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, cgroup: Use exit hook to avoid use-after-free crash
  sched: Fix signed unsigned comparison in check_preempt_tick()
  sched: Replace rq->bkl_count with rq->rq_sched_info.bkl_count
  sched, autogroup: Fix CONFIG_RT_GROUP_SCHED sched_setscheduler() failure
  sched: Display autogroup names in /proc/sched_debug
  sched: Reinstate group names in /proc/sched_debug
  sched: Update effective_load() to use global share weights

5 files changed, 117 insertions, 22 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index ea3e5eff3878..18d38e4ec7ba 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -553,9 +553,6 @@ struct rq {
         /* try_to_wake_up() stats */
         unsigned int ttwu_count;
         unsigned int ttwu_local;
-
-        /* BKL stats */
-        unsigned int bkl_count;
 #endif
 };
 
@@ -609,6 +606,9 @@ static inline struct task_group *task_group(struct task_struct *p)
         struct task_group *tg;
         struct cgroup_subsys_state *css;
 
+        if (p->flags & PF_EXITING)
+                return &root_task_group;
+
         css = task_subsys_state_check(p, cpu_cgroup_subsys_id,
                         lockdep_is_held(&task_rq(p)->lock));
         tg = container_of(css, struct task_group, css);
@@ -3887,7 +3887,7 @@ static inline void schedule_debug(struct task_struct *prev)
         schedstat_inc(this_rq(), sched_count);
 #ifdef CONFIG_SCHEDSTATS
         if (unlikely(prev->lock_depth >= 0)) {
-                schedstat_inc(this_rq(), bkl_count);
+                schedstat_inc(this_rq(), rq_sched_info.bkl_count);
                 schedstat_inc(prev, sched_info.bkl_count);
         }
 #endif
@@ -4871,7 +4871,8 @@ recheck:
                  * assigned.
                  */
                 if (rt_bandwidth_enabled() && rt_policy(policy) &&
-                                task_group(p)->rt_bandwidth.rt_runtime == 0) {
+                                task_group(p)->rt_bandwidth.rt_runtime == 0 &&
+                                !task_group_is_autogroup(task_group(p))) {
                         __task_rq_unlock(rq);
                         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
                         return -EPERM;
@@ -8882,6 +8883,20 @@ cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
         }
 }
 
+static void
+cpu_cgroup_exit(struct cgroup_subsys *ss, struct task_struct *task)
+{
+        /*
+         * cgroup_exit() is called in the copy_process() failure path.
+         * Ignore this case since the task hasn't ran yet, this avoids
+         * trying to poke a half freed task state from generic code.
+         */
+        if (!(task->flags & PF_EXITING))
+                return;
+
+        sched_move_task(task);
+}
+
 #ifdef CONFIG_FAIR_GROUP_SCHED
 static int cpu_shares_write_u64(struct cgroup *cgrp, struct cftype *cftype,
                                 u64 shareval)
@@ -8954,6 +8969,7 @@ struct cgroup_subsys cpu_cgroup_subsys = {
         .destroy        = cpu_cgroup_destroy,
         .can_attach     = cpu_cgroup_can_attach,
         .attach         = cpu_cgroup_attach,
+        .exit           = cpu_cgroup_exit,
         .populate       = cpu_cgroup_populate,
         .subsys_id      = cpu_cgroup_subsys_id,
         .early_init     = 1,
diff --git a/kernel/sched_autogroup.c b/kernel/sched_autogroup.c
index 32a723b8f84c..9fb656283157 100644
--- a/kernel/sched_autogroup.c
+++ b/kernel/sched_autogroup.c
@@ -27,6 +27,11 @@ static inline void autogroup_destroy(struct kref *kref)
 {
         struct autogroup *ag = container_of(kref, struct autogroup, kref);
 
+#ifdef CONFIG_RT_GROUP_SCHED
+        /* We've redirected RT tasks to the root task group... */
+        ag->tg->rt_se = NULL;
+        ag->tg->rt_rq = NULL;
+#endif
         sched_destroy_group(ag->tg);
 }
 
