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From:   Waiman Long <llong@redhat.com>
Subject: Re: [PATCH v4 1/5] mm/memcg: Move mod_objcg_state() to memcontrol.c
To:     Johannes Weiner <hannes@cmpxchg.org>
Cc:     Michal Hocko <mhocko@kernel.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Tejun Heo <tj@kernel.org>, Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Vlastimil Babka <vbabka@suse.cz>, Roman Gushchin <guro@fb.com>,
        linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        linux-mm@kvack.org, Shakeel Butt <shakeelb@google.com>,
        Muchun Song <songmuchun@bytedance.com>,
        Alex Shi <alex.shi@linux.alibaba.com>,
        Chris Down <chris@chrisdown.name>,
        Yafang Shao <laoar.shao@gmail.com>,
        Wei Yang <richard.weiyang@gmail.com>,
        Masayoshi Mizuma <msys.mizuma@gmail.com>,
        Xing Zhengjun <zhengjun.xing@linux.intel.com>,
        Matthew Wilcox <willy@infradead.org>
References: <20210419000032.5432-1-longman@redhat.com>
 <20210419000032.5432-2-longman@redhat.com> <YH2eT+JCII48hX80@cmpxchg.org>
 <ffb5705e-8629-808d-9d09-0c9c7f509326@redhat.com>
Message-ID: <140444ea-14e7-b305-910f-f23fafe45488@redhat.com>
Date:   Mon, 19 Apr 2021 12:18:29 -0400
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On 4/19/21 11:21 AM, Waiman Long wrote:
> On 4/19/21 11:14 AM, Johannes Weiner wrote:
>> On Sun, Apr 18, 2021 at 08:00:28PM -0400, Waiman Long wrote:
>>> The mod_objcg_state() function is moved from mm/slab.h to 
>>> mm/memcontrol.c
>>> so that further optimization can be done to it in later patches without
>>> exposing unnecessary details to other mm components.
>>>
>>> Signed-off-by: Waiman Long <longman@redhat.com>
>>> ---
>>>   mm/memcontrol.c | 13 +++++++++++++
>>>   mm/slab.h       | 16 ++--------------
>>>   2 files changed, 15 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>>> index e064ac0d850a..dc9032f28f2e 100644
>>> --- a/mm/memcontrol.c
>>> +++ b/mm/memcontrol.c
>>> @@ -3150,6 +3150,19 @@ void __memcg_kmem_uncharge_page(struct page 
>>> *page, int order)
>>>       css_put(&memcg->css);
>>>   }
>>>   +void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data 
>>> *pgdat,
>>> +             enum node_stat_item idx, int nr)
>>> +{
>>> +    struct mem_cgroup *memcg;
>>> +    struct lruvec *lruvec = NULL;
>>> +
>>> +    rcu_read_lock();
>>> +    memcg = obj_cgroup_memcg(objcg);
>>> +    lruvec = mem_cgroup_lruvec(memcg, pgdat);
>>> +    mod_memcg_lruvec_state(lruvec, idx, nr);
>>> +    rcu_read_unlock();
>>> +}
>> It would be more naturally placed next to the others, e.g. below
>> __mod_lruvec_kmem_state().
>>
>> But no deal breaker if there isn't another revision.
>>
>> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
>>
> Yes, there will be another revision by rebasing patch series on the 
> linux-next. I will move the function then. 

OK, it turns out that mod_objcg_state() is only defined if 
CONFIG_MEMCG_KMEM. That was why I put it in the CONFIG_MEMCG_KMEM block 
with the other obj_stock functions. I think I will keep it there.

Thanks,
Longman