A me-too oops from 2.4.19-pre4-ac3

Hello,

I've seen a few of these reports on the list -

I'm running 2.4.19-pre4-ac3 + preemptive and the -aa low latency patch. (Andrew's mini-lowlat)

The box had been up for about 4 days when the
oops happened, while playing quake 3 arena.
No ill effects were noted, the box is still up
and everything appears to be working.

Red Hat 7.2+ updates -
P4b 1600
Genuine Intel P4 mobo
512 MB RAM

Yes, my kernel is tainted with nvidia, but IMHO
the nvidia driver has zero connection with the
oops - So, FWIW, here's the oops:

kernel BUG at page_alloc.c:131!

invalid operand: 0000
CPU:    0
EIP:    0010:[<c012efd7>]    Tainted: P

Using defaults from ksymoops -t elf32-i386 -a i386
EFLAGS: 00013282
eax: 00000000 ebx: c1552120 ecx: c100000c edx: dad607a8
esi: 00000000 edi: 00000000 ebp: 00007000 esp: dda91ed8
ds: 0018 es: 0018 ss: 0018
Process X (pid: 2118, stackpage=dda91000)

Stack: c025f278 c1552120 00000000 00000001 c1552120 00008000 c1552120 c1552120
      00008000 dcba1640 00007000 c0122592 c1552120 1a319027 00000008 
00000000
      48591000 de241484 48589000 00000000 48591000 de241484 00030002 
dc0dab80
Call Trace: [<c0122592>] [<c0125054>] [<c012503d>] [<c0125114>] [<c0106efb>]
Code: 0f 0b 83 00 22 1b 1f c0 c6 43 24 05 8b 43 18 89 f1 83 e0 eb

Trace; c0122592 <zap_page_range+192/260>
Trace; c0125054 <do_munmap+214/2a0>
Trace; c012503d <do_munmap+1fd/2a0>
Trace; c0125114 <sys_munmap+34/50>
Trace; c0106efb <system_call+33/38>
Code; c012efd7 <__free_pages_ok+c7/2a0>
00000000 <_EIP>:

Code;  c012efd7 <__free_pages_ok+c7/2a0>   <=====
  0:   0f 0b                     ud2a      <=====
Code;  c012efd9 <__free_pages_ok+c9/2a0>
  2:   83 00 22                  addl   $0x22,(%eax)
Code;  c012efdc <__free_pages_ok+cc/2a0>
  5:   1b 1f                     sbb    (%edi),%ebx
Code;  c012efde <__free_pages_ok+ce/2a0>
  7:   c0 c6 43                  rol    $0x43,%dh
Code;  c012efe1 <__free_pages_ok+d1/2a0>
  a:   24 05                     and    $0x5,%al
Code;  c012efe3 <__free_pages_ok+d3/2a0>
  c:   8b 43 18                  mov    0x18(%ebx),%eax
Code;  c012efe6 <__free_pages_ok+d6/2a0>
  f:   89 f1                     mov    %esi,%ecx
Code;  c012efe8 <__free_pages_ok+d8/2a0>
 11:   83 e0 eb                  and    $0xffffffeb,%eax