======================================
| [   15.623406][    C2] 1 lock held by ksoftirqd/2/27:
| [ 15.623583][ C2] #0: ffffffff8a1774c0 (rcu_callback){....}-{0:0}, at: rcu_do_batch (./include/linux/rcupdate.h:331 kernel/rcu/tree.c:2570) 
| [   15.623911][    C2]
| [   15.623911][    C2] stack backtrace:
[   15.624139][    C2] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   15.624141][    C2] Call Trace:
[   15.624143][    C2]  <TASK>
[ 15.624146][ C2] dump_stack_lvl (lib/dump_stack.c:123) 
[ 15.624153][ C2] print_usage_bug.part.0 (kernel/locking/lockdep.c:4048) 
[ 15.624159][ C2] mark_lock_irq (kernel/locking/lockdep.c:4013 kernel/locking/lockdep.c:4059 kernel/locking/lockdep.c:4270) 
[ 15.624164][ C2] ? __pfx_unwind_next_frame (arch/x86/kernel/unwind_orc.c:469) 
[ 15.624170][ C2] ? save_trace (kernel/locking/lockdep.c:595) 
[ 15.624174][ C2] mark_lock (kernel/locking/lockdep.c:4756) 
[ 15.624178][ C2] mark_usage (kernel/locking/lockdep.c:4645) 
[ 15.624181][ C2] __lock_acquire (kernel/locking/lockdep.c:5194) 
[ 15.624185][ C2] ? __lock_acquire (kernel/locking/lockdep.c:5240) 
[ 15.624189][ C2] lock_acquire.part.0 (kernel/locking/lockdep.c:473 kernel/locking/lockdep.c:5873) 
[ 15.624192][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 15.624197][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.624202][ C2] ? lock_acquire (./include/trace/events/lock.h:24 kernel/locking/lockdep.c:5834) 
[ 15.624205][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 15.624209][ C2] _raw_spin_lock (./include/linux/spinlock_api_smp.h:134 kernel/locking/spinlock.c:154) 
[ 15.624213][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 15.624215][ C2] simple_pin_fs (fs/libfs.c:1067) 
[ 15.624218][ C2] debugfs_remove (fs/debugfs/inode.c:805 fs/debugfs/inode.c:799) 
[ 15.624223][ C2] ref_tracker_dir_exit (lib/ref_tracker.c:412 lib/ref_tracker.c:196) 
[ 15.624227][ C2] ? __pfx_ref_tracker_free (lib/ref_tracker.c:254) 
[ 15.624230][ 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) 
[ 15.624236][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.624239][ C2] ? __pfx_ref_tracker_dir_exit (lib/ref_tracker.c:190) 
[ 15.624242][ C2] ? smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 15.624245][ C2] ? kthread (kernel/kthread.c:464) 
[ 15.624249][ C2] ? ret_from_fork (arch/x86/kernel/process.c:148) 
[ 15.624253][ C2] ? ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
[ 15.624257][ 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) 
[ 15.624261][ C2] ? __pfx_migrate_enable (kernel/sched/core.c:2402) 
[ 15.624267][ C2] __put_net (net/core/net_namespace.c:732) 
[ 15.624272][ C2] __sk_destruct (./include/net/net_namespace.h:288 ./include/net/net_namespace.h:390 net/core/sock.c:2376) 
[ 15.624276][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.624278][ C2] rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.624283][ C2] ? __pfx_rcu_do_batch (kernel/rcu/tree.c:2500) 
[ 15.624287][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.624291][ C2] ? note_gp_changes (kernel/rcu/tree.c:1326 (discriminator 1)) 
[ 15.624294][ C2] ? lockdep_hardirqs_on (kernel/locking/lockdep.c:4475) 
[ 15.624300][ C2] rcu_core (kernel/rcu/tree.c:2834) 
[ 15.624305][ C2] handle_softirqs (kernel/softirq.c:579) 
[ 15.624309][ C2] ? __pfx_run_ksoftirqd (kernel/softirq.c:961) 
[ 15.624313][ C2] run_ksoftirqd (kernel/softirq.c:436 kernel/softirq.c:969 kernel/softirq.c:960) 
[ 15.624316][ C2] smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 15.624319][ C2] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 15.624323][ C2] kthread (kernel/kthread.c:464) 
[ 15.624326][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 15.624328][ C2] ? ret_from_fork (arch/x86/kernel/process.c:147) 
[ 15.624331][ C2] ? __lock_release (kernel/locking/lockdep.c:5539) 
[ 15.624334][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.624338][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 15.624341][ C2] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 15.624344][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 15.624346][ C2] ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
| [   15.636377][    C2] RCU nest depth: 0, expected: 0
| [   15.636604][    C2] INFO: lockdep is turned off.
