linux-kernel - Re: Oops caused by race between livepatch and ftrace

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Message-ID: <20190520214801.GD1646@sventech.com>
Date:   Mon, 20 May 2019 14:48:02 -0700
From:   Johannes Erdfelt <johannes@...felt.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Joe Lawrence <joe.lawrence@...hat.com>,
        Jessica Yu <jeyu@...nel.org>, Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>, live-patching@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: Oops caused by race between livepatch and ftrace

On Mon, May 20, 2019, Josh Poimboeuf <jpoimboe@...hat.com> wrote:
> I think you must have been looking at an old version.
> 
> [(v5.2-rc1)] ~/git/linux $ grep jeyu MAINTAINERS
> M:	Jessica Yu <jeyu@...nel.org>

Operator error on my part. I was looking at a different directory with
an old branch checked out. Sorry!

> Can you try this patch (completely untested)?

It seems to be working fine for me. No crashes in a loop for a few
minutes, when it would usually only take a couple of tries to reproduce
the issue for me.

I'll see if I can better reproduce the race from the ftrace side since
every crash I have seen for this issue has been in apply_relocate_add
on the livepatch side.

JE