Messages in this thread | | | Subject | Re: [PATCH 5/6] mm: hugetlb: fix a race between isolating and freeing page | From | Mike Kravetz <> | Date | Mon, 4 Jan 2021 17:42:58 -0800 |
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On 1/3/21 10:58 PM, Muchun Song wrote: > There is a race between isolate_huge_page() and __free_huge_page(). > > CPU0: CPU1: > > if (PageHuge(page)) > put_page(page) > __free_huge_page(page) > spin_lock(&hugetlb_lock) > update_and_free_page(page) > set_compound_page_dtor(page, > NULL_COMPOUND_DTOR) > spin_unlock(&hugetlb_lock) > isolate_huge_page(page) > // trigger BUG_ON > VM_BUG_ON_PAGE(!PageHead(page), page) > spin_lock(&hugetlb_lock) > page_huge_active(page) > // trigger BUG_ON > VM_BUG_ON_PAGE(!PageHuge(page), page) > spin_unlock(&hugetlb_lock) > > When we isolate a HugeTLB page on CPU0. Meanwhile, we free it to the > buddy allocator on CPU1. Then, we can trigger a BUG_ON on CPU0. Because > it is already freed to the buddy allocator. > > Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage") > Signed-off-by: Muchun Song <songmuchun@bytedance.com> > --- > mm/hugetlb.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-)
Thanks!
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
-- Mike Kravetz
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