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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Fri, 5 Aug 2022 09:50:00 +0200
Message-ID: <CAK8P3a1NmgTEiXDgYyXzAsBDj9cW5_Km=VRyrOX_Sr4dJ1aknw@mail.gmail.com>
Subject: Re: [PATCH v2] arm64: run softirqs on the per-CPU IRQ stack
To:     Qi Zheng <zhengqi.arch@bytedance.com>
Cc:     Will Deacon <will@kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Mark Rutland <mark.rutland@arm.com>
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On Fri, Aug 5, 2022 at 9:10 AM Qi Zheng <zhengqi.arch@bytedance.com> wrote:
> On 2022/8/2 14:53, Qi Zheng wrote:
> > Currently arm64 supports per-CPU IRQ stack, but softirqs
> > are still handled in the task context.
> >
> > Since any call to local_bh_enable() at any level in the task's
> > call stack may trigger a softirq processing run, which could
> > potentially cause a task stack overflow if the combined stack
> > footprints exceed the stack's size, let's run these softirqs
> > on the IRQ stack as well.
> >
> > Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> > Reviewed-by: Arnd Bergmann <arnd@arndb.de>
> > Acked-by: Will Deacon <will@kernel.org>
>
> Are we good to merge it into 6.0-rc1?

I think you misunderstood the timing that Will proposed in

https://lore.kernel.org/linux-arm-kernel/d540aaff-ec6a-3f25-dd79-b27b4ad81b36@bytedance.com/

You should send your patch after 6.0-rc1 has been released, to be merged
into the linux-next tree and sent as part of the 6.1 merge window.

The two ways patches get merged are:

- bugfixes can get merged into maintainer trees at any time and sent
  upstream regardless of the merge window, these never need to wait

- non-bugfix patches can get merged into maintainer trees based on an
   -rc release and then sent upstream during the following merge window.

        Arnd