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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 54B9CC17448 for ; Tue, 12 Nov 2019 20:43:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 288A1206A3 for ; Tue, 12 Nov 2019 20:43:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="Ia/Hl3Z1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727021AbfKLUnp (ORCPT ); Tue, 12 Nov 2019 15:43:45 -0500 Received: from mail-qt1-f193.google.com ([209.85.160.193]:37123 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726659AbfKLUnl (ORCPT ); Tue, 12 Nov 2019 15:43:41 -0500 Received: by mail-qt1-f193.google.com with SMTP id g50so21297612qtb.4 for ; Tue, 12 Nov 2019 12:43:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=kGcjnenI+EnnAHWMcItB24mxm55INky4C94Ykv4geg4=; b=Ia/Hl3Z1HOGYiq6KoluUd9uZCGKzwQBgBr5JQ7I5KyZEUZP07fiLx9egiGiglXV9yp zwduhp53vyEcd290QPaERf3wZ21mOf61BVNQbg6GVzWjLkWaYtjFFrAZ/kB/sX/TsV0O Cqh6vZK9nd1Vig8r0syQpzeADiWtdjhU8C1qoZqr93PSItmh35/j4piNjOHcIgDaKDz3 2BaPDGhVa8atEOsvR55GHtOxdcr+RnZlO25xW0gJoiJutB0sYZDed0fX6gxPxoxhf5Zl 1FXBtMQo3iHNaStug4eqwxrgV4Z4sqg89JFN5ijz+6oI5UdbjHNjva//V05ajuQKORqi pELA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=kGcjnenI+EnnAHWMcItB24mxm55INky4C94Ykv4geg4=; b=eajSG5GKWp7XS1vi/dQVfQ/G3ZusTFjdnt6AFqfxDtyB5n3PNV0RlBgwxQv5GSSNzQ qVToqF3iYLaXSe0kZZITR2FvcjjbQJMkMqN8N8iIBHQzoDByEFP+7AuacveGREabXtIc RgTHjMZtLwdHXNvJOx7txHMkP/goIMLQzT7P0NU6qyWxvMAb2pIxHLZvkbbplPAy9AkU I8OXqJqGaMQv0Ouhb6fsXkSVzWboaiM49m7ziaaIdfwK9YonBfVJBYWVOIz5GqzGZvb4 DpNPzfaVtk55L255rUbCaWmic4QfwFjAIDYZS0OXf0nAyI3jAsPTmCMOA9jO3/W9eJ0m USHA== X-Gm-Message-State: APjAAAWPipJWn4yPkVPQLMgwWcePfV4yTUCfFc63/6xwmENEYV6HoIJF D0hrd+oBYjRnHIfgqxhs3CPt1w== X-Google-Smtp-Source: APXvYqyV99P4cYBxqwR0yk0Vl7NSO/G/hGYwr7orI5pSazTDzznvIwLj5yKe4F2N3m9e7NI6fV/HBQ== X-Received: by 2002:ac8:1ba5:: with SMTP id z34mr33733259qtj.162.1573591419675; Tue, 12 Nov 2019 12:43:39 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-162-113-180.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.113.180]) by smtp.gmail.com with ESMTPSA id u22sm10020470qtb.59.2019.11.12.12.43.38 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 12 Nov 2019 12:43:39 -0800 (PST) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1iUd0k-00046s-Fb; Tue, 12 Nov 2019 16:43:38 -0400 Date: Tue, 12 Nov 2019 16:43:38 -0400 From: Jason Gunthorpe To: John Hubbard Cc: 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 , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Magnus Karlsson , Mauro Carvalho Chehab , Michael Ellerman , Michal Hocko , Mike Kravetz , Paul Mackerras , Shuah Khan , Vlastimil Babka , bpf@vger.kernel.org, dri-devel@lists.freedesktop.org, kvm@vger.kernel.org, linux-block@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org, linux-rdma@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-mm@kvack.org, LKML Subject: Re: [PATCH v3 08/23] vfio, mm: fix get_user_pages_remote() and FOLL_LONGTERM Message-ID: <20191112204338.GE5584@ziepe.ca> References: <20191112000700.3455038-1-jhubbard@nvidia.com> <20191112000700.3455038-9-jhubbard@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191112000700.3455038-9-jhubbard@nvidia.