linux-kernel - Re: [patch V4 part 1 29/36] x86/mce: Send #MC singal from task work

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Date:   Wed, 13 May 2020 19:42:17 -0400 (EDT)
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>,
        paulmck <paulmck@...nel.org>, Andy Lutomirski <luto@...nel.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>, rostedt <rostedt@...dmis.org>,
        "Joel Fernandes, Google" <joel@...lfernandes.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [patch V4 part 1 29/36] x86/mce: Send #MC singal from task work

----- On May 5, 2020, at 9:16 AM, Thomas Gleixner tglx@...utronix.de wrote:

> From: Peter Zijlstra <peterz@...radead.org>
> 

Patch title: singal -> signal.

> Convert #MC over to using task_work_add(); it will run the same code
> slightly later, on the return to user path of the same exception.

So I suspect that switching the order between tracehook_notify_resume()
(which ends up calling task_work_run()) and do_signal() done by an
earlier patch in this series intends to ensure the information about the
instruction pointer causing the #MC is not overwritten by do_signal()
(but I'm just guessing).

If it's the case, I think it should be clearly stated as the intent of the
earlier patch.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com