From 12df140f0bdfae5dcfc81800970dd7f6f632e00c Mon Sep 17 00:00:00 2001 From: Rik van Riel Date: Mon, 17 Oct 2022 20:25:05 -0400 Subject: [PATCH] mm,hugetlb: take hugetlb_lock before decrementing h->resv_huge_pages The h->*_huge_pages counters are protected by the hugetlb_lock, but alloc_huge_page has a corner case where it can decrement the counter outside of the lock. This could lead to a corrupted value of h->resv_huge_pages, which we have observed on our systems. Take the hugetlb_lock before decrementing h->resv_huge_pages to avoid a potential race. Link: https://lkml.kernel.org/r/20221017202505.0e6a4fcd@imladris.surriel.com Fixes: a88c76954804 ("mm: hugetlb: fix hugepage memory leak caused by wrong reserve count") Signed-off-by: Rik van Riel Reviewed-by: Mike Kravetz Cc: Naoya Horiguchi Cc: Glen McCready Cc: Mike Kravetz Cc: Muchun Song Cc: Signed-off-by: Andrew Morton --- mm/hugetlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index b586cdd75930..dede0337c07c 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2924,11 +2924,11 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, page = alloc_buddy_huge_page_with_mpol(h, vma, addr); if (!page) goto out_uncharge_cgroup; + spin_lock_irq(&hugetlb_lock); if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) { SetHPageRestoreReserve(page); h->resv_huge_pages--; } - spin_lock_irq(&hugetlb_lock); list_add(&page->lru, &h->hugepage_activelist); set_page_refcounted(page); /* Fall through */