Re: [PATCH 1/1] mm/hugetlb: keep max_huge_pages when dissolving surplus folios

[Muchun Song]

> On Aug 14, 2026, at 16:30, Longlong Xia <xialonglong2025@xxxxxxx> wrote:
> 
> From: Longlong Xia <xialonglong@xxxxxxxxxx>
> 
> dissolve_free_hugetlb_folio() can remove a free folio as surplus when
> its node has surplus pages.  In that case remove_hugetlb_folio()
> decrements both nr_huge_pages and surplus_huge_pages, leaving the
> persistent pool size unchanged.
> 
> Updating max_huge_pages as if a persistent folio had been removed can
> therefore corrupt the persistent pool target and underflow it when
> max_huge_pages is zero.  Keep max_huge_pages unchanged for surplus
> folios, including the vmemmap restoration rollback path.
> 
> Fixes: cb402bbdabca ("mm/hugetlb: fix surplus pages in dissolve_free_huge_page()")
> Assisted-by: Codex:gpt-5.6-sol
> Signed-off-by: Longlong Xia <xialonglong@xxxxxxxxxx>

Reviewed-by: Muchun Song <muchun.song@xxxxxxxxx>

Thanks.