rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-...D } 2631 jiffies s: 3013 root: 0x2/. rcu: blocking rcu_node structures (internal RCU debug): Task dump for CPU 1: task:swapper/1 state:R running task stack:28304 pid: 0 ppid: 1 flags:0x00004008 Call Trace: