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=-2.3 required=3.0 tests=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 3671DC1975A for ; Mon, 16 Mar 2020 09:13:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0BDA220658 for ; Mon, 16 Mar 2020 09:13:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0BDA220658 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 A11866B0003; Mon, 16 Mar 2020 05:13:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9C1C26B0005; Mon, 16 Mar 2020 05:13:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8FF2D6B0007; Mon, 16 Mar 2020 05:13:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 787076B0003 for ; Mon, 16 Mar 2020 05:13:50 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 45B71181AC9BF for ; Mon, 16 Mar 2020 09:13:50 +0000 (UTC) X-FDA: 76600663020.06.show02_45d43f1d970c X-HE-Tag: show02_45d43f1d970c X-Filterd-Recvd-Size: 1826 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf04.hostedemail.com (Postfix) with ESMTP for ; Mon, 16 Mar 2020 09:13:49 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 0627068CEC; Mon, 16 Mar 2020 10:13:48 +0100 (CET) Date: Mon, 16 Mar 2020 10:13:47 +0100 From: Christoph Hellwig To: Jason Gunthorpe Cc: Jerome Glisse , Ralph Campbell , Felix.Kuehling@amd.com, linux-mm@kvack.org, John Hubbard , dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, Christoph Hellwig , Philip Yang , Jason Gunthorpe Subject: Re: [PATCH hmm 8/8] mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handling Message-ID: <20200316091347.GH12439@lst.de> References: <20200311183506.3997-1-jgg@ziepe.ca> <20200311183506.3997-9-jgg@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200311183506.3997-9-jgg@ziepe.ca> User-Agent: Mutt/1.5.17 (2007-11-01) 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 Wed, Mar 11, 2020 at 03:35:06PM -0300, Jason Gunthorpe wrote: > From: Jason Gunthorpe > > Currently if a special PTE is encountered hmm_range_fault() immediately > returns EFAULT and sets the HMM_PFN_SPECIAL error output (which nothing > uses). > > EFAULT should only be returned after testing with hmm_pte_need_fault(). > > Also pte_devmap() and pte_special() are exclusive, and there is no need to > check IS_ENABLED, pte_special() is stubbed out to return false on > unsupported architectures. I think the right fix is to just kill HMM_PFN_SPECIAL and treat any fault on special ptes that aren't the zero page as an error.