From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: Re: [PATCH mm-unstable v1 16/20] mm/frame-vector: remove FOLL_FORCE usage Date: Sun, 27 Nov 2022 11:35:09 +0100 Message-ID: <81fb0fa3-2e06-b765-56ac-a7d981194e59@redhat.com> References: <20221116102659.70287-1-david@redhat.com> <20221116102659.70287-17-david@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:Subject:From:References:Cc:To: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=G1LxGg6lThxykOMDsBO+gkd4mNaE+E0lcZrZBvY3ckQ=; b=aDz5WzCYsLrzzS tC2pC/WUtCjXxhec/w/cIgT1CJBv+beGMBFsiJgtcbdO4Zzmqm93B2DUvr4+tCVzRNyFTy2G7MYws s3HIyytbcaHf/PLTPgg0zBfwelltgxJUHwS6yn6geWtXUwFI9hBBKk+g48oMV2qU4u3wGXHitBCNN IzcYPO1J2FonHG3e6qgbPxDxCACX+MkRv3rudtK39mjOERNWY6Zx19MqsAFoslmB3A+o5/gXOCcF1 H9h7H6yFD9/nAEGAMKoo3aIFNfYbB451YbtjdjGQmVk8YmjmH/dO+7j6cnWjEXK4U64kZ7dW6GuAZ EWasNbakolfhRfkun4ZQ==; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669545316; 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; bh=a/FKhEJUKr4Au5jEDV0nA39boCfv1uOAmeL78/XZzlw=; b=ZiWJIwXTHsjSEHq8nmAktEDguAR5ZBAbFagwztjoL15CYq9GXM4SxOqpaYXHRKTbS1pN9e jPSH3sxop7DDk2Qsf6e7hqox/pF9rAGnzh/0LlLNO+yvnwwdwmmRAuewqVMMGL4mV+x151 w2ahB7HNB+KnDfIPqHjmPpm7Q2xo68A= In-Reply-To: <20221116102659.70287-17-david@redhat.com> Content-Language: en-US List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+glud-user-mode-linux-devel=m.gmane-mx.org@lists.infradead.org Content-Type: text/plain; charset="us-ascii"; format="flowed" To: linux-kernel@vger.kernel.org, Hans Verkuil , 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 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]. On top of mm-unstable, reverting this patch and applying [1] gives me an updated patch: From 1e66c25f1467c1f1e5f275312f2c6df29308d4df Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 16 Nov 2022 11:26:55 +0100 Subject: [PATCH] mm/frame-vector: remove FOLL_FORCE usage 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. Reviewed-by: Daniel Vetter Acked-by: Hans Verkuil 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 aad72640f055..8606fdacf5b8 100644 --- a/drivers/media/common/videobuf2/frame_vector.c +++ b/drivers/media/common/videobuf2/frame_vector.c @@ -41,7 +41,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write, int ret_pin_user_pages_fast = 0; int ret = 0; int err; - unsigned int gup_flags = FOLL_FORCE | FOLL_LONGTERM; + unsigned int gup_flags = FOLL_LONGTERM; if (nr_frames == 0) return 0; -- 2.38.1 Please let me know how you want to proceed. Ideally, you'd pick up [1] and apply this updated patch. Also, please tell me if I should send this updated patch in a separate mail (e.g., as reply to this mail). [1] https://lkml.kernel.org/r/71bdd3cf-b044-3f12-df58-7c16d5749587@xs4all.nl -- Thanks, David / dhildenb From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Date: Sun, 27 Nov 2022 10:35:09 +0000 Subject: Re: [PATCH mm-unstable v1 16/20] mm/frame-vector: remove FOLL_FORCE usage Message-Id: <81fb0fa3-2e06-b765-56ac-a7d981194e59@redhat.com> List-Id: References: <20221116102659.70287-1-david@redhat.com> <20221116102659.70287-17-david@redhat.com> In-Reply-To: <20221116102659.70287-17-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-kernel@vger.kernel.org, Hans Verkuil , 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 