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 ACC33C433F5 for ; Tue, 21 Dec 2021 17:27:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233588AbhLUR1e (ORCPT ); Tue, 21 Dec 2021 12:27:34 -0500 Received: from ale.deltatee.com ([204.191.154.188]:53664 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229925AbhLUR1d (ORCPT ); Tue, 21 Dec 2021 12:27:33 -0500 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=tHUZjlzEP3lopTOQQN8mNVWiWWJwS29dSxMFB9HD+A8=; b=BGAK1lUDvyuZ48bEqcCgg4po+X NmanPhpAS6+UNAz03pYcDzNhaFu6mxvVL+qqnx53zeLQX6h1PxLDsBp8IULQlncbyQRvfjX79PRX9 gvGf08CiKgzW2Sj7hkGZNGAo4+HMl1MGmxNHvizb/NiE6kQd8yfGXJ/3dXLgtk53IKoxY4ZDedsfU DPyaBVJpdtBflN4LZlAsXbgLCmRJRoBDGMAfmDRTKiT01PhljpgcRRK1n7m1/kODICqJNT8gQZlWb 9hO76EMgdAOZiU3xTp4NH/AWvbL4YKf/4o7K7oRm5tr5TSQHxlKuC+ozusnGeek8c5BYNcduFKMx3 t6BHI/9w==; Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1mziuv-00AX3M-08; Tue, 21 Dec 2021 10:27:14 -0700 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 , Jakowski Andrzej , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni References: <20211117215410.3695-1-logang@deltatee.com> <20211117215410.3695-22-logang@deltatee.com> <20211221090648.GE7949@lst.de> From: Logan Gunthorpe Message-ID: <369770be-c2d1-fcbf-f317-279981707cb9@deltatee.com> Date: Tue, 21 Dec 2021 10:27:12 -0700 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: <20211221090648.GE7949@lst.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-CA Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 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, jgg@ziepe.ca, dan.j.williams@intel.com, 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, hch@lst.de X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v4 21/23] mm: use custom page_free for P2PDMA pages 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-pci@vger.kernel.org On 2021-12-21 2:06 a.m., Christoph Hellwig wrote: > On Wed, Nov 17, 2021 at 02:54:08PM -0700, Logan Gunthorpe wrote: >> When P2PDMA pages are passed to userspace, they will need to be >> reference counted properly and returned to their genalloc after their >> reference count returns to 1. This is accomplished with the existing >> DEV_PAGEMAP_OPS and the .page_free() operation. >> >> Change CONFIG_P2PDMA to select CONFIG_DEV_PAGEMAP_OPS and add >> MEMORY_DEVICE_PCI_P2PDMA to page_is_devmap_managed(), >> devmap_managed_enable_[put|get]() and free_devmap_managed_page(). > > Uuuh. We are trying hard to kill off this magic free at refcount 1 > behavior in the amdgpu device coherent series. We really should not > add more of this. Ah, ok. I found Ralph's patch that cleans this up and I can try to rebase this onto it for future postings until it gets merged. Your other comments I can address for the next time I post this series. Thanks for the review! Logan