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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3FE7C433EF for ; Tue, 15 Mar 2022 12:30:54 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3B6B28D0002; Tue, 15 Mar 2022 08:30:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 365F18D0001; Tue, 15 Mar 2022 08:30:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 22D018D0002; Tue, 15 Mar 2022 08:30:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0130.hostedemail.com [216.40.44.130]) by kanga.kvack.org (Postfix) with ESMTP id 12F478D0001 for ; Tue, 15 Mar 2022 08:30:54 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id C15DDA231D for ; Tue, 15 Mar 2022 12:30:53 +0000 (UTC) X-FDA: 79246554786.20.2BA57DC Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by imf02.hostedemail.com (Postfix) with ESMTP id 75E548002D for ; Tue, 15 Mar 2022 12:30:52 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4KHt0w6pwsz1GCCL; Tue, 15 Mar 2022 20:25:52 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Tue, 15 Mar 2022 20:30:49 +0800 Subject: Re: [PATCH] mm/mlock: remove unneeded start >= vma->vm_end check To: Matthew Wilcox CC: , , , References: <20220314153223.53753-1-linmiaohe@huawei.com> From: Miaohe Lin Message-ID: Date: Tue, 15 Mar 2022 20:30:49 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: 75E548002D X-Stat-Signature: m95d6ok8uzb9jhkkdx5oxecy9u119saq X-Rspam-User: Authentication-Results: imf02.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf02.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-Rspamd-Server: rspam02 X-HE-Tag: 1647347452-477323 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 2022/3/15 0:17, Matthew Wilcox wrote: > On Mon, Mar 14, 2022 at 11:32:23PM +0800, Miaohe Lin wrote: >> If find_vma returns a vma, it must satisfies that start < vma->vm_end. >> Since vma list is sorted in the ascending order, so we will never see >> start >= vma->vm_end here. Remove this unneeded check. > > faulty logic; vm_start + len might wrap. Many thanks for comment. I agree with you about "vm_start + len" might wrap. But what I mean here is that we will never see "start" >= vma->vm_end here as find_vma guarantees this. And I leave the "start + len <= vma->vm_start" check untouched. So my cleanup should be right. Or am I miss something? Thanks. > > . >