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]. On top of mm-unstable, reverting this patch and applying [1] gives me an updated patch: From 1e66c25f1467c1f1e5f275312f2c6df29308d4df Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 16 Nov 2022 11:26:55 +0100 Subject: [PATCH] mm/frame-vector: remove FOLL_FORCE usage 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. Reviewed-by: Daniel Vetter Acked-by: Hans Verkuil 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 aad72640f055..8606fdacf5b8 100644 --- a/drivers/media/common/videobuf2/frame_vector.c +++ b/drivers/media/common/videobuf2/frame_vector.c @@ -41,7 +41,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write, int ret_pin_user_pages_fast = 0; int ret = 0; int err; - unsigned int gup_flags = FOLL_FORCE | FOLL_LONGTERM; + unsigned int gup_flags = FOLL_LONGTERM; if (nr_frames = 0) return 0; -- 2.38.1 Please let me know how you want to proceed. Ideally, you'd pick up [1] and apply this updated patch. Also, please tell me if I should send this updated patch in a separate mail (e.g., as reply to this mail). [1] https://lkml.kernel.org/r/71bdd3cf-b044-3f12-df58-7c16d5749587@xs4all.nl -- Thanks, David / dhildenb 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 D0C00C4321E for ; Sun, 27 Nov 2022 10:37:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229526AbiK0KhE (ORCPT ); Sun, 27 Nov 2022 05:37:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52326 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229569AbiK0KhC (ORCPT ); Sun, 27 Nov 2022 05:37:02 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 35F65E09A for ; Sun, 27 Nov 2022 02:35:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669545314; 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; bh=a/FKhEJUKr4Au5jEDV0nA39boCfv1uOAmeL78/XZzlw=; b=O27xJtPpaXX+WGWtRHYJetfQf0LitOuWyYASTvh9BOIc76OBbAvqAJoksVcyj8ihyyybuL K0BzXUXxU998BrnvTHmhdCmjqJ56s5MlltXbtXEOh8pcP8m9+etTCwEOVSMLMxVzLD+KhE 02JICc1N+vm9jg/GhumwHtE2HYBwStg= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-594-J6SYX5xdOX-Zmtj-WHK1MA-1; Sun, 27 Nov 2022 05:35:13 -0500 X-MC-Unique: J6SYX5xdOX-Zmtj-WHK1MA-1 Received: by mail-wm1-f70.google.com with SMTP id 83-20020a1c0256000000b003d05a7cfe00so62594wmc.6 for ; Sun, 27 Nov 2022 02:35:13 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:subject:organization:from :content-language:references:cc:to:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=a/FKhEJUKr4Au5jEDV0nA39boCfv1uOAmeL78/XZzlw=; b=L559XInrge9IzTbVM14YP4mTPBtdWBUk5BK+cqMLBh3i/e489vgn1LniXlSsu7b1p5 1XKRrdOXHPPb7CmxeEWvQaH5qJEteYC37DJd8hEz3HRroAIVluA6WKWfXEGP1xgWDOVd cAcsZWwO9hvV7+wPYseyy93kZeYw6ftdXqUt54LdjzIaWZhQb+kU9h7Xg1zo1elQodCE 66Oo1+54lekSO6PG0na6yoRr7HgdvJJa4QE1MJknagLTxz2bsyu+OGcdt3KXq+iVp+LQ 7GwhiB5mhWhcetQvk6GUBC2d2iEbjr9bJwbFRlZ8ZYOivC2eBqL6N8GQLYA3ZpdTyjgv euQw== X-Gm-Message-State: ANoB5pkQ7L+7evGHy8BD9GttRgwhxhjsSQwCgtLQ4GJcYKJw1IwbhU+J epiGvlQ8AJHUw1sXs4a32oO8NjzmlsQRVSKZQfO+J3mZ3FJ7TGoX15LuJnkZP39yi0fwRI7bnMZ e922235/r9bhiw9azsu0Ps9MrWwmz X-Received: by 2002:a05:600c:4e88:b0:3b5:477:1e80 with SMTP id f8-20020a05600c4e8800b003b504771e80mr34594874wmq.200.1669545312139; Sun, 27 Nov 2022 02:35:12 -0800 (PST) X-Google-Smtp-Source: AA0mqf44zTk6J1KBaqs1seffTqR2+v9TqwwPSmjBWI2JrtJKUPaYELfhGu32bDJHUXiVwBKDfUuj3g== X-Received: by 2002:a05:600c:4e88:b0:3b5:477:1e80 with SMTP id f8-20020a05600c4e8800b003b504771e80mr34594816wmq.200.1669545311706; Sun, 27 Nov 2022 02:35:11 -0800 (PST) Received: from ?IPV6:2003:cb:c724:dc00:5ea8:da59:8609:7da? 