natflow cpu dead loop

[ptpt52]

[   39.275979] pppoe-wan: renamed from ppp0
[  356.584030] rcu: INFO: rcu_sched self-detected stall on CPU
[  356.595149] rcu: 	2-....: (1 GPs behind) idle=1ee/1/0x40000004 softirq=6126/6127 fqs=1042 
[  356.611586] 	(t=2103 jiffies g=7817 q=2502)
[  356.619901] NMI backtrace for cpu 2
[  356.626836] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 5.10.113 #0
[  356.638947] Stack : 809d0000 807d22f8 807d0000 8007bc4c 80840000 8073a5b0 00000000 00000000
[  356.655591]         8140f894 809b0000 80709230 8143ccd8 807d4d87 00000001 8140f838 8f9a0575
[  356.672231]         00000000 00000000 80709230 8140f6d8 ffffefff 00000000 ffffffea 00000000
[  356.688869]         8140f6e4 0000011b 807d99c0 ffffffff 00000000 00000000 00000000 80710000
[  356.705509]         00000000 807d0000 807d0000 807d22f8 00000018 803be648 00000008 809b0008
[  356.722149]         ...
[  356.727014] Call Trace:
[  356.731896] [<800080c0>] show_stack+0x30/0x100
[  356.740740] [<8033bd94>] dump_stack+0x9c/0xcc
[  356.749411] [<803426c8>] nmi_cpu_backtrace+0x104/0x164
[  356.759627] [<8034287c>] nmi_trigger_cpumask_backtrace+0x154/0x184
[  356.771936] [<8008ea7c>] rcu_dump_cpu_stacks+0x128/0x17c
[  356.782504] [<80094dc8>] rcu_sched_clock_irq+0x7bc/0x9a4
[  356.793079] [<8009afc4>] update_process_times+0x78/0xc4
[  356.803490] [<800af7d4>] tick_handle_periodic+0x34/0xd0
[  356.813879] [<8048827c>] gic_compare_interrupt+0x7c/0x9c
[  356.824464] [<80084ac4>] handle_percpu_devid_irq+0xbc/0x19c
[  356.835545] [<8007e5c8>] generic_handle_irq+0x44/0x5c
[  356.845604] [<80358800>] gic_handle_local_int+0x94/0x118
[  356.856166] [<80358894>] gic_irq_dispatch+0x10/0x20
[  356.865864] [<8007e5c8>] generic_handle_irq+0x44/0x5c
[  356.875926] [<806673ec>] do_IRQ+0x1c/0x2c
[  356.883892] [<80358034>] plat_irq_dispatch+0x68/0xf0
[  356.893763] [<80003508>] except_vec_vi_end+0xb8/0xc4
[  356.903706] [<82d45ec0>] natflow_session_learn+0x2780/0x3fac [natflow]

[ptpt52]

natflow 20220517 on mt7621

[ptpt52]

fixed after 18509bc

[ptpt52]

eth0---skb_scrub_packet()-->pppoe-wan--->fwd