Re: [PATCH v2 02/69] mm/hugetlb_vmemmap: Fix __hugetlb_vmemmap_optimize_folios()
From: Oscar Salvador <osalvador@suse.de>
Date: 2026-05-14 07:56:42
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On Wed, May 13, 2026 at 09:04:30PM +0800, Muchun Song wrote:
__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.
Fixes: 752fe17af693 ("mm/hugetlb: add pre-HVO framework")
Signed-off-by: Muchun Song <redacted>Acked-by: Oscar Salvador <osalvador@suse.de> did you observe any Ooops or malfunctioning or was just code reviewing? -- Oscar Salvador SUSE Labs