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[2003:cb:c724:dc00:5ea8:da59:8609:7da]) by smtp.gmail.com with ESMTPSA id u10-20020a05600c19ca00b003c5571c27a1sm14797024wmq.32.2022.11.27.02.35.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 27 Nov 2022 02:35:11 -0800 (PST) Message-ID: <81fb0fa3-2e06-b765-56ac-a7d981194e59@redhat.com> Date: Sun, 27 Nov 2022 11:35:09 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 To: linux-kernel@vger.kernel.org, Hans Verkuil , 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> Content-Language: en-US From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH mm-unstable v1 16/20] mm/frame-vector: remove FOLL_FORCE usage In-Reply-To: <20221116102659.70287-17-david@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org 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]. On top of mm-unstable, reverting this patch and applying [1] gives me an updated patch: From 1e66c25f1467c1f1e5f275312f2c6df29308d4df Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 16 Nov 2022 11:26:55 +0100 Subject: [PATCH] mm/frame-vector: remove FOLL_FORCE usage 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. Reviewed-by: Daniel Vetter Acked-by: Hans Verkuil 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 aad72640f055..8606fdacf5b8 100644 --- a/drivers/media/common/videobuf2/frame_vector.c +++ b/drivers/media/common/videobuf2/frame_vector.c @@ -41,7 +41,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write, int ret_pin_user_pages_fast = 0; int ret = 0; int err; - unsigned int gup_flags = FOLL_FORCE | FOLL_LONGTERM; + unsigned int gup_flags = FOLL_LONGTERM; if (nr_frames == 0) return 0; -- 2.38.1 Please let me know how you want to proceed. Ideally, you'd pick up [1] and apply this updated patch. Also, please tell me if I should send this updated patch in a separate mail (e.g., as reply to this mail). [1] https://lkml.kernel.org/r/71bdd3cf-b044-3f12-df58-7c16d5749587@xs4all.nl -- Thanks, David / dhildenb 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5F094C4321E for ; Sun, 27 Nov 2022 10:35:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:Subject:From:References:Cc:To: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=G1LxGg6lThxykOMDsBO+gkd4mNaE+E0lcZrZBvY3ckQ=; b=aDz5WzCYsLrzzS tC2pC/WUtCjXxhec/w/cIgT1CJBv+beGMBFsiJgtcbdO4Zzmqm93B2DUvr4+tCVzRNyFTy2G7MYws s3HIyytbcaHf/PLTPgg0zBfwelltgxJUHwS6yn6geWtXUwFI9hBBKk+g48oMV2qU4u3wGXHitBCNN IzcYPO1J2FonHG3e6qgbPxDxCACX+MkRv3rudtK39mjOERNWY6Zx19MqsAFoslmB3A+o5/gXOCcF1 H9h7H6yFD9/nAEGAMKoo3aIFNfYbB451YbtjdjGQmVk8YmjmH/dO+7j6cnWjEXK4U64kZ7dW6GuAZ EWasNbakolfhRfkun4ZQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ozF0J-00Aqta-Mj; Sun, 27 Nov 2022 10:35:19 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ozF0H-00AqsC-6g for linux-um@lists.infradead.org; Sun, 27 Nov 2022 10:35:18 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669545316; 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; bh=a/FKhEJUKr4Au5jEDV0nA39boCfv1uOAmeL78/XZzlw=; b=ZiWJIwXTHsjSEHq8nmAktEDguAR5ZBAbFagwztjoL15CYq9GXM4SxOqpaYXHRKTbS1pN9e jPSH3sxop7DDk2Qsf6e7hqox/pF9rAGnzh/0LlLNO+yvnwwdwmmRAuewqVMMGL4mV+x151 