linux-kernel - Re: [RFC PATCH 1/4 V2] livedump: Add notifier-call-chain into do_page

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Message-ID: <4FBF77BF.1040304@hitachi.com>
Date:	Fri, 25 May 2012 21:14:55 +0900
From:	YOSHIDA Masanori <masanori.yoshida.tv@...achi.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Vivek Goyal <vgoyal@...hat.com>, linux-kernel@...r.kernel.org,
	Andy Lutomirski <luto@....edu>, Ingo Molnar <mingo@...e.hu>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Kees Cook <keescook@...omium.org>,
	Kevin Hilman <khilman@...com>,
	Prarit Bhargava <prarit@...hat.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Tejun Heo <tj@...nel.org>,
	yrl.pp-manager.tt@...achi.com
Subject: Re: [RFC PATCH 1/4 V2] livedump: Add notifier-call-chain into do_page_fault

Hi, Peter,

I agree that notifier isn't suitable for this purpose.

In the next version, I plan to replace this with a simple
callback as follows.

   if (very_unlikely(under_live_dump))
       ...

In addition to this, since PF handler is a very hot path,
I will cover the condition with "#ifdef CONFIG_WRPROTECT".

Thank you.


On 2012/05/25 18:19, Peter Zijlstra wrote:
> On Fri, 2012-05-25 at 18:12 +0900, YOSHIDA Masanori wrote:
>>
>> This patch adds notifier-call-chain that is called in do_page_fault.
>> Livedump uses this to check if page fault is caused by livedump, and if so,
>> the fault is handled by livedump's handler function. Otherwise, it is
>> handled by the original page fault handler.
>
> No, please no notifiers..
>
>
>

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