============================================ WARNING: possible recursive locking detected 5.14.0-syzkaller #0 Not tainted -------------------------------------------- syz-executor.2/16976 is trying to acquire lock: ffff88802b081398 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] ffff88802b081398 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4405 [inline] ffff88802b081398 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x30f/0xbc0 net/sched/sch_generic.c:340 but task is already holding lock: ffff88807e8a9098 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] ffff88807e8a9098 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4405 [inline] ffff88807e8a9098 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x30f/0xbc0 net/sched/sch_generic.c:340 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 12 locks held by syz-executor.2/16976: #0: ffffffff8b97fc60 (rcu_read_lock){....}-{1:2}, at: l3mdev_l3_out include/net/l3mdev.h:198 [inline] #0: ffffffff8b97fc60 (rcu_read_lock){....}-{1:2}, at: l3mdev_ip6_out include/net/l3mdev.h:219 [inline] #0: ffffffff8b97fc60 (rcu_read_lock){....}-{1:2}, at: rawv6_send_hdrinc net/ipv6/raw.c:677 [inline] #0: ffffffff8b97fc60 (rcu_read_lock){....}-{1:2}, at: rawv6_sendmsg+0x1f55/0x3a20 net/ipv6/raw.c:944 #1: ffffffff8b97fc00 (rcu_read_lock_bh){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:95 [inline] #1: ffffffff8b97fc00 (rcu_read_lock_bh){....}-{1:2}, at: ip6_finish_output2+0x2ad/0x1500 net/ipv6/ip6_output.c:112 #2: ffffffff8b97fc00 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1da/0x3710 net/core/dev.c:4136 #3: ffff888078641258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline] #3: ffff888078641258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline] #3: ffff888078641258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3790 [inline] #3: ffff888078641258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x125c/0x3710 net/core/dev.c:4170 #4: ffff88807e8a9098 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] #4: ffff88807e8a9098 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4405 [inline] #4: ffff88807e8a9098 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x30f/0xbc0 net/sched/sch_generic.c:340 #5: ffff88807b5887a0 (k-slock-AF_INET6){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline] #5: ffff88807b5887a0 (k-slock-AF_INET6){+.-.}-{2:2}, at: icmpv6_xmit_lock net/ipv6/icmp.c:117 [inline] #5: ffff88807b5887a0 (k-slock-AF_INET6){+.-.}-{2:2}, at: icmp6_send+0xe49/0x2670 net/ipv6/icmp.c:547 #6: ffffffff8b97fc60 (rcu_read_lock){....}-{1:2}, at: icmp6_send+0x1429/0x2670 net/ipv6/icmp.c:607 #7: ffffffff8b97fc00 (rcu_read_lock_bh){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:95 [inline] #7: ffffffff8b97fc00 (rcu_read_lock_bh){....}-{1:2}, at: ip6_finish_output2+0x2ad/0x1500 net/ipv6/ip6_output.c:112 #8: ffffffff8b97fc60 (rcu_read_lock){....}-{1:2}, at: ip6_nd_hdr net/ipv6/ndisc.c:466 [inline] #8: ffffffff8b97fc60 (rcu_read_lock){....}-{1:2}, at: ndisc_send_skb+0x84b/0x17f0 net/ipv6/ndisc.c:502 #9: ffffffff8b97fc00 (rcu_read_lock_bh){....}-{1:2}, at: lwtunnel_xmit_redirect include/net/lwtunnel.h:95 [inline] #9: ffffffff8b97fc00 (rcu_read_lock_bh){....}-{1:2}, at: ip6_finish_output2+0x2ad/0x1500 net/ipv6/ip6_output.c:112 #10: ffffffff8b97fc00 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1da/0x3710 net/core/dev.c:4136 #11: ffff88802b7de258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline] #11: ffff88802b7de258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline] #11: ffff88802b7de258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3790 [inline] #11: ffff88802b7de258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x125c/0x3710 net/core/dev.c:4170 stack backtrace: CPU: 1 PID: 16976 Comm: syz-executor.2 Not tainted 5.14.