ui_cycle: uid=0
STEP socket node named uicyc
STEP mkpeer UI(U0) S.a<->U0.downstream
STEP named U0 = u0
STEP mkpeer UI(U1) U0.upstream<->U1.downstream
STEP named U1 = u1
STEP rmhook uicyc:a (U0 survives with upstream only)
STEP connect U1.upstream<->U0.downstream -- RING CLOSED
STEP injecting FLOW message to u0:downstream ...
<hang -- sendto() never returns; ssh session dies with the guest>

--- serial console (guest dead in DDB) ---
login: panic: assertion "ref < &td->td_toks_end" failed in lwkt_gettoken at /usr/src/sys/kern/lwkt_token.c:661
cpuid = 0
Trace beginning at frame 0xfffff8011830e7d0
lwkt_gettoken() at lwkt_gettoken+0x3c9 0xffffffff80679779 
lwkt_gettoken() at lwkt_gettoken+0x3c9 0xffffffff80679779 
ng_apply_item() at ng_apply_item+0x47 0xffffffff82601997 
ng_apply_item() at ng_apply_item+0x1f4 0xffffffff82601b44 
ng_apply_item() at ng_apply_item+0x1f4 0xffffffff82601b44 
ng_apply_item() at ng_apply_item+0x1f4 0xffffffff82601b44 
Debugger("panic")

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