linux-kernel - Re: [PATCH V2] Documentation: Improve crash_kexec_post

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Message-ID: <ZuI7qkE/6EVEGajs@MiWiFi-R3L-srv>
Date: Thu, 12 Sep 2024 08:54:02 +0800
From: Baoquan He <bhe@...hat.com>
To: "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Cc: kexec@...ts.infradead.org, linux-doc@...r.kernel.org, vgoyal@...hat.com,
	dyoung@...hat.com, corbet@....net, linux-kernel@...r.kernel.org,
	linux-debuggers@...r.kernel.org, stephen.s.brennan@...cle.com,
	kernel@...ccoli.net, kernel-dev@...lia.com
Subject: Re: [PATCH V2] Documentation: Improve crash_kexec_post_notifiers
 description

On 09/11/24 at 05:09pm, Guilherme G. Piccoli wrote:
> On 02/09/2024 05:05, Baoquan He wrote:
> > On 08/30/24 at 03:21pm, Guilherme G. Piccoli wrote:
> >> Be more clear about the downsides, the upsides (yes, there are some!)
> >> and about code that unconditionally sets that.
> >>
> >> Reviewed-by: Stephen Brennan <stephen.s.brennan@...cle.com>
> >> Signed-off-by: Guilherme G. Piccoli <gpiccoli@...lia.com>
> >>
> >> ---
> >>
> >> V2: Some wording improvements from Stephen, thanks!
> >> Also added his review tag.
> >>
> >> V1 link: https://lore.kernel.org/r/20240830140401.458542-1-gpiccoli@igalia.com/
> >>
> >>
> >>  Documentation/admin-guide/kernel-parameters.txt | 16 ++++++++++------
> >>  1 file changed, 10 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> >> index efc52ddc6864..351730108c58 100644
> >> --- a/Documentation/admin-guide/kernel-parameters.txt
> >> +++ b/Documentation/admin-guide/kernel-parameters.txt
> >> @@ -913,12 +913,16 @@
> >>  			the parameter has no effect.
> >>  
> >>  	crash_kexec_post_notifiers
> >> -			Run kdump after running panic-notifiers and dumping
> >> -			kmsg. This only for the users who doubt kdump always
> >> -			succeeds in any situation.
> >> -			Note that this also increases risks of kdump failure,
> >> -			because some panic notifiers can make the crashed
> >> -			kernel more unstable.
> >> +			Only jump to kdump kernel after running the panic
> >> +			notifiers and dumping kmsg. This option increases the
> >> +			risks of a kdump failure, since some panic notifiers
> >> +			can make the crashed kernel more unstable. In the
> >> +			configurations where kdump may not be reliable,
> >> +			running the panic notifiers can allow collecting more
> >> +			data on dmesg, like stack traces from other CPUS or
> >> +			extra data dumped by panic_print. Notice that some
> >> +			code enables this option unconditionally, like
> >> +			Hyper-V, PowerPC (fadump) and AMD SEV.
> >                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > I know Hyper-V enable panic-notifiers by default, but don't remember how
> > PowerPC and AMD SEC behave in this aspect. While at it, can you add a
> > little more words to state them in log so that people can learn it?
> > Thanks.
> > 
> Hi Baoquan, tnx for the suggestion! You mean mention that in the commit
> message? If so, I can certainly do - will sent a new version soon(tm)
> and include it =)

You are right, thanks for the effort.