Re: [PATCH v2] MIPS: smp: report dying CPU to RCU in stop_this_cpu()

[Huacai Chen]

On Mon, Jun 15, 2026 at 3:40 PM Jonas Jelonek <jelonek.jonas@xxxxxxxxx> wrote:
>
> 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.
With some hack I also reproduce a similar issue on LoongArch in the
PREEMPT_NONE model.
Reviewed-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>

Huacai

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