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=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=unavailable 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 CD9B9C433E7 for ; Sat, 10 Oct 2020 22:15:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 957BC20795 for ; Sat, 10 Oct 2020 22:15:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602368158; bh=/M97QDk4dmePHLGMz8L/1LDgfweGz0LFfE/UcKJE7Us=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=t8LluzTGEGxMIGv6tu3Ovzzw50YgdzzXxTjYkoiq0XW7ovSQQGDIMmGDvmWTRdUZf G5hP9jk9JerR1pHXHvalo94jW5VvK8+23bYpBD0r+26un7uX1XXJfI+6WxLAmQYH9L /fwejJTDg/GIqJWVijK2FuoTYyRsRhLuXsFcOgPE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729668AbgJJVxF (ORCPT ); Sat, 10 Oct 2020 17:53:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:56966 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731025AbgJJTxO (ORCPT ); Sat, 10 Oct 2020 15:53:14 -0400 Received: from coco.lan (ip5f5ad5ce.dynamic.kabel-deutschland.de [95.90.213.206]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9E166207CD; Sat, 10 Oct 2020 09:24:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602321866; bh=/M97QDk4dmePHLGMz8L/1LDgfweGz0LFfE/UcKJE7Us=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=0WfcGZ/NRaNLmDS+jOh+NTKZmtgBMPUVlTwtRgayCgG8fNqT9ga5dKdpSd17V6cdr HukrmYrFiRiZHk4mzgeyyRmliXyLjN62NnFMnyCvZOm9KoAKj1aPSNb/0Gk/GRwb/0 cnkcKxRZlgiEC0lyCm9ojQx8D9uJxVDmS5Ffiehg= Date: Sat, 10 Oct 2020 11:24:16 +0200 From: Mauro Carvalho Chehab To: Daniel Vetter , Linus Torvalds Cc: DRI Development , LKML , kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, linux-s390@vger.kernel.org, Daniel Vetter , Jason Gunthorpe , Kees Cook , Dan Williams , Andrew Morton , John Hubbard , =?UTF-8?B?SsOpcsO0bWU=?= Glisse , Jan Kara , Pawel Osciak , Marek Szyprowski , Kyungmin Park , Tomasz Figa , Laurent Dufour , Vlastimil Babka , Daniel Jordan , Michel Lespinasse Subject: Re: [PATCH v2 10/17] media/videbuf1|2: Mark follow_pfn usage as unsafe Message-ID: <20201010112416.4259249a@coco.lan> In-Reply-To: <20201009075934.3509076-11-daniel.vetter@ffwll.ch> References: <20201009075934.3509076-1-daniel.vetter@ffwll.ch> <20201009075934.3509076-11-daniel.vetter@ffwll.ch> X-Mailer: Claws Mail 3.17.6 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Em Fri, 9 Oct 2020 09:59:27 +0200 Daniel Vetter escreveu: > The media model assumes that buffers are all preallocated, so that > when a media pipeline is running we never miss a deadline because the > buffers aren't allocated or available. >=20 > This means we cannot fix the v4l follow_pfn usage through > mmu_notifier, without breaking how this all works. The only real fix > is to deprecate userptr support for VM_IO | VM_PFNMAP mappings and > tell everyone to cut over to dma-buf memory sharing for zerocopy. >=20 > userptr for normal memory will keep working as-is. I won't repeat here the discussions for patch 09/17, but just to be clear about this one: NACK. We need a better alternative to avoid breaking existing media applications. >=20 > Signed-off-by: Daniel Vetter > Cc: Jason Gunthorpe > Cc: Kees Cook > Cc: Dan Williams > Cc: Andrew Morton > Cc: John Hubbard > Cc: J=C3=A9r=C3=B4me Glisse > Cc: Jan Kara > Cc: Dan Williams > Cc: linux-mm@kvack.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-samsung-soc@vger.kernel.org > Cc: linux-media@vger.kernel.org > Cc: Pawel Osciak > Cc: Marek Szyprowski > Cc: Kyungmin Park > Cc: Tomasz Figa > Cc: Laurent Dufour > Cc: Vlastimil Babka > Cc: Daniel Jordan > Cc: Michel Lespinasse > --- > drivers/media/common/videobuf2/frame_vector.c | 2 +- > drivers/media/v4l2-core/videobuf-dma-contig.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) >=20 > diff --git a/drivers/media/common/videobuf2/frame_vector.c b/drivers/medi= a/common/videobuf2/frame_vector.c > index 2b0b97761d15..a1b85fe9e7c1 100644 > --- a/drivers/media/common/videobuf2/frame_vector.c > +++ b/drivers/media/common/videobuf2/frame_vector.c > @@ -69,7 +69,7 @@ int get_vaddr_frames(unsigned long start, unsigned int = nr_frames, > break; > =20 > while (ret < nr_frames && start + PAGE_SIZE <=3D vma->vm_end) { > - err =3D follow_pfn(vma, start, &nums[ret]); > + err =3D unsafe_follow_pfn(vma, start, &nums[ret]); > if (err) { > if (ret =3D=3D 0) > ret =3D err; > diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c b/drivers/medi= a/v4l2-core/videobuf-dma-contig.c > index 52312ce2ba05..821c4a76ab96 100644 > --- a/drivers/media/v4l2-core/videobuf-dma-contig.c > +++ b/drivers/media/v4l2-core/videobuf-dma-contig.c > @@ -183,7 +183,7 @@ static int videobuf_dma_contig_user_get(struct videob= uf_dma_contig_memory *mem, > user_address =3D untagged_baddr; > =20 > while (pages_done < (mem->size >> PAGE_SHIFT)) { > - ret =3D follow_pfn(vma, user_address, &this_pfn); > + ret =3D unsafe_follow_pfn(vma, user_address, &this_pfn); > if (ret) > break; > =20 Thanks, Mauro