From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f176.google.com (mail-qk0-f176.google.com [209.85.220.176]) by kanga.kvack.org (Postfix) with ESMTP id 0CEAD6B0253 for ; Tue, 25 Aug 2015 09:12:23 -0400 (EDT) Received: by qkda128 with SMTP id a128so50050367qkd.3 for ; Tue, 25 Aug 2015 06:12:22 -0700 (PDT) Received: from mail-qg0-x22d.google.com (mail-qg0-x22d.google.com. [2607:f8b0:400d:c04::22d]) by mx.google.com with ESMTPS id n63si18774233qkh.4.2015.08.25.06.12.22 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 25 Aug 2015 06:12:22 -0700 (PDT) Received: by qgeg42 with SMTP id g42so106166490qge.1 for ; Tue, 25 Aug 2015 06:12:22 -0700 (PDT) Message-ID: <55dc69b5.46268c0a.faa78.24eb@mx.google.com> Date: Tue, 25 Aug 2015 06:12:21 -0700 (PDT) From: Yasuaki Ishimatsu 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> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Changsheng Liu Cc: akpm@linux-foundation.org, isimatu.yasuaki@jp.fujitsu.com, vbabka@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org, yanxiaofeng@inspur.com, fandd@inspur.com, Changsheng Liu 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 -- 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