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Subject: Re: [PATCH v9 02/20] mm/memcg: fold lock_page_lru into commit_charge
To:     Hillf Danton <hdanton@sina.com>
Cc:     cgroups@vger.kernel.org, akpm@linux-foundation.org,
        mgorman@techsingularity.net, tj@kernel.org, hughd@google.com,
        khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com,
        yang.shi@linux.alibaba.com, willy@infradead.org,
        hannes@cmpxchg.org, lkp@intel.com,
        Michal Hocko <mhocko@kernel.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <1583146830-169516-1-git-send-email-alex.shi@linux.alibaba.com>
 <20200304031335.9784-1-hdanton@sina.com>
From:   Alex Shi <alex.shi@linux.alibaba.com>
Message-ID: <4131e7d9-acad-4372-73b1-6fa1b0b251ef@linux.alibaba.com>
Date:   Wed, 4 Mar 2020 15:19:46 +0800
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?? 2020/3/4 ????11:13, Hillf Danton д??:
>>  	 * Nobody should be changing or seriously looking at
>>  	 * page->mem_cgroup at this point:
>> @@ -2633,8 +2611,13 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg,
>>  	 */
>>  	page->mem_cgroup = memcg;
>>  
> Well it is likely to update memcg for page without lru_lock held even if
> more care is required, which is a change added in the current semantic and
> worth a line of words in log.
> 

the lru_lock is guard for lru list, not for page->mem_cgroup, seem no need to highlight this point. Do we?

Thanks
Alex