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.you...@arm.com> Cc: Juri Lelli <juri.le...@redhat.com> Cc: Vincent Guittot <vincent.guit...@linaro.org> Cc: Dietmar Eggemann <dietmar.eggem...@arm.com> Cc: Steven Rostedt <rost...@goodmis.org> Cc: Ben Segall <bseg...@google.com> Cc: Mel Gorman <mgor...@suse.de> CC: Patrick Bellasi <patrick.bell...@matbug.net> Cc: Chris Redpath <chrid.redp...@arm.com> Cc: Lukasz Luba <lukasz.l...@arm.com> Cc: linux-kernel@vger.kernel.org --- kernel/sched/core.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a43c84c27c6f..e19d2b915406 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1248,6 +1248,20 @@ 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) { + memset(uc_rq[clamp_id].bucket, + 0, + sizeof(struct uclamp_bucket)*UCLAMP_BUCKETS); + + uc_rq[clamp_id].value = uclamp_none(clamp_id); + } +} + static void __init init_uclamp(void) { struct uclamp_se uc_max = {}; @@ -1257,8 +1271,7 @@ 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); + init_uclamp_rq(cpu_rq(cpu)); cpu_rq(cpu)->uclamp_flags = 0; } -- 2.17.1