Merge branch 'perf/urgent' into perf/core

Merge reason: queue up dependent patch, update to -rc4

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 164 insertions, 143 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index d6527ac0f6e..e507af086b4 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2002,39 +2002,6 @@ static inline void check_class_changed(struct rq *rq, struct task_struct *p,
 		p->sched_class->prio_changed(rq, p, oldprio, running);
 }
 
-/**
- * kthread_bind - bind a just-created kthread to a cpu.
- * @p: thread created by kthread_create().
- * @cpu: cpu (might not be online, must be possible) for @k to run on.
- *
- * Description: This function is equivalent to set_cpus_allowed(),
- * except that @cpu doesn't need to be online, and the thread must be
- * stopped (i.e., just returned from kthread_create()).
- *
- * Function lives here instead of kthread.c because it messes with
- * scheduler internals which require locking.
- */
-void kthread_bind(struct task_struct *p, unsigned int cpu)
-{
-	struct rq *rq = cpu_rq(cpu);
-	unsigned long flags;
-
-	/* Must have done schedule() in kthread() before we set_task_cpu */
-	if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
-		WARN_ON(1);
-		return;
-	}
-
-	raw_spin_lock_irqsave(&rq->lock, flags);
-	update_rq_clock(rq);
-	set_task_cpu(p, cpu);
-	p->cpus_allowed = cpumask_of_cpu(cpu);
-	p->rt.nr_cpus_allowed = 1;
-	p->flags |= PF_THREAD_BOUND;
-	raw_spin_unlock_irqrestore(&rq->lock, flags);
-}
-EXPORT_SYMBOL(kthread_bind);
-
 #ifdef CONFIG_SMP
 /*
  * Is this task likely cache-hot:
@@ -2044,6 +2011,9 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
 {
 	s64 delta;
 
+	if (p->sched_class != &fair_sched_class)
+		return 0;
+
 	/*
 	 * Buddy candidates are cache hot:
 	 */
@@ -2052,9 +2022,6 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
 			 &p->se == cfs_rq_of(&p->se)->last))
 		return 1;
 
-	if (p->sched_class != &fair_sched_class)
-		return 0;
-
 	if (sysctl_sched_migration_cost == -1)
 		return 1;
 	if (sysctl_sched_migration_cost == 0)
@@ -2065,22 +2032,23 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
 	return delta < (s64)sysctl_sched_migration_cost;
 }
 
-
 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 {
-	int old_cpu = task_cpu(p);
-	struct cfs_rq *old_cfsrq = task_cfs_rq(p),
-		      *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu);
+#ifdef CONFIG_SCHED_DEBUG
+	/*
+	 * We should never call set_task_cpu() on a blocked task,
+	 * ttwu() will sort out the placement.
+	 */
+	WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
+			!(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
+#endif
 
 	trace_sched_migrate_task(p, new_cpu);
 
-	if (old_cpu != new_cpu) {
+	if (task_cpu(p) != new_cpu) {
 		p->se.nr_migrations++;
-		perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS,
-				     1, 1, NULL, 0);
+		perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 1, NULL, 0);
 	}
-	p->se.vruntime -= old_cfsrq->min_vruntime -
-					 new_cfsrq->min_vruntime;
 
 	__set_task_cpu(p, new_cpu);
 }
@@ -2105,13 +2073,10 @@ migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)
 
 	/*
 	 * If the task is not on a runqueue (and not running), then
-	 * it is sufficient to simply update the task's cpu field.
+	 * the next wake-up will properly place the task.
 	 */
-	if (!p->se.on_rq && !task_running(rq, p)) {
-		update_rq_clock(rq);
-		set_task_cpu(p, dest_cpu);
+	if (!p->se.on_rq && !task_running(rq, p))
 		return 0;
-	}
 
 	init_completion(&req->done);
 	req->task = p;
@@ -2317,10 +2282,73 @@ void task_oncpu_function_call(struct task_struct *p,
 }
 
