kernel BUG at kernel/exit.c:842! (2.6.9, PoPToP and ppp_mppe)

From: Ray Van Dolson
Date: Tue Nov 09 2004 - 01:12:39 EST


Apologies for creating a new thread for this. This seems to be a different
"oops" than my last thread...

My current setup is a Fedora Core 2 box with Kernel 2.6.9-1.1_FC2 + the
ppp_mppe patch by Frank Cusack from the pppd 2.4.3 sources. This module
is what is taining the kernel. All the other modules are stock kernel
modules.

After about 72 hours or so of runtime on a very busy Poptop server (~750
users or so), I begin seeing a few "Neighbour table overflow" error messages
in my /var/log/messages file. Things seem to continue running OK however,
but eventually the following oops shows up:

kernel BUG at kernel/exit.c:842!
invalid operand: 0000 [#1]
SMP
Modules linked in: sch_tbf(U) ppp_async(U) crc_ccitt(U) ppp_mppe(U) ppp_generic(U) slhc(U) ipt_limit(U) ipt_REJECT(U) ipt_multiport(U) iptable_filter(U) iptable_nat(U) ip_conntrack(U) ip_tables(U) sunrpc(U) e100(U) mii(U) sg(U) scsi_mod(U) microcode(U) dm_mod(U) ohci_hcd(U) button(U) battery(U) ac(U) ext3(U) jbd(U)
CPU: 2
EIP: 0060:[<02121d10>] Tainted: P VLI
EFLAGS: 00010246 (2.6.9-1.1_FC2custom)
EIP is at do_exit+0x3b3/0x3bd
eax: 00000000 ebx: 26506560 ecx: 26506000 edx: 0381dd60
esi: 41fec340 edi: 26506030 ebp: 00001000 esp: 23b82f98
ds: 007b es: 007b ss: 0068
Process pppd (pid: 27091, threadinfo=23b82000 task=26506030)
Stack: 0d611e00 00001000 23b82000 23b82000 02121e05 00001000 23b82fc4 00000010
f6f32684 23b82000 fffec200 00000010 00000000 00000000 00000010 f6f32684
fef87938 000000fc 0000007b 0000007b 000000fc f6fa37a2 00000073 00000246
Call Trace:
[<02121e05>] sys_exit_group+0x0/0xd
Code: c1 e0 07 8d 04 10 ff 88 00 01 00 00 83 3a 02 75 0b 8b 82 08 11 00 00 e8 d8 95 ff ff 89 6f 7c 89 f8 e8 88 f5 ff ff e8 bc 74 19 00 <0f> 0b 4a 03 96 09 2d 02 eb fe 53 85 c0 89 d3 74 05 e8 35 ab ff
<1>Unable to handle kernel NULL pointer dereference at virtual address 00000024
printing eip:
0211ddb0
*pde = 00004001
Oops: 0000 [#2]
SMP
Modules linked in: sch_tbf(U) ppp_async(U) crc_ccitt(U) ppp_mppe(U) ppp_generic(U) slhc(U) ipt_limit(U) ipt_REJECT(U) ipt_multiport(U) iptable_filter(U) iptable_nat(U) ip_conntrack(U) ip_tables(U) sunrpc(U) e100(U) mii(U) sg(U) scsi_mod(U) microcode(U) dm_mod(U) ohci_hcd(U) button(U) battery(U) ac(U) ext3(U) jbd(U)
CPU: 2
EIP: 0060:[<0211ddb0>] Tainted: P VLI
EFLAGS: 00010286 (2.6.9-1.1_FC2custom)
EIP is at mm_release+0x33/0x70
eax: 00000000 ebx: 26506030 ecx: 00000000 edx: 00000000
esi: f6ff6828 edi: 00000000 ebp: 0000000b esp: 23b82e50
ds: 007b es: 007b ss: 0068
Process pppd (pid: 27091, threadinfo=23b82000 task=26506030)
Stack: 00000000 00000000 23b82f64 26506030 02121a20 23b82000 23b82f64 00000000
022c9112 021064a2 0000000b 23b82f64 022c9112 00000000 000000ff 0000000b
00000000 02106784 00001000 23b82f64 00000000 02106784 00001000 02106850
Call Trace:
[<02121a20>] do_exit+0xc3/0x3bd
[<021064a2>] do_divide_error+0x0/0xea
[<02106784>] do_invalid_op+0x0/0xd5
[<02106784>] do_invalid_op+0x0/0xd5
[<02106850>] do_invalid_op+0xcc/0xd5
[<0211bff5>] load_balance+0x27/0x135
[<02121d10>] do_exit+0x3b3/0x3bd
[<022b9a4a>] schedule+0x87e/0x8aa
[<0217e45d>] proc_delete_inode+0x0/0x61
[<022b9a4a>] schedule+0x87e/0x8aa
[<02121d10>] do_exit+0x3b3/0x3bd
[<02121e05>] sys_exit_group+0x0/0xd
Code: 8b 90 14 01 00 00 31 c0 8e e0 8e e8 85 d2 74 11 c7 83 14 01 00 00 00 00 00 00 89 d0 e8 b5 ea ff ff 8b b3 1c 01 00 00 85 f6 74 38 <8b> 47 24 48 7e 32 c7 83 1c 01 00 00 00 00 00 00 89 e2 89 f1 c7
<1>Unable to handle kernel NULL pointer dereference at virtual address 00000024
printing eip:
0211ddb0
*pde = 00004001
Oops: 0000 [#3]
SMP
Modules linked in: sch_tbf(U) ppp_async(U) crc_ccitt(U) ppp_mppe(U) ppp_generic(U) slhc(U) ipt_limit(U) ipt_REJECT(U) ipt_multiport(U) iptable_filter(U) iptable_nat(U) ip_conntrack(U) ip_tables(U) sunrpc(U) e100(U) mii(U) sg(U) scsi_mod(U) microcode(U) dm_mod(U) ohci_hcd(U) button(U) battery(U) ac(U) ext3(U) jbd(U)
CPU: 2
EIP: 0060:[<0211ddb0>] Tainted: P VLI
EFLAGS: 00010286 (2.6.9-1.1_FC2custom)
EIP is at mm_release+0x33/0x70
eax: 00000000 ebx: 26506030 ecx: 00000000 edx: 00000000
esi: f6ff6828 edi: 00000000 ebp: 0000000b esp: 23b82cc8
ds: 007b es: 007b ss: 0068

The system does not die immediately, and in fact I can still access the web
server, and establish a pptp tunnel but no traffic passes. Likewise I can
get a password prompt from the console, switch to different terminals etc
but stuff just seems to hang and generally act weird. Eventually I am forced
to hard reset the box since I cannot log in to run /sbin/reboot.

I am beginning to wonder if somehow the ppp_mppe module just simply does not
like the Dual Xeon processors in this HP DL140 server or if this is actually
a legitimate bug...

Any suggestions or further information I can provide? It looks like the
Fedora project has released a newer 2.6.9 based kernel, so I may give that
a try, and also may try just building a kernel from the sources off of
kernel.org.

Thanks for any help.
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