On Wed, Nov 11, 2020 at 03:40:05PM -0500, Zi Yan wrote:
> From: Zi Yan <ziy@xxxxxxxxxx>
>
> It adds a new_order parameter to set new page order in page owner.
> It prepares for upcoming changes to support split huge page to any lower
> order.
>
> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
> ---
> include/linux/page_owner.h | 7 ++++---
> mm/huge_memory.c | 2 +-
> mm/page_alloc.c | 2 +-
> mm/page_owner.c | 6 +++---
> 4 files changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h
> index 3468794f83d2..215cbb159568 100644
> --- a/include/linux/page_owner.h
> +++ b/include/linux/page_owner.h
> @@ -31,10 +31,11 @@ static inline void set_page_owner(struct page *page,
> __set_page_owner(page, order, gfp_mask);
> }
>
> -static inline void split_page_owner(struct page *page, unsigned int nr)
> +static inline void split_page_owner(struct page *page, unsigned int nr,
> + unsigned int new_order)
> {
> if (static_branch_unlikely(&page_owner_inited))
> - __split_page_owner(page, nr);
> + __split_page_owner(page, nr, new_order);
> }
> static inline void copy_page_owner(struct page *oldpage, struct page *newpage)
> {
> @@ -60,7 +61,7 @@ static inline void set_page_owner(struct page *page,
> {
> }
> static inline void split_page_owner(struct page *page,
> - unsigned int order)
> + unsigned int nr, unsigned int new_order)
With the addition of the new argument it's a bit hard to understand
what the function is supposed to do. It seems like nr == page_order(page),
is it right? Maybe we can pass old_order and new_order? Or just the page
and the new order?
> {
> }
> static inline void copy_page_owner(struct page *oldpage, struct page *newpage)
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index f599f5b9bf7f..8b7d771ee962 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2459,7 +2459,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
>
> ClearPageCompound(head);
>
> - split_page_owner(head, nr);
> + split_page_owner(head, nr, 1);
>
> /* See comment in __split_huge_page_tail() */
> if (PageAnon(head)) {
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index d77220615fd5..a9eead0e091a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3284,7 +3284,7 @@ void split_page(struct page *page, unsigned int order)
>
> for (i = 1; i < (1 << order); i++)
> set_page_refcounted(page + i);
> - split_page_owner(page, 1 << order);
> + split_page_owner(page, 1 << order, 1);
> }
> EXPORT_SYMBOL_GPL(split_page);
>
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index b735a8eafcdb..2b7f7e9056dc 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -204,7 +204,7 @@ void __set_page_owner_migrate_reason(struct page *page, int reason)
> page_owner->last_migrate_reason = reason;
> }
>
> -void __split_page_owner(struct page *page, unsigned int nr)
> +void __split_page_owner(struct page *page, unsigned int nr, unsigned int new_order)
> {
> int i;
> struct page_ext *page_ext = lookup_page_ext(page);
> @@ -213,9 +213,9 @@ void __split_page_owner(struct page *page, unsigned int nr)
> if (unlikely(!page_ext))
> return;
>
> - for (i = 0; i < nr; i++) {
> + for (i = 0; i < nr; i += (1 << new_order)) {
> page_owner = get_page_owner(page_ext);
> - page_owner->order = 0;
> + page_owner->order = new_order;
> page_ext = page_ext_next(page_ext);
I believe there cannot be any leftovers because nr is always a power of 2.
Is it true? Converting nr argument to order (if it's possible) will make it obvious.
Other than that the patch looks good to me.
Thanks!
