======================================
| [   15.132799][    C2] 1 lock held by ksoftirqd/2/27:
| [ 15.133037][ C2] #0: ffffffff8b9774c0 (rcu_callback){....}-{0:0}, at: rcu_do_batch (./include/linux/rcupdate.h:331 kernel/rcu/tree.c:2570) 
| [   15.133445][    C2]
| [   15.133445][    C2] stack backtrace:
[   15.133730][    C2] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   15.133734][    C2] Call Trace:
[   15.133737][    C2]  <TASK>
[ 15.133741][ C2] dump_stack_lvl (lib/dump_stack.c:123) 
[ 15.133753][ C2] print_usage_bug.part.0 (kernel/locking/lockdep.c:4048) 
[ 15.133764][ C2] mark_lock_irq (kernel/locking/lockdep.c:4013 kernel/locking/lockdep.c:4059 kernel/locking/lockdep.c:4270) 
[ 15.133771][ C2] ? __pfx_unwind_next_frame (arch/x86/kernel/unwind_orc.c:469) 
[ 15.133781][ C2] ? save_trace (kernel/locking/lockdep.c:595) 
[ 15.133787][ C2] mark_lock (kernel/locking/lockdep.c:4756) 
[ 15.133794][ C2] mark_usage (kernel/locking/lockdep.c:4645) 
[ 15.133800][ C2] __lock_acquire (kernel/locking/lockdep.c:5194) 
[ 15.133805][ C2] ? __lock_acquire (kernel/locking/lockdep.c:5240) 
[ 15.133812][ C2] lock_acquire.part.0 (kernel/locking/lockdep.c:473 kernel/locking/lockdep.c:5873) 
[ 15.133817][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 15.133825][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.133834][ C2] ? lock_acquire (./include/trace/events/lock.h:24 kernel/locking/lockdep.c:5834) 
[ 15.133837][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 15.133841][ C2] _raw_spin_lock (./include/linux/spinlock_api_smp.h:134 kernel/locking/spinlock.c:154) 
[ 15.133846][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 15.133848][ C2] simple_pin_fs (fs/libfs.c:1067) 
[ 15.133852][ C2] debugfs_remove (fs/debugfs/inode.c:805 fs/debugfs/inode.c:799) 
[ 15.133857][ C2] ref_tracker_dir_exit (lib/ref_tracker.c:412 lib/ref_tracker.c:196) 
[ 15.133864][ C2] ? __pfx_ref_tracker_free (lib/ref_tracker.c:254) 
[ 15.133867][ 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) 
[ 15.133873][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.133877][ C2] ? __pfx_ref_tracker_dir_exit (lib/ref_tracker.c:190) 
[ 15.133880][ C2] ? smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 15.133883][ C2] ? kthread (kernel/kthread.c:464) 
[ 15.133888][ C2] ? ret_from_fork (arch/x86/kernel/process.c:148) 
[ 15.133894][ C2] ? ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
[ 15.133899][ 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) 
[ 15.133904][ C2] ? __pfx_migrate_enable (kernel/sched/core.c:2402) 
[ 15.133910][ C2] __put_net (net/core/net_namespace.c:732) 
[ 15.133915][ C2] __sk_destruct (./include/net/net_namespace.h:288 ./include/net/net_namespace.h:390 net/core/sock.c:2376) 
[ 15.133922][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.133926][ C2] rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.133932][ C2] ? __schedule (kernel/sched/core.c:6658) 
[ 15.133942][ C2] ? __pfx_rcu_do_batch (kernel/rcu/tree.c:2500) 
[ 15.133948][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.133953][ C2] ? note_gp_changes (kernel/rcu/tree.c:1326 (discriminator 1)) 
[ 15.133958][ C2] ? lockdep_hardirqs_on (kernel/locking/lockdep.c:4475) 
[ 15.133967][ C2] rcu_core (kernel/rcu/tree.c:2834) 
[ 15.133975][ C2] handle_softirqs (kernel/softirq.c:579) 
[ 15.133985][ C2] ? __pfx_run_ksoftirqd (kernel/softirq.c:961) 
[ 15.133992][ C2] run_ksoftirqd (kernel/softirq.c:436 kernel/softirq.c:969 kernel/softirq.c:960) 
[ 15.133997][ C2] smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 15.134002][ C2] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 15.134005][ C2] kthread (kernel/kthread.c:464) 
[ 15.134009][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 15.134011][ C2] ? ret_from_fork (arch/x86/kernel/process.c:147) 
[ 15.134014][ C2] ? __lock_release (kernel/locking/lockdep.c:5539) 
[ 15.134018][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.134022][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 15.134025][ C2] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 15.134029][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 15.134032][ C2] ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
| [   15.148657][    C2] RCU nest depth: 0, expected: 0
| [   15.148908][    C2] INFO: lockdep is turned off.
