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,SPF_HELO_NONE,SPF_PASS, 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 E758FC433B4 for ; Tue, 18 May 2021 13:24:32 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8E9C86113C for ; Tue, 18 May 2021 13:24:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8E9C86113C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E7D158E0025; Tue, 18 May 2021 09:24:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E54978E0023; Tue, 18 May 2021 09:24:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D449F8E0025; Tue, 18 May 2021 09:24:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0131.hostedemail.com [216.40.44.131]) by kanga.kvack.org (Postfix) with ESMTP id A3A1C8E0023 for ; Tue, 18 May 2021 09:24:31 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 434338249980 for ; Tue, 18 May 2021 13:24:31 +0000 (UTC) X-FDA: 78154421142.26.5A56C72 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf18.hostedemail.com (Postfix) with ESMTP id DDADF2000241 for ; Tue, 18 May 2021 13:24:29 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 3DA4567373; Tue, 18 May 2021 15:24:29 +0200 (CEST) Date: Tue, 18 May 2021 15:24:28 +0200 From: Christoph Hellwig To: Thomas =?iso-8859-1?Q?Hellstr=F6m?= Cc: Christoph Hellwig , Serge Belyshev , Peter Zijlstra , Daniel Vetter , intel-gfx@lists.freedesktop.org, Chris Wilson , linux-mm@kvack.org, dri-devel@lists.freedesktop.org, Andrew Morton Subject: Re: [Intel-gfx] [PATCH 4/4] i915: fix remap_io_sg to verify the pgprot Message-ID: <20210518132428.GD2617@lst.de> References: <20210326055505.1424432-1-hch@lst.de> <20210326055505.1424432-5-hch@lst.de> <87pmxqiry6.fsf@depni.sinp.msu.ru> <20210517123716.GD15150@lst.de> <87lf8dik15.fsf@depni.sinp.msu.ru> <20210517131137.GA19451@lst.de> <976fb38a-7780-6ca6-d602-a5f02c0938c9@linux.intel.com> <6adf9658-25b7-16ef-4b88-fa3911d06b74@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <6adf9658-25b7-16ef-4b88-fa3911d06b74@linux.intel.com> User-Agent: Mutt/1.5.17 (2007-11-01) Authentication-Results: imf18.hostedemail.com; dkim=none; dmarc=none; spf=none (imf18.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: DDADF2000241 X-Stat-Signature: 6443n86dp6yf5kpm39j6zfhkrwu4poe8 X-HE-Tag: 1621344269-467476 Content-Transfer-Encoding: quoted-printable 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 Tue, May 18, 2021 at 08:46:44AM +0200, Thomas Hellstr=F6m wrote: > And worse, if we prefault a user-space buffer object map using=20 > remap_io_sg() and then zap some ptes using madvise(), the next time tho= se=20 > ptes are accessed, we'd trigger a new call to remap_io_sg() which would= now=20 > find already populated ptes. While the old code looks to just silently=20 > overwrite those, it looks like the new code would BUG in remap_pte_rang= e()? How can you zap the PTEs using madvise?