kernel trap 12 with interrupts disabled

I just got one of these shortly after I rebooted my November 7th
-CURRENT box. DDB doesn't show much interesting.

 kernel trap 12 with interrupts disabled


Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address   = 0xbc04d753
fault code              = supervisor read, page not present
instruction pointer     = 0x8:0xc0685ddf
stack pointer           = 0x10:0xe5f3bca8
frame pointer           = 0x10:0xe5f3bcfc
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = resume, IOPL = 0
current process         = 519 (setiathome)
kernel: type 12 trap, code=0
Stopped at      mi_switch+0xcf: cmpl    0x8(%esi),%ebx
db> tr
mi_switch(c6bbc500,df,c08a3da3,f8,0) at mi_switch+0xcf
ast(e5f3bd48) at ast+0x3f2
doreti_ast() at doreti_ast+0x17

Alas, I didn't have enough free space to capture a core file B-(