Comment 3 for bug 1574814

The traceback isn't always the same - here it was stuck in mod_timer():

[ 180.912269] NMI watchdog: BUG: soft lockup - CPU#9 stuck for 22s! [swapper/9:0]
[ 180.912293] Modules linked in: hid_generic(E) usbhid(E) hid(E) usb_storage(E) mdio_thunder(E) nicvf(E) ast(E) i2c_algo_bit(E) drm_kms_helper(E) syscopyarea(E) sysfillrect(E) sysimgblt(E) fb_sys_fops(E) ttm(E) drm(E) nicpf(E) thunder_bgx(E) mdio_cavium(E)
[ 180.912294]
[ 180.912298] CPU: 9 PID: 0 Comm: swapper/9 Tainted: G E 4.4.0-21-generic #37-Ubuntu
[ 180.912299] Hardware name: Cavium ThunderX CN88XX board (DT)
[ 180.912302] task: ffff801f6c9d0000 ti: ffff801f6c9cc000 task.ti: ffff801f6c9cc000
[ 180.912308] PC is at _raw_spin_unlock_irqrestore+0x2c/0x38
[ 180.912312] LR is at mod_timer+0x12c/0x270
[ 180.912314] pc : [<ffff8000008f5dc4>] lr : [<ffff800000131d2c>] pstate: 60400145
[ 180.912315] sp : ffff801f6c9cfba0
[ 180.912318] x29: ffff801f6c9cfba0 x28: ffff801f662982d8
[ 180.912320] x27: ffff801f6c9cfd00 x26: ffff801f7b369bb8
[ 180.912323] x25: ffff800000d69b80 x24: 0000000000000000
[ 180.912325] x23: ffff801f7b369b80 x22: ffff800000d8a000
[ 180.912328] x21: ffff801f7b369b80 x20: ffff801f7b369b80
[ 180.912330] x19: 0000000000000140 x18: 0000000000000069
[ 180.912332] x17: 0000000000468078 x16: ffff8000000c5b98
[ 180.912335] x15: 0000ffff7b779000 x14: 0000000000000008
[ 180.912337] x13: 0000000000000000 x12: 003d090000000000
[ 180.912340] x11: 00000000003d0900 x10: ffff80000090f200
[ 180.912342] x9 : 00003d0900000000 x8 : 000000000000000d
[ 180.912344] x7 : ffff801f7b3b4008 x6 : 0000000000000000
[ 180.912347] x5 : 0000000000000000 x4 : 0000000000000001
[ 180.912349] x3 : ffff801f6c9d0000 x2 : 00000000ffff8afb
[ 180.912351] x1 : 0000000000000140 x0 : 000000000000927c
[ 180.912352]