======================================
| [  712.445478][T25125] 1 lock held by ip/25125:
| [  712.445610][T25125]  #0: ffffffff8c8a1d28 (rtnl_mutex){+.+.}-{4:4}, at: rtm_new_nexthop (net/ipv4/nexthop.c:3216 net/ipv4/nexthop.c:3271)
| [  712.445859][T25125]
| [  712.445859][T25125] stack backtrace:
[  712.446025][T25125] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  712.446027][T25125] Call Trace:
[  712.446029][T25125]  <TASK>
[  712.446030][T25125]  dump_stack_lvl (lib/dump_stack.c:122)
[  712.446036][T25125]  lockdep_rcu_suspicious.cold (kernel/locking/lockdep.c:6877)
[  712.446042][T25125]  fib6_update_sernum (net/ipv6/ip6_fib.c:111 (discriminator 10))
[  712.446046][T25125]  nh_rt_cache_flush (net/ipv4/nexthop.c:2204 (discriminator 4))
[  712.446050][T25125]  replace_nexthop (net/ipv4/nexthop.c:2570)
[  712.446055][T25125]  insert_nexthop (net/ipv4/nexthop.c:2605)
[  712.446059][T25125]  rtm_new_nexthop (net/ipv4/nexthop.c:2971 net/ipv4/nexthop.c:3275)
[  712.446062][T25125]  ? insert_nexthop (net/ipv4/nexthop.c:3246)
[  712.446064][T25125]  ? lock_acquire.part.0 (kernel/locking/lockdep.c:470 kernel/locking/lockdep.c:5870)
[  712.446067][T25125]  ? find_held_lock (kernel/locking/lockdep.c:5350 (discriminator 1))
[  712.446074][T25125]  ? lock_acquire.part.0 (kernel/locking/lockdep.c:470 kernel/locking/lockdep.c:5870)
[  712.446075][T25125]  ? find_held_lock (kernel/locking/lockdep.c:5350 (discriminator 1))
[  712.446081][T25125]  ? find_held_lock (kernel/locking/lockdep.c:5350 (discriminator 1))
[  712.446083][T25125]  ? insert_nexthop (net/ipv4/nexthop.c:3246)
[  712.446085][T25125]  ? __lock_release.isra.0 (kernel/locking/lockdep.c:5536)
[  712.446089][T25125]  ? insert_nexthop (net/ipv4/nexthop.c:3246)
[  712.446091][T25125]  rtnetlink_rcv_msg (net/core/rtnetlink.c:6958)
[  712.446096][T25125]  ? rtnl_fdb_dump (net/core/rtnetlink.c:6861)
[  712.446099][T25125]  ? __lock_acquire (kernel/locking/lockdep.c:5237 (discriminator 1))
[  712.446102][T25125]  ? lock_acquire.part.0 (kernel/locking/lockdep.c:470 kernel/locking/lockdep.c:5870)
[  712.446104][T25125]  ? find_held_lock (kernel/locking/lockdep.c:5350 (discriminator 1))
[  712.446107][T25125]  netlink_rcv_skb (net/netlink/af_netlink.c:2550)
[  712.446110][T25125]  ? rtnl_fdb_dump (net/core/rtnetlink.c:6861)
[  712.446113][T25125]  ? netlink_ack (net/netlink/af_netlink.c:2527)
[  712.446119][T25125]  ? netlink_deliver_tap (./include/linux/rcupdate.h:322 (discriminator 1) ./include/linux/rcupdate.h:881 (discriminator 1) ./include/net/netns/generic.h:48 (discriminator 1) net/netlink/af_netlink.c:333 (discriminator 1))
[  712.446121][T25125]  ? netlink_deliver_tap (./include/linux/rcupdate.h:322 (discriminator 1) ./include/linux/rcupdate.h:881 (discriminator 1) net/netlink/af_netlink.c:340 (discriminator 1))
[  712.446125][T25125]  netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344)
[  712.446129][T25125]  ? netlink_attachskb (net/netlink/af_netlink.c:1329)
[  712.446130][T25125]  ? __alloc_skb (./include/linux/bottom_half.h:20 (discriminator 1) net/core/skbuff.c:695 (discriminator 1))
[  712.446133][T25125]  ? napi_skb_cache_get (net/core/skbuff.c:674)
[  712.446136][T25125]  ? __lock_acquire (kernel/locking/lockdep.c:5237 (discriminator 1))
[  712.446139][T25125]  netlink_sendmsg (net/netlink/af_netlink.c:1894)
[  712.446142][T25125]  ? netlink_unicast (net/netlink/af_netlink.c:1813)
[  712.446145][T25125]  ? __might_fault (mm/memory.c:7217 (discriminator 4))
[  712.446151][T25125]  ____sys_sendmsg (net/socket.c:727 (discriminator 4) net/socket.c:742 (discriminator 4) net/socket.c:2592 (discriminator 4))
[  712.446153][T25125]  ? copy_msghdr_from_user (net/socket.c:2532)
[  712.446155][T25125]  ? get_timestamp.constprop.0 (net/socket.c:2538)
[  712.446157][T25125]  ? move_addr_to_kernel (net/socket.c:2518)
[  712.446161][T25125]  ? lock_acquire.part.0 (kernel/locking/lockdep.c:470 kernel/locking/lockdep.c:5870)
