======================================================
WARNING: possible circular locking dependency detected
6.9.0-syzkaller-08284-gea5f6ad9ad96 #0 Not tainted
------------------------------------------------------
syz-executor.3/17878 is trying to acquire lock:
ffff888029e5e218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff888029e5e218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3841 [inline]
ffff888029e5e218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x22f5/0x3d30 net/core/dev.c:4359

but task is already holding lock:
ffff88802f35e8d8 (&qdisc_xmit_lock_key#3){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff88802f35e8d8 (&qdisc_xmit_lock_key#3){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4347 [inline]
ffff88802f35e8d8 (&qdisc_xmit_lock_key#3){+.-.}-{2:2}, at: sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:341

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&qdisc_xmit_lock_key#3){+.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       spin_lock include/linux/spinlock.h:351 [inline]
       __netif_tx_lock include/linux/netdevice.h:4347 [inline]
       sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:341
       __dev_xmit_skb net/core/dev.c:3807 [inline]
       __dev_queue_xmit+0x1a24/0x3d30 net/core/dev.c:4359
       neigh_output include/net/neighbour.h:542 [inline]
       ip6_finish_output2+0xff8/0x1670 net/ipv6/ip6_output.c:137
       ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:222
       NF_HOOK+0x9e/0x430 include/linux/netfilter.h:314
       mld_sendpack+0x838/0xda0 net/ipv6/mcast.c:1818
       mld_send_cr net/ipv6/mcast.c:2119 [inline]
       mld_ifc_work+0x7d6/0xd90 net/ipv6/mcast.c:2650
       process_one_work kernel/workqueue.c:3231 [inline]
       process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
       worker_thread+0x86d/0xd70 kernel/workqueue.c:3393
       kthread+0x2f0/0x390 kernel/kthread.c:389
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+.-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       spin_lock include/linux/spinlock.h:351 [inline]
       __dev_xmit_skb net/core/dev.c:3841 [inline]
       __dev_queue_xmit+0x22f5/0x3d30 net/core/dev.c:4359
       neigh_output include/net/neighbour.h:542 [inline]
       ip6_finish_output2+0xff8/0x1670 net/ipv6/ip6_output.c:137
       ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:222
       NF_HOOK include/linux/netfilter.h:314 [inline]
       ndisc_send_skb+0xab0/0x1380 net/ipv6/ndisc.c:509
       ndisc_solicit+0x493/0x6a0
       neigh_probe net/core/neighbour.c:1077 [inline]
       __neigh_event_send+0xec8/0x15a0 net/core/neighbour.c:1244
       neigh_event_send_probe include/net/neighbour.h:466 [inline]
       neigh_event_send include/net/neighbour.h:472 [inline]
       neigh_resolve_output+0x1b5/0x740 net/core/neighbour.c:1549
       neigh_output include/net/neighbour.h:542 [inline]
       ip6_finish_output2+0xff8/0x1670 net/ipv6/ip6_output.c:137
       ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:222
       ip6_send_skb+0x112/0x230 net/ipv6/ip6_output.c:1955
       icmp6_send+0x15fc/0x2070 net/ipv6/icmp.c:624
       __icmpv6_send include/linux/icmpv6.h:28 [inline]
       icmpv6_send include/linux/icmpv6.h:49 [inline]
       ip6_link_failure+0x3c/0x4f0 net/ipv6/route.c:2797
       ip_tunnel_xmit+0x164f/0x2940 net/ipv4/ip_tunnel.c:863
       __gre_xmit+0x1cf/0x260 net/ipv4/ip_gre.c:483
       erspan_xmit+0xaba/0x1310 net/ipv4/ip_gre.c:742
       __netdev_start_xmit include/linux/netdevice.h:4882 [inline]
       netdev_start_xmit include/linux/netdevice.h:4896 [inline]
       xmit_one net/core/dev.c:3578 [inline]
       dev_hard_start_xmit+0x27a/0x7e0 net/core/dev.c:3594
       sch_direct_xmit+0x2b6/0x5f0 net/sched/sch_generic.c:343
       qdisc_restart net/sched/sch_generic.c:408 [inline]
       __qdisc_run+0xbfd/0x2170 net/sched/sch_generic.c:416
       qdisc_run+0xda/0x270 include/net/pkt_sched.h:127
       net_tx_action+0x89c/0xa50 net/core/dev.c:5286
       handle_softirqs+0x2d6/0x990 kernel/softirq.c:554
       do_softirq+0x11b/0x1e0 kernel/softirq.c:455
       __local_bh_enable_ip+0x1bb/0x200 kernel/softirq.c:382
       local_bh_enable include/linux/bottom_half.h:33 [inline]
       rcu_read_unlock_bh include/linux/rcupdate.h:851 [inline]
       __dev_queue_xmit+0x16c9/0x3d30 net/core/dev.c:4420
       neigh_output include/net/neighbour.h:542 [inline]
       ip6_finish_output2+0xff8/0x1670 net/ipv6/ip6_output.c:137
       ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:222
       NF_HOOK include/linux/netfilter.h:314 [inline]
       rawv6_send_hdrinc+0xb79/0x1610 net/ipv6/raw.c:661
       rawv6_sendmsg+0x1962/0x23c0 net/ipv6/raw.c:914
       sock_sendmsg_nosec net/socket.c:730 [inline]
       __sock_sendmsg+0x1a6/0x270 net/socket.c:745
       sock_write_iter+0x2dd/0x400 net/socket.c:1160
       call_write_iter include/linux/fs.h:2120 [inline]
       new_sync_write fs/read_write.c:497 [inline]
       vfs_write+0xa2d/0xc50 fs/read_write.c:590
       ksys_write+0x1a0/0x2c0 fs/read_write.c:643
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&qdisc_xmit_lock_key#3);
                               lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2);
                               lock(&qdisc_xmit_lock_key#3);
  lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2);

