Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <13c73151-4b28-4324-afd5-8b84b82bc25d@shopee.com>
Date:   Fri, 16 Dec 2022 15:28:53 +0800
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0)
 Gecko/20100101 Thunderbird/102.6.0
Subject: Re: [PATCH] mm/memcontrol: Skip root memcg in memcg_memory_event_mm
To:     Shakeel Butt <shakeelb@google.com>
Cc:     akpm@linux-foundation.org, roman.gushchin@linux.dev,
        songmuchun@bytedance.com, hannes@cmpxchg.org, vbabka@suse.cz,
        willy@infradead.org, vasily.averin@linux.dev,
        linux-kernel@vger.kernel.org
References: <20221215091907.763801-1-haifeng.xu@shopee.com>
 <20221215181803.ome46pkh6g7qu3t4@google.com>
 <abec13da-c74a-0fd8-74e0-3cdc547e4e08@shopee.com>
 <20221216064210.krxtxebuwc7dijzu@google.com>
From:   Haifeng Xu <haifeng.xu@shopee.com>
In-Reply-To: <20221216064210.krxtxebuwc7dijzu@google.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk


On 2022/12/16 14:42, Shakeel Butt wrote:
> On Fri, Dec 16, 2022 at 09:43:02AM +0800, Haifeng Xu wrote:
>>
>>
>> On 2022/12/16 02:18, Shakeel Butt wrote:
>>> On Thu, Dec 15, 2022 at 09:19:07AM +0000, Haifeng Xu wrote:
>>>> The memory events aren't supported on root cgroup, so there is no need
>>>> to account MEMCG_OOM_KILL on root memcg.
>>>>
>>>
>>> Can you explain the scenario where this is happening and causing issue
>>> for you?
>>>
>> If the victim selected by oom killer belongs to root memcg, memcg_memory_event_mm
>> still counts the MEMCG_OOM_KILL event. This behavior is meaningless because the
>> flag of events/events.local in memory_files is CFTYPE_NOT_ON_ROOT. The root memcg
>> does not count any memory event.
>>
> 
> What about v1's memory.oom_control?
>
 
The memory.oom_control doesn't set the CFTYPE_NOT_ON_ROOT flag. But oom_kill_disable or
under_oom actually only support non-root memcg, so the memory_events should be consistent
with them.