On Wed, Aug 30, 2017 at 06:03:19PM -0700, Tejun Heo wrote:
> Oops, more like the following.
>
> diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
> index df2e0f1..6f34025 100644
> --- a/kernel/cgroup/cgroup.c
> +++ b/kernel/cgroup/cgroup.c
> @@ -683,7 +683,7 @@ static void css_set_move_task(struct task_struct *task,
> if (it->task_pos == &task->cg_list)
> css_task_iter_advance(it);
>
> - list_del_init(&task->cg_list);
> + list_del(&task->cg_list);
> if (!css_set_populated(from_cset))
> css_set_update_populated(from_cset, false);
> } else {
> @@ -702,6 +702,8 @@ static void css_set_move_task(struct task_struct *task,
> rcu_assign_pointer(task->cgroups, to_cset);
> list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks
> :
> &to_cset->tasks);
> + } else {
> + INIT_LIST_HEAD(&task->cg_list);
> }
> }
On the third thought, I don't think this can happen either because now
migration is strongly synchronized against exits. Please take a look
at the changes around cgroup_threadgroup_rwsem.
Thanks.
--
tejun
