From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755323AbbHYNMY (ORCPT ); Tue, 25 Aug 2015 09:12:24 -0400 Received: from mail-qg0-f53.google.com ([209.85.192.53]:36468 "EHLO mail-qg0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751726AbbHYNMW (ORCPT ); Tue, 25 Aug 2015 09:12:22 -0400 Message-ID: <55dc69b5.46268c0a.faa78.24eb@mx.google.com> Date: Tue, 25 Aug 2015 06:12:21 -0700 (PDT) From: Yasuaki Ishimatsu To: Changsheng Liu Cc: , , , , , , , Changsheng Liu Subject: Re: [PATCH V2] mm:memory hot-add: memory can not been added to movable zone In-Reply-To: <1440055685-6083-1-git-send-email-liuchangsheng@inspur.com> References: <1440055685-6083-1-git-send-email-liuchangsheng@inspur.com> X-Mailer: Sylpheed 3.4.3 (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 Thu, 20 Aug 2015 03:28:05 -0400 Changsheng Liu wrote: > From: Changsheng Liu > > When memory is hot added, should_add_memory_movable() always returns 0 > because the movable zone is empty, so the memory that was hot added will > add to the normal zone even if we want to remove the memory. > > So we change should_add_memory_movable(): if the user config > CONFIG_MOVABLE_NODE it will return 1 when the movable zone is empty. > > Reviewed-by: Andrew Morton > Signed-off-by: Changsheng Liu > Tested-by: Dongdong Fan > --- > mm/memory_hotplug.c | 3 +-- > 1 files changed, 1 insertions(+), 2 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 26fbba7..ff658f2 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1199,8 +1199,7 @@ static int should_add_memory_movable(int nid, u64 start, u64 size) > struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE; > > if (zone_is_empty(movable_zone)) > - return 0; > - > + return IS_ENABLED(CONFIG_MOVABLE_NODE); > if (movable_zone->zone_start_pfn <= start_pfn) > return 1; Currently, kernel allows to create ZONE_MOVABLE after ZONE_NORMAL as follows: PFN low high ---|-------------|-------------|--- ZONE_NORMAL ZONE_MOVABLE But kernel does not allow to create ZONE_MOVABLE before ZONE_NORMAL as follows: PFN low high ---|-------------|-------------|--- ZONE_MOVABLE ZONE_NORMAL Also, kernel does not allow to create ZONE_MOVABLE in ZOME_NORMAL as follows: PFN low high ---|-------------|-------------|-------------|--- ZONE_NORMAL ZONE_MOVABLE ZONE_NORMAL So should_add_memory_movable() checks them. Accoring to your patch, when movable_zone is empty, the hot added memory is always managed to ZONE_MOVABLE. It means that ZONE_MOVALBE will puts before/in ZONE_NORMAL. You must prevent from creating ZONE_MOVABLE before/in ZONE_NORMAL. Thanks, Yasuaki Ishimatsu > > -- > 1.7.1 > > -- > 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