Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched, delay accounting: fix incorrect delay time when constantly waiting on runqueue
  sched: CPU hotplug events must not destroy scheduler domains created by the cpusets
  sched: rt-group: fix RR buglet
  sched: rt-group: heirarchy aware throttle
  sched: rt-group: fix hierarchy
  sched: NULL pointer dereference while setting sched_rt_period_us
  sched: fix defined-but-unused warning

4 files changed, 73 insertions, 29 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 039baa4cd90c..bceb89557973 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1890,6 +1890,12 @@ static void common_cpu_mem_hotplug_unplug(void)
         top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
         scan_for_empty_cpusets(&top_cpuset);
 
+        /*
+         * Scheduler destroys domains on hotplug events.
+         * Rebuild them based on the current settings.
+         */
+        rebuild_sched_domains();
+
         cgroup_unlock();
 }
 
diff --git a/kernel/sched.c b/kernel/sched.c
index eaf6751e7612..4a3cb0614158 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1127,6 +1127,7 @@ static enum hrtimer_restart hrtick(struct hrtimer *timer)
         return HRTIMER_NORESTART;
 }
 
+#ifdef CONFIG_SMP
 static void hotplug_hrtick_disable(int cpu)
 {
         struct rq *rq = cpu_rq(cpu);
@@ -1182,6 +1183,7 @@ static void init_hrtick(void)
 {
         hotcpu_notifier(hotplug_hrtick, 0);
 }
+#endif /* CONFIG_SMP */
 
 static void init_rq_hrtick(struct rq *rq)
 {
@@ -7236,6 +7238,18 @@ void __attribute__((weak)) arch_update_cpu_topology(void)
 }
 
 /*
+ * Free current domain masks.
+ * Called after all cpus are attached to NULL domain.
+ */
+static void free_sched_domains(void)
+{
+        ndoms_cur = 0;
+        if (doms_cur != &fallback_doms)
+                kfree(doms_cur);
+        doms_cur = &fallback_doms;
+}
+
+/*
  * Set up scheduler domains and groups. Callers must hold the hotplug lock.
  * For now this just excludes isolated cpus, but could be used to
  * exclude other special cases in the future.
@@ -7382,6 +7396,7 @@ int arch_reinit_sched_domains(void)
         get_online_cpus();
         mutex_lock(&sched_domains_mutex);
         detach_destroy_domains(&cpu_online_map);
+        free_sched_domains();
         err = arch_init_sched_domains(&cpu_online_map);
         mutex_unlock(&sched_domains_mutex);
         put_online_cpus();
@@ -7467,6 +7482,7 @@ static int update_sched_domains(struct notifier_block *nfb,
         case CPU_DOWN_PREPARE:
         case CPU_DOWN_PREPARE_FROZEN:
                 detach_destroy_domains(&cpu_online_map);
+                free_sched_domains();
                 return NOTIFY_OK;
 
         case CPU_UP_CANCELED:
@@ -7485,8 +7501,16 @@ static int update_sched_domains(struct notifier_block *nfb,
                 return NOTIFY_DONE;
         }
 
+#ifndef CONFIG_CPUSETS
+        /*
+         * Create default domain partitioning if cpusets are disabled.
+         * Otherwise we let cpusets rebuild the domains based on the
+         * current setup.
+         */
+
         /* The hotplug lock is already held by cpu_up/cpu_down */
         arch_init_sched_domains(&cpu_online_map);
+#endif
 
         return NOTIFY_OK;
 }
@@ -7626,7 +7650,6 @@ static void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
         else
                 rt_se->rt_rq = parent->my_q;
 
-        rt_se->rt_rq = &rq->rt;
         rt_se->my_q = rt_rq;
         rt_se->parent = parent;
         INIT_LIST_HEAD(&rt_se->run_list);
@@ -8348,7 +8371,7 @@ static unsigned long to_ratio(u64 period, u64 runtime)
 #ifdef CONFIG_CGROUP_SCHED
 static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
 {
-        struct task_group *tgi, *parent = tg->parent;
+        struct task_group *tgi, *parent = tg ? tg->parent : NULL;
         unsigned long total = 0;
 
         if (!parent) {
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 3432d573205d..1dad5bbb59b6 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -449,13 +449,19 @@ void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 #endif
 }
 
-static void enqueue_rt_entity(struct sched_rt_entity *rt_se)
+static void __enqueue_rt_entity(struct sched_rt_entity *rt_se)
 {
         struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
         struct rt_prio_array *array = &rt_rq->active;
         struct rt_rq *group_rq = group_rt_rq(rt_se);
 
