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From: Arnd Bergmann <arnd@arndb.de>
To: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [RFC PATCH 1/2] arm64: run softirqs on the per-CPU IRQ stack
Date: Thu, 7 Jul 2022 14:58:21 +0200	[thread overview]
Message-ID: <CAK8P3a0h1rFot013raf+O49pvV0JtyBX4Hwp3dt_85jzsJv3ww@mail.gmail.com> (raw)
In-Reply-To: <20220707110511.52129-2-zhengqi.arch@bytedance.com>

On Thu, Jul 7, 2022 at 1:05 PM Qi Zheng <zhengqi.arch@bytedance.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@bytedance.com>

I think this is the correct approach, but your patch conflicts with another
patch I have queued up in the asm-generic tree, see
https://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic.git/commit/?h=asm-generic&id=f2c5092190f21

Please adapt accordingly.

Are there any architectures left that use IRQ stacks but don't
set HAVE_SOFTIRQ_ON_OWN_STACK? If not, we could
also consider removing the Kconfig symbol and just requiring
it to be done this way (for non-PREEMPT_RT).

        Arnd

WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	 Linux ARM <linux-arm-kernel@lists.infradead.org>,
	 Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	 Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [RFC PATCH 1/2] arm64: run softirqs on the per-CPU IRQ stack
Date: Thu, 7 Jul 2022 14:58:21 +0200	[thread overview]
Message-ID: <CAK8P3a0h1rFot013raf+O49pvV0JtyBX4Hwp3dt_85jzsJv3ww@mail.gmail.com> (raw)
In-Reply-To: <20220707110511.52129-2-zhengqi.arch@bytedance.com>

On Thu, Jul 7, 2022 at 1:05 PM Qi Zheng <zhengqi.arch@bytedance.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@bytedance.com>

I think this is the correct approach, but your patch conflicts with another
patch I have queued up in the asm-generic tree, see
https://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic.git/commit/?h=asm-generic&id=f2c5092190f21

Please adapt accordingly.

Are there any architectures left that use IRQ stacks but don't
set HAVE_SOFTIRQ_ON_OWN_STACK? If not, we could
also consider removing the Kconfig symbol and just requiring
it to be done this way (for non-PREEMPT_RT).

        Arnd

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2022-07-07 12:58 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-07 11:05 [RFC PATCH 0/2] arm64: run softirqs on the per-CPU IRQ stack Qi Zheng
2022-07-07 11:05 ` Qi Zheng
2022-07-07 11:05 ` [RFC PATCH 1/2] " Qi Zheng
2022-07-07 11:05   ` Qi Zheng
2022-07-07 12:58   ` Arnd Bergmann [this message]
2022-07-07 12:58     ` Arnd Bergmann
2022-07-07 13:43     ` Qi Zheng
2022-07-07 13:43       ` Qi Zheng
2022-07-07 13:53       ` Arnd Bergmann
2022-07-07 13:53         ` Arnd Bergmann
2022-07-07 15:05         ` Qi Zheng
2022-07-07 15:05           ` Qi Zheng
2022-07-08  2:56   ` kernel test robot
2022-07-07 11:05 ` [RFC PATCH 2/2] arm64: support HAVE_IRQ_EXIT_ON_IRQ_STACK Qi Zheng
2022-07-07 11:05   ` Qi Zheng
2022-07-07 12:49   ` Arnd Bergmann
2022-07-07 12:49     ` Arnd Bergmann
2022-07-07 13:38     ` Qi Zheng
2022-07-07 13:38       ` Qi Zheng
2022-07-07 14:41       ` Arnd Bergmann
2022-07-07 14:41         ` Arnd Bergmann
2022-07-07 15:00         ` Qi Zheng
2022-07-07 15:00           ` Qi Zheng
2022-07-07 20:55           ` Arnd Bergmann
2022-07-07 20:55             ` Arnd Bergmann
2022-07-08  3:13             ` Qi Zheng
2022-07-08  3:13               ` Qi Zheng
2022-07-08  8:52               ` Arnd Bergmann
2022-07-08  8:52                 ` Arnd Bergmann
2022-07-08  9:13                 ` Qi Zheng
2022-07-08  9:13                   ` Qi Zheng

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