Answer

Forum: The Linux Kernel Hackers' Guide
Re: multitasking (Dennis J Perkins)
Keywords: multitasking
Date: Mon, 20 Apr 1998 15:32:10 GMT
From: David Welch <welch@mcmail.com>

Both. User level processes can preempted in user mode but code running in kernel mode (either by using a system call or by a dedicated kernel thread) is only preempted when it chooses to give up control