linux-kernel - Re: [PATCH v5 1/4] printk/nmi: generic solution for safe printk in NMI

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Date:   Thu, 27 Apr 2017 10:31:18 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Russell King <rmk+kernel@....linux.org.uk>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jiri Kosina <jkosina@...e.com>, Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Chris Metcalf <cmetcalf@...hip.com>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-arm-kernel@...ts.infradead.org,
        adi-buildroot-devel@...ts.sourceforge.net,
        linux-cris-kernel@...s.com, linux-mips@...ux-mips.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
        Jan Kara <jack@...e.cz>, Ralf Baechle <ralf@...ux-mips.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        David Miller <davem@...emloft.net>
Subject: Re: [PATCH v5 1/4] printk/nmi: generic solution for safe printk in
 NMI

On Thu, 27 Apr 2017 15:38:19 +0200
Petr Mladek <pmladek@...e.com> wrote:

> > by the way,
> > does this `nmi_print_seq' bypass even fix anything for Steven?  
> 
> I think that this is the most important question.
> 
> Steven, does the patch from
> https://lkml.kernel.org/r/20170420131154.GL3452@pathway.suse.cz
> help you to see the debug messages, please?

You'll have to wait for a bit. The box that I was debugging takes 45
minutes to reboot. And I don't have much more time to play on it before
I have to give it back. I already found the bug I was looking for and
I'm trying not to crash it again (due to the huge bring up time).

When I get a chance, I'll see if I can insert a trigger to crash the
kernel from NMI on another box and see if this patch helps.

Thanks,

-- Steve