kern/50466: vmstat -e hangs

[martin%NetBSD.org@localhost]

>Number:         50466
>Category:       kern
>Synopsis:       vmstat -e hangs
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Nov 23 20:35:00 +0000 2015
>Originator:     Martin Husemann
>Release:        NetBSD 7.99.21
>Organization:
The NetBSD Foundation, Inc.
>Environment:
	
	
System: NetBSD night-owl.duskware.de 7.99.21 NetBSD 7.99.21 (NIGHT-OWL) #362: Sat Nov 21 22:35:47 CET 2015 martin%night-owl.duskware.de@localhost:/usr/src/sys/arch/amd64/compile/NIGHT-OWL amd64
Architecture: x86_64
Machine: amd64
>Description:

vmstat -e hangs for me busy idling one core:

  PID USERNAME PRI NICE   SIZE   RES STATE      TIME   WCPU    CPU COMMAND
  951 martin   117    0    11M 1244K CPU/2      6:29 99.02% 99.02% vmstat

Gdb does not attach to the process.
ktrace does not show any system calls being made.

>How-To-Repeat:
n/a

>Fix:
n/a