Messages in this thread | | | Date | Wed, 30 Aug 2017 18:12:30 -0700 | From | Tejun Heo <> | Subject | Re: [PATCH] cgroup: Fix potential race between cgroup_exit and migrate path |
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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
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