Re: [PATCH v2] twist: allow converting pr_devel()/pr_debug() into snprintf()

From: Petr Mladek <pmladek@suse.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Dmitry Vyukov <dvyukov@google.com>,
	Ondrej Mosnacek <omosnace@redhat.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH v2] twist: allow converting pr_devel()/pr_debug() into snprintf()
Date: Fri, 29 May 2020 10:17:48 +0200	[thread overview]
Message-ID: <20200529081748.GC27273@linux-b0ei> (raw)
In-Reply-To: <CAHk-=wgz=7MGxxX-tmMmdCsKyYJkuyxNc-4uLP=e_eEV=OzUaw@mail.gmail.com>

On Thu 2020-05-28 12:50:35, Linus Torvalds wrote:
> On Thu, May 28, 2020 at 8:17 AM Tetsuo Handa
> <penguin-kernel@i-love.sakura.ne.jp> wrote:
> >
> > CONFIG_TWIST_FOR_SYZKALLER_TESTING is meant for linux-next only.
> > But CONFIG_TWIST_KERNEL_BEHAVIOR is meant for Linus's tree.
> 
> I really absolutely still detest this all. I don't see the point. The
> naming is completely random (both "twist" and then options like
> "TWIST_FOR_SYZKALLER_TESTING" that have no conceptual meaning.
>
> I still don't understand why this small set of random options couldn't
> just be kernel options that get set on the command line, and that have
> independent and sane and explainable behavior? Why this odd mentality
> of "syzkaller is special"?

I am afraid that many of them could not be normal options. They change or
break some behavior that is necessary by seriously used system.

> I've complained about this whole thing before. I'm getting really fed
> up with this whole concept of "magic crazy config options".

Just to make my role clear in this saga.

I am focused on the change of pr_debug() behavior. I do _not_ believe
that it is worth it. But I wanted to give fuzzer guys a chance to get
some data.

This is why I offered to push hacky patch into linux-next via printk
tree to get fuzzers fed. Such a patch would change the behavior only
for the fuzzer (with the crazy config enabled) and it would be there
only for a limited time.

I personally do _not_ have a good feeling about having such hacks in
upstream kernel. But I do not feel in position to decide about it.
I wanted to solve this question later if there would have been
anything to upstream.

I am _not_ going to push any twists, in the current form,
upstream via printk tree.

Best Regards,
Petr