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 B2D64C433EF for ; Fri, 27 May 2022 01:11:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0DDC78D0003; Thu, 26 May 2022 21:11:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 08A2D8D0002; Thu, 26 May 2022 21:11:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EB8B18D0003; Thu, 26 May 2022 21:10:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id DC0648D0002 for ; Thu, 26 May 2022 21:10:59 -0400 (EDT) Received: from smtpin31.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id A509834E8F for ; Fri, 27 May 2022 01:10:59 +0000 (UTC) X-FDA: 79509743838.31.FB1B5E8 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf01.hostedemail.com (Postfix) with ESMTP id 42F4740040 for ; Fri, 27 May 2022 01:10:54 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4L8RXd5NnvzgYQC; Fri, 27 May 2022 09:09:21 +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 15.1.2375.24; Fri, 27 May 2022 09:10:54 +0800 Subject: Re: [PATCH] mm/page_table_check: fix accessing unmapped ptep To: Pasha Tatashin , Andrew Morton , , Matthew Wilcox CC: Matthew Wilcox , David Rientjes , linux-mm , LKML References: <20220526113350.30806-1-linmiaohe@huawei.com> <20220526111546.50102da288cccbe913cadbf4@linux-foundation.org> From: Miaohe Lin Message-ID: Date: Fri, 27 May 2022 09:10:53 +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: dggems701-chm.china.huawei.com (10.3.19.178) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Authentication-Results: imf01.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf01.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 42F4740040 X-Stat-Signature: b1awdx5qb9h3u1rbsfrdroajjucdwcuf X-HE-Tag: 1653613854-444741 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 2022/5/27 2:31, Pasha Tatashin wrote: >>> Miaohe, please store the ptep, or maybe drop this patch entirely. >> >> I think it's best to fix it. I rewrote the changelog as >> >> : ptep is unmapped too early, so ptep could theoretically be accessed while >> : it's unmapped. This might become a problem if/when CONFIG_HIGHPTE becomes >> : available on riscv. >> : >> : Fix it by deferring pte_unmap() until page table checking is done. >> >> I'll retain the Fixes:. This doesn't imply cc:stable in MM, and anyone >> who backports the original patchset will want to know about this fixup. > Makes sense. > > >> And I queued a fixup for the thing Matthew noticed. > Thank you Andrew. > Many thanks for all of your comments, review and fixup! :) > Pasha > . >