From: David Laight <David.Laight@ACULAB.COM>
To: 'Josh Poimboeuf' <jpoimboe@redhat.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Ingo Molnar <mingo@kernel.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Andy Lutomirski" <luto@amacapital.net>,
Borislav Petkov <bp@suse.de>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: RE: [PATCH] x86: Avoid pr_cont() in show_opcodes()
Date: Tue, 10 Jul 2018 16:51:53 +0000 [thread overview]
Message-ID: <cbb4e190f9de45cf8586c1df02ec3619@AcuMS.aculab.com> (raw)
In-Reply-To: <20180709191034.pyadc3cy7ulwaf2o@treble>
From: Josh Poimboeuf
> Sent: 09 July 2018 20:12
> On Mon, Jul 09, 2018 at 10:49:53AM +0200, Peter Zijlstra wrote:
> > On Sat, Jul 07, 2018 at 10:54:28PM +0900, Tetsuo Handa wrote:
> > > >> Since syzbot is confused by concurrent printk() messages [1],
> > > >> this patch changes show_opcodes() to use snprintf().
> >
> > But how big of a problem is that really? We can't very well remove all
> > pr_cont stuff from the kernel.
>
> I'd say we should try to make oopses as legible as possible.
To make oopses legible you need to lock the output between output lines.
Which would require a 'KERN_CONTINUED' marker on the previous print.
> Also KERN_CONT is inherently broken, and we should avoid using it in
> general, IMO.
I'm sure something semi-automatic could be done to expect a further
print if the line doesn't end in '\n'.
A per-cpu line buffer is probably excessive, but some kind of
timing out lock might work (release expecting re-acquire).
David
next prev parent reply other threads:[~2018-07-10 16:50 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-07 6:07 [PATCH] x86: Avoid pr_cont() in show_opcodes() Tetsuo Handa
2018-07-07 11:12 ` Ingo Molnar
2018-07-07 13:54 ` Tetsuo Handa
2018-07-09 8:49 ` Peter Zijlstra
2018-07-09 13:22 ` David Laight
2018-07-09 19:11 ` Josh Poimboeuf
2018-07-10 11:55 ` Tetsuo Handa
2018-07-10 16:51 ` David Laight [this message]
2018-07-10 21:08 ` Tetsuo Handa
2018-07-16 12:47 ` Tetsuo Handa
2018-07-17 9:01 ` Rasmus Villemoes
2018-07-17 13:53 ` Tetsuo Handa
2018-07-17 14:24 ` Rasmus Villemoes
2018-07-17 20:54 ` Tetsuo Handa
2018-07-17 21:19 ` Joe Perches
2018-07-18 8:41 ` Joe Perches
2018-07-17 21:07 ` Andy Shevchenko
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