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 6504BC433F5 for ; Tue, 29 Mar 2022 13:27:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id ED3308D0003; Tue, 29 Mar 2022 09:27:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E83F98D0002; Tue, 29 Mar 2022 09:27:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D4BE18D0003; Tue, 29 Mar 2022 09:27:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id C31AE8D0002 for ; Tue, 29 Mar 2022 09:27:21 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 94C31240D3 for ; Tue, 29 Mar 2022 13:27:21 +0000 (UTC) X-FDA: 79297500282.10.A11EEF5 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by imf28.hostedemail.com (Postfix) with ESMTP id 880C5C001C for ; Tue, 29 Mar 2022 13:27:20 +0000 (UTC) Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4KSVj168RZz1GD3s; Tue, 29 Mar 2022 21:27:01 +0800 (CST) Received: from dggpemm500002.china.huawei.com (7.185.36.229) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Tue, 29 Mar 2022 21:27:18 +0800 Received: from [10.174.178.178] (10.174.178.178) by dggpemm500002.china.huawei.com (7.185.36.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Tue, 29 Mar 2022 21:27:17 +0800 Message-ID: <65501e99-0839-5f08-8a69-95e3c77c64ac@huawei.com> Date: Tue, 29 Mar 2022 21:27:17 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.0.3 Subject: Re: [PATCH 2/2] mm: fix contiguous memmap assumptions about alloc/free pages To: Matthew Wilcox CC: , , References: <20220329130928.266323-1-chenwandun@huawei.com> <20220329130928.266323-3-chenwandun@huawei.com> From: Chen Wandun In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.178] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500002.china.huawei.com (7.185.36.229) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 880C5C001C X-Stat-Signature: c43kh9jnhxq5e4bo9z7mym75e3741r4a Authentication-Results: imf28.hostedemail.com; dkim=none; spf=pass (imf28.hostedemail.com: domain of chenwandun@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=chenwandun@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspam-User: X-HE-Tag: 1648560440-991967 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 2022/3/29 21:08, Matthew Wilcox wrote: > On Tue, Mar 29, 2022 at 09:09:28PM +0800, Chen Wandun wrote: >> +#define page_nth(head, tail) (page_to_pfn(tail) - page_to_pfn(head)) > Could we avoid reintroducing page_nth()? It is a terrible name. how about compound_index ? >> @@ -1213,7 +1213,7 @@ static int free_tail_pages_check(struct page *head_page, struct page *page) >> ret = 0; >> goto out; >> } >> - switch (page - head_page) { >> + switch (page_nth(head_page, page)) { >> case 1: >> /* the first tail page: ->mapping may be compound_mapcount() */ >> if (unlikely(compound_mapcount(page))) { > This is the only place you use it. I'd suggest free_tail_pages_check() > should take 'i' as its second parameter instead of 'page + i', then > there's no need to convert back to i. OK， I will send v2， but I'm not sure whether similar function like page_nth is needed elsewhere > > .