The Kernel's process table is proc:

EXTERN struct proc proc[NR_TASKS + NR_PROCS];/* process table */

Compare this with pm's process table mproc:

struct mproc mproc[NR_PROCS];

NR_TASKS and NR_PROCS are defined:

#define NR_PROCS 100
#define NR_TASKS 4

/* Kernel tasks. These all run in the same address space. */
#define IDLE             -4/* runs when no one else can run */
#define CLOCK   -3/* alarms and other clock functions */
#define SYSTEM           -2/* request system functionality */
#define KERNEL           -1/* pseudo-process for IPC and scheduling */

/* Number of tasks. Note that NR_PROCS is defined in
<minix/config.h>. */
#define NR_TASKS  4 

This just means that the kernel manages 4 more processes than the process manager. That is, the process manager only manages the processes that run in user mode. The kernel manages all processes including the tasks which run in kernel mode.