======================================
| [   12.500496][    C2] 1 lock held by ksoftirqd/2/27:
| [ 12.500668][ C2] #0: ffffffff87f774c0 (rcu_callback){....}-{0:0}, at: rcu_do_batch (./include/linux/rcupdate.h:331 kernel/rcu/tree.c:2570) 
| [   12.500976][    C2]
| [   12.500976][    C2] stack backtrace:
[   12.501195][    C2] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   12.501197][    C2] Call Trace:
[   12.501198][    C2]  <TASK>
[ 12.501201][ C2] dump_stack_lvl (lib/dump_stack.c:123) 
[ 12.501207][ C2] print_usage_bug.part.0 (kernel/locking/lockdep.c:4048) 
[ 12.501213][ C2] mark_lock_irq (kernel/locking/lockdep.c:4013 kernel/locking/lockdep.c:4059 kernel/locking/lockdep.c:4270) 
[ 12.501218][ C2] ? __pfx_unwind_next_frame (arch/x86/kernel/unwind_orc.c:469) 
[ 12.501223][ C2] ? save_trace (kernel/locking/lockdep.c:595) 
[ 12.501227][ C2] mark_lock (kernel/locking/lockdep.c:4756) 
[ 12.501231][ C2] mark_usage (kernel/locking/lockdep.c:4645) 
[ 12.501234][ C2] __lock_acquire (kernel/locking/lockdep.c:5194) 
[ 12.501238][ C2] ? __lock_acquire (kernel/locking/lockdep.c:5240) 
[ 12.501242][ C2] lock_acquire.part.0 (kernel/locking/lockdep.c:473 kernel/locking/lockdep.c:5873) 
[ 12.501245][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 12.501250][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.501255][ C2] ? lock_acquire (./include/trace/events/lock.h:24 kernel/locking/lockdep.c:5834) 
[ 12.501258][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 12.501262][ C2] _raw_spin_lock (./include/linux/spinlock_api_smp.h:134 kernel/locking/spinlock.c:154) 
[ 12.501265][ C2] ? simple_pin_fs (fs/libfs.c:1067) 
[ 12.501268][ C2] simple_pin_fs (fs/libfs.c:1067) 
[ 12.501271][ C2] debugfs_remove (fs/debugfs/inode.c:805 fs/debugfs/inode.c:799) 
[ 12.501275][ C2] ref_tracker_dir_exit (lib/ref_tracker.c:411 lib/ref_tracker.c:195) 
[ 12.501280][ C2] ? __pfx_ref_tracker_free (lib/ref_tracker.c:253) 
[ 12.501283][ 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) 
[ 12.501288][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.501291][ C2] ? __pfx_ref_tracker_dir_exit (lib/ref_tracker.c:189) 
[ 12.501294][ C2] ? smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 12.501297][ C2] ? kthread (kernel/kthread.c:464) 
[ 12.501301][ C2] ? ret_from_fork (arch/x86/kernel/process.c:148) 
[ 12.501305][ C2] ? ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
[ 12.501309][ 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) 
[ 12.501313][ C2] ? __pfx_migrate_enable (kernel/sched/core.c:2402) 
[ 12.501319][ C2] __put_net (net/core/net_namespace.c:732) 
[ 12.501323][ C2] __sk_destruct (./include/net/net_namespace.h:288 ./include/net/net_namespace.h:390 net/core/sock.c:2376) 
[ 12.501327][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.501330][ C2] rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.501335][ C2] ? __pfx_rcu_do_batch (kernel/rcu/tree.c:2500) 
[ 12.501338][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.501341][ C2] ? note_gp_changes (kernel/rcu/tree.c:1326 (discriminator 1)) 
[ 12.501344][ C2] ? lockdep_hardirqs_on (kernel/locking/lockdep.c:4475) 
[ 12.501351][ C2] rcu_core (kernel/rcu/tree.c:2834) 
[ 12.501355][ C2] handle_softirqs (kernel/softirq.c:579) 
[ 12.501360][ C2] ? __pfx_run_ksoftirqd (kernel/softirq.c:961) 
[ 12.501364][ C2] run_ksoftirqd (kernel/softirq.c:436 kernel/softirq.c:969 kernel/softirq.c:960) 
[ 12.501367][ C2] smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 12.501370][ C2] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 12.501373][ C2] kthread (kernel/kthread.c:464) 
[ 12.501377][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 12.501379][ C2] ? ret_from_fork (arch/x86/kernel/process.c:147) 
[ 12.501382][ C2] ? __lock_release (kernel/locking/lockdep.c:5539) 
[ 12.501386][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.501389][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 12.501392][ C2] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 12.501395][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 12.501398][ C2] ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
| [   12.511940][    C2] RCU nest depth: 0, expected: 0
| [   12.512108][    C2] INFO: lockdep is turned off.
