login: panic: trying to free NULL pointer
cpuid = 0
Trace beginning at frame 0xfffff8011887f940
_kfree() at _kfree+0x558 0xffffffff806583d8 
_kfree() at _kfree+0x558 0xffffffff806583d8 
ng_iface_constructor() at ng_iface_constructor+0x312 0xffffffff8260bdd2 
ng_make_node() at ng_make_node+0x5f 0xffffffff82600d6f 
ng_apply_item() at ng_apply_item+0x666 0xffffffff82601fb6 
ngthread() at ngthread+0x18 0xffffffff82603488 
Debugger("panic")

CPU0 stopping CPUs: 0x0000003e
 stopped
Stopped at      Debugger+0x7c:  movb    $0,0xbdaf09(%rip)
db>