syzbot

================================
WARNING: inconsistent lock state
6.1.0-rc6-syzkaller #0 Not tainted
--------------------------------
inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-R} usage.
ksoftirqd/0/15 [HC0[0]:SC1[3]:HE1:SE0] takes:
ffff88807d15a7b8 (k-clock-AF_INET){+++-}-{2:2}, at: smc_fback_state_change+0x20/0xc0 net/smc/af_smc.c:799
{SOFTIRQ-ON-W} state was registered at:
  lock_acquire kernel/locking/lockdep.c:5668 [inline]
  lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
  __raw_write_lock include/linux/rwlock_api_smp.h:209 [inline]
  _raw_write_lock+0x2e/0x40 kernel/locking/spinlock.c:300
  l2tp_tunnel_register+0x126/0x1210 net/l2tp/l2tp_core.c:1477
  l2tp_nl_cmd_tunnel_create+0x3d6/0x8b0 net/l2tp/l2tp_netlink.c:245
  genl_family_rcv_msg_doit+0x228/0x320 net/netlink/genetlink.c:756
  genl_family_rcv_msg net/netlink/genetlink.c:833 [inline]
  genl_rcv_msg+0x445/0x780 net/netlink/genetlink.c:850
  netlink_rcv_skb+0x157/0x430 net/netlink/af_netlink.c:2540
  genl_rcv+0x28/0x40 net/netlink/genetlink.c:861
  netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
  netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1345
  netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1921
  sock_sendmsg_nosec net/socket.c:714 [inline]
  sock_sendmsg+0xd3/0x120 net/socket.c:734
  ____sys_sendmsg+0x712/0x8c0 net/socket.c:2482
  ___sys_sendmsg+0x110/0x1b0 net/socket.c:2536
  __sys_sendmsg+0xf7/0x1c0 net/socket.c:2565
  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
  do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
  entry_SYSCALL_64_after_hwframe+0x63/0xcd
irq event stamp: 245260
hardirqs last  enabled at (245260): [<ffffffff814c1e64>] __local_bh_enable_ip+0xa4/0x130 kernel/softirq.c:401
hardirqs last disabled at (245259): [<ffffffff814c1e87>] __local_bh_enable_ip+0xc7/0x130 kernel/softirq.c:378
softirqs last  enabled at (245040): [<ffffffff814c1d91>] run_ksoftirqd kernel/softirq.c:934 [inline]
softirqs last  enabled at (245040): [<ffffffff814c1d91>] run_ksoftirqd+0x31/0x60 kernel/softirq.c:926
softirqs last disabled at (245045): [<ffffffff814c1d91>] run_ksoftirqd kernel/softirq.c:934 [inline]
softirqs last disabled at (245045): [<ffffffff814c1d91>] run_ksoftirqd+0x31/0x60 kernel/softirq.c:926

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

       CPU0
       ----
  lock(k-clock-AF_INET);
  <Interrupt>
    lock(k-clock-AF_INET);

 *** DEADLOCK ***

3 locks held by ksoftirqd/0/15:
 #0: ffffffff8c58fc40 (rcu_read_lock){....}-{1:2}, at: __skb_unlink include/linux/skbuff.h:2324 [inline]
 #0: ffffffff8c58fc40 (rcu_read_lock){....}-{1:2}, at: __skb_dequeue include/linux/skbuff.h:2339 [inline]
 #0: ffffffff8c58fc40 (rcu_read_lock){....}-{1:2}, at: process_backlog+0x38f/0x810 net/core/dev.c:5929
 #1: ffffffff8c58fc40 (rcu_read_lock){....}-{1:2}, at: __skb_pull include/linux/skbuff.h:2609 [inline]
 #1: ffffffff8c58fc40 (rcu_read_lock){....}-{1:2}, at: ip_local_deliver_finish+0x20a/0x4c0 net/ipv4/ip_input.c:230
 #2: ffff88807d15a4b0 (k-slock-AF_INET/1){+.-.}-{2:2}, at: tcp_v4_rcv+0x3429/0x3980 net/ipv4/tcp_ipv4.c:2098

stack backtrace:
CPU: 0 PID: 15 Comm: ksoftirqd/0 Not tainted 6.1.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
 print_usage_bug kernel/locking/lockdep.c:3963 [inline]
 valid_state kernel/locking/lockdep.c:3975 [inline]
 mark_lock_irq kernel/locking/lockdep.c:4178 [inline]
 mark_lock.part.0.cold+0x18/0xd8 kernel/locking/lockdep.c:4634
 mark_lock kernel/locking/lockdep.c:4598 [inline]
 mark_usage kernel/locking/lockdep.c:4521 [inline]
 __lock_acquire+0x14dc/0x56d0 kernel/locking/lockdep.c:5009
 lock_acquire kernel/locking/lockdep.c:5668 [inline]
 lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
 __raw_read_lock_bh include/linux/rwlock_api_smp.h:176 [inline]
 _raw_read_lock_bh+0x3f/0x70 kernel/locking/spinlock.c:252
 smc_fback_state_change+0x20/0xc0 net/smc/af_smc.c:799
 tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6292 [inline]
 tcp_rcv_state_process+0xd7a/0x49a0 net/ipv4/tcp_input.c:6489
 tcp_v4_do_rcv+0x33d/0x9b0 net/ipv4/tcp_ipv4.c:1704
 tcp_v4_rcv+0x36ad/0x3980 net/ipv4/tcp_ipv4.c:2102
 ip_protocol_deliver_rcu+0x9f/0x7c0 net/ipv4/ip_input.c:205
 ip_local_deliver_finish+0x2ec/0x4c0 net/ipv4/ip_input.c:233
 NF_HOOK include/linux/netfilter.h:302 [inline]
 NF_HOOK include/linux/netfilter.h:296 [inline]
 ip_local_deliver+0x1ae/0x200 net/ipv4/ip_input.c:254
 dst_input include/net/dst.h:455 [inline]
 ip_rcv_finish+0x1cf/0x2f0 net/ipv4/ip_input.c:444
 NF_HOOK include/linux/netfilter.h:302 [inline]
 NF_HOOK include/linux/netfilter.h:296 [inline]
 ip_rcv+0xae/0xd0 net/ipv4/ip_input.c:564
 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5489
 __netif_receive_skb+0x1f/0x1c0 net/core/dev.c:5603
 process_backlog+0x3e4/0x810 net/core/dev.c:5931
 __napi_poll+0xb8/0x770 net/core/dev.c:6498
 napi_poll net/core/dev.c:6565 [inline]
 net_rx_action+0xa00/0xde0 net/core/dev.c:6676
 __do_softirq+0x1fb/0xadc kernel/softirq.c:571
 run_ksoftirqd kernel/softirq.c:934 [inline]
 run_ksoftirqd+0x31/0x60 kernel/softirq.c:926
 smpboot_thread_fn+0x659/0xa20 kernel/smpboot.c:164
 kthread+0x2e8/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>