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

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Ingo writes:
  "scheduler fixes:

   Two fixes: a CFS-throttling bug fix, and an interactivity fix."

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix the min_vruntime update logic in dequeue_entity()
  sched/fair: Fix throttle_list starvation with low CFS quota
This commit is contained in:
Greg Kroah-Hartman 2018-10-20 15:03:45 +02:00
commit 14dbc56aa2
2 changed files with 22 additions and 4 deletions
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24
kernel/sched/fair.c
View File

@ -4001,7 +4001,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* put back on, and if we advance min_vruntime, we'll be placed back
* further than we started -- ie. we'll be penalized.
*/
if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE)
if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) != DEQUEUE_SAVE)
update_min_vruntime(cfs_rq);
}
@ -4476,9 +4476,13 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
/*
* Add to the _head_ of the list, so that an already-started
* distribute_cfs_runtime will not see us
* distribute_cfs_runtime will not see us. If disribute_cfs_runtime is
* not running add to the tail so that later runqueues don't get starved.
*/
list_add_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
if (cfs_b->distribute_running)
list_add_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
else
list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
/*
* If we're the first throttled task, make sure the bandwidth
@ -4622,14 +4626,16 @@ static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
* in us over-using our runtime if it is all used during this loop, but
* only by limited amounts in that extreme case.
*/
while (throttled && cfs_b->runtime > 0) {
while (throttled && cfs_b->runtime > 0 && !cfs_b->distribute_running) {
runtime = cfs_b->runtime;
cfs_b->distribute_running = 1;
raw_spin_unlock(&cfs_b->lock);
/* we can't nest cfs_b->lock while distributing bandwidth */
runtime = distribute_cfs_runtime(cfs_b, runtime,
runtime_expires);
raw_spin_lock(&cfs_b->lock);
cfs_b->distribute_running = 0;
throttled = !list_empty(&cfs_b->throttled_cfs_rq);
cfs_b->runtime -= min(runtime, cfs_b->runtime);
@ -4740,6 +4746,11 @@ static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
/* confirm we're still not at a refresh boundary */
raw_spin_lock(&cfs_b->lock);
if (cfs_b->distribute_running) {
raw_spin_unlock(&cfs_b->lock);
return;
}
if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) {
raw_spin_unlock(&cfs_b->lock);
return;
@ -4749,6 +4760,9 @@ static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
runtime = cfs_b->runtime;
expires = cfs_b->runtime_expires;
if (runtime)
cfs_b->distribute_running = 1;
raw_spin_unlock(&cfs_b->lock);
if (!runtime)
@ -4759,6 +4773,7 @@ static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
raw_spin_lock(&cfs_b->lock);
if (expires == cfs_b->runtime_expires)
cfs_b->runtime -= min(runtime, cfs_b->runtime);
cfs_b->distribute_running = 0;
raw_spin_unlock(&cfs_b->lock);
}
@ -4867,6 +4882,7 @@ void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
cfs_b->period_timer.function = sched_cfs_period_timer;
hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
cfs_b->slack_timer.function = sched_cfs_slack_timer;
cfs_b->distribute_running = 0;
}
static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)

2
kernel/sched/sched.h
View File

@ -346,6 +346,8 @@ struct cfs_bandwidth {
int nr_periods;
int nr_throttled;
u64 throttled_time;
bool distribute_running;
#endif
};