Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751286AbdH2HAX (ORCPT ); Tue, 29 Aug 2017 03:00:23 -0400 Received: from mx2.suse.de ([195.135.220.15]:41140 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751218AbdH2HAU (ORCPT ); Tue, 29 Aug 2017 03:00:20 -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> <78dd0160-14e8-22a6-bd10-d37bbd39f77b@suse.cz> <20170829003657.GC14489@js1304-P5Q-DELUXE> From: Vlastimil Babka Message-ID: Date: Tue, 29 Aug 2017 09:00:16 +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: <20170829003657.GC14489@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: 1372 Lines: 32 On 08/29/2017 02:36 AM, Joonsoo Kim wrote: > On Mon, Aug 28, 2017 at 08:45:07AM +0200, Vlastimil Babka wrote: >> +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: >>> >>> 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. > > If we will accept a change that potentially breaks the user, I think > that making zero as a special value for sysctl_lowmem_reserve_ratio > is better solution. How about this way? I'd prefer removal, but won't object to zero. Certainly much better than UINT_MAX. > Thanks. > -- > To unsubscribe from this list: send the line "unsubscribe linux-api" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >