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Commit 874cd339 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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

Pull scheduler fixes from Thomas Gleixner:

 - two patches addressing the problem that the scheduler allows under
   certain conditions user space tasks to be scheduled on CPUs which are
   not yet fully booted which causes a few subtle and hard to debug
   issue

 - add a missing runqueue clock update in the deadline scheduler which
   triggers a warning under certain circumstances

 - fix a silly typo in the scheduler header file

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/headers: Fix typo
  sched/deadline: Fix missing clock update
  sched/core: Require cpu_active() in select_task_rq(), for user tasks
  sched/core: Fix rules for running on online && !active CPUs
parents 26bdace7 595058b6

kernel/sched/core.c

+31 −14
Original line number Diff line number Diff line
@@ -881,6 +881,33 @@ void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) 
}



#ifdef CONFIG_SMP



static inline bool is_per_cpu_kthread(struct task_struct *p)

{

	if (!(p->flags & PF_KTHREAD))

		return false;



	if (p->nr_cpus_allowed != 1)

		return false;



	return true;

}



/*

 * Per-CPU kthreads are allowed to run on !actie && online CPUs, see

 * __set_cpus_allowed_ptr() and select_fallback_rq().

 */

static inline bool is_cpu_allowed(struct task_struct *p, int cpu)

{

	if (!cpumask_test_cpu(cpu, &p->cpus_allowed))

		return false;



	if (is_per_cpu_kthread(p))

		return cpu_online(cpu);



	return cpu_active(cpu);

}



/*

 * This is how migration works:

 *
@@ -938,16 +965,8 @@ struct migration_arg { 
static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,

				 struct task_struct *p, int dest_cpu)

{

	if (p->flags & PF_KTHREAD) {

		if (unlikely(!cpu_online(dest_cpu)))

			return rq;

	} else {

		if (unlikely(!cpu_active(dest_cpu)))

			return rq;

	}



	/* Affinity changed (again). */

	if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed))

	if (!is_cpu_allowed(p, dest_cpu))

		return rq;



	update_rq_clock(rq);
@@ -1476,10 +1495,9 @@ static int select_fallback_rq(int cpu, struct task_struct *p) 
	for (;;) {

		/* Any allowed, online CPU? */

		for_each_cpu(dest_cpu, &p->cpus_allowed) {

			if (!(p->flags & PF_KTHREAD) && !cpu_active(dest_cpu))

				continue;

			if (!cpu_online(dest_cpu))

			if (!is_cpu_allowed(p, dest_cpu))

				continue;



			goto out;

		}
@@ -1542,8 +1560,7 @@ int select_task_rq(struct task_struct *p, int cpu, int sd_flags, int wake_flags) 
	 * [ this allows ->select_task() to simply return task_cpu(p) and

	 *   not worry about this generic constraint ]

	 */

	if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) ||

		     !cpu_online(cpu)))

	if (unlikely(!is_cpu_allowed(p, cpu)))

		cpu = select_fallback_rq(task_cpu(p), p);



	return cpu;

kernel/sched/deadline.c

+3 −3
Original line number Diff line number Diff line
@@ -1259,6 +1259,9 @@ static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer) 


	rq = task_rq_lock(p, &rf);



	sched_clock_tick();

	update_rq_clock(rq);



	if (!dl_task(p) || p->state == TASK_DEAD) {

		struct dl_bw *dl_b = dl_bw_of(task_cpu(p));
@@ -1278,9 +1281,6 @@ static enum hrtimer_restart inactive_task_timer(struct hrtimer *timer) 
	if (dl_se->dl_non_contending == 0)

		goto unlock;



	sched_clock_tick();

	update_rq_clock(rq);



	sub_running_bw(dl_se, &rq->dl);

	dl_se->dl_non_contending = 0;

unlock:

kernel/sched/sched.h

+1 −1
Original line number Diff line number Diff line
@@ -983,7 +983,7 @@ static inline void rq_clock_skip_update(struct rq *rq) 
}



/*

 * See rt task throttoling, which is the only time a skip

 * See rt task throttling, which is the only time a skip

 * request is cancelled.

 */

static inline void rq_clock_cancel_skipupdate(struct rq *rq)