syzbot

IPv6: ADDRCONF(NETDEV_CHANGE): macvtap0: link becomes ready
batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): bond0: link becomes ready
============================================
WARNING: possible recursive locking detected
4.14.294-syzkaller #0 Not tainted
--------------------------------------------
syz-executor110/7978 is trying to acquire lock:
 (rtnl_mutex){+.+.}, at: [<ffffffff86fb8c7b>] hsr_dev_destroy+0x1b/0xb0 net/hsr/hsr_device.c:373

but task is already holding lock:
 (rtnl_mutex){+.+.}, at: [<ffffffff85c85a4d>] rtnl_lock net/core/rtnetlink.c:72 [inline]
 (rtnl_mutex){+.+.}, at: [<ffffffff85c85a4d>] rtnetlink_rcv_msg+0x31d/0xb10 net/core/rtnetlink.c:4317

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

       CPU0
       ----
  lock(rtnl_mutex);
  lock(rtnl_mutex);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

1 lock held by syz-executor110/7978:
 #0:  (rtnl_mutex){+.+.}, at: [<ffffffff85c85a4d>] rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0:  (rtnl_mutex){+.+.}, at: [<ffffffff85c85a4d>] rtnetlink_rcv_msg+0x31d/0xb10 net/core/rtnetlink.c:4317

stack backtrace:
CPU: 0 PID: 7978 Comm: syz-executor110 Not tainted 4.14.294-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2022
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/0xe50 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+0xf7c/0x1830 net/core/rtnetlink.c:2730
 rtnetlink_rcv_msg+0x3be/0xb10 net/core/rtnetlink.c:4322
 netlink_rcv_skb+0x125/0x390 net/netlink/af_netlink.c:2454
 netlink_unicast_kernel net/netlink/af_netlink.c:1296 [inline]
 netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1322
 netlink_sendmsg+0x648/0xbc0 net/netlink/af_netlink.c:1893
 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: 0033:0x7fee6c3f99a9
RSP: 002b:00007ffee5330978 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ffee5330988 RCX: 00007fee6c3f99a9
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000005
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffee5330990
R13: 00007ffee53309b0 R14: 0000000000000000 R15: 0000000000000000