[STABLE] kernel oops which can be fixed by peterz's patches

[Byungchul Park <byungchul.park@lge.com>]

Upstream commits to be applied
==============================

e3fca9e: sched: Replace post_schedule with a balance callback list
4c9a4bc: sched: Allow balance callbacks for check_class_changed()
8046d68: sched,rt: Remove return value from pull_rt_task()
fd7a4be: sched, rt: Convert switched_{from, to}_rt() / prio_changed_rt() to balance callbacks
0ea60c2: sched,dl: Remove return value from pull_dl_task()
9916e21: sched, dl: Convert switched_{from, to}_dl() / prio_changed_dl() to balance callbacks

The reason why these should be applied
======================================

Our products developed using 3.16 kernel, faced a kernel oops which can
be fixed with above upstreamed patches. The oops is caused by "Unable
to handle kernel NULL pointer dereference at virtual address 000000xx"
in the call path,

__sched_setscheduler()
	check_class_changed()
		switched_to_fair()
			check_preempt_curr()
				check_preempt_wakeup()
					find_matching_se()
						is_same_group()

by "if (se->cfs_rq == pse->cfs_rq) // se, pse == NULL" condition.

How to apply it
===============

For stable 4.2.8+:
	N/A (already applied)

For longterm 4.1.15:
	Cherry-picking the upsteam commits works with a trivial conflict.

For longterm 3.18.25:
	Refer to the backported patches in this thread.

For longterm 3.14.58:
	Refer to the backported patches in this thread. And applying
	additional "6c3b4d4: sched: Clean up idle task SMP logic" commit
	makes backporting the upstream commits much simpler. So my
	backporting patches include the patch.

For longterm 2.6.32.69 ~ 3.12.51: Need to be backported. (I didn't)