w2ahB7HNB+KnDfIPqHjmPpm7Q2xo68A= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-592-5kI_V4KZOk6ud1j95iO5FA-1; Sun, 27 Nov 2022 05:35:13 -0500 X-MC-Unique: 5kI_V4KZOk6ud1j95iO5FA-1 Received: by mail-wm1-f69.google.com with SMTP id ay40-20020a05600c1e2800b003cf8aa16377so4822969wmb.7 for ; Sun, 27 Nov 2022 02:35:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:subject:organization:from :content-language:references:cc:to:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=a/FKhEJUKr4Au5jEDV0nA39boCfv1uOAmeL78/XZzlw=; b=YVny/5Ld/oy7ayCiNJ2E8PcP+NbDHNBgmTkMnuegPnrvhFWhoSkT54Kz637JdGEDgj m7wU16U0J7nFq5pkMRAU68FT5aMq+xgDzvGk33rdD3HHitg1whytTlvxQHgwHabIA/Yj eDSqV8WUjWncYXQKEu2xR7f5GU4JSfynBYOcMyHZdx2pyjVPdj0+EIeeG4FjNLi/6zYC bcw+Oa0zJEh69Izil/zZqho3V784TwEFBsDp630gJudFHSaZBAS81V608Zuve12GRemT GnS6rZUOnmnRwMplA2DXKGTGx5O62FLTZWoqLREUSKtDmacpaIZpfsW1NaomREDilPUT +3dQ== X-Gm-Message-State: ANoB5pnCXmoVCocH8/+npXK2PlZ68ZQGvfugcUGXAqdu83ySXel1Fqrc 9mYBOdSgg6hbhKtlmcsKQZnJvJgsbUXIS+i+uMwnzTglOKkdwl6fIGMscOfULPDZbOjMsF0D88q DjKnnwrYWlOlB6SX07wDgYUDK X-Received: by 2002:a05:600c:4e88:b0:3b5:477:1e80 with SMTP id f8-20020a05600c4e8800b003b504771e80mr34594848wmq.200.1669545311983; Sun, 27 Nov 2022 02:35:11 -0800 (PST) X-Google-Smtp-Source: AA0mqf44zTk6J1KBaqs1seffTqR2+v9TqwwPSmjBWI2JrtJKUPaYELfhGu32bDJHUXiVwBKDfUuj3g== X-Received: by 2002:a05:600c:4e88:b0:3b5:477:1e80 with SMTP id f8-20020a05600c4e8800b003b504771e80mr34594816wmq.200.1669545311706; Sun, 27 Nov 2022 02:35:11 -0800 (PST) Received: from ?IPV6:2003:cb:c724:dc00:5ea8:da59:8609:7da? 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[2003:cb:c724:dc00:5ea8:da59:8609:7da]) by smtp.gmail.com with ESMTPSA id u10-20020a05600c19ca00b003c5571c27a1sm14797024wmq.32.2022.11.27.02.35.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 27 Nov 2022 02:35:11 -0800 (PST) Message-ID: <81fb0fa3-2e06-b765-56ac-a7d981194e59@redhat.com> Date: Sun, 27 Nov 2022 11:35:09 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 To: linux-kernel@vger.kernel.org, Hans Verkuil , 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> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH mm-unstable v1 16/20] mm/frame-vector: remove FOLL_FORCE usage In-Reply-To: <20221116102659.70287-17-david@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221127_023517_328772_B86B5478 X-CRM114-Status: GOOD ( 27.96 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org 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]. On top of mm-unstable, reverting this patch and applying [1] gives me an updated patch: From 1e66c25f1467c1f1e5f275312f2c6df29308d4df Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 16 Nov 2022 11:26:55 +0100 Subject: [PATCH] mm/frame-vector: remove FOLL_FORCE usage 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. Reviewed-by: Daniel Vetter Acked-by: Hans Verkuil 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 aad72640f055..8606fdacf5b8 100644 --- a/drivers/media/common/videobuf2/frame_vector.c +++ b/drivers/media/common/videobuf2/frame_vector.c @@ -41,7 +41,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write, int ret_pin_user_pages_fast = 0; int ret = 0; int err; - unsigned int gup_flags = FOLL_FORCE | FOLL_LONGTERM; + unsigned int gup_flags = FOLL_LONGTERM; if (nr_frames == 0) return 0; -- 2.38.1 Please