# FreeBSD 7.2: Page fault while in kernel mode



## asg (Aug 5, 2009)

Hi,

I have a problem with one of my servers running

```
FreeBSD encephalon.de 7.2-RELEASE-p3 FreeBSD 7.2-RELEASE-p3 #4: Mon Aug  3 10:51:13 CEST 2009     asg@encephalon.de:/usr/obj/usr/src/sys/GRUNIX  amd64
```

2GB of RAM
gmirror 

I started to copy a jail via cpdup and afterward bzip2 the copy. 
While this was running, the system did a spontaneus reboot. 


```
Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
fault virtual address   = 0xfffffffe80a52ff8
fault code              = supervisor read data, page not present
instruction pointer     = 0x8:0xffffffff805330b7
stack pointer           = 0x10:0xfffffffebec6ba30
frame pointer           = 0x10:0xfffffffe807232c0
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 63464 (postgres)
trap number             = 12
panic: page fault
cpuid = 1
Uptime: 16h7m0s
Physical memory: 2003 MB
Dumping 468 MB: 453 437 421 405 389 373 357 341 325 309 293 277 261 245 229 213 197 181 165 149 133 117 101 85 69 53 37 21 5
```

Does anyone know what could be the problem? 
In the past the server had also some spontaneus reboots without doing the described job. 

I have a couple of jails running on that system (with separate postgres running in two jails). 



Thanks in advance.

Cheers,

Axel


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## SirDice (Aug 5, 2009)

The server might have faulty memory, you may want to check that.


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## asg (Aug 5, 2009)

Well, i run memtest a couple of times, seems to be fine. 
I do not have physical access to the machine, so I can not try some other ram modules... :-(


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## ale (Aug 5, 2009)

AFAIK "Fatal trap 12" are not caused by faulty memory.
Get a core dump and send a pr with the backtrace.
http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug.html


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## MG (Aug 5, 2009)

Does bzip2 handle the special file flags in your jail tree correctly? I assume the jail contains a FreeBSD system tree.
It can be anything, this is just a guess.

chflags -R noschg <dir>   #removes all flags in <dir>.

If the reboot happens at random moments it,s probably a hardware problem.


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