============================================ WARNING: possible recursive locking detected 5.10.0-syzkaller #0 Not tainted -------------------------------------------- syz-executor.4/5660 is trying to acquire lock: ffff88805e903398 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] ffff88805e903398 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4214 [inline] ffff88805e903398 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x256/0xbd0 net/sched/sch_generic.c:311 but task is already holding lock: ffff888021c6a498 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] ffff888021c6a498 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4214 [inline] ffff888021c6a498 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x256/0xbd0 net/sched/sch_generic.c:311 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 9 locks held by syz-executor.4/5660: #0: ffffffff8b339fc0 (rcu_read_lock_bh){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] (rcu_read_lock_bh){....}-{1:2}, at: ip_finish_output2+0x290/0x2120 net/ipv4/ip_output.c:216 #1: ffffffff8b339fc0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1d7/0x2dd0 net/core/dev.c:4067 #2: ffff88801a113258 (&sch->seqlock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:364 [inline] #2: ffff88801a113258 (&sch->seqlock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:162 [inline] #2: ffff88801a113258 (&sch->seqlock){+...}-{2:2}, at: qdisc_run include/net/pkt_sched.h:130 [inline] #2: ffff88801a113258 (&sch->seqlock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3747 [inline] #2: ffff88801a113258 (&sch->seqlock){+...}-{2:2}, at: __dev_queue_xmit+0x1343/0x2dd0 net/core/dev.c:4101 #3: ffff88801a113148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: neigh_resolve_output net/core/neighbour.c:1491 [inline] #3: ffff88801a113148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: neigh_resolve_output+0x4d8/0x7e0 net/core/neighbour.c:1471 #4: ffff888021c6a498 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline] #4: ffff888021c6a498 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4214 [inline] #4: ffff888021c6a498 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x256/0xbd0 net/sched/sch_generic.c:311 #5: ffffffff8b339fc0 (rcu_read_lock_bh){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:92 [inline] #5: ffffffff8b339fc0 (rcu_read_lock_bh){....}-{1:2}, at: ip_finish_output2+0x290/0x2120 net/ipv4/ip_output.c:216 #6: ffffffff8b339fc0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1d7/0x2dd0 net/core/dev.c:4067 #7: ffff8880652d6258 (&sch->seqlock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:364 [inline] #7: ffff8880652d6258 (&sch->seqlock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:162 [inline] #7: ffff8880652d6258 (&sch->seqlock){+...}-{2:2}, at: qdisc_run include/net/pkt_sched.h:130 [inline] #7: ffff8880652d6258 (&sch->seqlock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3747 [inline] #7: ffff8880652d6258 (&sch->seqlock){+...}-{2:2}, at: __dev_queue_xmit+0x1343/0x2dd0 net/core/dev.c:4101 #8: ffff8880652d6148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: neigh_hh_output include/net/neighbour.h:499 [inline] #8: ffff8880652d6148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: neigh_output include/net/neighbour.h:508 [inline] #8: ffff8880652d6148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: ip_finish_output2+0xe95/0x2120 net/ipv4/ip_output.c:230 stack backtrace: CPU: 1 PID: 5660 Comm: syz-executor.4 Not tainted 5.10.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 print_deadlock_bug kernel/locking/lockdep.c:2761 [inline] check_deadlock kernel/locking/lockdep.c:2804 [inline] validate_chain kernel/locking/lockdep.c:3595 [inline] __lock_acquire.cold+0x15e/0x3b0 kernel/locking/lockdep.c:4832 lock_acquire kernel/locking/lockdep.c:5437 [inline] lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151 spin_lock include/linux/spinlock.h:354 [inline] __netif_tx_lock include/linux/netdevice.h:4214 [inline] sch_direct_xmit+0x256/0xbd0 net/sched/sch_generic.c:311 qdisc_restart net/sched/sch_generic.c:376 [inline] __qdisc_run+0x4ba/0x15e0 net/sched/sch_generic.c:384 qdisc_run include/net/pkt_sched.h:136 [inline] qdisc_run include/net/pkt_sched.h:128 [inline] __dev_xmit_skb net/core/dev.c:3747 [inline] __dev_queue_xmit+0x1489/0x2dd0 net/core/dev.c:4101 neigh_hh_output include/net/neighbour.h:499 [inline] neigh_output include/net/neighbour.h:508 [inline] ip_finish_output2+0xe95/0x2120 net/ipv4/ip_output.c:230 __ip_finish_output net/ipv4/ip_output.c:308 [inline] __ip_finish_output+0x7cf/0xd10 net/ipv4/ip_output.c:290 ip_finish_output+0x34/0x1f0 net/ipv4/ip_output.c:318 NF_HOOK_COND include/linux/netfilter.h:290 [inline] ip_mc_output+0x212/0x700 net/ipv4/ip_output.c:417 dst_output include/net/dst.h:441 [inline] ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:126 iptunnel_xmit+0x5a3/0x9c0 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x1b78/0x2b00 net/ipv4/ip_tunnel.c:807 erspan_xmit+0x1109/0x2760 net/ipv4/ip_gre.c:702 __netdev_start_xmit include/linux/netdevice.h:4775 [inline] netdev_start_xmit include/linux/netdevice.h:4789 [inline] xmit_one net/core/dev.c:3556 [inline] dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3572 sch_direct_xmit+0x2e1/0xbd0 net/sched/sch_generic.c:313 qdisc_restart net/sched/sch_generic.c:376 [inline] __qdisc_run+0x4ba/0x15e0 net/sched/sch_generic.c:384 qdisc_run include/net/pkt_sched.h:136 [inline] qdisc_run include/net/pkt_sched.h:128 [inline] __dev_xmit_skb net/core/dev.c:3747 [inline] __dev_queue_xmit+0x1489/0x2dd0 net/core/dev.c:4101 neigh_resolve_output net/core/neighbour.c:1491 [inline] neigh_resolve_output+0x4d8/0x7e0 net/core/neighbour.c:1471 neigh_output include/net/neighbour.h:510 [inline] ip_finish_output2+0x81c/0x2120 net/ipv4/ip_output.c:230 __ip_finish_output net/ipv4/ip_output.c:308 [inline] __ip_finish_output+0x7cf/0xd10 net/ipv4/ip_output.c:290 ip_finish_output+0x34/0x1f0 net/ipv4/ip_output.c:318 NF_HOOK_COND include/linux/netfilter.h:290 [inline] ip_mc_output+0x212/0x700 net/ipv4/ip_output.c:417 dst_output include/net/dst.h:441 [inline] ip_local_out net/ipv4/ip_output.c:126 [inline] ip_send_skb+0xd4/0x260 net/ipv4/ip_output.c:1568 udp_send_skb+0x6cd/0x11a0 net/ipv4/udp.c:947 udp_sendmsg+0x1c76/0x2720 net/ipv4/udp.c:1234 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:817 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x331/0x810 net/socket.c:2336 ___sys_sendmsg+0xf3/0x170 net/socket.c:2390 __sys_sendmmsg+0x195/0x470 net/socket.c:2480 __do_sys_sendmmsg net/socket.c:2509 [inline] __se_sys_sendmmsg net/socket.c:2506 [inline] __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2506 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45e229 Code: 0d b4 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 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007feae984cc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045e229 RDX: 000000000800001d RSI: 0000000020007fc0 RDI: 0000000000000004 RBP: 000000000119c070 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119c034 R13: 00007fffbbeff55f R14: 00007feae984d9c0 R15: 000000000119c034