From: Muchun Song songmuchun@bytedance.com Subject: mm: hugetlbfs: fix cannot migrate the fallocated HugeTLB page

If a new hugetlb page is allocated during fallocate it will not be marked as active (set_page_huge_active) which will result in a later isolate_huge_page failure when the page migration code would like to move that page. Such a failure would be unexpected and wrong.

Only export set_page_huge_active, just leave clear_page_huge_active as static. Because there are no external users.

Link: https://lkml.kernel.org/r/20210115124942.46403-3-songmuchun@bytedance.com Fixes: 70c3547e36f5 (hugetlbfs: add hugetlbfs_fallocate()) Signed-off-by: Muchun Song songmuchun@bytedance.com Acked-by: Michal Hocko mhocko@suse.com Reviewed-by: Mike Kravetz mike.kravetz@oracle.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 ---

fs/hugetlbfs/inode.c | 3 ++- include/linux/hugetlb.h | 2 ++ mm/hugetlb.c | 2 +- 3 files changed, 5 insertions(+), 2 deletions(-)

--- a/fs/hugetlbfs/inode.c~mm-hugetlbfs-fix-cannot-migrate-the-fallocated-hugetlb-page +++ a/fs/hugetlbfs/inode.c @@ -735,9 +735,10 @@ static long hugetlbfs_fallocate(struct f

mutex_unlock(&hugetlb_fault_mutex_table[hash]);

+ set_page_huge_active(page); /* * unlock_page because locked by add_to_page_cache() - * page_put due to reference from alloc_huge_page() + * put_page() due to reference from alloc_huge_page() */ unlock_page(page); put_page(page); --- a/include/linux/hugetlb.h~mm-hugetlbfs-fix-cannot-migrate-the-fallocated-hugetlb-page +++ a/include/linux/hugetlb.h @@ -770,6 +770,8 @@ static inline void huge_ptep_modify_prot } #endif

+void set_page_huge_active(struct page *page); + #else /* CONFIG_HUGETLB_PAGE */ struct hstate {};

--- a/mm/hugetlb.c~mm-hugetlbfs-fix-cannot-migrate-the-fallocated-hugetlb-page +++ a/mm/hugetlb.c @@ -1349,7 +1349,7 @@ bool page_huge_active(struct page *page) }

/* never called for tail page */ -static void set_page_huge_active(struct page *page) +void set_page_huge_active(struct page *page) { VM_BUG_ON_PAGE(!PageHeadHuge(page), page); SetPagePrivate(&page[1]); _