let me know how you want to proceed. Ideally, you'd pick up [1] and apply this updated patch. Also, please tell me if I should send this updated patch in a separate mail (e.g., as reply to this mail). [1] https://lkml.kernel.org/r/71bdd3cf-b044-3f12-df58-7c16d5749587@xs4all.nl -- Thanks, David / dhildenb _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 198BFC4321E for ; Sun, 27 Nov 2022 10:36:24 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4NKlPy1nPvz3cGc for ; Sun, 27 Nov 2022 21:36:22 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=O27xJtPp; 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[2003:cb:c724:dc00:5ea8:da59:8609:7da]) by smtp.gmail.com with ESMTPSA id u10-20020a05600c19ca00b003c5571c27a1sm14797024wmq.32.2022.11.27.02.35.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 27 Nov 2022 02:35:11 -0800 (PST) Message-ID: <81fb0fa3-2e06-b765-56ac-a7d981194e59@redhat.com> Date: Sun, 27 Nov 2022 11:35:09 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 To: linux-kernel@vger.kernel.org, Hans Verkuil , Andrew Morton References: <20221116102659.70287-1-david@redhat.com> <20221116102659.70287-17-david@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH mm-unstable v1 16/20] mm/frame-vector: remove FOLL_FORCE usage In-Reply-To: <20221116102659.70287-17-david@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, Greg Kroah-Hartman , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, Nadav Amit , linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, Shuah Khan , Marek Szyprowski , Andrea Arcangeli , linux-samsung-soc@vger.kernel.org, linux-rdma@vger.kernel.org, David Airlie , x86@kernel.org, Hugh Dickins , Matthew Wilcox , Christoph Hellwig , Jason Gunthorpe , Vlastimil Babka , linux-media@vger.kernel.org, Arnd Bergmann , John Hubbard , linux-um@lists.infradead.org, etnaviv@lists.freedesktop.org, Alex Williamson , Peter Xu , Muchun Song , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linuxppc-dev @lists.ozlabs.org, Oded Gabbay , linux-mips@vger.kernel.org, Tomasz Figa , linux-perf-users@vger.kernel.org, linux-security-module@vger.kernel.org, linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Lucas Stach , Linus Torvalds , Mike Kravetz Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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]. On top of mm-unstable, reverting this patch and applying [1] gives me an updated patch: From 1e66c25f1467c1f1e5f275312f2c6df29308d4df Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 16 Nov 2022 11:26:55 +0100 Subject: [PATCH] mm/frame-vector: remove FOLL_FORCE usage 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. Reviewed-by: Daniel Vetter Acked-by: Hans Verkuil 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 aad72640f055..8606fdacf5b8 100644 --- a/drivers/media/common/videobuf2/frame_vector.c +++ b/drivers/media/common/videobuf2/frame_vector.c @@ -41,7 +41,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write, int ret_pin_user_pages_fast = 0; int ret = 0; int err; - unsigned int gup_flags = FOLL_FORCE | FOLL_LONGTERM; + unsigned int gup_flags = FOLL_LONGTERM; if (nr_frames == 0) return 0; -- 2.38.1 Please let me know how you want to proceed. Ideally, you'd pick up [1] and apply this updated patch. Also, please tell me if I should send this updated patch in a