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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id CEA2BC4332F for ; Mon, 28 Nov 2022 08:26:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 433496B0072; Mon, 28 Nov 2022 03:26:15 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3E23F6B0073; Mon, 28 Nov 2022 03:26:15 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2A94A6B0074; Mon, 28 Nov 2022 03:26:15 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 1CE7A6B0072 for ; Mon, 28 Nov 2022 03:26:15 -0500 (EST) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id CC572C0768 for ; Mon, 28 Nov 2022 08:26:14 +0000 (UTC) X-FDA: 80182168668.16.6F30A68 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf24.hostedemail.com (Postfix) with ESMTP id 6BACB180017 for ; Mon, 28 Nov 2022 08:26:14 +0000 (UTC) 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 dfw.source.kernel.org (Postfix) with ESMTPS id 7A51260F9E; Mon, 28 Nov 2022 08:26:13 +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 ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=none; spf=pass (imf24.hostedemail.com: domain of "SRS0=T0lg=34=xs4all.nl=hverkuil@kernel.org" designates 139.178.84.217 as permitted sender) smtp.mailfrom="SRS0=T0lg=34=xs4all.nl=hverkuil@kernel.org"; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=xs4all.nl (policy=none) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1669623974; a=rsa-sha256; cv=none; b=QOEqPDtYNS1R7EqidotkRP5LRgk6bgPkGlaeRWvKMw1YYRE6GrLQcgL1TBGpURSIUyT/eU EyC6OXUrENONYCIw18lsUoyJSY2tsEffGG3y/ELJyF0OP9vDxCrdbUSz2uT0+2JBXvKphn iNv7LYnMGtTxtUqA4eQaHbc+RATBWQc= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1669623974; h=from:from:sender: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; bh=L50XODkTNXqAf+4faB05t9t7Gv9fDclqWcA2Q16mlaU=; b=J25c3aO5CUc73+SxNdqFTQ7OPHgyNm6nxev5cTlAhgHJQQ7Oa8h0zM4S1/M8gBVjjhOUCr RtUQQGX54Il1jRGW1ni6BTvaxCbQoDzsgbuk7l0Kd16I9zJ/pcy3jrrZ0mYyZuSN5AfMbY JpyRGZh45FWviYn9cIlnFj7PEeKzhoo= X-Stat-Signature: c9z5q9n8ys987q3zswfkiqes96zezigg X-Rspamd-Queue-Id: 6BACB180017 X-Rspam-User: X-Rspamd-Server: rspam04 Authentication-Results: imf24.hostedemail.com; dkim=none; spf=pass (imf24.hostedemail.com: domain of "SRS0=T0lg=34=xs4all.nl=hverkuil@kernel.org" designates 139.178.84.217 as permitted sender) smtp.mailfrom="SRS0=T0lg=34=xs4all.nl=hverkuil@kernel.org"; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=xs4all.nl (policy=none) X-HE-Tag: 1669623974-14382 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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! >