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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,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 8C2D0C433E2 for ; Sun, 13 Sep 2020 13:37:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4655A2158C for ; Sun, 13 Sep 2020 13:37:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725950AbgIMNhE (ORCPT ); Sun, 13 Sep 2020 09:37:04 -0400 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:59970 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725931AbgIMNgk (ORCPT ); Sun, 13 Sep 2020 09:36:40 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=richard.weiyang@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0U8mKYn3_1600004196; Received: from localhost(mailfrom:richard.weiyang@linux.alibaba.com fp:SMTPD_---0U8mKYn3_1600004196) by smtp.aliyun-inc.com(127.0.0.1); Sun, 13 Sep 2020 21:36:37 +0800 From: Wei Yang To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Wei Yang Subject: [PATCH 1/2] mm/mmap: not necessary to check mapping separately Date: Sun, 13 Sep 2020 21:36:30 +0800 Message-Id: <20200913133631.37781-1-richard.weiyang@linux.alibaba.com> X-Mailer: git-send-email 2.20.1 (Apple Git-117) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org *root* with type of struct rb_root_cached is an element of *mapping* with type of struct address_space. This implies when we have a valid *root* it must be a part of valid *mapping*. So we can merge these two checks together to make the code more easy to read and to save some cpu cycles. Signed-off-by: Wei Yang --- mm/mmap.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 1922e6fce9e7..30b155098606 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -895,10 +895,9 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, anon_vma_interval_tree_post_update_vma(next); anon_vma_unlock_write(anon_vma); } - if (mapping) - i_mmap_unlock_write(mapping); if (root) { + i_mmap_unlock_write(mapping); uprobe_mmap(vma); if (adjust_next) -- 2.20.1 (Apple Git-117)