Messages in this thread | | | Subject | Re: [PATCH mm-unstable v5 01/10] mm: add folio dtor and order setter functions | From | Muchun Song <> | Date | Wed, 7 Dec 2022 11:34:31 +0800 |
| |
> On Nov 30, 2022, at 06:50, Sidhartha Kumar <sidhartha.kumar@oracle.com> wrote: > > Add folio equivalents for set_compound_order() and set_compound_page_dtor(). > > Also remove extra new-lines introduced by mm/hugetlb: convert > move_hugetlb_state() to folios and mm/hugetlb_cgroup: convert > hugetlb_cgroup_uncharge_page() to folios. > > Suggested-by: Mike Kravetz <mike.kravetz@oracle.com> > Suggested-by: Muchun Song <songmuchun@bytedance.com> > Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com> > --- > include/linux/mm.h | 16 ++++++++++++++++ > mm/hugetlb.c | 4 +--- > 2 files changed, 17 insertions(+), 3 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index a48c5ad16a5e..2bdef8a5298a 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -972,6 +972,13 @@ static inline void set_compound_page_dtor(struct page *page, > page[1].compound_dtor = compound_dtor; > } > > +static inline void folio_set_compound_dtor(struct folio *folio, > + enum compound_dtor_id compound_dtor) > +{ > + VM_BUG_ON_FOLIO(compound_dtor >= NR_COMPOUND_DTORS, folio); > + folio->_folio_dtor = compound_dtor; > +} > + > void destroy_large_folio(struct folio *folio); > > static inline int head_compound_pincount(struct page *head) > @@ -987,6 +994,15 @@ static inline void set_compound_order(struct page *page, unsigned int order) > #endif > } > > +static inline void folio_set_compound_order(struct folio *folio, > + unsigned int order) > +{ > + folio->_folio_order = order; > +#ifdef CONFIG_64BIT > + folio->_folio_nr_pages = order ? 1U << order : 0;
It seems that you think the user could pass 0 to order. However, ->_folio_nr_pages and ->_folio_order fields are invalid for order-0 pages. You should not touch it. So this should be:
static inline void folio_set_compound_order(struct folio *folio, unsigned int order) { if (!folio_test_large(folio)) return;
folio->_folio_order = order; #ifdef CONFIG_64BIT folio->_folio_nr_pages = 1U << order; #endif }
If we can make sure all the users of folio_set_compound_order() should pass a non-order-0 page (it is true for now), then I suggest adding a VM_BUG_ON() here to catch unexpected users.
static inline void folio_set_compound_order(struct folio *folio, unsigned int order) { VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
folio->_folio_order = order; #ifdef CONFIG_64BIT folio->_folio_nr_pages = 1U << order; #endif }
Thanks.
> +#endif > +} > +
| |