port-sun3/48432: System hangs under light load

[jcarr%poethecat.com@localhost]

>Number:         48432
>Category:       port-sun3
>Synopsis:       System hangs under light load
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    port-sun3-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Dec 07 15:40:00 +0000 2013
>Originator:     John Carr
>Release:        NetBSD/sun3-6.1.2
>Organization:
>Environment:
NetBSD moonbeam 6.1.2 NetBSD 6.1.2 (GENERIC) sun3                               

>Description:
(noticed same issue on an upgrade from NetBSD-5.2.1 to 6.1.2 as well as a new 
install of 6.1.2. Additionally, seen on 6.0, 6.1, 6.1.1)

System will, essentially, just hang, unable to create new processes with no 
syslog output. Existing processes will continue, but any new ones created (like 
cron instances, shells in screen, etc.) will not finish; they'll spawn, but 
hang. Additionally, they cannot be killed. Within a pretty short amount of 
time, the system grinds itself down as processes get backed up and nothing will 
run. I've recreated this happen on a system running nothing more than screen 
with top in one window. Additionally, it's happened in single user when running 
a few commands in a row. I've not seen a commonality of how/when this happens 
yet. The only recourse is to break to debugger and sync, halt, or reboot.

That said, it can be easily recreated but not in a consistent manner. However, 
I've yet to have the system run for more than about 10 minutes of consistent 
use (edit of files, man, ftp, etc.) before it hangs. Essentially, it's not a 
usable system for much more than login and top.

My guess would be that this is a kernel issue, but I'm not sure what info to 
provide. More than happy to do so.
>How-To-Repeat:
Use the system.
>Fix:
N/A