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authorJohannes Weiner <hannes@cmpxchg.org>2014-12-10 15:44:30 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 17:41:08 -0800
commit413918bb61b4fa027baa3e79546c47f15e4b9ea8 (patch)
tree439c803ef6cdb6fde9a8dbef510506f519a50338
parentc01f46c7c725f0a1330673bc3c767b89a3b2dbc0 (diff)
downloadop-kernel-dev-413918bb61b4fa027baa3e79546c47f15e4b9ea8.zip
op-kernel-dev-413918bb61b4fa027baa3e79546c47f15e4b9ea8.tar.gz
mm: memcontrol: pull the NULL check from __mem_cgroup_same_or_subtree()
The NULL in mm_match_cgroup() comes from a possibly exiting mm->owner. It makes a lot more sense to check where it's looked up, rather than check for it in __mem_cgroup_same_or_subtree() where it's unexpected. No other callsite passes NULL to __mem_cgroup_same_or_subtree(). Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Vladimir Davydov <vdavydov@parallels.com> 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>
-rw-r--r--include/linux/memcontrol.h5
-rw-r--r--mm/memcontrol.c2
2 files changed, 4 insertions, 3 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index ea00761..e32ab94 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -83,11 +83,12 @@ static inline
bool mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *memcg)
{
struct mem_cgroup *task_memcg;
- bool match;
+ bool match = false;
rcu_read_lock();
task_memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
- match = __mem_cgroup_same_or_subtree(memcg, task_memcg);
+ if (task_memcg)
+ match = __mem_cgroup_same_or_subtree(memcg, task_memcg);
rcu_read_unlock();
return match;
}
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 367cc57..e5dcebd 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1337,7 +1337,7 @@ bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
{
if (root_memcg == memcg)
return true;
- if (!root_memcg->use_hierarchy || !memcg)
+ if (!root_memcg->use_hierarchy)
return false;
return cgroup_is_descendant(memcg->css.cgroup, root_memcg->css.cgroup);
}
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