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sched/fair: Use cfs_rq->h_curr in throttle_cfs_rq()

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After commit 85570f10a4 ("sched/eevdf: Move to a single runqueue"),
cfs_rq->curr is only maintained on the root cfs_rq (set/cleared from
set_next_task_fair()/put_prev_task_fair()), while cfs_rq->h_curr is
the per-level current entity, set by set_next_entity() at every level
of the hierarchy. For an intermediate cfs_rq (a cgroup), cfs_rq->curr
is always NULL, but cfs_rq->h_curr is the group entity at that level.

throttle_cfs_rq() reads cfs_rq->curr to decide whether there is a
running entity at the throttled level, in which case it should request
a full sched_cfs_bandwidth_slice() of runtime and arm the deferred
throttle task_work via task_throttle_setup_work(). For intermediate
cfs_rqs the check is always false, so bandwidth-controlled cgroups
always get just 1ns of runtime and never arm the deferred throttle
work; the running task then escapes throttling until the next pick
arms the work instead, even though there is an on-rq entity at this
level.

Switch the read to cfs_rq->h_curr so intermediate bandwidth-controlled
cgroups behave consistently with the root cfs_rq, matching the
existing usage of cfs_rq->h_curr in update_curr() and
check_enqueue_throttle().

Fixes: 85570f10a4 ("sched/eevdf: Move to a single runqueue")
Signed-off-by: Wanwu Li <liwanwu@kylinos.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Aaron Lu <ziqianlu@bytedance.com>
Tested-by: Aaron Lu <ziqianlu@bytedance.com>
Link: https://patch.msgid.link/20260831101141.391382-2-liwanwu@kylinos.cn
This commit is contained in:
Wanwu Li 2026-08-31 18:11:40 +08:00 committed by Peter Zijlstra
parent c6dcd97c8b
commit f8610c57f4
1 changed files with 2 additions and 2 deletions
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4
kernel/sched/fair.c
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@ -6978,14 +6978,14 @@ static int tg_throttle_down(struct task_group *tg, void *data)
static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
{
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
struct sched_entity *curr = cfs_rq->curr;
struct sched_entity *curr = cfs_rq->h_curr;
struct rq *rq = rq_of(cfs_rq);
scoped_guard(raw_spinlock, &cfs_b->lock) {
u64 target_runtime = 1;
/*
* If cfs_rq->curr is still runnable, we are here from an
* If cfs_rq->h_curr is still runnable, we are here from an
* update_curr(). Request sysctl_sched_cfs_bandwidth_slice
* worth of bandwidth to continue running.
*