separate mail (e.g., as reply to this mail). [1] https://lkml.kernel.org/r/71bdd3cf-b044-3f12-df58-7c16d5749587@xs4all.nl -- Thanks, David / dhildenb 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4AC59C4321E for ; Sun, 27 Nov 2022 10:36:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:Subject:From:References:Cc:To: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=dBW837pyybpMdkripja414GD95GOduTqxhZKtUFuDfM=; b=yHaQcv398FGyAR avd5xM/yAJ6xKiVOsOygttHVgKExqMNL+JbaO35+5O/uhlS4LDAXVjF87HkQWdrIE/7qNOui8n5lS nMwq6UvUMSA9ij2iTJgPUscc72lzD9qE+gS3QHYgmtOeOakJo+gNilMMkKyjvpe1HxtZFNiIYt5Jp yd3OoiMxTexwiToh7gAmTJ+zoPSXURtDRo45qc5H+P6pyobvaAbW4+8KEN+KHZpKCOl02unPNOl0d yJS5dV7oc5AiQztxWDP9lqm4Kv7L9gBvj0zYe6L4vUtA2LL1R8dWZ4g8+iyiMuCUiQ3pxnE5VaBzl rIpRwLn0y9KETuZWzzTg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ozF0N-00AquD-7L; Sun, 27 Nov 2022 10:35:23 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ozF0H-00AqrB-Nl for linux-arm-kernel@lists.infradead.org; Sun, 27 Nov 2022 10:35:20 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669545314; 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; bh=a/FKhEJUKr4Au5jEDV0nA39boCfv1uOAmeL78/XZzlw=; b=O27xJtPpaXX+WGWtRHYJetfQf0LitOuWyYASTvh9BOIc76OBbAvqAJoksVcyj8ihyyybuL K0BzXUXxU998BrnvTHmhdCmjqJ56s5MlltXbtXEOh8pcP8m9+etTCwEOVSMLMxVzLD+KhE 02JICc1N+vm9jg/GhumwHtE2HYBwStg= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-217-JfG2tzjUNryrU04OzBNc9w-1; Sun, 27 Nov 2022 05:35:13 -0500 X-MC-Unique: JfG2tzjUNryrU04OzBNc9w-1 Received: by mail-wm1-f72.google.com with SMTP id l42-20020a05600c1d2a00b003cf8e70c1ecso6993505wms.4 for ; Sun, 27 Nov 2022 02:35:13 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:subject:organization:from :content-language:references:cc:to:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=a/FKhEJUKr4Au5jEDV0nA39boCfv1uOAmeL78/XZzlw=; b=M8D/VYrpInYPkfxkF2WLY6yD39Oyg7/GiNFXf6MJG37ZKSdltH9v+HNlCYV58mfd4W aOD9OHrMAAEs3Yabg5c43KvAA+HuYUwoVkRyej4swY8Y5MKkEPnSUl7vp3L8xdlwsnrl 4nr/Gk2C0po382Ks4alDpbUhUzLE+9cMgpiCyVSzTH4WUpWuJMQFn1NKn2xbtmWHyDQ2 tPQGRoWqlTkxfCBkHSb2zTOjNmzXa8uxkefViudJlMbxHDgVOZP9cbRBQyggD7aXUkfo Ku193uPP7EwBpJUm0I0PElK2KBa/D0XzQ0d6OTe/xN/ql7BJUPi4HDEycv9iOvpvkhMk W4tA== X-Gm-Message-State: ANoB5pm/XqxfZ560NabPwuRD/iYfdI5yqmOZpIbHgDsqkl40Pl3oHVZD MBlV91gRB2XMjQ62QRkvxIXyYUtV7yijKhyhnK7jg7Gjo+JCF4ggXqX0sYZblnyXSvrykNG15rC PyFROZQlNaziMHpAueFdsfyD4kbhIUGzFGLs= X-Received: by 2002:a05:600c:4e88:b0:3b5:477:1e80 with SMTP id f8-20020a05600c4e8800b003b504771e80mr34594826wmq.200.1669545311973; Sun, 27 Nov 2022 02:35:11 -0800 (PST) X-Google-Smtp-Source: AA0mqf44zTk6J1KBaqs1seffTqR2+v9TqwwPSmjBWI2JrtJKUPaYELfhGu32bDJHUXiVwBKDfUuj3g== X-Received: by 2002:a05:600c:4e88:b0:3b5:477:1e80 with SMTP id f8-20020a05600c4e8800b003b504771e80mr34594816wmq.200.1669545311706; Sun, 27 Nov 2022 02:35:11 -0800 (PST) Received: from ?IPV6:2003:cb:c724:dc00:5ea8:da59:8609:7da? 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[2003:cb:c724:dc00:5ea8:da59:8609:7da]) by smtp.gmail.com with ESMTPSA id u10-20020a05600c19ca00b003c5571c27a1sm14797024wmq.32.2022.11.27.02.35.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 27 Nov 2022 02:35:11 -0800 (PST) Message-ID: <81fb0fa3-2e06-b765-56ac-a7d981194e59@redhat.com> Date: Sun, 27 Nov 2022 11:35:09 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 To: linux-kernel@vger.kernel.org, Hans Verkuil , 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> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH mm-unstable v1 16/20] mm/frame-vector: remove FOLL_FORCE usage In-Reply-To: <20221116102659.70287-17-david@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221127_023517_878857_A3CB9B85 X-CRM114-Status: GOOD ( 29.48 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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]. On top of mm-unstable, reverting this patch and applying [1] gives me an updated patch: From 1e66c25f1467c1f1e5f275312f2c6df29308d4df Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 16 Nov 2022 11:26:55 +0100 Subject: [PATCH] mm/frame-vector: remove FOLL_FORCE usage 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. Reviewed-by: Daniel Vetter Acked-by: Hans Verkuil 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 aad72640f055..8606fdacf5b8 100644 --- a/drivers/media/common/videobuf2/frame_vector.c +++ b/drivers/media/common/videobuf2/frame_vector.c @@ -41,7 +41,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write, int ret_pin_user_pages_fast = 0; int ret = 0; int err; - unsigned int gup_flags = FOLL_FORCE | FOLL_LONGTERM; + unsigned int gup_flags = FOLL_LONGTERM; if (nr_frames == 0) return 0; -- 2.38.1 Please let me know how you want to proceed. Ideally, you'd pick up [1] and apply this updated patch. Also, please tell me if I should send this updated patch in a separate mail (e.g., as reply to this mail). [1] https://lkml.kernel.org/r/71bdd3cf-b044-3f12-df58-7c16d5749587@xs4all.nl -- Thanks, David / dhildenb _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D25ABC4321E for ; Sun, 27 Nov 2022 10:35:19 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6F50A10E074; Sun, 27 Nov 2022 10:35:18 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id A6EE110E18D for ; Sun, 27 Nov 2022 10:35:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669545314; 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; bh=a/FKhEJUKr4Au5jEDV0nA39boCfv1uOAmeL78/XZzlw=; b=O27xJtPpaXX+WGWtRHYJetfQf0LitOuWyYASTvh9BOIc76OBbAvqAJoksVcyj8ihyyybuL K0BzXUXxU998BrnvTHmhdCmjqJ56s5MlltXbtXEOh8pcP8m9+etTCwEOVSMLMxVzLD+KhE 02JICc1N+vm9jg/GhumwHtE2HYBwStg= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-529-Qzq1tQ4BMpKhRqmmEeGswg-1; Sun, 27 Nov 2022 05:35:13 -0500 X-MC-Unique: Qzq1tQ4BMpKhRqmmEeGswg-1 Received: by mail-wr1-f72.google.com with SMTP id o8-20020adfba08000000b00241e80f08e0so1299878wrg.12 for ; Sun, 27 Nov 2022 02:35:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:subject:organization:from :content-language:references:cc:to:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=a/FKhEJUKr4Au5jEDV0nA39boCfv1uOAmeL78/XZzlw=; b=uDCI8jTlA/G5YXFJeJrTMhwMgSQa6S+fki5x92V7fekb7Kw5169aOOTKZpx4Gi2Tpr uN8fI2cfyUsyrbNsmXyPIj77VKi8ip2zkrO+JHjWgP+RXX6segmMLvyI9WTUq1KoWgiO QSQRTJ6F5uXwi10qWkpzYNFroueuRFVYMS1tLntf/Ffu6StMkbv43JPgajgB/YLO1ysI H7DN0TeWh8C79y6VuFCKs3AhtCnqLnsBjKQIgFPLBhhITDPtkfaPGjDj15RsFu6V30Ff 9QIuOplGvpk28UyCxelTmdpV6o4KThjQR+JOHsRAqTjEswu/C3rW03uKJR3BxxfZF94U YSFQ== X-Gm-Message-State: ANoB5pnzyANUXSCQYTitvDGZQMntaVLvW8vXNfwDlmggPA9fSV5QYcbq jV7KEYk34bhk2ac4fXyIkT4PhzAu4dL95lPNP6RzGsrKsdrL6AMoZQQs2dOrw/Bw6t+/aw/je1W wh8n9W7Tny9RMJvxSUU6YbW2rq9/Z X-Received: by 2002:a05:600c:4e88:b0:3b5:477:1e80 with SMTP id f8-20020a05600c4e8800b003b504771e80mr34594830wmq.200.1669545311975; Sun, 27 Nov 2022 02:35:11 -0800 (PST) X-Google-Smtp-Source: AA0mqf44zTk6J1KBaqs1seffTqR2+v9TqwwPSmjBWI2JrtJKUPaYELfhGu32bDJHUXiVwBKDfUuj3g== X-Received: by 2002:a05:600c:4e88:b0:3b5:477:1e80 with SMTP id f8-20020a05600c4e8800b003b504771e80mr34594816wmq.200.1669545311706; Sun, 27 Nov 2022 02:35:11 -0800 (PST) Received: from ?IPV6:2003:cb:c724:dc00:5ea8:da59:8609:7da? 