Kernel panic

Device: Newifi-D2
OpenWrt version: 19.07.1 r10911-c155900f66

[27226.008011] mtk_soc_eth 1e100000.ethernet eth0: port 3 link down
[27228.980608] mtk_soc_eth 1e100000.ethernet eth0: port 3 link up
[60114.949063] mtk_soc_eth 1e100000.ethernet eth0: port 1 link up
[60146.647874] mtk_soc_eth 1e100000.ethernet eth0: port 2 link down
[60155.584307] mtk_soc_eth 1e100000.ethernet eth0: port 2 link up
[60223.819350] ------------[ cut here ]------------
[60223.824060] WARNING: CPU: 2 PID: 19 at backports-4.19.98-1/net/mac80211/tx.c:4270 0x8f7ac914 [mac80211@8f780000+0x6c840]
[60223.834925] Modules linked in: pppoe ppp_async pppox ppp_generic nf_conntrack_ipv6 mt76x2e mt76x2_common mt76x02_lib mt7603e mt76 mac80211 iptable_nat ipt_REJECT ipt_MASQUERADE cfg80211 xt_time xt_tcpudp xt_state xt_nat xt_multiport xt_mark xt_mac xt_limit xt_conntrack xt_comment xt_TCPMSS xt_REDIRECT xt_LOG xt_FLOWOFFLOAD xt_CT slhc nf_reject_ipv4 nf_nat_redirect nf_nat_masquerade_ipv4 nf_conntrack_ipv4 nf_nat_ipv4 nf_nat nf_log_ipv4 nf_flow_table_hw nf_flow_table nf_defrag_ipv6 nf_defrag_ipv4 nf_conntrack_rtcache nf_conntrack iptable_mangle iptable_filter ip_tables crc_ccitt compat ledtrig_usbport nf_log_ipv6 nf_log_common ip6table_mangle ip6table_filter ip6_tables ip6t_REJECT x_tables nf_reject_ipv6 leds_gpio xhci_plat_hcd xhci_pci xhci_mtk xhci_hcd gpio_button_hotplug usbcore nls_base usb_common
[60223.905881] CPU: 2 PID: 19 Comm: ksoftirqd/2 Not tainted 4.14.167 #0
[60223.912213] Stack : 00000000 00000000 00000000 8f1309b0 00000000 00000000 00000000 00000000
[60223.920557] 00000000 00000000 00000000 00000000 00000000 00000001 8fc83b70 ac07f5be
[60223.928898] 8fc83c08 00000000 00000000 00006798 00000038 8049b6d8 00000008 00000000
[60223.937235] 00000000 80550000 000dd299 00000000 8fc83b50 00000000 00000000 8f7e7ba0
[60223.945575] 8f7ac914 000010ae 8f596480 8f1309b0 00000003 802ac758 00000008 806b0008
[60223.953916] ...
[60223.956355] Call Trace:
[60223.956410] [<8049b6d8>] 0x8049b6d8
[60223.962314] [<8f7ac914>] 0x8f7ac914 [mac80211@8f780000+0x6c840]
[60223.968221] [<802ac758>] 0x802ac758
[60223.971700] [<8000c1a0>] 0x8000c1a0
[60223.975174] [<8000c1a8>] 0x8000c1a8
[60223.978650] [<80484544>] 0x80484544
[60223.982140] [<8f7ac914>] 0x8f7ac914 [mac80211@8f780000+0x6c840]
[60223.988030] [<800729c4>] 0x800729c4
[60223.991503] [<8002e5f8>] 0x8002e5f8
[60223.994984] [<8f7ac914>] 0x8f7ac914 [mac80211@8f780000+0x6c840]
[60224.000905] [<8002e6e0>] 0x8002e6e0
[60224.004381] [<80053adc>] 0x80053adc
[60224.007858] [<8f7ac914>] 0x8f7ac914 [mac80211@8f780000+0x6c840]
[60224.013757] [<8f7af14c>] 0x8f7af14c [mac80211@8f780000+0x6c840]
[60224.019657] [<80067be8>] 0x80067be8
[60224.023138] [<80017f6c>] 0x80017f6c
[60224.026644] [<8ec57b10>] 0x8ec57b10 [mt76x02_lib@8ec50000+0x9640]
[60224.032723] [<8f7af5b0>] 0x8f7af5b0 [mac80211@8f780000+0x6c840]
[60224.038639] [<8ec57b50>] 0x8ec57b50 [mt76x02_lib@8ec50000+0x9640]
[60224.044720] [<8f7b6270>] 0x8f7b6270 [mac80211@8f780000+0x6c840]
[60224.050629] [<8f7b634c>] 0x8f7b634c [mac80211@8f780000+0x6c840]
[60224.056529] [<8ec54a48>] 0x8ec54a48 [mt76x02_lib@8ec50000+0x9640]
[60224.062604] [<800329c4>] 0x800329c4
[60224.066083] [<804a24d8>] 0x804a24d8
[60224.069567] [<8004fc60>] 0x8004fc60
[60224.073047] [<8004fc60>] 0x8004fc60
[60224.076525] [<80032c98>] 0x80032c98
[60224.080014] [<8004fe08>] 0x8004fe08
[60224.083492] [<8049da58>] 0x8049da58
[60224.086990] [<8004be88>] 0x8004be88
[60224.090461] [<8004bd58>] 0x8004bd58
[60224.093942] [<8004bd58>] 0x8004bd58
[60224.097419] [<8004bd58>] 0x8004bd58
[60224.100892] [<80006f78>] 0x80006f78
[60224.104376]
[60224.106046] ---[ end trace 9451b22d11d2504d ]---
[60248.509536] mtk_soc_eth 1e100000.ethernet eth0: port 1 link down
[60260.376655] mtk_soc_eth 1e100000.ethernet eth0: port 1 link up
[60287.745437] mtk_soc_eth 1e100000.ethernet eth0: port 1 link down
[72968.373293] mtk_soc_eth 1e100000.ethernet eth0: port 2 link down
[72970.371221] mtk_soc_eth 1e100000.ethernet eth0: port 2 link up
[72988.002931] mtk_soc_eth 1e100000.ethernet eth0: port 2 link down

Start with the reported OpenWrt 19.07.1 kernel log, especially backports-4.19.98-1/net/mac80211/tx.c:4270 and the mt76x2e/mt76x02_lib modules listed in the trace. Reproduce on the Newifi-D2 and determine the trigger for the warning; done means the kernel no longer reports this failure under the same conditions.