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Mon, Nov 11, 2019 at 04:06:45PM -0800, John Hubbard wrote: > As it says in the updated comment in gup.c: current FOLL_LONGTERM > behavior is incompatible with FAULT_FLAG_ALLOW_RETRY because of the > FS DAX check requirement on vmas. > > However, the corresponding restriction in get_user_pages_remote() was > slightly stricter than is actually required: it forbade all > FOLL_LONGTERM callers, but we can actually allow FOLL_LONGTERM callers > that do not set the "locked" arg. > > Update the code and comments accordingly, and update the VFIO caller > to take advantage of this, fixing a bug as a result: the VFIO caller > is logically a FOLL_LONGTERM user. > > Thanks to Jason Gunthorpe for pointing out a clean way to fix this. > > Suggested-by: Jason Gunthorpe > Cc: Jerome Glisse > Cc: Ira Weiny > Signed-off-by: John Hubbard > --- > drivers/vfio/vfio_iommu_type1.c | 30 +++++++++++++----------------- > mm/gup.c | 13 ++++++++----- > 2 files changed, 21 insertions(+), 22 deletions(-) This matches what I thought, but I think DanW should check it too, and the vfio users should test.. > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index d864277ea16f..017689b7c32b 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -348,24 +348,20 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr, > flags |= FOLL_WRITE; > > down_read(&mm->mmap_sem); > - if (mm == current->mm) { > - ret = get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page, > - vmas); > - } else { > - ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page, > - vmas, NULL); > - /* > - * The lifetime of a vaddr_get_pfn() page pin is > - * userspace-controlled. In the fs-dax case this could > - * lead to indefinite stalls in filesystem operations. > - * Disallow attempts to pin fs-dax pages via this > - * interface. > - */ > - if (ret > 0 && vma_is_fsdax(vmas[0])) { > - ret = -EOPNOTSUPP; > - put_page(page[0]); > - } > + ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags | FOLL_LONGTERM, > + page, vmas, NULL); > + /* > + * The lifetime of a vaddr_get_pfn() page pin is > + * userspace-controlled. In the fs-dax case this could > + * lead to indefinite stalls in filesystem operations. > + * Disallow attempts to pin fs-dax pages via this > + * interface. > + */ > + if (ret > 0 && vma_is_fsdax(vmas[0])) { > + ret = -EOPNOTSUPP; > + put_page(page[0]); > } AFAIK this chunk is redundant now as it is some hack to emulate FOLL_LONGTERM? So vmas can be deleted too. Also unclear why this function has this: up_read(&mm->mmap_sem); if (ret == 1) { *pfn = page_to_pfn(page[0]); return 0; } down_read(&mm->mmap_sem); Jason 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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 