============================================ WARNING: possible recursive locking detected 6.3.0-rc6-syzkaller-01689-g99676a576641 #0 Not tainted -------------------------------------------- syz-executor.0/5555 is trying to acquire lock: ffff888076bef8d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff888076bef8d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4363 [inline] ffff888076bef8d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x2ccf/0x3b30 net/core/dev.c:4241 but task is already holding lock: ffff888023c1c4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff888023c1c4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4363 [inline] ffff888023c1c4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x31c/0xc30 net/sched/sch_generic.c:340 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(_xmit_ETHER#2); lock(_xmit_ETHER#2); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by syz-executor.0/5555: #0: ffffffff8c7955c0 (rcu_read_lock){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:95 [inline] #0: ffffffff8c7955c0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x29c/0x22d0 net/ipv4/ip_output.c:215 #1: ffffffff8c795560 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x22c/0x3b30 net/core/dev.c:4162 #2: ffff888020a8f258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:360 [inline] #2: ffff888020a8f258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:187 [inline] #2: ffff888020a8f258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:184 [inline] #2: ffff888020a8f258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3793 [inline] #2: ffff888020a8f258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x12c5/0x3b30 net/core/dev.c:4211 #3: ffff888023c1c4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #3: ffff888023c1c4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4363 [inline] #3: ffff888023c1c4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x31c/0xc30 net/sched/sch_generic.c:340 #4: ffffffff8c7955c0 (rcu_read_lock){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:95 [inline] #4: ffffffff8c7955c0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x29c/0x22d0 net/ipv4/ip_output.c:215 #5: ffffffff8c795560 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x22c/0x3b30 net/core/dev.c:4162 stack backtrace: CPU: 1 PID: 5555 Comm: syz-executor.0 Not tainted 6.3.0-rc6-syzkaller-01689-g99676a576641 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2991 [inline] check_deadlock kernel/locking/lockdep.c:3034 [inline] validate_chain kernel/locking/lockdep.c:3819 [inline] __lock_acquire+0x1362/0x5d40 kernel/locking/lockdep.c:5056 lock_acquire kernel/locking/lockdep.c:5669 [inline] lock_acquire+0x1af/0x520 kernel/locking/lockdep.c:5634 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:350 [inline] __netif_tx_lock include/linux/netdevice.h:4363 [inline] __dev_queue_xmit+0x2ccf/0x3b30 net/core/dev.c:4241 dev_queue_xmit include/linux/netdevice.h:3085 [inline] neigh_resolve_output net/core/neighbour.c:1552 [inline] neigh_resolve_output+0x51b/0x870 net/core/neighbour.c:1532 neigh_output include/net/neighbour.h:544 [inline] ip_finish_output2+0x695/0x22d0 net/ipv4/ip_output.c:229 __ip_finish_output net/ipv4/ip_output.c:307 [inline] __ip_finish_output+0x396/0x650 net/ipv4/ip_output.c:289 ip_finish_output+0x31/0x280 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip_output+0x1a3/0x320 net/ipv4/ip_output.c:431 dst_output include/net/dst.h:458 [inline] ip_local_out+0xb3/0x1a0 net/ipv4/ip_output.c:126 iptunnel_xmit+0x622/0xa50 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0xfc9/0x3170 net/ipv4/ip_tunnel.c:831 erspan_xmit+0x1130/0x2760 net/ipv4/ip_gre.c:715 __netdev_start_xmit include/linux/netdevice.h:4912 [inline] netdev_start_xmit include/linux/netdevice.h:4926 [inline] xmit_one net/core/dev.c:3579 [inline] dev_hard_start_xmit+0x187/0x700 net/core/dev.c:3595 sch_direct_xmit+0x1a3/0xc30 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3806 [inline] __dev_queue_xmit+0x14ed/0x3b30 net/core/dev.c:4211 dev_queue_xmit include/linux/netdevice.h:3085 [inline] neigh_resolve_output net/core/neighbour.c:1552 [inline] neigh_resolve_output+0x51b/0x870 net/core/neighbour.c:1532 neigh_output include/net/neighbour.h:544 [inline] ip_finish_output2+0x695/0x22d0 net/ipv4/ip_output.c:229 __ip_finish_output net/ipv4/ip_output.c:307 [inline] __ip_finish_output+0x396/0x650 net/ipv4/ip_output.c:289 ip_finish_output+0x31/0x280 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip_output+0x1a3/0x320 net/ipv4/ip_output.c:431 dst_output include/net/dst.h:458 [inline] ip_local_out net/ipv4/ip_output.c:126 [inline] ip_send_skb+0xd8/0x260 net/ipv4/ip_output.c:1587 udp_send_skb+0x73a/0x1490 net/ipv4/udp.c:978 udp_sendmsg+0x1b86/0x27e0 net/ipv4/udp.c:1265 udpv6_sendmsg+0x180a/0x2d50 net/ipv6/udp.c:1401 inet6_sendmsg+0x9d/0xe0 net/ipv6/af_inet6.c:651 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg+0xde/0x190 net/socket.c:747 ____sys_sendmsg+0x334/0x900 net/socket.c:2501 ___sys_sendmsg+0x110/0x1b0 net/socket.c:2555 __sys_sendmmsg+0x18f/0x460 net/socket.c:2641 __do_sys_sendmmsg net/socket.c:2670 [inline] __se_sys_sendmmsg net/socket.c:2667 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2667 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 RIP: 0033:0x7fdae7c88a39 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdae8d37188 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007fdae7d9bf60 RCX: 00007fdae7c88a39 RDX: 0000000000000001 RSI: 0000000020004d80 RDI: 0000000000000004 RBP: 00007fdae7ce2e8f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000004000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffcbf8da85f R14: 00007fdae8d37300 R15: 0000000000022000