============================================
WARNING: possible recursive locking detected
4.14.108+ #36 Not tainted
--------------------------------------------
syz-executor.5/31736 is trying to acquire lock:
 (_xmit_TUNNEL6#2){+.-.}, at: [<ffffffff8d919fb7>] spin_lock include/linux/spinlock.h:317 [inline]
 (_xmit_TUNNEL6#2){+.-.}, at: [<ffffffff8d919fb7>] __netif_tx_lock include/linux/netdevice.h:3530 [inline]
 (_xmit_TUNNEL6#2){+.-.}, at: [<ffffffff8d919fb7>] __dev_queue_xmit+0x1127/0x1cd0 net/core/dev.c:3521

but task is already holding lock:
 (_xmit_TUNNEL6#2){+.-.}, at: [<ffffffff8d919fb7>] spin_lock include/linux/spinlock.h:317 [inline]
 (_xmit_TUNNEL6#2){+.-.}, at: [<ffffffff8d919fb7>] __netif_tx_lock include/linux/netdevice.h:3530 [inline]
 (_xmit_TUNNEL6#2){+.-.}, at: [<ffffffff8d919fb7>] __dev_queue_xmit+0x1127/0x1cd0 net/core/dev.c:3521

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

       CPU0
       ----
  lock(_xmit_TUNNEL6#2);
  lock(_xmit_TUNNEL6#2);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

6 locks held by syz-executor.5/31736:
 #0:  (rcu_read_lock_bh){....}, at: [<ffffffff8daaa621>] ip_finish_output2+0x211/0x12f0 net/ipv4/ip_output.c:199
 #1:  (rcu_read_lock_bh){....}, at: [<ffffffff8d919043>] __dev_queue_xmit+0x1b3/0x1cd0 net/core/dev.c:3459
 #2:  (_xmit_TUNNEL6#2){+.-.}, at: [<ffffffff8d919fb7>] spin_lock include/linux/spinlock.h:317 [inline]
 #2:  (_xmit_TUNNEL6#2){+.-.}, at: [<ffffffff8d919fb7>] __netif_tx_lock include/linux/netdevice.h:3530 [inline]
 #2:  (_xmit_TUNNEL6#2){+.-.}, at: [<ffffffff8d919fb7>] __dev_queue_xmit+0x1127/0x1cd0 net/core/dev.c:3521
 #3:  (k-slock-AF_INET){+...}, at: [<ffffffff8db7e66d>] spin_trylock include/linux/spinlock.h:327 [inline]
 #3:  (k-slock-AF_INET){+...}, at: [<ffffffff8db7e66d>] icmp_xmit_lock net/ipv4/icmp.c:219 [inline]
 #3:  (k-slock-AF_INET){+...}, at: [<ffffffff8db7e66d>] __icmp_send+0x46d/0x1110 net/ipv4/icmp.c:669
 #4:  (rcu_read_lock_bh){....}, at: [<ffffffff8daaa621>] ip_finish_output2+0x211/0x12f0 net/ipv4/ip_output.c:199
 #5:  (rcu_read_lock_bh){....}, at: [<ffffffff8d919043>] __dev_queue_xmit+0x1b3/0x1cd0 net/core/dev.c:3459

stack backtrace:
CPU: 1 PID: 31736 Comm: syz-executor.5 Not tainted 4.14.108+ #36
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xb9/0x10e lib/dump_stack.c:53
 print_deadlock_bug kernel/locking/lockdep.c:1796 [inline]
 check_deadlock kernel/locking/lockdep.c:1843 [inline]
 validate_chain kernel/locking/lockdep.c:2444 [inline]
 __lock_acquire.cold+0x1da/0xa36 kernel/locking/lockdep.c:3487