[PATCH] mm: page_owner: fetch backtrace only for tracked pages

[Sergei Trofimovich]

Very minor optimization.

CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: linux-mm@xxxxxxxxx
Signed-off-by: Sergei Trofimovich <slyfox@xxxxxxxxxx>
---
 mm/page_owner.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/page_owner.c b/mm/page_owner.c
index 63e4ecaba97b..7147fd34a948 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -140,14 +140,14 @@ void __reset_page_owner(struct page *page, unsigned int order)
 {
 	int i;
 	struct page_ext *page_ext;
-	depot_stack_handle_t handle = 0;
+	depot_stack_handle_t handle;
 	struct page_owner *page_owner;
 
-	handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
-
 	page_ext = lookup_page_ext(page);
 	if (unlikely(!page_ext))
 		return;
+
+	handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
 	for (i = 0; i < (1 << order); i++) {
 		__clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
 		page_owner = get_page_owner(page_ext);
-- 
2.31.1