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

Documentation/scheduler/sched-design-CFS.txt

@@ -66,9 +66,7 @@ rq->cfs.load value, which is the sum of the weights of the tasks queued on the
 runqueue.
 
 CFS maintains a time-ordered rbtree, where all runnable tasks are sorted by the
-p->se.vruntime key (there is a subtraction using rq->cfs.min_vruntime to
+p->se.vruntime key. CFS picks the "leftmost" task from this tree and sticks to it.
-account for possible wraparounds).  CFS picks the "leftmost" task from this
-tree and sticks to it.
 As the system progresses forwards, the executed tasks are put into the tree
 more and more to the right --- slowly but surely giving a chance for every task
 to become the "leftmost task" and thus get on the CPU within a deterministic

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,
 		"---------------------------------------------------------"

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)) {
+	/*
+	 * 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);
 

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
+ * Called when a process ceases being the active-running process involuntarily
- * voluntarily or involuntarily.  Now we can calculate how long we ran.
+ * 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.