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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 9EFEAC433DB for ; Mon, 25 Jan 2021 02:04:41 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 45C232253A for ; Mon, 25 Jan 2021 02:04:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 45C232253A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 46C346B0005; Sun, 24 Jan 2021 21:04:39 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 41E266B0007; Sun, 24 Jan 2021 21:04:39 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 30C696B0008; Sun, 24 Jan 2021 21:04:39 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0124.hostedemail.com [216.40.44.124]) by kanga.kvack.org (Postfix) with ESMTP id 17B4B6B0005 for ; Sun, 24 Jan 2021 21:04:39 -0500 (EST) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id CB2DF180ACF0D for ; Mon, 25 Jan 2021 02:04:38 +0000 (UTC) X-FDA: 77742653436.16.pie36_4b0714127582 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin16.hostedemail.com (Postfix) with ESMTP id BAF8E100E6903 for ; Mon, 25 Jan 2021 02:04:38 +0000 (UTC) X-HE-Tag: pie36_4b0714127582 X-Filterd-Recvd-Size: 2861 Received: from szxga06-in.huawei.com (szxga06-in.huawei.com [45.249.212.32]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Mon, 25 Jan 2021 02:04:37 +0000 (UTC) Received: from DGGEMS406-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4DPCny1TLTzjBgB; Mon, 25 Jan 2021 10:03:34 +0800 (CST) Received: from [10.174.179.117] (10.174.179.117) by DGGEMS406-HUB.china.huawei.com (10.3.19.206) with Microsoft SMTP Server id 14.3.498.0; Mon, 25 Jan 2021 10:04:20 +0800 Subject: Re: [PATCH] mm: Fix potential pte_unmap_unlock pte error To: Andrew Morton CC: , , , , , Andi Kleen References: <20210109080118.20885-1-linmiaohe@huawei.com> <20210110171443.GC1914459@tassilo.jf.intel.com> <530deddf-705e-045d-f7c6-521531dced71@huawei.com> <2c691a87-42fd-63f6-6d7a-136be6572fab@huawei.com> <20210123180107.95f54cc0849a6d8c6afa16ee@linux-foundation.org> From: Miaohe Lin Message-ID: <372dc830-56ae-799c-6026-bb35c1803026@huawei.com> Date: Mon, 25 Jan 2021 10:04:19 +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: <20210123180107.95f54cc0849a6d8c6afa16ee@linux-foundation.org> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.117] X-CFilter-Loop: Reflected 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: Hi: On 2021/1/24 10:01, Andrew Morton wrote: > On Fri, 22 Jan 2021 16:27:23 +0800 Miaohe Lin wrote: > >> Hi Andrew: >> On 2021/1/14 10:51, Miaohe Lin wrote: >>> Hi: >>> On 2021/1/11 1:14, Andi Kleen wrote: >>>> On Sat, Jan 09, 2021 at 03:01:18AM -0500, Miaohe Lin wrote: >>>>> Since commit 42e4089c7890 ("x86/speculation/l1tf: Disallow non privileged >>>>> high MMIO PROT_NONE mappings"), when the first pfn modify is not allowed, >>>>> we would break the loop with pte unchanged. Then the wrong pte - 1 would >>>>> be passed to pte_unmap_unlock. >>>> >>>> Thanks. >>>> >>>> While the fix is correct, I'm not sure if it actually is a real bug. Is there >>>> any architecture that would do something else than unlocking the underlying >>>> page? If it's just the underlying page then it should be always the same >>>> page, so no bug. >>>> >>> >>> It's just a theoretical issue via code inspection. >> >> Should I send a new one without Cc statle or just drop this patch? Thanks. > > Your patch makes the code much less scary looking. I added Andi's > observation to the changelog, removed the cc:stable and queued it up, > thanks. > > . > Sounds reasonable. Many thanks for doing this!