The patch titled Subject: mm,hugetlb: take hugetlb_lock before decrementing h->resv_huge_pages has been added to the -mm mm-hotfixes-unstable branch. Its filename is mmhugetlb-take-hugetlb_lock-before-decrementing-h-resv_huge_pages.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Rik van Riel riel@surriel.com Subject: mm,hugetlb: take hugetlb_lock before decrementing h->resv_huge_pages Date: Mon, 17 Oct 2022 20:25:05 -0400

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 ---

mm/hugetlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/hugetlb.c~mmhugetlb-take-hugetlb_lock-before-decrementing-h-resv_huge_pages +++ a/mm/hugetlb.c @@ -2924,11 +2924,11 @@ 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_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 */ _

Patches currently in -mm which might be from riel@surriel.com are

mmhugetlb-take-hugetlb_lock-before-decrementing-h-resv_huge_pages.patch