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

Pull scheduler fixes from Ingo Molnar.

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Remove NULL assignment of dattr_cur
  sched: Remove the last NULL entry from sched_feat_names
  sched: Make sched_feat_names const
  sched/rt: Fix SCHED_RR across cgroups
  sched: Move nr_cpus_allowed out of 'struct sched_rt_entity'
  sched: Make sure to not re-read variables after validation
  sched: Fix SD_OVERLAP
  sched: Don't try allocating memory from offline nodes
  sched/nohz: Fix rq->cpu_load calculations some more
  sched/x86: Use cpu_llc_shared_mask(cpu) for coregroup_mask

4 files changed, 115 insertions, 47 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 39eb6011bc38..c46958e26121 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -142,9 +142,8 @@ const_debug unsigned int sysctl_sched_features =
 #define SCHED_FEAT(name, enabled)       \
         #name ,
 
-static __read_mostly char *sched_feat_names[] = {
+static const char * const sched_feat_names[] = {
 #include "features.h"
-        NULL
 };
 
 #undef SCHED_FEAT
@@ -2517,25 +2516,32 @@ static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
         sched_avg_update(this_rq);
 }
 
+#ifdef CONFIG_NO_HZ
+/*
+ * There is no sane way to deal with nohz on smp when using jiffies because the
+ * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading
+ * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}.
+ *
+ * Therefore we cannot use the delta approach from the regular tick since that
+ * would seriously skew the load calculation. However we'll make do for those
+ * updates happening while idle (nohz_idle_balance) or coming out of idle
+ * (tick_nohz_idle_exit).
+ *
+ * This means we might still be one tick off for nohz periods.
+ */
+
 /*
  * Called from nohz_idle_balance() to update the load ratings before doing the
  * idle balance.
  */
 void update_idle_cpu_load(struct rq *this_rq)
 {
-        unsigned long curr_jiffies = jiffies;
+        unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
         unsigned long load = this_rq->load.weight;
         unsigned long pending_updates;
 
         /*
-         * Bloody broken means of dealing with nohz, but better than nothing..
-         * jiffies is updated by one cpu, another cpu can drift wrt the jiffy
-         * update and see 0 difference the one time and 2 the next, even though
-         * we ticked at roughtly the same rate.
-         *
-         * Hence we only use this from nohz_idle_balance() and skip this
-         * nonsense when called from the scheduler_tick() since that's
-         * guaranteed a stable rate.
+         * bail if there's load or we're actually up-to-date.
          */
         if (load || curr_jiffies == this_rq->last_load_update_tick)
                 return;
@@ -2547,12 +2553,38 @@ void update_idle_cpu_load(struct rq *this_rq)
 }
 
 /*
+ * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
+ */
+void update_cpu_load_nohz(void)
+{
+        struct rq *this_rq = this_rq();
+        unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
+        unsigned long pending_updates;
+
+        if (curr_jiffies == this_rq->last_load_update_tick)
+                return;
+
+        raw_spin_lock(&this_rq->lock);
+        pending_updates = curr_jiffies - this_rq->last_load_update_tick;
+        if (pending_updates) {
+                this_rq->last_load_update_tick = curr_jiffies;
+                /*
+                 * We were idle, this means load 0, the current load might be
+                 * !0 due to remote wakeups and the sort.
+                 */
+                __update_cpu_load(this_rq, 0, pending_updates);
+        }
+        raw_spin_unlock(&this_rq->lock);
+}
+#endif /* CONFIG_NO_HZ */
+
+/*
  * Called from scheduler_tick()
  */
 static void update_cpu_load_active(struct rq *this_rq)
 {
         /*
-         * See the mess in update_idle_cpu_load().
+         * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
          */
         this_rq->last_load_update_tick = jiffies;
         __update_cpu_load(this_rq, this_rq->load.weight, 1);
@@ -4982,7 +5014,7 @@ void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
                 p->sched_class->set_cpus_allowed(p, new_mask);
 
         cpumask_copy(&p->cpus_allowed, new_mask);
-        p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
+        p->nr_cpus_allowed = cpumask_weight(new_mask);
 }
 
 /*
@@ -5997,11 +6029,14 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
 
                 cpumask_or(covered, covered, sg_span);
 
-                sg->sgp = *per_cpu_ptr(sdd->sgp, cpumask_first(sg_span));
+                sg->sgp = *per_cpu_ptr(sdd->sgp, i);
                 atomic_inc(&sg->sgp->ref);
 
