In the output of /proc/PID/maps, each line of the output is actually extrapolated from a kernel metadata structure called a VMA. It's quite straightforward, really: the kernel uses the VMA data structure to abstract what we have been calling a segment or mapping. Thus, for every single segment in the user VAS, there is a VMA object maintained by the OS. Please realize that only user space segments or mappings are governed by the kernel metadata structure called the VMA; the kernel segment itself has no VMAs.
So, how many VMAs will a given process have? Well, it's equal to the number of mappings (segments) in its user VAS. In our example with the FAHViewer process, it happened to have 206 segments or mappings, implying that there are 206 VMA metadata objects – representing the 206 user space segments or mappings – for this process in kernel memory.
Programmatically speaking, the kernel maintains...
