From 6e25c6a9c7eff141ecfc966ecdb7801db2a8810e Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Fri, 12 Jun 2026 11:58:46 +0800 Subject: [PATCH] mm/hugetlb_vmemmap: fix __hugetlb_vmemmap_optimize_folios() __hugetlb_vmemmap_optimize_folios() uses incorrect arguments when handling bootmem HugeTLB folios. The section number passed to register_page_bootmem_memmap() is derived from the vmemmap virtual address of folio->page instead of the folio PFN, so the bootmem memmap metadata can be registered against the wrong section. The helper is also given HUGETLB_VMEMMAP_RESERVE_SIZE even though it expects a page count, not a size in bytes. In addition, the write-protect range is based on pages_per_huge_page(h), which does not cover the full HugeTLB vmemmap area and can leave part of the shared tail vmemmap mapping writable. Fix the section lookup to use folio_pfn(folio), use HUGETLB_VMEMMAP_RESERVE_PAGES when registering the reserved memmap pages, and use hugetlb_vmemmap_size(h) for the write-protect range. Link: https://lore.kernel.org/20260612035903.2468601-3-songmuchun@bytedance.com Fixes: 752fe17af693 ("mm/hugetlb: add pre-HVO framework") Signed-off-by: Muchun Song Acked-by: Oscar Salvador Reviewed-by: Frank van der Linden Cc: "Aneesh Kumar K.V" Cc: David Hildenbrand Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Mike Rapoport (Microsoft) Cc: Nicholas Piggin Cc: Oscar Salvador (SUSE) Cc: "Ritesh Harjani (IBM)" Cc: Usama Arif Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton --- mm/hugetlb_vmemmap.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index c713c0d2593a..ea6af85bfec1 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -635,12 +635,12 @@ static void __hugetlb_vmemmap_optimize_folios(struct hstate *h, * mirrored tail page structs RO. */ spfn = (unsigned long)&folio->page; - epfn = spfn + pages_per_huge_page(h); + epfn = spfn + hugetlb_vmemmap_size(h); vmemmap_wrprotect_hvo(spfn, epfn, folio_nid(folio), HUGETLB_VMEMMAP_RESERVE_SIZE); - register_page_bootmem_memmap(pfn_to_section_nr(spfn), + register_page_bootmem_memmap(pfn_to_section_nr(folio_pfn(folio)), &folio->page, - HUGETLB_VMEMMAP_RESERVE_SIZE); + HUGETLB_VMEMMAP_RESERVE_PAGES); continue; }