No, it's not a mistake. Each process has it's own virtual address space, but part of that space is typically used to map operating system code and data. The res

No, it's not a mistake. Each process has it's own virtual address space, but part of that space is typically used to map operating system code and data. The reserved part is anywhere from a quarter to a half on a 4GB 32-bit system (I have no idea on a 64bit). Those pages are marked kernel-only. The upper half to three-quarters will be different for each process. One reason for this is so that you can easily trap to the kernel (for an interrupt, a system call, an exception, etc.) without changing the page tables at all -- you just change the cpu mode bit.