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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6756C433FE for ; Wed, 29 Sep 2021 21:47:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C7C8361501 for ; Wed, 29 Sep 2021 21:47:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234471AbhI2Vss (ORCPT ); Wed, 29 Sep 2021 17:48:48 -0400 Received: from ale.deltatee.com ([204.191.154.188]:59254 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233672AbhI2Vsr (ORCPT ); Wed, 29 Sep 2021 17:48:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:In-Reply-To:MIME-Version:Date: Message-ID:From:References:Cc:To:content-disposition; bh=E0+dWT8gAeYt6sxwFEz+vMLQHximHDqyya3XwSsMquA=; b=B1+ojUPj4nQ9gfTcjrhn2ItoGQ aINPbvBXV9Nds1L0hVw7x1w9p2f358U5Fu3wsB7LxIEcnVMidcZxVp9bnuYVbm+woQWShpT40RVzU OWcloGv5IVDL4LO1/uqKO7qJp8yyXESOWL5Pk908ezjO+8d79gGLYr04akWdskoQQITHB9DMMIHmA 92BxFHqUONXLFywx+DHgJ56IhJUbz68+CmbfX8Rw8Ao+P9/K4WRFREHY1Dgj8ZBtJ3HAi1EpCtHUm l5AU9JEaCtAhOL0zCRMIIQj6PRFACLBxlb8WUFdKUs9k94DRCRe5C1KpsFdiatomWcFHdJ3AjXAfr abJCdzRA==; Received: from s0106a84e3fe8c3f3.cg.shawcable.net ([24.64.144.200] helo=[192.168.0.10]) by ale.deltatee.com with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1mVhPY-0006ZO-78; Wed, 29 Sep 2021 15:46:45 -0600 To: Jason Gunthorpe 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 , Christoph Hellwig , Dan Williams , =?UTF-8?Q?Christian_K=c3=b6nig?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Jakowski Andrzej , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni References: <20210916234100.122368-1-logang@deltatee.com> <20210916234100.122368-20-logang@deltatee.com> <20210928200506.GX3544071@ziepe.ca> From: Logan Gunthorpe Message-ID: <3dfbfb6c-321c-f717-8adf-a37956f15678@deltatee.com> Date: Wed, 29 Sep 2021 15:46:40 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20210928200506.GX3544071@ziepe.ca> Content-Type: text/plain; charset=utf-8 Content-Language: en-CA Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 24.64.144.200 X-SA-Exim-Rcpt-To: ckulkarnilinux@gmail.com, martin.oliveira@eideticom.com, robin.murphy@arm.com, ira.weiny@intel.com, helgaas@kernel.org, jianxin.xiong@intel.com, dave.hansen@linux.intel.com, jason@jlekstrand.net, dave.b.minturn@intel.com, andrzej.jakowski@intel.com, daniel.vetter@ffwll.ch, willy@infradead.org, ddutile@redhat.com, jhubbard@nvidia.com, christian.koenig@amd.com, dan.j.williams@intel.com, hch@lst.de, sbates@raithlin.com, iommu@lists.linux-foundation.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, jgg@ziepe.ca X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v3 19/20] PCI/P2PDMA: introduce pci_mmap_p2pmem() X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2021-09-28 2:05 p.m., Jason Gunthorpe wrote: > On Thu, Sep 16, 2021 at 05:40:59PM -0600, Logan Gunthorpe wrote: > >> +static void pci_p2pdma_unmap_mappings(void *data) >> +{ >> + struct pci_dev *pdev = data; >> + struct pci_p2pdma *p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); >> + >> + p2pdma->active = false; >> + synchronize_rcu(); >> + unmap_mapping_range(p2pdma->inode->i_mapping, 0, 0, 1); >> + pci_p2pdma_free_mappings(p2pdma->inode->i_mapping); >> +} > > If this is going to rely on unmap_mapping_range then GUP should also > reject this memory for FOLL_LONGTERM.. Right, makes sense. > > What along this control flow: > >> + error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_unmap_mappings, >> + pdev); > > Waits for all the page refcounts to go to zero? That's already in the existing code as part of memunmap_pages() which puts the original reference to all the pages and then waits for the reference to go to zero. This new action unmaps all the VMAs so that the subsequent call to memunmap_pages() doesn't block on userspace processes. Logan