From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@kernel.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
Received: from vger.kernel.org (vger.kernel.org [23.128.96.18])
	by smtp.lore.kernel.org (Postfix) with ESMTP id 4E312CCA47F
	for <linux-kernel@archiver.kernel.org>; Tue,  5 Jul 2022 16:50:49 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S233143AbiGEQur (ORCPT <rfc822;linux-kernel@archiver.kernel.org>);
        Tue, 5 Jul 2022 12:50:47 -0400
Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45202 "EHLO
        lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S230264AbiGEQup (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 5 Jul 2022 12:50:45 -0400
Received: from verein.lst.de (verein.lst.de [213.95.11.211])
        by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E11BB1DA7E;
        Tue,  5 Jul 2022 09:50:44 -0700 (PDT)
Received: by verein.lst.de (Postfix, from userid 2407)
        id C89A168AA6; Tue,  5 Jul 2022 18:50:39 +0200 (CEST)
Date:   Tue, 5 Jul 2022 18:50:39 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Logan Gunthorpe <logang@deltatee.com>
Cc:     Christoph Hellwig <hch@lst.de>, Jason Gunthorpe <jgg@ziepe.ca>,
        linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
        linux-block@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-mm@kvack.org, iommu@lists.linux-foundation.org,
        Stephen Bates <sbates@raithlin.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Christian =?iso-8859-1?Q?K=F6nig?= <christian.koenig@amd.com>,
        John Hubbard <jhubbard@nvidia.com>,
        Don Dutile <ddutile@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Minturn Dave B <dave.b.minturn@intel.com>,
        Jason Ekstrand <jason@jlekstrand.net>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Xiong Jianxin <jianxin.xiong@intel.com>,
        Bjorn Helgaas <helgaas@kernel.org>,
        Ira Weiny <ira.weiny@intel.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Martin Oliveira <martin.oliveira@eideticom.com>,
        Chaitanya Kulkarni <ckulkarnilinux@gmail.com>,
        Ralph Campbell <rcampbell@nvidia.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v7 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem()
Message-ID: <20220705165039.GB14566@lst.de>
References: <20220615161233.17527-21-logang@deltatee.com> <20220629064854.GD17576@lst.de> <99242789-66a6-bbd2-b56a-e47891f4522e@deltatee.com> <20220629175906.GU23621@ziepe.ca> <20220705075108.GB17451@lst.de> <20220705135102.GE23621@ziepe.ca> <20220705161240.GB13721@lst.de> <a509b13c-244b-23fc-f989-339750a733a5@deltatee.com> <20220705164315.GB14484@lst.de> <acb91f37-0470-8ce4-19e4-426903cbc3a1@deltatee.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <acb91f37-0470-8ce4-19e4-426903cbc3a1@deltatee.com>
User-Agent: Mutt/1.5.17 (2007-11-01)
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

[note for the newcomers, this is about allowing mmap()ing the PCIe
P2P memory from the generic PCI P2P code through sysfs, and more
importantly how to revoke it on device removal]

On Tue, Jul 05, 2022 at 10:44:49AM -0600, Logan Gunthorpe wrote:
> We might be able to. I'm not sure. I'll have to figure out how to find
> that inode from the p2pdma code. I haven't found an obvious interface to
> do that.

I think the right way to approach this would be a new sysfs API
that internally calls unmap_mapping_range internally instead of
exposing the inode. I suspect that might actually be the right thing
to do for iomem_inode as well.