| [   15.636788][    C2] Preemption disabled at:
| [ 15.636790][ C2] handle_softirqs (kernel/softirq.c:553) 
[   15.637198][    C2] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   15.637200][    C2] Call Trace:
[   15.637202][    C2]  <TASK>
[ 15.637204][ C2] dump_stack_lvl (lib/dump_stack.c:123) 
[ 15.637212][ C2] __might_resched (kernel/sched/core.c:8796) 
[ 15.637220][ C2] down_write (./include/linux/kernel.h:73 kernel/locking/rwsem.c:1576) 
[ 15.637224][ C2] ? __pfx_down_write (kernel/locking/rwsem.c:1575) 
[ 15.637227][ C2] ? simple_recursive_removal (fs/libfs.c:614) 
[ 15.637233][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.637239][ 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) 
[ 15.637243][ C2] simple_recursive_removal (./include/linux/dcache.h:409 ./include/linux/dcache.h:424 ./include/linux/dcache.h:434 fs/libfs.c:617) 
[ 15.637246][ 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) 
[ 15.637249][ C2] ? __pfx_remove_one (fs/debugfs/inode.c:780) 
[ 15.637254][ C2] debugfs_remove (fs/debugfs/inode.c:806 fs/debugfs/inode.c:799) 
[ 15.637258][ C2] ref_tracker_dir_exit (lib/ref_tracker.c:412 lib/ref_tracker.c:196) 
[ 15.637262][ C2] ? __pfx_ref_tracker_free (lib/ref_tracker.c:254) 
[ 15.637265][ 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) 
[ 15.637271][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.637275][ C2] ? __pfx_ref_tracker_dir_exit (lib/ref_tracker.c:190) 
[ 15.637278][ C2] ? smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 15.637280][ C2] ? kthread (kernel/kthread.c:464) 
[ 15.637284][ C2] ? ret_from_fork (arch/x86/kernel/process.c:148) 
[ 15.637289][ C2] ? ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
[ 15.637294][ 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) 
[ 15.637298][ C2] ? __pfx_migrate_enable (kernel/sched/core.c:2402) 
[ 15.637304][ C2] __put_net (net/core/net_namespace.c:732) 
[ 15.637308][ C2] __sk_destruct (./include/net/net_namespace.h:288 ./include/net/net_namespace.h:390 net/core/sock.c:2376) 
[ 15.637312][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.637315][ C2] rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.637320][ C2] ? __pfx_rcu_do_batch (kernel/rcu/tree.c:2500) 
[ 15.637324][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.637327][ C2] ? note_gp_changes (kernel/rcu/tree.c:1326 (discriminator 1)) 
[ 15.637330][ C2] ? lockdep_hardirqs_on (kernel/locking/lockdep.c:4475) 
[ 15.637336][ C2] rcu_core (kernel/rcu/tree.c:2834) 
[ 15.637341][ C2] handle_softirqs (kernel/softirq.c:579) 
[ 15.637346][ C2] ? __pfx_run_ksoftirqd (kernel/softirq.c:961) 
[ 15.637350][ C2] run_ksoftirqd (kernel/softirq.c:436 kernel/softirq.c:969 kernel/softirq.c:960) 
[ 15.637353][ C2] smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 15.637356][ C2] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 15.637359][ C2] kthread (kernel/kthread.c:464) 
[ 15.637362][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 15.637364][ C2] ? ret_from_fork (arch/x86/kernel/process.c:147) 
[ 15.637367][ C2] ? __lock_release (kernel/locking/lockdep.c:5539) 
[ 15.637373][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.637376][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 15.637379][ C2] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 15.637382][ 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