[folded-merged] mm-mremap-check-remap-conditions-earlier-fix.patch removed from -mm tree

[folded-merged] mm-mremap-check-remap-conditions-earlier-fix.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/mremap: allow undocumented mremap() shrink behaviour
has been removed from the -mm tree.  Its filename was
     mm-mremap-check-remap-conditions-earlier-fix.patch

This patch was dropped because it was folded into mm-mremap-check-remap-conditions-earlier.patch

------------------------------------------------------
From: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Subject: mm/mremap: allow undocumented mremap() shrink behaviour
Date: Sun, 20 Jul 2025 11:41:48 +0100

It turns out that, in apparent contradiction to the man page, and at odds
with every other mremap() operation - we are allowed to specify an input
addr, old_len range that spans any number of VMAs and any number of gaps,
as long as we shrink that range to the point at which the new range spans
only one.

In order to accommodate this, adjust the remap validity check to account
for this.

Link: https://lkml.kernel.org/r/8fc92a38-c636-465e-9a2f-2c6ac9cb49b8@lucifer.local
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202507201002.69144b74-lkp@intel.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mremap.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/mm/mremap.c~mm-mremap-check-remap-conditions-earlier-fix
+++ a/mm/mremap.c
@@ -1339,11 +1339,18 @@ static int remap_is_valid(struct vma_rem
 			(vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)))
 		return -EINVAL;
 
+	/*
+	 * We permit crossing of boundaries for the range being unmapped due to
+	 * a shrink.
+	 */
+	if (vrm->remap_type == MREMAP_SHRINK)
+		old_len = new_len;
+
 	/* We can't remap across vm area boundaries */
 	if (old_len > vma->vm_end - addr)
 		return -EFAULT;
 
-	if (new_len <= old_len)
+	if (new_len == old_len)
 		return 0;
 
 	/* Need to be careful about a growing mapping */
_

Patches currently in -mm which might be from lorenzo.stoakes@oracle.com are

mm-vma-refactor-vma_modify_flags_name-to-vma_modify_name.patch
mm-mremap-perform-some-simple-cleanups.patch
mm-mremap-refactor-initial-parameter-sanity-checks.patch
mm-mremap-put-vma-check-and-prep-logic-into-helper-function.patch
mm-mremap-cleanup-post-processing-stage-of-mremap.patch
mm-mremap-use-an-explicit-uffd-failure-path-for-mremap.patch
mm-mremap-check-remap-conditions-earlier.patch
mm-mremap-move-remap_is_valid-into-check_prep_vma.patch
mm-mremap-clean-up-mlock-populate-behaviour.patch
mm-mremap-permit-mremap-move-of-multiple-vmas.patch
tools-testing-selftests-extend-mremap_test-to-test-multi-vma-mremap.patch
tools-testing-selftests-add-mremap-shrink-test-for-multiple-vmas.patch
tools-testing-selftests-test-mremap_dontunmap-on-multiple-vma-move.patch
tools-testing-selftests-explicitly-test-split-multi-vma-mremap-move.patch
docs-update-thp-documentation-to-clarify-sysfs-never-setting.patch
docs-update-thp-documentation-to-clarify-sysfs-never-setting-fix.patch
mm-mseal-always-define-vm_sealed.patch
mm-mseal-update-madvise-logic.patch
mm-mseal-small-cleanups.patch
mm-mseal-simplify-and-rename-vma-gap-check.patch
mm-mseal-rework-mseal-apply-logic.patch
maintainers-add-missing-percpu-internalh-file-to-per-cpu-section.patch
maintainers-add-missing-interval_treec-to-memory-mapping-section.patch
maintainers-add-missing-mm_sloth-file-thp-section.patch
maintainers-add-missing-mm_sloth-file-thp-section-fix.patch
maintainers-move-memremap-to-hotplug-section.patch
maintainers-add-missing-shrinker-files.patch
maintainers-add-missing-files-to-page-alloc-section.patch
maintainers-add-missing-zsmalloc-file.patch
maintainers-add-mm-misc-section-add-missing-files-to-misc-and-core.patch
maintainers-add-missing-file-to-cgroup-section.patch