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=-2.5 required=3.0 tests=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 2B7F5C3A5A9 for ; Wed, 4 Sep 2019 08:19:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id ECB8D2339D for ; Wed, 4 Sep 2019 08:19:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ECB8D2339D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6D2816B0003; Wed, 4 Sep 2019 04:19:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 65C0F6B0006; Wed, 4 Sep 2019 04:19:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 522616B0007; Wed, 4 Sep 2019 04:19:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0220.hostedemail.com [216.40.44.220]) by kanga.kvack.org (Postfix) with ESMTP id 2BF556B0003 for ; Wed, 4 Sep 2019 04:19:23 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id B7DEC82437C9 for ; Wed, 4 Sep 2019 08:19:22 +0000 (UTC) X-FDA: 75896538564.11.nest63_179be1097532e X-HE-Tag: nest63_179be1097532e X-Filterd-Recvd-Size: 4444 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Wed, 4 Sep 2019 08:19:22 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 7F15BADD9; Wed, 4 Sep 2019 08:19:20 +0000 (UTC) Date: Wed, 4 Sep 2019 10:19:15 +0200 From: Michal Hocko To: Park Sangwoo 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: Re: Re: Re: Re: [PATCH] mm: Add nr_free_highatomimic to fix incorrect watermatk routine Message-ID: <20190904081915.GH3838@dhcp22.suse.cz> References: <20190904065457.GA19826@LGEARND18B2> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190904065457.GA19826@LGEARND18B2> User-Agent: Mutt/1.10.1 (2018-07-13) Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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=EF=BF=BD wrote: > > >>> On Fri 30-08-19 18:25:53, Sangwoo wrote: > > >>>> The highatomic migrate block can be increased to 1% of Total mem= ory. > > >>>> And, this is for only highorder ( > 0 order). So, this block siz= e is > > >>>> excepted during check watermark if allocation type isn't alloc_h= arder. > > >>>> > > >>>> 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 min= us 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:0x14200c= a > > >>> (GFP_HIGHUSER_MOVABLE), nodemask=3D(null) > > >>>>> Binder:6218_2 cpuset=3Dbackground mems_allowed=3D0 > > >>>> > > >>>> How come this order-0 sleepable allocation fails? The upstream k= ernel > > >>>> doesn't fail those allocations unless the process context is kil= led by > > >>>> the oom killer. > > >>>=20 > > >>> 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 specifi= c > > >> issue? > > > > > > There is the other case of fail order-0 fail. > > > ---- > > > hvdcp_opti: page allocation failure: order:0, mode:0x1004000(GFP_NO= WAIT|__GFP_COMP), nodemask=3D(null) > >=20 > > 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 primar= y > > purpose of the reservation.=20 >=20 > 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 doe= s not occur for previously shared cases. >=20 > In __zone_water_mark_ok(...) func, if it is not atomic allocation, high= atomic size is excluded. >=20 > bool __zone_watermark_ok(struct zone *z, > ... > { > ... > if (likely(!alloc_harder)) { > free_pages -=3D z->nr_reserved_highatomic; > ... > } >=20 > 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? I am sorry but I find your reasoning really hard to follow. --=20 Michal Hocko SUSE Labs