mpd5/Netgraph issues after upgrading to 7.4

[Przemyslaw Frasunek]

Dear All,

unfortunately, one of my mpd5 PPPoE access servers started panicing every few
hours.

I'm running recent 8.3-STABLE (as of 23th May) with WITNESS, INVARIANTS and
DEBUG_MEMGUARD compiled. Unfortunately, I'm unable to catch crashdump. For some
reason, it is not saved on dumpdev.

The only thing I have is panic string:

Fatal trap 9: general protection fault while in kernel mode
cpuid = 2; apic id = 02
instruction pointer      = 0x20:0xffffffff804b4e2d
stack pointer            = 0x28:0xffffff8185386560
frame pointer            = 0x28:0xffffff81853865d0
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          = 2832 (mpd5)
trap number              = 9

According to "objdump -d", the fault address points to prelist_remove().

I tried to replace all of hardware, but it still panics in the same way. I would
be really grateful for any hints.

dmesg output: http://www.frasunek.com/tmp/dmesg.txt
kernel config: http://www.frasunek.com/tmp/kernel.txt