-                if (cpumask_test_cpu(cpu, sg_span))
+                if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
+                               cpumask_first(sg_span) == cpu) {
+                        WARN_ON_ONCE(!cpumask_test_cpu(cpu, sg_span));
                         groups = sg;
+                }
 
                 if (!first)
                         first = sg;
@@ -6403,7 +6438,7 @@ static void sched_init_numa(void)
                         return;
 
                 for (j = 0; j < nr_node_ids; j++) {
-                        struct cpumask *mask = kzalloc_node(cpumask_size(), GFP_KERNEL, j);
+                        struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
                         if (!mask)
                                 return;
 
@@ -6691,7 +6726,6 @@ static int init_sched_domains(const struct cpumask *cpu_map)
         if (!doms_cur)
                 doms_cur = &fallback_doms;
         cpumask_andnot(doms_cur[0], cpu_map, cpu_isolated_map);
-        dattr_cur = NULL;
         err = build_sched_domains(doms_cur[0], NULL);
         register_sched_domain_sysctl();
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 940e6d17cf96..b2a2d236f27b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2703,7 +2703,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
         int want_sd = 1;
         int sync = wake_flags & WF_SYNC;
 
-        if (p->rt.nr_cpus_allowed == 1)
+        if (p->nr_cpus_allowed == 1)
                 return prev_cpu;
 
         if (sd_flag & SD_BALANCE_WAKE) {
@@ -3503,15 +3503,22 @@ unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
 unsigned long scale_rt_power(int cpu)
 {
         struct rq *rq = cpu_rq(cpu);
-        u64 total, available;
+        u64 total, available, age_stamp, avg;
 
-        total = sched_avg_period() + (rq->clock - rq->age_stamp);
+        /*
+         * Since we're reading these variables without serialization make sure
+         * we read them once before doing sanity checks on them.
+         */
+        age_stamp = ACCESS_ONCE(rq->age_stamp);
+        avg = ACCESS_ONCE(rq->rt_avg);
+
+        total = sched_avg_period() + (rq->clock - age_stamp);
 
-        if (unlikely(total < rq->rt_avg)) {
+        if (unlikely(total < avg)) {
                 /* Ensures that power won't end up being negative */
                 available = 0;
         } else {
-                available = total - rq->rt_avg;
+                available = total - avg;
         }
 
         if (unlikely((s64)total < SCHED_POWER_SCALE))
@@ -3574,11 +3581,26 @@ void update_group_power(struct sched_domain *sd, int cpu)
 
         power = 0;
 
-        group = child->groups;
-        do {
-                power += group->sgp->power;
-                group = group->next;
-        } while (group != child->groups);
+        if (child->flags & SD_OVERLAP) {
+                /*
+                 * SD_OVERLAP domains cannot assume that child groups
+                 * span the current group.
+                 */
+
+                for_each_cpu(cpu, sched_group_cpus(sdg))
+                        power += power_of(cpu);
+        } else  {
+                /*
+                 * !SD_OVERLAP domains can assume that child groups
+                 * span the current group.
+                 */ 
+
+                group = child->groups;
+                do {
+                        power += group->sgp->power;
+                        group = group->next;
+                } while (group != child->groups);
+        }
 
         sdg->sgp->power = power;
 }
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index c5565c3c515f..2a4e8dffbd6b 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -274,13 +274,16 @@ static void update_rt_migration(struct rt_rq *rt_rq)
 
 static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 {
+        struct task_struct *p;
+
         if (!rt_entity_is_task(rt_se))
                 return;
 
+        p = rt_task_of(rt_se);
         rt_rq = &rq_of_rt_rq(rt_rq)->rt;
 
         rt_rq->rt_nr_total++;
-        if (rt_se->nr_cpus_allowed > 1)
+        if (p->nr_cpus_allowed > 1)
                 rt_rq->rt_nr_migratory++;
 
         update_rt_migration(rt_rq);
@@ -288,13 +291,16 @@ static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 
 static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 {
+        struct task_struct *p;
+
         if (!rt_entity_is_task(rt_se))
                 return;
 
+        p = rt_task_of(rt_se);
         rt_rq = &rq_of_rt_rq(rt_rq)->rt;
 
         rt_rq->rt_nr_total--;
-        if (rt_se->nr_cpus_allowed > 1)
+        if (p->nr_cpus_allowed > 1)
                 rt_rq->rt_nr_migratory--;
 
         update_rt_migration(rt_rq);
@@ -1161,7 +1167,7 @@ enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
 
         enqueue_rt_entity(rt_se, flags & ENQUEUE_HEAD);
 
-        if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
+        if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
                 enqueue_pushable_task(rq, p);
 
         inc_nr_running(rq);
@@ -1225,7 +1231,7 @@ select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
 
         cpu = task_cpu(p);
 
-        if (p->rt.nr_cpus_allowed == 1)
+        if (p->nr_cpus_allowed == 1)
                 goto out;
 
