The MIT Operating Systems opencourseware class labs has some great exercises when learning about operating systems[0]. I've also found older linux kernels, like

The MIT Operating Systems opencourseware class labs has some great exercises when learning about operating systems[0]. I've also found older linux kernels, like v1.0, are easier to follow for learning [1]. [0]https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-828-operating-system-engineering-fall-2012/labs/ https://ocw.mit.edu/courses/electrical-engineering-and-compu... [1]https://mirrors.edge.kernel.org/pub/linux/kernel/v1.0/ https://mirrors.edge.kernel.org/pub/linux/kernel/v1.0/