linux-kernel - Re: [BUG] I found a bug when try to enable record

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Message-ID: <202106091110.F13B8B6@keescook>
Date:   Wed, 9 Jun 2021 11:12:22 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Joel Fernandes <joel@...lfernandes.org>
Cc:     "Zhengyejian (Zetta)" <zhengyejian1@...wei.com>,
        rostedt@...dmis.org, ccross@...roid.com,
        linux-kernel@...r.kernel.org, Zhangjinhao <zhangjinhao2@...wei.com>
Subject: Re: [BUG] I found a bug when try to enable record_ftrace

On Tue, Jun 08, 2021 at 03:16:44PM -0400, Joel Fernandes wrote:
> On Wed, Jun 02, 2021 at 10:43:29AM -0700, Kees Cook wrote:
> > 
> > On Wed, Jun 02, 2021 at 03:42:23PM +0800, Zhengyejian (Zetta) wrote:
> > > Hello,
> > > 
> > > There may be a deadlock caused by ftrace recursion when try to enable
> > > record_ftrace.
> > 
> > Hi,
> > 
> > Thanks for the report. Joel, is this something you can take a look at?
> 
> Kees,
> 
> Sorry for late reply. Right now I am dealing with a production-stop bug and
> would not likely get time. Plus I feel a bit less motivated, because the
> ftrace in pstore the way it stands now is unusable due to perf issues anyway
> (I wonder if anyone uses it at all now). I would rather someone who has time
> to work on this try to revive: https://lkml.org/lkml/2020/9/2/1075 . Should
> we just delete pstore function tracing till then?

If no one is using it, then yes, let's rip it out. Zetta, are you using
pstore ftrace?

-Kees

-- 
Kees Cook