kernel fault -- 2.6.15 with tux patch applied

I had this problem on another machine, but, thought it was a one-off
issue.  I issued the command reboot which caused this fault.

After tux has served data, it appears to get this error.  Configuration 
of both machines with the issue are SMP machines (not SMT or 
Uniprocessor).  I'll try again on a uniprocessor machine to see if the 
problem persists.

Any pointers for diagnosing?

Jan 19 22:06:45 machine3 kernel: TUX: thread 1 stopping ...
Jan 19 22:06:45 machine3 kernel: TUX: thread 0 stopping ...
Jan 19 22:06:45 machine3 kernel: Unable to handle kernel NULL pointer
dereference at virtual address 00000020
Jan 19 22:06:45 machine3 kernel:  printing eip:
Jan 19 22:06:45 machine3 kernel: c02d5541
Jan 19 22:06:45 machine3 kernel: *pde = 00000000
Jan 19 22:06:45 machine3 kernel: Oops: 0002 [#1]
Jan 19 22:06:45 machine3 kernel: SMP
Jan 19 22:06:45 machine3 kernel: Modules linked in:
Jan 19 22:06:45 machine3 kernel: CPU:    0
Jan 19 22:06:45 machine3 kernel: EIP:
0060:[tux_flush_workqueue+81/185]    Not tainted VLI
Jan 19 22:06:45 machine3 kernel: EFLAGS: 00010206   (2.6.15-tux3)
Jan 19 22:06:45 machine3 kernel: EIP is at tux_flush_workqueue+0x51/0xb9
Jan 19 22:06:45 machine3 kernel: eax: 00000000   ebx: f7bc0000   ecx:
f7bc0028   edx: f7bc8028
Jan 19 22:06:45 machine3 kernel: esi: c03ded20   edi: 00000000   ebp:
00000140   esp: f7343f10
Jan 19 22:06:45 machine3 kernel: ds: 007b   es: 007b   ss: 0068
Jan 19 22:06:45 machine3 kernel: Process tux (pid: 2234,
threadinfo=f7342000 task=f72fea30)
Jan 19 22:06:45 machine3 kernel: Stack: 00000003 c03ded20 c03ded20
c02df38c c03ded20 c03ded20 c03ded20 c03dede0
Jan 19 22:06:45 machine3 kernel:        c03dee70 c02df467 c03ded20
c03ded20 f7342000 00000004 c03ded20 00000000
Jan 19 22:06:45 machine3 kernel:        c02dff39 c03ded20 c0119b9e
f7a3ea64 f72fea30 00000001 c0119d27 00000282
Jan 19 22:06:45 machine3 kernel: Call Trace:
Jan 19 22:06:45 machine3 kernel:  [flush_all_requests+28/85]
flush_all_requests+0x1c/0x55
Jan 19 22:06:45 machine3 kernel:  [user_req_stop_thread+117/223]
user_req_stop_thread+0x75/0xdf
Jan 19 22:06:45 machine3 kernel:  [__sys_tux+349/1736] __sys_tux+0x15d/0x6c8
Jan 19 22:06:45 machine3 kernel:  [lock_timer_base+25/51]
lock_timer_base+0x19/0x33
Jan 19 22:06:45 machine3 kernel:  [try_to_del_timer_sync+16/77]
try_to_del_timer_sync+0x10/0x4d
Jan 19 22:06:45 machine3 kernel:  [try_to_del_timer_sync+71/77]
try_to_del_timer_sync+0x47/0x4d
Jan 19 22:06:45 machine3 kernel:  [tux_exit+9/12] tux_exit+0x9/0xc
Jan 19 22:06:45 machine3 kernel:  [do_exit+370/733] do_exit+0x172/0x2dd
Jan 19 22:06:45 machine3 kernel:  [sys_exit_group+0/17]
sys_exit_group+0x0/0x11
Jan 19 22:06:45 machine3 kernel:  [syscall_call+7/11] syscall_call+0x7/0xb
Jan 19 22:06:45 machine3 kernel: Code: 00 00 8d 59 d8 f0 0f ba 71 20 00
f0 0f ba 71 24 00 8b 11 8b 41 04 89 42 04 89 10 89 49 04 89 09 c6 86 8c
01 00 00 01 fb 8b 43 6c <c7> 40 20 00 00 00 00 c7 40 24 00 00 00 00 80
bb ec 00 00 00 00
Jan 19 22:06:45 machine3 kernel:  <1>Fixing recursive fault but reboot
is needed!
Jan 19 22:06:45 machine3 kernel: TUX: thread 1 stopped.