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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E403CC43334 for ; Fri, 24 Jun 2022 09:22:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231685AbiFXJW3 (ORCPT ); Fri, 24 Jun 2022 05:22:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37582 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231628AbiFXJWZ (ORCPT ); Fri, 24 Jun 2022 05:22:25 -0400 Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2316C699AD for ; Fri, 24 Jun 2022 02:22:23 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R511e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0VHGdsVJ_1656062539; Received: from 30.97.49.29(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VHGdsVJ_1656062539) by smtp.aliyun-inc.com; Fri, 24 Jun 2022 17:22:20 +0800 Message-ID: <8e55a741-969b-d827-9af0-d793cbc6b2a9@linux.alibaba.com> Date: Fri, 24 Jun 2022 17:22:26 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH 2/7] migrate_pages(): remove unnecessary list_safe_reset_next() To: Huang Ying , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zi Yan , Yang Shi References: <20220624025309.1033400-1-ying.huang@intel.com> <20220624025309.1033400-3-ying.huang@intel.com> From: Baolin Wang In-Reply-To: <20220624025309.1033400-3-ying.huang@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/24/2022 10:53 AM, Huang Ying wrote: > Before commit b5bade978e9b ("mm: migrate: fix the return value of > migrate_pages()"), the tail pages of THP will be put in the "from" > list directly. So one of the loop cursors (page2) needs to be reset, > as is done in try_split_thp() via list_safe_reset_next(). But after > the commit, the tail pages of THP will be put in a dedicated > list (thp_split_pages). That is, the "from" list will not be changed > during splitting. So, it's unnecessary to call list_safe_reset_next() > anymore. > > This is a code cleanup, no functionality changes are expected. > > Signed-off-by: "Huang, Ying" > Cc: Baolin Wang > Cc: Zi Yan > Cc: Yang Shi > --- Looks good to me. Reviewed-by: Baolin Wang > mm/migrate.c | 13 +++++-------- > 1 file changed, 5 insertions(+), 8 deletions(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index a271554be7a1..82444e7df9f1 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1300,16 +1300,13 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, > return rc; > } > > -static inline int try_split_thp(struct page *page, struct page **page2, > - struct list_head *from) > +static inline int try_split_thp(struct page *page, struct list_head *split_pages) > { > - int rc = 0; > + int rc; > > lock_page(page); > - rc = split_huge_page_to_list(page, from); > + rc = split_huge_page_to_list(page, split_pages); > unlock_page(page); > - if (!rc) > - list_safe_reset_next(page, *page2, lru); > > return rc; > } > @@ -1413,7 +1410,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, > /* THP migration is unsupported */ > if (is_thp) { > nr_thp_failed++; > - if (!try_split_thp(page, &page2, &thp_split_pages)) { > + if (!try_split_thp(page, &thp_split_pages)) { > nr_thp_split++; > goto retry; > } > @@ -1432,7 +1429,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, > */ > if (is_thp && !nosplit) { > nr_thp_failed++; > - if (!try_split_thp(page, &page2, &thp_split_pages)) { > + if (!try_split_thp(page, &thp_split_pages)) { > nr_thp_split++; > goto retry; > }