Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold+0x10a/0x149 lib/fault-inject.c:149
============================================
 should_failslab+0xd6/0x130 mm/failslab.c:32
WARNING: possible recursive locking detected
 slab_pre_alloc_hook mm/slab.h:421 [inline]
 slab_alloc mm/slab.c:3376 [inline]
 kmem_cache_alloc_trace+0x47/0x3d0 mm/slab.c:3616
4.14.262-syzkaller #0 Not tainted
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 netlbl_unlhsh_add_addr6 net/netlabel/netlabel_unlabeled.c:292 [inline]
 netlbl_unlhsh_add+0x1ed/0x1110 net/netlabel/netlabel_unlabeled.c:437
--------------------------------------------
syz-executor.0/25899 is trying to acquire lock:
 (
rtnl_mutex
){+.+.}, at: [<ffffffff86fb1d7b>] hsr_dev_destroy+0x1b/0xb0 net/hsr/hsr_device.c:373

but task is already holding lock:
 (
 netlbl_unlabel_staticadddef+0x2c6/0x3d0 net/netlabel/netlabel_unlabeled.c:975
rtnl_mutex){+.+.}
, at: [<ffffffff85c8542d>] rtnl_lock net/core/rtnetlink.c:72 [inline]
, at: [<ffffffff85c8542d>] rtnetlink_rcv_msg+0x31d/0xb10 net/core/rtnetlink.c:4315

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
 genl_family_rcv_msg+0x572/0xb20 net/netlink/genetlink.c:600
       ----
  lock(
rtnl_mutex
);
 genl_rcv_msg+0xaf/0x140 net/netlink/genetlink.c:625
  lock(
 netlink_rcv_skb+0x125/0x390 net/netlink/af_netlink.c:2446
rtnl_mutex
);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

1 lock held by syz-executor.0/25899:
 genl_rcv+0x24/0x40 net/netlink/genetlink.c:636
 #0: 
 netlink_unicast_kernel net/netlink/af_netlink.c:1294 [inline]
 netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1320
 (
rtnl_mutex){+.+.}
, at: [<ffffffff85c8542d>] rtnl_lock net/core/rtnetlink.c:72 [inline]
, at: [<ffffffff85c8542d>] rtnetlink_rcv_msg+0x31d/0xb10 net/core/rtnetlink.c:4315

stack backtrace:
 netlink_sendmsg+0x648/0xbc0 net/netlink/af_netlink.c:1891
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:656
 ___sys_sendmsg+0x6c8/0x800 net/socket.c:2062
 __sys_sendmsg+0xa3/0x120 net/socket.c:2096
 SYSC_sendmsg net/socket.c:2107 [inline]
 SyS_sendmsg+0x27/0x40 net/socket.c:2103
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7fb14bd67fe9
RSP: 002b:00007fb14a6dd168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb14be7af60 RCX: 00007fb14bd67fe9
RDX: 0000000000000000 RSI: 00000000200002c0 RDI: 0000000000000004
RBP: 00007fb14a6dd1d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc34d6fadf R14: 00007fb14a6dd300 R15: 0000000000022000
CPU: 1 PID: 25899 Comm: syz-executor.0 Not tainted 4.14.262-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_deadlock_bug kernel/locking/lockdep.c:1800 [inline]
 check_deadlock kernel/locking/lockdep.c:1847 [inline]
 validate_chain kernel/locking/lockdep.c:2448 [inline]
 __lock_acquire.cold+0x180/0x97c kernel/locking/lockdep.c:3491
 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
 __mutex_lock_common kernel/locking/mutex.c:756 [inline]
 __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
 hsr_dev_destroy+0x1b/0xb0 net/hsr/hsr_device.c:373
 register_netdevice+0x83c/0xe40 net/core/dev.c:7729
 hsr_dev_finalize+0x57b/0x800 net/hsr/hsr_device.c:492
 hsr_newlink+0x259/0x3a0 net/hsr/hsr_netlink.c:78
 rtnl_newlink+0xfab/0x1860 net/core/rtnetlink.c:2728
 rtnetlink_rcv_msg+0x3be/0xb10 net/core/rtnetlink.c:4320
 netlink_rcv_skb+0x125/0x390 net/netlink/af_netlink.c:2446
 netlink_unicast_kernel net/netlink/af_netlink.c:1294 [inline]
 netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1320
 netlink_sendmsg+0x648/0xbc0 net/netlink/af_netlink.c:1891
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:656
 ___sys_sendmsg+0x6c8/0x800 net/socket.c:2062
 __sys_sendmsg+0xa3/0x120 net/socket.c:2096
 SYSC_sendmsg net/socket.c:2107 [inline]
 SyS_sendmsg+0x27/0x40 net/socket.c:2103
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f2a6db8cfe9
RSP: 002b:00007f2a6c502168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f2a6dc9ff60 RCX: 00007f2a6db8cfe9
RDX: 0000000000000000 RSI: 00000000200000c0 RDI: 0000000000000004
RBP: 00007f2a6c5021d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007ffdac03ac3f R14: 00007f2a6c502300 R15: 0000000000022000