Messages in this thread | | | Date | Mon, 17 Oct 2022 19:05:48 -0700 | From | Mike Kravetz <> | Subject | Re: [PATCH] mm,hugetlb: take hugetlb_lock before decrementing h->resv_huge_pages |
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On 10/17/22 20:25, Rik van Riel wrote: > 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. > > Fixes: a88c76954804 ("mm: hugetlb: fix hugepage memory leak caused by wrong reserve count") > Cc: stable@kernel.org > 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: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Rik van Riel <riel@surriel.com> > --- > mm/hugetlb.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-)
Thanks Rik! That case did slip through the cracks.
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> -- Mike Kravetz
> > 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 */ > -- > 2.37.2 > >
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