The patch titled
Subject: media: videobuf-dma-sg: remove FOLL_FORCE usage
has been added to the -mm mm-unstable branch. Its filename is
media-videobuf-dma-sg-remove-foll_force-usage.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/media-videobuf-dma-sg-remove-foll_force-usage.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: media: videobuf-dma-sg: remove FOLL_FORCE usage
Date: Wed, 16 Nov 2022 11:26:52 +0100
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.
Link: https://lkml.kernel.org/r/20221116102659.70287-14-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/media/v4l2-core/videobuf-dma-sg.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)
--- a/drivers/media/v4l2-core/videobuf-dma-sg.c~media-videobuf-dma-sg-remove-foll_force-usage
+++ a/drivers/media/v4l2-core/videobuf-dma-sg.c
@@ -151,17 +151,16 @@ static void videobuf_dma_init(struct vid
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
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;
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
selftests-vm-add-ksm-unmerge-tests.patch
mm-pagewalk-dont-trigger-test_walk-in-walk_page_vma.patch
selftests-vm-add-test-to-measure-madv_unmergeable-performance.patch
mm-ksm-simplify-break_ksm-to-not-rely-on-vm_fault_write.patch
mm-remove-vm_fault_write.patch
mm-ksm-fix-ksm-cow-breaking-with-userfaultfd-wp-via-fault_flag_unshare.patch
mm-pagewalk-add-walk_page_range_vma.patch
mm-ksm-convert-break_ksm-to-use-walk_page_range_vma.patch
mm-gup-remove-foll_migration.patch
mm-mprotect-minor-can_change_pte_writable-cleanups.patch
mm-huge_memory-try-avoiding-write-faults-when-changing-pmd-protection.patch
mm-mprotect-factor-out-check-whether-manual-pte-write-upgrades-are-required.patch
mm-autonuma-use-can_change_ptepmd_writable-to-replace-savedwrite.patch
mm-remove-unused-savedwrite-infrastructure.patch
selftests-vm-anon_cow-add-mprotect-optimization-tests.patch
selftests-vm-anon_cow-prepare-for-non-anonymous-cow-tests.patch
selftests-vm-cow-basic-cow-tests-for-non-anonymous-pages.patch
selftests-vm-cow-r-o-long-term-pinning-reliability-tests-for-non-anon-pages.patch
mm-add-early-fault_flag_unshare-consistency-checks.patch
mm-add-early-fault_flag_write-consistency-checks.patch
mm-rework-handling-in-do_wp_page-based-on-private-vs-shared-mappings.patch
mm-dont-call-vm_ops-huge_fault-in-wp_huge_pmd-wp_huge_pud-for-private-mappings.patch
mm-extend-fault_flag_unshare-support-to-anything-in-a-cow-mapping.patch
mm-gup-reliable-r-o-long-term-pinning-in-cow-mappings.patch
rdma-umem-remove-foll_force-usage.patch
rdma-usnic-remove-foll_force-usage.patch
rdma-siw-remove-foll_force-usage.patch
media-videobuf-dma-sg-remove-foll_force-usage.patch
drm-etnaviv-remove-foll_force-usage.patch
media-pci-ivtv-remove-foll_force-usage.patch
mm-frame-vector-remove-foll_force-usage.patch
drm-exynos-remove-foll_force-usage.patch
rdma-hw-qib-qib_user_pages-remove-foll_force-usage.patch
habanalabs-remove-foll_force-usage.patch
