linux-kernel - Re: [RFC PATCH] panic: Add options to dump system info when panic happens

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Message-Id: <20181126152457.42f9917138e02b4ab9f17f7b@linux-foundation.org>
Date:   Mon, 26 Nov 2018 15:24:57 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Feng Tang <feng.tang@...el.com>
Cc:     linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        John Stultz <john.stultz@...aro.org>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [RFC PATCH] panic: Add options to dump system info when panic
 happens

On Thu, 22 Nov 2018 15:10:31 +0800 Feng Tang <feng.tang@...el.com> wrote:

> Kernel panic issues are always painful to debug, partially
> because of it's not easy to get enough information of the
> context when panic happens.
> 
> And we have ramoops and kdump for that, while this commit
> tries to a easier way to show the system info by adding a
> cmdline parameter, referring some idea from sysrq handler.
> 

This seems sensible to me.

> This patch is frequently used by us when debugging panic and system
> stability bugs, and does help much. And the options could be expanded
> more to cover other info like the ftrace, signal etc.

And that info is valuable.

> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3081,6 +3081,13 @@
>  			timeout < 0: reboot immediately
>  			Format: <timeout>
>  
> +	panic_dump=	Bitmask for dumping system info when panic happens.
> +			User can chose combination of the following bits:
> +			bit 0: dump all tasks info
> +			bit 1: dump system memory info
> +			bit 2: dump timer info
> +			bit 3: dump locks info if CONFIG_LOCKDEP is on
> +

Using "dump" makes this feature sounds a bit like kdump, which is also
used in this code context.

I think I'd prefer that we use "print" - that's a more accurate
description and avoids such confusion.  So s/dump/print/ and
s/DUMP/PRINT/ throughout the changelog and patch?