I am building a system which coordinates the meshing of wireguard devices. Currently, all the devices are running on an embedded platform (AMD Geode LX500) and works as expected. However, when introducing a 64bit KVM host for testing, all the 32bit hosts running on the Geode platform, report the following warning and drop offline temporarily. The CPU usage on KVM host spikes and all the CPU time is spent on the kernel threads servicing the WG interfaces.

I'm using kernel 4.19.41 and have seen the issue with both the last WG snapshot as well building from master.

Is this a bug in WG?

May 10 18:36:25 buildroot kern.warn kernel: WARNING: CPU: 0 PID: 9 at kernel/workqueue.c:1442 __queue_work+0x1d4/0x2aa

May 10 18:36:25 buildroot kern.warn kernel: CPU: 0 PID: 9 Comm: ksoftirqd/0 Tainted: G W 4.19.41-banana #1

May 10 18:36:25 buildroot kern.warn kernel: EIP: __queue_work+0x1d4/0x2aa

May 10 18:36:25 buildroot kern.warn kernel: Code: c1 e8 4e 09 1d 00 c7 05 30 d3 5f c1 00 00 00 00 c7 45 e4 00 00 00 00 e9 76 fe ff ff 8b 3d 80 3c 60 c1 89 78 10 e9 32 ff ff ff <0f> 0b b8 01 00 00 00 e8 1c 82 00 00 a1 a8 9e 5f c1 85 c0 0f 85 3b

May 10 18:36:25 buildroot kern.warn kernel: EAX: 00000000 EBX: cfb63044 ECX: 00000003 EDX: cfb63048

May 10 18:36:25 buildroot kern.warn kernel: ESI: cfdfbb00 EDI: cfab29c0 EBP: cf847d38 ESP: cf847d1c

May 10 18:36:25 buildroot kern.warn kernel: DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068 EFLAGS: 00010086

May 10 18:36:25 buildroot kern.warn kernel: CR0: 80050033 CR2: a7bb5058 CR3: 0eebe000 CR4: 00000090

May 10 18:36:25 buildroot kern.warn kernel: Call Trace:

May 10 18:36:25 buildroot kern.warn kernel: queue_work_on+0x19/0x1d

May 10 18:36:25 buildroot kern.warn kernel: wg_packet_receive+0x4a5/0x557

May 10 18:36:25 buildroot kern.warn kernel: ? send6+0x1fc/0x1fc

May 10 18:36:25 buildroot kern.warn kernel: wg_receive+0x16/0x25

May 10 18:36:25 buildroot kern.warn kernel: udp_queue_rcv_skb+0x254/0x324

May 10 18:36:25 buildroot kern.warn kernel: udp_unicast_rcv_skb.isra.12+0x68/0x7a

May 10 18:36:25 buildroot kern.warn kernel: __udp4_lib_rcv+0x413/0x88b

May 10 18:36:25 buildroot kern.warn kernel: udp_rcv+0x12/0x14

May 10 18:36:25 buildroot kern.warn kernel: ip_local_deliver_finish+0x82/0x1ff

May 10 18:36:25 buildroot kern.warn kernel: ip_local_deliver+0xc0/0xcb

May 10 18:36:25 buildroot kern.warn kernel: ? ip_sublist_rcv_finish+0x41/0x41

May 10 18:36:25 buildroot kern.warn kernel: ip_rcv_finish+0x24/0x2a

May 10 18:36:25 buildroot kern.warn kernel: ip_rcv+0xa1/0xaf

May 10 18:36:25 buildroot kern.warn kernel: ? ip_rcv_finish_core.isra.0+0x331/0x331

May 10 18:36:25 buildroot kern.warn kernel: __netif_receive_skb_one_core+0x3f/0x59

May 10 18:36:25 buildroot kern.warn kernel: __netif_receive_skb+0x16/0x4f

May 10 18:36:25 buildroot kern.warn kernel: netif_receive_skb_internal+0x26/0xaf

May 10 18:36:25 buildroot kern.warn kernel: netif_receive_skb+0x8/0xa

May 10 18:36:25 buildroot kern.warn kernel: rhine_napipoll+0x5ef/0x9c6

May 10 18:36:25 buildroot kern.warn kernel: net_rx_action+0x197/0x24d

May 10 18:36:25 buildroot kern.warn kernel: __do_softirq+0xd6/0x1ae

May 10 18:36:25 buildroot kern.warn kernel: run_ksoftirqd+0x21/0x24

May 10 18:36:25 buildroot kern.warn kernel: smpboot_thread_fn+0x137/0x1ea

May 10 18:36:25 buildroot kern.warn kernel: kthread+0xbe/0xea

May 10 18:36:25 buildroot kern.warn kernel: ? sort_range+0x18/0x18

May 10 18:36:25 buildroot kern.warn kernel: ? __kthread_create_on_node+0x13e/0x13e

May 10 18:36:25 buildroot kern.warn kernel: ret_from_fork+0x19/0x24

May 10 18:36:25 buildroot kern.warn kernel: ---[ end trace c200a14cd22c0ee1 ]---

May 10 18:36:25 buildroot kern.warn kernel: WARNING: CPU: 0 PID: 9 at kernel/workqueue.c:1442 __queue_work+0x1d4/0x2aa

May 10 18:36:25 buildroot kern.warn kernel: CPU: 0 PID: 9 Comm: ksoftirqd/0 Tainted: G W 4.19.41-banana #1

May 10 18:36:25 buildroot kern.warn kernel: EIP: __queue_work+0x1d4/0x2aa

May 10 18:36:25 buildroot kern.warn kernel: EAX: 00000000 EBX: cfb62044 ECX: 00000003 EDX: cfb62048