From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 9988B6B025F for ; Wed, 11 Oct 2017 04:13:21 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id m72so497509wmc.0 for ; Wed, 11 Oct 2017 01:13:21 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id m28si10175521wmc.149.2017.10.11.01.13.20 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 11 Oct 2017 01:13:20 -0700 (PDT) Date: Wed, 11 Oct 2017 10:13:17 +0200 From: Michal Hocko Subject: Re: [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early Message-ID: <20171011081317.b2cdnhjdyzgdo3up@dhcp22.suse.cz> References: <20170918070834.13083-1-mhocko@kernel.org> <20170918070834.13083-2-mhocko@kernel.org> <87bmlfw6mj.fsf@concordia.ellerman.id.au> <20171010122726.6jrfdzkscwge6gez@dhcp22.suse.cz> <87infmz9xd.fsf@concordia.ellerman.id.au> <20171011065123.e7jvoftmtso3vcha@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Michael Ellerman , Andrew Morton , KAMEZAWA Hiroyuki , Reza Arbab , Yasuaki Ishimatsu , qiuxishi@huawei.com, Igor Mammedov , Vitaly Kuznetsov , linux-mm@kvack.org, LKML On Wed 11-10-17 10:04:39, Vlastimil Babka wrote: > On 10/11/2017 08:51 AM, Michal Hocko wrote: [...] > > This is really strange! As you write in other email the page is > > reserved. That means that some of the earlier checks > > if (zone_idx(zone) == ZONE_MOVABLE) > > return false; > > mt = get_pageblock_migratetype(page); > > if (mt == MIGRATE_MOVABLE || is_migrate_cma(mt)) > > The MIGRATE_MOVABLE check is indeed bogus, because that doesn't > guarantee there are no unmovable pages in the block (CMA block OTOH > should be a guarantee). OK, thanks for confirmation. I will remove the MIGRATE_MOVABLE check here. Do you think it is worth removing CMA check as well? This is merely an optimization AFAIU because we do not have to check the full pageblockworth of pfns. Anyway, let's way for Michael to confirm it really helps. If yes I will post a full patch and ask Andrew to add it as a prerequisite for this patch when sending to Linus to prevent the regression. -- Michal Hocko SUSE Labs -- 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