kern/134157: dummynet loads cpu for 100% and make a system frozen and unstable

Sat May 2 11:00:05 UTC 2009

>Number:         134157
>Category:       kern
>Synopsis:       dummynet loads cpu for 100% and make a system frozen and unstable
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat May 02 11:00:04 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     Andrey Golenischev
>Release:        7.1-RELEASE-p5
>Organization:
PP "Neiron Systems"
>Environment:
FreeBSD access 7.1-RELEASE-p5 FreeBSD 7.1-RELEASE-p5 #0: Sun Apr 26 12:25:17 EEST 2009     megasid at access:/usr/src/sys/i386/compile/ACCESS  i386

>Description:
We use ipfw dummynet for shaping our vpn users. When we use 6.x freebsd and 7.0 freebsd there is no bugs with dummynet. When we upgrade to 7.1 our access server start to freez and only hardware reset can back it to life. When i left in ssh session and this nightmare come back i see that dummynet is loads 100% of cpu and i cannot stop any daemons or restart server.

How is looks in top -SI

last pid: 58567;  load averages:  1.57,  3.18, 2.71                                                                                  up 0+13:56:00  13:55:32
96 processes:  4 running, 79 sleeping, 13 waiting
CPU:  0.0% user,  0.0% nice, 50.0% system,  0.8% interrupt, 49.2% idle
Mem: 85M Active, 381M Inact, 179M Wired, 112K Cache, 112M Buf, 1356M Free
Swap: 4061M Total, 4061M Free

  PID USERNAME  THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU COMMAND
   12 root        1 171 ki31     0K     8K RUN    0 698:09 100.00% idle: cpu0
   29 root        1 -68    -     0K     8K CPU1   1  96:34 100.00% dummynet

>How-To-Repeat:
Just use much ipfw pipes with random add/delete it and speed change
>Fix:
No

>Release-Note:
>Audit-Trail:
>Unformatted: