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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_SANE_1 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 AD99BC2D0A3 for ; Fri, 30 Oct 2020 02:50:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61DE5207DE for ; Fri, 30 Oct 2020 02:50:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726386AbgJ3Cuk (ORCPT ); Thu, 29 Oct 2020 22:50:40 -0400 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]:37169 "EHLO out30-57.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726365AbgJ3Cuh (ORCPT ); Thu, 29 Oct 2020 22:50:37 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=22;SR=0;TI=SMTPD_---0UDbYOcX_1604026231; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0UDbYOcX_1604026231) by smtp.aliyun-inc.com(127.0.0.1); Fri, 30 Oct 2020 10:50:32 +0800 Subject: Re: [PATCH v20 05/20] mm/thp: Simplify lru_add_page_tail() From: Alex Shi To: akpm@linux-foundation.org, mgorman@techsingularity.net, tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com, willy@infradead.org, hannes@cmpxchg.org, lkp@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, shakeelb@google.com, iamjoonsoo.kim@lge.com, richard.weiyang@gmail.com, kirill@shutemov.name, alexander.duyck@gmail.com, rong.a.chen@intel.com, mhocko@suse.com, vdavydov.dev@gmail.com, shy828301@gmail.com Cc: =?UTF-8?Q?Mika_Penttil=c3=a4?= References: <1603968305-8026-1-git-send-email-alex.shi@linux.alibaba.com> <1603968305-8026-6-git-send-email-alex.shi@linux.alibaba.com> Message-ID: <5675f78c-5bd2-c413-41b5-a354ca897fab@linux.alibaba.com> Date: Fri, 30 Oct 2020 10:48:25 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <1603968305-8026-6-git-send-email-alex.shi@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org patch changed since varible rename in 4th patch: >From 5014c78418284f70be232a37fa3a4660a54e83c0 Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Fri, 10 Jul 2020 12:53:22 +0800 Subject: [PATCH v21 05/20] mm/thp: Simplify lru_add_page_tail() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Simplify lru_add_page_tail(), there are actually only two cases possible: split_huge_page_to_list(), with list supplied and head isolated from lru by its caller; or split_huge_page(), with NULL list and head on lru - because when head is racily isolated from lru, the isolator's reference will stop the split from getting any further than its page_ref_freeze(). So decide between the two cases by "list", but add VM_WARN_ON()s to verify that they match our lru expectations. [Hugh Dickins: rewrite commit log] Signed-off-by: Alex Shi Reviewed-by: Kirill A. Shutemov Acked-by: Hugh Dickins Cc: Kirill A. Shutemov Cc: Andrew Morton Cc: Johannes Weiner Cc: Matthew Wilcox Cc: Hugh Dickins Cc: Mika Penttilä Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/huge_memory.c | 20 ++++++-------------- 1 file changed, 6 insertions(+), 14 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 32a4bf5b80c8..cedcdbeb98b4 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2354,24 +2354,16 @@ static void lru_add_page_tail(struct page *head, struct page *tail, VM_BUG_ON_PAGE(PageLRU(tail), head); lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock); - if (!list) - SetPageLRU(tail); - - if (likely(PageLRU(head))) - list_add_tail(&tail->lru, &head->lru); - else if (list) { + if (list) { /* page reclaim is reclaiming a huge page */ + VM_WARN_ON(PageLRU(head)); get_page(tail); list_add_tail(&tail->lru, list); } else { - /* - * Head page has not yet been counted, as an hpage, - * so we must account for each subpage individually. - * - * Put tail on the list at the correct position - * so they all end up in order. - */ - add_page_to_lru_list_tail(tail, lruvec, page_lru(tail)); + /* head is still on lru (and we have it frozen) */ + VM_WARN_ON(!PageLRU(head)); + SetPageLRU(tail); + list_add_tail(&tail->lru, &head->lru); } } -- 1.8.3.1