9E782C43331 for ; Tue, 12 Nov 2019 20:46:41 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 49EDF2067B for ; Tue, 12 Nov 2019 20:46:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="Ia/Hl3Z1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 49EDF2067B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 47CKXv0JBKzF5fT for ; Wed, 13 Nov 2019 07:46:39 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=ziepe.ca (client-ip=2607:f8b0:4864:20::841; helo=mail-qt1-x841.google.com; envelope-from=jgg@ziepe.ca; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; secure) header.d=ziepe.ca header.i=@ziepe.ca header.b="Ia/Hl3Z1"; dkim-atps=neutral Received: from mail-qt1-x841.google.com (mail-qt1-x841.google.com [IPv6:2607:f8b0:4864:20::841]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 47CKTW4CF5zF3K0 for ; Wed, 13 Nov 2019 07:43:43 +1100 (AEDT) Received: by mail-qt1-x841.google.com with SMTP id o11so21270782qtr.11 for ; Tue, 12 Nov 2019 12:43:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=kGcjnenI+EnnAHWMcItB24mxm55INky4C94Ykv4geg4=; b=Ia/Hl3Z1HOGYiq6KoluUd9uZCGKzwQBgBr5JQ7I5KyZEUZP07fiLx9egiGiglXV9yp zwduhp53vyEcd290QPaERf3wZ21mOf61BVNQbg6GVzWjLkWaYtjFFrAZ/kB/sX/TsV0O Cqh6vZK9nd1Vig8r0syQpzeADiWtdjhU8C1qoZqr93PSItmh35/j4piNjOHcIgDaKDz3 2BaPDGhVa8atEOsvR55GHtOxdcr+RnZlO25xW0gJoiJutB0sYZDed0fX6gxPxoxhf5Zl 1FXBtMQo3iHNaStug4eqwxrgV4Z4sqg89JFN5ijz+6oI5UdbjHNjva//V05ajuQKORqi pELA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=kGcjnenI+EnnAHWMcItB24mxm55INky4C94Ykv4geg4=; b=K7xnHXYSP6kWkcpGLzPDPtZO4/QNPdeMGvFkxXuafyv3ELFkHRmNyVp16he/jKuoTH m0HO7UNeTkHeEdXiy4SAE2Fp8J4K8rFYQ4qPEHqn41HlgBz0aIAWyQKlPevlxhm/I8s8 bK75YTwJIZbR6/1WQ3STgoPb82PVI0WHs3edaGC9uyqkrY2NytnokvcpppHoayDXCmg/ vUUOMGg66UqTueOYfWVaILqA6szR/7JHdebkWSmL0AWihzkvq24cPFOVLIrL3kVDlwG8 LGW54XCnYps6cRH0ASKCelEet0WIqpWRfazSZkJUebpscSsiLa4L0CUJvWz/dkVp+caY 9VqQ== X-Gm-Message-State: APjAAAWIQYqE2b0dGG3M1lX+TOI87fJxdd3XPDMhOG3Y89YO1oGkjfVm cn5+84Yt+X81nkINv3jBWaGXuw== X-Google-Smtp-Source: APXvYqyV99P4cYBxqwR0yk0Vl7NSO/G/hGYwr7orI5pSazTDzznvIwLj5yKe4F2N3m9e7NI6fV/HBQ== X-Received: by 2002:ac8:1ba5:: with SMTP id z34mr33733259qtj.162.1573591419675; Tue, 12 Nov 2019 12:43:39 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-162-113-180.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.113.180]) by smtp.gmail.com with ESMTPSA id u22sm10020470qtb.59.2019.11.12.12.43.38 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 12 Nov 2019 12:43:39 -0800 (PST) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1iUd0k-00046s-Fb; Tue, 12 Nov 2019 16:43:38 -0400 Date: Tue, 12 Nov 2019 16:43:38 -0400 From: Jason Gunthorpe To: John Hubbard Subject: Re: [PATCH v3 08/23] vfio, mm: fix get_user_pages_remote() and FOLL_LONGTERM Message-ID: <20191112204338.GE5584@ziepe.ca> References: <20191112000700.3455038-1-jhubbard@nvidia.com> <20191112000700.3455038-9-jhubbard@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191112000700.3455038-9-jhubbard@nvidia.