+ mm-vma-introduce-and-use-vmg_pages-vmg__pgoff.patch added to mm-new branch

+ mm-vma-introduce-and-use-vmg_pages-vmg__pgoff.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/vma: introduce and use vmg_pages(), vmg_[start, end]_pgoff()
has been added to the -mm mm-new branch.  Its filename is
     mm-vma-introduce-and-use-vmg_pages-vmg__pgoff.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vma-introduce-and-use-vmg_pages-vmg__pgoff.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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Lorenzo Stoakes <ljs@kernel.org>
Subject: mm/vma: introduce and use vmg_pages(), vmg_[start, end]_pgoff()
Date: Fri, 10 Jul 2026 21:16:54 +0100

In the VMA logic we often need to determine the number of pages in the
specified merge range, as well as the start and end page offsets of that
range.

Introduce and use helpers for these purposes.

No functional change intended.

Link: https://lore.kernel.org/20260710-b4-pre-scalable-cow-v2-13-2a5aa403d977@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 |   11 ++++-------
 mm/vma.h |   17 +++++++++++++++++
 2 files changed, 21 insertions(+), 7 deletions(-)

--- a/mm/vma.c~mm-vma-introduce-and-use-vmg_pages-vmg__pgoff
+++ a/mm/vma.c
@@ -197,11 +197,9 @@ static void init_multi_vma_prep(struct v
  */
 static bool can_vma_merge_before(struct vma_merge_struct *vmg)
 {
-	pgoff_t pglen = PHYS_PFN(vmg->end - vmg->start);
-
 	if (is_mergeable_vma(vmg, /* merge_next = */ true) &&
 	    is_mergeable_anon_vma(vmg, /* merge_next = */ true)) {
-		if (vmg->next->vm_pgoff == vmg->pgoff + pglen)
+		if (vmg_end_pgoff(vmg) == vma_start_pgoff(vmg->next))
 			return true;
 	}
 
@@ -221,7 +219,7 @@ static bool can_vma_merge_after(struct v
 {
 	if (is_mergeable_vma(vmg, /* merge_next = */ false) &&
 	    is_mergeable_anon_vma(vmg, /* merge_next = */ false)) {
-		if (vmg->prev->vm_pgoff + vma_pages(vmg->prev) == vmg->pgoff)
+		if (vma_end_pgoff(vmg->prev) == vmg_start_pgoff(vmg))
 			return true;
 	}
 	return false;
@@ -759,7 +757,7 @@ static int commit_merge(struct vma_merge
 	 */
 	vma_adjust_trans_huge(vma, vmg->start, vmg->end,
 			      vmg->__adjust_middle_start ? vmg->middle : NULL);
-	vma_set_range(vma, vmg->start, vmg->end, vmg->pgoff);
+	vma_set_range(vma, vmg->start, vmg->end, vmg_start_pgoff(vmg));
 	vmg_adjust_set_range(vmg);
 	vma_iter_store_overwrite(vmg->vmi, vmg->target);
 
@@ -962,8 +960,7 @@ static __must_check struct vm_area_struc
 		 *    middle     next
 		 * shrink/delete extend
 		 */
-
-		pgoff_t pglen = PHYS_PFN(vmg->end - vmg->start);
+		const pgoff_t pglen = vmg_pages(vmg);
 
 		VM_WARN_ON_VMG(!merge_right, vmg);
 		/* If we are offset into a VMA, then prev must be middle. */
--- a/mm/vma.h~mm-vma-introduce-and-use-vmg_pages-vmg__pgoff
+++ a/mm/vma.h
@@ -230,6 +230,23 @@ static inline bool vmg_nomem(struct vma_
 	return vmg->state == VMA_MERGE_ERROR_NOMEM;
 }
 
+static inline pgoff_t vmg_start_pgoff(const struct vma_merge_struct *vmg)
+{
+	return vmg->pgoff;
+}
+
+static inline pgoff_t vmg_pages(const struct vma_merge_struct *vmg)
+{
+	const unsigned long size = vmg->end - vmg->start;
+
+	return size >> PAGE_SHIFT;
+}
+
+static inline pgoff_t vmg_end_pgoff(const struct vma_merge_struct *vmg)
+{
+	return vmg_start_pgoff(vmg) + vmg_pages(vmg);
+}
+
 /* Assumes addr >= vma->vm_start. */
 static inline pgoff_t vma_pgoff_offset(struct vm_area_struct *vma,
 				       unsigned long addr)
_

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