PANIC: sent too much

hello
sometimes i got this panic
with high load on network interfaces

map02# cat info.0
Good dump found on device /dev/ad2s1b
  Architecture: i386
  Architecture version: 1
  Dump length: 268369920B (255 MB)
  Blocksize: 512
  Dumptime: Sat Jan 17 10:21:26 2004
  Hostname: map02.modrany.czf
  Versionstring: FreeBSD 5.2-CURRENT #3: Mon Jan 12 18:17:30 CET 2004
    mik_at_map02.modrany.czf:/usr/obj/usr/src/sys/ROUTER-IPFW
  Panicstring: sent too much
  Bounds: 0


(kgdb) bt
#0  doadump () at /usr/src/sys/kern/kern_shutdown.c:240
#1  0xc0634eec in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:372
#2  0xc0635277 in panic () at /usr/src/sys/kern/kern_shutdown.c:550
#3  0xc065a77b in propagate_priority (td=0xc14df000) at 
/usr/src/sys/kern/subr_turnstile.c:176
#4  0xc065b1ed in turnstile_wait (ts=0xc14d7100, lock=0xc096546c, 
owner=0xc14df000) at /usr/src/sys/kern/subr_turnstile.c:510
#5  0xc062b895 in _mtx_lock_sleep (m=0xc096546c, opts=0, file=0x0, 
line=0) at /usr/src/sys/kern/kern_mutex.c:482
#6  0xc062b3b7 in _mtx_lock_flags (m=0xc096546c, opts=0, file=0xc0887efa 
"/usr/src/sys/netinet/tcp_timer.c", line=488)
    at /usr/src/sys/kern/kern_mutex.c:218
#7  0xc06dffe0 in tcp_timer_rexmt (xtp=0xc302b170) at 
/usr/src/sys/netinet/tcp_timer.c:488
#8  0xc06458c8 in softclock (dummy=0x0) at 
/usr/src/sys/kern/kern_timeout.c:226
#9  0xc06213f2 in ithread_loop (arg=0xc14dc500) at 
/usr/src/sys/kern/kern_intr.c:544
#10 0xc06203e4 in fork_exit (callout=0xc0621260 <ithread_loop>, arg=0x0, 
frame=0x0) at /usr/src/sys/kern/kern_fork.c:797
(kgdb) up 3
#3  0xc065a77b in propagate_priority (td=0xc14df000) at 
/usr/src/sys/kern/subr_turnstile.c:176
176                     KASSERT(!TD_IS_SLEEPING(td),
(kgdb) list
171                      * first thread to grab a slock of a sx lock.  
In that case
172                      * it is possible for us to be at SSLEEP or some 
other
173                      * weird state.  We should probably just return 
if the state
174                      * isn't SRUN or SLOCK.
175                      */
176                     KASSERT(!TD_IS_SLEEPING(td),
177                         ("sleeping thread (pid %d) owns a 
non-sleepable lock",
178                         td->td_proc->p_pid));
179
180                     /*

my interfaces are:
wi0: <Intersil Prism2.5> mem 0xe6000000-0xe6000fff irq 11 at device 9.0 
on pci0
wi0: Intersil Firmware: Primary (1.1.1), Station (1.7.4)
wi1: <Intersil Prism2.5> mem 0xe6001000-0xe6001fff irq 10 at device 10.0 
on pci0
wi1: Intersil Firmware: Primary (1.1.1), Station (1.7.4)
wi2: <Intersil Prism2.5> mem 0xe6002000-0xe6002fff irq 12 at device 11.0 
on pci0
wi2: Intersil Firmware: Primary (1.1.1), Station (1.7.4)
wi3: <Intersil Prism2.5> mem 0xe6003000-0xe6003fff irq 5 at device 12.0 
on pci0
wi3: Intersil Firmware: Primary (1.1.1), Station (1.7.4)
rl0: <RealTek 8139 10/100BaseTX> port 0xd000-0xd0ff mem 
0xe6004000-0xe60040ff irq 10 at device 14.0 on pci0

Jiri