iflib_record_started(0)... done. epoch_init_smp(0)... done. subsystem fffffff print_caddr_t(&wit_warn)... WARNING: WITNESS option enabled, expect reduced performance. done. start_periodic_resettodr(0)... done. oktousecallout(0)... done. ~~? ~! shell ~< receive file from remote host ~> send file to remote host ~t take file from remote UNIX ~p put file to remote UNIX ~| pipe remote file ~$ pipe local command to remote host ~C connect program to remote host ~c change directory ~. exit from tip ~^D exit from tip ~^Y suspend tip (local+remote) ~^Z suspend tip (local only) ~s set variable ~v list variables ~? get this summary ~# send break ~spin lock 0xe000000000bbac18 (witness lock) held by 0xc00000000a623560 (tid 100073) too long timeout stopping cpus panic: spin lock held too long cpuid = 0 time = 1571163983 KDB: stack backtrace: 0xe000000043722da0: at kdb_backtrace+0x60 0xe000000043722eb0: at vpanic+0x1d8 0xe000000043722f60: at panic+0x40 0xe000000043722f90: at _mtx_lock_indefinite_check+0xe8 0xe000000043723010: at _mtx_lock_spin_cookie+0x110 0xe0000000437230a0: at __mtx_lock_spin_flags+0x17c 0xe000000043723150: at witness_checkorder+0x3b8 0xe000000043723260: at _sx_xlock+0x90 0xe000000043723300: at usbd_ctrl_lock+0x64 0xe000000043723350: at usbd_do_request_flags+0x1b0 0xe000000043723480: at usbd_req_get_port_status+0x54 0xe0000000437234b0: at uhub_read_port_status+0x94 0xe000000043723550: at uhub_explore+0x210 0xe0000000437236e0: at usb_bus_explore+0x160 0xe000000043723760: at usb_process+0x170 0xe000000043723820: at fork_exit+0xc4 0xe0000000437238c0: at fork_trampoline+0x18 0xe0000000437238f0: at -0x4 KDB: enter: panic [ thread pid 13 tid 100044 ] Stopped at kdb_enter+0x78: ori r0, r0, 0x0 db> db> db> db> db> db> db> db>