linux-kernel - Re: [PATCH v1 1/2] arm64: run softirqs on the per-CPU IRQ stack

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Date:   Thu, 14 Jul 2022 13:32:30 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Qi Zheng <zhengqi.arch@...edance.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 1/2] arm64: run softirqs on the per-CPU IRQ stack

On Fri, Jul 8, 2022 at 11:49 AM Qi Zheng <zhengqi.arch@...edance.com> 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@...edance.com>

This seems like a nice improvement, and this version addresses
my concern I raised on the RFC version.

Reviewed-by: Arnd Bergmann <arnd@...db.de>