[PATCH v4 3/5] mm: memcontrol: change ug->dummy_page only if memcg changed

[Muchun Song]

Just like assignment to ug->memcg, we only need to update ug->dummy_page
if memcg changed. So move it to there. This is a very small optimization.

Signed-off-by: Muchun Song <songmuc...@bytedance.com>
---
 mm/memcontrol.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index fc22da9805fb..104bddf21314 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6845,6 +6845,7 @@ static void uncharge_page(struct page *page, struct 
uncharge_gather *ug)
                        uncharge_gather_clear(ug);
                }
                ug->memcg = page_memcg(page);
+               ug->dummy_page = page;
 
                /* pairs with css_put in uncharge_batch */
                css_get(&ug->memcg->css);
@@ -6858,7 +6859,6 @@ static void uncharge_page(struct page *page, struct 
uncharge_gather *ug)
        else
                ug->pgpgout++;
 
-       ug->dummy_page = page;
        page->memcg_data = 0;
        css_put(&ug->memcg->css);
 }
-- 
2.11.0