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My bad for not noticing when the bug was introduced. > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index a6bad1f686c5..082ed643020b 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -2047,13 +2047,16 @@ static int gather_surplus_pages(struct hstate *h, long delta) > > /* Free the needed pages to the hugetlb pool */ > list_for_each_entry_safe(page, tmp, &surplus_list, lru) { > + int zeroed; > + > if ((--needed) < 0) > break; > /* > * This page is now managed by the hugetlb allocator and has > * no users -- drop the buddy allocator's reference. > */ > - VM_BUG_ON_PAGE(!put_page_testzero(page), page); > + zeroed = put_page_testzero(page); > + VM_BUG_ON_PAGE(!zeroed, page); > enqueue_huge_page(h, page); I was wondering why this was not causing any problems. We are putting the hugetlb page on the free list with a count of 1. There is no check in the enqueue code. When we dequeue the page, set_page_refcounted() is used to set the count to 1 without looking at the current value. And, all the other VM_DEBUG macros are off so we mostly do not notice the bug. Thanks again, Reviewed-by: Mike Kravetz -- Mike Kravetz > } > free: >