Is the kernel loaded into memory for every user simultaneously using a Multi-User O.S. system?
The shell (or window manager) which provides a visual interface is not part of the kernel. It's a simple user process and it runs in userspace without elevated privileges. In order for the user to &quot;log in&quot;, which involves associating their terminal with the shell (or window manager), a login manager is needed. This program does run with elevated privileges, but it is also not part of the kernel. And there is only one instance of it.
Almost all user processes interact at some point with the kernel, usually by triggering a software interrupt which is caught by the kernel and triggers some kind of kernel request handler. There is only one copy of the executable image which contains kernel functions, but each handler needs to run independently and normally requires some transient storage. This would most naturally be stored on a stack, as with the transient storage for any ordinary procedure. However the &quot;kernel stack&quot; for a process is provided, it will by unique to the process. But it's usually not very big at all.