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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 29498CA9EC9 for ; Mon, 4 Nov 2019 21:34:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DCF8620663 for ; Mon, 4 Nov 2019 21:34:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="qKL2SABn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DCF8620663 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7CA1E6B0003; Mon, 4 Nov 2019 16:34:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7A1616B0005; Mon, 4 Nov 2019 16:34:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 691086B0006; Mon, 4 Nov 2019 16:34:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0173.hostedemail.com [216.40.44.173]) by kanga.kvack.org (Postfix) with ESMTP id 537046B0003 for ; Mon, 4 Nov 2019 16:34:08 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id 17D02442B for ; Mon, 4 Nov 2019 21:34:08 +0000 (UTC) X-FDA: 76119898176.20.stick10_2400448277125 X-HE-Tag: stick10_2400448277125 X-Filterd-Recvd-Size: 5310 Received: from hqemgate15.nvidia.com (hqemgate15.nvidia.com [216.228.121.64]) by imf34.hostedemail.com (Postfix) with ESMTP for ; Mon, 4 Nov 2019 21:34:07 +0000 (UTC) Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate15.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 04 Nov 2019 13:34:10 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Mon, 04 Nov 2019 13:34:05 -0800 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Mon, 04 Nov 2019 13:34:05 -0800 Received: from [10.110.48.28] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 4 Nov 2019 21:34:05 +0000 Subject: Re: [PATCH v2 05/18] mm/gup: introduce pin_user_pages*() and FOLL_PIN To: Jason Gunthorpe CC: Jerome Glisse , Andrew Morton , Al Viro , Alex Williamson , Benjamin Herrenschmidt , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Christoph Hellwig , Dan Williams , Daniel Vetter , Dave Chinner , David Airlie , "David S . Miller" , Ira Weiny , Jan Kara , Jens Axboe , Jonathan Corbet , Magnus Karlsson , Mauro Carvalho Chehab , Michael Ellerman , Michal Hocko , Mike Kravetz , Paul Mackerras , Shuah Khan , Vlastimil Babka , , , , , , , , , , , , , LKML References: <20191103211813.213227-6-jhubbard@nvidia.com> <20191104173325.GD5134@redhat.com> <20191104191811.GI5134@redhat.com> <20191104195248.GA7731@redhat.com> <25ec4bc0-caaa-2a01-2ae7-2d79663a40e1@nvidia.com> <20191104203153.GB7731@redhat.com> <20191104203702.GG30938@ziepe.ca> <20191104211525.GJ30938@ziepe.ca> From: John Hubbard X-Nvconfidentiality: public Message-ID: Date: Mon, 4 Nov 2019 13:34:04 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191104211525.GJ30938@ziepe.ca> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1572903250; bh=vbo/OzrYq7woOdeOQXzDRocZ8qkmDZ2GrWck8Ge0GIw=; h=X-PGP-Universal:Subject:To:CC:References:From:X-Nvconfidentiality: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=qKL2SABndBuE0IlTwGECBEmaXKNt9+NUVq+WFlqtOQFVTiU7nDI02BQTOx0obKarz gpxOM5Y6JautiKfOu0FtwOKOgDIpCUi5YMn9VF5RbTl9cVhlQsO6c44+kqa1Gmkh8J VEKyKNOG6Vqk5nkQbEsBguPgBI2Ja3iUp52oe4dwNevVkVV3ApvpTePgu21U23nzfu yfLLAmDkD5PCoZMaxqbgr1s6DM7hOxhvmTI1aiChbyJF4tpKtWS0fJG0BnHlBMS2gJ uFSIwTdydwTYYvW23EYrvHjEOYVqNSM3f00rEJ3//HPrJcaJAle1+bmyry6JSVv/h0 e3DYAyiBVB40w== 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 11/4/19 1:15 PM, Jason Gunthorpe wrote: ... >> Right, and I thought about this when converting, and realized that the above >> code is working around the current gup.c limitations, which are "cannot support >> gup remote with FOLL_LONGTERM". > > But AFAICT it doesn't have a problem, the protection test is just too > strict, and I guess the control flow needs a bit of fixing.. > > The issue is this: > > static __always_inline long __get_user_pages_locked(): > { > if (locked) { > /* if VM_FAULT_RETRY can be returned, vmas become invalid */ > BUG_ON(vmas); > /* check caller initialized locked */ > BUG_ON(*locked != 1); > } > > > so remote could be written as: > > if (gup_flags & FOLL_LONGTERM) { > if (WARN_ON_ONCE(locked)) > return -EINVAL; > return __gup_longterm_locked(...) > } > > return __get_user_pages_locked(...) > > ?? Yes, that loosens it up just enough for the vfio case (which doesn't set "locked") to get through, great! OK, I'll put that (the above plus corresponding vfio fix) in a separate patch first. This should clear things up nicely. thanks, -- John Hubbard NVIDIA