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authorMark Brown <broonie@kernel.org>2016-11-04 12:16:38 -0600
committerMark Brown <broonie@kernel.org>2016-11-04 12:16:38 -0600
commitcc9b94029e9ef51787af908e9856b1eed314bc00 (patch)
tree9675310b89d0f6fb1f7bd9423f0638c4ee5226fd /kernel/sched/core.c
parent13bed58ce8748d430a26e353a09b89f9d613a71f (diff)
parent1b5b42216469b05ef4b5916cb40b127dfab1da88 (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.c543
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(&current->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)