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michal Hocko , Jan Kara , kvm@vger.kernel.org, linux-doc@vger.kernel.org, David Airlie , Dave Chinner , dri-devel@lists.freedesktop.org, LKML , linux-mm@kvack.org, Paul Mackerras , linux-kselftest@vger.kernel.org, Ira Weiny , Jonathan Corbet , linux-rdma@vger.kernel.org, Christoph Hellwig , Vlastimil Babka , =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= , linux-media@vger.kernel.org, Shuah Khan , linux-block@vger.kernel.org, =?utf-8?B?SsOpcsO0bWU=?= Glisse , Al Viro , Dan Williams , Mauro Carvalho Chehab , bpf@vger.kernel.org, Magnus Karlsson , Jens Axboe , netdev@vger.kernel.org, Alex Williamson , Daniel Vetter , linux-fsdevel@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S . Miller" , Mike Kravetz Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, Nov 11, 2019 at 04:06:45PM -0800, John Hubbard wrote: > As it says in the updated comment in gup.c: current FOLL_LONGTERM > behavior is incompatible with FAULT_FLAG_ALLOW_RETRY because of the > FS DAX check requirement on vmas. > > However, the corresponding restriction in get_user_pages_remote() was > slightly stricter than is actually required: it forbade all > FOLL_LONGTERM callers, but we can actually allow FOLL_LONGTERM callers > that do not set the "locked" arg. > > Update the code and comments accordingly, and update the VFIO caller > to take advantage of this, fixing a bug as a result: the VFIO caller > is logically a FOLL_LONGTERM user. > > Thanks to Jason Gunthorpe for pointing out a clean way to fix this. > > Suggested-by: Jason Gunthorpe > Cc: Jerome Glisse > Cc: Ira Weiny > Signed-off-by: John Hubbard > --- > drivers/vfio/vfio_iommu_type1.c | 30 +++++++++++++----------------- > mm/gup.c | 13 ++++++++----- > 2 files changed, 21 insertions(+), 22 deletions(-) This matches what I thought, but I think DanW should check it too, and the vfio users should test.. > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index d864277ea16f..017689b7c32b 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -348,24 +348,20 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr, > flags |= FOLL_WRITE; > > down_read(&mm->mmap_sem); > - if (mm == current->mm) { > - ret = get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page, > - vmas); > - } else { > - ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page, > - vmas, NULL); > - /* > - * The lifetime of a vaddr_get_pfn() page pin is > - * userspace-controlled. In the fs-dax case this could > - * lead to indefinite stalls in filesystem operations. > - * Disallow attempts to pin fs-dax pages via this > - * interface. > - */ > - if (ret > 0 && vma_is_fsdax(vmas[0])) { > - ret = -EOPNOTSUPP; > - put_page(page[0]); > - } > + ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags | FOLL_LONGTERM, > + page, vmas, NULL); > + /* > + * The lifetime of a