+ mm-vma-update-vmg_adjust_set_range-to-offset-pgoff-instead.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/vma: update vmg_adjust_set_range() to offset pgoff instead
has been added to the -mm mm-new branch.  Its filename is
     mm-vma-update-vmg_adjust_set_range-to-offset-pgoff-instead.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vma-update-vmg_adjust_set_range-to-offset-pgoff-instead.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Lorenzo Stoakes <ljs@kernel.org>
Subject: mm/vma: update vmg_adjust_set_range() to offset pgoff instead
Date: Fri, 10 Jul 2026 21:17:08 +0100

We are calculating the pgoff as an offset, since we have vma_add_pgoff()
and vma_sub_pgoff() available, just offset this value directly and use
__vma_set_range() for vma->vm_[start, end] values.

We take care to update the range before offsetting the page offset, so the
adjusted VMA's vm_start and vm_pgoff are mutually consistent at the point
the page offset helpers operate - this matters once vma_set_pgoff() comes
to assert invariants which relate the two.

Doing so lays the foundation for future work which allows for use of
virtual page offsets for MAP_PRIVATE-file backed mappings.

No functional change intended.

Link: https://lore.kernel.org/20260710-b4-pre-scalable-cow-v2-27-2a5aa403d977@kernel.org
Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Gregory Price <gourry@gourry.net>
Cc: Ackerley Tng <ackerleytng@google.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Kai Huang <kai.huang@intel.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: SJ Park <sj@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vma.c |   15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

--- a/mm/vma.c~mm-vma-update-vmg_adjust_set_range-to-offset-pgoff-instead
+++ a/mm/vma.c
@@ -714,9 +714,6 @@ void validate_mm(struct mm_struct *mm)
  */
 static void vmg_adjust_set_range(struct vma_merge_struct *vmg)
 {
-	struct vm_area_struct *adjust;
-	pgoff_t pgoff;
-
 	if (vmg->__adjust_middle_start) {
 		/*
 		 * vmg->start    vmg->end
@@ -735,8 +732,8 @@ static void vmg_adjust_set_range(struct
 		struct vm_area_struct *middle = vmg->middle;
 		const unsigned long delta = vmg->end - middle->vm_start;
 
-		pgoff = vma_start_pgoff(middle) + (delta >> PAGE_SHIFT);
-		adjust = middle;
+		__vma_set_range(middle, vmg->end, middle->vm_end);
+		vma_add_pgoff(middle, delta >> PAGE_SHIFT);
 	} else if (vmg->__adjust_next_start) {
 		/*
 		 *                Originally:
@@ -764,13 +761,9 @@ static void vmg_adjust_set_range(struct
 		struct vm_area_struct *next = vmg->next;
 		const unsigned long delta = next->vm_start - vmg->end;
 
-		pgoff = vma_start_pgoff(next) - (delta >> PAGE_SHIFT);
-		adjust = next;
-	} else {
-		return;
+		__vma_set_range(next, vmg->end, next->vm_end);
+		vma_sub_pgoff(next, delta >> PAGE_SHIFT);
 	}
-
-	vma_set_range(adjust, vmg->end, adjust->vm_end, pgoff);
 }
 
 /*
_

Patches currently in -mm which might be from ljs@kernel.org are

mm-move-alloc-tag-to-mm.patch
mm-ptdump-always-stabilise-against-page-table-freeing-using-init_mm.patch
mm-vmalloc-acquire-init_mm-read-lock-on-huge-vmap-promotion.patch
revert-arm64-enable-vmalloc-huge-with-ptdump.patch
mm-move-vma_start_pgoff-into-mmh-and-clean-up.patch
mm-add-kdoc-comments-for-vma_start-last_pgoff.patch
tools-testing-vma-use-vma_start_pgoff-in-merge-tests.patch
mm-introduce-and-use-vma_end_pgoff.patch
mm-rmap-update-mm-interval_treec-comments.patch
mm-rmap-parameterise-vma_interval_tree_-by-address_space.patch
mm-rmap-elide-unnecessary-static-inlines-in-interval_treec.patch
mm-rmap-rename-vma_interval_tree_-to-mapping_rmap_tree_.patch
mm-rmap-parameterise-anon_vma_interval_tree_-by-anon_vma.patch
mm-rmap-rename-anon_vma_interval_tree_-params-and-use-pgoff_t.patch
mm-rmap-rename-anon_vma_interval_tree_-to-anon_rmap_tree_.patch
maintainers-move-mm-interval_treec-to-rmap-section.patch
mm-vma-introduce-and-use-vmg_pages-vmg__pgoff.patch
mm-vma-clean-up-anon_vma_compatible.patch
mm-vma-refactor-vmg_adjust_set_range-for-clarity.patch
mm-vma-minor-cleanup-of-expand_.patch
mm-introduce-and-use-linear_page_delta.patch
mm-vma-use-vma_start_pgoff-linear_page_index-in-mm-code.patch
mm-prefer-vma__pgoff-to-vma-vm_pgoff-in-kernel.patch
mm-vma-remove-duplicative-vma_pgoff_offset-helper.patch
mm-use-linear_page_-consistently.patch
mm-vma-introduce-vma_assert_can_modify.patch
mm-vma-add-and-use-vma__pgoff.patch
mm-vma-move-__install_special_mapping-to-vmac.patch
mm-vma-make-vma_set_range-static-drop-insert_vm_struct-decl.patch
mm-vma-update-vma_shrink-to-not-pass-start-pgoff-parameters.patch
mm-vma-update-vmg_adjust_set_range-to-offset-pgoff-instead.patch
mm-vma-slightly-rework-the-anonymous-check-in-__mmap_new_vma.patch
mm-vma-introduce-and-use-vma_set_pgoff.patch
mm-vma-correct-incorrect-vmah-inclusion.patch
mm-vma-use-guard-clauses-in-can_vma_merge_.patch
tools-testing-vma-default-vma-mm-flag-bits-to-64-bit.patch
tools-testing-vma-output-compared-expression-on-assert_.patch