=== DF-3144 run (stock kernel) ===
trigger: /root/mount_rw /dev/vn0 /tmp/hpfsmp2 (mount(2) of df3144.img)

VN_OK
--- mount as root (expect HANG in mount(2) at hpfs_cpinit) ---
(no MOUNT_RC ever printed; command:)
  $ timeout 30 ssh dfbsd 'timeout 15 /root/mount_rw /dev/vn0 /tmp/hpfsmp2; echo MOUNT_RC=$?'
  SSH_RC=124   <-- inner timeout(15) COULD NOT kill mount(2); outer ssh killed at 30s

--- post-hang probes ---
  ssh dfbsd 'sh /tmp/df3144_probe.sh' -> 'Connection timed out during banner exchange' (rc=255)
  guest degraded exactly like DF-3143 (sshd starved by the in-kernel bread() spin)