diff options
| -rw-r--r-- | arch/powerpc/mm/hugetlbpage.c | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c index 78b14abded65..a618ef01bfad 100644 --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -385,12 +385,23 @@ follow_huge_pmd(struct mm_struct *mm, unsigned long address, return NULL; } +static inline void get_huge_page_tail(struct page *page) +{ + /* + * __split_huge_page_refcount() cannot run + * from under us. + */ + VM_BUG_ON(page_mapcount(page) < 0); + VM_BUG_ON(atomic_read(&page->_count) != 0); + atomic_inc(&page->_mapcount); +} + static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr, unsigned long end, int write, struct page **pages, int *nr) { unsigned long mask; unsigned long pte_end; - struct page *head, *page; + struct page *head, *page, *tail; pte_t pte; int refs; @@ -413,6 +424,7 @@ static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long add head = pte_page(pte); page = head + ((addr & (sz-1)) >> PAGE_SHIFT); + tail = page; do { VM_BUG_ON(compound_head(page) != head); pages[*nr] = page; @@ -431,6 +443,16 @@ static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long add *nr -= refs; while (refs--) put_page(head); + } else { + /* + * Any tail page need their mapcount reference taken + * before we return. + */ + while (refs--) { + if (PageTail(tail)) + get_huge_page_tail(tail); + tail++; + } } return 1; |