vaddr_get_pfn() page pin is > + * userspace-controlled. In the fs-dax case this could > + * lead to indefinite stalls in filesystem operations. > + * Disallow attempts to pin fs-dax pages via this > + * interface. > + */ > + if (ret > 0 && vma_is_fsdax(vmas[0])) { > + ret = -EOPNOTSUPP; > + put_page(page[0]); > } AFAIK this chunk is redundant now as it is some hack to emulate FOLL_LONGTERM? So vmas can be deleted too. Also unclear why this function has this: up_read(&mm->mmap_sem); if (ret == 1) { *pfn = page_to_pfn(page[0]); return 0; } down_read(&mm->mmap_sem); Jason From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [PATCH v3 08/23] vfio, mm: fix get_user_pages_remote() and FOLL_LONGTERM Date: Tue, 12 Nov 2019 16:43:38 -0400 Message-ID: <20191112204338.GE5584@ziepe.ca> References: <20191112000700.3455038-1-jhubbard@nvidia.com> <20191112000700.3455038-9-jhubbard@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20191112000700.3455038-9-jhubbard@nvidia.com> Sender: netdev-owner@vger.kernel.org To: John Hubbard Cc: 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 , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Magnus Karlsson , Mauro Carvalho Chehab , Michael Ellerman List-Id: dri-devel@lists.freedesktop.org On Mon, Nov 11, 2019 at 04:06:45PM -0800, John Hubbard wrote: > As it says in the updated comment in gup.c: current FOLL_LONGTERM > behavior is incompatible with FAULT_FLAG_ALLOW_RETRY because of the > FS DAX check requirement on vmas. > > However, the corresponding restriction in get_user_pages_remote() was > slightly stricter than is actually required: it forbade all > FOLL_LONGTERM callers, but we can actually allow FOLL_LONGTERM callers > that do not set the "locked" arg. > > Update the code and comments accordingly, and update the VFIO caller > to take advantage of this, fixing a bug as a result: the VFIO caller > is logically a FOLL_LONGTERM user. > > Thanks to Jason Gunthorpe for pointing out a clean way to fix this. > > Suggested-by: Jason Gunthorpe > Cc: Jerome Glisse > Cc: Ira Weiny > Signed-off-by: John Hubbard > --- > drivers/vfio/vfio_iommu_type1.c | 30 +++++++++++++----------------- > mm/gup.c | 13 ++++++++----- > 2 files changed, 21 insertions(+), 22 deletions(-) This matches what I thought, but I think DanW should check it too, and the vfio users should test.. > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index d864277ea16f..017689b7c32b 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -348,24 +348,20 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr, > flags |= FOLL_WRITE; > > down_read(&mm->mmap_sem); > - if (mm == current->mm) { > - ret = get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page, > - vmas); > - } else { > - ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page, > - vmas, NULL); > - /* > - * The lifetime of a vaddr_get_pfn() page pin is > - * userspace-controlled. In the fs-dax case this could > - * lead to indefinite stalls