[PATCH v2 1/2] mm: memcontrol: use memcg_kmem_enabled in count_objcg_event

Kairui Song
2022-09-19T18:06:33Z

From: Kairui Song <kasong-1Nz4purKYjRBDgjK7y7TUQ@public.gmane.org>

There are currently two helpers for checking if cgroup kmem
accounting is enabled:

- mem_cgroup_kmem_disabled
- memcg_kmem_enabled

mem_cgroup_kmem_disabled is a simple helper that returns true
if cgroup.memory=nokmem is specified, otherwise returns false.

memcg_kmem_enabled is a bit different, it returns true if
cgroup.memory=nokmem is not specified and there was at least one
non-root memory control enabled cgroup ever created. This help improve
performance when kmem accounting was not actually activated. And it's
optimized with static branch.

The usage of mem_cgroup_kmem_disabled is for sub-systems that need to
preallocate data for kmem accounting since they could be initialized
before kmem accounting is activated. But count_objcg_event doesn't
need that, so using memcg_kmem_enabled is better here.

Signed-off-by: Kairui Song <kasong-1Nz4purKYjRBDgjK7y7TUQ@public.gmane.org>
---
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 6257867fbf95..e6d3d5870d6f 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1779,7 +1779,7 @@ static inline void count_objcg_event(struct obj_cgroup *objcg,
{
struct mem_cgroup *memcg;

- if (mem_cgroup_kmem_disabled())
+ if (!memcg_kmem_enabled())
return;

rcu_read_lock();
--
2.35.2