From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 608F5C433DF for ; Fri, 17 Jul 2020 08:15:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4846420737 for ; Fri, 17 Jul 2020 08:15:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728274AbgGQIPG (ORCPT ); Fri, 17 Jul 2020 04:15:06 -0400 Received: from mx2.suse.de ([195.135.220.15]:54316 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726201AbgGQIPG (ORCPT ); Fri, 17 Jul 2020 04:15:06 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id A7952AFF7; Fri, 17 Jul 2020 08:15:08 +0000 (UTC) Subject: Re: [PATCH 1/4] mm/page_alloc: fix non cma alloc context From: Vlastimil Babka To: Joonsoo Kim Cc: Andrew Morton , Linux Memory Management List , LKML , kernel-team@lge.com, Christoph Hellwig , Roman Gushchin , Mike Kravetz , Naoya Horiguchi , Michal Hocko , "Aneesh Kumar K . V" , Joonsoo Kim , stable@vger.kernel.org References: <1594789529-6206-1-git-send-email-iamjoonsoo.kim@lge.com> <332d620b-bfe3-3b69-931b-77e3a74edbfd@suse.cz> <6f18d999-4518-31ce-4cea-9b5b89a577ad@suse.cz> <5a8b13d5-da40-7b1b-2968-e6701001cc0e@suse.cz> Message-ID: Date: Fri, 17 Jul 2020 10:15:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <5a8b13d5-da40-7b1b-2968-e6701001cc0e@suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/17/20 10:10 AM, Vlastimil Babka wrote: > On 7/17/20 9:29 AM, Joonsoo Kim wrote: >> 2020년 7월 16일 (목) 오후 4:45, Vlastimil Babka 님이 작성: >>> >>> On 7/16/20 9:27 AM, Joonsoo Kim wrote: >>> > 2020년 7월 15일 (수) 오후 5:24, Vlastimil Babka 님이 작성: >>> >> > /* >>> >> > * get_page_from_freelist goes through the zonelist trying to allocate >>> >> > * a page. >>> >> > @@ -3706,6 +3714,8 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, >>> >> > struct pglist_data *last_pgdat_dirty_limit = NULL; >>> >> > bool no_fallback; >>> >> > >>> >> > + current_alloc_flags(gfp_mask, &alloc_flags); >>> >> >>> >> I don't see why to move the test here? It will still be executed in the >>> >> fastpath, if that's what you wanted to avoid. >>> > >>> > I want to execute it on the fastpath, too. Reason that I moved it here >>> > is that alloc_flags could be reset on slowpath. See the code where >>> > __gfp_pfmemalloc_flags() is on. This is the only place that I can apply >>> > this option to all the allocation paths at once. >>> >>> But get_page_from_freelist() might be called multiple times in the slowpath, and >>> also anyone looking for gfp and alloc flags setup will likely not examine this >>> function. I don't see a problem in having it in two places that already deal >>> with alloc_flags setup, as it is now. >> >> I agree that anyone looking alloc flags will miss that function easily. Okay. >> I will place it on its original place, although we now need to add one >> more place. >> *Three places* are gfp_to_alloc_flags(), prepare_alloc_pages() and >> __gfp_pfmemalloc_flags(). > > Hm the check below should also work for ALLOC_OOM|ALLOC_NOCMA then. > > /* Avoid allocations with no watermarks from looping endlessly */ > if (tsk_is_oom_victim(current) && > (alloc_flags == ALLOC_OOM || > (gfp_mask & __GFP_NOMEMALLOC))) > goto nopage; > > Maybe it's simpler to change get_page_from_freelist() then. But document well. But then we have e.g. should_reclaim_retry() which calls __zone_watermark_ok() where ALLOC_CMA plays a role too, so that means we should have alloc_mask set up correctly wrt ALLOC_CMA at the __alloc_pages_slowpath() level... >> Thanks. >> >