13-current panic

Hi,
I  have multiple servers  running 13-CURRENT and after upgrade to r368448
the following panic began to appear on them:

vpan1c() at vpanic.Ox1b2/frame Oxfffffe019b32ffa0
panic() at panic.0x43/frame Oxfffffe019330000
trap_fatal() at trap_fatal.0x387/frame Oxfffffe019b330060
trap_pfault() at trap_pfault.0x4f/frame Oxfffffe019b3300c0
trap() at trap.0x27d/frame Oxfffffe019b3301d0
calltrap() at calltrap+0x8/frame Oxfffffe019b3301d0
--- trap 0xc. rip = Oxffffffff80c8b3c8. rsp = Oxfffffe019b3302a0, rbp =
Oxfffffe
019b330310 ---
m_copydata() at m_copydata+0x58/frame Oxfffffe019b330310
tcp_output() at tcp_output+0x100b/frame Oxfffffe019b3304b0
tcp_do_segment() at tcp_do_segment+0x2867/frame Oxfffffe019b3305a0
tcp_input() at tcp_input.Oxabe/frame Oxfffffe019b3306d0
ip_input() at ip_input+0x125/frame Oxfffffe019b330760
netisr_dispatch_src() at netisr_dispatch_src+0xca/frame Oxfffffe019b3307b0
ether_demux() at ether demux+0x138/frame Oxfffffe019b3307e0
ether_nh_input() at ether_nh_input+0x351/frame Oxfffffe019b330840
netisr_dispatch_src() at netisr dispatch_src+0xca/frame Oxfffffe019b330890
ether_input() at ether_input+0x69/frame Oxfffffe019b3308f0
tcp_flush_out_le() at tcp_flush_out_le+0x211/frame Oxfffffe019b330910
tcp_push_and_replace() at tcp_push_and_replace+0x30/frame
Oxfffffe019b330950
tcp_lro_flush() at tcp_lro_flush+0x4c/frame Oxfffffe019b330980
tcp_lro_flush_all() at tcp_lro_flush_all+0x13b/frame Oxfffffe019b3309c0
iflib_rxeof() at iflib_rxeof+Oxc7a/frame Oxfffffe019b330ac0
_task_fn_rx() at _task_fn_rx+0x72/frame Oxfffffe019b330b00
gtaskqueue_run_locked() at gtaskqueue_run_locked+0x15d/frame
Oxfffffe019b330b80
gtaskqueue thread_loop() at gtaskqueue thread loop+0xac/frame
Oxfffffe019b330bb0
fork_exit() at fork_exit+0x7e/frame Oxfffffe019b330bf0
fork trampoline() at fork_trampoline+0xe/frame Oxfffffe019b330bf0
-- trap O. rip = O. rsp = O. rbp = 0 ---

it is fileservers with zfs+nginx, higher is the result of recognizing
picture to text, just in case (there are was many recognision mistakes)
screenshot:
https://gyazo.com/116e9666daf0dac6d09628d1585596fa

I can run commands in the debugger when panic reappears if needed