============================================ WARNING: possible recursive locking detected 4.16.0-rc4+ #256 Not tainted -------------------------------------------- syz-executor1/24459 is trying to acquire lock: (_xmit_ETHER#2){+.-.}, at: [<000000008d9922b6>] spin_lock include/linux/spinlock.h:310 [inline] (_xmit_ETHER#2){+.-.}, at: [<000000008d9922b6>] __netif_tx_lock include/linux/netdevice.h:3561 [inline] (_xmit_ETHER#2){+.-.}, at: [<000000008d9922b6>] sch_direct_xmit+0x361/0x1140 net/sched/sch_generic.c:325 but task is already holding lock: (_xmit_ETHER#2){+.-.}, at: [<000000008d9922b6>] spin_lock include/linux/spinlock.h:310 [inline] (_xmit_ETHER#2){+.-.}, at: [<000000008d9922b6>] __netif_tx_lock include/linux/netdevice.h:3561 [inline] (_xmit_ETHER#2){+.-.}, at: [<000000008d9922b6>] 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-executor1/24459: #0: (rcu_read_lock_bh){....}, at: [<0000000062ee752c>] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #0: (rcu_read_lock_bh){....}, at: [<0000000062ee752c>] ip6_finish_output2+0x23d/0x23a0 net/ipv6/ip6_output.c:106 #1: (rcu_read_lock_bh){....}, at: [<0000000066a022ef>] __dev_queue_xmit+0x2f6/0x2f30 net/core/dev.c:3483 #2: (_xmit_ETHER#2){+.-.}, at: [<000000008d9922b6>] spin_lock include/linux/spinlock.h:310 [inline] #2: (_xmit_ETHER#2){+.-.}, at: [<000000008d9922b6>] __netif_tx_lock include/linux/netdevice.h:3561 [inline] #2: (_xmit_ETHER#2){+.-.}, at: [<000000008d9922b6>] sch_direct_xmit+0x361/0x1140 net/sched/sch_generic.c:325 #3: (rcu_read_lock){....}, at: [<00000000309b2ad5>] icmpv6_send+0x0/0x280 net/ipv6/ip6_icmp.c:31 #4: (k-slock-AF_INET6){+.-.}, at: [<0000000030d63ad7>] spin_trylock include/linux/spinlock.h:320 [inline] #4: (k-slock-AF_INET6){+.-.}, at: [<0000000030d63ad7>] icmpv6_xmit_lock net/ipv6/icmp.c:119 [inline] #4: (k-slock-AF_INET6){+.-.}, at: [<0000000030d63ad7>] icmp6_send+0x1250/0x2bb0 net/ipv6/icmp.c:528 #5: (rcu_read_lock){....}, at: [<0000000084b2a8ad>] icmp6_send+0x1d37/0x2bb0 net/ipv6/icmp.c:563 #6: (rcu_read_lock_bh){....}, at: [<0000000062ee752c>] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #6: (rcu_read_lock_bh){....}, at: [<0000000062ee752c>] ip6_finish_output2+0x23d/0x23a0 net/ipv6/ip6_output.c:106 #7: (rcu_read_lock){....}, at: [<00000000308ef4e1>] ip6_nd_hdr net/ipv6/ndisc.c:449 [inline] #7: (rcu_read_lock){....}, at: [<00000000308ef4e1>] ndisc_send_skb+0x826/0x1370 net/ipv6/ndisc.c:485 #8: (rcu_read_lock_bh){....}, at: [<0000000062ee752c>] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #8: (rcu_read_lock_bh){....}, at: [<0000000062ee752c>] ip6_finish_output2+0x23d/0x23a0 net/ipv6/ip6_output.c:106 #9: (rcu_read_lock_bh){....}, at: [<0000000066a022ef>] __dev_queue_xmit+0x2f6/0x2f30 net/core/dev.c:3483 stack backtrace: CPU: 1 PID: 24459 Comm: syz-executor1 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/0x23a0 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:443 [inline] NF_HOOK include/linux/netfilter.h:288 [inline] ndisc_send_skb+0xac4/0x1370 net/ipv6/ndisc.c:491 ndisc_send_ns+0x38a/0x870 net/ipv6/ndisc.c:633 ndisc_solicit+0x383/0x5c0 net/ipv6/ndisc.c:725 neigh_probe+0xc3/0x100 net/core/neighbour.c:899 __neigh_event_send+0x927/0x1040 net/core/neighbour.c:1055 neigh_event_send include/net/neighbour.h:435 [inline] neigh_resolve_output+0x62b/0xa00 net/core/neighbour.c:1334 neigh_output include/net/neighbour.h:482 [inline] ip6_finish_output2+0xb4a/0x23a0 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:443 [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+0x2244/0x2bb0 net/ipv6/icmp.c:582 icmpv6_send+0x142/0x280 net/ipv6/ip6_icmp.c:43 ip6_link_failure+0x94/0x570 net/ipv6/route.c:2005 dst_link_failure include/net/dst.h:426 [inline] ip_tunnel_xmit+0x2857/0x3550 net/ipv4/ip_tunnel.c:791 __gre_xmit+0x546/0x8b0 net/ipv4/ip_gre.c:449 erspan_xmit+0x779/0x22a0 net/ipv4/ip_gre.c:728 __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/0x23a0 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:443 [inline] NF_HOOK include/linux/netfilter.h:288 [inline] rawv6_send_hdrinc net/ipv6/raw.c:678 [inline] rawv6_sendmsg+0x2836/0x40c0 net/ipv6/raw.c:924 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:764 sock_sendmsg_nosec net/socket.c:630 [inline] sock_sendmsg+0xca/0x110 net/socket.c:640 ___sys_sendmsg+0x767/0x8b0 net/socket.c:2046 __sys_sendmsg+0xe5/0x210 net/socket.c:2080 C_SYSC_sendmsg net/compat.c:739 [inline] compat_SyS_sendmsg+0x2a/0x40 net/compat.c:737 do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 RIP: 0023:0xf7fa5c99 RSP: 002b:00000000f77a109c EFLAGS: 00000286 ORIG_RAX: 0000000000000172 RAX: ffffffffffffffda RBX: 0000000000000013 RCX: 0000000020002980 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000