This patch add VM_BUG_ON_PAGE() for slab page, because _mapcount is an union with slab struct in struct page, avoid access _mapcount if this page is a slab page. Also remove the unneeded bracket. Signed-off-by: Yalin Wang --- include/linux/mm.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index b464611..a117527 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -449,7 +449,8 @@ static inline void page_mapcount_reset(struct page *page) static inline int page_mapcount(struct page *page) { - return atomic_read(&(page)->_mapcount) + 1; + VM_BUG_ON_PAGE(PageSlab(page), page); + return atomic_read(&page->_mapcount) + 1; } static inline int page_count(struct page *page) -- 2.1.3 {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I