[PATCH] memcg: do not check for mm in mem_cgroup_count_vm_event

[Michal Hocko]

mm given to mem_cgroup_count_vm_event cannot be NULL because the
function is either called from the page fault path or vma->vm_mm is
used. So the check can be dropped.

The check has been introduced by 456f998e (memcg: add the pagefault
count into memcg stats) because the originally proposed patch used
current->mm for shmem but this has been changed to vma->vm_mm later on
without the check being removed (thanks to Hugh for this recollection).

Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
---
 include/linux/memcontrol.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 095d2b4..0108a56 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -188,7 +188,7 @@ void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx);
 static inline void mem_cgroup_count_vm_event(struct mm_struct *mm,
 					     enum vm_event_item idx)
 {
-	if (mem_cgroup_disabled() || !mm)
+	if (mem_cgroup_disabled())
 		return;
 	__mem_cgroup_count_vm_event(mm, idx);
 }
-- 
1.7.10.4

-- 
Michal Hocko
SUSE Labs
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