On Wed, Nov 04, 2015 at 04:00:59PM +0100, Vlastimil Babka wrote:
> The page_owner mechanism stores gfp_flags of an allocation and stack trace
> that lead to it. During page migration, the original information is
> essentially replaced by the allocation of free page as the migration target.
> Arguably this is less useful and might lead to all the page_owner info for
> migratable pages gradually converge towards compaction or numa balancing
> migrations. It has also lead to inaccuracies such as one fixed by commit
> e2cfc91120fa ("mm/page_owner: set correct gfp_mask on page_owner").
>
> This patch thus introduces copying the page_owner info during migration.
> However, since the fact that the page has been migrated from its original
> place might be useful for debugging, the next patch will introduce a way to
> track that information as well.
>
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
> ---
> include/linux/page_owner.h | 10 +++++++++-
> mm/migrate.c | 2 ++
> mm/page_owner.c | 16 ++++++++++++++++
> 3 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h
> index 8e2eb15..6440daa 100644
> --- a/include/linux/page_owner.h
> +++ b/include/linux/page_owner.h
> @@ -11,6 +11,7 @@ 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);
> +extern void __copy_page_owner(struct page *oldpage, struct page *newpage);
>
> static inline void reset_page_owner(struct page *page, unsigned int order)
> {
> @@ -32,6 +33,11 @@ static inline gfp_t get_page_owner_gfp(struct page *page)
> else
> return 0;
> }
> +static inline void copy_page_owner(struct page *oldpage, struct page *newpage)
> +{
> + if (static_branch_unlikely(&page_owner_inited))
> + __copy_page_owner(oldpage, newpage);
> +}
> #else
> static inline void reset_page_owner(struct page *page, unsigned int order)
> {
> @@ -44,6 +50,8 @@ static inline gfp_t get_page_owner_gfp(struct page *page)
> {
> return 0;
> }
> -
> +static inline void copy_page_owner(struct page *oldpage, struct page *newpage)
> +{
> +}
> #endif /* CONFIG_PAGE_OWNER */
> #endif /* __LINUX_PAGE_OWNER_H */
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 1ae0113..9f82e03 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -38,6 +38,7 @@
> #include <linux/balloon_compaction.h>
> #include <linux/mmu_notifier.h>
> #include <linux/page_idle.h>
> +#include <linux/page_owner.h>
>
> #include <asm/tlbflush.h>
>
> @@ -775,6 +776,7 @@ static int move_to_new_page(struct page *newpage, struct page *page,
> set_page_memcg(page, NULL);
> if (!PageAnon(page))
> page->mapping = NULL;
> + copy_page_owner(page, newpage);
> }
> return rc;
> }
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index 7664b85..7ebd3d0 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -84,6 +84,22 @@ gfp_t __get_page_owner_gfp(struct page *page)
> return page_ext->gfp_mask;
> }
>
> +void __copy_page_owner(struct page *oldpage, struct page *newpage)
> +{
> + struct page_ext *old_ext = lookup_page_ext(oldpage);
> + struct page_ext *new_ext = lookup_page_ext(newpage);
> + int i;
> +
> + new_ext->order = old_ext->order;
> + new_ext->gfp_mask = old_ext->gfp_mask;
> + new_ext->nr_entries = old_ext->nr_entries;
> +
> + for (i = 0; i < ARRAY_SIZE(new_ext->trace_entries); i++)
> + new_ext->trace_entries[i] = old_ext->trace_entries[i];
> +
> + __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
> +}
> +
Need to clear PAGE_EXT_OWNER bit in oldppage.
Thanks.
> static ssize_t
> print_page_owner(char __user *buf, size_t count, unsigned long pfn,
> struct page *page, struct page_ext *page_ext)
> --
> 2.6.2
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@xxxxxxxxx. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>