memcg: remove unnecessary !mm check from try_get_mem_cgroup_from_mm()

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@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner 2014-04-07 15:37:42 -07:00 committed by Linus Torvalds
parent 284f39afea
commit 03583f1a63

View file

@ -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));