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[2003:cb:c724:dc00:5ea8:da59:8609:7da]) by smtp.gmail.com with ESMTPSA id u10-20020a05600c19ca00b003c5571c27a1sm14797024wmq.32.2022.11.27.02.35.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 27 Nov 2022 02:35:11 -0800 (PST) Message-ID: <81fb0fa3-2e06-b765-56ac-a7d981194e59@redhat.com> Date: Sun, 27 Nov 2022 11:35:09 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.1 To: linux-kernel@vger.kernel.org, Hans Verkuil , Andrew Morton References: <20221116102659.70287-1-david@redhat.com> <20221116102659.70287-17-david@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH mm-unstable v1 16/20] mm/frame-vector: remove FOLL_FORCE usage In-Reply-To: <20221116102659.70287-17-david@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, Greg Kroah-Hartman , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, Nadav Amit , linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, Shuah Khan , Marek Szyprowski , Andrea Arcangeli , linux-samsung-soc@vger.kernel.org, linux-rdma@vger.kernel.org, x86@kernel.org, Hugh Dickins , Matthew Wilcox , Christoph Hellwig , Jason Gunthorpe , Vlastimil Babka , linux-media@vger.kernel.org, Arnd Bergmann , John Hubbard , linux-um@lists.infradead.org, etnaviv@lists.freedesktop.org, Alex Williamson , Peter Xu , Muchun Song , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, Oded Gabbay , linux-mips@vger.kernel.org, Tomasz Figa , linux-perf-users@vger.kernel.org, linux-security-module@vger.kernel.org, linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, Linus Torvalds , Mike Kravetz Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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]. On top of mm-unstable, reverting this patch and applying [1] gives me an updated patch: From 1e66c25f1467c1f1e5f275312f2c6df29308d4df Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 16 Nov 2022 11:26:55 +0100 Subject: [PATCH] mm/frame-vector: remove FOLL_FORCE usage 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. Reviewed-by: Daniel Vetter Acked-by: Hans Verkuil 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 aad72640f055..8606fdacf5b8 100644 --- a/drivers/media/common/videobuf2/frame_vector.c +++ b/drivers/media/common/videobuf2/frame_vector.c @@ -41,7 +41,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write, int ret_pin_user_pages_fast = 0; int ret = 0; int err; - unsigned int gup_flags = FOLL_FORCE | FOLL_LONGTERM; + unsigned int gup_flags = FOLL_LONGTERM; if (nr_frames == 0) return 0; -- 2.38.1 Please let me know how you want to proceed. Ideally, you'd pick up [1] and apply this updated patch. Also, please tell me if I should send this updated patch in a separate mail (e.g., as reply to this mail). [1] https://lkml.kernel.org/r/71bdd3cf-b044-3f12-df58-7c16d5749587@xs4all.nl -- Thanks, David / dhildenb