From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752287AbbH0J35 (ORCPT ); Thu, 27 Aug 2015 05:29:57 -0400 Received: from mx2.suse.de ([195.135.220.15]:48843 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751549AbbH0J3z (ORCPT ); Thu, 27 Aug 2015 05:29:55 -0400 Subject: Re: [PATCH V3] mm: memory hot-add: memory can not be added to movable zone defaultly To: Changsheng Liu , akpm@linux-foundation.org, isimatu.yasuaki@jp.fujitsu.com References: <1440665641-3839-1-git-send-email-liuchangsheng@inspur.com> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, wunan@inspur.com, yanxiaofeng@inspur.com, fandd@inspur.com, Changsheng Liu From: Vlastimil Babka Message-ID: <55DED890.4020200@suse.cz> Date: Thu, 27 Aug 2015 11:29:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <1440665641-3839-1-git-send-email-liuchangsheng@inspur.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/27/2015 10:54 AM, Changsheng Liu wrote: > From: Changsheng Liu > > After the user config CONFIG_MOVABLE_NODE and movable_node kernel option, > When the memory is hot added, should_add_memory_movable() return 0 > because all zones including movable zone are empty, > so the memory that was hot added will be added to the normal zone > and the normal zone will be created firstly. > But we want the whole node to be added to movable zone defaultly. OK it seems current behavior indeed goes against the expectations of setting movable_node. > So we change should_add_memory_movable(): if the user config > CONFIG_MOVABLE_NODE and movable_node kernel option > it will always return 1 and all zones is empty at the same time, > so that the movable zone will be created firstly > and then the whole node will be added to movable zone defaultly. > If we want the node to be added to normal zone, > we can do it as follows: > "echo online_kernel > /sys/devices/system/memory/memoryXXX/state" > > If the memory is added to movable zone defaultly, > the user can offline it and add it to other zone again. Was this tested to really work as well? Per Yasuaki's explanation in v2, you shouldn't create ZONE_MOVABLE before ZONE_NORMAL. > But if the memory is added to normal zone defaultly, > the user will not offline the memory used by kernel. > > Reviewed-by: Andrew Morton Interesting... > Signed-off-by: Changsheng Liu i > Tested-by: Dongdong Fan > --- > mm/memory_hotplug.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 26fbba7..b5f14fa 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1198,6 +1198,9 @@ static int should_add_memory_movable(int nid, u64 start, u64 size) > pg_data_t *pgdat = NODE_DATA(nid); > struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE; > > + if (movable_node_is_enabled()) > + return 1; > + > if (zone_is_empty(movable_zone)) > return 0; > >