Merge branch 'perf/urgent' into perf/core

So that we can get the perf bench exec stack fixes and then apply the
remaining fix for the files added after what is in perf/urgent.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

8 files changed, 106 insertions, 18 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 294b1709170d..4b4042f9bc6a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1038,6 +1038,22 @@ void do_exit(long code)
         if (tsk->nr_dirtied)
                 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
         exit_rcu();
+
+        /*
+         * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
+         * when the following two conditions become true.
+         *   - There is race condition of mmap_sem (It is acquired by
+         *     exit_mm()), and
+         *   - SMI occurs before setting TASK_RUNINNG.
+         *     (or hypervisor of virtual machine switches to other guest)
+         *  As a result, we may become TASK_RUNNING after becoming TASK_DEAD
+         *
+         * To avoid it, we have to wait for releasing tsk->pi_lock which
+         * is held by try_to_wake_up()
+         */
+        smp_mb();
+        raw_spin_unlock_wait(&tsk->pi_lock);
+
         /* causes final put_task_struct in finish_task_switch(). */
         tsk->state = TASK_DEAD;
         tsk->flags |= PF_NOFREEZE;      /* tell freezer to ignore us */
diff --git a/kernel/fork.c b/kernel/fork.c
index 051f090d40c1..1b2ef3c23ae4 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -647,6 +647,26 @@ struct mm_struct *get_task_mm(struct task_struct *task)
 }
 EXPORT_SYMBOL_GPL(get_task_mm);
 
+struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
+{
+        struct mm_struct *mm;
+        int err;
+
+        err =  mutex_lock_killable(&task->signal->cred_guard_mutex);
+        if (err)
+                return ERR_PTR(err);
+
+        mm = get_task_mm(task);
+        if (mm && mm != current->mm &&
+                        !ptrace_may_access(task, mode)) {
+                mmput(mm);
+                mm = ERR_PTR(-EACCES);
+        }
+        mutex_unlock(&task->signal->cred_guard_mutex);
+
+        return mm;
+}
+
 /* Please note the differences between mmput and mm_release.
  * mmput is called whenever we stop holding onto a mm_struct,
  * error success whatever.
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 77274c9ba2f1..eeca00311f39 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -188,3 +188,22 @@ void thaw_processes(void)
         printk("done.\n");
 }
 
+void thaw_kernel_threads(void)
+{
+        struct task_struct *g, *p;
+
+        pm_nosig_freezing = false;
+        printk("Restarting kernel threads ... ");
+
+        thaw_workqueues();
+
+        read_lock(&tasklist_lock);
+        do_each_thread(g, p) {
+                if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
+                        __thaw_task(p);
+        } while_each_thread(g, p);
+        read_unlock(&tasklist_lock);
+
+        schedule();
+        printk("done.\n");
+}
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 6b1ab7a88522..e5a21a857302 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -274,6 +274,15 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
                 swsusp_free();
                 memset(&data->handle, 0, sizeof(struct snapshot_handle));
                 data->ready = 0;
+                /*
+                 * It is necessary to thaw kernel threads here, because
+                 * SNAPSHOT_CREATE_IMAGE may be invoked directly after
+                 * SNAPSHOT_FREE.  In that case, if kernel threads were not
+                 * thawed, the preallocation of memory carried out by
+                 * hibernation_snapshot() might run into problems (i.e. it
+                 * might fail or even deadlock).
+                 */
+                thaw_kernel_threads();
                 break;
 
         case SNAPSHOT_PREF_IMAGE_SIZE:
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index df00cb09263e..5255c9d2e053 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -74,6 +74,7 @@
 
 #include <asm/tlb.h>
 #include <asm/irq_regs.h>
+#include <asm/mutex.h>
 #ifdef CONFIG_PARAVIRT
 #include <asm/paravirt.h>
 #endif
@@ -723,9 +724,6 @@ static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
         p->sched_class->dequeue_task(rq, p, flags);
 }
 
-/*
- * activate_task - move a task to the runqueue.
- */
 void activate_task(struct rq *rq, struct task_struct *p, int flags)
 {
         if (task_contributes_to_load(p))
@@ -734,9 +732,6 @@ void activate_task(struct rq *rq, struct task_struct *p, int flags)
         enqueue_task(rq, p, flags);
 }
 
