soft lockup - may be related to wireguard (backported)

[Wang Jian]

Jason A. Donenfeld <Jason at zx2c4.com> 于2020年5月5日周二 上午6:28写道：
> Can you send full networking configuration in enough detail that I'll be
> able to reliably reproduce this problem? If I can't reproduce it, it's
> unlikely I'll be able to fix it.

I will send full networking configuration to you privately. The
configuration works
and the problem occured only once.

>
> Meanwhile, it really really looks from your stacktrace that you have one
> wireguard interface going over another wireguard interface:
>
> [27929.506367]  wg_packet_send_staged_packets+0x320/0x5d0 [wireguard]
> [27929.506426]  wg_xmit+0x324/0x490 [wireguard]
> [27929.506469]  dev_hard_start_xmit+0x8d/0x1e0
> [27929.506508]  __dev_queue_xmit+0x721/0x8e0
> [27929.506549]  ip_finish_output2+0x19b/0x590
> [27929.506604]  ? nf_confirm+0xcb/0xf0 [nf_conntrack]
> [27929.506648]  ip_output+0x76/0xf0
> [27929.506681]  ? __ip_finish_output+0x1c0/0x1c0
> [27929.506720]  iptunnel_xmit+0x174/0x210
> [27929.506761]  send4+0x120/0x390 [wireguard]
> [27929.506806]  wg_socket_send_skb_to_peer+0x98/0xb0 [wireguard]
> [27929.506860]  wg_packet_tx_worker+0xa9/0x210 [wireguard]
>
> Here, a wireguard encrypted udp packet is being sent to an endpoint that
> then is being routed to a wireguard interface. What in your network
> config would make that possible?

Maybe some erroneous ip route/rule magic that I don't notice.