crash - kernel or postgres?

hi all,
today my server crashes. (syslog see below)
i was able to connect to but the machines behaviour was strange.
load was above 152. i couldnt stop/kill the postmaster process. ps just
hangs in the middle of the processlist.
i suspect to optimistic shared memory settings in sysctl.conf for the
reason, but i am not shure.
anyone has similar experiences or is it a linux/kernel related problem?

thanks
thilo hille

syslog ouput:
kernel BUG at page_alloc.c:87!
invalid operand: 0000
Kernel 2.4.9-31
CPU: 0
EIP: 0010:[__free_pages_ok+64/784] Not tainted
EIP: 0010:[<c012beb4>] Not tainted
EFLAGS: 00010286
EIP is at __free_pages_ok [kernel] 0x40
eax: 0000001f ebx: c1cc2a4c ecx: 00000001 edx: 000018a2
esi: c1cc2a4c edi: 00000000 ebp: 00000000 esp: d6aabe78
ds: 0018 es: 0018 ss: 0018
Process postmaster (pid: 26160, stackpage=d6aab000)
Stack: c022ede7 00000057 c1cb9080 2cb04007 00400000 0008c000 c0213cac
c1cc2a4c
c1cc2a4c 00400000 00370000 c012cdcd 0008c000 00000058 00000018
00000018
c1cc2a4c 00000000 c0121b52 c1cc2a4c 00000058 e3fcadc0 00000000
46000000
Call Trace: [IRQ0x0f_interrupt+110759/136192] .rodata.str1.1 [kernel] 0x2042
Call Trace: [<c022ede7>] .rodata.str1.1 [kernel] 0x2042
[call_do_IRQ+5/13] call_do_IRQ [kernel] 0x5
[<c0213cac>] call_do_IRQ [kernel] 0x5
[free_page_and_swap_cache+193/200] free_page_and_swap_cache [kernel] 0xc1
[<c012cdcd>] free_page_and_swap_cache [kernel] 0xc1
[zap_page_range+506/704] zap_page_range [kernel] 0x1fa
[<c0121b52>] zap_page_range [kernel] 0x1fa
[tcp_close+1360/1372] tcp_close [kernel] 0x550
[<c01dd490>] tcp_close [kernel] 0x550
[do_page_fault+349/1084] do_page_fault [kernel] 0x15d
[<c01119c5>] do_page_fault [kernel] 0x15d
[do_page_fault+453/1084] do_page_fault [kernel] 0x1c5
[<c0111a2d>] do_page_fault [kernel] 0x1c5
[exit_mmap+176/276] exit_mmap [kernel] 0xb0
[<c01240ac>] exit_mmap [kernel] 0xb0
[mmput+84/108] mmput [kernel] 0x54
[<c01136f8>] mmput [kernel] 0x54
[do_exit+179/492] do_exit [kernel] 0xb3
[<c0117707>] do_exit [kernel] 0xb3
[filp_close+78/88] filp_close [kernel] 0x4e
[<c013198a>] filp_close [kernel] 0x4e
[do_page_fault+0/1084] do_page_fault [kernel] 0x0
[<c0111868>] do_page_fault [kernel] 0x0
[system_call+51/56] system_call [kernel] 0x33
[<c0106e0f>] system_call [kernel] 0x33

Code: 0f 0b 5d 58 89 d8 2b 05 ac ad 31 c0 8d 04 40 8d 04 80 89 c2