linux-kernel - Re: [PATCH v10 03/11] arm64: Make get_wchan() use arch_stack

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Message-ID: <YXA/eepRCCzL+/jD@sirena.org.uk>
Date:   Wed, 20 Oct 2021 17:10:33 +0100
From:   Mark Brown <broonie@...nel.org>
To:     madvenka@...ux.microsoft.com
Cc:     mark.rutland@....com, jpoimboe@...hat.com, ardb@...nel.org,
        nobuta.keiya@...itsu.com, sjitindarsingh@...il.com,
        catalin.marinas@....com, will@...nel.org, jmorris@...ei.org,
        linux-arm-kernel@...ts.infradead.org,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 03/11] arm64: Make get_wchan() use arch_stack_walk()

On Thu, Oct 14, 2021 at 09:58:39PM -0500, madvenka@...ux.microsoft.com wrote:
> From: "Madhavan T. Venkataraman" <madvenka@...ux.microsoft.com>
> 
> Currently, get_wchan() in ARM64 code walks the stack using start_backtrace()
> and unwind_frame(). Make it use arch_stack_walk() instead. This makes
> maintenance easier.

This overlaps with some very similar updates that Peter Zijlstra is
working on which addresses some existing problems with wchan:

	https://lore.kernel.org/all/20211008111527.438276127@infradead.org/

It probably makes sense for you to coordinate with Peter here, some of
that series is already merged up to his patch 6 which looks very
similar to what you've got here.  In that thread you'll see that Mark
Rutland spotted an issue with the handling of __switch_to() on arm64
which probably also applies to your change.

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