From: Frederic Weisbecker <frederic@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Nicholas Piggin <npiggin@gmail.com>,
Leonardo Bras <leobras@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Tejun Heo <tj@kernel.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
linux-kernel@vger.kernel.org, Junyao Zhao <junzhao@redhat.com>,
Chris von Recklinghausen <crecklin@redhat.com>
Subject: Re: [PATCH] sched/isolation: fix boot crash when the boot CPU is nohz_full
Date: Mon, 15 Apr 2024 23:37:49 +0200 [thread overview]
Message-ID: <Zh2eLUFm3LQvYVtF@pavilion.home> (raw)
In-Reply-To: <20240411143905.GA19288@redhat.com>
Le Thu, Apr 11, 2024 at 04:39:05PM +0200, Oleg Nesterov a écrit :
> Documentation/timers/no_hz.rst states that the "nohz_full=" mask must not
> include the boot CPU, this is no longer true after the commit 08ae95f4fd3b
> ("nohz_full: Allow the boot CPU to be nohz_full").
>
> However after another commit aae17ebb53cd ("workqueue: Avoid using isolated
> cpus' timers on queue_delayed_work") the kernel will crash at boot time in
> this case; housekeeping_any_cpu() returns an invalid cpu nr until smp_init()
> paths bring the 1st housekeeping CPU up.
>
> Change housekeeping_any_cpu() to check the result of cpumask_any_and() and
> return smp_processor_id() in this case. Yes, this is just the simple and
> backportable workaround which fixes the symptom, but smp_processor_id() at
> boot time should be safe at least for type == HK_TYPE_TIMER, this more or
> less matches the tick_do_timer_boot_cpu logic.
>
> We should not worry about cpu_down(); tick_nohz_cpu_down() will not allow
> to offline tick_do_timer_cpu (the 1st online housekeeping CPU).
>
> Fixes: aae17ebb53cd ("workqueue: Avoid using isolated cpus' timers on queue_delayed_work")
> Reported-by: Chris von Recklinghausen <crecklin@redhat.com>
> Closes: https://lore.kernel.org/all/20240402105847.GA24832@redhat.com/
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
next prev parent reply other threads:[~2024-04-15 21:37 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-30 1:00 [PATCH v2 1/1] wq: Avoid using isolated cpus' timers on queue_delayed_work Leonardo Bras
2024-01-30 1:22 ` Tejun Heo
2024-01-30 2:58 ` Leonardo Bras
2024-04-02 10:58 ` Oleg Nesterov
2024-04-03 19:12 ` Tejun Heo
2024-04-03 20:38 ` Oleg Nesterov
2024-04-05 14:04 ` Oleg Nesterov
2024-04-05 15:38 ` Tejun Heo
2024-04-05 22:03 ` Frederic Weisbecker
2024-04-05 21:52 ` Nohz_full on boot CPU is broken (was: Re: [PATCH v2 1/1] wq: Avoid using isolated cpus' timers on queue_delayed_work) Frederic Weisbecker
2024-04-07 13:09 ` Oleg Nesterov
2024-04-07 13:52 ` Oleg Nesterov
2024-04-09 12:05 ` Frederic Weisbecker
2024-04-09 12:04 ` Frederic Weisbecker
2024-04-09 13:07 ` Oleg Nesterov
2024-04-09 13:59 ` Frederic Weisbecker
2024-04-10 4:26 ` Nicholas Piggin
2024-04-10 13:55 ` Oleg Nesterov
2024-04-11 13:41 ` Oleg Nesterov
2024-04-11 14:39 ` [PATCH] sched/isolation: fix boot crash when the boot CPU is nohz_full Oleg Nesterov
2024-04-11 16:59 ` Oleg Nesterov
2024-04-13 14:17 ` [PATCH] sched/isolation: fix boot crash when maxcpus < first-housekeeping-cpu Oleg Nesterov
2024-04-18 14:54 ` Phil Auld
2024-04-18 15:40 ` Frederic Weisbecker
2024-04-24 20:05 ` [tip: sched/urgent] sched/isolation: Fix boot crash when maxcpus < first housekeeping CPU tip-bot2 for Oleg Nesterov
2024-04-28 8:13 ` Ingo Molnar
2024-04-28 13:16 ` Oleg Nesterov
2024-04-28 8:24 ` tip-bot2 for Oleg Nesterov
2024-04-15 21:37 ` Frederic Weisbecker [this message]
2024-04-18 14:50 ` [PATCH] sched/isolation: fix boot crash when the boot CPU is nohz_full Phil Auld
2024-04-22 18:50 ` Oleg Nesterov
2024-04-24 14:42 ` Phil Auld
2024-04-24 20:05 ` [tip: sched/urgent] sched/isolation: {revent " tip-bot2 for Oleg Nesterov
2024-04-24 20:41 ` Phil Auld
2024-04-28 8:14 ` Ingo Molnar
2024-04-29 11:50 ` Phil Auld
2024-04-28 8:24 ` [tip: sched/urgent] sched/isolation: Prevent " tip-bot2 for Oleg Nesterov
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