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

Pull scheduler fixes from Ingo Molnar:
 "Misc fixes"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix comment for sched_info_depart
  sched/Documentation: Update sched-design-CFS.txt documentation
  sched/debug: Take PID namespace into account
  sched/fair: Fix small race where child->se.parent,cfs_rq might point to invalid ones

3 files changed, 15 insertions, 10 deletions

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index e076bddd4c66..196559994f7c 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -124,7 +124,7 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
                 SEQ_printf(m, " ");
 
         SEQ_printf(m, "%15s %5d %9Ld.%06ld %9Ld %5d ",
-                p->comm, p->pid,
+                p->comm, task_pid_nr(p),
                 SPLIT_NS(p->se.vruntime),
                 (long long)(p->nvcsw + p->nivcsw),
                 p->prio);
@@ -289,7 +289,7 @@ do {									\
         P(nr_load_updates);
         P(nr_uninterruptible);
         PN(next_balance);
-        P(curr->pid);
+        SEQ_printf(m, "  .%-30s: %ld\n", "curr->pid", (long)(task_pid_nr(rq->curr)));
         PN(clock);
         P(cpu_load[0]);
         P(cpu_load[1]);
@@ -492,7 +492,7 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
 {
         unsigned long nr_switches;
 
-        SEQ_printf(m, "%s (%d, #threads: %d)\n", p->comm, p->pid,
+        SEQ_printf(m, "%s (%d, #threads: %d)\n", p->comm, task_pid_nr(p),
                                                 get_nr_threads(p));
         SEQ_printf(m,
                 "---------------------------------------------------------"
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9b3fe1cd8f40..11cd13667359 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5928,11 +5928,15 @@ static void task_fork_fair(struct task_struct *p)
         cfs_rq = task_cfs_rq(current);
         curr = cfs_rq->curr;
 
-        if (unlikely(task_cpu(p) != this_cpu)) {
-                rcu_read_lock();
-                __set_task_cpu(p, this_cpu);
-                rcu_read_unlock();
-        }
+        /*
+         * Not only the cpu but also the task_group of the parent might have
+         * been changed after parent->se.parent,cfs_rq were copied to
+         * child->se.parent,cfs_rq. So call __set_task_cpu() to make those
+         * of child point to valid ones.
+         */
+        rcu_read_lock();
+        __set_task_cpu(p, this_cpu);
+        rcu_read_unlock();
 
         update_curr(cfs_rq);
 
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index 5aef494fc8b4..c7edee71bce8 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -104,8 +104,9 @@ 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.
+ * Called when a process ceases being the active-running process involuntarily
+ * due, typically, to expiring its time slice (this may also be called when
+ * switching to the idle task).  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.