[merged mm-hotfixes-stable] mm-madvise-preserve-vma_softdirty_bit-when-changing-anonymous-names.patch removed from -mm tree

[merged mm-hotfixes-stable] mm-madvise-preserve-vma_softdirty_bit-when-changing-anonymous-names.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/madvise: preserve VMA_SOFTDIRTY_BIT when changing anonymous names
has been removed from the -mm tree.  Its filename was
     mm-madvise-preserve-vma_softdirty_bit-when-changing-anonymous-names.patch

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

------------------------------------------------------
From: "David Hildenbrand (Arm)" <david@kernel.org>
Subject: mm/madvise: preserve VMA_SOFTDIRTY_BIT when changing anonymous names
Date: Fri, 23 Oct 2026 14:47:29 +0100

When changing the anonymous VMA name, madvise_update_vma() calls
vma_modify_name() to possibly merge with adjacent VMAs. We don't call
vma_modify_flags() and consequently don't obtain the new VMA flags.

Later in the function we update the VMA flags to the stale new_vma_flags
we obtained before. This can result in us losing the VMA_SOFTDIRTY_BIT
flag set on a VMA we just merged with.

There is no need to update the VMA flags at all, so just exit early. This
skips calling khugepaged_enter_vma(), but since the flags didn't change
this is fine.

[ljs@kernel.org: minor edit of commit message, rebased]
Link: https://lore.kernel.org/20261023-fix-vma-atomic-v1-3-8ff4fae1fc85@kernel.org
Fixes: 9a10064f5625 ("mm: add a field to store names for private anonymous memory")
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Tested-by: Gregory Price (Meta) <gourry@gourry.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Jann Horn <jannh@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: SJ Park <sj@kernel.org>
Cc: Kees Cook <kees@kernel.org>
Cc: Colin Cross <ccross@google.com>
Cc: <stable@vger.kernel.org>
---

 mm/madvise.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/mm/madvise.c~mm-madvise-preserve-vma_softdirty_bit-when-changing-anonymous-names
+++ a/mm/madvise.c
@@ -177,6 +177,9 @@ static int madvise_update_vma(vm_flags_t
 
 	/* vm_flags is protected by the mmap_lock held in write mode. */
 	vma_start_write(vma);
+	if (set_new_anon_name)
+		return replace_anon_vma_name(vma, anon_name);
+
 	vma_overwrite_flags(vma, new_vma_flags);
 	/*
 	 * If the vma become good for khugepaged to scan,
@@ -186,9 +189,6 @@ static int madvise_update_vma(vm_flags_t
 	if (vma_flags_test(&new_vma_flags, VMA_HUGEPAGE_BIT))
 		khugepaged_enter_vma(vma, vma_flags_to_legacy(new_vma_flags));
 
-	if (set_new_anon_name)
-		return replace_anon_vma_name(vma, anon_name);
-
 	return 0;
 }
 
_

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

mm-memory-failure-fix-folio-refcount-leak-and-min_order_for_split-locking.patch