[PATCH v2 0/5] ARM: Remaining PREEMPT_RT bits

[Linus Walleij]

On Mon, Nov 3, 2025 at 12:24 PM Arnd Bergmann <arnd at arndb.de> wrote:
> On Mon, Nov 3, 2025, at 11:15, Sebastian Andrzej Siewior wrote:
> > this is the last batch I have to enable PREEMPT_RT on the ARM
> > architecture.
> > Last time I posted them there was some discussion about making the
> > branch predictor hardening worse. I redid it hoping it improved now and
> > does not make it worse.
> >
> > v1…v2: https://lore.kernel.org/all/20251029155918.503060-1-bigeasy@linutronix.de
> >   - Allow to enable jump-labels on UP. The UP build does not involve
> >     stop_machine(). Reworked by Arnd.
> >
> >   - Instead of forbidding HAVE_GUP_FAST with HIGHPTE enabled just
> >     disable HIGHPTE on PREEMPT_RT. As Arnd explained, HIGHPTE is rarely
> >     needed.
> >
> >   - Don't let ARCH_SUPPORTS_RT depend on HAVE_POSIX_CPU_TIMERS_TASK_WORK
> >     which in turn depends on !KVM. Since KVM has been removed from ARM
> >     it is sufficient to unconditionally allow ARCH_SUPPORTS_RT. Noted
> >     by Arnd.
>
> Whole series
>
> Reviewed-by: Arnd Bergmann <arnd at arndb.de>
>
> Looks all good to me. The first two patches may clash with
> the work on generic entry that I think Linus Walleij (added to
> Cc) is in the process of rebasing, but I think that is fine:
> hopefully the special case that you  adding here will just go
> away after Linus' patches, so everything should be fine
> regardless of which gets merged first.
>
> Linus, can you have a look and confirm?

The patches look fine to me, the series:
Acked-by: Linus Walleij <linus.walleij at linaro.org>
(nevermind the kernel.org address on this mail, it's because
the mail is not in my other inbox because of something...)

The generic entry is mainly about getting rid of the old
RCU context tracker and ridding some lockdep warnings and
I am in the process of splitting off the irqentry parts and send
separately.

I think these patches are good to go.

Yours,
Linus Walleij