Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751187AbdH1GpM (ORCPT ); Mon, 28 Aug 2017 02:45:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:55541 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750767AbdH1GpK (ORCPT ); Mon, 28 Aug 2017 02:45:10 -0400 Subject: Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for ZONE_MOVABLE request To: Joonsoo Kim Cc: Andrew Morton , Michal Hocko , Mel Gorman , Johannes Weiner , "Aneesh Kumar K . V" , Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Linux API References: <1503553546-27450-1-git-send-email-iamjoonsoo.kim@lge.com> <20170825002031.GD29701@js1304-P5Q-DELUXE> <20170828002857.GB9167@js1304-P5Q-DELUXE> From: Vlastimil Babka Message-ID: <78dd0160-14e8-22a6-bd10-d37bbd39f77b@suse.cz> Date: Mon, 28 Aug 2017 08:45:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20170828002857.GB9167@js1304-P5Q-DELUXE> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1742 Lines: 47 +CC linux-api On 08/28/2017 02:28 AM, Joonsoo Kim wrote: > On Fri, Aug 25, 2017 at 09:56:10AM +0200, Vlastimil Babka wrote: >> On 08/25/2017 02:20 AM, Joonsoo Kim wrote: >>> On Thu, Aug 24, 2017 at 11:41:58AM +0200, Vlastimil Babka wrote: >>> >>> Hmm, this is already pointed by Minchan and I have answered that. >>> >>> lkml.kernel.org/r/<20170421013243.GA13966@js1304-desktop> >>> >>> If you have a better idea, please let me know. >> >> My idea is that size of sysctl_lowmem_reserve_ratio is ZONE_NORMAL+1 and >> it has no entries for zones > NORMAL. The >> setup_per_zone_lowmem_reserve() is adjusted to only set >> lower_zone->lowmem_reserve[j] for idx <= ZONE_NORMAL. >> >> I can't imagine somebody would want override the ratio for HIGHMEM or >> MOVABLE >> (where it has no effect anyway) so the simplest thing is not to expose >> it at all. > > Seems reasonable. However, if there is a user who checks > sysctl_lowmem_reserve_ratio entry for HIGHMEM and change it, suggested > interface will cause a problem since it doesn't expose ratio for > HIGHMEM. Am I missing something? As you explained, it makes little sense to change it for HIGHMEM which only affects MOVABLE allocations. Also I doubt there are many systems with both HIGHMEM (implies 32bit) *and* MOVABLE (implies NUMA, memory hotplug...) zones. So I would just remove it, and if somebody will really miss it, we can always add it back. In any case, please CC linux-api on the next version. > Thanks. > > >> >>> Thanks. >>> >> >> -- >> 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