[Devel] Re: [PATCH v2 10/11] memcg: allow a memcg with kmem charges to be destructed.

[Glauber Costa]

On 08/21/2012 12:22 PM, Michal Hocko wrote:
> On Thu 09-08-12 17:01:18, Glauber Costa wrote:
>> Because the ultimate goal of the kmem tracking in memcg is to track slab
>> pages as well, we can't guarantee that we'll always be able to point a
>> page to a particular process, and migrate the charges along with it -
>> since in the common case, a page will contain data belonging to multiple
>> processes.
>>
>> Because of that, when we destroy a memcg, we only make sure the
>> destruction will succeed by discounting the kmem charges from the user
>> charges when we try to empty the cgroup.
> 
> This changes the semantic of memory.force_empty file because the usage
> should be 0 on success but it will show kmem usage in fact now. I guess
> it is inevitable with u+k accounting so you should be explicit about
> that and also update the documentation.
aaand, it's done.