linux-kernel - Re: [PATCH v2] kernel/panic/kexec: fix "crash_kexec_post

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Message-ID: <87619qzo5d.fsf@x220.int.ebiederm.org>
Date:	Tue, 24 Mar 2015 05:27:10 -0500
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Baoquan He <bhe@...hat.com>,
	Hatayama, Daisuke/畑山 大輔 
	<d.hatayama@...fujitsu.com>, Vivek Goyal <vgoyal@...hat.com>,
	hidehiro.kawai.ez@...achi.com, linux-kernel@...r.kernel.org,
	kexec@...ts.infradead.org, akpm@...ux-foundation.org,
	mingo@...hat.com, bp@...e.de
Subject: Re: [PATCH v2] kernel/panic/kexec: fix "crash_kexec_post_notifiers" option issue in oops path

Ingo Molnar <mingo@...nel.org> writes:

> * Masami Hiramatsu <masami.hiramatsu.pt@...achi.com> wrote:
>
>> > 
>> >   f06e5153f4ae ("kernel/panic.c: add "crash_kexec_post_notifiers" option for kdump after panic_notifers")
>> > 
>> > Was that crash_kexec() was called unconditionally after notifiers were 
>> > called, which should be fixed via the simple patch below (untested). 
>> > Looks much simpler than your fix.
>> 
>> No, Daisuke's patch is not for that case. [...]
>
> Yet the actual bug is in that commit, 'crash_kexec_post_notifiers' was 
> clearly not a no-op in the default case, against expectations.
>
> So the first step should be to restore the original behavior (my 
> patch), then should any new tweaks be added.

Honestly I think the proper fix is to simply revert f06e5153f4ae.

It was clearly not properly tested by the people who wanted it because
they came back quite a while later with additional bleh.

I think this pretty much counts as hitting the code doesn't work let's
remove it threshold.

Eric
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