syzbot

============================================
WARNING: possible recursive locking detected
6.0.0-rc4-syzkaller #0 Not tainted
--------------------------------------------
syz-executor153/3644 is trying to acquire lock:
ffff88801ceba218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline]
ffff88801ceba218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3847 [inline]
ffff88801ceba218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x2fb8/0x3ad0 net/core/dev.c:4222

but task is already holding lock:
ffff888026882258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:359 [inline]
ffff888026882258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:187 [inline]
ffff888026882258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:184 [inline]
ffff888026882258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3804 [inline]
ffff888026882258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x133c/0x3ad0 net/core/dev.c:4222

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

       CPU0
       ----
  lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
  lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

5 locks held by syz-executor153/3644:
 #0: ffffffff8bf868a0 (rcu_read_lock_bh){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:95 [inline]
 #0: ffffffff8bf868a0 (rcu_read_lock_bh){....}-{1:2}, at: ip_finish_output2+0x292/0x2170 net/ipv4/ip_output.c:214
 #1: ffffffff8bf868a0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x22f/0x3ad0 net/core/dev.c:4173
 #2: ffff888026882258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:359 [inline]
 #2: ffff888026882258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:187 [inline]
 #2: ffff888026882258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:184 [inline]
 #2: ffff888026882258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3804 [inline]
 #2: ffff888026882258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x133c/0x3ad0 net/core/dev.c:4222
 #3: ffffffff8bf868a0 (rcu_read_lock_bh){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:95 [inline]
 #3: ffffffff8bf868a0 (rcu_read_lock_bh){....}-{1:2}, at: ip_finish_output2+0x292/0x2170 net/ipv4/ip_output.c:214
 #4: ffffffff8bf868a0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x22f/0x3ad0 net/core/dev.c:4173

stack backtrace:
CPU: 1 PID: 3644 Comm: syz-executor153 Not tainted 6.0.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_deadlock_bug kernel/locking/lockdep.c:2988 [inline]
 check_deadlock kernel/locking/lockdep.c:3031 [inline]
 validate_chain kernel/locking/lockdep.c:3816 [inline]
 __lock_acquire.cold+0x116/0x3a7 kernel/locking/lockdep.c:5053
 lock_acquire kernel/locking/lockdep.c:5666 [inline]
 lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:349 [inline]
 __dev_xmit_skb net/core/dev.c:3847 [inline]
 __dev_queue_xmit+0x2fb8/0x3ad0 net/core/dev.c:4222
 dev_queue_xmit include/linux/netdevice.h:3008 [inline]
 neigh_hh_output include/net/neighbour.h:535 [inline]
 neigh_output include/net/neighbour.h:549 [inline]
 ip_finish_output2+0x14d3/0x2170 net/ipv4/ip_output.c:228
 __ip_finish_output net/ipv4/ip_output.c:306 [inline]
 __ip_finish_output+0x396/0x650 net/ipv4/ip_output.c:288
 ip_finish_output+0x2d/0x280 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip_output+0x19f/0x310 net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:451 [inline]
 ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:126
 iptunnel_xmit+0x67a/0x9e0 net/ipv4/ip_tunnel_core.c:82
 ip_tunnel_xmit+0x143f/0x3170 net/ipv4/ip_tunnel.c:813
 gre_tap_xmit+0x504/0x630 net/ipv4/ip_gre.c:743
 __netdev_start_xmit include/linux/netdevice.h:4819 [inline]
 netdev_start_xmit include/linux/netdevice.h:4833 [inline]
 xmit_one net/core/dev.c:3590 [inline]
 dev_hard_start_xmit+0x183/0x880 net/core/dev.c:3606
 sch_direct_xmit+0x19f/0xbe0 net/sched/sch_generic.c:342
 __dev_xmit_skb net/core/dev.c:3817 [inline]
 __dev_queue_xmit+0x1568/0x3ad0 net/core/dev.c:4222
 dev_queue_xmit include/linux/netdevice.h:3008 [inline]
 neigh_hh_output include/net/neighbour.h:535 [inline]
 neigh_output include/net/neighbour.h:549 [inline]
 ip_finish_output2+0x14d3/0x2170 net/ipv4/ip_output.c:228
 __ip_finish_output net/ipv4/ip_output.c:306 [inline]
 __ip_finish_output+0x396/0x650 net/ipv4/ip_output.c:288
 ip_finish_output+0x2d/0x280 net/ipv4/ip_output.c:316
 NF_HOOK_COND include/linux/netfilter.h:296 [inline]
 ip_output+0x19f/0x310 net/ipv4/ip_output.c:430
 dst_output include/net/dst.h:451 [inline]
 ip_local_out net/ipv4/ip_output.c:126 [inline]
 ip_send_skb+0xd4/0x260 net/ipv4/ip_output.c:1589
 udp_send_skb+0x725/0x1430 net/ipv4/udp.c:969
 udp_sendmsg+0x1bb8/0x2740 net/ipv4/udp.c:1256
 udpv6_sendmsg+0x17da/0x2c70 net/ipv6/udp.c:1365
 inet6_sendmsg+0x99/0xe0 net/ipv6/af_inet6.c:653
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:734
 ____sys_sendmsg+0x334/0x810 net/socket.c:2482
 ___sys_sendmsg+0x110/0x1b0 net/socket.c:2536
 __sys_sendmmsg+0x18b/0x460 net/socket.c:2622
 __do_sys_sendmmsg net/socket.c:2651 [inline]
 __se_sys_sendmmsg net/socket.c:2648 [inline]
 __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2648
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f30b21b7da9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffee1d01c98 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007ffee1d01cc0 RCX: 00007f30b21b7da9
RDX: 0000000000026700 RSI: 00000000200092c0 RDI: 0000000000000005
RBP: 0000000000000000 R08: 000000000000000d R09: 000000000000000d
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffee1d01cb0
R13: 00000000000f4240 R14: 000000000000e28b R15: 00007ffee1d01ca4
 </TASK>
IPv6: ADDRCONF(NETDEV_CHANGE): vcan0: link becomes ready
chnl_net:chnl_net_open(): err: Unable to register and open device, Err:-19
caif:caif_disconnect_client(): nothing to disconnect
chnl_net:chnl_flowctrl_cb(): NET flowctrl func called flow: CLOSE/DEINIT
chnl_net:chnl_net_open(): state disconnected