gistfile1.txt

INFO: task xenwatch:108 blocked for more than 120 seconds.
      Tainted: G        W        4.15.0-20-generic #21-Ubuntu
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
xenwatch        D    0   108      2 0x80000000
Call Trace:
 __schedule+0x297/0x8b0
 schedule+0x2c/0x80
 xennet_remove+0xda/0x1c0
 ? wait_woken+0x80/0x80
 xenbus_dev_remove+0x54/0xa0
 device_release_driver_internal+0x15b/0x220
 device_release_driver+0x12/0x20
 bus_remove_device+0xec/0x160
 ? xenbus_otherend_changed+0x110/0x110
 device_del+0x13d/0x360
 ? xenbus_otherend_changed+0x110/0x110
 ? xenbus_otherend_changed+0x110/0x110
 device_unregister+0x1a/0x60
 xenbus_dev_changed+0xa3/0x1e0
 ? xenwatch_thread+0xcc/0x160
 frontend_changed+0x21/0x50
 xenwatch_thread+0xc4/0x160
 ? wait_woken+0x80/0x80
 kthread+0x121/0x140
 ? find_watch+0x40/0x40
 ? kthread_create_worker_on_cpu+0x70/0x70
 ret_from_fork+0x35/0x40

Possible fix:
xen-netfront: Fix hang on device removal
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c2d2e6738a209f0f9dffa2dc8e7292fc45360d61