in filesystem operations. > - * Disallow attempts to pin fs-dax pages via this > - * interface. > - */ > - if (ret > 0 && vma_is_fsdax(vmas[0])) { > - ret = -EOPNOTSUPP; > - put_page(page[0]); > - } > + ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags | FOLL_LONGTERM, > + page, vmas, NULL); > + /* > + * The lifetime of a vaddr_get_pfn() page pin is > + * userspace-controlled. In the fs-dax case this could > + * lead to indefinite stalls in filesystem operations. > + * Disallow attempts to pin fs-dax pages via this > + * interface. > + */ > + if (ret > 0 && vma_is_fsdax(vmas[0])) { > + ret = -EOPNOTSUPP; > + put_page(page[0]); > } AFAIK this chunk is redundant now as it is some hack to emulate FOLL_LONGTERM? So vmas can be deleted too. Also unclear why this function has this: up_read(&mm->mmap_sem); if (ret == 1) { *pfn = page_to_pfn(page[0]); return 0; } down_read(&mm->mmap_sem); Jason 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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 852A1C43331 for ; Wed, 13 Nov 2019 07:56:55 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 64C41206B6 for ; Wed, 13 Nov 2019 07:56:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 64C41206B6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 164A76EB20; Wed, 13 Nov 2019 07:56:48 +0000 (UTC) Received: from mail-qt1-x841.google.com (mail-qt1-x841.google.com [IPv6:2607:f8b0:4864:20::841]) by gabe.freedesktop.org (Postfix) with ESMTPS id 871156E13F for ; Tue, 12 Nov 2019 20:43:40 +0000 (UTC) Received: by mail-qt1-x841.google.com with SMTP id i17so9768341qtq.1 for ; Tue, 12 Nov 2019 12:43:40 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=kGcjnenI+EnnAHWMcItB24mxm55INky4C94Ykv4geg4=; b=eYlGvY/uSU3xXBnydDreABxPk5AimWjnCNJnc/WJrmWIVaMXT71RyCMkDiZ2s8RvoI oJVByTmdmxOLiE0zbJhnXTw2H5lObKKfp+C1HGxZnY5kz8Edg7UJtAvGz92IroCgbeNa COkButnqnD0lGAVZMGTciX8ncaFnsoQGdp7p40DL3K3Tiomzgsh48a/nLAYcrApHF4s+ 30g+YipAbaLoAGUexGe2jpvzJC2Z+OF0Yda9dVaJF5DqttD7gLpZ8pi0DCm1hXbt5hn5 ON5SxiHZCTCTlG/w5wGlyxi3CEMBttVTfZN3S/pLC76jAbL7ERw6kONE0D4VMQulRheC Lf7g== X-Gm-Message-State: APjAAAVLfzIXgIG7Ed9cTCdqkbVz2FEMH9PF9IAGW1WglsalTXx3xV3y MGqvjWqOxW6r69T6xeZbtNEEeA== X-Google-Smtp-Source: APXvYqyV99P4cYBxqwR0yk0Vl7NSO/G/hGYwr7orI5pSazTDzznvIwLj5yKe4F2N3m9e7NI6fV/HBQ== X-Received: by 2002:ac8:1ba5:: with SMTP id z34mr33733259qtj.162.1573591419675; Tue, 12 Nov 2019 12:43:39 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-162-113-180.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.113.180]) by smtp.gmail.com with ESMTPSA id u22sm10020470qtb.59.2019.11.12.12.43.38 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 12 Nov 2019 12:43:39 -0800 (PST) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1iUd0k-00046s-Fb; Tue, 12 Nov 2019 16:43:38 -0400 Date: Tue, 12 Nov 2019 16:43:38 -0400 From: Jason Gunthorpe To: John Hubbard Subject: Re: [PATCH v3 08/23] vfio, mm: fix get_user_pages_remote() and FOLL_LONGTERM Message-ID: <20191112204338.GE5584@ziepe.ca> References: <20191112000700.3455038-1-jhubbard@nvidia.com> <20191112000700.3455038-9-jhubbard@nvidia.