======================================
| [   12.946675][    C2] 1 lock held by ksoftirqd/2/27:
| [ 12.946876][ C2] #0: ffffffff985774c0 (rcu_callback){....}-{0:0}, at: rcu_do_batch (./include/linux/rcupdate.h:331 kernel/rcu/tree.c:2570) 
| [   12.947235][    C2]
| [   12.947235][    C2] stack backtrace:
[   12.947485][    C2] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   12.947487][    C2] Call Trace:
[   12.947489][    C2]  <TASK>
[ 12.947492][ C2] dump_stack_lvl (lib/dump_stack.c:123) 
[ 12.947497][ C2] print_usage_bug.part.0 (kernel/locking/lockdep.c:4048) 
[ 12.947502][ C2] mark_lock_irq (kernel/locking/lockdep.c:4013 kernel/locking/lockdep.c:4059 kernel/locking/lockdep.c:4270) 
[ 12.947506][ C2] ? __pfx_unwind_next_frame (arch/x86/kernel/unwind_orc.c:469) 
[ 12.947513][ C2] ? save_trace (kernel/locking/lockdep.c:595) 
[ 12.947517][ C2] mark_lock (kernel/locking/lockdep.c:4756) 
[ 12.947521][ C2] mark_usage (kernel/locking/lockdep.c:4645) 
[ 12.947524][ C2] __lock_acquire (kernel/locking/lockdep.c:5194) 
[ 12.947527][ C2] ? __lock_acquire (kernel/locking/lockdep.c:5240) 
[ 12.947532][ C2] lock_acquire.part.0 (kernel/locking/lockdep.c:473 kernel/locking/lockdep.c:5873) 
[ 12.947535][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 12.947538][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.947544][ C2] ? lock_acquire (./include/trace/events/lock.h:24 kernel/locking/lockdep.c:5834) 
[ 12.947547][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 12.947550][ C2] _raw_spin_lock (./include/linux/spinlock_api_smp.h:134 kernel/locking/spinlock.c:154) 
[ 12.947553][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 12.947556][ C2] simple_pin_fs (fs/libfs.c:1067) 
[ 12.947559][ C2] debugfs_remove (fs/debugfs/inode.c:805 fs/debugfs/inode.c:799) 
[ 12.947562][ C2] ref_tracker_dir_exit (lib/ref_tracker.c:412 lib/ref_tracker.c:196) 
[ 12.947567][ C2] ? __pfx_ref_tracker_free (lib/ref_tracker.c:254) 
[ 12.947570][ C2] ? __sk_destruct (./include/linux/instrumented.h:96 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 ./include/net/net_namespace.h:287 ./include/net/net_namespace.h:390 net/core/sock.c:2376) 
[ 12.947575][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.947578][ C2] ? __pfx_ref_tracker_dir_exit (lib/ref_tracker.c:190) 
[ 12.947581][ C2] ? smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 12.947584][ C2] ? kthread (kernel/kthread.c:464) 
[ 12.947587][ C2] ? ret_from_fork (arch/x86/kernel/process.c:148) 
[ 12.947590][ C2] ? ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
[ 12.947592][ C2] ? migrate_enable (./arch/x86/include/asm/preempt.h:104 ./include/linux/preempt.h:481 ./include/linux/preempt.h:481 kernel/sched/core.c:2427) 
[ 12.947597][ C2] ? __pfx_migrate_enable (kernel/sched/core.c:2402) 
[ 12.947603][ C2] __put_net (net/core/net_namespace.c:732) 
[ 12.947606][ C2] __sk_destruct (./include/net/net_namespace.h:288 ./include/net/net_namespace.h:390 net/core/sock.c:2376) 
[ 12.947611][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.947613][ C2] rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.947616][ C2] ? __lock_release (kernel/locking/lockdep.c:5539) 
[ 12.947621][ C2] ? __pfx_rcu_do_batch (kernel/rcu/tree.c:2500) 
[ 12.947624][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.947628][ C2] ? note_gp_changes (kernel/rcu/tree.c:1326 (discriminator 1)) 
[ 12.947631][ C2] ? lockdep_hardirqs_on (kernel/locking/lockdep.c:4475) 
[ 12.947637][ C2] rcu_core (kernel/rcu/tree.c:2834) 
[ 12.947642][ C2] handle_softirqs (kernel/softirq.c:579) 
[ 12.947646][ C2] ? __pfx_run_ksoftirqd (kernel/softirq.c:961) 
[ 12.947650][ C2] run_ksoftirqd (kernel/softirq.c:436 kernel/softirq.c:969 kernel/softirq.c:960) 
[ 12.947653][ C2] smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 12.947657][ C2] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 12.947660][ C2] kthread (kernel/kthread.c:464) 
[ 12.947663][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 12.947665][ C2] ? ret_from_fork (arch/x86/kernel/process.c:147) 
[ 12.947668][ C2] ? __lock_release (kernel/locking/lockdep.c:5539) 
[ 12.947672][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.947675][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 12.947678][ C2] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 12.947681][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 12.947684][ C2] ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
| [   12.959982][    C2] RCU nest depth: 0, expected: 0
| [   12.960191][    C2] INFO: lockdep is turned off.
