Marek found this bug while testing:
BUG: spinlock lockup on CPU#0, bat_events/516, c0200280 Call Trace: [<80048f34>] dump_stack+0x8/0x34 [<80154700>] _raw_spin_lock+0x104/0x12c [<80223350>] _spin_lock+0x64/0x80 [<c01f4420>] purge_orig+0x30/0x2f4 [batman_adv] [<80078098>] run_workqueue+0x170/0x270 [<80078e48>] worker_thread+0xac/0xd4 [<8007c918>] kthread+0x58/0xa0 [<800455d4>] kernel_thread_helper+0x10/0x18
this seems to be present in r1397. It rarely occurs ~1 second after loading the module.
Seems the spinlock is held elsewhere.
Another similar occurence has been found here:
BUG: spinlock lockup on CPU#0, bat_events/1346, c01ea280 Call Trace: [<80048f34>] dump_stack+0x8/0x34 [<80154d20>] _raw_spin_lock+0x104/0x12c [<80223970>] _spin_lock+0x64/0x80 [<c01e1fa0>] purge_vis_packets+0x138/0x83c [batman_adv]