| [   15.149100][    C2] Preemption disabled at:
| [ 15.149102][ C2] handle_softirqs (kernel/softirq.c:553) 
[   15.149520][    C2] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   15.149522][    C2] Call Trace:
[   15.149524][    C2]  <TASK>
[ 15.149528][ C2] dump_stack_lvl (lib/dump_stack.c:123) 
[ 15.149538][ C2] __might_resched (kernel/sched/core.c:8796) 
[ 15.149547][ C2] down_write (./include/linux/kernel.h:73 kernel/locking/rwsem.c:1576) 
[ 15.149553][ C2] ? __pfx_down_write (kernel/locking/rwsem.c:1575) 
[ 15.149556][ C2] ? simple_recursive_removal (fs/libfs.c:614) 
[ 15.149563][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.149571][ 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) 
[ 15.149575][ C2] simple_recursive_removal (./include/linux/dcache.h:409 ./include/linux/dcache.h:424 ./include/linux/dcache.h:434 fs/libfs.c:617) 
[ 15.149579][ 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) 
[ 15.149581][ C2] ? __pfx_remove_one (fs/debugfs/inode.c:780) 
[ 15.149589][ C2] debugfs_remove (fs/debugfs/inode.c:806 fs/debugfs/inode.c:799) 
[ 15.149594][ C2] ref_tracker_dir_exit (lib/ref_tracker.c:412 lib/ref_tracker.c:196) 
[ 15.149601][ C2] ? __pfx_ref_tracker_free (lib/ref_tracker.c:254) 
[ 15.149605][ 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) 
[ 15.149613][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.149620][ C2] ? __pfx_ref_tracker_dir_exit (lib/ref_tracker.c:190) 
[ 15.149624][ C2] ? smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 15.149629][ C2] ? kthread (kernel/kthread.c:464) 
[ 15.149633][ C2] ? ret_from_fork (arch/x86/kernel/process.c:148) 
[ 15.149640][ C2] ? ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
[ 15.149644][ 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) 
[ 15.149649][ C2] ? __pfx_migrate_enable (kernel/sched/core.c:2402) 
[ 15.149655][ C2] __put_net (net/core/net_namespace.c:732) 
[ 15.149660][ C2] __sk_destruct (./include/net/net_namespace.h:288 ./include/net/net_namespace.h:390 net/core/sock.c:2376) 
[ 15.149665][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.149668][ C2] rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 15.149671][ C2] ? __schedule (kernel/sched/core.c:6658) 
[ 15.149679][ C2] ? __pfx_rcu_do_batch (kernel/rcu/tree.c:2500) 
[ 15.149683][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.149687][ C2] ? note_gp_changes (kernel/rcu/tree.c:1326 (discriminator 1)) 
[ 15.149690][ C2] ? lockdep_hardirqs_on (kernel/locking/lockdep.c:4475) 
[ 15.149697][ C2] rcu_core (kernel/rcu/tree.c:2834) 
[ 15.149703][ C2] handle_softirqs (kernel/softirq.c:579) 
[ 15.149708][ C2] ? __pfx_run_ksoftirqd (kernel/softirq.c:961) 
[ 15.149712][ C2] run_ksoftirqd (kernel/softirq.c:436 kernel/softirq.c:969 kernel/softirq.c:960) 
[ 15.149715][ C2] smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 15.149718][ C2] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 15.149721][ C2] kthread (kernel/kthread.c:464) 
[ 15.149724][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 15.149727][ C2] ? ret_from_fork (arch/x86/kernel/process.c:147) 
[ 15.149730][ C2] ? __lock_release (kernel/locking/lockdep.c:5539) 
[ 15.149735][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 15.149738][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 15.149742][ C2] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 15.149745][ 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