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Date: Tue, 6 May 2014 08:26:04 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@kernel.org>, Frederic Weisbecker <fweisbec@gmail.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Seth Jennings <sjenning@redhat.com>, Ingo Molnar <mingo@redhat.com>,
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        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC PATCH 0/2] kpatch: dynamic kernel patching
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On Tue, 06 May 2014 20:45:50 +0900
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:


> However, I also think if users can accept such freezing wait-time,
> it means they can also accept kexec based "checkpoint-restart" patching.
> So, I think the final goal of the kpatch will be live patching without
> stopping the machine. I'm discussing the issue on github #138, but that is
> off-topic. :)
> 

I agree with Ingo too. Being conservative at first is the right
approach here. We should start out with a stop_machine making sure that
everything is sane before we continue. Sure, that's not much different
than a kexec, but lets take things one step at a time.

ftrace did the stop_machine (and still does for some archs), and slowly
moved to a more efficient method. kpatch/kgraft should follow suit.

-- Steve