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SubjectRe: [RFC][-mm] Add an owner to the mm_struct (v3)
Balbir Singh wrote:
> Paul Menage wrote:
>> On Mon, Mar 31, 2008 at 11:23 PM, Balbir Singh
>> <balbir@linux.vnet.ibm.com> wrote:
>>> > Here we'll want to call vm_cgroup_update_mm_owner(), to adjust the
>>> > accounting. (Or if in future we end up with more than a couple of
>>> > subsystems that want notification at this time, we'll want to call
>>> > cgroup_update_mm_owner() and have it call any interested subsystems.
>>> >
>>>
>>> I don't think we need to adjust accounting, since only mm->owner is changing and
>>> not the cgroup to which the task/mm belongs. Do we really need to notify? I
>>> don't want to do any notifications under task_lock().
>> It's possible but unlikely that the new owner is in a different cgroup.
>
> Hmmm... that can never happen with thread groups, since mm->owner is
> p->group_leader and that never exits unless all threads are gone (it can
> explicitly change groups though). Without thread groups, the new owner can
> belong to a different cgroup, so we might need notification.
>
>

Thinking out aloud

If mm->owner changes and belongs to a different cgroup, we have a whole new
problem. We need to determine all tasks that share the mm and belong to a
particular cgroup, which changed since the new owner belongs to a different
cgroup and then update the charge.


--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL


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