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Commit b2b5ce02 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched, cgroup: Fixup broken cgroup movement 



Dima noticed that we fail to correct the ->vruntime of sleeping tasks
when we move them between cgroups.

Reported-by: default avatarDima Zavin <dima@android.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: default avatarMike Galbraith <efault@gmx.de>
LKML-Reference: <1287150604.29097.1513.camel@twins>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent b7dadc38

include/linux/sched.h

+1 −1
Original line number Diff line number Diff line
@@ -1073,7 +1073,7 @@ struct sched_class { 
					 struct task_struct *task);



#ifdef CONFIG_FAIR_GROUP_SCHED

	void (*moved_group) (struct task_struct *p, int on_rq);

	void (*task_move_group) (struct task_struct *p, int on_rq);

#endif

};

kernel/sched.c

+4 −4
Original line number Diff line number Diff line
@@ -8498,12 +8498,12 @@ void sched_move_task(struct task_struct *tsk) 
	if (unlikely(running))

		tsk->sched_class->put_prev_task(rq, tsk);



	set_task_rq(tsk, task_cpu(tsk));



#ifdef CONFIG_FAIR_GROUP_SCHED

	if (tsk->sched_class->moved_group)

		tsk->sched_class->moved_group(tsk, on_rq);

	if (tsk->sched_class->task_move_group)

		tsk->sched_class->task_move_group(tsk, on_rq);

	else

#endif

		set_task_rq(tsk, task_cpu(tsk));



	if (unlikely(running))

		tsk->sched_class->set_curr_task(rq);

kernel/sched_fair.c

+19 −6
Original line number Diff line number Diff line
@@ -3866,13 +3866,26 @@ static void set_curr_task_fair(struct rq *rq) 
}



#ifdef CONFIG_FAIR_GROUP_SCHED

static void moved_group_fair(struct task_struct *p, int on_rq)

static void task_move_group_fair(struct task_struct *p, int on_rq)

{

	struct cfs_rq *cfs_rq = task_cfs_rq(p);



	update_curr(cfs_rq);

	/*

	 * If the task was not on the rq at the time of this cgroup movement

	 * it must have been asleep, sleeping tasks keep their ->vruntime

	 * absolute on their old rq until wakeup (needed for the fair sleeper

	 * bonus in place_entity()).

	 *

	 * If it was on the rq, we've just 'preempted' it, which does convert

	 * ->vruntime to a relative base.

	 *

	 * Make sure both cases convert their relative position when migrating

	 * to another cgroup's rq. This does somewhat interfere with the

	 * fair sleeper stuff for the first placement, but who cares.

	 */

	if (!on_rq)

		p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime;

	set_task_rq(p, task_cpu(p));

	if (!on_rq)

		place_entity(cfs_rq, &p->se, 1);

		p->se.vruntime += cfs_rq_of(&p->se)->min_vruntime;

}

#endif
@@ -3924,7 +3937,7 @@ static const struct sched_class fair_sched_class = { 
	.get_rr_interval	= get_rr_interval_fair,



#ifdef CONFIG_FAIR_GROUP_SCHED

	.moved_group		= moved_group_fair,

	.task_move_group	= task_move_group_fair,

#endif

};