When trying to print a file, I got

uvm_fault(0xc056c000, 0, 0, 1) -> 0xe
db> bt
usb_transfer_complete(c1ab9100,2,cc3f0f4c,c02924df,c30e1880) at
netbsd:usb_transfer_complete+0x16f
uhci_abort_xfer(c1ab9100,f,cc3f0f8c,c03cfd48,3800d8db) at
netbsd:uhci_abort_xfer+0x19d
uhci_timeout_task(c1ab9100,0,0,cc3e0210,cc3d7660) at
netbsd:uhci_timeout_task+0x28
usb_task_thread(cc3e0210,5eb000,5f4000,0,c0100321) at
netbsd:usb_task_thread+0x64

  -jm