From: Rik van Riel riel@surriel.com
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@imladris.surriel.com Fixes: a88c76954804 ("mm: hugetlb: fix hugepage memory leak caused by wrong reserve count") Signed-off-by: Rik van Riel riel@surriel.com Reviewed-by: Mike Kravetz mike.kravetz@oracle.com Cc: Naoya Horiguchi n-horiguchi@ah.jp.nec.com Cc: Glen McCready gkmccready@meta.com Cc: Mike Kravetz mike.kravetz@oracle.com Cc: Muchun Song songmuchun@bytedance.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Mike Kravetz mike.kravetz@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/hugetlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2089,11 +2089,11 @@ 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_move(&page->lru, &h->hugepage_activelist); /* Fall through */ }