Merge commit 'v2.6.26-rc8' into core/softlockup

7 files changed, 164 insertions, 64 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 039baa4cd90c..9fceb97e989c 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1037,8 +1037,8 @@ int current_cpuset_is_being_rebound(void)
 
 static int update_relax_domain_level(struct cpuset *cs, s64 val)
 {
-        if ((int)val < 0)
-                val = -1;
+        if (val < -1 || val >= SD_LV_MAX)
+                return -EINVAL;
 
         if (val != cs->relax_domain_level) {
                 cs->relax_domain_level = val;
@@ -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/futex.c b/kernel/futex.c
index 449def8074fe..7d1136e97c14 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1096,21 +1096,64 @@ static void unqueue_me_pi(struct futex_q *q)
  * private futexes.
  */
 static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
-                                struct task_struct *newowner)
+                                struct task_struct *newowner,
+                                struct rw_semaphore *fshared)
 {
         u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
         struct futex_pi_state *pi_state = q->pi_state;
+        struct task_struct *oldowner = pi_state->owner;
         u32 uval, curval, newval;
-        int ret;
+        int ret, attempt = 0;
 
         /* Owner died? */
+        if (!pi_state->owner)
+                newtid |= FUTEX_OWNER_DIED;
+
+        /*
+         * We are here either because we stole the rtmutex from the
+         * pending owner or we are the pending owner which failed to
+         * get the rtmutex. We have to replace the pending owner TID
+         * in the user space variable. This must be atomic as we have
+         * to preserve the owner died bit here.
+         *
+         * Note: We write the user space value _before_ changing the
+         * pi_state because we can fault here. Imagine swapped out
+         * pages or a fork, which was running right before we acquired
+         * mmap_sem, that marked all the anonymous memory readonly for
+         * cow.
+         *
+         * Modifying pi_state _before_ the user space value would
+         * leave the pi_state in an inconsistent state when we fault
+         * here, because we need to drop the hash bucket lock to
+         * handle the fault. This might be observed in the PID check
+         * in lookup_pi_state.
+         */
+retry:
+        if (get_futex_value_locked(&uval, uaddr))
+                goto handle_fault;
+
+        while (1) {
+                newval = (uval & FUTEX_OWNER_DIED) | newtid;
+
+                curval = cmpxchg_futex_value_locked(uaddr, uval, newval);
+
+                if (curval == -EFAULT)
+                        goto handle_fault;
+                if (curval == uval)
+                        break;
+                uval = curval;
+        }
+
+        /*
+         * We fixed up user space. Now we need to fix the pi_state
+         * itself.
+         */
         if (pi_state->owner != NULL) {
                 spin_lock_irq(&pi_state->owner->pi_lock);
                 WARN_ON(list_empty(&pi_state->list));
                 list_del_init(&pi_state->list);
                 spin_unlock_irq(&pi_state->owner->pi_lock);
-        } else
-                newtid |= FUTEX_OWNER_DIED;
+        }
 
         pi_state->owner = newowner;
 
@@ -1118,26 +1161,35 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
         WARN_ON(!list_empty(&pi_state->list));
         list_add(&pi_state->list, &newowner->pi_state_list);
         spin_unlock_irq(&newowner->pi_lock);
+        return 0;
 
         /*
-         * We own it, so we have to replace the pending owner
-         * TID. This must be atomic as we have preserve the
-         * owner died bit here.
+         * To handle the page fault we need to drop the hash bucket
+         * lock here. That gives the other task (either the pending
+         * owner itself or the task which stole the rtmutex) the
+         * chance to try the fixup of the pi_state. So once we are
+         * back from handling the fault we need to check the pi_state
+         * after reacquiring the hash bucket lock and before trying to
+         * do another fixup. When the fixup has been done already we
+         * simply return.
          */
-        ret = get_futex_value_locked(&uval, uaddr);
+handle_fault:
+        spin_unlock(q->lock_ptr);
 
-        while (!ret) {
-                newval = (uval & FUTEX_OWNER_DIED) | newtid;
+        ret = futex_handle_fault((unsigned long)uaddr, fshared, attempt++);
 
-                curval = cmpxchg_futex_value_locked(uaddr, uval, newval);
+        spin_lock(q->lock_ptr);
 
-                if (curval == -EFAULT)
-                        ret = -EFAULT;
-                if (curval == uval)
-                        break;
-                uval = curval;
-        }
-        return ret;
+        /*
+         * Check if someone else fixed it for us:
+         */
+        if (pi_state->owner != oldowner)
+                return 0;
+
+        if (ret)
+                return ret;
+
+        goto retry;
 }
 
 /*
@@ -1507,7 +1559,7 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
                  * that case:
                  */
                 if (q.pi_state->owner != curr)
-                        ret = fixup_pi_state_owner(uaddr, &q, curr);
+                        ret = fixup_pi_state_owner(uaddr, &q, curr, fshared);
         } else {
                 /*
                  * Catch the rare case, where the lock was released
@@ -1539,7 +1591,8 @@ static int futex_lock_pi(u32 __user *uaddr, struct rw_semaphore *fshared,
                                 int res;
 
                                 owner = rt_mutex_owner(&q.pi_state->pi_mutex);
-                                res = fixup_pi_state_owner(uaddr, &q, owner);
+                                res = fixup_pi_state_owner(uaddr, &q, owner,
+                                                           fshared);
 
                                 /* propagate -EFAULT, if the fixup failed */
                                 if (res)
diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index 79e3c90113c2..3ec23c3ec97f 100644
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -1499,7 +1499,8 @@ int kgdb_nmicallback(int cpu, void *regs)
         return 1;
 }
 
-void kgdb_console_write(struct console *co, const char *s, unsigned count)
+static void kgdb_console_write(struct console *co, const char *s,
+   unsigned count)
 {
         unsigned long flags;
 
diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c
index e1cdf196a515..5e02b7740702 100644
--- a/kernel/rcupreempt.c
+++ b/kernel/rcupreempt.c
@@ -217,8 +217,6 @@ long rcu_batches_completed(void)
 }
 EXPORT_SYMBOL_GPL(rcu_batches_completed);
 
-EXPORT_SYMBOL_GPL(rcu_batches_completed_bh);
-
 void __rcu_read_lock(void)
 {
         int idx;
diff --git a/kernel/sched.c b/kernel/sched.c
index eaf6751e7612..3aaa5c8cb421 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)
 {
@@ -4396,22 +4398,20 @@ do_wait_for_common(struct completion *x, long timeout, int state)
                              signal_pending(current)) ||
                             (state == TASK_KILLABLE &&
                              fatal_signal_pending(current))) {
-                                __remove_wait_queue(&x->wait, &wait);
-                                return -ERESTARTSYS;
+                                timeout = -ERESTARTSYS;
+                                break;
                         }
                         __set_current_state(state);
                         spin_unlock_irq(&x->wait.lock);
                         timeout = schedule_timeout(timeout);
                         spin_lock_irq(&x->wait.lock);
-                        if (!timeout) {
-                                __remove_wait_queue(&x->wait, &wait);
-                                return timeout;
-                        }
-                } while (!x->done);
+                } while (!x->done && timeout);
                 __remove_wait_queue(&x->wait, &wait);
+                if (!x->done)
+                        return timeout;
         }
         x->done--;
-        return timeout;
+        return timeout ?: 1;
 }
 
 static long __sched
@@ -6877,7 +6877,12 @@ static int default_relax_domain_level = -1;
 
 static int __init setup_relax_domain_level(char *str)
 {
-        default_relax_domain_level = simple_strtoul(str, NULL, 0);
+        unsigned long val;
+
+        val = simple_strtoul(str, NULL, 0);
+        if (val < SD_LV_MAX)
+                default_relax_domain_level = val;
+
         return 1;
 }
 __setup("relax_domain_level=", setup_relax_domain_level);
@@ -7236,6 +7241,18 @@ 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 +7399,7 @@ 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 +7485,7 @@ 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 +7504,16 @@ 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 +7653,6 @@ 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 +8374,7 @@ 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..0f3c19197fa4 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -250,7 +250,8 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
                         if (rt_rq->rt_time || rt_rq->rt_nr_running)
                                 idle = 0;
                         spin_unlock(&rt_rq->rt_runtime_lock);
-                }
+                } else if (rt_rq->rt_nr_running)
+                        idle = 0;
 
                 if (enqueue)
                         sched_rt_rq_enqueue(rt_rq);
@@ -449,13 +450,19 @@ 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 +471,7 @@ 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 +487,10 @@ 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 +498,26 @@ 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 +531,15 @@ 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 +550,10 @@ 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);
 }
 
 /*