======================================
| xx__-> echo $?
| 0
| xx__-> [   56.252678][    C1] BUG: spinlock bad magic on CPU#1, ip/601
| [ 56.252973][ C1] lock: noop_qdisc+0x240/0x300, .magic: 00000000, .owner: ip/601, .owner_cpu: 1 
[   56.253429][    C1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[   56.253722][    C1] Call Trace:
[   56.253828][    C1]  <IRQ>
[ 56.253899][ C1] dump_stack_lvl (lib/dump_stack.c:122) 
[ 56.254042][ C1] do_raw_spin_unlock (kernel/locking/spinlock_debug.c:100 kernel/locking/spinlock_debug.c:141) 
[ 56.254182][ C1] _raw_spin_unlock (./arch/x86/include/asm/preempt.h:94 ./include/linux/spinlock_api_smp.h:143 kernel/locking/spinlock.c:186) 
[ 56.254322][ C1] net_tx_action (./include/net/sch_generic.h:226 ./include/net/sch_generic.h:217 ./include/net/pkt_sched.h:128 ./include/net/pkt_sched.h:124 net/core/dev.c:5323) 
[ 56.254460][ C1] handle_softirqs (kernel/softirq.c:554) 
[ 56.254595][ C1] ? dev_deactivate_many (./include/linux/bottom_half.h:33 ./include/linux/netdevice.h:4448 net/sched/sch_generic.c:571 net/sched/sch_generic.c:1363) 
[ 56.254732][ C1] do_softirq (kernel/softirq.c:455 kernel/softirq.c:442) 
[   56.254831][    C1]  </IRQ>
[   56.254904][    C1]  <TASK>
[ 56.254970][ C1] __local_bh_enable_ip (kernel/softirq.c:382) 
[ 56.255104][ C1] dev_deactivate_many (net/sched/sch_generic.c:1356) 
[ 56.255239][ C1] __dev_close_many (net/core/dev.c:1547) 
[ 56.255371][ C1] ? __pfx___dev_close_many (net/core/dev.c:1522) 
[ 56.255503][ C1] ? hlock_class (./arch/x86/include/asm/bitops.h:227 ./arch/x86/include/asm/bitops.h:239 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:227) 
[ 56.255639][ C1] dev_close_many (net/core/dev.c:1585) 
[ 56.255771][ C1] ? __pfx_dev_close_many (net/core/dev.c:1575) 
[ 56.255903][ C1] ? find_held_lock (kernel/locking/lockdep.c:5249) 
[ 56.256037][ C1] unregister_netdevice_many_notify (net/core/dev.c:11321) 
[ 56.256205][ C1] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 56.256334][ C1] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5724) 
[ 56.256465][ C1] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 56.256596][ C1] ? __pfx_unregister_netdevice_many_notify (net/core/dev.c:11288) 
[ 56.256758][ C1] ? sock_def_readable (./include/linux/rcupdate.h:336 ./include/linux/rcupdate.h:869 net/core/sock.c:3377) 
[ 56.256891][ C1] ? mutex_is_locked (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-long.h:38 ./include/linux/atomic/atomic-instrumented.h:3189 kernel/locking/mutex.c:81 kernel/locking/mutex.c:91) 
[ 56.257021][ C1] ? rtnl_is_locked (net/core/rtnetlink.c:164) 
[ 56.257165][ C1] ? unregister_netdevice_queue (net/core/dev.c:11273) 
[ 56.257340][ C1] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11272) 
[ 56.257502][ C1] ? __pfx_validate_chain (kernel/locking/lockdep.c:3824) 
[ 56.257632][ C1] ? __pfx_unregister_netdevice_queue (net/core/dev.c:11272) 
[ 56.257796][ C1] rtnl_dellink (net/core/rtnetlink.c:3254 net/core/rtnetlink.c:3304) 
[ 56.257927][ C1] ? hlock_class (./arch/x86/include/asm/bitops.h:227 ./arch/x86/include/asm/bitops.h:239 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:227) 
[ 56.258057][ C1] ? __pfx_rtnl_dellink (net/core/rtnetlink.c:3260) 
[ 56.258199][ C1] ? trace_contention_end (./include/trace/events/lock.h:122 (discriminator 52)) 
[ 56.258331][ C1] ? __mutex_lock (./arch/x86/include/asm/preempt.h:94 kernel/locking/mutex.c:618 kernel/locking/mutex.c:752) 
[ 56.258464][ C1] ? find_held_lock (kernel/locking/lockdep.c:5249) 
[ 56.258603][ C1] ? rtnetlink_rcv_msg (net/core/rtnetlink.c:6645) 
[ 56.258741][ C1] ? __pfx___mutex_lock (kernel/locking/mutex.c:751) 
[ 56.258873][ C1] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 56.259003][ C1] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5724) 
[ 56.259135][ C1] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 56.259272][ C1] rtnetlink_rcv_msg (net/core/rtnetlink.c:6647) 
[ 56.259404][ C1] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6541) 
[ 56.259536][ C1] ? hlock_class (./arch/x86/include/asm/bitops.h:227 ./arch/x86/include/asm/bitops.h:239 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:227) 
[ 56.259667][ C1] ? mark_lock (kernel/locking/lockdep.c:4655 (discriminator 3)) 
[ 56.259769][ C1] ? __lock_acquire (kernel/locking/lockdep.c:5142) 
[ 56.259900][ C1] netlink_rcv_skb (net/netlink/af_netlink.c:2550) 
[ 56.260034][ C1] ? __pfx_rtnetlink_rcv_msg (net/core/rtnetlink.c:6541) 
