IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
TCP: request_sock_TCP: Possible SYN flooding on port 20003. Sending cookies.  Check SNMP counters.

============================================
WARNING: possible recursive locking detected
4.16.0-rc2+ #247 Not tainted
--------------------------------------------
syzkaller232072/4280 is trying to acquire lock:
 (sk_lock-AF_SMC){+.+.}, at: [<000000003c81ac0a>] lock_sock include/net/sock.h:1464 [inline]
 (sk_lock-AF_SMC){+.+.}, at: [<000000003c81ac0a>] smc_close_non_accepted+0x1d/0x370 net/smc/af_smc.c:664

but task is already holding lock:
 (sk_lock-AF_SMC){+.+.}, at: [<00000000952086ed>] lock_sock include/net/sock.h:1464 [inline]
 (sk_lock-AF_SMC){+.+.}, at: [<00000000952086ed>] smc_close_wait_listen_clcsock net/smc/smc_close.c:47 [inline]
 (sk_lock-AF_SMC){+.+.}, at: [<00000000952086ed>] smc_close_active+0x8d9/0x11f0 net/smc/smc_close.c:207

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

       CPU0
       ----
  lock(sk_lock-AF_SMC);
  lock(sk_lock-AF_SMC);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

1 lock held by syzkaller232072/4280:
 #0:  (sk_lock-AF_SMC){+.+.}, at: [<00000000952086ed>] lock_sock include/net/sock.h:1464 [inline]
 #0:  (sk_lock-AF_SMC){+.+.}, at: [<00000000952086ed>] smc_close_wait_listen_clcsock net/smc/smc_close.c:47 [inline]
 #0:  (sk_lock-AF_SMC){+.+.}, at: [<00000000952086ed>] smc_close_active+0x8d9/0x11f0 net/smc/smc_close.c:207

stack backtrace:
CPU: 0 PID: 4280 Comm: syzkaller232072 Not tainted 4.16.0-rc2+ #247
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+0x194/0x24d lib/dump_stack.c:53
 print_deadlock_bug kernel/locking/lockdep.c:1761 [inline]
 check_deadlock kernel/locking/lockdep.c:1805 [inline]
 validate_chain kernel/locking/lockdep.c:2401 [inline]
 __lock_acquire+0xe8f/0x3e00 kernel/locking/lockdep.c:3431
 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
 lock_sock_nested+0xc2/0x110 net/core/sock.c:2781
 lock_sock include/net/sock.h:1464 [inline]
 smc_close_non_accepted+0x1d/0x370 net/smc/af_smc.c:664
 smc_close_cleanup_listen net/smc/smc_close.c:30 [inline]
 smc_close_active+0x9aa/0x11f0 net/smc/smc_close.c:209
 smc_release+0x379/0x580 net/smc/af_smc.c:125
 sock_release+0x8d/0x1e0 net/socket.c:594
 sock_close+0x16/0x20 net/socket.c:1149
 __fput+0x327/0x7e0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x199/0x270 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x9bb/0x1ad0 kernel/exit.c:865
 do_group_exit+0x149/0x400 kernel/exit.c:968
 get_signal+0x73a/0x16d0 kernel/signal.c:2469
 do_signal+0x90/0x1e90 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0x258/0x2f0 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x6e5/0x940 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x446bc9
RSP: 002b:00007fb04b3eed58 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00000000006dcc24 RCX: 0000000000446bc9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000006dcc24
RBP: 0000000000000000 R08: 0000000020000080 R09: 0000000020000080
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc20
R13: 00007ffd2d6a6f2f R14: 00007fb04b3ef9c0 R15: 0000000000000005