 #ifdef CONFIG_SMP
+static int select_fallback_rq(int cpu, struct task_struct *p)
+{
+	int dest_cpu;
+	const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu));
+
+	/* Look for allowed, online CPU in same node. */
+	for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
+		if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
+			return dest_cpu;
+
+	/* Any allowed, online CPU? */
+	dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
+	if (dest_cpu < nr_cpu_ids)
+		return dest_cpu;
+
+	/* No more Mr. Nice Guy. */
+	if (dest_cpu >= nr_cpu_ids) {
+		rcu_read_lock();
+		cpuset_cpus_allowed_locked(p, &p->cpus_allowed);
+		rcu_read_unlock();
+		dest_cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed);
+
+		/*
+		 * Don't tell them about moving exiting tasks or
+		 * kernel threads (both mm NULL), since they never
+		 * leave kernel.
+		 */
+		if (p->mm && printk_ratelimit()) {
+			printk(KERN_INFO "process %d (%s) no "
+			       "longer affine to cpu%d\n",
+			       task_pid_nr(p), p->comm, cpu);
+		}
+	}
+
+	return dest_cpu;
+}
+
+/*
+ * Called from:
+ *
+ *  - fork, @p is stable because it isn't on the tasklist yet
+ *
+ *  - exec, @p is unstable, retry loop
+ *
+ *  - wake-up, we serialize ->cpus_allowed against TASK_WAKING so
+ *             we should be good.
+ */
 static inline
 int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
 {
-	return p->sched_class->select_task_rq(p, sd_flags, wake_flags);
+	int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags);
+
+	/*
+	 * In order not to call set_task_cpu() on a blocking task we need
+	 * to rely on ttwu() to place the task on a valid ->cpus_allowed
+	 * cpu.
+	 *
+	 * Since this is common to all placement strategies, this lives here.
+	 *
+	 * [ this allows ->select_task() to simply return task_cpu(p) and
+	 *   not worry about this generic constraint ]
+	 */
+	if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) ||
+		     !cpu_online(cpu)))
+		cpu = select_fallback_rq(task_cpu(p), p);
+
+	return cpu;
 }
 #endif
 
@@ -2375,6 +2403,10 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
 	if (task_contributes_to_load(p))
 		rq->nr_uninterruptible--;
 	p->state = TASK_WAKING;
+
+	if (p->sched_class->task_waking)
+		p->sched_class->task_waking(rq, p);
+
 	__task_rq_unlock(rq);
 
 	cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
@@ -2438,8 +2470,8 @@ out_running:
 
 	p->state = TASK_RUNNING;
 #ifdef CONFIG_SMP
-	if (p->sched_class->task_wake_up)
-		p->sched_class->task_wake_up(rq, p);
+	if (p->sched_class->task_woken)
+		p->sched_class->task_woken(rq, p);
 
 	if (unlikely(rq->idle_stamp)) {
 		u64 delta = rq->clock - rq->idle_stamp;
@@ -2538,14 +2570,6 @@ static void __sched_fork(struct task_struct *p)
 #ifdef CONFIG_PREEMPT_NOTIFIERS
 	INIT_HLIST_HEAD(&p->preempt_notifiers);
 #endif
-
-	/*
-	 * We mark the process as running here, but have not actually
-	 * inserted it onto the runqueue yet. 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;
 }
 
 /*
@@ -2556,6 +2580,12 @@ void sched_fork(struct task_struct *p, int clone_flags)
 	int cpu = get_cpu();
 
 	__sched_fork(p);
+	/*
+	 * We mark the process as waking 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_WAKING;
 
 	/*
 	 * Revert to default priority/policy on fork if requested.
@@ -2624,14 +2654,15 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
 	struct rq *rq;
 
 	rq = task_rq_lock(p, &flags);
-	BUG_ON(p->state != TASK_RUNNING);
+	BUG_ON(p->state != TASK_WAKING);
+	p->state = TASK_RUNNING;
 	update_rq_clock(rq);
 	activate_task(rq, p, 0);
 	trace_sched_wakeup_new(rq, p, 1);
 	check_preempt_curr(rq, p, WF_FORK);
 #ifdef CONFIG_SMP
-	if (p->sched_class->task_wake_up)
-		p->sched_class->task_wake_up(rq, p);
+	if (p->sched_class->task_woken)
+		p->sched_class->task_woken(rq, p);
 #endif
 	task_rq_unlock(rq, &flags);
 }
@@ -3101,21 +3132,36 @@ static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
 }
 
 /*
- * If dest_cpu is allowed for this process, migrate the task to it.
- * This is accomplished by forcing the cpu_allowed mask to only
- * allow dest_cpu, which will force the cpu onto dest_cpu. Then
- * the cpu_allowed mask is restored.
+ * sched_exec - execve() is a valuable balancing opportunity, because at
+ * this point the task has the smallest effective memory and cache footprint.
  */
-static void sched_migrate_task(struct task_struct *p, int dest_cpu)
+void sched_exec(void)
 {
+	struct task_struct *p = current;
 	struct migration_req req;
+	int dest_cpu, this_cpu;
 	unsigned long flags;
 	struct rq *rq;
 
