syzbot


INFO: task hung in register_netdevice_notifier_net (3)

Status: auto-obsoleted due to no activity on 2025/10/01 08:57
Subsystems: net
[Documentation on labels]
First crash: 201d, last: 175d
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in register_netdevice_notifier_net net 1 7 442d 583d 0/29 auto-obsoleted due to no activity on 2025/01/07 03:50
upstream INFO: task hung in register_netdevice_notifier_net (2) kernel 1 1 314d 314d 0/29 auto-obsoleted due to no activity on 2025/05/15 09:58

Sample crash report:
INFO: task syz-executor:12171 blocked for more than 140 seconds.
      Not tainted 6.16.0-rc4-syzkaller-00049-gb4911fb0b060 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:28264 pid:12171 tgid:12171 ppid:1      task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5396 [inline]
 __schedule+0x16f5/0x4d00 kernel/sched/core.c:6785
 __schedule_loop kernel/sched/core.c:6863 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6878
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6935
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x724/0xe80 kernel/locking/mutex.c:747
 rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083
 ops_init+0x359/0x5c0 net/core/net_namespace.c:138
 setup_net+0x219/0x4b0 net/core/net_namespace.c:442
 copy_net_ns+0x31b/0x4d0 net/core/net_namespace.c:574
 create_new_namespaces+0x3f3/0x720 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x11c/0x170 kernel/nsproxy.c:218
 ksys_unshare+0x4c8/0x8c0 kernel/fork.c:3121
 __do_sys_unshare kernel/fork.c:3192 [inline]
 __se_sys_unshare kernel/fork.c:3190 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3190
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcbc9590127
RSP: 002b:00007fcbc98dffa8 EFLAGS: 00000206 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007fcbc9612461 RCX: 00007fcbc9590127
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 0000000000000000 R08: 00007fcbca2e7d60 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000008
R13: 0000000000000003 R14: 0000000000000009 R15: 0000000000000000
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e13ee20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6770
3 locks held by kworker/u8:3/48:
 #0: ffff88801a489148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801a489148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3321
 #1: ffffc90000b87bc0 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90000b87bc0 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3321
 #2: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:303
2 locks held by kworker/0:2/889:
2 locks held by getty/5596:
 #0: ffff8880344520a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
7 locks held by kworker/0:5/5912:
2 locks held by kworker/0:6/5926:
2 locks held by syz.2.10663/30276:
 #0: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:633 [inline]
 #0: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3396
 #1: ffffffff8e144938 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:336 [inline]
 #1: ffffffff8e144938 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730 kernel/rcu/tree_exp.h:998
1 lock held by syz.7.12174/1740:
 #0: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:633 [inline]
 #0: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3396
2 locks held by kworker/0:3/4110:
2 locks held by kworker/0:7/5655:
1 lock held by syz.0.13651/6414:
 #0: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:633 [inline]
 #0: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3396
1 lock held by syz-executor/8688:
 #0: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:633 [inline]
 #0: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3396
1 lock held by syz.9.15129/12141:
 #0: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:633 [inline]
 #0: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3396
2 locks held by syz-executor/12146:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: ops_exit_rtnl_list net/core/net_namespace.c:174 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: ops_undo_list+0x2a4/0x990 net/core/net_namespace.c:249
2 locks held by syz-executor/12171:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083
6 locks held by kworker/u9:2/12181:
 #0: ffff88803140b948 ((wq_completion)hci6#4){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88803140b948 ((wq_completion)hci6#4){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3321
 #1: ffffc9000b8d7bc0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc9000b8d7bc0 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3321
 #2: ffff888073c08dc0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_cmd_sync_work+0x1d4/0x3a0 net/bluetooth/hci_sync.c:331
 #3: ffff888073c080b8 (&hdev->lock){+.+.}-{4:4}, at: hci_abort_conn_sync+0x1eb/0xdf0 net/bluetooth/hci_sync.c:5626
 #4: ffffffff8f677968 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2053 [inline]
 #4: ffffffff8f677968 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_failed+0x165/0x310 net/bluetooth/hci_conn.c:1275
 #5: ffff888073f55b38 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x70/0x680 net/bluetooth/l2cap_core.c:1762
2 locks held by syz-executor/12186:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083
2 locks held by syz-executor/12190:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083
2 locks held by syz-executor/12192:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083
2 locks held by syz-executor/12202:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083
2 locks held by syz-executor/12214:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083
4 locks held by kworker/u9:4/12232:
 #0: ffff88807d3e8948 ((wq_completion)hci4#4){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88807d3e8948 ((wq_completion)hci4#4){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3321
 #1: ffffc9000431fbc0 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc9000431fbc0 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3321
 #2: ffff8880769800b8 (&hdev->lock){+.+.}-{4:4}, at: hci_remote_features_evt+0x9b/0x8e0 net/bluetooth/hci_event.c:3713
 #3: ffffffff8f677968 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2053 [inline]
 #3: ffffffff8f677968 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_remote_features_evt+0x516/0x8e0 net/bluetooth/hci_event.c:3747
4 locks held by kworker/u9:5/12235:
 #0: ffff88807dac5948 ((wq_completion)hci9#4){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88807dac5948 ((wq_completion)hci9#4){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3321
 #1: ffffc90004fc7bc0 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90004fc7bc0 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3321
 #2: ffff8880769840b8 (&hdev->lock){+.+.}-{4:4}, at: hci_remote_features_evt+0x9b/0x8e0 net/bluetooth/hci_event.c:3713
 #3: ffffffff8f677968 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2053 [inline]
 #3: ffffffff8f677968 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_remote_features_evt+0x516/0x8e0 net/bluetooth/hci_event.c:3747
2 locks held by syz-executor/12236:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083
2 locks held by syz-executor/12237:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083
2 locks held by syz-executor/12238:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083
2 locks held by syz-executor/12244:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083
2 locks held by syz-executor/12245:
 #0: ffffffff8f502d10 (pernet_ops_rwsem){++++}-{4:4}, at: copy_net_ns+0x304/0x4d0 net/core/net_namespace.c:570
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #1: ffffffff8f50f908 (rtnl_mutex){+.+.}-{4:4}, at: register_netdevice_notifier_net+0x1a/0xa0 net/core/dev.c:2083