-        if (group_rq && rt_rq_throttled(group_rq))
+        /*
+         * Don't enqueue the group if its throttled, or when empty.
+         * The latter is a consequence of the former when a child group
+         * get throttled and the current group doesn't have any other
+         * active members.
+         */
+        if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
                 return;
 
         list_add_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se));
@@ -464,7 +470,7 @@ static void enqueue_rt_entity(struct sched_rt_entity *rt_se)
         inc_rt_tasks(rt_se, rt_rq);
 }
 
-static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
+static void __dequeue_rt_entity(struct sched_rt_entity *rt_se)
 {
         struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
         struct rt_prio_array *array = &rt_rq->active;
@@ -480,11 +486,10 @@ static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
  * Because the prio of an upper entry depends on the lower
  * entries, we must remove entries top - down.
  */
-static void dequeue_rt_stack(struct task_struct *p)
+static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
 {
-        struct sched_rt_entity *rt_se, *back = NULL;
+        struct sched_rt_entity *back = NULL;
 
-        rt_se = &p->rt;
         for_each_sched_rt_entity(rt_se) {
                 rt_se->back = back;
                 back = rt_se;
@@ -492,7 +497,26 @@ static void dequeue_rt_stack(struct task_struct *p)
 
         for (rt_se = back; rt_se; rt_se = rt_se->back) {
                 if (on_rt_rq(rt_se))
-                        dequeue_rt_entity(rt_se);
+                        __dequeue_rt_entity(rt_se);
+        }
+}
+
+static void enqueue_rt_entity(struct sched_rt_entity *rt_se)
+{
+        dequeue_rt_stack(rt_se);
+        for_each_sched_rt_entity(rt_se)
+                __enqueue_rt_entity(rt_se);
+}
+
+static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
+{
+        dequeue_rt_stack(rt_se);
+
+        for_each_sched_rt_entity(rt_se) {
+                struct rt_rq *rt_rq = group_rt_rq(rt_se);
+
+                if (rt_rq && rt_rq->rt_nr_running)
+                        __enqueue_rt_entity(rt_se);
         }
 }
 
@@ -506,32 +530,15 @@ static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
         if (wakeup)
                 rt_se->timeout = 0;
 
-        dequeue_rt_stack(p);
-
-        /*
-         * enqueue everybody, bottom - up.
-         */
-        for_each_sched_rt_entity(rt_se)
-                enqueue_rt_entity(rt_se);
+        enqueue_rt_entity(rt_se);
 }
 
 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int sleep)
 {
         struct sched_rt_entity *rt_se = &p->rt;
-        struct rt_rq *rt_rq;
 
         update_curr_rt(rq);
-
-        dequeue_rt_stack(p);
-
-        /*
-         * re-enqueue all non-empty rt_rq entities.
-         */
-        for_each_sched_rt_entity(rt_se) {
-                rt_rq = group_rt_rq(rt_se);
-                if (rt_rq && rt_rq->rt_nr_running)
-                        enqueue_rt_entity(rt_se);
-        }
+        dequeue_rt_entity(rt_se);
 }
 
 /*
@@ -542,8 +549,10 @@ static
 void requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
 {
         struct rt_prio_array *array = &rt_rq->active;
+        struct list_head *queue = array->queue + rt_se_prio(rt_se);
 
-        list_move_tail(&rt_se->run_list, array->queue + rt_se_prio(rt_se));
+        if (on_rt_rq(rt_se))
+                list_move_tail(&rt_se->run_list, queue);
 }
 
 static void requeue_task_rt(struct rq *rq, struct task_struct *p)
diff --git a/kernel/sched_stats.h b/kernel/sched_stats.h
index a38878e0e49d..80179ef7450e 100644
--- a/kernel/sched_stats.h
+++ b/kernel/sched_stats.h
@@ -198,6 +198,9 @@ static inline void sched_info_queued(struct task_struct *t)
 /*
  * Called when a process ceases being the active-running process, either
  * voluntarily or involuntarily.  Now we can calculate how long we ran.
+ * Also, if the process is still in the TASK_RUNNING state, call
+ * sched_info_queued() to mark that it has now again started waiting on
+ * the runqueue.
  */
 static inline void sched_info_depart(struct task_struct *t)
 {
@@ -206,6 +209,9 @@ static inline void sched_info_depart(struct task_struct *t)
 
         t->sched_info.cpu_time += delta;
         rq_sched_info_depart(task_rq(t), delta);
+
+        if (t->state == TASK_RUNNING)
+                sched_info_queued(t);
 }
 
 /*