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;
Subject: Re: [PATCH] mm/memcg: remove definition of MEM_CGROUP_ID_MAX when
 !CONFIG_MEMCG
To:     Muchun Song <muchun.song@linux.dev>
CC:     Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        Shakeel Butt <shakeelb@google.com>, <cgroups@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux Memory Management List <linux-mm@kvack.org>
References: <20230706112820.2393447-1-linmiaohe@huawei.com>
 <892B507C-CFE8-4792-BA5F-3C698290A8EE@linux.dev>
 <61ce2910-f3de-cfb7-bdd3-546ade0cb6f3@huawei.com>
 <52C942A9-29F7-473F-8674-6CB584F009BA@linux.dev>
From:   Miaohe Lin <linmiaohe@huawei.com>
Message-ID: <f94905da-b98e-0a18-a9d8-18ee109be566@huawei.com>
Date:   Fri, 7 Jul 2023 10:38:27 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101
 Thunderbird/78.6.0
MIME-Version: 1.0
In-Reply-To: <52C942A9-29F7-473F-8674-6CB584F009BA@linux.dev>
Content-Type: text/plain; charset="utf-8"
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 2023/7/7 10:25, Muchun Song wrote:
> 
> 
>> On Jul 7, 2023, at 10:06, Miaohe Lin <linmiaohe@huawei.com> wrote:
>>
>> On 2023/7/7 9:47, Muchun Song wrote:
>>>
>>>
>>>> On Jul 6, 2023, at 19:28, Miaohe Lin <linmiaohe@huawei.com> wrote:
>>>>
>>>> MEM_CGROUP_ID_MAX is only used when CONFIG_MEMCG is configured. Remove
>>>> unneeded !CONFIG_MEMCG variant.
>>>>
>>>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>>>
>>> MEM_CGROUP_ID_MAX is also only used in mem_cgroup_alloc(), maybe you also
>>> could move it from memcontrol.h to memcontrol.c. And define it as:
>>>
>>> #define MEM_CGROUP_ID_MAX ((1U << MEM_CGROUP_ID_SHIFT) - 1)
>>>
>>> I am not suggesting defining it as USHRT_MAX, because if someone changes
>>> MEM_CGROUP_ID_SHIFT in the future, then MEM_CGROUP_ID_MAX will not updated
>>> accordingly.
>>
>> Looks sensible to me. Do you suggest squashing above changes into the current patch
>> or a separate patch is preferred?
> 
> I think it's better to squash.

Will do if no objection. Thanks.