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.
Link: https://lkml.kernel.org/r/20210115124942.46403-5-songmuchun@bytedance.com
Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
0eb2df2b56