Re: [RFC PATCH] mm: thp: grab the lock before manipulation defer list

From: Wei Yang
Date: Fri Jan 03 2020 - 18:39:33 EST

On Fri, Jan 03, 2020 at 11:29:06AM -0800, David Rientjes wrote:
>On Fri, 3 Jan 2020, Wei Yang wrote:
>> As all the other places, we grab the lock before manipulate the defer list.
>> Current implementation may face a race condition.
>> Fixes: 87eaceb3faa5 ("mm: thp: make deferred split shrinker memcg aware")
>> Signed-off-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
>> ---
>> I notice the difference during code reading and just confused about the
>> difference. No specific test is done since limited knowledge about cgroup.
>> Maybe I miss something important?
>The check for !list_empty(page_deferred_list(page)) must certainly be
>serialized with doing list_del_init(page_deferred_list(page)).

Hi David

Would you mind giving more information? You mean list_empty and list_del_init
is atomic?

Wei Yang
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