+ drm-etnaviv-remove-foll_force-usage.patch added to mm-unstable branch

+ drm-etnaviv-remove-foll_force-usage.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: drm/etnaviv: remove FOLL_FORCE usage
has been added to the -mm mm-unstable branch.  Its filename is
     drm-etnaviv-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/drm-etnaviv-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@redhat.com>
Subject: drm/etnaviv: remove FOLL_FORCE usage
Date: Wed, 16 Nov 2022 11:26:53 +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()).

commit cd5297b0855f ("drm/etnaviv: Use FOLL_FORCE for userptr")
documents that FOLL_FORCE | FOLL_WRITE was really only used for reliable
R/O pinning.

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/20221116102659.70287-15-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Russell King <linux+etnaviv@armlinux.org.uk>
Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: David Airlie <airlied@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/gpu/drm/etnaviv/etnaviv_gem.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c~drm-etnaviv-remove-foll_force-usage
+++ a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -638,6 +638,7 @@ static int etnaviv_gem_userptr_get_pages
 	struct page **pvec = NULL;
 	struct etnaviv_gem_userptr *userptr = &etnaviv_obj->userptr;
 	int ret, pinned = 0, npages = etnaviv_obj->base.size >> PAGE_SHIFT;
+	unsigned int gup_flags = FOLL_LONGTERM;
 
 	might_lock_read(&current->mm->mmap_lock);
 
@@ -648,14 +649,15 @@ static int etnaviv_gem_userptr_get_pages
 	if (!pvec)
 		return -ENOMEM;
 
+	if (!userptr->ro)
+		gup_flags |= FOLL_WRITE;
+
 	do {
 		unsigned num_pages = npages - pinned;
 		uint64_t ptr = userptr->ptr + pinned * PAGE_SIZE;
 		struct page **pages = pvec + pinned;
 
-		ret = pin_user_pages_fast(ptr, num_pages,
-					  FOLL_WRITE | FOLL_FORCE | FOLL_LONGTERM,
-					  pages);
+		ret = pin_user_pages_fast(ptr, num_pages, gup_flags, pages);
 		if (ret < 0) {
 			unpin_user_pages(pvec, pinned);
 			kvfree(pvec);
_

Patches currently in -mm which might be from david@redhat.com 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