From: Rik van Riel <riel@xxxxxxxxxxx> commit 12df140f0bdfae5dcfc81800970dd7f6f632e00c upstream. 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@xxxxxxxxxxxxxxxxxxxx Fixes: a88c76954804 ("mm: hugetlb: fix hugepage memory leak caused by wrong reserve count") Signed-off-by: Rik van Riel <riel@xxxxxxxxxxx> Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Cc: Glen McCready <gkmccready@xxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- mm/hugetlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2387,11 +2387,11 @@ struct page *alloc_huge_page(struct vm_a page = alloc_buddy_huge_page_with_mpol(h, vma, addr); if (!page) goto out_uncharge_cgroup; + spin_lock(&hugetlb_lock); if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) { SetPagePrivate(page); h->resv_huge_pages--; } - spin_lock(&hugetlb_lock); list_add(&page->lru, &h->hugepage_activelist); /* Fall through */ }