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 print_deadlock_bug kernel/locking/lockdep.c:2944 [inline] check_deadlock kernel/locking/lockdep.c:2987 [inline] validate_chain kernel/locking/lockdep.c:3776 [inline] __lock_acquire.cold+0x149/0x3ab kernel/locking/lockdep.c:5015 lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:363 [inline] __netif_tx_lock include/linux/netdevice.h:4405 [inline] sch_direct_xmit+0x30f/0xbc0 net/sched/sch_generic.c:340 __dev_xmit_skb net/core/dev.c:3803 [inline] __dev_queue_xmit+0x14c3/0x3710 net/core/dev.c:4170 neigh_resolve_output net/core/neighbour.c:1492 [inline] neigh_resolve_output+0x50e/0x820 net/core/neighbour.c:1472 neigh_output include/net/neighbour.h:510 [inline] ip6_finish_output2+0x717/0x1500 net/ipv6/ip6_output.c:126 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline] __ip6_finish_output+0x4c1/0x1050 net/ipv6/ip6_output.c:170 ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224 dst_output include/net/dst.h:450 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] ndisc_send_skb+0xa99/0x17f0 net/ipv6/ndisc.c:508 ndisc_send_ns+0x3a9/0x840 net/ipv6/ndisc.c:650 ndisc_solicit+0x2cd/0x4f0 net/ipv6/ndisc.c:742 neigh_probe+0xc2/0x110 net/core/neighbour.c:1011 __neigh_event_send+0x37d/0x1570 net/core/neighbour.c:1172 neigh_event_send include/net/neighbour.h:444 [inline] neigh_resolve_output+0x538/0x820 net/core/neighbour.c:1476 neigh_output include/net/neighbour.h:510 [inline] ip6_finish_output2+0x717/0x1500 net/ipv6/ip6_output.c:126 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline] __ip6_finish_output+0x4c1/0x1050 net/ipv6/ip6_output.c:170 ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224 dst_output include/net/dst.h:450 [inline] ip6_local_out+0xaf/0x1a0 net/ipv6/output_core.c:161 ip6_send_skb+0xb7/0x340 net/ipv6/ip6_output.c:1911 ip6_push_pending_frames+0xdd/0x100 net/ipv6/ip6_output.c:1931 icmpv6_push_pending_frames+0x294/0x470 net/ipv6/icmp.c:310 icmp6_send+0x1d58/0x2670 net/ipv6/icmp.c:626 __icmpv6_send include/linux/icmpv6.h:28 [inline] icmpv6_send include/linux/icmpv6.h:49 [inline] ip6_link_failure+0x2d/0x520 net/ipv6/route.c:2790 dst_link_failure include/net/dst.h:429 [inline] ip_tunnel_xmit+0x160c/0x2b60 net/ipv4/ip_tunnel.c:816 erspan_xmit+0x7e2/0x29c0 net/ipv4/ip_gre.c:712 __netdev_start_xmit include/linux/netdevice.h:4988 [inline] netdev_start_xmit include/linux/netdevice.h:5002 [inline] xmit_one net/core/dev.c:3576 [inline] dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3592 sch_direct_xmit+0x19f/0xbc0 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3803 [inline] __dev_queue_xmit+0x14c3/0x3710 net/core/dev.c:4170 neigh_resolve_output net/core/neighbour.c:1492 [inline] neigh_resolve_output+0x50e/0x820 net/core/neighbour.c:1472 neigh_output include/net/neighbour.h:510 [inline] ip6_finish_output2+0x717/0x1500 net/ipv6/ip6_output.c:126 __ip6_finish_output net/ipv6/ip6_output.c:191 [inline] __ip6_finish_output+0x4c1/0x1050 net/ipv6/ip6_output.c:170 ip6_finish_output+0x32/0x200 net/ipv6/ip6_output.c:201 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip6_output+0x1e4/0x530 net/ipv6/ip6_output.c:224 dst_output include/net/dst.h:450 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] rawv6_send_hdrinc net/ipv6/raw.c:687 [inline] rawv6_sendmsg+0x2183/0x3a20 net/ipv6/raw.c:944 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:821 sock_sendmsg_nosec net/socket.c:704 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:724 ____sys_sendmsg+0x331/0x810 net/socket.c:2409 ___sys_sendmsg+0xf3/0x170 net/socket.c:2463 __sys_sendmmsg+0x195/0x470 net/socket.c:2549 __do_sys_sendmmsg net/socket.c:2578 [inline] __se_sys_sendmmsg net/socket.c:2575 [inline] __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2575 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665f9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8a42394188 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665f9 RDX: 0000000000000001 RSI: 0000000020000280 RDI: 0000000000000003 RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007fff28c81bdf R14: 00007f8a42394300 R15: 0000000000022000 syz-executor.2 (16976) used greatest stack depth: 21528 bytes left