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

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Message-ID: <20181127021608.pt3ghjjvu2xiy6gq@shbuild888>
Date:   Tue, 27 Nov 2018 10:16:08 +0800
From:   Feng Tang <feng.tang@...el.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
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>, feng.tang@...el.com
Subject: Re: [RFC PATCH] panic: Add options to dump system info when panic
 happens

Hi Andrew,

Thanks for the review.

On Mon, Nov 26, 2018 at 03:24:57PM -0800, Andrew Morton wrote:
> 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.

Will add these info in v2.

> 
> > --- 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?

Thanks for the suggestion, will change it in v2.

- Feng