From e95d29c5df84f19881cd30b491fc81aa98f44b45 Mon Sep 17 00:00:00 2001 From: Ackerley Tng Date: Wed, 9 Sep 2026 10:11:01 -0700 Subject: [PATCH] mm: hugetlb: drop refcount before freeing on memcg charge failure When mem_cgroup_charge_hugetlb(folio, gfp) returns -ENOMEM, the folio has its refcount set to 1 via folio_ref_unfreeze(folio, 1). The error path calls free_huge_folio(folio) directly, which expects a refcount of 0. Hence, VM_BUG_ON_FOLIO(folio_ref_count(folio), folio) is triggered. Even with CONFIG_DEBUG_VM disabled, returning a folio with refcount 1 to the freelist can corrupt allocator state later. Use folio_put(folio) instead of free_huge_folio(folio) to properly drop the reference before freeing it. Link: https://lore.kernel.org/20260909-hugetlb-alloc-folio-memcg-charge-error-handling-v2-2-4b4a8a19a7f7@google.com Fixes: 991135774c0e ("memcg/hugetlb: introduce mem_cgroup_charge_hugetlb") Signed-off-by: Ackerley Tng Signed-off-by: Andrew Morton Reviewed-by: Muchun Song Reviewed-by: Joshua Hahn Cc: Alex Shi Cc: David Hildenbrand Cc: David Rientjes Cc: Dongliang Mu Cc: Frank van der Linden Cc: Hongxiang Lou Cc: James Houghton Cc: Johannes Weiner Cc: Jonathan Corbet Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Ma Wupeng Cc: Miaohe Lin Cc: Michal Hocko Cc: Mike Rapoport Cc: Nhat Pham Cc: Oscar Salvador Cc: Peter Xu Cc: Roman Gushchin Cc: Shakeel Butt Cc: Suren Baghdasaryan Cc: Vishal Annapurve Cc: Vlastimil Babka Cc: Yanteng Si Cc: --- mm/hugetlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index a16d04aae619..cdb7d8df666a 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2917,7 +2917,7 @@ struct folio *hugetlb_alloc_folio(struct hstate *h, lruvec_stat_mod_folio(folio, NR_HUGETLB, nr_pages); if (ret == -ENOMEM) { - free_huge_folio(folio); + folio_put(folio); /* * Skip uncharging hugetlb_cgroup since the charges * were committed to the folio and freeing the folio