+again:
+	this_cpu = get_cpu();
+	dest_cpu = select_task_rq(p, SD_BALANCE_EXEC, 0);
+	if (dest_cpu == this_cpu) {
+		put_cpu();
+		return;
+	}
+
 	rq = task_rq_lock(p, &flags);
+	put_cpu();
+
+	/*
+	 * select_task_rq() can race against ->cpus_allowed
+	 */
 	if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed)
-	    || unlikely(!cpu_active(dest_cpu)))
-		goto out;
+	    || unlikely(!cpu_active(dest_cpu))) {
+		task_rq_unlock(rq, &flags);
+		goto again;
+	}
 
 	/* force the process onto the specified CPU */
 	if (migrate_task(p, dest_cpu, &req)) {
@@ -3130,24 +3176,10 @@ static void sched_migrate_task(struct task_struct *p, int dest_cpu)
 
 		return;
 	}
-out:
 	task_rq_unlock(rq, &flags);
 }
 
 /*
- * sched_exec - execve() is a valuable balancing opportunity, because at
- * this point the task has the smallest effective memory and cache footprint.
- */
-void sched_exec(void)
-{
-	int new_cpu, this_cpu = get_cpu();
-	new_cpu = select_task_rq(current, SD_BALANCE_EXEC, 0);
-	put_cpu();
-	if (new_cpu != this_cpu)
-		sched_migrate_task(current, new_cpu);
-}
-
-/*
  * pull_task - move a task from a remote runqueue to the local runqueue.
  * Both runqueues must be locked.
  */
@@ -5911,14 +5943,15 @@ EXPORT_SYMBOL(wait_for_completion_killable);
  */
 bool try_wait_for_completion(struct completion *x)
 {
+	unsigned long flags;
 	int ret = 1;
 
-	spin_lock_irq(&x->wait.lock);
+	spin_lock_irqsave(&x->wait.lock, flags);
 	if (!x->done)
 		ret = 0;
 	else
 		x->done--;
-	spin_unlock_irq(&x->wait.lock);
+	spin_unlock_irqrestore(&x->wait.lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL(try_wait_for_completion);
@@ -5933,12 +5966,13 @@ EXPORT_SYMBOL(try_wait_for_completion);
  */
 bool completion_done(struct completion *x)
 {
+	unsigned long flags;
 	int ret = 1;
 
-	spin_lock_irq(&x->wait.lock);
+	spin_lock_irqsave(&x->wait.lock, flags);
 	if (!x->done)
 		ret = 0;
-	spin_unlock_irq(&x->wait.lock);
+	spin_unlock_irqrestore(&x->wait.lock, flags);
 	return ret;
 }
 EXPORT_SYMBOL(completion_done);
@@ -6457,7 +6491,7 @@ SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
 		return -EINVAL;
 
 	retval = -ESRCH;
-	read_lock(&tasklist_lock);
+	rcu_read_lock();
 	p = find_process_by_pid(pid);
 	if (p) {
 		retval = security_task_getscheduler(p);
@@ -6465,7 +6499,7 @@ SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
 			retval = p->policy
 				| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
 	}
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 	return retval;
 }
 
@@ -6483,7 +6517,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
 	if (!param || pid < 0)
 		return -EINVAL;
 
-	read_lock(&tasklist_lock);
+	rcu_read_lock();
 	p = find_process_by_pid(pid);
 	retval = -ESRCH;
 	if (!p)
@@ -6494,7 +6528,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
 		goto out_unlock;
 
 	lp.sched_priority = p->rt_priority;
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 
 	/*
 	 * This one might sleep, we cannot do it with a spinlock held ...
@@ -6504,7 +6538,7 @@ SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
 	return retval;
 
 out_unlock:
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 	return retval;
 }
 
@@ -6515,22 +6549,18 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
 	int retval;
 
 	get_online_cpus();
-	read_lock(&tasklist_lock);
+	rcu_read_lock();
 
 	p = find_process_by_pid(pid);
 	if (!p) {
-		read_unlock(&tasklist_lock);
+		rcu_read_unlock();
 		put_online_cpus();
 		return -ESRCH;
 	}
 
-	/*
-	 * It is not safe to call set_cpus_allowed with the
-	 * tasklist_lock held. We will bump the task_struct's
-	 * usage count and then drop tasklist_lock.
-	 */
+	/* Prevent p going away */
 	get_task_struct(p);
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 
 	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
 		retval = -ENOMEM;
@@ -6616,7 +6646,7 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask)
 	int retval;
 
 	get_online_cpus();
-	read_lock(&tasklist_lock);
+	rcu_read_lock();
 
 	retval = -ESRCH;
 	p = find_process_by_pid(pid);
@@ -6632,7 +6662,7 @@ long sched_getaffinity(pid_t pid, struct cpumask *mask)
 	task_rq_unlock(rq, &flags);
 
 out_unlock:
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 	put_online_cpus();
 
 	return retval;
@@ -6876,7 +6906,7 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
 		return -EINVAL;
 
 	retval = -ESRCH;
-	read_lock(&tasklist_lock);
+	rcu_read_lock();
 	p = find_process_by_pid(pid);
 	if (!p)
 		goto out_unlock;
@@ -6889,13 +6919,13 @@ SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
 	time_slice = p->sched_class->get_rr_interval(rq, p);
 	task_rq_unlock(rq, &flags);
 
