============================================ WARNING: possible recursive locking detected 4.16.0-rc6+ #280 Not tainted -------------------------------------------- syz-executor7/9014 is trying to acquire lock: (_xmit_ETHER#2){+.-.}, at: [<00000000e1d51a8b>] spin_lock include/linux/spinlock.h:310 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000e1d51a8b>] __netif_tx_lock include/linux/netdevice.h:3573 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000e1d51a8b>] sch_direct_xmit+0x361/0x1140 net/sched/sch_generic.c:325 but task is already holding lock: (_xmit_ETHER#2){+.-.}, at: [<00000000e1d51a8b>] spin_lock include/linux/spinlock.h:310 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000e1d51a8b>] __netif_tx_lock include/linux/netdevice.h:3573 [inline] (_xmit_ETHER#2){+.-.}, at: [<00000000e1d51a8b>] 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 11 locks held by syz-executor7/9014: #0: (rcu_read_lock_bh){....}, at: [<000000006d33b3e2>] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #0: (rcu_read_lock_bh){....}, at: [<000000006d33b3e2>] ip_finish_output2+0x2aa/0x1550 net/ipv4/ip_output.c:213 #1: (rcu_read_lock_bh){....}, at: [<00000000e1f5f6d5>] __dev_queue_xmit+0x2fe/0x2fc0 net/core/dev.c:3491 #2: (rcu_read_lock_bh){....}, at: [<000000006d33b3e2>] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #2: (rcu_read_lock_bh){....}, at: [<000000006d33b3e2>] ip_finish_output2+0x2aa/0x1550 net/ipv4/ip_output.c:213 #3: (rcu_read_lock_bh){....}, at: [<00000000e1f5f6d5>] __dev_queue_xmit+0x2fe/0x2fc0 net/core/dev.c:3491 #4: (rcu_read_lock){....}, at: [<000000006889281e>] br_dev_xmit+0x11d/0x1550 net/bridge/br_device.c:43 #5: (rcu_read_lock_bh){....}, at: [<00000000e1f5f6d5>] __dev_queue_xmit+0x2fe/0x2fc0 net/core/dev.c:3491 #6: (_xmit_ETHER#2){+.-.}, at: [<00000000e1d51a8b>] spin_lock include/linux/spinlock.h:310 [inline] #6: (_xmit_ETHER#2){+.-.}, at: [<00000000e1d51a8b>] __netif_tx_lock include/linux/netdevice.h:3573 [inline] #6: (_xmit_ETHER#2){+.-.}, at: [<00000000e1d51a8b>] sch_direct_xmit+0x361/0x1140 net/sched/sch_generic.c:325 #7: (rcu_read_lock_bh){....}, at: [<000000006d33b3e2>] lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #7: (rcu_read_lock_bh){....}, at: [<000000006d33b3e2>] ip_finish_output2+0x2aa/0x1550 net/ipv4/ip_output.c:213 #8: (rcu_read_lock_bh){....}, at: [<00000000e1f5f6d5>] __dev_queue_xmit+0x2fe/0x2fc0 net/core/dev.c:3491 #9: (rcu_read_lock){....}, at: [<000000006889281e>] br_dev_xmit+0x11d/0x1550 net/bridge/br_device.c:43 #10: (rcu_read_lock_bh){....}, at: [<00000000e1f5f6d5>] __dev_queue_xmit+0x2fe/0x2fc0 net/core/dev.c:3491 stack backtrace: CPU: 1 PID: 9014 Comm: syz-executor7 Not tainted 4.16.0-rc6+ #280 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:3573 [inline] sch_direct_xmit+0x361/0x1140 net/sched/sch_generic.c:325 qdisc_restart net/sched/sch_generic.c:393 [inline] __qdisc_run+0x57d/0x18e0 net/sched/sch_generic.c:401 __dev_xmit_skb net/core/dev.c:3217 [inline] __dev_queue_xmit+0xb8b/0x2fc0 net/core/dev.c:3525 dev_queue_xmit+0x17/0x20 net/core/dev.c:3590 br_dev_queue_push_xmit+0x196/0x5a0 net/bridge/br_forward.c:55 NF_HOOK include/linux/netfilter.h:288 [inline] br_forward_finish+0xc8/0x530 net/bridge/br_forward.c:67 NF_HOOK include/linux/netfilter.h:288 [inline] __br_forward+0x533/0xc80 net/bridge/br_forward.c:112 br_flood+0x665/0x770 net/bridge/br_forward.c:225 br_dev_xmit+0xfbe/0x1550 net/bridge/br_device.c:103 __netdev_start_xmit include/linux/netdevice.h:4078 [inline] netdev_start_xmit include/linux/netdevice.h:4087 [inline] xmit_one net/core/dev.c:3026 [inline] dev_hard_start_xmit+0x24e/0xac0 net/core/dev.c:3042 __dev_queue_xmit+0x26bf/0x2fc0 net/core/dev.c:3557 dev_queue_xmit+0x17/0x20 net/core/dev.c:3590 neigh_hh_output include/net/neighbour.h:472 [inline] neigh_output include/net/neighbour.h:480 [inline] ip_finish_output2+0xf4d/0x1550 net/ipv4/ip_output.c:229 ip_do_fragment+0xc66/0x26d0 net/ipv4/ip_output.c:810 ip_fragment.constprop.47+0x145/0x200 net/ipv4/ip_output.c:546 ip_finish_output+0x698/0xd60 net/ipv4/ip_output.c:315 NF_HOOK_COND include/linux/netfilter.h:277 [inline] ip_mc_output+0x271/0x1350 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:444 [inline] ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124 iptunnel_xmit+0x556/0x810 net/ipv4/ip_tunnel_core.c:91 ip_tunnel_xmit+0x177b/0x3550 net/ipv4/ip_tunnel.c:768 __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:4078 [inline] netdev_start_xmit include/linux/netdevice.h:4087 [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/0x18e0 net/sched/sch_generic.c:401 __dev_xmit_skb net/core/dev.c:3217 [inline] __dev_queue_xmit+0xb8b/0x2fc0 net/core/dev.c:3525 dev_queue_xmit+0x17/0x20 net/core/dev.c:3590 br_dev_queue_push_xmit+0x196/0x5a0 net/bridge/br_forward.c:55 NF_HOOK include/linux/netfilter.h:288 [inline] br_forward_finish+0xc8/0x530 net/bridge/br_forward.c:67 NF_HOOK include/linux/netfilter.h:288 [inline] __br_forward+0x533/0xc80 net/bridge/br_forward.c:112 br_flood+0x665/0x770 net/bridge/br_forward.c:225 br_dev_xmit+0xfbe/0x1550 net/bridge/br_device.c:103 __netdev_start_xmit include/linux/netdevice.h:4078 [inline] netdev_start_xmit include/linux/netdevice.h:4087 [inline] xmit_one net/core/dev.c:3026 [inline] dev_hard_start_xmit+0x24e/0xac0 net/core/dev.c:3042 __dev_queue_xmit+0x26bf/0x2fc0 net/core/dev.c:3557 dev_queue_xmit+0x17/0x20 net/core/dev.c:3590 neigh_resolve_output+0x5e2/0xa00 net/core/neighbour.c:1350 neigh_output include/net/neighbour.h:482 [inline] ip_finish_output2+0x91a/0x1550 net/ipv4/ip_output.c:229 ip_do_fragment+0xc66/0x26d0 net/ipv4/ip_output.c:810 ip_fragment.constprop.47+0x145/0x200 net/ipv4/ip_output.c:546 ip_finish_output+0x698/0xd60 net/ipv4/ip_output.c:315 NF_HOOK_COND include/linux/netfilter.h:277 [inline] ip_mc_output+0x271/0x1350 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:444 [inline] ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124 iptunnel_xmit+0x556/0x810 net/ipv4/ip_tunnel_core.c:91 ip_tunnel_xmit+0x177b/0x3550 net/ipv4/ip_tunnel.c:768 ipip_tunnel_xmit+0x214/0x270 net/ipv4/ipip.c:308 __netdev_start_xmit include/linux/netdevice.h:4078 [inline] netdev_start_xmit include/linux/netdevice.h:4087 [inline] xmit_one net/core/dev.c:3026 [inline] dev_hard_start_xmit+0x24e/0xac0 net/core/dev.c:3042 __dev_queue_xmit+0x26bf/0x2fc0 net/core/dev.c:3557 dev_queue_xmit+0x17/0x20 net/core/dev.c:3590 neigh_direct_output+0x15/0x20 net/core/neighbour.c:1390 neigh_output include/net/neighbour.h:482 [inline] ip_finish_output2+0x91a/0x1550 net/ipv4/ip_output.c:229 ip_do_fragment+0x1f4e/0x26d0 net/ipv4/ip_output.c:675 ip_fragment.constprop.47+0x145/0x200 net/ipv4/ip_output.c:546 ip_finish_output+0x698/0xd60 net/ipv4/ip_output.c:315 NF_HOOK_COND include/linux/netfilter.h:277 [inline] ip_mc_output+0x271/0x1350 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:444 [inline] ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124 ip_send_skb+0x3c/0xc0 net/ipv4/ip_output.c:1414 udp_send_skb+0x666/0xc30 net/ipv4/udp.c:803 udp_sendmsg+0xba0/0x2f70 net/ipv4/udp.c:1038 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xca/0x110 net/socket.c:639 SYSC_sendto+0x361/0x5c0 net/socket.c:1748 SyS_sendto+0x40/0x50 net/socket.c:1716 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x454239 RSP: 002b:00007f0911c5ec68 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f0911c5f6d4 RCX: 0000000000454239 RDX: 000000000000fdc7 RSI: 0000000020762fff RDI: 0000000000000013 RBP: 000000000072bf58 R08: 000000002057bff0 R09: 0000000000000010 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000004cf R14: 00000000006f8408 R15: 0000000000000001