Re: [PATCH v3 14/16] mm: remove is_hugetlb_entry_[migration, hwpoisoned]()

[Andrew Morton]

On Thu, 27 Nov 2025 17:45:17 +0000 Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx> wrote:

> Hi Andrew,
> 
> Please apply this fix.
> 

The offending patch is in mm-stable now, so I'll do this as a
hey-git-made-me-add-a-bisection-hole commit.


From: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Subject: fs/proc/task_mmu.c: fix make_uffd_wp_huge_pte() huge pte handling
Date: Thu, 27 Nov 2025 17:45:17 +0000

make_uffd_wp_huge_pte() should return after handling a huge_pte_none()
pte.

Link: https://lkml.kernel.org/r/66178124-ebdf-4e23-b8ca-ed3eb8030c81@lucifer.local
Fixes: 03bfbc3ad6e4 ("mm: remove is_hugetlb_entry_[migration, hwpoisoned]()")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Reported-by: Vlastimil Babka <vbabka@xxxxxxx>
Closes: https://lkml.kernel.org/r/dc483db3-be4d-45f7-8b40-a28f5d8f5738@xxxxxxx
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 fs/proc/task_mmu.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/fs/proc/task_mmu.c~fs-proc-task_mmuc-fix-make_uffd_wp_huge_pte-huge-pte-handling
+++ a/fs/proc/task_mmu.c
@@ -2500,9 +2500,11 @@ static void make_uffd_wp_huge_pte(struct
 	const unsigned long psize = huge_page_size(hstate_vma(vma));
 	softleaf_t entry;
 
-	if (huge_pte_none(ptent))
+	if (huge_pte_none(ptent)) {
 		set_huge_pte_at(vma->vm_mm, addr, ptep,
 				make_pte_marker(PTE_MARKER_UFFD_WP), psize);
+		return;
+	}
 
 	entry = softleaf_from_pte(ptent);
 	if (softleaf_is_hwpoison(entry) || softleaf_is_marker(entry))
_