======================================
| [ 56.188046][ C2] common_startup_64 (arch/x86/kernel/head_64.S:421) 
| [   56.188193][    C2]
| [   56.188262][    C2]
| [   56.188262][    C2] stack backtrace:
[   56.188658][    C2] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   56.188991][    C2] Call Trace:
[   56.189107][    C2]  <IRQ>
[ 56.189179][ C2] dump_stack_lvl (lib/dump_stack.c:117) 
[ 56.189330][ C2] print_irq_inversion_bug.part.0 (kernel/locking/lockdep.c:4024) 
[ 56.189588][ C2] ? common_startup_64 (arch/x86/kernel/head_64.S:421) 
[ 56.189730][ C2] ? __pfx_print_irq_inversion_bug.part.0 (kernel/locking/lockdep.c:4024) 
[ 56.189901][ C2] ? __pfx_usage_skip (kernel/locking/lockdep.c:2264) 
[ 56.190037][ C2] ? __pfx_usage_match (kernel/locking/lockdep.c:2256) 
[ 56.190258][ C2] ? arch_stack_walk (arch/x86/kernel/stacktrace.c:24) 
[ 56.190401][ C2] mark_lock_irq (kernel/locking/lockdep.c:4244) 
[ 56.190542][ C2] ? __pfx_mark_lock_irq (kernel/locking/lockdep.c:4207) 
[ 56.190679][ C2] ? stack_trace_save (kernel/stacktrace.c:123) 
[ 56.190924][ C2] ? add_chain_cache (kernel/locking/lockdep.c:3730) 
[ 56.191068][ C2] ? save_trace (kernel/locking/lockdep.c:586) 
[ 56.191210][ C2] mark_lock (kernel/locking/lockdep.c:4678) 
[ 56.191316][ C2] mark_usage (kernel/locking/lockdep.c:4567) 
[ 56.191421][ C2] __lock_acquire (kernel/locking/lockdep.c:5091) 
[ 56.191565][ C2] ? __lock_acquire (kernel/locking/lockdep.c:5137) 
[ 56.191708][ C2] ? __pfx_br_forward_delay_timer_expired (net/bridge/br_stp_timer.c:80) 
[ 56.191879][ C2] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5756) 
[ 56.192021][ C2] ? br_forward_delay_timer_expired (net/bridge/br_stp_timer.c:87) 
[ 56.192198][ C2] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 56.192336][ C2] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 56.192482][ C2] ? br_forward_delay_timer_expired (net/bridge/br_stp_timer.c:87) 
[ 56.192654][ C2] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 56.192884][ C2] ? br_forward_delay_timer_expired (net/bridge/br_stp_timer.c:87) 
[ 56.193070][ C2] _raw_spin_lock (./include/linux/spinlock_api_smp.h:134 kernel/locking/spinlock.c:154) 
[ 56.193206][ C2] ? br_forward_delay_timer_expired (net/bridge/br_stp_timer.c:87) 
[ 56.193381][ C2] br_forward_delay_timer_expired (net/bridge/br_stp_timer.c:87) 
[ 56.193631][ C2] ? __pfx_br_forward_delay_timer_expired (net/bridge/br_stp_timer.c:80) 
[ 56.193890][ C2] call_timer_fn (kernel/time/timer.c:1793) 
[ 56.194055][ C2] ? call_timer_fn (./include/linux/lockdep.h:31 kernel/time/timer.c:1783) 
[ 56.194320][ C2] ? call_timer_fn (./include/linux/lockdep.h:31 kernel/time/timer.c:1783) 
[ 56.194499][ C2] ? __pfx_call_timer_fn (kernel/time/timer.c:1770) 
[ 56.194661][ C2] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 56.194787][ C2] __run_timers (kernel/time/timer.c:1845 kernel/time/timer.c:2418) 
[ 56.194949][ C2] ? __pfx_br_forward_delay_timer_expired (net/bridge/br_stp_timer.c:80) 
[ 56.195154][ C2] ? __pfx___run_timers (kernel/time/timer.c:2389) 
[ 56.195319][ C2] ? __lock_release (kernel/locking/lockdep.c:5430) 
[ 56.195486][ C2] ? do_raw_spin_lock (./arch/x86/include/asm/atomic.h:115 ./include/linux/atomic/atomic-arch-fallback.h:2170 ./include/linux/atomic/atomic-instrumented.h:1302 ./include/asm-generic/qspinlock.h:111 kernel/locking/spinlock_debug.c:116) 
[ 56.195652][ C2] ? __pfx_do_raw_spin_lock (kernel/locking/spinlock_debug.c:114) 
[ 56.195907][ C2] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 56.196071][ C2] ? timer_expire_remote (kernel/time/timer.c:2429 kernel/time/timer.c:2422 kernel/time/timer.c:2181) 
[ 56.196236][ C2] timer_expire_remote (kernel/time/timer.c:2430 kernel/time/timer.c:2422 kernel/time/timer.c:2181) 
[ 56.196398][ C2] tmigr_handle_remote_cpu (./arch/x86/include/asm/irqflags.h:26 ./arch/x86/include/asm/irqflags.h:67 ./arch/x86/include/asm/irqflags.h:127 kernel/time/timer_migration.c:925) 
[ 56.196650][ C2] ? __pfx_tmigr_handle_remote_cpu (kernel/time/timer_migration.c:869) 
