Comment 7 for bug 1854968

And on an arm64 platform we have something similar:

15:55:45 DEBUG| [stdout] Number of CPUs: 4
15:55:45 DEBUG| [stdout] Number of CPUs Online: 4
15:55:45 DEBUG| [stdout]
15:55:45 DEBUG| [stdout] access STARTING
15:55:49 DEBUG| [stdout] [ 7016.776865] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:55:50 DEBUG| [stdout] access RETURNED 0
15:55:50 DEBUG| [stdout] access PASSED
15:55:50 DEBUG| [stdout] af-alg STARTING
15:55:50 DEBUG| [stdout] [ 7017.948549] cryptd: max_cpu_qlen set to 1000
15:55:55 DEBUG| [stdout] af-alg RETURNED 0
15:55:55 DEBUG| [stdout] af-alg PASSED
15:55:55 DEBUG| [stdout] affinity STARTING
15:55:59 DEBUG| [stdout] [ 7026.984742] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:56:00 DEBUG| [stdout] affinity RETURNED 0
15:56:00 DEBUG| [stdout] affinity PASSED
15:56:00 DEBUG| [stdout] aio STARTING
15:56:05 DEBUG| [stdout] aio RETURNED 0
15:56:05 DEBUG| [stdout] aio PASSED
15:56:05 DEBUG| [stdout] aiol STARTING
15:56:09 DEBUG| [stdout] [ 7037.068696] unregister_netdevice: waiting for eth0 to become free. Usage count = 1

...and a stack dump too. protocol family 5 is AF_APPLETALK and stress-ng does not use exercise this, so this is pretty weird and unexpected.

15:57:08 DEBUG| [stdout] [ 7096.221119] NET: Registered protocol family 5
15:57:10 DEBUG| [stdout] [ 7098.023954] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:57:20 DEBUG| [stdout] [ 7108.103839] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:57:30 DEBUG| [stdout] [ 7118.183729] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:57:41 DEBUG| [stdout] [ 7128.267622] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:57:51 DEBUG| [stdout] [ 7138.343507] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:58:01 DEBUG| [stdout] [ 7148.427381] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:58:11 DEBUG| [stdout] [ 7158.503282] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:58:21 DEBUG| [stdout] [ 7168.587157] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:58:31 DEBUG| [stdout] [ 7178.663042] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:58:41 DEBUG| [stdout] [ 7188.742924] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:58:51 DEBUG| [stdout] [ 7198.822826] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:59:01 DEBUG| [stdout] [ 7208.902688] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:59:11 DEBUG| [stdout] [ 7218.982579] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:59:21 DEBUG| [stdout] [ 7229.062465] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:59:31 DEBUG| [stdout] [ 7239.142348] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:59:42 DEBUG| [stdout] [ 7249.222274] unregister_netdevice: waiting for eth0 to become free. Usage count = 1
15:59:44 DEBUG| [stdout] [ 7251.334302] INFO: task modprobe:1184184 blocked for more than 120 seconds.
15:59:44 DEBUG| [stdout] [ 7251.335644] Tainted: G OE 5.4.0-7-generic #8-Ubuntu
15:59:44 DEBUG| [stdout] [ 7251.336889] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
15:59:44 DEBUG| [stdout] [ 7251.338455] modprobe D 0 1184184 1142782 0x00000028
15:59:44 DEBUG| [stdout] [ 7251.338461] Call trace:
15:59:44 DEBUG| [stdout] [ 7251.338472] __switch_to+0xe4/0x148
15:59:44 DEBUG| [stdout] [ 7251.338478] __schedule+0x2fc/0x7c0
15:59:44 DEBUG| [stdout] [ 7251.338489] schedule+0x3c/0xb8
15:59:44 DEBUG| [stdout] [ 7251.338501] rwsem_down_write_slowpath+0x2e8/0x5b0
15:59:44 DEBUG| [stdout] [ 7251.338512] down_write+0x70/0x80
15:59:44 DEBUG| [stdout] [ 7251.338525] register_netdevice_notifier+0x4c/0x208
15:59:44 DEBUG| [stdout] [ 7251.338548] atalk_init+0xa0/0x118 [appletalk]
15:59:44 DEBUG| [stdout] [ 7251.338570] do_one_initcall+0x50/0x220
15:59:44 DEBUG| [stdout] [ 7251.338575] do_init_module+0x5c/0x248
15:59:44 DEBUG| [stdout] [ 7251.338582] load_module+0xecc/0x1170
15:59:44 DEBUG| [stdout] [ 7251.338585] __do_sys_finit_module+0xac/0x110
15:59:44 DEBUG| [stdout] [ 7251.338587] __arm64_sys_finit_module+0x28/0x38
15:59:44 DEBUG| [stdout] [ 7251.338591] el0_svc_common.constprop.0+0xdc/0x1d8
15:59:44 DEBUG| [stdout] [ 7251.338593] el0_svc_handler+0x34/0xa0
15:59:44 DEBUG| [stdout] [ 7251.338595] el0_svc+0x10/0x14