From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f71.google.com (mail-pl0-f71.google.com [209.85.160.71]) by kanga.kvack.org (Postfix) with ESMTP id 3696B6B0007 for ; Mon, 9 Jul 2018 20:34:20 -0400 (EDT) Received: by mail-pl0-f71.google.com with SMTP id y7-v6so11092380plt.17 for ; Mon, 09 Jul 2018 17:34:20 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id h66-v6si16992591pfa.238.2018.07.09.17.34.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 09 Jul 2018 17:34:18 -0700 (PDT) Date: Mon, 9 Jul 2018 17:34:17 -0700 From: Andrew Morton Subject: Re: [PATCH v3 7/8] mm, hmm: Mark hmm_devmem_{add, add_resource} EXPORT_SYMBOL_GPL Message-Id: <20180709173417.171c0d75ac3fd55b45881d3f@linux-foundation.org> In-Reply-To: References: <152938827880.17797.439879736804291936.stgit@dwillia2-desk3.amr.corp.intel.com> <152938831573.17797.15264540938029137916.stgit@dwillia2-desk3.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams Cc: =?ISO-8859-1?Q?J=E9r=F4me?= Glisse , Logan Gunthorpe , Christoph Hellwig , Linux MM , Linux Kernel Mailing List On Fri, 6 Jul 2018 16:53:11 -0700 Dan Williams w= rote: > On Mon, Jun 18, 2018 at 11:05 PM, Dan Williams = wrote: > > The routines hmm_devmem_add(), and hmm_devmem_add_resource() are > > now wrappers around the functionality provided by devm_memremap_pages()= to > > inject a dev_pagemap instance and hook page-idle events. The > > devm_memremap_pages() interface is base infrastructure for HMM which has > > more and deeper ties into the kernel memory management implementation > > than base ZONE_DEVICE. > > > > Originally, the HMM page structure creation routines copied the > > devm_memremap_pages() code and reused ZONE_DEVICE. A cleanup to unify > > the implementations was discussed during the initial review: > > http://lkml.iu.edu/hypermail/linux/kernel/1701.2/00812.html > > > > Given that devm_memremap_pages() is marked EXPORT_SYMBOL_GPL by its > > authors and the hmm_devmem_{add,add_resource} routines are simple > > wrappers around that base, mark these routines as EXPORT_SYMBOL_GPL as > > well. > > > > Cc: "J=E9r=F4me Glisse" > > Cc: Logan Gunthorpe > > Reviewed-by: Christoph Hellwig > > Signed-off-by: Dan Williams >=20 > Currently OpenAFS is blocked from compiling with the 4.18 series due > to the current state of put_page() inadvertently pulling in GPL-only > symbols. This series, "PATCH v3 0/8] mm: Rework hmm to use > devm_memremap_pages and other fixes" corrects that situation and > corrects HMM's usage of EXPORT_SYMBOL_GPL. >=20 > If HMM wants to export functionality to out-of-tree proprietary > drivers it should do so without consuming GPL-only exports, or > consuming internal-only public functions in its exports. >=20 > In addition to duplicating devm_memremap_pages(), that should have > been EXPORT_SYMBOL_GPL from the beginning, it is also exporting / > consuming these GPL-only symbols via HMM's EXPORT_SYMBOL entry points. >=20 > mmu_notifier_unregister_no_release > percpu_ref > region_intersects > __class_create >=20 > Those entry points also consume / export functionality that is > currently not exported to any other driver. >=20 > alloc_pages_vma > walk_page_range >=20 > Andrew, please consider applying this v3 series to fix this up (let me > know if you need a resend). A resend would be good. And include the above info in the changelog. I can't say I'm terribly happy with the HMM situation. I was under the impression that a significant number of significant in-tree drivers would be using HMM but I've heard nothing since, apart from ongoing nouveau work, which will be perfectly happy with GPL-only exports. So yes, we should revisit the licensing situation and, if only nouveau will be using HMM we should revisit HMM's overall usefulness.