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191112000700.3455038-9-jhubbard@nvidia.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Mailman-Approved-At: Wed, 13 Nov 2019 07:55:45 +0000 X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=kGcjnenI+EnnAHWMcItB24mxm55INky4C94Ykv4geg4=; b=Ia/Hl3Z1HOGYiq6KoluUd9uZCGKzwQBgBr5JQ7I5KyZEUZP07fiLx9egiGiglXV9yp zwduhp53vyEcd290QPaERf3wZ21mOf61BVNQbg6GVzWjLkWaYtjFFrAZ/kB/sX/TsV0O Cqh6vZK9nd1Vig8r0syQpzeADiWtdjhU8C1qoZqr93PSItmh35/j4piNjOHcIgDaKDz3 2BaPDGhVa8atEOsvR55GHtOxdcr+RnZlO25xW0gJoiJutB0sYZDed0fX6gxPxoxhf5Zl 1FXBtMQo3iHNaStug4eqwxrgV4Z4sqg89JFN5ijz+6oI5UdbjHNjva//V05ajuQKORqi pELA== X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michal Hocko , Jan Kara , kvm@vger.kernel.org, linux-doc@vger.kernel.org, David Airlie , Dave Chinner , dri-devel@lists.freedesktop.org, LKML , linux-mm@kvack.org, Paul Mackerras , linux-kselftest@vger.kernel.org, Ira Weiny , Jonathan Corbet , linux-rdma@vger.kernel.org, Michael Ellerman , Christoph Hellwig , Vlastimil Babka , =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= , linux-media@vger.kernel.org, Shuah Khan , linux-block@vger.kernel.org, =?utf-8?B?SsOpcsO0bWU=?= Glisse , Al Viro , Dan Williams , Mauro Carvalho Chehab , bpf@vger.kernel.org, Magnus Karlsson , Jens Axboe , netdev@vger.kernel.org, Alex Williamson , linux-fsdevel@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S . Miller" , Mike Kravetz Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Message-ID: <20191112204338.eYske5EB73XoqoNI_5Mj-bfJ3UdVKGXcWrpB6dZMg0s@z> T24gTW9uLCBOb3YgMTEsIDIwMTkgYXQgMDQ6MDY6NDVQTSAtMDgwMCwgSm9obiBIdWJiYXJkIHdy b3RlOgo+IEFzIGl0IHNheXMgaW4gdGhlIHVwZGF0ZWQgY29tbWVudCBpbiBndXAuYzogY3VycmVu dCBGT0xMX0xPTkdURVJNCj4gYmVoYXZpb3IgaXMgaW5jb21wYXRpYmxlIHdpdGggRkFVTFRfRkxB R19BTExPV19SRVRSWSBiZWNhdXNlIG9mIHRoZQo+IEZTIERBWCBjaGVjayByZXF1aXJlbWVudCBv biB2bWFzLgo+IAo+IEhvd2V2ZXIsIHRoZSBjb3JyZXNwb25kaW5nIHJlc3RyaWN0aW9uIGluIGdl dF91c2VyX3BhZ2VzX3JlbW90ZSgpIHdhcwo+IHNsaWdodGx5IHN0cmljdGVyIHRoYW4gaXMgYWN0 dWFsbHkgcmVxdWlyZWQ6IGl0IGZvcmJhZGUgYWxsCj4gRk9MTF9MT05HVEVSTSBjYWxsZXJzLCBi dXQgd2UgY2FuIGFjdHVhbGx5IGFsbG93IEZPTExfTE9OR1RFUk0gY2FsbGVycwo+IHRoYXQgZG8g bm90IHNldCB0aGUgImxvY2tlZCIgYXJnLgo+IAo+IFVwZGF0ZSB0aGUgY29kZSBhbmQgY29tbWVu dHMgYWNjb3JkaW5nbHksIGFuZCB1cGRhdGUgdGhlIFZGSU8gY2FsbGVyCj4gdG8gdGFrZSBhZHZh bnRhZ2Ugb2YgdGhpcywgZml4aW5nIGEgYnVnIGFzIGEgcmVzdWx0OiB0aGUgVkZJTyBjYWxsZXIK PiBpcyBsb2dpY2FsbHkgYSBGT0xMX0xPTkdURVJNIHVzZXIuCj4gCj4gVGhhbmtzIHRvIEphc29u IEd1bnRob3JwZSBmb3IgcG9pbnRpbmcgb3V0IGEgY2xlYW4gd2F5IHRvIGZpeCB0aGlzLgo+IAo+ IFN1Z2dlc3RlZC1ieTogSmFzb24gR3VudGhvcnBlIDxqZ2dAemllcGUuY2E+Cj4gQ2M6IEplcm9t ZSBHbGlzc2UgPGpnbGlzc2VAcmVkaGF0LmNvbT4KPiBDYzogSXJhIFdlaW55IDxpcmEud2VpbnlA aW50ZWwuY29tPgo+IFNpZ25lZC1vZmYtYnk6IEpvaG4gSHViYmFyZCA8amh1YmJhcmRAbnZpZGlh