If you want blazing fast and very scalable performance, you have to do that. Multiple independent contexts in the kernels can have a reference on certain object

If you want blazing fast and very scalable performance, you have to do that. Multiple independent contexts in the kernels can have a reference on certain objects and manipulate them concurrently with relaxed consistency. It would be very impractical to hard-protect certain parts of those objects and guarantee serial consistency. For scalability and performance reasons, certain data structures, objects or certain parts of certain objects could be accessed in a inherently racy manner, but guaranteeing correctness in the existence of races is extremely hard. Any attempt for modularisation, message passing or serial consistency would make your kernel look like a joke compared to Linux. It would make the interaction between subsystems easy but would not provide the opportunity for very fast low latency execution.