From patchwork Thu Dec 17 06:28:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alex Shi X-Patchwork-Id: 11979109 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_GIT 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 EA985C2BB48 for ; Thu, 17 Dec 2020 06:29:13 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7D8B520575 for ; Thu, 17 Dec 2020 06:29:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7D8B520575 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 E8CC46B0068; Thu, 17 Dec 2020 01:29:12 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id E63726B0071; Thu, 17 Dec 2020 01:29:12 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D50596B0072; Thu, 17 Dec 2020 01:29:12 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0106.hostedemail.com [216.40.44.106]) by kanga.kvack.org (Postfix) with ESMTP id BE3116B0068 for ; Thu, 17 Dec 2020 01:29:12 -0500 (EST) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 8000D180AD804 for ; Thu, 17 Dec 2020 06:29:12 +0000 (UTC) X-FDA: 77601796944.23.hope88_2607e5a27432 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin23.hostedemail.com (Postfix) with ESMTP id 6437F37604 for ; Thu, 17 Dec 2020 06:29:12 +0000 (UTC) X-HE-Tag: hope88_2607e5a27432 X-Filterd-Recvd-Size: 2708 Received: from out30-57.freemail.mail.aliyun.com (out30-57.freemail.mail.aliyun.com [115.124.30.57]) by imf36.hostedemail.com (Postfix) with ESMTP for ; Thu, 17 Dec 2020 06:29:07 +0000 (UTC) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R131e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0UItliQ7_1608186540; Received: from aliy80.localdomain(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0UItliQ7_1608186540) by smtp.aliyun-inc.com(127.0.0.1); Thu, 17 Dec 2020 14:29:01 +0800 From: Alex Shi To: akpm@linux-foundation.org Cc: Hugh Dickins , Johannes Weiner , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/3] mm/compaction: remove rcu_read_lock during page compaction Date: Thu, 17 Dec 2020 14:28:52 +0800 Message-Id: <1608186532-81218-3-git-send-email-alex.shi@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1608186532-81218-1-git-send-email-alex.shi@linux.alibaba.com> References: <1608186532-81218-1-git-send-email-alex.shi@linux.alibaba.com> 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: rcu_read_lock was used to guard memcg destory, now TestClearPageLRU could block this happen, so we don't need it. Remove it to reduce locking load in debugging mode. Signed-off-by: Alex Shi Cc: Hugh Dickins Cc: Johannes Weiner Cc: Andrew Morton Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Acked-by: Hugh Dickins --- mm/compaction.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 8049d3530812..02af220fb992 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -995,7 +995,6 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, if (!TestClearPageLRU(page)) goto isolate_fail_put; - rcu_read_lock(); lruvec = mem_cgroup_page_lruvec(page, pgdat); /* If we already hold the lock, we can skip some rechecking */ @@ -1005,7 +1004,6 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, compact_lock_irqsave(&lruvec->lru_lock, &flags, cc); locked = lruvec; - rcu_read_unlock(); lruvec_memcg_debug(lruvec, page); @@ -1026,8 +1024,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, SetPageLRU(page); goto isolate_fail_put; } - } else - rcu_read_unlock(); + } /* The whole page is taken off the LRU; skip the tail pages. */ if (PageCompound(page))