> why Linux uses offsetof Essentially, downcasting with "multiple inheritance" (non-linear subtyping) and thin pointers - objects can be members of several int

> why Linux uses offsetof Essentially, downcasting with "multiple inheritance" (non-linear subtyping) and thin pointers - objects can be members of several intrusive linked lists, held by different parts of the kernel, and container_of is used to get an object from the LL pointer after you know the type.