[patch 5/8] memcg: remove unnecessary !mm check from try_get_mem_cgroup_from_mm()

[Johannes Weiner]

Users pass either a mm that has been established under task lock, or
use a verified current->mm, which means the task can't be exiting.

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
---
 mm/memcontrol.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c40186cf22ad..1780e66ec61e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1075,13 +1075,6 @@ struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
 {
 	struct mem_cgroup *memcg = NULL;
 
-	if (!mm)
-		return NULL;
-	/*
-	 * Because we have no locks, mm->owner's may be being moved to other
-	 * cgroup. We use css_tryget() here even if this looks
-	 * pessimistic (rather than adding locks here).
-	 */
 	rcu_read_lock();
 	do {
 		memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
-- 
1.9.0

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