On Wed, 2018-01-24 at 00:41 +0800, Ming Lei wrote: > Could you explain where to call call_rcu()? call_rcu() can't be used in > IO path at all. Can you explain what makes you think that call_rcu() can't be used in the I/O path? As you know call_rcu() invokes a function asynchronously. From Documentation/RCU/Design/Requirements/Requirements.html: The <tt>call_rcu()</tt> function may be used in a number of situations where neither <tt>synchronize_rcu()</tt> nor <tt>synchronize_rcu_expedited()</tt> would be legal, including within preempt-disable code, <tt>local_bh_disable()</tt> code, interrupt-disable code, and interrupt handlers. Bart.
