kernel BUG at slab.c:1263! (2.4.19)

Hello,

after few days of working appeared in dmesg
kernel 2.4.19 with grsecurity patch, ext3, reiserfs, 1G mem, highmem enabled. machine still alive, it seems working normal.

kernel BUG at slab.c:1263!

invalid operand: 0000
CPU:    0
EIP:    0010:[<c012b21e>]    Not tainted
EFLAGS: 00010012
eax: c2a5e7ff   ebx: c1c0f700   ecx: 00000001   edx: 00000001
esi: c2a5e000   edi: c2a5e049   ebp: 00012800   esp: d9c3be64
ds: 0018   es: 0018   ss: 0018
Process thttpd (pid: 9414, stackpage=d9c3b000)
Stack: eff8fd54 c031d060 000001f0 c80a32f8 00000800 c2a5e049 00000246
c01ffa91 
       0000069c 000001f0 c80a3220 c80a3220 c80a3220 c0215c1a 00000660
000001f0 
       c80a3220 d9c3bf80 d9c3bf48 ef9b6e4c c64b2f40 caf9db18 c021ff8a
c80a3258 
Call Trace:    [<c01ffa91>] [<c0215c1a>] [<c021ff8a>] [<c022f466>]

[<c01fca95>]
[<c01fccbe>] [<c0133ee6>] [<c010856f>]

Code: 0f 0b ef 04 60 6c 25 c0 f7 c5 00 04 00 00 74 36 b8 a5 c2 0f

after ksymoops

Trace; c01ffa91 <alloc_skb+d1/188>
Trace; c0215c1a <tcp_sendmsg+20a/106c>
Trace; c021ff8a <tcp_write_xmit+20a/2c0>
Trace; c022f466 <inet_sendmsg+3a/40>
Trace; c01fca95 <sock_sendmsg+69/88>
Trace; c01fccbe <sock_write+b2/bc>
Trace; c0133ee6 <sys_write+96/f0>
Trace; c010856f <system_call+33/38>

Code; c012b21e <kmalloc+15a/1e4>
00000000 <_EIP>:
Code; c012b21e <kmalloc+15a/1e4> <=====
0: 0f 0b ud2a <=====
Code; c012b220 <kmalloc+15c/1e4>
2: ef out %eax,(%dx)
Code; c012b221 <kmalloc+15d/1e4>
3: 04 60 add $0x60,%al
Code; c012b223 <kmalloc+15f/1e4>
5: 6c insb (%dx),%es:(%edi)
Code; c012b224 <kmalloc+160/1e4>
6: 25 c0 f7 c5 00 and $0xc5f7c0,%eax
Code; c012b229 <kmalloc+165/1e4>
b: 04 00 add $0x0,%al
Code; c012b22b <kmalloc+167/1e4>
d: 00 74 36 b8 add %dh,0xffffffb8(%esi,%esi,1)
Code; c012b22f <kmalloc+16b/1e4>
11: a5 movsl %ds:(%esi),%es:(%edi)
Code; c012b230 <kmalloc+16c/1e4>
12: c2 0f 00 ret $0xf

SY, Vladimir