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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 62FE2FC6171 for ; Thu, 13 Sep 2018 17:35:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D5E2B20854 for ; Thu, 13 Sep 2018 16:26:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D5E2B20854 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=deltatee.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727592AbeIMVgQ (ORCPT ); Thu, 13 Sep 2018 17:36:16 -0400 Received: from ale.deltatee.com ([207.54.116.67]:44350 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726452AbeIMVgQ (ORCPT ); Thu, 13 Sep 2018 17:36:16 -0400 Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtp (Exim 4.89) (envelope-from ) id 1g0URM-0001O7-NI; Thu, 13 Sep 2018 10:26:02 -0600 To: Dan Williams , akpm@linux-foundation.org Cc: Michal Hocko , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Christoph Hellwig , alexander.h.duyck@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <153680531988.453305.8080706591516037706.stgit@dwillia2-desk3.amr.corp.intel.com> <153680532635.453305.11297363695024516117.stgit@dwillia2-desk3.amr.corp.intel.com> From: Logan Gunthorpe Message-ID: Date: Thu, 13 Sep 2018 10:25:58 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <153680532635.453305.11297363695024516117.stgit@dwillia2-desk3.amr.corp.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, alexander.h.duyck@intel.com, hch@lst.de, jglisse@redhat.com, mhocko@suse.com, akpm@linux-foundation.org, dan.j.williams@intel.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v5 1/7] mm, devm_memremap_pages: Mark devm_memremap_pages() EXPORT_SYMBOL_GPL X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/09/18 08:22 PM, Dan Williams wrote: > devm_memremap_pages() is a facility that can create struct page entries > for any arbitrary range and give drivers the ability to subvert core > aspects of page management. > > Specifically the facility is tightly integrated with the kernel's memory > hotplug functionality. It injects an altmap argument deep into the > architecture specific vmemmap implementation to allow allocating from > specific reserved pages, and it has Linux specific assumptions about > page structure reference counting relative to get_user_pages() and > get_user_pages_fast(). It was an oversight and a mistake that this was > not marked EXPORT_SYMBOL_GPL from the outset. > > Again, devm_memremap_pagex() exposes and relies upon core kernel > internal assumptions and will continue to evolve along with 'struct > page', memory hotplug, and support for new memory types / topologies. > Only an in-kernel GPL-only driver is expected to keep up with this > ongoing evolution. This interface, and functionality derived from this > interface, is not suitable for kernel-external drivers. > > Cc: Michal Hocko > Cc: "Jérôme Glisse" > Reviewed-by: Christoph Hellwig > Signed-off-by: Dan Williams Reviewed-by: Logan Gunthorpe Mostly to say that I agree with you and Christoph on this debate and that the change to GPL does not affect my P2PDMA work. Logan