I run a 24/7 server on my Slackware 10.2 box. It was running kernel 2.6.13 kernel for 3 months. This weekend I realized that when it boots it would boot normally and then a weird message went by that said:

call trace

and had a bunch of strange numbers below it. I didn't used to get this and it worried me. I compiled kernel 2.4.32 and now when I boot with that kernel I don't get the funny start up message.

Anybody know what that means?

What appeared right before it in log? I guess some program crashed on startup, leaving inner function call trace. It is information inner to program (and useful for debugging/bug reporting sometimes), but it can be interesting for you which program crashed. Or ignore it - if you are OK with 2.4... For some time, until you will upgrade..

My wireless NIC module is kernel specific and I had to uninstall it from the 2.6.13 kernel in order to get it to work in the 2.4.32 kernel. I was also worried that somebody had cracked into my server and made it into a sleeping zombie-that kernel has no NIC now...anyway, I will boot into the 2.6.13 kernel when I get home and post the relevant part of dmesg.

ok, here's a snippet from dmesg in kernel 2.6.13 with a message about Call Trace which doesn't appear in dmesg in kernel 2.4.32:

Fusion MPT base driver 3.03.02
Copyright (c) 1999-2005 LSI Logic Corporation
Fusion MPT SPI Host driver 3.03.02
Fusion MPT FC Host driver 3.03.02
usbmon: debugfs is not available
usbcore: registered new driver hiddev
usbcore: registered new driver usbhid
drivers/usb/input/hid-core.c: v2.01:USB HID core driver
mice: PS/2 mouse device common for all mice
NET: Registered protocol family 2
input: AT Translated Set 2 keyboard on isa0060/serio0
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 4096 (order: 3, 32768 bytes)
TCP bind hash table entries: 4096 (order: 2, 16384 bytes)
TCP: Hash tables configured (established 4096 bind 4096)
TCP reno registered
TCP bic registered
Initializing IPsec netlink socket
NET: Registered protocol family 1
NET: Registered protocol family 17
Using IPI Shortcut mode
RAMDISK: Compressed image found at block 0
VFS: Mounted root (ext2 filesystem).
kmem_cache_create: duplicate cache reiser_inode_cache
------------[ cut here ]------------
kernel BUG at mm/slab.c:1488!
invalid operand: 0000 [#1]
Modules linked in: reiserfs
CPU: 0
EIP: 0060:[<c013affd>] Not tainted VLI
EFLAGS: 00010202 (2.6.13)
EIP is at kmem_cache_create+0x3fd/0x540
eax: c0528fa0 ebx: c1162850 ecx: c12b1f60 edx: c4ac1418
esi: c052a5cb edi: c4ac142b ebp: c12dfae0 esp: c12b1f64
ds: 007b es: 007b ss: 0068
Process busybox (pid: 858, threadinfo=c12b0000 task=c121a550)
Stack: c0000000 fffffffc 00000004 00000034 c4ac8400 c12b0000 c0000000 c12b0000
c4aa721d c4ac1418 00000190 00000000 00020000 c4aa71b0 00000000 c4852006
c4ac8400 c0130472 b7f76000 00000100 00000000 c0102ea9 b7f76000 0003bd53
Call Trace:
[<c4aa721d>] init_inodecache+0x1d/0x40 [reiserfs]
[<c4aa71b0>] init_once+0x0/0x50 [reiserfs]
[<c4852006>] init_reiserfs_fs+0x6/0x52 [reiserfs]
[<c0130472>] sys_init_module+0x122/0x1b0
[<c0102ea9>] syscall_call+0x7/0xb
Code: 04 00 74 ec e9 49 01 00 00 90 8d 74 26 00 8b 4c 24 24 51 68 a0 8f 52 c0 e8 f1 d7 fd ff 58 5a ff 05 6c 02 76 c0 0f 8e 9a 13 00 00 <0f> 0b d0 05 82 85 52 c0 e9 70 ff ff ff 8d b6 00 00 00 00 8b 41
<5>ReiserFS: hde1: found reiserfs format "3.6" with standard journal
ReiserFS: hde1: using ordered data mode
ReiserFS: hde1: journal params: device hde1, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30
ReiserFS: hde1: checking transaction log (hde1)
ReiserFS: hde1: Using r5 hash to sort names

It is a kernel bug, as the heading indicates.

oh-what caused it? I didn't have that bug months ago when I first installed it.