LmNvbT4KPiAtLS0KPiAgZHJpdmVycy92ZmlvL3ZmaW9faW9tbXVfdHlwZTEuYyB8IDMwICsrKysr KysrKysrKystLS0tLS0tLS0tLS0tLS0tLQo+ICBtbS9ndXAuYyAgICAgICAgICAgICAgICAgICAg ICAgIHwgMTMgKysrKysrKystLS0tLQo+ICAyIGZpbGVzIGNoYW5nZWQsIDIxIGluc2VydGlvbnMo KyksIDIyIGRlbGV0aW9ucygtKQoKVGhpcyBtYXRjaGVzIHdoYXQgSSB0aG91Z2h0LCBidXQgSSB0 aGluayBEYW5XIHNob3VsZCBjaGVjayBpdCB0b28sIGFuZAp0aGUgdmZpbyB1c2VycyBzaG91bGQg dGVzdC4uCgo+IGRpZmYgLS1naXQgYS9kcml2ZXJzL3ZmaW8vdmZpb19pb21tdV90eXBlMS5jIGIv ZHJpdmVycy92ZmlvL3ZmaW9faW9tbXVfdHlwZTEuYwo+IGluZGV4IGQ4NjQyNzdlYTE2Zi4uMDE3 Njg5YjdjMzJiIDEwMDY0NAo+IC0tLSBhL2RyaXZlcnMvdmZpby92ZmlvX2lvbW11X3R5cGUxLmMK PiArKysgYi9kcml2ZXJzL3ZmaW8vdmZpb19pb21tdV90eXBlMS5jCj4gQEAgLTM0OCwyNCArMzQ4 LDIwIEBAIHN0YXRpYyBpbnQgdmFkZHJfZ2V0X3BmbihzdHJ1Y3QgbW1fc3RydWN0ICptbSwgdW5z aWduZWQgbG9uZyB2YWRkciwKPiAgCQlmbGFncyB8PSBGT0xMX1dSSVRFOwo+ICAKPiAgCWRvd25f cmVhZCgmbW0tPm1tYXBfc2VtKTsKPiAtCWlmIChtbSA9PSBjdXJyZW50LT5tbSkgewo+IC0JCXJl dCA9IGdldF91c2VyX3BhZ2VzKHZhZGRyLCAxLCBmbGFncyB8IEZPTExfTE9OR1RFUk0sIHBhZ2Us Cj4gLQkJCQkgICAgIHZtYXMpOwo+IC0JfSBlbHNlIHsKPiAtCQlyZXQgPSBnZXRfdXNlcl9wYWdl c19yZW1vdGUoTlVMTCwgbW0sIHZhZGRyLCAxLCBmbGFncywgcGFnZSwKPiAtCQkJCQkgICAgdm1h cywgTlVMTCk7Cj4gLQkJLyoKPiAtCQkgKiBUaGUgbGlmZXRpbWUgb2YgYSB2YWRkcl9nZXRfcGZu KCkgcGFnZSBwaW4gaXMKPiAtCQkgKiB1c2Vyc3BhY2UtY29udHJvbGxlZC4gSW4gdGhlIGZzLWRh eCBjYXNlIHRoaXMgY291bGQKPiAtCQkgKiBsZWFkIHRvIGluZGVmaW5pdGUgc3RhbGxzIGluIGZp bGVzeXN0ZW0gb3BlcmF0aW9ucy4KPiAtCQkgKiBEaXNhbGxvdyBhdHRlbXB0cyB0byBwaW4gZnMt ZGF4IHBhZ2VzIHZpYSB0aGlzCj4gLQkJICogaW50ZXJmYWNlLgo+IC0JCSAqLwo+IC0JCWlmIChy ZXQgPiAwICYmIHZtYV9pc19mc2RheCh2bWFzWzBdKSkgewo+IC0JCQlyZXQgPSAtRU9QTk9UU1VQ UDsKPiAtCQkJcHV0X3BhZ2UocGFnZVswXSk7Cj4gLQkJfQo+ICsJcmV0ID0gZ2V0X3VzZXJfcGFn ZXNfcmVtb3RlKE5VTEwsIG1tLCB2YWRkciwgMSwgZmxhZ3MgfCBGT0xMX0xPTkdURVJNLAo+ICsJ CQkJICAgIHBhZ2UsIHZtYXMsIE5VTEwpOwo+ICsJLyoKPiArCSAqIFRoZSBsaWZldGltZSBvZiBh IHZhZGRyX2dldF9wZm4oKSBwYWdlIHBpbiBpcwo+ICsJICogdXNlcnNwYWNlLWNvbnRyb2xsZWQu IEluIHRoZSBmcy1kYXggY2FzZSB0aGlzIGNvdWxkCj4gKwkgKiBsZWFkIHRvIGluZGVmaW5pdGUg c3RhbGxzIGluIGZpbGVzeXN0ZW0gb3BlcmF0aW9ucy4KPiArCSAqIERpc2FsbG93IGF0dGVtcHRz IHRvIHBpbiBmcy1kYXggcGFnZXMgdmlhIHRoaXMKPiArCSAqIGludGVyZmFjZS4KPiArCSAqLwo+ ICsJaWYgKHJldCA+IDAgJiYgdm1hX2lzX2ZzZGF4KHZtYXNbMF0pKSB7Cj4gKwkJcmV0ID0gLUVP UE5PVFNVUFA7Cj4gKwkJcHV0X3BhZ2UocGFnZVswXSk7Cj4gIAl9CgpBRkFJSyB0aGlzIGNodW5r IGlzIHJlZHVuZGFudCBub3cgYXMgaXQgaXMgc29tZSBoYWNrIHRvIGVtdWxhdGUKRk9MTF9MT05H VEVSTT8gU28gdm1hcyBjYW4gYmUgZGVsZXRlZCB0b28uCgpBbHNvIHVuY2xlYXIgd2h5IHRoaXMg ZnVuY3Rpb24gaGFzIHRoaXM6CgogICAgICAgIHVwX3JlYWQoJm1tLT5tbWFwX3NlbSk7CgogICAg ICAgIGlmIChyZXQgPT0gMSkgewogICAgICAgICAgICAgICAgKnBmbiA9IHBhZ2VfdG9fcGZuKHBh Z2VbMF0pOwogICAgICAgICAgICAgICAgcmV0dXJuIDA7CiAgICAgICAgfQoKICAgICAgICBkb3du X3JlYWQoJm1tLT5tbWFwX3NlbSk7CgpKYXNvbgpfX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fXwpkcmktZGV2ZWwgbWFpbGluZyBsaXN0CmRyaS1kZXZlbEBsaXN0 cy5mcmVlZGVza3RvcC5vcmcKaHR0cHM6Ly9saXN0cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9s aXN0aW5mby9kcmktZGV2ZWw=