From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752933Ab0IBFuW (ORCPT ); Thu, 2 Sep 2010 01:50:22 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:46883 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751039Ab0IBFuV (ORCPT ); Thu, 2 Sep 2010 01:50:21 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Thu, 2 Sep 2010 14:45:00 +0900 From: KAMEZAWA Hiroyuki To: Michal Hocko Cc: Wu Fengguang , "linux-mm@kvack.org" , Andrew Morton , "Kleen, Andi" , Haicheng Li , Christoph Lameter , "linux-kernel@vger.kernel.org" , Mel Gorman Subject: Re: [PATCH] Make is_mem_section_removable more conformable with offlining code Message-Id: <20100902144500.a0d05b08.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100901124138.GD6663@tiehlicka.suse.cz> References: <20100820141400.GD4636@tiehlicka.suse.cz> <20100822004232.GA11007@localhost> <20100823092246.GA25772@tiehlicka.suse.cz> <20100831141942.GA30353@localhost> <20100901121951.GC6663@tiehlicka.suse.cz> <20100901124138.GD6663@tiehlicka.suse.cz> Organization: FUJITSU Co. 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X-Mailer: Sylpheed 3.0.3 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 1 Sep 2010 14:41:38 +0200 Michal Hocko wrote: > On Wed 01-09-10 14:19:51, Michal Hocko wrote: > > On Tue 31-08-10 22:19:42, Wu Fengguang wrote: > > > On Mon, Aug 23, 2010 at 05:22:46PM +0800, Michal Hocko wrote: > > > > On Sun 22-08-10 08:42:32, Wu Fengguang wrote: > > > > > Hi Michal, > > > > > > > > Hi, > > > > > > > > > > > > > > It helps to explain in changelog/code > > > > > > > > > > - in what situation a ZONE_MOVABLE will contain !MIGRATE_MOVABLE > > > > > pages? > > > > > > > > page can be MIGRATE_RESERVE IIUC. > > > > > > Yup, it may also be set to MIGRATE_ISOLATE by soft_offline_page(). > > > > Doesn't it make sense to check for !MIGRATE_UNMOVABLE then? > > Something like the following patch. > > > From de85f1aa42115678d3340f0448cd798577036496 Mon Sep 17 00:00:00 2001 > From: Michal Hocko > Date: Fri, 20 Aug 2010 15:39:16 +0200 > Subject: [PATCH] Make is_mem_section_removable more conformable with offlining code > > Currently is_mem_section_removable checks whether each pageblock from > the given pfn range is of MIGRATE_MOVABLE type or if it is free. If both > are false then the range is considered non removable. > > On the other hand, offlining code (more specifically > set_migratetype_isolate) doesn't care whether a page is free and instead > it just checks the migrate type of the page and whether the page's zone > is movable. > > This can lead into a situation when we can mark a node as not removable > just because a pageblock is MIGRATE_RESERVE and it is not free. > > Let's make a common helper is_page_removable which unifies both tests > at one place. Also let's check for MIGRATE_UNMOVABLE rather than all > possible MIGRATEable types. > > Signed-off-by: Michal Hocko Hmm..Why MIGRATE_RECLAIMABLE is included ? If MIGRATE_RCLAIMABLE is included, set_migrate_type() should check the range of pages. Because it makes the pageblock as MIGRAGE_MOVABLE after failure of memory hotplug. Original code checks. - the range is MIGRAGE_MOVABLE or - the range includes only free pages and LRU pages. Then, moving them back to MIGRAGE_MOVABLE after failure was correct. Doesn't this makes changes MIGRATE_RECALIMABLE to be MIGRATE_MOVABLE and leads us to more fragmentated situation ? Thanks, -Kame From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 8E2AC6B004A for ; Thu, 2 Sep 2010 01:50:20 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o825oHJv003728 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 2 Sep 2010 14:50:17 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 0545D45DE53 for ; Thu, 2 Sep 2010 14:50:17 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id CAB7245DE4D for ; Thu, 2 Sep 2010 14:50:16 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id AE3D51DB803F for ; Thu, 2 Sep 2010 14:50:16 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 540531DB803C for ; Thu, 2 Sep 2010 14:50:13 +0900 (JST) Date: Thu, 2 Sep 2010 14:45:00 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH] Make is_mem_section_removable more conformable with offlining code Message-Id: <20100902144500.a0d05b08.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100901124138.GD6663@tiehlicka.suse.cz> References: <20100820141400.GD4636@tiehlicka.suse.cz> <20100822004232.GA11007@localhost> <20100823092246.GA25772@tiehlicka.suse.cz> <20100831141942.GA30353@localhost> <20100901121951.GC6663@tiehlicka.suse.cz> <20100901124138.GD6663@tiehlicka.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Michal Hocko Cc: Wu Fengguang , "linux-mm@kvack.org" , Andrew Morton , "Kleen, Andi" , Haicheng Li , Christoph Lameter , "linux-kernel@vger.kernel.org" , Mel Gorman List-ID: On Wed, 1 Sep 2010 14:41:38 +0200 Michal Hocko wrote: > On Wed 01-09-10 14:19:51, Michal Hocko wrote: > > On Tue 31-08-10 22:19:42, Wu Fengguang wrote: > > > On Mon, Aug 23, 2010 at 05:22:46PM +0800, Michal Hocko wrote: > > > > On Sun 22-08-10 08:42:32, Wu Fengguang wrote: > > > > > Hi Michal, > > > > > > > > Hi, > > > > > > > > > > > > > > It helps to explain in changelog/code > > > > > > > > > > - in what situation a ZONE_MOVABLE will contain !MIGRATE_MOVABLE > > > > > pages? > > > > > > > > page can be MIGRATE_RESERVE IIUC. > > > > > > Yup, it may also be set to MIGRATE_ISOLATE by soft_offline_page(). > > > > Doesn't it make sense to check for !MIGRATE_UNMOVABLE then? > > Something like the following patch. > > > From de85f1aa42115678d3340f0448cd798577036496 Mon Sep 17 00:00:00 2001 > From: Michal Hocko > Date: Fri, 20 Aug 2010 15:39:16 +0200 > Subject: [PATCH] Make is_mem_section_removable more conformable with offlining code > > Currently is_mem_section_removable checks whether each pageblock from > the given pfn range is of MIGRATE_MOVABLE type or if it is free. If both > are false then the range is considered non removable. > > On the other hand, offlining code (more specifically > set_migratetype_isolate) doesn't care whether a page is free and instead > it just checks the migrate type of the page and whether the page's zone > is movable. > > This can lead into a situation when we can mark a node as not removable > just because a pageblock is MIGRATE_RESERVE and it is not free. > > Let's make a common helper is_page_removable which unifies both tests > at one place. Also let's check for MIGRATE_UNMOVABLE rather than all > possible MIGRATEable types. > > Signed-off-by: Michal Hocko Hmm..Why MIGRATE_RECLAIMABLE is included ? If MIGRATE_RCLAIMABLE is included, set_migrate_type() should check the range of pages. Because it makes the pageblock as MIGRAGE_MOVABLE after failure of memory hotplug. Original code checks. - the range is MIGRAGE_MOVABLE or - the range includes only free pages and LRU pages. Then, moving them back to MIGRAGE_MOVABLE after failure was correct. Doesn't this makes changes MIGRATE_RECALIMABLE to be MIGRATE_MOVABLE and leads us to more fragmentated situation ? Thanks, -Kame -- 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