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 7CBB5C4332F for ; Wed, 23 Nov 2022 13:17:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 079BF6B0071; Wed, 23 Nov 2022 08:17:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 002AB6B0073; Wed, 23 Nov 2022 08:17:45 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DE51A6B0074; Wed, 23 Nov 2022 08:17:45 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id CC21D6B0071 for ; Wed, 23 Nov 2022 08:17:45 -0500 (EST) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 956F4AB19D for ; Wed, 23 Nov 2022 13:17:45 +0000 (UTC) X-FDA: 80164759290.19.D74AD8A Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf08.hostedemail.com (Postfix) with ESMTP id 0D3AE16000B for ; Wed, 23 Nov 2022 13:17:44 +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 0D2BB61CAD; Wed, 23 Nov 2022 13:17:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC3BFC433D6; Wed, 23 Nov 2022 13:17:36 +0000 (UTC) Message-ID: <73481668-9c41-7d01-d328-bd137a57c0b3@xs4all.nl> Date: Wed, 23 Nov 2022 14:17:35 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 Subject: Re: [PATCH mm-unstable v1 13/20] media: videobuf-dma-sg: remove FOLL_FORCE usage Content-Language: en-US To: David Hildenbrand , linux-kernel@vger.kernel.org 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 , Andrew Morton , 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 , Mauro Carvalho Chehab References: <20221116102659.70287-1-david@redhat.com> <20221116102659.70287-14-david@redhat.com> From: Hans Verkuil In-Reply-To: <20221116102659.70287-14-david@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1669209465; a=rsa-sha256; cv=none; b=ijilJ/8jA58uRYeVnezac1Un90ePMdAdCiKBlxEgqNLK8mTryt4gJ5gjlynp0WIg5fePZZ Nxle2hhCgnw3GFAhFPGm5sLt4UgsTDy+qhwE25RSnadP7kAPP7Fm3ndGmwxX/5c+kSzjK/ ZInBIWgue8FVinejzZ05CODppmocu0Q= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=xs4all.nl (policy=none); spf=pass (imf08.hostedemail.com: domain of "SRS0=+b1z=3X=xs4all.nl=hverkuil@kernel.org" designates 139.178.84.217 as permitted sender) smtp.mailfrom="SRS0=+b1z=3X=xs4all.nl=hverkuil@kernel.org" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1669209465; 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=JzBAHGiYGonhKt624puQu+Q7dXE0IseQBohJYpzV3iw=; b=sn0G2sy/c2vsAuzKA4w/0IZfZTk0ZvKINlRDdL84IwcbG8xYORMKY2aPr+mcF7FXYm6/aG arOL/IbxUM7WkOnxU0AjKVnRdjx8+F0vRqiKNIa2qo1EiHRIxzqK19qD4Zy5+QnbWO/zPz +mxB9VdpPFCQL7U1Y9A+QTt8owWmF14= X-Rspam-User: X-Rspamd-Queue-Id: 0D3AE16000B Authentication-Results: imf08.hostedemail.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=xs4all.nl (policy=none); spf=pass (imf08.hostedemail.com: domain of "SRS0=+b1z=3X=xs4all.nl=hverkuil@kernel.org" designates 139.178.84.217 as permitted sender) smtp.mailfrom="SRS0=+b1z=3X=xs4all.nl=hverkuil@kernel.org" X-Stat-Signature: 4yewzmuifbt4fqf74ztjpttfnrian96j X-Rspamd-Server: rspam10 X-HE-Tag: 1669209464-972923 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 16/11/2022 11:26, David Hildenbrand wrote: > GUP now supports reliable R/O long-term pinning in COW mappings, such > that we break COW early. MAP_SHARED VMAs only use the shared zeropage so > far in one corner case (DAXFS file with holes), which can be ignored > because GUP does not support long-term pinning in fsdax (see > check_vma_flags()). > > Consequently, FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM is no longer required > for reliable R/O long-term pinning: FOLL_LONGTERM is sufficient. So stop > using FOLL_FORCE, which is really only for ptrace access. > > Cc: Mauro Carvalho Chehab > Signed-off-by: David Hildenbrand Acked-by: Hans Verkuil Looks good! Hans > --- > drivers/media/v4l2-core/videobuf-dma-sg.c | 14 +++++--------- > 1 file changed, 5 insertions(+), 9 deletions(-) > > diff --git a/drivers/media/v4l2-core/videobuf-dma-sg.c b/drivers/media/v4l2-core/videobuf-dma-sg.c > index f75e5eedeee0..234e9f647c96 100644 > --- a/drivers/media/v4l2-core/videobuf-dma-sg.c > +++ b/drivers/media/v4l2-core/videobuf-dma-sg.c > @@ -151,17 +151,16 @@ static void videobuf_dma_init(struct videobuf_dmabuf *dma) > static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma, > int direction, unsigned long data, unsigned long size) > { > + unsigned int gup_flags = FOLL_LONGTERM; > unsigned long first, last; > - int err, rw = 0; > - unsigned int flags = FOLL_FORCE; > + int err; > > dma->direction = direction; > switch (dma->direction) { > case DMA_FROM_DEVICE: > - rw = READ; > + gup_flags |= FOLL_WRITE; > break; > case DMA_TO_DEVICE: > - rw = WRITE; > break; > default: > BUG(); > @@ -177,14 +176,11 @@ static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma, > if (NULL == dma->pages) > return -ENOMEM; > > - if (rw == READ) > - flags |= FOLL_WRITE; > - > dprintk(1, "init user [0x%lx+0x%lx => %lu pages]\n", > data, size, dma->nr_pages); > > - err = pin_user_pages(data & PAGE_MASK, dma->nr_pages, > - flags | FOLL_LONGTERM, dma->pages, NULL); > + err = pin_user_pages(data & PAGE_MASK, dma->nr_pages, gup_flags, > + dma->pages, NULL); > > if (err != dma->nr_pages) { > dma->nr_pages = (err >= 0) ? err : 0;