PF_SUSPEND_TASK
if (p->flags & (PF_NOFREEZE | PF_SUSPEND_TASK))
current->flags |= PF_SUSPEND_TASK;
WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
curr->flags &= ~PF_SUSPEND_TASK;