Read copy update the RCU

On Linux, listing of processes will most likely show a process rcu_sched with tty having value of ? Here is an example of a command

ps -ef | grep rcu

UID PID PPID C STIME TTY TIME CMD

root 3 2 0 Jul06 ? 00:00:00 [rcu_gp]
root 4 2 0 Jul06 ? 00:00:00 [rcu_par_gp]
root 10 2 0 Jul06 ? 00:00:00 [rcu_tasks_rude_]
root 11 2 0 Jul06 ? 00:00:00 [rcu_tasks_trace]
root 13 2 0 Jul06 ? 00:03:37 [rcu_sched]

This is a solution on Linux where shared data structures is accessed by many resources. When this data structure encounter an update, those resources at different stages of access need to ensure it is "lock" safe when pointing to specific reference of that data structure.

Anyone encountering errors that mention rcu_sched can refer to kernel.org