-/*
- * deactivate_task - remove a task from the runqueue.
- */
 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
 {
         if (task_contributes_to_load(p))
@@ -4134,7 +4129,7 @@ recheck:
         on_rq = p->on_rq;
         running = task_current(rq, p);
         if (on_rq)
-                deactivate_task(rq, p, 0);
+                dequeue_task(rq, p, 0);
         if (running)
                 p->sched_class->put_prev_task(rq, p);
 
@@ -4147,7 +4142,7 @@ recheck:
         if (running)
                 p->sched_class->set_curr_task(rq);
         if (on_rq)
-                activate_task(rq, p, 0);
+                enqueue_task(rq, p, 0);
 
         check_class_changed(rq, p, prev_class, oldprio);
         task_rq_unlock(rq, p, &flags);
@@ -4998,9 +4993,9 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
          * placed properly.
          */
         if (p->on_rq) {
-                deactivate_task(rq_src, p, 0);
+                dequeue_task(rq_src, p, 0);
                 set_task_cpu(p, dest_cpu);
-                activate_task(rq_dest, p, 0);
+                enqueue_task(rq_dest, p, 0);
                 check_preempt_curr(rq_dest, p, 0);
         }
 done:
@@ -7032,10 +7027,10 @@ static void normalize_task(struct rq *rq, struct task_struct *p)
 
         on_rq = p->on_rq;
         if (on_rq)
-                deactivate_task(rq, p, 0);
+                dequeue_task(rq, p, 0);
         __setscheduler(rq, p, SCHED_NORMAL, 0);
         if (on_rq) {
-                activate_task(rq, p, 0);
+                enqueue_task(rq, p, 0);
                 resched_task(rq->curr);
         }
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 84adb2d66cbd..7c6414fc669d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4866,6 +4866,15 @@ static void nohz_balancer_kick(int cpu)
         return;
 }
 
+static inline void clear_nohz_tick_stopped(int cpu)
+{
+        if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
+                cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
+                atomic_dec(&nohz.nr_cpus);
+                clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
+        }
+}
+
 static inline void set_cpu_sd_state_busy(void)
 {
         struct sched_domain *sd;
@@ -4904,6 +4913,12 @@ void select_nohz_load_balancer(int stop_tick)
 {
         int cpu = smp_processor_id();
 
+        /*
+         * If this cpu is going down, then nothing needs to be done.
+         */
+        if (!cpu_active(cpu))
+                return;
+
         if (stop_tick) {
                 if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
                         return;
@@ -4914,6 +4929,18 @@ void select_nohz_load_balancer(int stop_tick)
         }
         return;
 }
+
+static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
+                                        unsigned long action, void *hcpu)
+{
+        switch (action & ~CPU_TASKS_FROZEN) {
+        case CPU_DYING:
+                clear_nohz_tick_stopped(smp_processor_id());
+                return NOTIFY_OK;
+        default:
+                return NOTIFY_DONE;
+        }
+}
 #endif
 
 static DEFINE_SPINLOCK(balancing);
@@ -5070,11 +5097,7 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu)
         * busy tick after returning from idle, we will update the busy stats.
         */
         set_cpu_sd_state_busy();
-        if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
-                clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
-                cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
-                atomic_dec(&nohz.nr_cpus);
-        }
+        clear_nohz_tick_stopped(cpu);
 
         /*
          * None are in tickless mode and hence no need for NOHZ idle load
@@ -5590,6 +5613,7 @@ __init void init_sched_fair_class(void)
 
 #ifdef CONFIG_NO_HZ
         zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
+        cpu_notifier(sched_ilb_notifier, 0);
 #endif
 #endif /* SMP */
 
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 3640ebbb466b..f42ae7fb5ec5 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1587,6 +1587,11 @@ static int push_rt_task(struct rq *rq)
         if (!next_task)
                 return 0;
 
+#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
+       if (unlikely(task_running(rq, next_task)))
+               return 0;
+#endif
+
 retry:
         if (unlikely(next_task == rq->curr)) {
                 WARN_ON(1);
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 1d7bca7f4f52..d117262deba3 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -296,7 +296,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
                 if (__this_cpu_read(soft_watchdog_warn) == true)
                         return HRTIMER_RESTART;
 
-                printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
+                printk(KERN_EMERG "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
                         smp_processor_id(), duration,
                         current->comm, task_pid_nr(current));
                 print_modules();