From 23fac055c21176f66ed453394b533bdfc00f7fba Mon Sep 17 00:00:00 2001 From: Hongfu Li Date: Fri, 18 Sep 2026 10:56:11 +0800 Subject: [PATCH] mm/hugetlb_cgroup: move per-node usage on cgroup reparenting hugetlb_cgroup_css_offline() hands the folios of a dying cgroup over to its parent with hugetlb_cgroup_move_parent(), which moves the page_counter charges and the hugetlb_cgroup pointer of the folio but not its per-node usage. The parent's hugetlb..numa_stat is short by that usage while they are charged, and underflows once they are freed, exposing incorrect per-node usage values to userspace. Move the per-node usage to the parent as well. The folios keep their node here, so only the cgroup which holds the usage changes. Link: https://lore.kernel.org/20260918-for-hugetlb-charge-v2-2-2b6d8c2bdc36@kylinos.cn Fixes: f47761999052 ("hugetlb: add hugetlb.*.numa_stat file") Signed-off-by: Hongfu Li Signed-off-by: Andrew Morton Acked-by: Muchun Song Cc: Colin Ian King Cc: David Hildenbrand Cc: Kees Cook Cc: Mina Almasry Cc: Oscar Salvador Cc: Shakeel Butt Cc: --- mm/hugetlb_cgroup.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c index 7cf7c18119b4..3fb41311e4c7 100644 --- a/mm/hugetlb_cgroup.c +++ b/mm/hugetlb_cgroup.c @@ -241,6 +241,8 @@ static void hugetlb_cgroup_move_parent(int idx, struct hugetlb_cgroup *h_cg, /* Take the pages off the local counter */ page_counter_cancel(counter, nr_pages); + hugetlb_cgroup_move_usage(h_cg, parent, folio, folio); + set_hugetlb_cgroup(folio, parent); out: return;