Re: [PATCHv9 1/3] rdmacg: Added rdma cgroup controller

[Parav Pandit]

On Thu, Mar 3, 2016 at 1:44 PM, Haggai Eran <haggaie@xxxxxxxxxxxx> wrote:
> On 03/03/2016 05:18, Parav Pandit wrote:
>> On Thu, Mar 3, 2016 at 1:28 AM, Parav Pandit <pandit.parav@xxxxxxxxx> wrote:
>>> On Wed, Mar 2, 2016 at 11:09 PM, Tejun Heo <tj@xxxxxxxxxx> wrote:
>>>> Nothing seems to prevent @cg from going away if this races with
>>>> @current being migrated to a different cgroup.  Have you run this with
>>>> lockdep and rcu debugging enabled?  This should have triggered a
>>>> warning.
>> I am able to reproduce this race. Looking into how to address it.
>
> If I understand correctly, task_css() requires rcu read lock being held.
> Is task_get_css() suitable here?

Yes. Its suitable if we continue with newer API to drop "num" entries.
Or I will have make minor modification to support that in cgroup.h.
There is no variation as task_get_css_many, but its minor change anyway.
I saw slept off yesterday night, saw today morning.
Will test over weekend and wait for Tejun's opinion if there is any.