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.16.0-rc4-syzkaller-00049-gb4911fb0b060 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:307 [inline]
 watchdog+0xfee/0x1030 kernel/hung_task.c:470
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5912 Comm: kworker/0:5 Not tainted 6.16.0-rc4-syzkaller-00049-gb4911fb0b060 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: wg-crypt-wg2 wg_packet_tx_worker
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x0/0x90 kernel/kcov.c:313
Code: 7c 11 10 48 89 74 11 18 48 89 44 11 20 e9 d8 7f a9 09 cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 8b 04 24 65 48 8b 14 25 08 00 9d 92 65 8b 0d 38 ad
RSP: 0018:ffffc90004e9f038 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: dffffc0000000000
RDX: ffff888055cd62c8 RSI: 0000000000000001 RDI: 0000000000000004
RBP: ffffc90004e9f1d0 R08: ffffffff8fa106f7 R09: 1ffffffff1f420de
R10: dffffc0000000000 R11: ffffffff81679410 R12: 1ffff110034acc81
R13: ffff88801a566408 R14: ffff888055cd6348 R15: 1ffff1100ab9ac69
FS:  0000000000000000(0000) GS:ffff888125c50000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb75b67eaa8 CR3: 000000000df38000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 fq_flow_add_tail net/sched/sch_fq.c:200 [inline]
 fq_dequeue+0x9d9/0x2650 net/sched/sch_fq.c:698
 dequeue_skb net/sched/sch_generic.c:294 [inline]
 qdisc_restart net/sched/sch_generic.c:399 [inline]
 __qdisc_run+0x23c/0x15f0 net/sched/sch_generic.c:417
 __dev_xmit_skb net/core/dev.c:4171 [inline]
 __dev_queue_xmit+0xfe1/0x3a70 net/core/dev.c:4679
 dev_queue_xmit include/linux/netdevice.h:3355 [inline]
 neigh_hh_output include/net/neighbour.h:523 [inline]
 neigh_output include/net/neighbour.h:537 [inline]
 ip6_finish_output2+0x11bc/0x16a0 net/ipv6/ip6_output.c:141
 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline]
 ip6_finish_output+0x234/0x7d0 net/ipv6/ip6_output.c:226
 ip6tunnel_xmit include/net/ip6_tunnel.h:161 [inline]
 udp_tunnel6_xmit_skb+0x5da/0xa60 net/ipv6/ip6_udp_tunnel.c:111
 send6+0x5aa/0x8d0 drivers/net/wireguard/socket.c:152
 wg_socket_send_skb_to_peer+0x111/0x1d0 drivers/net/wireguard/socket.c:178
 wg_packet_create_data_done drivers/net/wireguard/send.c:251 [inline]
 wg_packet_tx_worker+0x1c8/0x7c0 drivers/net/wireguard/send.c:276
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
IPVS: dh: UDP 224.0.0.2:0 - no destination available
IPVS: dh: UDP 224.0.0.2:0 - no destination available
IPVS: dh: UDP 224.0.0.2:0 - no destination available

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/03 08:49 upstream b4911fb0b060 115ceea7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce INFO: task hung in register_netdevice_notifier_net
2025/06/07 00:07 net 82cbd06f327f f61267d4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce INFO: task hung in register_netdevice_notifier_net
* Struck through repros no longer work on HEAD.