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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60A59C433EF for ; Wed, 29 Jun 2022 16:00:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234440AbiF2QAl (ORCPT ); Wed, 29 Jun 2022 12:00:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234239AbiF2QAQ (ORCPT ); Wed, 29 Jun 2022 12:00:16 -0400 Received: from ale.deltatee.com (ale.deltatee.com [204.191.154.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B58B11E3C1; Wed, 29 Jun 2022 09:00:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:In-Reply-To:From:References:Cc:To: MIME-Version:Date:Message-ID:content-disposition; bh=DB/o3OL3a8p7Pc5UauzdC49YqSJaVUxyZzB2ozvl7YI=; b=iZsQhnlbpW9sXN/GJaS3jAMw+w 8mn6izIwy085ybj1EKwF9DeEsOt9qyrlLxTvp+P9EVdEEjbQUwL5dVFTMDhjOaBp5PaGks7Gp0vTL Pz4wv3iQN06W33bmzngimPEHWIwXW/s9XuLr428TJq/t9Jpay97zThl6gUaoJoo9UCQ2zqUNOyzir HCs15GX4eR/A0kDWtJ7SaGXsATfCWkaQvG0flWXjWzNvEQkpGnbcu6afAc4ry10M/XvkH8tpuj6H7 pV0F7DMjJNZAL9ALRpJtO4Tl1f8+YWZ+iaFmr74pOp+DJyj7fvd7YDPPvJ3gnFshVDAC+8VlO6cQM jCOY9fhQ==; Received: from s0106a84e3fe8c3f3.cg.shawcable.net ([24.64.144.200] helo=[192.168.0.10]) by ale.deltatee.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1o6a6s-002RzJ-UG; Wed, 29 Jun 2022 10:00:11 -0600 Message-ID: <99242789-66a6-bbd2-b56a-e47891f4522e@deltatee.com> Date: Wed, 29 Jun 2022 10:00:09 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Content-Language: en-CA To: Christoph Hellwig Cc: 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 , Dan Williams , Jason Gunthorpe , =?UTF-8?Q?Christian_K=c3=b6nig?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni , Ralph Campbell , Bjorn Helgaas References: <20220615161233.17527-1-logang@deltatee.com> <20220615161233.17527-21-logang@deltatee.com> <20220629064854.GD17576@lst.de> From: Logan Gunthorpe In-Reply-To: <20220629064854.GD17576@lst.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 24.64.144.200 X-SA-Exim-Rcpt-To: hch@lst.de, 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, sbates@raithlin.com, dan.j.williams@intel.com, jgg@ziepe.ca, christian.koenig@amd.com, jhubbard@nvidia.com, ddutile@redhat.com, willy@infradead.org, daniel.vetter@ffwll.ch, dave.b.minturn@intel.com, jason@jlekstrand.net, dave.hansen@linux.intel.com, jianxin.xiong@intel.com, helgaas@kernel.org, ira.weiny@intel.com, robin.murphy@arm.com, martin.oliveira@eideticom.com, ckulkarnilinux@gmail.com, rcampbell@nvidia.com, bhelgaas@google.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v7 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem() X-SA-Exim-Version: 4.2.1 (built Sat, 13 Feb 2021 17:57:42 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022-06-29 00:48, Christoph Hellwig wrote: > On Wed, Jun 15, 2022 at 10:12:32AM -0600, Logan Gunthorpe wrote: >> A pseudo mount is used to allocate an inode for each PCI device. The >> inode's address_space is used in the file doing the mmap so that all >> VMAs are collected and can be unmapped if the PCI device is unbound. >> After unmapping, the VMAs are iterated through and their pages are >> put so the device can continue to be unbound. An active flag is used >> to signal to VMAs not to allocate any further P2P memory once the >> removal process starts. The flag is synchronized with concurrent >> access with an RCU lock. > > Can't we come up with a way of doing this without all the pseudo-fs > garbagage? I really hate all the overhead for that in the next > nvme patch as well. I assume you still want to be able to unmap the VMAs on unbind and not just hang? I'll see if I can come up with something to do the a similar thing using vm_private data or some such. I was not a fan of the extra code for this either, but I was given to understand that it was the standard way to collect and cleanup VMAs. Thanks for the reviews, Logan