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=-11.3 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,URIBL_BLOCKED,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 262EFC55ABD for ; Wed, 11 Nov 2020 13:04:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8092C20809 for ; Wed, 11 Nov 2020 13:04:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8092C20809 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 520BF6B0068; Wed, 11 Nov 2020 08:04:01 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4A90C6B006E; Wed, 11 Nov 2020 08:04:01 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 34A776B0070; Wed, 11 Nov 2020 08:04:01 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0121.hostedemail.com [216.40.44.121]) by kanga.kvack.org (Postfix) with ESMTP id 040E06B0068 for ; Wed, 11 Nov 2020 08:04:00 -0500 (EST) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 83CAF181AC9CC for ; Wed, 11 Nov 2020 13:04:00 +0000 (UTC) X-FDA: 77472155040.26.shirt90_5b07436272fd Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin26.hostedemail.com (Postfix) with ESMTP id 542881804B661 for ; Wed, 11 Nov 2020 13:04:00 +0000 (UTC) X-HE-Tag: shirt90_5b07436272fd X-Filterd-Recvd-Size: 4454 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf15.hostedemail.com (Postfix) with ESMTP for ; Wed, 11 Nov 2020 13:03:59 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4860BABD6; Wed, 11 Nov 2020 13:03:58 +0000 (UTC) Subject: Re: [PATCH v21 12/19] mm/mlock: remove lru_lock on TestClearPageMlocked To: Alex Shi , 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" References: <1604566549-62481-1-git-send-email-alex.shi@linux.alibaba.com> <1604566549-62481-13-git-send-email-alex.shi@linux.alibaba.com> From: Vlastimil Babka Message-ID: <0df624ca-a0d2-6a9f-f114-04f91bf35415@suse.cz> Date: Wed, 11 Nov 2020 14:03:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <1604566549-62481-13-git-send-email-alex.shi@linux.alibaba.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit 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: On 11/5/20 9:55 AM, Alex Shi wrote: > 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. > > Further more, Hugh Dickins pointed: before splitting in > split_huge_page_to_list, the page was unmap_page() to remove pmd/ptes > which protect the page from munlock. Thus, no needs to guard > __split_huge_page_tail for mlock clean, just keep the lru_lock there for > isolation purpose. > > LKP found a preempt issue on __mod_zone_page_state which need change > to mod_zone_page_state. Thanks! > > Signed-off-by: Alex Shi > Acked-by: Hugh Dickins > Acked-by: Johannes Weiner > Cc: Kirill A. Shutemov > Cc: Vlastimil Babka > Cc: Andrew Morton > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org Acked-by: Vlastimil Babka Nit below: > --- > mm/mlock.c | 26 +++++--------------------- > 1 file changed, 5 insertions(+), 21 deletions(-) > > diff --git a/mm/mlock.c b/mm/mlock.c > index 884b1216da6a..796c726a0407 100644 > --- a/mm/mlock.c > +++ b/mm/mlock.c > @@ -187,40 +187,24 @@ static void __munlock_isolation_failed(struct page *page) > unsigned int munlock_vma_page(struct page *page) > { > int nr_pages; > - pg_data_t *pgdat = page_pgdat(page); > > /* For try_to_munlock() and to serialize with page migration */ Now the reasons for locking are expanded? > BUG_ON(!PageLocked(page)); > - > VM_BUG_ON_PAGE(PageTail(page), page); > > - /* > - * Serialize with any parallel __split_huge_page_refcount() 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(). > - */ > - spin_lock_irq(&pgdat->lru_lock); > - > 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, true)) { > - spin_unlock_irq(&pgdat->lru_lock); > + if (!isolate_lru_page(page)) > __munlock_isolated_page(page); > - goto out; > - } > - __munlock_isolation_failed(page); > - > -unlock_out: > - spin_unlock_irq(&pgdat->lru_lock); > + else > + __munlock_isolation_failed(page); > > -out: > return nr_pages - 1; > } > >