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 DDBC6C433EF for ; Thu, 31 Mar 2022 01:50:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 388D36B0074; Wed, 30 Mar 2022 21:50:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3387A8D0002; Wed, 30 Mar 2022 21:50:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 228CC8D0001; Wed, 30 Mar 2022 21:50:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0093.hostedemail.com [216.40.44.93]) by kanga.kvack.org (Postfix) with ESMTP id 1412F6B0074 for ; Wed, 30 Mar 2022 21:50:41 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id C213E182D2106 for ; Thu, 31 Mar 2022 01:50:40 +0000 (UTC) X-FDA: 79303002240.24.79132C3 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by imf29.hostedemail.com (Postfix) with ESMTP id 1342212000E for ; Thu, 31 Mar 2022 01:50:39 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4KTR8B6cWNz1GD0d; Thu, 31 Mar 2022 09:50:18 +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; Thu, 31 Mar 2022 09:50:36 +0800 Subject: Re: [PATCH] mm/mlock: remove unneeded start >= vma->vm_end check From: Miaohe Lin To: Matthew Wilcox , Andrew Morton CC: , , References: <20220314153223.53753-1-linmiaohe@huawei.com> Message-ID: <602a1658-9b29-1752-d5a0-c5dd338fcc4c@huawei.com> Date: Thu, 31 Mar 2022 09:50:36 +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: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 1342212000E X-Stat-Signature: qztnesqidstjpo77mytdptmn91g6uhjw X-Rspam-User: Authentication-Results: imf29.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf29.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-HE-Tag: 1648691439-149172 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 20:30, Miaohe Lin wrote: > 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? > friendly ping. :) > Thanks. > >> >> . >> >