mm: memcontrol: change ug->dummy_page only if memcg changed

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.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions