From: Hans Verkuil <hverkuil@xs4all.nl>
To: David Hildenbrand <david@redhat.com>, 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,
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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 <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jason Gunthorpe <jgg@ziepe.ca>,
John Hubbard <jhubbard@nvidia.com>, Peter Xu <peterx@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Hugh Dickins <hughd@google.com>, Nadav Amit <namit@vmware.com>,
Vlastimil Babka <vbabka@suse.cz>,
Matthew Wilcox <willy@infradead.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Muchun Song <songmuchun@bytedance.com>,
Shuah Khan <shuah@kernel.org>,
Lucas Stach <l.stach@pengutronix.de>,
David Airlie <airlied@gmail.com>,
Oded Gabbay <ogabbay@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Christoph Hellwig <hch@infradead.org>,
Alex Williamson <alex.williamson@redhat.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>
Subject: Re: [PATCH mm-unstable v1 13/20] media: videobuf-dma-sg: remove FOLL_FORCE usage
Date: Wed, 23 Nov 2022 14:17:35 +0100 [thread overview]
Message-ID: <73481668-9c41-7d01-d328-bd137a57c0b3@xs4all.nl> (raw)
In-Reply-To: <20221116102659.70287-14-david@redhat.com>
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 <mchehab@kernel.org>
> Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
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;
next prev parent reply other threads:[~2022-11-23 13:33 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-16 10:26 [PATCH mm-unstable v1 00/20] mm/gup: remove FOLL_FORCE usage from drivers (reliable R/O long-term pinning) David Hildenbrand
2022-11-16 10:26 ` [PATCH mm-unstable v1 01/20] selftests/vm: anon_cow: prepare for non-anonymous COW tests David Hildenbrand
2022-11-18 16:20 ` Vlastimil Babka
2022-11-16 10:26 ` [PATCH mm-unstable v1 02/20] selftests/vm: cow: basic COW tests for non-anonymous pages David Hildenbrand
2022-11-16 10:26 ` [PATCH mm-unstable v1 03/20] selftests/vm: cow: R/O long-term pinning reliability tests for non-anon pages David Hildenbrand
2022-11-16 10:26 ` [PATCH mm-unstable v1 04/20] mm: add early FAULT_FLAG_UNSHARE consistency checks David Hildenbrand
2022-11-18 16:45 ` Vlastimil Babka
2022-11-16 10:26 ` [PATCH mm-unstable v1 05/20] mm: add early FAULT_FLAG_WRITE " David Hildenbrand
2022-11-18 17:03 ` Vlastimil Babka
2022-11-16 10:26 ` [PATCH mm-unstable v1 06/20] mm: rework handling in do_wp_page() based on private vs. shared mappings David Hildenbrand
2022-11-22 14:20 ` Vlastimil Babka
2022-11-16 10:26 ` [PATCH mm-unstable v1 07/20] mm: don't call vm_ops->huge_fault() in wp_huge_pmd()/wp_huge_pud() for private mappings David Hildenbrand
2022-11-22 14:50 ` Vlastimil Babka
2022-11-16 10:26 ` [PATCH mm-unstable v1 08/20] mm: extend FAULT_FLAG_UNSHARE support to anything in a COW mapping David Hildenbrand
2022-11-22 15:35 ` Vlastimil Babka
2022-11-16 10:26 ` [PATCH mm-unstable v1 09/20] mm/gup: reliable R/O long-term pinning in COW mappings David Hildenbrand
2022-11-16 10:42 ` Daniel Vetter
2022-11-22 16:29 ` Vlastimil Babka
2022-11-24 1:29 ` John Hubbard
2022-11-16 10:26 ` [PATCH mm-unstable v1 10/20] RDMA/umem: remove FOLL_FORCE usage David Hildenbrand
2022-11-17 0:45 ` Jason Gunthorpe
2022-11-16 10:26 ` [PATCH mm-unstable v1 11/20] RDMA/usnic: " David Hildenbrand
2022-11-17 0:45 ` Jason Gunthorpe
2022-11-16 10:26 ` [PATCH mm-unstable v1 12/20] RDMA/siw: " David Hildenbrand
2022-11-17 0:46 ` Jason Gunthorpe
2022-11-16 10:26 ` [PATCH mm-unstable v1 13/20] media: videobuf-dma-sg: " David Hildenbrand
2022-11-16 10:48 ` Daniel Vetter
2022-11-23 13:17 ` Hans Verkuil [this message]
2022-11-16 10:26 ` [PATCH mm-unstable v1 14/20] drm/etnaviv: " David Hildenbrand
2022-11-16 10:49 ` Daniel Vetter
2022-11-16 10:26 ` [PATCH mm-unstable v1 15/20] media: pci/ivtv: " David Hildenbrand
2022-11-23 13:18 ` Hans Verkuil
2022-11-16 10:26 ` [PATCH mm-unstable v1 16/20] mm/frame-vector: " David Hildenbrand
2022-11-16 10:50 ` Daniel Vetter
2022-11-23 13:26 ` Hans Verkuil
2022-11-23 14:28 ` Hans Verkuil
2022-11-27 10:35 ` David Hildenbrand
2022-11-28 8:17 ` Hans Verkuil
2022-11-28 8:18 ` David Hildenbrand
2022-11-28 8:26 ` Hans Verkuil
2022-11-28 8:57 ` Tomasz Figa
2022-11-28 22:59 ` Andrew Morton
2022-11-29 8:48 ` David Hildenbrand
2022-11-29 9:08 ` Hans Verkuil
2022-11-29 9:15 ` David Hildenbrand
2022-11-16 10:26 ` [PATCH mm-unstable v1 17/20] drm/exynos: " David Hildenbrand
2022-11-16 10:50 ` Daniel Vetter
2022-11-16 10:26 ` [PATCH mm-unstable v1 18/20] RDMA/hw/qib/qib_user_pages: " David Hildenbrand
2022-11-16 10:26 ` [PATCH mm-unstable v1 19/20] habanalabs: " David Hildenbrand
2022-11-16 10:26 ` [PATCH mm-unstable v1 20/20] mm: rename FOLL_FORCE to FOLL_PTRACE David Hildenbrand
2022-11-16 18:16 ` Linus Torvalds
2022-11-16 18:53 ` David Hildenbrand
2022-11-17 22:58 ` Kees Cook
2022-11-17 23:20 ` Linus Torvalds
2022-11-18 0:31 ` Kees Cook
2022-11-18 11:09 ` Peter Zijlstra
2022-11-18 22:29 ` Kees Cook
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