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=-13.5 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,USER_AGENT_SANE_1 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 520D8C433DF for ; Wed, 26 Aug 2020 05:54:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1509C206FA for ; Wed, 26 Aug 2020 05:54:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1509C206FA 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 6EE796B0003; Wed, 26 Aug 2020 01:54:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6C57F6B0005; Wed, 26 Aug 2020 01:54:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5DBE86B0006; Wed, 26 Aug 2020 01:54:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0195.hostedemail.com [216.40.44.195]) by kanga.kvack.org (Postfix) with ESMTP id 4838E6B0003 for ; Wed, 26 Aug 2020 01:54:03 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 067A08248047 for ; Wed, 26 Aug 2020 05:54:03 +0000 (UTC) X-FDA: 77191653966.23.earth56_3f1594c27062 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin23.hostedemail.com (Postfix) with ESMTP id CEDE537604 for ; Wed, 26 Aug 2020 05:54:02 +0000 (UTC) X-HE-Tag: earth56_3f1594c27062 X-Filterd-Recvd-Size: 6002 Received: from out30-43.freemail.mail.aliyun.com (out30-43.freemail.mail.aliyun.com [115.124.30.43]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Wed, 26 Aug 2020 05:54:00 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01353;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=23;SR=0;TI=SMTPD_---0U6tzIW8_1598421228; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0U6tzIW8_1598421228) by smtp.aliyun-inc.com(127.0.0.1); Wed, 26 Aug 2020 13:53:49 +0800 Subject: Re: [PATCH v18 25/32] mm/mlock: remove lru_lock on TestClearPageMlocked in munlock_vma_page 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: "Kirill A. Shutemov" , Vlastimil Babka References: <1598273705-69124-1-git-send-email-alex.shi@linux.alibaba.com> <1598273705-69124-26-git-send-email-alex.shi@linux.alibaba.com> Message-ID: Date: Wed, 26 Aug 2020 13:52:18 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <1598273705-69124-26-git-send-email-alex.shi@linux.alibaba.com> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: CEDE537604 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 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: LKP reported a preemptiable issue on this patch. update and refresh the commit log. >From f18e8c87a045bbb8040006b6816ded1f55fa6f9c Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Sat, 25 Jul 2020 22:31:03 +0800 Subject: [PATCH] mm/mlock: remove lru_lock on TestClearPageMlocked in munlock_vma_page In the func munlock_vma_page, comments mentained lru_lock needed for serialization with split_huge_pages. But the page must be PageLocked as well as pages in split_huge_page series funcs. Thus the PageLocked is enough to serialize both funcs. So we could relief the TestClearPageMlocked/hpage_nr_pages which are not necessary under lru lock. As to another munlock func __munlock_pagevec, which no PageLocked protection and should remain lru protecting. LKP found a preempt issue on __mod_zone_page_state which need change to mod_zone_page_state. Thanks! Reported-by: kernel test robot Signed-off-by: Alex Shi Cc: Kirill A. Shutemov Cc: Vlastimil Babka Cc: Andrew Morton Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/mlock.c | 43 ++++++++++++++++--------------------------- 1 file changed, 16 insertions(+), 27 deletions(-) diff --git a/mm/mlock.c b/mm/mlock.c index 0448409184e3..cd88b93b0f0d 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -69,9 +69,9 @@ void clear_page_mlock(struct page *page) * * See __pagevec_lru_add_fn for more explanation. */ - if (!isolate_lru_page(page)) { + if (!isolate_lru_page(page)) putback_lru_page(page); - } else { + else { /* * We lost the race. the page already moved to evictable list. */ @@ -178,7 +178,6 @@ static void __munlock_isolation_failed(struct page *page) unsigned int munlock_vma_page(struct page *page) { int nr_pages; - struct lruvec *lruvec; /* For try_to_munlock() and to serialize with page migration */ BUG_ON(!PageLocked(page)); @@ -186,37 +185,22 @@ unsigned int munlock_vma_page(struct page *page) VM_BUG_ON_PAGE(PageTail(page), page); /* - * Serialize split tail pages in __split_huge_page_tail() which - * might otherwise copy PageMlocked to part of the tail pages before - * we clear it in the head page. It also stabilizes thp_nr_pages(). - * TestClearPageLRU can't be used here to block page isolation, since - * out of lock clear_page_mlock may interfer PageLRU/PageMlocked - * sequence, same as __pagevec_lru_add_fn, and lead the page place to - * wrong lru list here. So relay on PageLocked to stop lruvec change - * in mem_cgroup_move_account(). + * Serialize split tail pages in __split_huge_page_tail() by + * lock_page(); Do TestClearPageMlocked/PageLRU sequence like + * clear_page_mlock(). */ - lruvec = lock_page_lruvec_irq(page); - - if (!TestClearPageMlocked(page)) { + if (!TestClearPageMlocked(page)) /* Potentially, PTE-mapped THP: do not skip the rest PTEs */ - nr_pages = 1; - goto unlock_out; - } + return 0; nr_pages = thp_nr_pages(page); - __mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); + mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); - if (__munlock_isolate_lru_page(page, lruvec, true)) { - unlock_page_lruvec_irq(lruvec); + if (!isolate_lru_page(page)) __munlock_isolated_page(page); - goto out; - } - __munlock_isolation_failed(page); - -unlock_out: - unlock_page_lruvec_irq(lruvec); + else + __munlock_isolation_failed(page); -out: return nr_pages - 1; } @@ -305,6 +289,11 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone) /* block memcg change in mem_cgroup_move_account */ lock_page_memcg(page); + /* + * Serialize split tail pages in __split_huge_page_tail() which + * might otherwise copy PageMlocked to part of the tail pages + * before we clear it in the head page. + */ lruvec = relock_page_lruvec_irq(page, lruvec); if (TestClearPageMlocked(page)) { /* -- 2.17.1