From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 3519D600365 for ; Tue, 27 Jul 2010 06:01:16 -0400 (EDT) Received: by iwn2 with SMTP id 2so4336252iwn.14 for ; Tue, 27 Jul 2010 03:01:15 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20100727171351.98d5fb60.kamezawa.hiroyu@jp.fujitsu.com> References: <1280159163-23386-1-git-send-email-minchan.kim@gmail.com> <20100727171351.98d5fb60.kamezawa.hiroyu@jp.fujitsu.com> Date: Tue, 27 Jul 2010 19:01:14 +0900 Message-ID: Subject: Re: [PATCH] Tight check of pfn_valid on sparsemem - v4 From: Minchan Kim Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Milton Miller , Christoph Lameter , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Russell King , Mel Gorman , Johannes Weiner , Kukjin Kim List-ID: Hi, Kame. On Tue, Jul 27, 2010 at 5:13 PM, KAMEZAWA Hiroyuki >> Perhaps the mem_section array. =A0Using a symbol that is part of >> the model pre-checks can remove a global symbol lookup and has the side >> effect of making sure our pfn_valid is for the right model. >> > > But yes, maybe it's good to make use of a fixed-(magic)-value. fixed-magic-value? Yes. It can be good for some debugging. But as Christoph pointed out, we need some strict check(ex, PG_reserved) for preventing unlucky valid using of magic value in future. But in fact I have a concern to use PG_reserved since it can be used afterward pfn_valid normally to check hole in non-hole system. So I think it's redundant. Hmm.. --=20 Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org