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: Cure nr_iowait_cpu() users
  init: Fix comment
  init, sched: Fix race between init and kthreadd

5 files changed, 25 insertions, 13 deletions

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 52ff8aa63f84..1b128702d300 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -143,7 +143,7 @@ static inline int which_bucket(unsigned int duration)
          * This allows us to calculate
          * E(duration)|iowait
          */
-        if (nr_iowait_cpu())
+        if (nr_iowait_cpu(smp_processor_id()))
                 bucket = BUCKETS/2;
 
         if (duration < 10)
@@ -175,7 +175,7 @@ static inline int performance_multiplier(void)
         mult += 2 * get_loadavg();
 
         /* for IO wait tasks (per cpu!) we add 5x each */
-        mult += 10 * nr_iowait_cpu();
+        mult += 10 * nr_iowait_cpu(smp_processor_id());
 
         return mult;
 }
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f118809c953f..747fcaedddb7 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -139,7 +139,7 @@ extern int nr_processes(void);
 extern unsigned long nr_running(void);
 extern unsigned long nr_uninterruptible(void);
 extern unsigned long nr_iowait(void);
-extern unsigned long nr_iowait_cpu(void);
+extern unsigned long nr_iowait_cpu(int cpu);
 extern unsigned long this_cpu_load(void);
 
 
diff --git a/init/main.c b/init/main.c
index ac2e4a5f59ee..a42fdf4aeba9 100644
--- a/init/main.c
+++ b/init/main.c
@@ -424,18 +424,26 @@ static void __init setup_command_line(char *command_line)
  * gcc-3.4 accidentally inlines this function, so use noinline.
  */
 
+static __initdata DECLARE_COMPLETION(kthreadd_done);
+
 static noinline void __init_refok rest_init(void)
         __releases(kernel_lock)
 {
         int pid;
 
         rcu_scheduler_starting();
+        /*
+         * We need to spawn init first so that it obtains pid 1, however
+         * the init task will end up wanting to create kthreads, which, if
+         * we schedule it before we create kthreadd, will OOPS.
+         */
         kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
         numa_default_policy();
         pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
         rcu_read_lock();
         kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
         rcu_read_unlock();
+        complete(&kthreadd_done);
         unlock_kernel();
 
         /*
@@ -857,6 +865,10 @@ static noinline int init_post(void)
 
 static int __init kernel_init(void * unused)
 {
+        /*
+         * Wait until kthreadd is all set-up.
+         */
+        wait_for_completion(&kthreadd_done);
         lock_kernel();
 
         /*
diff --git a/kernel/sched.c b/kernel/sched.c
index cb816e36cc8b..f52a8801b7a2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2873,9 +2873,9 @@ unsigned long nr_iowait(void)
         return sum;
 }
 
-unsigned long nr_iowait_cpu(void)
+unsigned long nr_iowait_cpu(int cpu)
 {
-        struct rq *this = this_rq();
+        struct rq *this = cpu_rq(cpu);
         return atomic_read(&this->nr_iowait);
 }
 
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 783fbadf2202..813993b5fb61 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -154,14 +154,14 @@ static void tick_nohz_update_jiffies(ktime_t now)
  * Updates the per cpu time idle statistics counters
  */
 static void
-update_ts_time_stats(struct tick_sched *ts, ktime_t now, u64 *last_update_time)
+update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now, u64 *last_update_time)
 {
         ktime_t delta;
 
         if (ts->idle_active) {
                 delta = ktime_sub(now, ts->idle_entrytime);
                 ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
-                if (nr_iowait_cpu() > 0)
+                if (nr_iowait_cpu(cpu) > 0)
                         ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta);
                 ts->idle_entrytime = now;
         }
@@ -175,19 +175,19 @@ static void tick_nohz_stop_idle(int cpu, ktime_t now)
 {
         struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
 
-        update_ts_time_stats(ts, now, NULL);
+        update_ts_time_stats(cpu, ts, now, NULL);
         ts->idle_active = 0;
 
         sched_clock_idle_wakeup_event(0);
 }
 
-static ktime_t tick_nohz_start_idle(struct tick_sched *ts)
+static ktime_t tick_nohz_start_idle(int cpu, struct tick_sched *ts)
 {
         ktime_t now;
 
         now = ktime_get();
 
-        update_ts_time_stats(ts, now, NULL);
+        update_ts_time_stats(cpu, ts, now, NULL);
 
         ts->idle_entrytime = now;
         ts->idle_active = 1;
@@ -216,7 +216,7 @@ u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
         if (!tick_nohz_enabled)
                 return -1;
 
-        update_ts_time_stats(ts, ktime_get(), last_update_time);
+        update_ts_time_stats(cpu, ts, ktime_get(), last_update_time);
 
         return ktime_to_us(ts->idle_sleeptime);
 }
@@ -242,7 +242,7 @@ u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time)
         if (!tick_nohz_enabled)
                 return -1;
 
-        update_ts_time_stats(ts, ktime_get(), last_update_time);
+        update_ts_time_stats(cpu, ts, ktime_get(), last_update_time);
 
         return ktime_to_us(ts->iowait_sleeptime);
 }
@@ -284,7 +284,7 @@ void tick_nohz_stop_sched_tick(int inidle)
          */
         ts->inidle = 1;
 
-        now = tick_nohz_start_idle(ts);
+        now = tick_nohz_start_idle(cpu, ts);
 
         /*
          * If this cpu is offline and it is the one which updates