avoid calling sched_move_task() before wake_up_new_task() + * has happened. This would lead to problems with PELT, due to + * move wanting to detach+attach while we're not attached yet. + */ + if (task->state == TASK_NEW) + ret = -EINVAL; + raw_spin_unlock_irq(&task->pi_lock); + + if (ret) + break; } - return 0; + return ret; } static void cpu_cgroup_attach(struct cgroup_taskset *tset) |