The following commit has been merged into the sched/core branch of tip: Commit-ID: d81ae8aac85ca2e307d273f6dc7863a721bf054e Gitweb: https://git.kernel.org/tip/d81ae8aac85ca2e307d273f6dc7863a721bf054e Author: Qais Yousef <qais.yousef@xxxxxxx> AuthorDate: Tue, 30 Jun 2020 12:21:22 +01:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Wed, 08 Jul 2020 11:39:01 +02:00 sched/uclamp: Fix initialization of struct uclamp_rq struct uclamp_rq was zeroed out entirely in assumption that in the first call to uclamp_rq_inc() they'd be initialized correctly in accordance to default settings. But when next patch introduces a static key to skip uclamp_rq_{inc,dec}() until userspace opts in to use uclamp, schedutil will fail to perform any frequency changes because the rq->uclamp[UCLAMP_MAX].value is zeroed at init and stays as such. Which means all rqs are capped to 0 by default. Fix it by making sure we do proper initialization at init without relying on uclamp_rq_inc() doing it later. Fixes: 69842cba9ace ("sched/uclamp: Add CPU's clamp buckets refcounting") Signed-off-by: Qais Yousef <qais.yousef@xxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Reviewed-by: Valentin Schneider <valentin.schneider@xxxxxxx> Tested-by: Lukasz Luba <lukasz.luba@xxxxxxx> Link: https://lkml.kernel.org/r/20200630112123.12076-2-qais.yousef@xxxxxxx --- kernel/sched/core.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 15c980a..9605db7 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1239,6 +1239,20 @@ static void uclamp_fork(struct task_struct *p) } } +static void __init init_uclamp_rq(struct rq *rq) +{ + enum uclamp_id clamp_id; + struct uclamp_rq *uc_rq = rq->uclamp; + + for_each_clamp_id(clamp_id) { + uc_rq[clamp_id] = (struct uclamp_rq) { + .value = uclamp_none(clamp_id) + }; + } + + rq->uclamp_flags = 0; +} + static void __init init_uclamp(void) { struct uclamp_se uc_max = {}; @@ -1247,11 +1261,8 @@ static void __init init_uclamp(void) mutex_init(&uclamp_mutex); - for_each_possible_cpu(cpu) { - memset(&cpu_rq(cpu)->uclamp, 0, - sizeof(struct uclamp_rq)*UCLAMP_CNT); - cpu_rq(cpu)->uclamp_flags = 0; - } + for_each_possible_cpu(cpu) + init_uclamp_rq(cpu_rq(cpu)); for_each_clamp_id(clamp_id) { uclamp_se_set(&init_task.uclamp_req[clamp_id],
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