+ mm-khugepaged-unmap-pte-before-releasing-vma-write-lock.patch added to mm-unstable branch

+ mm-khugepaged-unmap-pte-before-releasing-vma-write-lock.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/khugepaged: unmap pte before releasing vma write lock
has been added to the -mm mm-unstable branch.  Its filename is
     mm-khugepaged-unmap-pte-before-releasing-vma-write-lock.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-khugepaged-unmap-pte-before-releasing-vma-write-lock.patch

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

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------------------------------------------------------
From: "Nico Pache (Red Hat)" <nico.pache@linux.dev>
Subject: mm/khugepaged: unmap pte before releasing vma write lock
Date: Tue, 11 Aug 2026 06:48:38 -0600

We are currently dropping the anon_vma write lock before unmapping the
PTE.  Although this is safe, due to us still holding the mmap_write_lock,
its safer and less confusing to switch the order of these two operations.

Link: https://lore.kernel.org/20260811-khugepaged_pte_refactor-v4-6-ddac39d61c4a@linux.dev
Signed-off-by: Nico Pache (Red Hat) <nico.pache@linux.dev>
Suggested-by: David Hildenbrand <david@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Usama Arif <usama.arif@linux.dev>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/khugepaged.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/khugepaged.c~mm-khugepaged-unmap-pte-before-releasing-vma-write-lock
+++ a/mm/khugepaged.c
@@ -1546,10 +1546,10 @@ static enum scan_result collapse_huge_pa
 
 	result = SCAN_SUCCEED;
 out_up_write:
-	if (anon_vma_locked)
-		anon_vma_unlock_write(vma->anon_vma);
 	if (pte)
 		pte_unmap(pte);
+	if (anon_vma_locked)
+		anon_vma_unlock_write(vma->anon_vma);
 	mmap_write_unlock(mm);
 out_nolock:
 	if (folio)
_

Patches currently in -mm which might be from nico.pache@linux.dev are

mm-khugepaged-refactor-per-scan-state-clearing-into-collapse_control_init_scan.patch
mm-khugepaged-extract-reference-check-into-folio_pte_referenced-helper.patch
mm-khugepaged-introduce-a-count_collapse_event-helper.patch
mm-khugepaged-fix-outdated-comments.patch
mm-khugepaged-refactor-the-pte-state-checks-into-a-helper.patch
mm-khugepaged-unmap-pte-before-releasing-vma-write-lock.patch
mm-documentation-clarify-where-the-mthp-stats-live.patch