 *** DEADLOCK ***

10 locks held by syz-executor.3/17878:
 #0: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #0: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #0: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rawv6_send_hdrinc+0x9df/0x1610 net/ipv6/raw.c:659
 #1: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #1: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #1: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x712/0x1670 net/ipv6/ip6_output.c:122
 #2: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #2: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #2: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: net_tx_action+0x708/0xa50 net/core/dev.c:5255
 #3: ffff88802f35e8d8 (&qdisc_xmit_lock_key#3){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #3: ffff88802f35e8d8 (&qdisc_xmit_lock_key#3){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4347 [inline]
 #3: ffff88802f35e8d8 (&qdisc_xmit_lock_key#3){+.-.}-{2:2}, at: sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:341
 #4: ffff88802aca81d8 (k-slock-AF_INET6){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
 #4: ffff88802aca81d8 (k-slock-AF_INET6){+.-.}-{2:2}, at: icmpv6_xmit_lock net/ipv6/icmp.c:108 [inline]
 #4: ffff88802aca81d8 (k-slock-AF_INET6){+.-.}-{2:2}, at: icmp6_send+0xc45/0x2070 net/ipv6/icmp.c:545
 #5: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
 #5: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: icmp6_send+0xba4/0x2070 net/ipv6/icmp.c:537
 #6: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #6: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #6: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x712/0x1670 net/ipv6/ip6_output.c:122
 #7: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #7: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #7: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: ip6_nd_hdr net/ipv6/ndisc.c:452 [inline]
 #7: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: ndisc_send_skb+0x572/0x1380 net/ipv6/ndisc.c:503
 #8: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #8: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
 #8: ffffffff8e334360 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x712/0x1670 net/ipv6/ip6_output.c:122
 #9: ffffffff8e3343c0 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
 #9: ffffffff8e3343c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:833 [inline]
 #9: ffffffff8e3343c0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2d2/0x3d30 net/core/dev.c:4318