[ 56.196863][ C2] tmigr_handle_remote_up (kernel/time/timer_migration.c:1003) 
[ 56.197029][ C2] tmigr_handle_remote (kernel/time/timer_migration.c:488 kernel/time/timer_migration.c:1061) 
[ 56.197189][ C2] ? __pfx_tmigr_handle_remote (kernel/time/timer_migration.c:1026) 
[ 56.197437][ C2] __do_softirq (kernel/softirq.c:554) 
[ 56.197603][ C2] irq_exit_rcu (kernel/softirq.c:428 kernel/softirq.c:633 kernel/softirq.c:645) 
[ 56.197725][ C2] sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1043 arch/x86/kernel/apic/apic.c:1043) 
[   56.197893][    C2]  </IRQ>
[   56.197975][    C2]  <TASK>
[ 56.198066][ C2] asm_sysvec_apic_timer_interrupt (./arch/x86/include/asm/idtentry.h:702) 
[ 56.198350][ C2] RIP: 0010:default_idle (./arch/x86/include/asm/irqflags.h:37 ./arch/x86/include/asm/irqflags.h:72 arch/x86/kernel/process.c:743) 
[ 56.198517][ C2] Code: 4c 01 c7 4c 29 c2 e9 72 ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d b3 f7 2d 00 fb f4 <fa> c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90
All code
========
   0:	4c 01 c7             	add    %r8,%rdi
   3:	4c 29 c2             	sub    %r8,%rdx
   6:	e9 72 ff ff ff       	jmp    0xffffffffffffff7d
   b:	90                   	nop
   c:	90                   	nop
   d:	90                   	nop
   e:	90                   	nop
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	90                   	nop
  16:	90                   	nop
  17:	90                   	nop
  18:	90                   	nop
  19:	90                   	nop
  1a:	90                   	nop
  1b:	f3 0f 1e fa          	endbr64
  1f:	66 90                	xchg   %ax,%ax
  21:	0f 00 2d b3 f7 2d 00 	verw   0x2df7b3(%rip)        # 0x2df7db
  28:	fb                   	sti
  29:	f4                   	hlt
  2a:*	fa                   	cli		<-- trapping instruction
  2b:	c3                   	ret
  2c:	cc                   	int3
  2d:	cc                   	int3
  2e:	cc                   	int3
  2f:	cc                   	int3
  30:	66 66 2e 0f 1f 84 00 	data16 cs nopw 0x0(%rax,%rax,1)
  37:	00 00 00 00 
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	90                   	nop
  3f:	90                   	nop

Code starting with the faulting instruction
===========================================
   0:	fa                   	cli
   1:	c3                   	ret
   2:	cc                   	int3
   3:	cc                   	int3
   4:	cc                   	int3
   5:	cc                   	int3
   6:	66 66 2e 0f 1f 84 00 	data16 cs nopw 0x0(%rax,%rax,1)
   d:	00 00 00 00 
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	90                   	nop
[   56.199179][    C2] RSP: 0018:ffffc9000015fdf8 EFLAGS: 00000246
[   56.199389][    C2] RAX: 000000000016caf5 RBX: 1ffff9200002bfc1 RCX: ffffffffb2f822c5
[   56.199630][    C2] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffb08aa4a4
[   56.199949][    C2] RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed1006c2709c
[   56.200188][    C2] R10: ffff8880361384e3 R11: ffff88803613dc40 R12: 0000000000000000
[   56.200504][    C2] R13: ffff888001b845c0 R14: dffffc0000000000 R15: 0000000000000000
[ 56.200740][ C2] ? ct_kernel_exit.constprop.0 (kernel/context_tracking.c:147) 
[ 56.200904][ C2] ? cpuidle_idle_call (kernel/sched/idle.c:192) 
[ 56.201065][ C2] default_idle_call (./include/linux/cpuidle.h:143 kernel/sched/idle.c:118) 
[ 56.201299][ C2] cpuidle_idle_call (kernel/sched/idle.c:192) 
[ 56.201460][ C2] ? __pfx_cpuidle_idle_call (kernel/sched/idle.c:168) 
[ 56.201621][ C2] ? tsc_verify_tsc_adjust (arch/x86/kernel/tsc_sync.c:59) 
[ 56.201780][ C2] do_idle (kernel/sched/idle.c:332) 
[ 56.201901][ C2] cpu_startup_entry (kernel/sched/idle.c:429 (discriminator 1)) 
[ 56.202137][ C2] start_secondary (arch/x86/kernel/smpboot.c:201 arch/x86/kernel/smpboot.c:281) 
[ 56.202307][ C2] ? __pfx_start_secondary (arch/x86/kernel/smpboot.c:231) 


Finger prints:
common_startup_64:dump_stack_lvl:mark_lock_irq:mark_lock