From: "Cheng-Jui Wang (王正睿)" <Cheng-Jui.Wang@mediatek.com>
To: "frederic@kernel.org" <frederic@kernel.org>,
"qiang.zhang1211@gmail.com" <qiang.zhang1211@gmail.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"peterz@infradead.org" <peterz@infradead.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"neeraj.upadhyay@amd.com" <neeraj.upadhyay@amd.com>,
"paulmck@kernel.org" <paulmck@kernel.org>,
"Bobule Chang (張弘義)" <bobule.chang@mediatek.com>,
"boqun.feng@gmail.com" <boqun.feng@gmail.com>,
"urezki@gmail.com" <urezki@gmail.com>,
"joel@joelfernandes.org" <joel@joelfernandes.org>,
"rcu@vger.kernel.org" <rcu@vger.kernel.org>
Subject: Re: [PATCH 2/3] rcu: Defer RCU kthreads wakeup when CPU is dying
Date: Mon, 12 Aug 2024 09:10:56 +0000 [thread overview]
Message-ID: <65b6b97a6f61f80c5f1ea1f245eea392a0de5523.camel@mediatek.com> (raw)
In-Reply-To: <ZYMElDsPLTJDdco3@localhost.localdomain>
On Wed, 2023-12-20 at 16:13 +0100, Frederic Weisbecker wrote:
> Le Wed, Dec 20, 2023 at 04:24:35PM +0800, Z qiang a écrit :
> > >
> >
> > In the rcutree_report_cpu_dead(), the rcuog kthreads may also be
> > wakeup in
> > do_nocb_deferred_wakeup(), if the rcuog kthreads is rt-fifo and
> > wakeup happen,
> > the rt_period_active is set 1 and enqueue hrtimer to offline CPU in
> > do_start_rt_bandwidth(),
> > after that, we invoke swake_up_one_online() send ipi to online CPU,
> > due to the
> > rt_period_active is 1, the rt-bandwith hrtimer will not enqueue to
> > online CPU.
> > any thoughts?
>
> Duh, you're right, that one too. How many more? This hrtimer
> situation is scary...
>
> Thanks.
I encountered the issue pointed out by Z Qiang on kernel-6.6, which
cause RT tasks on the CPU to never be scheduled, leading to a system
reboot. It triggered the WARN_ON_ONCE(!base->cpu_base->online)
introduced in [PATCH 1/3]. Below is the call trace:
Call trace:
enqueue_hrtimer+0x7c/0xf8
hrtimer_start_range_ns+0x2b8/0x300
enqueue_task_rt+0x298/0x3f0
enqueue_task+0x94/0x188
ttwu_do_activate+0xb4/0x27c
try_to_wake_up+0x2d8/0x79c
wake_up_process+0x18/0x28
__wake_nocb_gp+0x80/0x1a0
do_nocb_deferred_wakeup_common+0x3c/0xcc
rcu_report_dead+0x68/0x1ac
cpuhp_report_idle_dead+0x48/0x9c
do_idle+0x288/0x294
cpu_startup_entry+0x34/0x3c
secondary_start_kernel+0x138/0x158
next prev parent reply other threads:[~2024-08-12 9:11 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-18 23:19 [PATCH 0/3] timers & RCU: Fix TREE03 stalls Frederic Weisbecker
2023-12-18 23:19 ` [PATCH 1/3] hrtimer: Report offline hrtimer enqueue Frederic Weisbecker
2023-12-18 23:19 ` [PATCH 2/3] rcu: Defer RCU kthreads wakeup when CPU is dying Frederic Weisbecker
2023-12-19 3:38 ` Joel Fernandes
2023-12-19 11:56 ` Frederic Weisbecker
2023-12-20 3:01 ` Joel Fernandes
2023-12-20 15:50 ` Frederic Weisbecker
2023-12-21 0:57 ` Paul E. McKenney
2023-12-19 4:42 ` Hillf Danton
2023-12-19 23:42 ` Frederic Weisbecker
2023-12-19 15:29 ` Paul E. McKenney
2023-12-19 15:47 ` Frederic Weisbecker
2023-12-20 8:24 ` Z qiang
2023-12-20 15:13 ` Frederic Weisbecker
2024-08-12 9:10 ` Cheng-Jui Wang (王正睿) [this message]
2024-08-12 11:13 ` Frederic Weisbecker
2024-08-12 11:53 ` Cheng-Jui Wang (王正睿)
2023-12-18 23:19 ` [PATCH 3/3] rcu/exp: Remove full barrier upon main thread wakeup Frederic Weisbecker
2023-12-19 1:40 ` [PATCH 0/3] timers & RCU: Fix TREE03 stalls Paul E. McKenney
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