[ 56.260166][ C1] ? __pfx_netlink_rcv_skb (net/netlink/af_netlink.c:2527) 
[ 56.260301][ C1] ? netlink_deliver_tap (./include/linux/rcupdate.h:336 ./include/linux/rcupdate.h:869 net/netlink/af_netlink.c:340) 
[ 56.260436][ C1] ? netlink_deliver_tap (./include/linux/rcupdate.h:336 ./include/linux/rcupdate.h:869 ./include/net/netns/generic.h:48 net/netlink/af_netlink.c:333) 
[ 56.260568][ C1] netlink_unicast (net/netlink/af_netlink.c:1331 net/netlink/af_netlink.c:1357) 
[ 56.260700][ C1] ? __pfx_netlink_unicast (net/netlink/af_netlink.c:1342) 
[ 56.260833][ C1] ? find_held_lock (kernel/locking/lockdep.c:5249) 
[ 56.260965][ C1] netlink_sendmsg (net/netlink/af_netlink.c:1901) 
[ 56.261096][ C1] ? __pfx_netlink_sendmsg (net/netlink/af_netlink.c:1820) 
[ 56.261228][ C1] ? __might_fault (mm/memory.c:6388 mm/memory.c:6381) 
[ 56.261362][ C1] ? __import_iovec (lib/iov_iter.c:1263 lib/iov_iter.c:1279) 
[ 56.261498][ C1] ____sys_sendmsg (net/socket.c:730 net/socket.c:745 net/socket.c:2597) 
[ 56.261632][ C1] ? __pfx_____sys_sendmsg (net/socket.c:2543) 
[ 56.261765][ C1] ? __pfx_copy_msghdr_from_user (net/socket.c:2523) 
[ 56.261929][ C1] ? __pfx_validate_chain (kernel/locking/lockdep.c:3824) 
[ 56.262063][ C1] ___sys_sendmsg (net/socket.c:2653) 
[ 56.262195][ C1] ? __pfx____sys_sendmsg (net/socket.c:2640) 
[ 56.262327][ C1] ? find_held_lock (kernel/locking/lockdep.c:5249) 
[ 56.262459][ C1] ? __lock_release (kernel/locking/lockdep.c:5435) 
[ 56.262594][ C1] ? __debug_check_no_obj_freed (lib/debugobjects.c:1001) 
[ 56.262762][ C1] ? __pfx___lock_release (kernel/locking/lockdep.c:5411) 
[ 56.262893][ C1] ? __pfx_do_raw_spin_lock (kernel/locking/spinlock_debug.c:114) 
[ 56.263026][ C1] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4299 kernel/locking/lockdep.c:4358) 
[ 56.263189][ C1] ? __fget_light (./include/linux/atomic/atomic-arch-fallback.h:479 ./include/linux/atomic/atomic-instrumented.h:50 fs/file.c:1145) 
[ 56.263323][ C1] __sys_sendmsg (./include/linux/file.h:34 net/socket.c:2682) 
[ 56.263456][ C1] ? __pfx___sys_sendmsg (net/socket.c:2668) 
[ 56.263598][ C1] ? __virt_addr_valid (./arch/x86/include/asm/preempt.h:94 ./include/linux/rcupdate.h:953 ./include/linux/mmzone.h:2034 arch/x86/mm/physaddr.c:65) 
[ 56.263737][ C1] do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83) 
[ 56.263869][ C1] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) 
[   56.264034][    C1] RIP: 0033:0x7fa949cfe7b7
[ 56.264172][ C1] Code: 0a 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b9 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10
All code
========
   0:	0a 00                	or     (%rax),%al
   2:	f7 d8                	neg    %eax
   4:	64 89 02             	mov    %eax,%fs:(%rdx)
   7:	48 c7 c0 ff ff ff ff 	mov    $0xffffffffffffffff,%rax
   e:	eb b9                	jmp    0xffffffffffffffc9
  10:	0f 1f 00             	nopl   (%rax)
  13:	f3 0f 1e fa          	endbr64
  17:	64 8b 04 25 18 00 00 	mov    %fs:0x18,%eax
  1e:	00 
  1f:	85 c0                	test   %eax,%eax
  21:	75 10                	jne    0x33
  23:	b8 2e 00 00 00       	mov    $0x2e,%eax
  28:	0f 05                	syscall
  2a:*	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax		<-- trapping instruction
  30:	77 51                	ja     0x83
  32:	c3                   	ret
  33:	48 83 ec 28          	sub    $0x28,%rsp
  37:	89 54 24 1c          	mov    %edx,0x1c(%rsp)
  3b:	48 89 74 24 10       	mov    %rsi,0x10(%rsp)

Code starting with the faulting instruction
===========================================
   0:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
   6:	77 51                	ja     0x59
   8:	c3                   	ret
   9:	48 83 ec 28          	sub    $0x28,%rsp
   d:	89 54 24 1c          	mov    %edx,0x1c(%rsp)
  11:	48 89 74 24 10       	mov    %rsi,0x10(%rsp)
[   56.264636][    C1] RSP: 002b:00007ffec3f2a578 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[   56.264839][    C1] RAX: ffffffffffffffda RBX: 00007ffec3f2acb0 RCX: 00007fa949cfe7b7
[   56.265034][    C1] RDX: 0000000000000000 RSI: 00007ffec3f2a5e0 RDI: 0000000000000005
[   56.265232][    C1] RBP: 0000000000000002 R08: 0000000000000003 R09: 0000000000000078
[   56.265429][    C1] R10: 00007fa949bbc4a8 R11: 0000000000000246 R12: 0000000000000002


Finger prints:
do_raw_spin_unlock:_raw_spin_unlock:net_tx_action:handle_softirqs:do_softirq