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 	jiffies_to_timespec(time_slice, &t);
 	retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
 	return retval;
 
 out_unlock:
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 	return retval;
 }
 
@@ -6986,6 +7016,7 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
 	raw_spin_lock_irqsave(&rq->lock, flags);
 
 	__sched_fork(idle);
+	idle->state = TASK_RUNNING;
 	idle->se.exec_start = sched_clock();
 
 	cpumask_copy(&idle->cpus_allowed, cpumask_of(cpu));
@@ -7100,7 +7131,23 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
 	struct rq *rq;
 	int ret = 0;
 
+	/*
+	 * Since we rely on wake-ups to migrate sleeping tasks, don't change
+	 * the ->cpus_allowed mask from under waking tasks, which would be
+	 * possible when we change rq->lock in ttwu(), so synchronize against
+	 * TASK_WAKING to avoid that.
+	 */
+again:
+	while (p->state == TASK_WAKING)
+		cpu_relax();
+
 	rq = task_rq_lock(p, &flags);
+
+	if (p->state == TASK_WAKING) {
+		task_rq_unlock(rq, &flags);
+		goto again;
+	}
+
 	if (!cpumask_intersects(new_mask, cpu_active_mask)) {
 		ret = -EINVAL;
 		goto out;
@@ -7156,7 +7203,7 @@ EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
 static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
 {
 	struct rq *rq_dest, *rq_src;
-	int ret = 0, on_rq;
+	int ret = 0;
 
 	if (unlikely(!cpu_active(dest_cpu)))
 		return ret;
@@ -7172,12 +7219,13 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
 	if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
 		goto fail;
 
-	on_rq = p->se.on_rq;
-	if (on_rq)
+	/*
+	 * If we're not on a rq, the next wake-up will ensure we're
+	 * placed properly.
+	 */
+	if (p->se.on_rq) {
 		deactivate_task(rq_src, p, 0);
-
-	set_task_cpu(p, dest_cpu);
-	if (on_rq) {
+		set_task_cpu(p, dest_cpu);
 		activate_task(rq_dest, p, 0);
 		check_preempt_curr(rq_dest, p, 0);
 	}
@@ -7273,37 +7321,10 @@ static int __migrate_task_irq(struct task_struct *p, int src_cpu, int dest_cpu)
 static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
 {
 	int dest_cpu;
-	const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(dead_cpu));
 
 again:
-	/* Look for allowed, online CPU in same node. */
-	for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
-		if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
-			goto move;
-
-	/* Any allowed, online CPU? */
-	dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
-	if (dest_cpu < nr_cpu_ids)
-		goto move;
-
-	/* No more Mr. Nice Guy. */
-	if (dest_cpu >= nr_cpu_ids) {
-		cpuset_cpus_allowed_locked(p, &p->cpus_allowed);
-		dest_cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed);
-
-		/*
-		 * Don't tell them about moving exiting tasks or
-		 * kernel threads (both mm NULL), since they never
-		 * leave kernel.
-		 */
-		if (p->mm && printk_ratelimit()) {
-			printk(KERN_INFO "process %d (%s) no "
-			       "longer affine to cpu%d\n",
-			       task_pid_nr(p), p->comm, dead_cpu);
-		}
-	}
+	dest_cpu = select_fallback_rq(dead_cpu, p);
 
-move:
 	/* It can have affinity changed while we were choosing. */
 	if (unlikely(!__migrate_task_irq(p, dead_cpu, dest_cpu)))
 		goto again;
@@ -9668,7 +9689,7 @@ void __init sched_init(void)
 #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
 static inline int preempt_count_equals(int preempt_offset)
 {
-	int nested = preempt_count() & ~PREEMPT_ACTIVE;
+	int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth();
 
 	return (nested == PREEMPT_INATOMIC_BASE + preempt_offset);
 }
@@ -10083,7 +10104,7 @@ void sched_move_task(struct task_struct *tsk)
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
 	if (tsk->sched_class->moved_group)
-		tsk->sched_class->moved_group(tsk);
+		tsk->sched_class->moved_group(tsk, on_rq);
 #endif
 
 	if (unlikely(running))