[GIT PULL] scheduler fixes

Ingo Molnar
2021-07-11T13:33:01Z

Linus,

Please pull the latest sched/urgent git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-2021-07-11

# HEAD: 3e1493f46390618ea78607cb30c58fc19e2a5035 sched/uclamp: Ignore max aggregation if rq is idle

Three fixes:

- Fix load tracking bug/inconsistency
- Fix a sporadic CFS bandwidth constraints enforcement bug
- Fix a uclamp utilization tracking bug for newly woken tasks

Thanks,

Ingo

------------------>
Odin Ugedal (1):
sched/fair: Fix CFS bandwidth hrtimer expiry type

Vincent Guittot (1):
sched/fair: Sync load_sum with load_avg after dequeue

Xuewen Yan (1):
sched/uclamp: Ignore max aggregation if rq is idle

kernel/sched/fair.c | 7 ++++---
kernel/sched/sched.h | 21 ++++++++++++++-------
2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 45edf61eed73..1b15a19910a3 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3037,8 +3037,9 @@ enqueue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
static inline void
dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
+ u32 divider = get_pelt_divider(&se->avg);
sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
- sub_positive(&cfs_rq->avg.load_sum, se_weight(se) * se->avg.load_sum);
+ cfs_rq->avg.load_sum = cfs_rq->avg.load_avg * divider;
}
#else
static inline void
@@ -5053,7 +5054,7 @@ static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
{
struct hrtimer *refresh_timer = &cfs_b->period_timer;
- u64 remaining;
+ s64 remaining;

/* if the call-back is running a quota refresh is already occurring */
if (hrtimer_callback_running(refresh_timer))
@@ -5061,7 +5062,7 @@ static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)

/* is a quota refresh about to occur? */
remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
- if (remaining < min_expire)
+ if (remaining < (s64)min_expire)
return 1;

return 0;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c80d42e9589b..14a41a243f7b 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2818,20 +2818,27 @@ static __always_inline
unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
struct task_struct *p)
{
- unsigned long min_util;
- unsigned long max_util;
+ unsigned long min_util = 0;
+ unsigned long max_util = 0;

if (!static_branch_likely(&sched_uclamp_used))
return util;

- min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value);
- max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value);
-
if (p) {
- min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN));
- max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
+ min_util = uclamp_eff_value(p, UCLAMP_MIN);
+ max_util = uclamp_eff_value(p, UCLAMP_MAX);
+
+ /*
+ * Ignore last runnable task's max clamp, as this task will
+ * reset it. Similarly, no need to read the rq's min clamp.
+ */
+ if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
+ goto out;
}

+ min_util = max_t(unsigned long, min_util, READ_ONCE(rq->uclamp[UCLAMP_MIN].value));
+ max_util = max_t(unsigned long, max_util, READ_ONCE(rq->uclamp[UCLAMP_MAX].value));
+out:
/*
* Since CPU's {min,max}_util clamps are MAX aggregated considering
* RUNNABLE tasks with _different_ clamps, we can end up with an