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Thu, 05 Aug 2021 02:40:40 -0700 (PDT) Received: from localhost.localdomain ([151.29.52.108]) by smtp.gmail.com with ESMTPSA id nd14sm1473976ejc.113.2021.08.05.02.40.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Aug 2021 02:40:40 -0700 (PDT) Date: Thu, 5 Aug 2021 11:40:38 +0200 From: Juri Lelli To: Dietmar Eggemann Cc: Ingo Molnar , Peter Zijlstra , Steven Rostedt , Vincent Guittot , Daniel Bristot de Oliveira , Bruno Goncalves , linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched/deadline: Fix missing clock update in migrate_task_rq_dl() Message-ID: References: <20210804135925.3734605-1-dietmar.eggemann@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210804135925.3734605-1-dietmar.eggemann@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 04/08/21 15:59, Dietmar Eggemann wrote: > A missing clock update is causing the following warning: > > rq->clock_update_flags < RQCF_ACT_SKIP > WARNING: CPU: 112 PID: 2041 at kernel/sched/sched.h:1453 > sub_running_bw.isra.0+0x190/0x1a0 > ... > CPU: 112 PID: 2041 Comm: sugov:112 Tainted: G W 5.14.0-rc1 #1 > Hardware name: WIWYNN Mt.Jade Server System > B81.030Z1.0007/Mt.Jade Motherboard, BIOS 1.6.20210526 (SCP: > 1.06.20210526) 2021/05/26 > ... > Call trace: > sub_running_bw.isra.0+0x190/0x1a0 > migrate_task_rq_dl+0xf8/0x1e0 > set_task_cpu+0xa8/0x1f0 > try_to_wake_up+0x150/0x3d4 > wake_up_q+0x64/0xc0 > __up_write+0xd0/0x1c0 > up_write+0x4c/0x2b0 > cppc_set_perf+0x120/0x2d0 > cppc_cpufreq_set_target+0xe0/0x1a4 [cppc_cpufreq] > __cpufreq_driver_target+0x74/0x140 > sugov_work+0x64/0x80 > kthread_worker_fn+0xe0/0x230 > kthread+0x138/0x140 > ret_from_fork+0x10/0x18 > > The task causing this is the `cppc_fie` DL task introduced by > commit 1eb5dde674f5 ("cpufreq: CPPC: Add support for frequency > invariance"). > > With CONFIG_ACPI_CPPC_CPUFREQ_FIE=y and schedutil cpufreq governor on > slow-switching system (like on this Ampere Altra WIWYNN Mt. Jade Arm > Server): > > DL task `curr=sugov:112` lets `p=cppc_fie` migrate and since the latter > is in `non_contending` state, migrate_task_rq_dl() calls > > sub_running_bw()->__sub_running_bw()->cpufreq_update_util()-> > rq_clock()->assert_clock_updated() > > on p. > > Fix this by updating the clock for a non_contending task in > migrate_task_rq_dl() before calling sub_running_bw(). > > Reported-by: Bruno Goncalves > Signed-off-by: Dietmar Eggemann > --- > kernel/sched/deadline.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index aaacd6cfd42f..4920f498492f 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -1733,6 +1733,7 @@ static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused > */ > raw_spin_rq_lock(rq); > if (p->dl.dl_non_contending) { > + update_rq_clock(rq); > sub_running_bw(&p->dl, &rq->dl); > p->dl.dl_non_contending = 0; > /* Acked-by: Juri Lelli Thanks! Juri