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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY autolearn=ham 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 E49E0C31E46 for ; Wed, 12 Jun 2019 17:14:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C4BE1215EA for ; Wed, 12 Jun 2019 17:14:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728987AbfFLROC (ORCPT ); Wed, 12 Jun 2019 13:14:02 -0400 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:42790 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726721AbfFLROB (ORCPT ); Wed, 12 Jun 2019 13:14:01 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R281e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07487;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0TU.ZihY_1560359634; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TU.ZihY_1560359634) by smtp.aliyun-inc.com(127.0.0.1); Thu, 13 Jun 2019 01:13:57 +0800 Subject: Re: [PATCH 2/4] mm: thp: make deferred split shrinker memcg aware To: "Kirill A. Shutemov" Cc: ktkhai@virtuozzo.com, kirill.shutemov@linux.intel.com, hannes@cmpxchg.org, mhocko@suse.com, hughd@google.com, shakeelb@google.com, rientjes@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1559887659-23121-1-git-send-email-yang.shi@linux.alibaba.com> <1559887659-23121-3-git-send-email-yang.shi@linux.alibaba.com> <20190612024747.f5nsol7ntvubjckq@box> <20190612100906.xllp2bfgmadvbh2q@box> From: Yang Shi Message-ID: Date: Wed, 12 Jun 2019 10:13:51 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20190612100906.xllp2bfgmadvbh2q@box> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/12/19 3:09 AM, Kirill A. Shutemov wrote: > On Tue, Jun 11, 2019 at 10:06:36PM -0700, Yang Shi wrote: >> >> On 6/11/19 7:47 PM, Kirill A. Shutemov wrote: >>> On Fri, Jun 07, 2019 at 02:07:37PM +0800, Yang Shi wrote: >>>> + /* >>>> + * The THP may be not on LRU at this point, e.g. the old page of >>>> + * NUMA migration. And PageTransHuge is not enough to distinguish >>>> + * with other compound page, e.g. skb, THP destructor is not used >>>> + * anymore and will be removed, so the compound order sounds like >>>> + * the only choice here. >>>> + */ >>>> + if (PageTransHuge(page) && compound_order(page) == HPAGE_PMD_ORDER) { >>> What happens if the page is the same order as THP is not THP? Why removing >> It may corrupt the deferred split queue since it is never added into the >> list, but deleted here. >> >>> of destructor is required? >> Due to the change to free_transhuge_page() (extracted deferred split queue >> manipulation and moved before memcg uncharge since page->mem_cgroup is >> needed), it just calls free_compound_page(). So, it sounds pointless to >> still keep THP specific destructor. >> >> It looks there is not a good way to tell if the compound page is THP in >> free_page path or not, we may keep the destructor just for this? > Other option would be to move mem_cgroup_uncharge(page); from > __page_cache_release() to destructors. Destructors will be able to > call it as it fits. Yes, it is an option. Since __page_cache_release() is called by __put_single_page() too, so mem_cgroup_uncharge() has to be called in both __put_single_page() and the desctructor (free_compound_page() which is called by both THP and other compound page except HugeTLB). But, it sounds acceptable IMHO. >