Before discussing schedulers, memory, filesystems, or containers, we need to understand how Linux actually executes code. At the core of Linux lies a strict execution model built around two separate worlds:User SpaceKernel SpaceThis separation is not an implementation detail. It is one of the most important design decisions in modern operating systems. Understanding this boundary explains why Linux behaves the way it does — especially when things go wrong.Two Worlds, Two Levels of TrustUser S...