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From: Jonas Jelonek <jelonek.jonas@gmail.com>
To: Huacai Chen <chenhuacai@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	linux-mips@vger.kernel.org,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Clark Williams <clrkwllms@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@kernel.org>,
	Jiayuan Chen <jiayuan.chen@linux.dev>,
	linux-rt-devel@lists.linux.dev, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH v2] MIPS: smp: report dying CPU to RCU in stop_this_cpu()
Date: Mon, 15 Jun 2026 09:40:45 +0200	[thread overview]
Message-ID: <9cd444b3-aeb0-46bb-a8a3-1526aa8f191a@gmail.com> (raw)
In-Reply-To: <CAAhV-H5psOJQey+frswdc5Q76UnhCkrHJ_jtqvxHsfmi-dskyw@mail.gmail.com>

On 15.06.26 09:30, Huacai Chen wrote:
>> [...]
>>
>>> However, synchronize_rcu() only gets called in the
>>> IS_ENABLED(CONFIG_PREEMPT_RT) case, so I think your configuration
>>> needs PREEMPT_RT, right?
>>>
>>> You said this is the default behavior, but PREEMPT_RT is not enabled by default.
>> The condition where this is added has two parts, see [1]. While PREEMPT_RT
>> isn't active for MIPS, arch_irq_work_has_interrupt gives false for MIPS (since
>> there is no implementation and it falls back to the generic one). This then
>> also calls synchronize_rcu.
> Sorry, this is my mistake, then what's your preemption model? There
> are too many config files for MIPS now.

I'm using PREEMPT_NONE, apparently default for all targets in OpenWrt.

> Huacai
>
>>> Huacai
>>>
>> Best,
>> Jonas
>>
>> [1] https://elixir.bootlin.com/linux/v7.1-rc7/source/kernel/irq_work.c#L291-L302

Best,
Jonas

      reply	other threads:[~2026-06-15  7:40 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-08  9:37 [PATCH v2] MIPS: smp: report dying CPU to RCU in stop_this_cpu() Jonas Jelonek
2026-06-10  6:05 ` Huacai Chen
2026-06-15  7:00   ` Jonas Jelonek
2026-06-15  7:09     ` Huacai Chen
2026-06-15  7:16       ` Jonas Jelonek
2026-06-15  7:30         ` Huacai Chen
2026-06-15  7:40           ` Jonas Jelonek [this message]

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