BUG: spinlock recursion on CPU#0, kworker/u9:4/7741
 lock: 0xffff80001a783080, .magic: dead4ead, .owner: kworker/u9:4/7741, .owner_cpu: 1
CPU: 0 PID: 7741 Comm: kworker/u9:4 Not tainted 4.15.0 #3
Hardware name: linux,dummy-virt (DT)
Workqueue: events_unbound call_usermodehelper_exec_work
Call trace:
 dump_backtrace+0x0/0x330 arch/arm64/kernel/time.c:52
 show_stack+0x20/0x30 arch/arm64/kernel/traps.c:151
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xd0/0x120 lib/dump_stack.c:53
 spin_dump+0x150/0x1f0 kernel/locking/spinlock_debug.c:67
 spin_bug kernel/locking/spinlock_debug.c:75 [inline]
 debug_spin_lock_before kernel/locking/spinlock_debug.c:84 [inline]
 do_raw_spin_lock+0x1e4/0x250 kernel/locking/spinlock_debug.c:112
 __raw_spin_lock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_lock+0x44/0x50 kernel/locking/spinlock.c:144
 rq_lock kernel/sched/sched.h:1766 [inline]
 ttwu_queue kernel/sched/core.c:1863 [inline]
 try_to_wake_up+0x6c0/0xa58 kernel/sched/core.c:2078
 default_wake_function+0x30/0x50 kernel/sched/core.c:3628
 __wake_up_common+0x128/0x470 kernel/sched/wait.c:97
 __wake_up_locked+0x18/0x20 kernel/sched/wait.c:158
 complete+0x68/0x90 kernel/sched/completion.c:39
 umh_complete+0x40/0xa8 kernel/umh.c:55
 call_usermodehelper_exec_sync kernel/umh.c:152 [inline]
 call_usermodehelper_exec_work+0x160/0x240 kernel/umh.c:175
 process_one_work+0x590/0xe90 kernel/workqueue.c:2113
 worker_thread+0x3b0/0xd30 kernel/workqueue.c:2247
 kthread+0x2a4/0x378 kernel/kthread.c:238
 ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:994