Re: [RFC][-mm] Add an owner to the mm_struct (v3)

From: Balbir Singh
Date: Tue Apr 01 2008 - 03:41:01 EST


Paul Menage wrote:
> On Mon, Mar 31, 2008 at 11:23 PM, Balbir Singh
> <balbir@xxxxxxxxxxxxxxxxxx> 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.


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