mm/page_owner: introduce split_page_owner and replace manual handling

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.

Link: http://lkml.kernel.org/r/1464230275-25791-4-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 9 insertions, 13 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f07552fc43e1..a82b303c19b1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2461,7 +2461,6 @@ 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);
@@ -2475,12 +2474,9 @@ 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 437877f5b774..31b69437a3d6 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)