stack backtrace:
CPU: 0 PID: 17878 Comm: syz-executor.3 Not tainted 6.9.0-syzkaller-08284-gea5f6ad9ad96 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 __dev_xmit_skb net/core/dev.c:3841 [inline]
 __dev_queue_xmit+0x22f5/0x3d30 net/core/dev.c:4359
 neigh_output include/net/neighbour.h:542 [inline]
 ip6_finish_output2+0xff8/0x1670 net/ipv6/ip6_output.c:137
 ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:222
 NF_HOOK include/linux/netfilter.h:314 [inline]
 ndisc_send_skb+0xab0/0x1380 net/ipv6/ndisc.c:509
 ndisc_solicit+0x493/0x6a0
 neigh_probe net/core/neighbour.c:1077 [inline]
 __neigh_event_send+0xec8/0x15a0 net/core/neighbour.c:1244
 neigh_event_send_probe include/net/neighbour.h:466 [inline]
 neigh_event_send include/net/neighbour.h:472 [inline]
 neigh_resolve_output+0x1b5/0x740 net/core/neighbour.c:1549
 neigh_output include/net/neighbour.h:542 [inline]
 ip6_finish_output2+0xff8/0x1670 net/ipv6/ip6_output.c:137
 ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:222
 ip6_send_skb+0x112/0x230 net/ipv6/ip6_output.c:1955
 icmp6_send+0x15fc/0x2070 net/ipv6/icmp.c:624
 __icmpv6_send include/linux/icmpv6.h:28 [inline]
 icmpv6_send include/linux/icmpv6.h:49 [inline]
 ip6_link_failure+0x3c/0x4f0 net/ipv6/route.c:2797
 ip_tunnel_xmit+0x164f/0x2940 net/ipv4/ip_tunnel.c:863
 __gre_xmit+0x1cf/0x260 net/ipv4/ip_gre.c:483
 erspan_xmit+0xaba/0x1310 net/ipv4/ip_gre.c:742
 __netdev_start_xmit include/linux/netdevice.h:4882 [inline]
 netdev_start_xmit include/linux/netdevice.h:4896 [inline]
 xmit_one net/core/dev.c:3578 [inline]
 dev_hard_start_xmit+0x27a/0x7e0 net/core/dev.c:3594
 sch_direct_xmit+0x2b6/0x5f0 net/sched/sch_generic.c:343
 qdisc_restart net/sched/sch_generic.c:408 [inline]
 __qdisc_run+0xbfd/0x2170 net/sched/sch_generic.c:416
 qdisc_run+0xda/0x270 include/net/pkt_sched.h:127
 net_tx_action+0x89c/0xa50 net/core/dev.c:5286
 handle_softirqs+0x2d6/0x990 kernel/softirq.c:554
 do_softirq+0x11b/0x1e0 kernel/softirq.c:455
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x1bb/0x200 kernel/softirq.c:382
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:851 [inline]
 __dev_queue_xmit+0x16c9/0x3d30 net/core/dev.c:4420
 neigh_output include/net/neighbour.h:542 [inline]
 ip6_finish_output2+0xff8/0x1670 net/ipv6/ip6_output.c:137
 ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:222
 NF_HOOK include/linux/netfilter.h:314 [inline]
 rawv6_send_hdrinc+0xb79/0x1610 net/ipv6/raw.c:661
 rawv6_sendmsg+0x1962/0x23c0 net/ipv6/raw.c:914
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x1a6/0x270 net/socket.c:745
 sock_write_iter+0x2dd/0x400 net/socket.c:1160
 call_write_iter include/linux/fs.h:2120 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xa2d/0xc50 fs/read_write.c:590
 ksys_write+0x1a0/0x2c0 fs/read_write.c:643
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7debe7cee9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7decbfb0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f7debfabf80 RCX: 00007f7debe7cee9
RDX: 0000000000000028 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00007f7debec949e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f7debfabf80 R15: 00007ffdad8405b8
 </TASK>