| [   12.512283][    C2] Preemption disabled at:
| [ 12.512285][ C2] handle_softirqs (kernel/softirq.c:553) 
[   12.512648][    C2] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[   12.512650][    C2] Call Trace:
[   12.512652][    C2]  <TASK>
[ 12.512654][ C2] dump_stack_lvl (lib/dump_stack.c:123) 
[ 12.512660][ C2] __might_resched (kernel/sched/core.c:8796) 
[ 12.512668][ C2] down_write (./include/linux/kernel.h:73 kernel/locking/rwsem.c:1576) 
[ 12.512671][ C2] ? __pfx_down_write (kernel/locking/rwsem.c:1575) 
[ 12.512674][ C2] ? simple_recursive_removal (fs/libfs.c:614) 
[ 12.512679][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.512684][ 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) 
[ 12.512688][ C2] simple_recursive_removal (./include/linux/dcache.h:409 ./include/linux/dcache.h:424 ./include/linux/dcache.h:434 fs/libfs.c:617) 
[ 12.512691][ 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) 
[ 12.512694][ C2] ? __pfx_remove_one (fs/debugfs/inode.c:780) 
[ 12.512699][ C2] debugfs_remove (fs/debugfs/inode.c:806 fs/debugfs/inode.c:799) 
[ 12.512702][ C2] ref_tracker_dir_exit (lib/ref_tracker.c:411 lib/ref_tracker.c:195) 
[ 12.512706][ C2] ? __pfx_ref_tracker_free (lib/ref_tracker.c:253) 
[ 12.512709][ 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) 
[ 12.512714][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.512717][ C2] ? __pfx_ref_tracker_dir_exit (lib/ref_tracker.c:189) 
[ 12.512720][ C2] ? smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 12.512723][ C2] ? kthread (kernel/kthread.c:464) 
[ 12.512726][ C2] ? ret_from_fork (arch/x86/kernel/process.c:148) 
[ 12.512731][ C2] ? ret_from_fork_asm (arch/x86/entry/entry_64.S:258) 
[ 12.512734][ 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) 
[ 12.512738][ C2] ? __pfx_migrate_enable (kernel/sched/core.c:2402) 
[ 12.512744][ C2] __put_net (net/core/net_namespace.c:732) 
[ 12.512747][ C2] __sk_destruct (./include/net/net_namespace.h:288 ./include/net/net_namespace.h:390 net/core/sock.c:2376) 
[ 12.512752][ C2] ? rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.512754][ C2] rcu_do_batch (kernel/rcu/tree.c:2576) 
[ 12.512759][ C2] ? __pfx_rcu_do_batch (kernel/rcu/tree.c:2500) 
[ 12.512763][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.512766][ C2] ? note_gp_changes (kernel/rcu/tree.c:1326 (discriminator 1)) 
[ 12.512769][ C2] ? lockdep_hardirqs_on (kernel/locking/lockdep.c:4475) 
[ 12.512775][ C2] rcu_core (kernel/rcu/tree.c:2834) 
[ 12.512780][ C2] handle_softirqs (kernel/softirq.c:579) 
[ 12.512784][ C2] ? __pfx_run_ksoftirqd (kernel/softirq.c:961) 
[ 12.512789][ C2] run_ksoftirqd (kernel/softirq.c:436 kernel/softirq.c:969 kernel/softirq.c:960) 
[ 12.512792][ C2] smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 12.512794][ C2] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 12.512798][ C2] kthread (kernel/kthread.c:464) 
[ 12.512801][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 12.512803][ C2] ? ret_from_fork (arch/x86/kernel/process.c:147) 
[ 12.512806][ C2] ? __lock_release (kernel/locking/lockdep.c:5539) 
[ 12.512811][ C2] ? rcu_is_watching (./include/linux/context_tracking.h:128 kernel/rcu/tree.c:745) 
[ 12.512814][ C2] ? __pfx_kthread (kernel/kthread.c:413) 
[ 12.512817][ C2] ret_from_fork (arch/x86/kernel/process.c:148) 
[ 12.512820][ 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