Chapter 4. Process Address Space

One of the principal advantages of virtual memory is that each process has its own virtual address space, which is mapped to physical memory by the operating system. In this chapter I discuss the process address space and how Linux manages it.

The kernel treats the userspace portion of the address space very differently from the kernel portion. For example, allocations for the kernel are satisfied immediately and are visible globally no matter what process is on the CPU. vmalloc() is an exception because a minor page fault will occur to sync the process page tables with the reference page tables, but the page will still be allocated immediately upon request. With a process, space is simply reserved in the linear ...

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