On Wed, Jul 15, 2015 at 03:33:59PM +0900, Joonsoo Kim wrote:
> Currently, we set wrong gfp_mask to page_owner info in case of
> isolated freepage by compaction and split page. It causes incorrect
> mixed pageblock report that we can get from '/proc/pagetypeinfo'.
> This metric is really useful to measure fragmentation effect so
> should be accurate. This patch fixes it by setting correct
> information.
>
> Without this patch, after kernel build workload is finished, number
> of mixed pageblock is 112 among roughly 210 movable pageblocks.
>
> But, with this fix, output shows that mixed pageblock is just 57.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> ---
> include/linux/page_owner.h | 13 +++++++++++++
> mm/page_alloc.c | 8 +++++---
> mm/page_owner.c | 7 +++++++
> 3 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h
> index b48c347..cacaabe 100644
> --- a/include/linux/page_owner.h
> +++ b/include/linux/page_owner.h
> @@ -8,6 +8,7 @@ extern struct page_ext_operations page_owner_ops;
> extern void __reset_page_owner(struct page *page, unsigned int order);
> extern void __set_page_owner(struct page *page,
> unsigned int order, gfp_t gfp_mask);
> +extern gfp_t __get_page_owner_gfp(struct page *page);
>
> static inline void reset_page_owner(struct page *page, unsigned int order)
> {
> @@ -25,6 +26,14 @@ static inline void set_page_owner(struct page *page,
>
> __set_page_owner(page, order, gfp_mask);
> }
> +
> +static inline gfp_t get_page_owner_gfp(struct page *page)
> +{
> + if (likely(!page_owner_inited))
> + return 0;
> +
> + return __get_page_owner_gfp(page);
> +}
> #else
> static inline void reset_page_owner(struct page *page, unsigned int order)
> {
> @@ -33,6 +42,10 @@ static inline void set_page_owner(struct page *page,
> unsigned int order, gfp_t gfp_mask)
> {
> }
> +static inline gfp_t get_page_owner_gfp(struct page *page)
> +{
> + return 0;
> +}
>
> #endif /* CONFIG_PAGE_OWNER */
> #endif /* __LINUX_PAGE_OWNER_H */
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 70d6a85..3ce3ec2 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1957,6 +1957,7 @@ void free_hot_cold_page_list(struct list_head *list, bool cold)
> void split_page(struct page *page, unsigned int order)
> {
> int i;
> + gfp_t gfp_mask;
>
> VM_BUG_ON_PAGE(PageCompound(page), page);
> VM_BUG_ON_PAGE(!page_count(page), page);
> @@ -1970,10 +1971,11 @@ void split_page(struct page *page, unsigned int order)
> split_page(virt_to_page(page[0].shadow), order);
> #endif
>
> - set_page_owner(page, 0, 0);
> + gfp_mask = get_page_owner_gfp(page);
> + set_page_owner(page, 0, gfp_mask);
> for (i = 1; i < (1 << order); i++) {
> set_page_refcounted(page + i);
> - set_page_owner(page + i, 0, 0);
> + set_page_owner(page + i, 0, gfp_mask);
> }
> }
> EXPORT_SYMBOL_GPL(split_page);
> @@ -2003,7 +2005,7 @@ int __isolate_free_page(struct page *page, unsigned int order)
> zone->free_area[order].nr_free--;
> rmv_page_order(page);
>
> - set_page_owner(page, order, 0);
> + set_page_owner(page, order, __GFP_MOVABLE);
It seems the reason why __GFP_MOVABLE is okay is that __isolate_free_page
works on a free page on MIGRATE_MOVABLE|MIGRATE_CMA's pageblock. But if we
break the assumption in future, here is broken again?
Please put the comment here to cause it.
Otherwise, Good spot!
Reviewed-by: Minchan Kim <minchan@xxxxxxxxxx>
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