linux-kernel - Re: [PATCH v3 02/21] memcg: make mm_match

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Message-ID: <4F4C74D7.90704@openvz.org>
Date:	Tue, 28 Feb 2012 10:31:51 +0400
From:	Konstantin Khlebnikov <khlebnikov@...nvz.org>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
CC:	Hugh Dickins <hughd@...gle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH v3 02/21] memcg: make mm_match_cgroup() hirarchical

KAMEZAWA Hiroyuki wrote:
> On Thu, 23 Feb 2012 17:51:46 +0400
> Konstantin Khlebnikov<khlebnikov@...nvz.org>  wrote:
>
>> Check mm-owner cgroup membership hierarchically.
>>
>> Signed-off-by: Konstantin Khlebnikov<khlebnikov@...nvz.org>
>
>
> Ack. but ... see below.
>
>> ---
>>   include/linux/memcontrol.h |   11 ++---------
>>   mm/memcontrol.c            |   20 ++++++++++++++++++++
>>   2 files changed, 22 insertions(+), 9 deletions(-)
>>
>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>> index 8c4d74f..4822d53 100644
>> --- a/include/linux/memcontrol.h
>> +++ b/include/linux/memcontrol.h
>> @@ -87,15 +87,8 @@ extern struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm);
>>   extern struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg);
>>   extern struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont);
>>
>> -static inline
>> -int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *cgroup)
>> -{
>> -	struct mem_cgroup *memcg;
>> -	rcu_read_lock();
>> -	memcg = mem_cgroup_from_task(rcu_dereference((mm)->owner));
>> -	rcu_read_unlock();
>> -	return cgroup == memcg;
>> -}
>> +extern int mm_match_cgroup(const struct mm_struct *mm,
>> +			   const struct mem_cgroup *cgroup);
>>
>>   extern struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg);
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index b8039d2..77f5d48 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -821,6 +821,26 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
>>   				struct mem_cgroup, css);
>>   }
>>
>> +/**
>> + * mm_match_cgroup - cgroup hierarchy mm membership test
>> + * @mm		mm_struct to test
>> + * @cgroup	target cgroup
>> + *
>> + * Returns true if mm belong this cgroup or any its child in hierarchy
>
> belongs to ?
>
>> + */
>> +int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *cgroup)
>> +{
>
> Please use "memcg" for representing "memory cgroup" (other function's arguments uses "memcg")
>
>> +	struct mem_cgroup *memcg;
>
> So, rename this as *cur_memcg or some.
>
>> +
>> +	rcu_read_lock();
>> +	memcg = mem_cgroup_from_task(rcu_dereference((mm)->owner));
>> +	while (memcg != cgroup&&  memcg&&  memcg->use_hierarchy)
>> +		memcg = parent_mem_cgroup(memcg);
>
> IIUC, parent_mem_cgroup() checks mem->res.parent. mem->res.parent is set only when
> parent->use_hierarchy == true. Then,
>
> 	while (memcg != cgroup)
> 		memcg = parent_mem_cgroup(memcg);
>
> will be enough.

Here will be mem_cgroup_same_or_subtree(), see reply from Johannes Weiner.

>
> Thanks,
> -Kame
>

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