From patchwork Thu Sep 24 03:28:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Alex Shi X-Patchwork-Id: 11795979 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8544E1668 for ; Thu, 24 Sep 2020 03:28:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 457AD238A1 for ; Thu, 24 Sep 2020 03:28:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 457AD238A1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 672F38E0003; Wed, 23 Sep 2020 23:28:46 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 4A3978E0005; 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Thu, 24 Sep 2020 03:28:43 +0000 (UTC) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R201e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04394;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=23;SR=0;TI=SMTPD_---0U9w0Ss1_1600918116; Received: from aliy80.localdomain(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0U9w0Ss1_1600918116) by smtp.aliyun-inc.com(127.0.0.1); Thu, 24 Sep 2020 11:28:39 +0800 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, aaron.lwe@gmail.com Cc: =?utf-8?q?Mika_Penttil=C3=A4?= Subject: [PATCH v19 05/20] mm/thp: Simplify lru_add_page_tail() Date: Thu, 24 Sep 2020 11:28:20 +0800 Message-Id: <1600918115-22007-6-git-send-email-alex.shi@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1600918115-22007-1-git-send-email-alex.shi@linux.alibaba.com> References: <1600918115-22007-1-git-send-email-alex.shi@linux.alibaba.com> MIME-Version: 1.0 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: 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 | 21 ++++++--------------- 1 file changed, 6 insertions(+), 15 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index fa0753229b52..8b92cd197218 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2326,25 +2326,16 @@ static void lru_add_page_tail(struct page *head, struct page *page_tail, VM_BUG_ON_PAGE(PageLRU(page_tail), head); lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock); - if (!list) - SetPageLRU(page_tail); - - if (likely(PageLRU(head))) - list_add_tail(&page_tail->lru, &head->lru); - else if (list) { + if (list) { /* page reclaim is reclaiming a huge page */ + VM_WARN_ON(PageLRU(head)); get_page(page_tail); list_add_tail(&page_tail->lru, list); } else { - /* - * Head page has not yet been counted, as an hpage, - * so we must account for each subpage individually. - * - * Put page_tail on the list at the correct position - * so they all end up in order. - */ - add_page_to_lru_list_tail(page_tail, lruvec, - page_lru(page_tail)); + /* head is still on lru (and we have it frozen) */ + VM_WARN_ON(!PageLRU(head)); + SetPageLRU(page_tail); + list_add_tail(&page_tail->lru, &head->lru); } }