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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 187B0C4361B for ; Tue, 15 Dec 2020 22:21:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E123622D0A for ; Tue, 15 Dec 2020 22:21:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729771AbgLOWVE (ORCPT ); Tue, 15 Dec 2020 17:21:04 -0500 Received: from mail.kernel.org ([198.145.29.99]:44620 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728387AbgLOWVC (ORCPT ); Tue, 15 Dec 2020 17:21:02 -0500 Date: Tue, 15 Dec 2020 14:20:20 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1608070822; bh=3U6xznw5k4S17kSCr9BgUv6ipQkATNVw1nVtIV16FHM=; h=From:To:Subject:In-Reply-To:From; b=Hbm/LH7oMx5vwBYPNxqqkf2GcX0cr3tulPoReQulpWbSNAyRq+INvXKDzOYDg2SLw W/d0cwXp0/EMD8D2ojG5CMWyXbFh9g0NQ+Ps1BexQ/VghvLjMhhQl/jDlf1zemcCmq +bc330AFDFr6npq0b9gy5Lqbve1GM3Tp6A1sN2wo= From: Andrew Morton To: aarcange@redhat.com, akpm@linux-foundation.org, alex.shi@linux.alibaba.com, alexander.duyck@gmail.com, aryabinin@virtuozzo.com, daniel.m.jordan@oracle.com, hannes@cmpxchg.org, hughd@google.com, iamjoonsoo.kim@lge.com, jannh@google.com, khlebnikov@yandex-team.ru, kirill.shutemov@linux.intel.com, kirill@shutemov.name, linux-mm@kvack.org, mgorman@techsingularity.net, mhocko@kernel.org, mhocko@suse.com, mika.penttila@nextfour.com, minchan@kernel.org, mm-commits@vger.kernel.org, richard.weiyang@gmail.com, rong.a.chen@intel.com, shakeelb@google.com, tglx@linutronix.de, tj@kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz, vdavydov.dev@gmail.com, willy@infradead.org, yang.shi@linux.alibaba.com, ying.huang@intel.com Subject: [patch 03/19] mm/thp: simplify lru_add_page_tail() Message-ID: <20201215222020.cv9xZtxbs%akpm@linux-foundation.org> In-Reply-To: <20201215123253.954eca9a5ef4c0d52fd381fa@linux-foundation.org> User-Agent: s-nail v14.8.16 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org =46rom: Alex Shi Subject: mm/thp: simplify lru_add_page_tail() 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] Link: https://lkml.kernel.org/r/1604566549-62481-4-git-send-email-alex.shi@= linux.alibaba.com Signed-off-by: Alex Shi Reviewed-by: Kirill A. Shutemov Acked-by: Hugh Dickins Cc: Johannes Weiner Cc: Matthew Wilcox Cc: Mika Penttil=C3=A4 Cc: Alexander Duyck Cc: Andrea Arcangeli Cc: Andrey Ryabinin Cc: "Chen, Rong A" Cc: Daniel Jordan Cc: "Huang, Ying" Cc: Jann Horn Cc: Joonsoo Kim Cc: Kirill A. Shutemov Cc: Konstantin Khlebnikov Cc: Mel Gorman Cc: Michal Hocko Cc: Michal Hocko Cc: Minchan Kim Cc: Shakeel Butt Cc: Tejun Heo Cc: Thomas Gleixner Cc: Vladimir Davydov Cc: Vlastimil Babka Cc: Wei Yang Cc: Yang Shi Signed-off-by: Andrew Morton --- mm/huge_memory.c | 20 ++++++-------------- 1 file changed, 6 insertions(+), 14 deletions(-) --- a/mm/huge_memory.c~mm-thp-simplify-lru_add_page_tail +++ a/mm/huge_memory.c @@ -2367,24 +2367,16 @@ static void lru_add_page_tail(struct pag VM_BUG_ON_PAGE(PageLRU(tail), head); lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock); =20 - 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); } } =20 _