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 d6527ac0f6e7..e507af086b42 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))