============================================ WARNING: possible recursive locking detected 5.1.0-rc2+ #112 Not tainted -------------------------------------------- syz-executor.0/13941 is trying to acquire lock: 000000009c1e85f2 (_xmit_ETHER#2){+.-.}, at: spin_lock include/linux/spinlock.h:329 [inline] 000000009c1e85f2 (_xmit_ETHER#2){+.-.}, at: __netif_tx_lock include/linux/netdevice.h:3893 [inline] 000000009c1e85f2 (_xmit_ETHER#2){+.-.}, at: __dev_queue_xmit+0x2b65/0x36b0 net/core/dev.c:3867 but task is already holding lock: 000000000ad63340 (_xmit_ETHER#2){+.-.}, at: spin_lock include/linux/spinlock.h:329 [inline] 000000000ad63340 (_xmit_ETHER#2){+.-.}, at: __netif_tx_lock include/linux/netdevice.h:3893 [inline] 000000000ad63340 (_xmit_ETHER#2){+.-.}, at: sch_direct_xmit+0x2de/0xf70 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 7 locks held by syz-executor.0/13941: #0: 000000007091b59b (rcu_read_lock_bh){....}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #0: 000000007091b59b (rcu_read_lock_bh){....}, at: ip_finish_output2+0x2af/0x1740 net/ipv4/ip_output.c:213 #1: 000000007091b59b (rcu_read_lock_bh){....}, at: __dev_queue_xmit+0x20a/0x36b0 net/core/dev.c:3805 #2: 00000000aa7d63d7 (&(&sch->seqlock)->rlock){+...}, at: spin_trylock include/linux/spinlock.h:339 [inline] #2: 00000000aa7d63d7 (&(&sch->seqlock)->rlock){+...}, at: qdisc_run_begin include/net/sch_generic.h:159 [inline] #2: 00000000aa7d63d7 (&(&sch->seqlock)->rlock){+...}, at: __dev_xmit_skb net/core/dev.c:3472 [inline] #2: 00000000aa7d63d7 (&(&sch->seqlock)->rlock){+...}, at: __dev_queue_xmit+0x251d/0x36b0 net/core/dev.c:3839 #3: 00000000a23aaf2c (dev->qdisc_running_key ?: &qdisc_running_key){+...}, at: dev_queue_xmit+0x18/0x20 net/core/dev.c:3904 #4: 000000000ad63340 (_xmit_ETHER#2){+.-.}, at: spin_lock include/linux/spinlock.h:329 [inline] #4: 000000000ad63340 (_xmit_ETHER#2){+.-.}, at: __netif_tx_lock include/linux/netdevice.h:3893 [inline] #4: 000000000ad63340 (_xmit_ETHER#2){+.-.}, at: sch_direct_xmit+0x2de/0xf70 net/sched/sch_generic.c:325 #5: 000000007091b59b (rcu_read_lock_bh){....}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #5: 000000007091b59b (rcu_read_lock_bh){....}, at: ip_finish_output2+0x2af/0x1740 net/ipv4/ip_output.c:213 #6: 000000007091b59b (rcu_read_lock_bh){....}, at: __dev_queue_xmit+0x20a/0x36b0 net/core/dev.c:3805 stack backtrace: CPU: 1 PID: 13941 Comm: syz-executor.0 Not tainted 5.1.0-rc2+ #112 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_deadlock_bug kernel/locking/lockdep.c:2100 [inline] check_deadlock kernel/locking/lockdep.c:2144 [inline] validate_chain kernel/locking/lockdep.c:2698 [inline] __lock_acquire.cold+0x233/0x50d kernel/locking/lockdep.c:3701 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4211 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] __netif_tx_lock include/linux/netdevice.h:3893 [inline] __dev_queue_xmit+0x2b65/0x36b0 net/core/dev.c:3867 dev_queue_xmit+0x18/0x20 net/core/dev.c:3904 neigh_resolve_output net/core/neighbour.c:1487 [inline] neigh_resolve_output+0x5a7/0x970 net/core/neighbour.c:1467 neigh_output include/net/neighbour.h:508 [inline] ip_finish_output2+0x949/0x1740 net/ipv4/ip_output.c:229 ip_finish_output+0x73c/0xd50 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip_mc_output+0x292/0xf70 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:433 [inline] ip_local_out+0xc4/0x1b0 net/ipv4/ip_output.c:124 iptunnel_xmit+0x58e/0x980 net/ipv4/ip_tunnel_core.c:91 ip_tunnel_xmit+0x1038/0x2bfa net/ipv4/ip_tunnel.c:831 __gre_xmit+0x5e9/0x9a0 net/ipv4/ip_gre.c:444 erspan_xmit+0x912/0x28b0 net/ipv4/ip_gre.c:679 __netdev_start_xmit include/linux/netdevice.h:4409 [inline] netdev_start_xmit include/linux/netdevice.h:4418 [inline] xmit_one net/core/dev.c:3278 [inline] dev_hard_start_xmit+0x1b2/0x980 net/core/dev.c:3294 sch_direct_xmit+0x370/0xf70 net/sched/sch_generic.c:327 __dev_xmit_skb net/core/dev.c:3475 [inline] __dev_queue_xmit+0x282d/0x36b0 net/core/dev.c:3839 dev_queue_xmit+0x18/0x20 net/core/dev.c:3904 neigh_resolve_output net/core/neighbour.c:1487 [inline] neigh_resolve_output+0x5a7/0x970 net/core/neighbour.c:1467 neigh_output include/net/neighbour.h:508 [inline] ip_finish_output2+0x949/0x1740 net/ipv4/ip_output.c:229 ip_finish_output+0x73c/0xd50 net/ipv4/ip_output.c:317 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip_mc_output+0x292/0xf70 net/ipv4/ip_output.c:390 dst_output include/net/dst.h:433 [inline] ip_local_out+0xc4/0x1b0 net/ipv4/ip_output.c:124 ip_send_skb+0x42/0xf0 net/ipv4/ip_output.c:1465 udp_send_skb.isra.0+0x6b2/0x1180 net/ipv4/udp.c:901 udp_sendmsg+0x1dfd/0x2820 net/ipv4/udp.c:1188 inet_sendmsg+0x147/0x5e0 net/ipv4/af_inet.c:802 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xdd/0x130 net/socket.c:661 ___sys_sendmsg+0x3e2/0x930 net/socket.c:2260 __sys_sendmmsg+0x1bf/0x4d0 net/socket.c:2355 __do_sys_sendmmsg net/socket.c:2384 [inline] __se_sys_sendmmsg net/socket.c:2381 [inline] __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2381 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x458209 Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f1154031c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000458209 RDX: 04000000000001a8 RSI: 0000000020007fc0 RDI: 0000000000000003 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f11540326d4 R13: 00000000004c5190 R14: 00000000004d92e0 R15: 00000000ffffffff