====================================================== WARNING: possible circular locking dependency detected 6.8.0-syzkaller-05204-g237bb5f7f7f5 #0 Not tainted ------------------------------------------------------ syz-executor.2/7445 is trying to acquire lock: ffff888021886218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff888021886218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3790 [inline] ffff888021886218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2){+...}-{2:2}, at: __dev_queue_xmit+0x20af/0x3b10 net/core/dev.c:4301 but task is already holding lock: ffff88807c3ca8d8 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88807c3ca8d8 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4371 [inline] ffff88807c3ca8d8 (&qdisc_xmit_lock_key#2){+.-.}-{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#2){+.-.}-{2:2}: lock_acquire+0x1e4/0x530 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:4371 [inline] sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:341 __dev_xmit_skb net/core/dev.c:3760 [inline] __dev_queue_xmit+0x1912/0x3b10 net/core/dev.c:4301 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:3254 [inline] process_scheduled_works+0xa00/0x1770 kernel/workqueue.c:3335 worker_thread+0x86d/0xd70 kernel/workqueue.c:3416 kthread+0x2f0/0x390 kernel/kthread.c:388 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243 -> #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+0x1e4/0x530 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:3790 [inline] __dev_queue_xmit+0x20af/0x3b10 net/core/dev.c:4301 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:1075 [inline] __neigh_event_send+0xe9a/0x1550 net/core/neighbour.c:1242 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:1547 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+0x162b/0x2940 net/ipv4/ip_tunnel.c:863 erspan_xmit+0xa18/0x1500 net/ipv4/ip_gre.c:720 __netdev_start_xmit include/linux/netdevice.h:4903 [inline] netdev_start_xmit include/linux/netdevice.h:4917 [inline] xmit_one net/core/dev.c:3531 [inline] dev_hard_start_xmit+0x26a/0x790 net/core/dev.c:3547 sch_direct_xmit+0x2b6/0x5f0 net/sched/sch_generic.c:343 qdisc_restart net/sched/sch_generic.c:408 [inline] __qdisc_run+0xbed/0x2150 net/sched/sch_generic.c:416 __dev_xmit_skb net/core/dev.c:3823 [inline] __dev_queue_xmit+0xfc6/0x3b10 net/core/dev.c:4301 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+0xc0b/0x1710 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 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x6d/0x75 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&qdisc_xmit_lock_key#2); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2); lock(&qdisc_xmit_lock_key#2); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#2); *** DEADLOCK *** 10 locks held by syz-executor.2/7445: #0: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline] #0: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline] #0: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rawv6_send_hdrinc+0xa89/0x1710 net/ipv6/raw.c:659 #1: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline] #1: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline] #1: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x712/0x1670 net/ipv6/ip6_output.c:122 #2: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #2: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline] #2: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2c4/0x3b10 net/core/dev.c:4260 #3: ffff88807c3ca8d8 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #3: ffff88807c3ca8d8 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4371 [inline] #3: ffff88807c3ca8d8 (&qdisc_xmit_lock_key#2){+.-.}-{2:2}, at: sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:341 #4: ffff8880299b81d8 (k-slock-AF_INET6){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #4: ffff8880299b81d8 (k-slock-AF_INET6){+.-.}-{2:2}, at: icmpv6_xmit_lock net/ipv6/icmp.c:108 [inline] #4: ffff8880299b81d8 (k-slock-AF_INET6){+.-.}-{2:2}, at: icmp6_send+0xc45/0x2070 net/ipv6/icmp.c:545 #5: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #5: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: icmp6_send+0xba4/0x2070 net/ipv6/icmp.c:537 #6: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline] #6: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline] #6: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x712/0x1670 net/ipv6/ip6_output.c:122 #7: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline] #7: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline] #7: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: ip6_nd_hdr net/ipv6/ndisc.c:452 [inline] #7: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: ndisc_send_skb+0x572/0x1380 net/ipv6/ndisc.c:503 #8: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline] #8: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline] #8: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: ip6_finish_output2+0x712/0x1670 net/ipv6/ip6_output.c:122 #9: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #9: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline] #9: ffffffff8e131980 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2c4/0x3b10 net/core/dev.c:4260 stack backtrace: CPU: 0 PID: 7445 Comm: syz-executor.2 Not tainted 6.8.0-syzkaller-05204-g237bb5f7f7f5 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106 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+0x1e4/0x530 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:3790 [inline] __dev_queue_xmit+0x20af/0x3b10 net/core/dev.c:4301 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:1075 [inline] __neigh_event_send+0xe9a/0x1550 net/core/neighbour.c:1242 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:1547 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+0x162b/0x2940 net/ipv4/ip_tunnel.c:863 erspan_xmit+0xa18/0x1500 net/ipv4/ip_gre.c:720 __netdev_start_xmit include/linux/netdevice.h:4903 [inline] netdev_start_xmit include/linux/netdevice.h:4917 [inline] xmit_one net/core/dev.c:3531 [inline] dev_hard_start_xmit+0x26a/0x790 net/core/dev.c:3547 sch_direct_xmit+0x2b6/0x5f0 net/sched/sch_generic.c:343 qdisc_restart net/sched/sch_generic.c:408 [inline] __qdisc_run+0xbed/0x2150 net/sched/sch_generic.c:416 __dev_xmit_skb net/core/dev.c:3823 [inline] __dev_queue_xmit+0xfc6/0x3b10 net/core/dev.c:4301 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+0xc0b/0x1710 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 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x6d/0x75 RIP: 0033:0x7f03dde7dda9 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:00007f03debe70c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f03ddfabf80 RCX: 00007f03dde7dda9 RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000003 RBP: 00007f03ddeca47a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007f03ddfabf80 R15: 00007ffcc6601fd8 syz-executor.2 (7445) used greatest stack depth: 18032 bytes left