# My 8.1-STABLE kernel is CRASHING



## kenorb (Nov 15, 2010)

On Friday my Xorg just frozen for 2 days, when I run ktrace (but it's another issue).
Today after reboot my kernel keep crashing without reason.
I didn't do any changes recently. This kernel was working on that machine with the same configuration.
See attachment for screen error.
Then I tried to boot kernel.old, it didn't work.
It happen each time, what ever which boot mode I'll choose (tried "Safe" Mode, without ACPI, tried unload all modules and boot it clean, etc. - the same).
Finally I tried to load my: kernel.head (other version), I'd some version mismatch problems, but finally with some force I could ignore some mismatch to run temporary Xorg and post the screenshots.
I'll try to recompile my kernel with debug symbols (KDB, DDB, KDB_TRACE; man 4 gdb
Why it suddenly stopped to work? It's a kernel bug?

UPDATE: Sorry, I tried to attach the screenshots, but simply somehow doesn't work on this forum.
So here are the links (each pic different boot):


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## kenorb (Nov 15, 2010)

This could be related?
http://forums.freebsd.org/showthread.php?t=18451
http://forums.freebsd.org/showthread.php?t=18676
http://lists.freebsd.org/pipermail/freebsd-stable/2010-February/055277.html

Maybe this bug?
http://www.mail-archive.com/freebsd-bugs@freebsd.org/msg02620.html


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## eye (Nov 15, 2010)

Boot in verbose mode both kernels (working and non-working) and figure out on which initialization step it fails. OTOH, such an info is usually provided in backtrace.


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## kenorb (Nov 15, 2010)

Compiled the kernel with debug symbols, it happen again. The best is that after panic even debugger is frozen, /var/crash is empty, nothing in messages.

```
> ls /var/crash/
minfree
```
See screenshot:




```
Fatal trap 12: page fault while in kernel mode
fault virtual address = 0x6b73616d
fault code = supervisor read data, page not present
instruction pointer = 0x20:0xffffffff81c8316e
processor eflags = interrupt enabled, resume, IOPL = 0
current process = 0 (swapper)
[thread pid 0 tid 100000 ]
Stopped at RTR0MemObjFree+0x59: cmpl $0x19611210,(%rb%)
db>
```
http://www.unixguide.net/freebsd/faq/18.13.shtml


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## kenorb (Nov 16, 2010)

Re-compiled kernel with debug symbols ann commented out those lines related to VirtualBox:

```
# VirtualBox VM
#vboxdrv_load="YES"
#vboxnetflt_load="YES"
#vboxnetadp_load="YES"
```
Now it boots.
Weird, because I don't have any problems to load those modules manually


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