[  712.446162][T25125]  ? find_held_lock (kernel/locking/lockdep.c:5350 (discriminator 1))
[  712.446166][T25125]  ___sys_sendmsg (net/socket.c:2648)
[  712.446168][T25125]  ? copy_msghdr_from_user (net/socket.c:2635)
[  712.446169][T25125]  ? __lock_release.isra.0 (kernel/locking/lockdep.c:5536)
[  712.446180][T25125]  ? lock_vma_under_rcu (./include/linux/rcupdate.h:322 (discriminator 1) ./include/linux/rcupdate.h:881 (discriminator 1) mm/mmap_lock.c:329 (discriminator 1))
[  712.446185][T25125]  __sys_sendmsg (net/socket.c:2678 (discriminator 1))
[  712.446188][T25125]  ? __sys_sendmsg_sock (net/socket.c:2663)
[  712.446193][T25125]  ? do_user_addr_fault (./arch/x86/include/asm/atomic.h:93 (discriminator 4) ./include/linux/atomic/atomic-arch-fallback.h:949 (discriminator 4) ./include/linux/atomic/atomic-instrumented.h:401 (discriminator 4) ./include/linux/refcount.h:389 (discriminator 4) ./include/linux/refcount.h:432 (discriminator 4) ./include/linux/mmap_lock.h:196 (discriminator 4) ./include/linux/mmap_lock.h:217 (discriminator 4) ./include/linux/mmap_lock.h:264 (discriminator 4) arch/x86/mm/fault.c:1336 (discriminator 4))
[  712.446197][T25125]  ? rcu_is_watching (./include/linux/context_tracking.h:128 (discriminator 1) kernel/rcu/tree.c:752 (discriminator 1))
[  712.446200][T25125]  ? rcu_is_watching (./include/linux/context_tracking.h:128 (discriminator 1) kernel/rcu/tree.c:752 (discriminator 1))
[  712.446203][T25125]  do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))
[  712.446207][T25125]  ? exc_page_fault (arch/x86/mm/fault.c:1480 (discriminator 3) arch/x86/mm/fault.c:1527 (discriminator 3))
[  712.446210][T25125]  entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
[  712.446212][T25125] RIP: 0033:0x7f02654b7c5e
[  712.446216][T25125] Code: 4d 89 d8 e8 34 bd 00 00 4c 8b 5d f8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 11 c9 c3 0f 1f 80 00 00 00 00 48 8b 45 10 0f 05 <c9> c3 83 e2 39 83 fa 08 75 e7 e8 13 ff ff ff 0f 1f 00 f3 0f 1e fa
All code
========
   0:	4d 89 d8             	mov    %r11,%r8
   3:	e8 34 bd 00 00       	call   0xbd3c
   8:	4c 8b 5d f8          	mov    -0x8(%rbp),%r11
   c:	41 8b 93 08 03 00 00 	mov    0x308(%r11),%edx
  13:	59                   	pop    %rcx
  14:	5e                   	pop    %rsi
  15:	48 83 f8 fc          	cmp    $0xfffffffffffffffc,%rax
  19:	74 11                	je     0x2c
  1b:	c9                   	leave
  1c:	c3                   	ret
  1d:	0f 1f 80 00 00 00 00 	nopl   0x0(%rax)
  24:	48 8b 45 10          	mov    0x10(%rbp),%rax
  28:	0f 05                	syscall
  2a:*	c9                   	leave		<-- trapping instruction
  2b:	c3                   	ret
  2c:	83 e2 39             	and    $0x39,%edx
  2f:	83 fa 08             	cmp    $0x8,%edx
  32:	75 e7                	jne    0x1b
  34:	e8 13 ff ff ff       	call   0xffffffffffffff4c
  39:	0f 1f 00             	nopl   (%rax)
  3c:	f3 0f 1e fa          	endbr64

Code starting with the faulting instruction
===========================================
   0:	c9                   	leave
   1:	c3                   	ret
   2:	83 e2 39             	and    $0x39,%edx
   5:	83 fa 08             	cmp    $0x8,%edx
   8:	75 e7                	jne    0xfffffffffffffff1
   a:	e8 13 ff ff ff       	call   0xffffffffffffff22
   f:	0f 1f 00             	nopl   (%rax)
  12:	f3 0f 1e fa          	endbr64
[  712.446218][T25125] RSP: 002b:00007ffdb54239f0 EFLAGS: 00000202 ORIG_RAX: 000000000000002e
[  712.446220][T25125] RAX: ffffffffffffffda RBX: 000000000048a910 RCX: 00007f02654b7c5e
[  712.446222][T25125] RDX: 0000000000000000 RSI: 00007ffdb5423ab0 RDI: 0000000000000005
[  712.446223][T25125] RBP: 00007ffdb5423a00 R08: 0000000000000000 R09: 0000000000000000
[  712.446224][T25125] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000


Finger prints:
fib6_update_sernum:nh_rt_cache_flush:replace_nexthop:insert_nexthop:rtm_new_nexthop