Re: [RFC PATCH 0/2] kpatch: dynamic kernel patching

[Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>]

(2014/05/06 21:26), Steven Rostedt wrote:
> 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.

Agreed. that is a correct way to move things forward.
Anyway, my stop_machine-less approach still has many implementation
issues. It should be solved in upstream, not out-of-tree. So, this
topic is off-topic at this stage. :) We need to focus on how to
merge live-patch into upstream kernel.

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

Sure, that's a best story of how things should be evolved on the kernel :)

Thank you,

-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com