[PATCH v2 4/7] mm/page_owner: introduce split_page_owner and replace manual handling

js1304
2016-05-26T02:39:26Z

From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

split_page() calls set_page_owner() to set up page_owner to each pages.
But, it has a drawback that head page and the others have different
stacktrace because callsite of set_page_owner() is slightly differnt.
To avoid this problem, this patch copies head page's page_owner to
the others. It needs to introduce new function, split_page_owner() but
it also remove the other function, get_page_owner_gfp() so looks good
to do.

Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
include/linux/page_owner.h | 12 +++++-------
mm/page_alloc.c | 8 ++------
mm/page_owner.c | 14 +++++++-------
3 files changed, 14 insertions(+), 20 deletions(-)

diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h
index 46f1b93..30583ab 100644
--- a/include/linux/page_owner.h
+++ b/include/linux/page_owner.h
@@ -10,7 +10,7 @@ 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);
+extern void __split_page_owner(struct page *page, unsigned int order);
extern void __copy_page_owner(struct page *oldpage, struct page *newpage);
extern void __set_page_owner_migrate_reason(struct page *page, int reason);
extern void __dump_page_owner(struct page *page);
@@ -28,12 +28,10 @@ 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)
+static inline void split_page_owner(struct page *page, unsigned int order)
{
if (static_branch_unlikely(&page_owner_inited))
- return __get_page_owner_gfp(page);
- else
- return 0;
+ __split_page_owner(page, order);
}
static inline void copy_page_owner(struct page *oldpage, struct page *newpage)
{
@@ -58,9 +56,9 @@ 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)
+static inline void split_page_owner(struct page *page,
+ unsigned int order)
{
- return 0;
}
static inline void copy_page_owner(struct page *oldpage, struct page *newpage)
{
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1b1ca57..616ada9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2459,7 +2459,6 @@ 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);
@@ -2473,12 +2472,9 @@ void split_page(struct page *page, unsigned int order)
split_page(virt_to_page(page[0].shadow), order);
#endif

- gfp_mask = get_page_owner_gfp(page);
- set_page_owner(page, 0, gfp_mask);
- for (i = 1; i < (1 << order); i++) {
+ for (i = 1; i < (1 << order); i++)
set_page_refcounted(page + i);
- set_page_owner(page + i, 0, gfp_mask);
- }
+ split_page_owner(page, order);
}
EXPORT_SYMBOL_GPL(split_page);

diff --git a/mm/page_owner.c b/mm/page_owner.c
index 73e202f..499ad26 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -94,17 +94,17 @@ void __set_page_owner_migrate_reason(struct page *page, int reason)
page_ext->last_migrate_reason = reason;
}

-gfp_t __get_page_owner_gfp(struct page *page)
+void __split_page_owner(struct page *page, unsigned int order)
{
+ int i;
struct page_ext *page_ext = lookup_page_ext(page);
+
if (unlikely(!page_ext))
- /*
- * The caller just returns 0 if no valid gfp
- * So return 0 here too.
- */
- return 0;
+ return;

- return page_ext->gfp_mask;
+ page_ext->order = 0;
+ for (i = 1; i < (1 << order); i++)
+ __copy_page_owner(page, page + i);
}

void __copy_page_owner(struct page *oldpage, struct page *newpage)
--
1.9.1