         /* For anything but wake ups, just return the task_cpu */
@@ -1260,9 +1266,9 @@ select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
          * will have to sort it out.
          */
         if (curr && unlikely(rt_task(curr)) &&
-            (curr->rt.nr_cpus_allowed < 2 ||
+            (curr->nr_cpus_allowed < 2 ||
              curr->prio <= p->prio) &&
-            (p->rt.nr_cpus_allowed > 1)) {
+            (p->nr_cpus_allowed > 1)) {
                 int target = find_lowest_rq(p);
 
                 if (target != -1)
@@ -1276,10 +1282,10 @@ out:
 
 static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
 {
-        if (rq->curr->rt.nr_cpus_allowed == 1)
+        if (rq->curr->nr_cpus_allowed == 1)
                 return;
 
-        if (p->rt.nr_cpus_allowed != 1
+        if (p->nr_cpus_allowed != 1
             && cpupri_find(&rq->rd->cpupri, p, NULL))
                 return;
 
@@ -1395,7 +1401,7 @@ static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
          * The previous task needs to be made eligible for pushing
          * if it is still active
          */
-        if (on_rt_rq(&p->rt) && p->rt.nr_cpus_allowed > 1)
+        if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
                 enqueue_pushable_task(rq, p);
 }
 
@@ -1408,7 +1414,7 @@ static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
 {
         if (!task_running(rq, p) &&
             (cpu < 0 || cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) &&
-            (p->rt.nr_cpus_allowed > 1))
+            (p->nr_cpus_allowed > 1))
                 return 1;
         return 0;
 }
@@ -1464,7 +1470,7 @@ static int find_lowest_rq(struct task_struct *task)
         if (unlikely(!lowest_mask))
                 return -1;
 
-        if (task->rt.nr_cpus_allowed == 1)
+        if (task->nr_cpus_allowed == 1)
                 return -1; /* No other targets possible */
 
         if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
@@ -1586,7 +1592,7 @@ static struct task_struct *pick_next_pushable_task(struct rq *rq)
 
         BUG_ON(rq->cpu != task_cpu(p));
         BUG_ON(task_current(rq, p));
-        BUG_ON(p->rt.nr_cpus_allowed <= 1);
+        BUG_ON(p->nr_cpus_allowed <= 1);
 
         BUG_ON(!p->on_rq);
         BUG_ON(!rt_task(p));
@@ -1793,9 +1799,9 @@ static void task_woken_rt(struct rq *rq, struct task_struct *p)
         if (!task_running(rq, p) &&
             !test_tsk_need_resched(rq->curr) &&
             has_pushable_tasks(rq) &&
-            p->rt.nr_cpus_allowed > 1 &&
+            p->nr_cpus_allowed > 1 &&
             rt_task(rq->curr) &&
-            (rq->curr->rt.nr_cpus_allowed < 2 ||
+            (rq->curr->nr_cpus_allowed < 2 ||
              rq->curr->prio <= p->prio))
                 push_rt_tasks(rq);
 }
@@ -1817,7 +1823,7 @@ static void set_cpus_allowed_rt(struct task_struct *p,
          * Only update if the process changes its state from whether it
          * can migrate or not.
          */
-        if ((p->rt.nr_cpus_allowed > 1) == (weight > 1))
+        if ((p->nr_cpus_allowed > 1) == (weight > 1))
                 return;
 
         rq = task_rq(p);
@@ -1979,6 +1985,8 @@ static void watchdog(struct rq *rq, struct task_struct *p)
 
 static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
 {
+        struct sched_rt_entity *rt_se = &p->rt;
+
         update_curr_rt(rq);
 
         watchdog(rq, p);
@@ -1996,12 +2004,15 @@ static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
         p->rt.time_slice = RR_TIMESLICE;
 
         /*
-         * Requeue to the end of queue if we are not the only element
-         * on the queue:
+         * Requeue to the end of queue if we (and all of our ancestors) are the
+         * only element on the queue
          */
-        if (p->rt.run_list.prev != p->rt.run_list.next) {
-                requeue_task_rt(rq, p, 0);
-                set_tsk_need_resched(p);
+        for_each_sched_rt_entity(rt_se) {
+                if (rt_se->run_list.prev != rt_se->run_list.next) {
+                        requeue_task_rt(rq, p, 0);
+                        set_tsk_need_resched(p);
+                        return;
+                }
         }
 }
 
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index efd386667536..da70c6db496c 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -576,6 +576,7 @@ void tick_nohz_idle_exit(void)
         /* Update jiffies first */
         select_nohz_load_balancer(0);
         tick_do_update_jiffies64(now);
+        update_cpu_load_nohz();
 
 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
         /*