On Fri, May 20, 2022 at 02:31:24AM +0800, Chih-En Lin wrote: > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 8834e38c06a4..5dcbd7f6c361 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -221,6 +221,7 @@ struct page { > #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS > int _last_cpupid; > #endif > + pmd_t *cow_pte_owner; /* cow pte: pmd */ This is definitely the wrong place. I think it could replace _pt_pad_1, since it's a pointer to a PMD and so the bottom bit will definitely be clear.