Messages in this thread | | | Date | Thu, 16 Mar 2017 12:07:34 -0400 | From | Tejun Heo <> | Subject | Re: [PATCH 2/2] kthread, cgroup: close race window where new kthreads can be migrated to non-root cgroups |
| |
Hello,
On Thu, Mar 16, 2017 at 04:39:26PM +0100, Oleg Nesterov wrote: > Either way, I am wondering if we can do something really trivial like > the patch below. This way we can also remove the "tsk == kthreadd_task" > check, and we do not need the barriers. > > Oleg. > > --- x/kernel/kthread.c > +++ x/kernel/kthread.c > @@ -226,6 +226,7 @@ > ret = -EINTR; > if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { > __kthread_parkme(self); > + current->flags &= ~PF_IDONTLIKECGROUPS; > ret = threadfn(data); > } > do_exit(ret); > @@ -537,7 +538,7 @@ > set_cpus_allowed_ptr(tsk, cpu_all_mask); > set_mems_allowed(node_states[N_MEMORY]); > > - current->flags |= PF_NOFREEZE; > + current->flags |= (PF_NOFREEZE | PF_IDONTLIKECGROUPS); > > for (;;) { > set_current_state(TASK_INTERRUPTIBLE); > --- x/kernel/cgroup/cgroup.c > +++ x/kernel/cgroup/cgroup.c > @@ -2429,7 +2429,7 @@ > * trapped in a cpuset, or RT worker may be born in a cgroup > * with no rt_runtime allocated. Just say no. > */ > - if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { > + if (tsk->flags & (PF_NO_SETAFFINITY | PF_IDONTLIKECGROUPS)) { > ret = -EINVAL; > goto out_unlock_rcu; > }
Absolutely. If we're willing to spend a PF flag on it, we can properly wait for it too instead of failing it.
Thanks.
-- tejun
| |