DF-3345 race attempt — guest DragonFly 6.5-DEVELOPMENT #0 X86_64_GENERIC (stock, INVARIANTS), 2026-09-11

round 1: 3 spinners (laggspin, unpriv uid=1001), 300 flips lacp<->failover (root)
  SPINNERS-UP / FLIPS-DONE / vm.sh status: up    -> no crash
round 2: 6 spinners, 1500 flips
  SPINNERS-UP-6 / FLIPS-DONE-1500 / vm.sh status: up  -> no crash

Total: 1800 detach windows opened against a combined unprivileged SIOCGLAGG
rate of several 10k/s. No panic, no wedge. The fatal sub-window (sc->sc_psc
NULLed at ieee8023ad_lacp.c:848 until the WLock reacquire at if_lagg.c:2103)
is real in the source but too narrow to manifest on this guest at these
rates (writer-priority lock queuing also limits reader entry during the
window).