Subject: Re: [PATCH v6] hugetlb: Add hugetlb.*.numa_stat file
To:     Muchun Song <songmuchun@bytedance.com>,
        Mina Almasry <almasrymina@google.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Shuah Khan <shuah@kernel.org>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Oscar Salvador <osalvador@suse.de>,
        Michal Hocko <mhocko@suse.com>,
        David Rientjes <rientjes@google.com>,
        Shakeel Butt <shakeelb@google.com>, Jue Wang <juew@google.com>,
        Yang Yao <ygyao@google.com>, Joanna Li <joannali@google.com>,
        Cannon Matthews <cannonmatthews@google.com>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
References: <20211111015037.4092956-1-almasrymina@google.com>
 <CAMZfGtWj5LU0ygDpH9B58R48kM8w3tnowQDD53VNMifSs5uvig@mail.gmail.com>
From:   Mike Kravetz <mike.kravetz@oracle.com>
Message-ID: <cfa5a07d-1a2a-abee-ef8c-63c5480af23d@oracle.com>
Date:   Fri, 12 Nov 2021 15:36:12 -0800
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Subject:   Re: [PATCH v6] hugetlb: Add hugetlb.*.numa_stat file

To:        Muchun Song <songmuchun@bytedance.com>, Mina Almasry <almasrymina@google.com>

Cc:        Andrew Morton <akpm@linux-foundation.org>, Shuah Khan <shuah@kernel.org>, Miaohe Lin <linmiaohe@huawei.com>, Oscar Salvador <osalvador@suse.de>, Michal Hocko <mhocko@suse.com>, David Rientjes <rientjes@google.com>, Shakeel Butt <shakeelb@google.com>, Jue Wang <juew@google.com>, Yang Yao <ygyao@google.com>, Joanna Li <joannali@google.com>, Cannon Matthews <cannonmatthews@google.com>, Linux Memory Management List <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>

Bcc:       

-=-=-=-=-=-=-=-=-=# Don't remove this line #=-=-=-=-=-=-=-=-=-

On 11/10/21 6:36 PM, Muchun Song wrote:

> On Thu, Nov 11, 2021 at 9:50 AM Mina Almasry <almasrymina@google.com> wrote:

>>

>> +struct hugetlb_cgroup_per_node {

>> +       /* hugetlb usage in pages over all hstates. */

>> +       atomic_long_t usage[HUGE_MAX_HSTATE];

> 

> Why do you use atomic? IIUC, 'usage' is always

> increased/decreased under hugetlb_lock except

> hugetlb_cgroup_read_numa_stat() which is always

> reading it. So I think WRITE_ONCE/READ_ONCE

> is enough.


Thanks for continuing to work this, I was traveling and unable to

comment.


Unless I am missing something, I do not see a reason for WRITE_ONCE/READ_ONCE

and would suggest going back to the way this code was in v5.

-- 

Mike Kravetz