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 06C33C433FE for ; Mon, 28 Nov 2022 08:26:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230176AbiK1I0S (ORCPT ); Mon, 28 Nov 2022 03:26:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39760 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229939AbiK1I0Q (ORCPT ); Mon, 28 Nov 2022 03:26:16 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 78EC2C07; Mon, 28 Nov 2022 00:26:15 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 31BB0B80B8E; Mon, 28 Nov 2022 08:26:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75F8BC433D6; Mon, 28 Nov 2022 08:26:05 +0000 (UTC) Message-ID: <0a52ed02-cf9d-eb67-8d68-e3d9dbe4e7b2@xs4all.nl> Date: Mon, 28 Nov 2022 09:26:04 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [PATCH mm-unstable v1 16/20] mm/frame-vector: remove FOLL_FORCE usage Content-Language: en-US To: David Hildenbrand , linux-kernel@vger.kernel.org, Andrew Morton Cc: x86@kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-samsung-soc@vger.kernel.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-perf-users@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kselftest@vger.kernel.org, Linus Torvalds , Jason Gunthorpe , John Hubbard , Peter Xu , Greg Kroah-Hartman , Andrea Arcangeli , Hugh Dickins , Nadav Amit , Vlastimil Babka , Matthew Wilcox , Mike Kravetz , Muchun Song , Shuah Khan , Lucas Stach , David Airlie , Oded Gabbay , Arnd Bergmann , Christoph Hellwig , Alex Williamson , Marek Szyprowski , Tomasz Figa , Mauro Carvalho Chehab References: <20221116102659.70287-1-david@redhat.com> <20221116102659.70287-17-david@redhat.com> <81fb0fa3-2e06-b765-56ac-a7d981194e59@redhat.com> <08b65ac6-6786-1080-18f8-d2be109c85fc@xs4all.nl> <9d0bf98a-3d6a-1082-e992-1338e1525935@redhat.com> From: Hans Verkuil In-Reply-To: <9d0bf98a-3d6a-1082-e992-1338e1525935@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On 28/11/2022 09:18, David Hildenbrand wrote: > On 28.11.22 09:17, Hans Verkuil wrote: >> Hi David, >> >> On 27/11/2022 11:35, David Hildenbrand wrote: >>> On 16.11.22 11:26, David Hildenbrand wrote: >>>> FOLL_FORCE is really only for ptrace access. According to commit >>>> 707947247e95 ("media: videobuf2-vmalloc: get_userptr: buffers are always >>>> writable"), get_vaddr_frames() currently pins all pages writable as a >>>> workaround for issues with read-only buffers. >>>> >>>> FOLL_FORCE, however, seems to be a legacy leftover as it predates >>>> commit 707947247e95 ("media: videobuf2-vmalloc: get_userptr: buffers are >>>> always writable"). Let's just remove it. >>>> >>>> Once the read-only buffer issue has been resolved, FOLL_WRITE could >>>> again be set depending on the DMA direction. >>>> >>>> Cc: Hans Verkuil >>>> Cc: Marek Szyprowski >>>> Cc: Tomasz Figa >>>> Cc: Marek Szyprowski >>>> Cc: Mauro Carvalho Chehab >>>> Signed-off-by: David Hildenbrand >>>> --- >>>>    drivers/media/common/videobuf2/frame_vector.c | 2 +- >>>>    1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/media/common/videobuf2/frame_vector.c b/drivers/media/common/videobuf2/frame_vector.c >>>> index 542dde9d2609..062e98148c53 100644 >>>> --- a/drivers/media/common/videobuf2/frame_vector.c >>>> +++ b/drivers/media/common/videobuf2/frame_vector.c >>>> @@ -50,7 +50,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, >>>>        start = untagged_addr(start); >>>>          ret = pin_user_pages_fast(start, nr_frames, >>>> -                  FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM, >>>> +                  FOLL_WRITE | FOLL_LONGTERM, >>>>                      (struct page **)(vec->ptrs)); >>>>        if (ret > 0) { >>>>            vec->got_ref = true; >>> >>> >>> Hi Andrew, >>> >>> see the discussion at [1] regarding a conflict and how to proceed with >>> upstreaming. The conflict would be easy to resolve, however, also >>> the patch description doesn't make sense anymore with [1]. >> >> Might it be easier and less confusing if you post a v2 of this series >> with my patch first? That way it is clear that 1) my patch has to come >> first, and 2) that it is part of a single series and should be merged >> by the mm subsystem. >> >> Less chances of things going wrong that way. >> >> Just mention in the v2 cover letter that the first patch was added to >> make it easy to backport that fix without being hampered by merge >> conflicts if it was added after your frame_vector.c patch. > > Yes, that's the way I would naturally do, it, however, Andrew prefers delta updates for minor changes. > > @Andrew, whatever you prefer! Andrew, I've resent my patch, this time with you CCed as well. Regards, Hans > > Thanks! >