@@ -55,6 +60,10 @@ static inline struct autogroup *autogroup_task_get(struct task_struct *p)
         return ag;
 }
 
+#ifdef CONFIG_RT_GROUP_SCHED
+static void free_rt_sched_group(struct task_group *tg);
+#endif
+
 static inline struct autogroup *autogroup_create(void)
 {
         struct autogroup *ag = kzalloc(sizeof(*ag), GFP_KERNEL);
@@ -72,6 +81,19 @@ static inline struct autogroup *autogroup_create(void)
         init_rwsem(&ag->lock);
         ag->id = atomic_inc_return(&autogroup_seq_nr);
         ag->tg = tg;
+#ifdef CONFIG_RT_GROUP_SCHED
+        /*
+         * Autogroup RT tasks are redirected to the root task group
+         * so we don't have to move tasks around upon policy change,
+         * or flail around trying to allocate bandwidth on the fly.
+         * A bandwidth exception in __sched_setscheduler() allows
+         * the policy change to proceed.  Thereafter, task_group()
+         * returns &root_task_group, so zero bandwidth is required.
+         */
+        free_rt_sched_group(tg);
+        tg->rt_se = root_task_group.rt_se;
+        tg->rt_rq = root_task_group.rt_rq;
+#endif
         tg->autogroup = ag;
 
         return ag;
@@ -106,6 +128,11 @@ task_wants_autogroup(struct task_struct *p, struct task_group *tg)
         return true;
 }
 
+static inline bool task_group_is_autogroup(struct task_group *tg)
+{
+        return tg != &root_task_group && tg->autogroup;
+}
+
 static inline struct task_group *
 autogroup_task_group(struct task_struct *p, struct task_group *tg)
 {
@@ -231,6 +258,11 @@ void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m)
 #ifdef CONFIG_SCHED_DEBUG
 static inline int autogroup_path(struct task_group *tg, char *buf, int buflen)
 {
+        int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled);
+
+        if (!enabled || !tg->autogroup)
+                return 0;
+
         return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id);
 }
 #endif /* CONFIG_SCHED_DEBUG */
diff --git a/kernel/sched_autogroup.h b/kernel/sched_autogroup.h
index 5358e241cb20..7b859ffe5dad 100644
--- a/kernel/sched_autogroup.h
+++ b/kernel/sched_autogroup.h
@@ -15,6 +15,10 @@ autogroup_task_group(struct task_struct *p, struct task_group *tg);
 
 static inline void autogroup_init(struct task_struct *init_task) {  }
 static inline void autogroup_free(struct task_group *tg) { }
+static inline bool task_group_is_autogroup(struct task_group *tg)
+{
+        return 0;
+}
 
 static inline struct task_group *
 autogroup_task_group(struct task_struct *p, struct task_group *tg)
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index 1dfae3d014b5..eb6cb8edd075 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -16,6 +16,8 @@
 #include <linux/kallsyms.h>
 #include <linux/utsname.h>
 
+static DEFINE_SPINLOCK(sched_debug_lock);
+
 /*
  * This allows printing both to /proc/sched_debug and
  * to the console
@@ -86,6 +88,26 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
 }
 #endif
 
+#ifdef CONFIG_CGROUP_SCHED
+static char group_path[PATH_MAX];
+
+static char *task_group_path(struct task_group *tg)
+{
+        if (autogroup_path(tg, group_path, PATH_MAX))
+                return group_path;
+
+        /*
+         * May be NULL if the underlying cgroup isn't fully-created yet
+         */
+        if (!tg->css.cgroup) {
+                group_path[0] = '\0';
+                return group_path;
+        }
+        cgroup_path(tg->css.cgroup, group_path, PATH_MAX);
+        return group_path;
+}
+#endif
+
 static void
 print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
 {
@@ -108,6 +130,9 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
         SEQ_printf(m, "%15Ld %15Ld %15Ld.%06ld %15Ld.%06ld %15Ld.%06ld",
                 0LL, 0LL, 0LL, 0L, 0LL, 0L, 0LL, 0L);
 #endif
+#ifdef CONFIG_CGROUP_SCHED
+        SEQ_printf(m, " %s", task_group_path(task_group(p)));
+#endif
 
         SEQ_printf(m, "\n");
 }
@@ -144,7 +169,11 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
         struct sched_entity *last;
         unsigned long flags;
 
+#ifdef CONFIG_FAIR_GROUP_SCHED
+        SEQ_printf(m, "\ncfs_rq[%d]:%s\n", cpu, task_group_path(cfs_rq->tg));
+#else
         SEQ_printf(m, "\ncfs_rq[%d]:\n", cpu);
+#endif
         SEQ_printf(m, "  .%-30s: %Ld.%06ld\n", "exec_clock",
                         SPLIT_NS(cfs_rq->exec_clock));
 
@@ -191,7 +220,11 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
 
 void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq)
 {
+#ifdef CONFIG_RT_GROUP_SCHED
+        SEQ_printf(m, "\nrt_rq[%d]:%s\n", cpu, task_group_path(rt_rq->tg));
+#else
         SEQ_printf(m, "\nrt_rq[%d]:\n", cpu);
+#endif
 
 #define P(x) \
         SEQ_printf(m, "  .%-30s: %Ld\n", #x, (long long)(rt_rq->x))
@@ -212,6 +245,7 @@ extern __read_mostly int sched_clock_running;
 static void print_cpu(struct seq_file *m, int cpu)
 {
         struct rq *rq = cpu_rq(cpu);
+        unsigned long flags;
 
 #ifdef CONFIG_X86
         {
@@ -262,14 +296,20 @@ static void print_cpu(struct seq_file *m, int cpu)
         P(ttwu_count);
         P(ttwu_local);
 
-        P(bkl_count);
+        SEQ_printf(m, "  .%-30s: %d\n", "bkl_count",
+                                rq->rq_sched_info.bkl_count);
 
 #undef P
+#undef P64
 #endif
+        spin_lock_irqsave(&sched_debug_lock, flags);
         print_cfs_stats(m, cpu);
         print_rt_stats(m, cpu);
 
+        rcu_read_lock();
         print_rq(m, rq, cpu);
+        rcu_read_unlock();
+        spin_unlock_irqrestore(&sched_debug_lock, flags);
 }
 
 static const char *sched_tunable_scaling_names[] = {
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index c62ebae65cf0..77e9166d7bbf 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1062,6 +1062,9 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
                 struct sched_entity *se = __pick_next_entity(cfs_rq);
                 s64 delta = curr->vruntime - se->vruntime;
 
+                if (delta < 0)
+                        return;
+
                 if (delta > ideal_runtime)
                         resched_task(rq_of(cfs_rq)->curr);
         }
@@ -1362,27 +1365,27 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
                 return wl;
 
         for_each_sched_entity(se) {
-                long S, rw, s, a, b;
+                long lw, w;
 
-                S = se->my_q->tg->shares;
-                s = se->load.weight;
-                rw = se->my_q->load.weight;
+                tg = se->my_q->tg;
+                w = se->my_q->load.weight;
 
-                a = S*(rw + wl);
-                b = S*rw + s*wg;
+                /* use this cpu's instantaneous contribution */
+                lw = atomic_read(&tg->load_weight);
+                lw -= se->my_q->load_contribution;
+                lw += w + wg;
 
-                wl = s*(a-b);
+                wl += w;
 
-                if (likely(b))
-                        wl /= b;
+                if (lw > 0 && wl < lw)
+                        wl = (wl * tg->shares) / lw;
+                else
+                        wl = tg->shares;
 
-                /*
-                 * Assume the group is already running and will
-                 * thus already be accounted for in the weight.
-                 *
-                 * That is, moving shares between CPUs, does not
-                 * alter the group weight.
-                 */
+                /* zero point is MIN_SHARES */
+                if (wl < MIN_SHARES)
+                        wl = MIN_SHARES;
+                wl -= se->load.weight;
                 wg = 0;
         }