Commit c95d26c2 authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds
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memcg: do not check for mm in __mem_cgroup_count_vm_event 



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 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: default avatarMichal 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 220f2ac9

mm/memcontrol.c

+0 −3
Original line number Diff line number Diff line
@@ -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))