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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 47D94C2D0C4 for ; Wed, 11 Dec 2019 03:52:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 28BB2206EC for ; Wed, 11 Dec 2019 03:52:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727349AbfLKDwp (ORCPT ); Tue, 10 Dec 2019 22:52:45 -0500 Received: from out30-54.freemail.mail.aliyun.com ([115.124.30.54]:54312 "EHLO out30-54.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726642AbfLKDwo (ORCPT ); Tue, 10 Dec 2019 22:52:44 -0500 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=e01e07486;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=38;SR=0;TI=SMTPD_---0TkapNAY_1576036356; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0TkapNAY_1576036356) by smtp.aliyun-inc.com(127.0.0.1); Wed, 11 Dec 2019 11:52:37 +0800 Subject: Re: [PATCH v5 2/8] mm/lru: replace pgdat lru_lock with lruvec lock To: Matthew Wilcox Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mgorman@techsingularity.net, tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com, yang.shi@linux.alibaba.com, shakeelb@google.com, hannes@cmpxchg.org, Michal Hocko , Vladimir Davydov , Roman Gushchin , Chris Down , Thomas Gleixner , Vlastimil Babka , Qian Cai , Andrey Ryabinin , "Kirill A. Shutemov" , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Andrea Arcangeli , David Rientjes , "Aneesh Kumar K.V" , swkhack , "Potyra, Stefan" , Mike Rapoport , Stephen Rothwell , Colin Ian King , Jason Gunthorpe , Mauro Carvalho Chehab , Peng Fan , Nikolay Borisov , Ira Weiny , Kirill Tkhai , Yafang Shao References: <1575978384-222381-1-git-send-email-alex.shi@linux.alibaba.com> <1575978384-222381-3-git-send-email-alex.shi@linux.alibaba.com> <20191210134133.GI32169@bombadil.infradead.org> From: Alex Shi Message-ID: Date: Wed, 11 Dec 2019 11:51:47 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 In-Reply-To: <20191210134133.GI32169@bombadil.infradead.org> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 2019/12/10 ÏÂÎç9:41, Matthew Wilcox дµÀ: > On Tue, Dec 10, 2019 at 07:46:18PM +0800, Alex Shi wrote: >> -static void lock_page_lru(struct page *page, int *isolated) >> +static struct lruvec *lock_page_lru(struct page *page, int *isolated) >> { >> - pg_data_t *pgdat = page_pgdat(page); >> + struct lruvec *lruvec = lock_page_lruvec_irq(page); >> >> - spin_lock_irq(&pgdat->lru_lock); >> if (PageLRU(page)) { >> - struct lruvec *lruvec; >> >> - lruvec = mem_cgroup_page_lruvec(page, pgdat); >> ClearPageLRU(page); >> del_page_from_lru_list(page, lruvec, page_lru(page)); >> *isolated = 1; >> } else >> *isolated = 0; >> + >> + return lruvec; >> } > > I still don't understand how this is supposed to work for !PageLRU > pages. Which lruvec have you locked if this page isn't on an LRU? > Good question. We could just fold it under PageLRU and no meaning changes. Is this better to has this patch? Thanks Alex commit 0f4b66d4a42397d57638352b738c3f9658003e44 Author: Alex Shi Date: Wed Dec 11 11:31:53 2019 +0800 mm/memcg: fold lock in lock_page_lru According to the calling path of commit_charge, the lrucare is bound with PageLRU, so we could just fold it under PageLRU. This has no functional change. Signed-off-by: Alex Shi Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Andrew Morton Cc: cgroups@vger.kernel.org Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 833df0ce1bc1..4fe2252cf437 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2622,9 +2622,10 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages) static struct lruvec *lock_page_lru(struct page *page, int *isolated) { - struct lruvec *lruvec = lock_page_lruvec_irq(page); + struct lruvec *lruvec = NULL; if (PageLRU(page)) { + lruvec = lock_page_lruvec_irq(page); ClearPageLRU(page); del_page_from_lru_list(page, lruvec, page_lru(page)); @@ -2638,17 +2639,18 @@ static struct lruvec *lock_page_lru(struct page *page, int *isolated) static void unlock_page_lru(struct page *page, int isolated, struct lruvec *locked_lruvec) { - struct lruvec *lruvec; + if (isolated) { + struct lruvec *lruvec; - unlock_page_lruvec_irq(locked_lruvec); - lruvec = lock_page_lruvec_irq(page); + if (locked_lruvec) + unlock_page_lruvec_irq(locked_lruvec); + lruvec = lock_page_lruvec_irq(page); - if (isolated) { VM_BUG_ON_PAGE(PageLRU(page), page); SetPageLRU(page); add_page_to_lru_list(page, lruvec, page_lru(page)); + unlock_page_lruvec_irq(lruvec); } - unlock_page_lruvec_irq(lruvec); } static void commit_charge(struct page *page, struct mem_cgroup *memcg,