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memcg: do not check for mm in __mem_cgroup_count_vm_event

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The 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 was introduced by commit 456f998ec817 ("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@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michal Hocko 2012-12-12 13:52:23 -08:00 committed by Linus Torvalds
parent 220f2ac913
commit c95d26c2ff
1 changed files with 0 additions and 3 deletions
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3
mm/memcontrol.c
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@ -1021,9 +1021,6 @@ void __mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
{
struct mem_cgroup *memcg;
if (!mm)
return;
rcu_read_lock();
memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
if (unlikely(!memcg))