DF-5848 run log — stock panic + fixed survival (2026-10-26)

STOCK PANIC (fresh, this session):
  Client: /tmp/df5848_pipe 90  (root, reserved src port 791, TCP_NODELAY)
  Server: kernel nfsd (nfsd -t -n 4), 127.0.0.1:2049, /etc/exports
  Result: panic well inside the 90 s budget (panic-run1.txt):
    panic: assertion "m->m_type == MT_DATA" failed in m_dup_data at
      /usr/src/sys/kern/uipc_mbuf.c:1806
    m_dup_data() at m_dup_data+0x129
    nfs_realign.isra.3() at nfs_realign.isra.3+0x48
    nfsrv_rcv() at nfsrv_rcv+0x4d0
    sys_nfssvc() at sys_nfssvc+0x13bb
    syscall2() at syscall2+0x11e
  Identical stack to the original stock capture (incidental_nfsd_panic.txt,
  DF-3072 batch, kernel #0 Jul 2). The client never printed DONE (guest
  died mid-run); the client's own output is immaterial - the panic is the
  observation.

FIXED SURVIVAL (tri-fix build #2: Mon Oct 26 06:04:19 UTC 2026):
  Client: /tmp/df5848_pipe 300 (identical binary and load shape)
  Result (full output):
    df5848_pipe: connected to 127.0.0.1:2049 (src port 791), streaming
      misaligned LASTFRAG records for 300s
    df5848_pipe: 285s elapsed, 127803 single records, 255600 burst
      records, 127286 reply reads
    df5848_pipe: 290s elapsed, 130053 single records, 260096 burst
      records, 129533 reply reads
    df5848_pipe: 295s elapsed, 132295 single records, 264576 burst
      records, 131771 reply reads
    df5848_pipe: DONE single=134493 burst=268976 drained=133968
  -> 134k individually-segmented misaligned records + 269k pipelined
     burst records; nfsd serviced all replies (134k reply drains);
     ZERO panics/assertions; guest healthy.

  Build: make -j6 nativekernel RC=0 -Werror clean (uipc_mbuf.c relaxed
  invariant + DF-5846/DF-5847 fixes in disjoint files).