Hello, It might be better to put this patch at the end rather than in the middle so that when this patch is applied things are actually fixed. > +struct bdi_rcu_device { > + struct device dev; > + struct rcu_head rcu_head; > +}; (cc'ing Greg) Greg, block layer switches association between backing_device_info and its struct device and needs to protect it with RCU. Yufen did so by introducing a wrapping struct around struct device like above. Do you think it'd make sense to just embed rcu_head into struct device and let put_device() to RCU release by default? Thanks. -- tejun