============================================ WARNING: possible recursive locking detected 4.16.0-rc4+ #256 Not tainted -------------------------------------------- syz-executor4/21419 is trying to acquire lock: (_xmit_ETHER#2){+.-.}, at: [<00000000667f3c3a>] spin_lock include/linux/spinlock.h:310 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000667f3c3a>] __netif_tx_lock include/linux/netdevice.h:3561 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000667f3c3a>] sch_direct_xmit+0x361/0x1140 net/sched/sch_generic.c:325 but task is already holding lock: (_xmit_ETHER#2){+.-.}, at: [<00000000667f3c3a>] spin_lock include/linux/spinlock.h:310 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000667f3c3a>] __netif_tx_lock include/linux/netdevice.h:3561 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000667f3c3a>] sch_direct_xmit+0x361/0x1140 net/sched/sch_generic.c:325 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 10 locks held by syz-executor4/21419: #0: (sk_lock-AF_INET6){+.+.}, at: [<00000000e2e75f99>] lock_sock include/net/sock.h:1464 [inline] #0: (sk_lock-AF_INET6){+.+.}, at: [<00000000e2e75f99>] sctp_setsockopt+0x31a/0x61d0 net/sctp/socket.c:4116 #1: (rcu_read_lock){....}, at: [<00000000070372dd>] sctp_v6_xmit+0x2e5/0x630 net/sctp/ipv6.c:222 #2: (rcu_read_lock_bh){....}, at: [<0000000002556a4c>] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #2: (rcu_read_lock_bh){....}, at: [<0000000002556a4c>] ip6_finish_output2+0x23d/0x23d0 net/ipv6/ip6_output.c:106 #3: (rcu_read_lock_bh){....}, at: [<00000000f4a4bde2>] __dev_queue_xmit+0x2f6/0x2f30 net/core/dev.c:3483 #4: (_xmit_ETHER#2){+.-.}, at: [<00000000667f3c3a>] spin_lock include/linux/spinlock.h:310 [inline] #4: (_xmit_ETHER#2){+.-.}, at: [<00000000667f3c3a>] __netif_tx_lock include/linux/netdevice.h:3561 [inline] #4: (_xmit_ETHER#2){+.-.}, at: [<00000000667f3c3a>] sch_direct_xmit+0x361/0x1140 net/sched/sch_generic.c:325 #5: (rcu_read_lock){....}, at: [<000000005bc6ecda>] icmpv6_send+0x0/0x280 net/ipv6/ip6_icmp.c:31 #6: (k-slock-AF_INET6){+.-.}, at: [<00000000b9317117>] spin_trylock include/linux/spinlock.h:320 [inline] #6: (k-slock-AF_INET6){+.-.}, at: [<00000000b9317117>] icmpv6_xmit_lock net/ipv6/icmp.c:119 [inline] #6: (k-slock-AF_INET6){+.-.}, at: [<00000000b9317117>] icmp6_send+0x125e/0x2bb0 net/ipv6/icmp.c:528 #7: (rcu_read_lock){....}, at: [<00000000f5b468d0>] icmp6_send+0x1d45/0x2bb0 net/ipv6/icmp.c:563 #8: (rcu_read_lock_bh){....}, at: [<0000000002556a4c>] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #8: (rcu_read_lock_bh){....}, at: [<0000000002556a4c>] ip6_finish_output2+0x23d/0x23d0 net/ipv6/ip6_output.c:106 #9: (rcu_read_lock_bh){....}, at: [<00000000f4a4bde2>] __dev_queue_xmit+0x2f6/0x2f30 net/core/dev.c:3483 stack backtrace: CPU: 1 PID: 21419 Comm: syz-executor4 Not tainted 4.16.0-rc4+ #256 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 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:310 [inline] __netif_tx_lock include/linux/netdevice.h:3561 [inline] sch_direct_xmit+0x361/0x1140 net/sched/sch_generic.c:325 qdisc_restart net/sched/sch_generic.c:393 [inline] __qdisc_run+0x57d/0x19c0 net/sched/sch_generic.c:401 __dev_xmit_skb net/core/dev.c:3217 [inline] __dev_queue_xmit+0xd5e/0x2f30 net/core/dev.c:3517 dev_queue_xmit+0x17/0x20 net/core/dev.c:3582 neigh_resolve_output+0x5e2/0xa00 net/core/neighbour.c:1350 neigh_output include/net/neighbour.h:482 [inline] ip6_finish_output2+0xb4a/0x23d0 net/ipv6/ip6_output.c:120 ip6_finish_output+0x69b/0xaf0 net/ipv6/ip6_output.c:154 NF_HOOK_COND include/linux/netfilter.h:277 [inline] ip6_output+0x1eb/0x840 net/ipv6/ip6_output.c:171 dst_output include/net/dst.h:444 [inline] ip6_local_out+0x95/0x160 net/ipv6/output_core.c:176 ip6_send_skb+0xa1/0x330 net/ipv6/ip6_output.c:1677 ip6_push_pending_frames+0xb3/0xe0 net/ipv6/ip6_output.c:1697 icmpv6_push_pending_frames+0x338/0x520 net/ipv6/icmp.c:288 icmp6_send+0x2252/0x2bb0 net/ipv6/icmp.c:582 icmpv6_send+0x142/0x280 net/ipv6/ip6_icmp.c:43 ip6_link_failure+0x94/0x570 net/ipv6/route.c:2077 dst_link_failure include/net/dst.h:427 [inline] ip_tunnel_xmit+0x2857/0x3550 net/ipv4/ip_tunnel.c:775 __gre_xmit+0x546/0x8b0 net/ipv4/ip_gre.c:449 erspan_xmit+0x779/0x22a0 net/ipv4/ip_gre.c:731 __netdev_start_xmit include/linux/netdevice.h:4066 [inline] netdev_start_xmit include/linux/netdevice.h:4075 [inline] xmit_one net/core/dev.c:3026 [inline] dev_hard_start_xmit+0x24e/0xac0 net/core/dev.c:3042 sch_direct_xmit+0x40d/0x1140 net/sched/sch_generic.c:327 qdisc_restart net/sched/sch_generic.c:393 [inline] __qdisc_run+0x57d/0x19c0 net/sched/sch_generic.c:401 __dev_xmit_skb net/core/dev.c:3217 [inline] __dev_queue_xmit+0xd5e/0x2f30 net/core/dev.c:3517 dev_queue_xmit+0x17/0x20 net/core/dev.c:3582 neigh_resolve_output+0x5e2/0xa00 net/core/neighbour.c:1350 neigh_output include/net/neighbour.h:482 [inline] ip6_finish_output2+0xb4a/0x23d0 net/ipv6/ip6_output.c:120 ip6_finish_output+0x69b/0xaf0 net/ipv6/ip6_output.c:154 NF_HOOK_COND include/linux/netfilter.h:277 [inline] ip6_output+0x1eb/0x840 net/ipv6/ip6_output.c:171 dst_output include/net/dst.h:444 [inline] NF_HOOK include/linux/netfilter.h:288 [inline] ip6_xmit+0xe28/0x2260 net/ipv6/ip6_output.c:277 sctp_v6_xmit+0x438/0x630 net/sctp/ipv6.c:225 sctp_packet_transmit+0x225e/0x3750 net/sctp/output.c:638 sctp_outq_flush+0xabb/0x4060 net/sctp/outqueue.c:911 sctp_outq_uncork+0x5a/0x70 net/sctp/outqueue.c:776 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1807 [inline] sctp_side_effects net/sctp/sm_sideeffect.c:1210 [inline] sctp_do_sm+0x4e0/0x6ed0 net/sctp/sm_sideeffect.c:1181 sctp_primitive_ASSOCIATE+0x9d/0xd0 net/sctp/primitive.c:88 __sctp_connect+0x829/0xca0 net/sctp/socket.c:1235 __sctp_setsockopt_connectx+0x57/0x80 net/sctp/socket.c:1350 sctp_setsockopt_connectx net/sctp/socket.c:1380 [inline] sctp_setsockopt+0x1155/0x61d0 net/sctp/socket.c:4140 sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2980 SYSC_setsockopt net/socket.c:1850 [inline] SyS_setsockopt+0x189/0x360 net/socket.c:1829 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x453e69 RSP: 002b:00007f6419f51c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f6419f526d4 RCX: 0000000000453e69 RDX: 000000000000006e RSI: 0000000000000084 RDI: 0000000000000013 RBP: 000000000072bea0 R08: 000000000000001c R09: 0000000000000000 R10: 0000000020000080 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000566 R14: 00000000006f8230 R15: 0000000000000000