[merged mm-stable] mm-page_table_check-add-explicit-pmd_none-check-in-pte_clear_range.patch removed from -mm tree

[merged mm-stable] mm-page_table_check-add-explicit-pmd_none-check-in-pte_clear_range.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/page_table_check: add explicit pmd_none check in pte_clear_range
has been removed from the -mm tree.  Its filename was
     mm-page_table_check-add-explicit-pmd_none-check-in-pte_clear_range.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Ye Liu <liuye@kylinos.cn>
Subject: mm/page_table_check: add explicit pmd_none check in pte_clear_range
Date: Wed, 19 Aug 2026 10:55:15 +0800

In __page_table_check_pte_clear_range(), the condition to determine
whether to iterate over PTEs only checked pmd_bad() and pmd_leaf().  This
relies on the implicit assumption that pmd_none() is always a subset of
pmd_bad() on all architectures supporting PAGE_TABLE_CHECK.

While this assumption currently holds for x86_64, arm64, s390, riscv, and
powerpc, it is an architecture-dependent behavior that may not hold for
future architectures.  Add an explicit pmd_none() check to make the intent
clear and avoid calling pte_offset_map() on an empty PMD, which could lead
to undefined behavior.

Link: https://lore.kernel.org/20260819025516.2967199-1-ye.liu@linux.dev
Signed-off-by: Ye Liu <liuye@kylinos.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
---

 mm/page_table_check.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/page_table_check.c~mm-page_table_check-add-explicit-pmd_none-check-in-pte_clear_range
+++ a/mm/page_table_check.c
@@ -278,7 +278,7 @@ void __page_table_check_pte_clear_range(
 	if (&init_mm == mm)
 		return;
 
-	if (!pmd_bad(pmd) && !pmd_leaf(pmd)) {
+	if (!pmd_none(pmd) && !pmd_bad(pmd) && !pmd_leaf(pmd)) {
 		pte_t *ptep = pte_offset_map(&pmd, addr);
 		unsigned long i;
 
_

Patches currently in -mm which might be from liuye@kylinos.cn are

mm-vmalloc-group-xa_init-with-vbq-field-initializations.patch
mm-vmalloc-extract-vmap_insert_free_area-helper.patch
mm-vmalloc-extract-show_busy_info-from-vmalloc_info_show.patch
mm-vmalloc-fix-vmalloc_dump_obj-address-alignment-for-last-page-lookups.patch
mm-vmalloc-fix-vmalloc_dump_obj-cross-zone-va-lookup.patch