From: Muchun Song songmuchun@bytedance.com Subject: mm: hugetlb: remove VM_BUG_ON_PAGE from page_huge_active

The page_huge_active() can be called from scan_movable_pages() which do not hold a reference count to the HugeTLB page. So when we call page_huge_active() from scan_movable_pages(), the HugeTLB page can be freed parallel. Then we will trigger a BUG_ON which is in the page_huge_active() when CONFIG_DEBUG_VM is enabled. Just remove the VM_BUG_ON_PAGE.

Link: https://lkml.kernel.org/r/20210115124942.46403-6-songmuchun@bytedance.com Fixes: 7e1f049efb86 ("mm: hugetlb: cleanup using paeg_huge_active()") 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 ---

mm/hugetlb.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/mm/hugetlb.c~mm-hugetlb-remove-vm_bug_on_page-from-page_huge_active +++ a/mm/hugetlb.c @@ -1361,8 +1361,7 @@ struct hstate *size_to_hstate(unsigned l */ bool page_huge_active(struct page *page) { - VM_BUG_ON_PAGE(!PageHuge(page), page); - return PageHead(page) && PagePrivate(&page[1]); + return PageHeadHuge(page) && PagePrivate(&page[1]); }

/* never called for tail page */ _