| [   12.960387][    C2] Preemption disabled at:
| [ 12.960389][ C2] handle_softirqs (kernel/softirq.c:553) 
[   12.960792][    C2] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   12.960794][    C2] Call Trace:
[   12.960796][    C2]  <TASK>
[ 12.960798][ C2] dump_stack_lvl (lib/dump_stack.c:123) 
[ 12.960804][ C2] __might_resched (kernel/sched/core.c:8796) 
[ 12.960811][ C2] down_write (./include/linux/kernel.h:73 kernel/locking/rwsem.c:1576) 
[ 12.960815][ C2] ? __pfx_down_write (kernel/locking/rwsem.c:1575) 
[ 12.960818][ C2] ? simple_recursive_removal (fs/libfs.c:614) 
[ 12.960823][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.960829][ C2] ? do_raw_spin_unlock (./arch/x86/include/asm/atomic.h:23 ./include/linux/atomic/atomic-arch-fallback.h:457 ./include/linux/atomic/atomic-instrumented.h:33 ./include/asm-generic/qspinlock.h:57 kernel/locking/spinlock_debug.c:101 kernel/locking/spinlock_debug.c:141) 
[ 12.960832][ C2] simple_recursive_removal (./include/linux/dcache.h:409 ./include/linux/dcache.h:424 ./include/linux/dcache.h:434 fs/libfs.c:617) 
[ 12.960836][ C2] ? do_raw_spin_unlock (./arch/x86/include/asm/atomic.h:23 ./include/linux/atomic/atomic-arch-fallback.h:457 ./include/linux/atomic/atomic-instrumented.h:33 ./include/asm-generic/qspinlock.h:57 kernel/locking/spinlock_debug.c:101 kernel/locking/spinlock_debug.c:141) 
[ 12.960838][ C2] ? __pfx_remove_one (fs/debugfs/inode.c:780) 
[ 12.960844][ C2] debugfs_remove (fs/debugfs/inode.c:806 fs/debugfs/inode.c:799) 
[ 12.960847][ C2] ref_tracker_dir_exit (lib/ref_tracker.c:412 lib/ref_tracker.c:196) 
[ 12.960851][ C2] ? __pfx_ref_tracker_free (lib/ref_tracker.c:254) 
[ 12.960854][ C2] ? __sk_destruct (./include/linux/instrumented.h:96 ./include/linux/atomic/atomic-instrumented.h:400 ./include/linux/refcount.h:389 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 ./include/net/net_namespace.h:287 ./include/net/net_namespace.h:390 net/core/sock.c:2376) 
[ 12.960858][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.960861][ C2] ? __pfx_ref_tracker_dir_exit (lib/ref_tracker.c:190) 
[ 12.960864][ C2] ? smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 12.960866][ C2] ? kthread (kernel/kthread.c:464) 
[ 12.960869][ C2] ? ret_from_fork (arch/x86/kernel/process.c:148) 
[ 12.960873][ C2] ? ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
[ 12.960876][ C2] ? migrate_enable (./arch/x86/include/asm/preempt.h:104 ./include/linux/preempt.h:481 ./include/linux/preempt.h:481 kernel/sched/core.c:2427) 
[ 12.960880][ C2] ? __pfx_migrate_enable (kernel/sched/core.c:2402) 
[ 12.960886][ C2] __put_net (net/core/net_namespace.c:732) 
[ 12.960890][ C2] __sk_destruct (./include/net/net_namespace.h:288 ./include/net/net_namespace.h:390 net/core/sock.c:2376) 
[ 12.960894][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.960896][ C2] rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.960900][ C2] ? __lock_release (kernel/locking/lockdep.c:5539) 
[ 12.960905][ C2] ? __pfx_rcu_do_batch (kernel/rcu/tree.c:2500) 
[ 12.960909][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.960912][ C2] ? note_gp_changes (kernel/rcu/tree.c:1326 (discriminator 1)) 
[ 12.960915][ C2] ? lockdep_hardirqs_on (kernel/locking/lockdep.c:4475) 
[ 12.960921][ C2] rcu_core (kernel/rcu/tree.c:2834) 
[ 12.960926][ C2] handle_softirqs (kernel/softirq.c:579) 
[ 12.960930][ C2] ? __pfx_run_ksoftirqd (kernel/softirq.c:961) 
[ 12.960934][ C2] run_ksoftirqd (kernel/softirq.c:436 kernel/softirq.c:969 kernel/softirq.c:960) 
[ 12.960937][ C2] smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 12.960940][ C2] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 12.960943][ C2] kthread (kernel/kthread.c:464) 
[ 12.960946][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 12.960949][ C2] ? ret_from_fork (arch/x86/kernel/process.c:147) 
[ 12.960952][ C2] ? __lock_release (kernel/locking/lockdep.c:5539) 
[ 12.960955][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.960959][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 12.960962][ C2] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 12.960965][ C2] ? __pfx_kthread (kernel/kthread.c:413) 


Finger prints:
handle_softirqs:dump_stack_lvl:__might_resched:down_write:simple_recursive_removal
mark_lock_irq:mark_lock:mark_usage:__lock_acquire:_raw_spin_lock