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Subject: Re: printk: preempt_disable with long time resulting in
 softlockup/RCU stall issues
From: Joe Perches <joe@perches.com>
To: "Luis R. Rodriguez" <mcgrof@suse.com>
Cc: Gavin Hu <gavin.hu.2010@gmail.com>, Petr Mladek <pmladek@suse.com>,
        linux-kernel@vger.kernel.org, Alex Elder <elder@linaro.org>,
        "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>,
        Peter Hurley <peter@hurleysoftware.com>, Tejun Heo <tj@kernel.org>,
        cxie4@marvell.com, cldu@marvell.com, xjian@marvell.com,
        fswu@marvell.com, Jan Kara <jack@suse.cz>
Date: Wed, 08 Jul 2015 10:35:29 -0700
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On Wed, 2015-07-08 at 19:04 +0200, Luis R. Rodriguez wrote:
> On Wed, Jul 08, 2015 at 05:08:35PM +0800, Gavin Hu wrote:
> > Hi,
> > 
> > Yes. We should disable the printk_limit feature when panic to avoid missing
> > messages.
> 
> Sounds like you have been looking into it and have a good idea of what you
> want to do, why not try it and send some RFC patches ?
> 
> While at it, then we could consider doing different things depending on the
> message type. KERN_EMERG would disable preemption, whereas KERN_INFO may not be
> so critical to require it.

That might be a bit difficult to implement with complete correctness
given KERN_EMERG use and continuation lines.