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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 4DBE6C433E0 for ; Fri, 29 May 2020 09:11:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 26AED207D4 for ; Fri, 29 May 2020 09:11:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iZiECxNQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726415AbgE2JL2 (ORCPT ); Fri, 29 May 2020 05:11:28 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:27106 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725710AbgE2JL1 (ORCPT ); Fri, 29 May 2020 05:11:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1590743485; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=kQQnvDWn5mXH5MNoGWFpZNnT+ceYiOOMeyMBuYfOO8s=; b=iZiECxNQcVSS+uo9EjTM49j0J2D+wRw06oJzXst8fDFUvbTZztZ1ArSqy7o/ITVOzhGDEH 4dahDaKFG7m4Vo7oap7kWKvSZ63njA1eh035nIkENrtLkt7hV+P5lZQyRJbc9L0S8cqvDw hO1MtQ3/Tv34sa5PLAvJGprUDNyMgzA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-461-L1ShakoDNqqP3wd32Ivpbg-1; Fri, 29 May 2020 05:11:23 -0400 X-MC-Unique: L1ShakoDNqqP3wd32Ivpbg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 90656800688; Fri, 29 May 2020 09:11:21 +0000 (UTC) Received: from [10.36.114.91] (ovpn-114-91.ams2.redhat.com [10.36.114.91]) by smtp.corp.redhat.com (Postfix) with ESMTP id B26E510098AB; Fri, 29 May 2020 09:11:19 +0000 (UTC) Subject: Re: [PATCH] mm/gup: documentation fix for pin_user_pages*() APIs To: John Hubbard , Andrew Morton Cc: Souptick Joarder , LKML , linux-mm@kvack.org, Dan Carpenter , Jan Kara , Vlastimil Babka References: <20200529084515.46259-1-jhubbard@nvidia.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: <37811e3c-cf0c-eb52-0365-7980a9c0f334@redhat.com> Date: Fri, 29 May 2020 11:11:18 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200529084515.46259-1-jhubbard@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29.05.20 10:45, John Hubbard wrote: > All of the pin_user_pages*() API calls will cause pages to be > dma-pinned. As such, they are all suitable for either DMA, RDMA, > and/or Direct IO. The documentation should say so, but it was > instead saying that three of the API calls were only suitable for > Direct IO. This was discovered when a reviewer wondered why an > API call that specifically recommended against Case 2 (DMA/RDMA) > was being used in a DMA situation [1]. > > Fix this by simply deleting those claims. The gup.c comments already > refer to the more extensive Documentation/core-api/pin_user_pages.rst, > which does have the correct guidance. So let's just write it once, > there. > > [1] https://lore.kernel.org/r/20200529074658.GM30374@kadam > > Cc: Dan Carpenter > Cc: Jan Kara > Cc: Vlastimil Babka > Signed-off-by: John Hubbard > --- > > Hi, > > This applies on top of linux-next, in order to avoid a conflict with > Mauro Carvalho Chehab's fix to the lines right above these. > > thanks, > John Hubbard > NVIDIA > > > mm/gup.c | 9 --------- > 1 file changed, 9 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index ee039d421746d..311d0f11b35e6 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -2875,9 +2875,6 @@ EXPORT_SYMBOL_GPL(get_user_pages_fast); > * > * FOLL_PIN means that the pages must be released via unpin_user_page(). Please > * see Documentation/core-api/pin_user_pages.rst for further details. > - * > - * This is intended for Case 1 (DIO) in Documentation/core-api/pin_user_pages.rst. It > - * is NOT intended for Case 2 (RDMA: long-term pins). > */ > int pin_user_pages_fast(unsigned long start, int nr_pages, > unsigned int gup_flags, struct page **pages) > @@ -2951,9 +2948,6 @@ EXPORT_SYMBOL_GPL(pin_user_pages_fast_only); > * > * FOLL_PIN means that the pages must be released via unpin_user_page(). Please > * see Documentation/core-api/pin_user_pages.rst for details. > - * > - * This is intended for Case 1 (DIO) in Documentation/core-api/pin_user_pages.rst. It > - * is NOT intended for Case 2 (RDMA: long-term pins). > */ > long pin_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm, > unsigned long start, unsigned long nr_pages, > @@ -2987,9 +2981,6 @@ EXPORT_SYMBOL(pin_user_pages_remote); > * > * FOLL_PIN means that the pages must be released via unpin_user_page(). Please > * see Documentation/core-api/pin_user_pages.rst for details. > - * > - * This is intended for Case 1 (DIO) in Documentation/core-api/pin_user_pages.rst. It > - * is NOT intended for Case 2 (RDMA: long-term pins). > */ > long pin_user_pages(unsigned long start, unsigned long nr_pages, > unsigned int gup_flags, struct page **pages, > Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb