From: Qais Yousef qais.yousef@arm.com
[ Upstream commit d81ae8aac85ca2e307d273f6dc7863a721bf054e ]
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@arm.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Valentin Schneider valentin.schneider@arm.com Tested-by: Lukasz Luba lukasz.luba@arm.com Link: https://lkml.kernel.org/r/20200630112123.12076-2-qais.yousef@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 2142c67676826..c3cbdc436e2e4 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1237,6 +1237,20 @@ 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 = {}; @@ -1245,11 +1259,8 @@ 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],