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From: Yang Shi <yang.shi@linux.alibaba.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] mm: vmpressure: use mem_cgroup_is_root API
Date: Wed, 12 Feb 2020 19:18:59 -0800	[thread overview]
Message-ID: <94323469-c9d5-33ab-318b-2677dd966a92@linux.alibaba.com> (raw)
In-Reply-To: <20200212082346.GB11353@dhcp22.suse.cz>



On 2/12/20 12:23 AM, Michal Hocko wrote:
> On Tue 11-02-20 13:24:09, Yang Shi wrote:
>> Use mem_cgroup_is_root() API to check if memcg is root memcg instead of
>> open coding.
> Yes, the direct use outside of memcontrol.c should be really an
> exception. The only other similar case is cgwb_bdi_init and there is no
> easy way to replace - except for adding a helper which is not worth it.

Yes, it seems so. cgwb_bdi_init just deferences root_mem_cgroup to 
access its css. It is the only user outside memcontrol.c, so I agree a 
helper for it might be overkilling. Once we have more users, it should 
be considered.

>
>> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
> Acked-by: Michal Hocko <mhocko@suse.com>

Thanks.

>
> Thanks!
>
>> ---
>>   mm/vmpressure.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/vmpressure.c b/mm/vmpressure.c
>> index 0590f00..d69019f 100644
>> --- a/mm/vmpressure.c
>> +++ b/mm/vmpressure.c
>> @@ -280,7 +280,7 @@ void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
>>   		enum vmpressure_levels level;
>>   
>>   		/* For now, no users for root-level efficiency */
>> -		if (!memcg || memcg == root_mem_cgroup)
>> +		if (!memcg || mem_cgroup_is_root(memcg))
>>   			return;
>>   
>>   		spin_lock(&vmpr->sr_lock);
>> -- 
>> 1.8.3.1
>>


  reply	other threads:[~2020-02-13  3:19 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-11  5:24 [PATCH 1/2] mm: vmpressure: don't need call kfree if kstrndup fails Yang Shi
2020-02-11  5:24 ` [PATCH 2/2] mm: vmpressure: use mem_cgroup_is_root API Yang Shi
2020-02-12  2:08   ` David Rientjes
2020-02-12  8:23   ` Michal Hocko
2020-02-13  3:18     ` Yang Shi [this message]
2020-02-12 11:19   ` David Hildenbrand
2020-02-12  2:07 ` [PATCH 1/2] mm: vmpressure: don't need call kfree if kstrndup fails David Rientjes
2020-02-12 11:21 ` David Hildenbrand
2020-02-13  3:14   ` Yang Shi
2020-02-13  4:48     ` Andrew Morton
2020-02-13  4:51       ` Yang Shi

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