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Commit 2b4cf585 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 Ingo Molnar:
 "A deadline scheduler warning/race fix, and a cfs_period_us quota
  calculation workaround where the real fix looks too involved to merge
  immediately"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/deadline: Correctly handle active 0-lag timers
  sched/fair: Limit sched_cfs_period_timer() loop to avoid hard lockup
parents de3af9a9 1b02cd6a

kernel/sched/deadline.c

+1 −2
Original line number Diff line number Diff line
@@ -252,7 +252,6 @@ static void task_non_contending(struct task_struct *p) 
	if (dl_entity_is_special(dl_se))

		return;



	WARN_ON(hrtimer_active(&dl_se->inactive_timer));

	WARN_ON(dl_se->dl_non_contending);



	zerolag_time = dl_se->deadline -
@@ -269,7 +268,7 @@ static void task_non_contending(struct task_struct *p) 
	 * If the "0-lag time" already passed, decrease the active

	 * utilization now, instead of starting a timer

	 */

	if (zerolag_time < 0) {

	if ((zerolag_time < 0) || hrtimer_active(&dl_se->inactive_timer)) {

		if (dl_task(p))

			sub_running_bw(dl_se, dl_rq);

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

kernel/sched/fair.c

+25 −0
Original line number Diff line number Diff line
@@ -4885,6 +4885,8 @@ static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer) 
	return HRTIMER_NORESTART;

}



extern const u64 max_cfs_quota_period;



static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)

{

	struct cfs_bandwidth *cfs_b =
@@ -4892,6 +4894,7 @@ static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) 
	unsigned long flags;

	int overrun;

	int idle = 0;

	int count = 0;



	raw_spin_lock_irqsave(&cfs_b->lock, flags);

	for (;;) {
@@ -4899,6 +4902,28 @@ static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) 
		if (!overrun)

			break;



		if (++count > 3) {

			u64 new, old = ktime_to_ns(cfs_b->period);



			new = (old * 147) / 128; /* ~115% */

			new = min(new, max_cfs_quota_period);



			cfs_b->period = ns_to_ktime(new);



			/* since max is 1s, this is limited to 1e9^2, which fits in u64 */

			cfs_b->quota *= new;

			cfs_b->quota = div64_u64(cfs_b->quota, old);



			pr_warn_ratelimited(

	"cfs_period_timer[cpu%d]: period too short, scaling up (new cfs_period_us %lld, cfs_quota_us = %lld)\n",

				smp_processor_id(),

				div_u64(new, NSEC_PER_USEC),

				div_u64(cfs_b->quota, NSEC_PER_USEC));



			/* reset count so we don't come right back in here */

			count = 0;

		}



		idle = do_sched_cfs_period_timer(cfs_b, overrun, flags);

	}

	if (idle)