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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 CF170C3A59E for ; Thu, 5 Sep 2019 01:46:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ADC3120882 for ; Thu, 5 Sep 2019 01:46:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730518AbfIEBq1 (ORCPT ); Wed, 4 Sep 2019 21:46:27 -0400 Received: from lgeamrelo11.lge.com ([156.147.23.51]:44377 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727544AbfIEBq1 (ORCPT ); Wed, 4 Sep 2019 21:46:27 -0400 Received: from unknown (HELO lgemrelse6q.lge.com) (156.147.1.121) by 156.147.23.51 with ESMTP; 5 Sep 2019 10:46:24 +0900 X-Original-SENDERIP: 156.147.1.121 X-Original-MAILFROM: sangwoo2.park@lge.com Received: from unknown (HELO LGEARND18B2) (10.168.178.132) by 156.147.1.121 with ESMTP; 5 Sep 2019 10:46:24 +0900 X-Original-SENDERIP: 10.168.178.132 X-Original-MAILFROM: sangwoo2.park@lge.com Date: Thu, 5 Sep 2019 10:46:24 +0900 From: Park Sangwoo To: mhocko@kernel.org Cc: hannes@cmpxchg.org, arunks@codeaurora.org, guro@fb.com, richard.weiyang@gmail.com, glider@google.com, jannh@google.com, dan.j.williams@intel.com, akpm@linux-foundation.org, alexander.h.duyck@linux.intel.com, rppt@linux.vnet.ibm.com, gregkh@linuxfoundation.org, janne.huttunen@nokia.com, pasha.tatashin@soleen.com, vbabka@suse.cz, osalvador@suse.de, mgorman@techsingularity.net, khlebnikov@yandex-team.ru, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm: Add nr_free_highatomimic to fix incorrect watermatk routine Message-ID: <20190905014624.GA25551@LGEARND18B2> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Wed 04-09-19 15:54:57, Park Sangwoo wrote: > > On Tue 03-09-19 18:59:59, Park Sangwoo wrote: > > > On Mon 02-09-19 13:34:54, Sangwoo� wrote: > > >>> On Fri 30-08-19 18:25:53, Sangwoo wrote: > > >>>> The highatomic migrate block can be increased to 1% of Total memory. > > >>>> And, this is for only highorder ( > 0 order). So, this block size is > > >>>> excepted during check watermark if allocation type isn't alloc_harder. > > >>>> > > >>>> It has problem. The usage of highatomic is already calculated at > > >>> NR_FREE_PAGES. > > >>>>> So, if we except total block size of highatomic, it's twice minus size of > > >>> allocated > > >>>>> highatomic. > > >>>>> It's cause allocation fail although free pages enough. > > >>>>> > > >>>>> We checked this by random test on my target(8GB RAM). > > >>>>> > > >>>>> Binder:6218_2: page allocation failure: order:0, mode:0x14200ca > > >>> (GFP_HIGHUSER_MOVABLE), nodemask=(null) > > >>>>> Binder:6218_2 cpuset=background mems_allowed=0 > > >>>> > > >>>> How come this order-0 sleepable allocation fails? The upstream kernel > > >>>> doesn't fail those allocations unless the process context is killed by > > >>>> the oom killer. > > >>> > > > >>> Most calltacks are zsmalloc, as shown below. > > > >> > > > >> What makes those allocations special so that they fail unlike any other > > > >> normal order-0 requests? Also do you see the same problem with the > > > >> current upstream kernel? Is it possible this is an Android specific > > > >> issue? > > > > > > > > There is the other case of fail order-0 fail. > > > > ---- > > > > hvdcp_opti: page allocation failure: order:0, mode:0x1004000(GFP_NOWAIT|__GFP_COMP), nodemask=(null) > > > > > > This is an atomic allocation and failing that one is not a problem > > > usually. High atomic reservations might prevent GFP_NOWAIT allocation > > > from suceeding but I do not see that as a problem. This is the primary > > > purpose of the reservation. > > > > Thanks, your answer helped me. However, my suggestion is not to modify the use and management of the high atomic region, > > but to calculate the exact free size of the highatomic so that fail does not occur for previously shared cases. > > > > In __zone_water_mark_ok(...) func, if it is not atomic allocation, high atomic size is excluded. > > > > bool __zone_watermark_ok(struct zone *z, > > ... > > { > > ... > > if (likely(!alloc_harder)) { > > free_pages -= z->nr_reserved_highatomic; > > ... > > } > > > > However, free_page excludes the size already allocated by hiahtomic. > > If highatomic block is small(Under 4GB RAM), it could be no problem. > > But, the larger the memory size, the greater the chance of problems. > > (Becasue highatomic size can be increased up to 1% of memory) > > I still do not understand. NR_FREE_PAGES should include the amount of > hhighatomic reserves, right. So reducing the free_pages for normal > allocations just makes sense. Or what do I miss? You are right. But z->nr_reserved_highatomic value is total size of highatomic migrate type per zone. nr_reserved_highatomic = (# of allocated of highatomic) + (# of free list of highatomic). And (# of allocated of hiagatomic) is already excluded at NR_FREE_PAGES. So, if reducing nr_reserved_highatomic at NR_FREE_PAGES, the (# of allocated of highatomic) is double reduced. So I proposal that only (# of free list of highatomic) is reduced at NR_FREE_PAGE. if (likely(!alloc_harder)) { - free_pages -= z->nr_reserved_highatomic; + free_pages -= zone_page_state(z, NR_FREE_HIGHATOMIC_PAGES); } else { > > I am sorry but I find your reasoning really hard to follow.