linux-kernel - Re: [PATCH 1/2] watchdog: Fix output

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Message-ID: <20160318164441.GI6344@twins.programming.kicks-ass.net>
Date:	Fri, 18 Mar 2016 17:44:41 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Don Zickus <dzickus@...hat.com>
Cc:	linux-kernel@...r.kernel.org, rostedt@...dmis.org,
	mingo@...nel.org, tglx@...utronix.de
Subject: Re: [PATCH 1/2] watchdog: Fix output

On Fri, Mar 18, 2016 at 12:37:48PM -0400, Don Zickus wrote:
> On Fri, Mar 18, 2016 at 04:28:03PM +0100, Peter Zijlstra wrote:
> > The pr_crap() functions generate idiotic output; use printk().
> > 
> > Broken output:
> > 
> > [ 3538.718135] NMI watchdog: BUG: soft lockup - CPU#2 stuck for 22s!  [perf_fuzzer:2646]
> > [ 3383.233583] NMI watchdog: Watchdog detected hard LOCKUP on cpu 27
> > 
> > Fixed output:
> > 
> > [14180.328194] BUG: soft lockup - CPU#2 stuck for 23s!  [perf_fuzzer:13650]
> > [ 1064.914925] BUG: NMI Watchdog detected hard LOCKUP on cpu 11
> 
> Would something like this be a better patch?

> -#define pr_fmt(fmt) "NMI watchdog: " fmt
> +#define pr_fmt(fmt) "Lockup detector: " fmt

> -		pr_emerg("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
> +		pr_emerg("Detected hard LOCKUP on cpu %d", this_cpu);

That still results in something like:

	Lockup detector: Detected hard LOCKUP on cpu 22

Which is still weird, doesn't mention NMI nor BUG (and when the NMI
triggers it really rather frequently is a dead system).