INFO: task hung in ip_tunnel_delete_nets

Status: upstream: reported on 2026/06/07 20:57
Reported-by: syzbot+ac95389c06ff9d8eb474@syzkaller.appspotmail.com
First crash: 66d, last: 4d15h
Similar bugs (12)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: task hung in ip_tunnel_delete_nets 1 1 1196d 1196d 0/3 auto-obsoleted due to no activity on 2023/08/23 09:02
linux-6.1 INFO: task hung in ip_tunnel_delete_nets (2) 1 9 749d 812d 0/3 auto-obsoleted due to no activity on 2024/11/01 23:50
upstream INFO: task hung in ip_tunnel_delete_nets (3) net 1 1 2164d 2164d 0/29 auto-closed as invalid on 2020/12/07 06:22
linux-4.19 INFO: task hung in ip_tunnel_delete_nets 1 1 1717d 1717d 0/1 auto-closed as invalid on 2022/03/29 13:03
upstream INFO: task hung in ip_tunnel_delete_nets (2) net 1 2 2277d 2289d 0/29 auto-closed as invalid on 2020/08/16 16:51
upstream INFO: task hung in ip_tunnel_delete_nets net 1 2 2493d 2497d 0/29 closed as invalid on 2019/10/23 07:54
upstream INFO: task hung in ip_tunnel_delete_nets (6) net 1 2 905d 945d 0/29 auto-obsoleted due to no activity on 2024/05/19 21:58
upstream INFO: task hung in ip_tunnel_delete_nets (4) net 1 2 1506d 1506d 0/29 auto-closed as invalid on 2022/09/26 14:02
linux-4.19 INFO: task hung in ip_tunnel_delete_nets (2) 1 1 1332d 1332d 0/1 auto-obsoleted due to no activity on 2023/04/18 11:45
linux-6.1 INFO: task hung in ip_tunnel_delete_nets (3) 1 1 231d 231d 0/3 auto-obsoleted due to no activity on 2026/04/04 00:00
linux-6.1 INFO: task hung in ip_tunnel_delete_nets (4) 1 1 77d 77d 0/3 upstream: reported on 2026/05/27 21:28
upstream INFO: task hung in ip_tunnel_delete_nets (5) net 1 15 1070d 1376d 0/29 auto-obsoleted due to no activity on 2023/12/06 23:00

Sample crash report:
INFO: task kworker/u4:3:49 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:3    state:D stack:24792 pid:49    ppid:2      flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 ip_tunnel_delete_nets+0xd6/0x380 net/ipv4/ip_tunnel.c:1152
 ops_exit_list net/core/net_namespace.c:178 [inline]
 cleanup_net+0x792/0xbb0 net/core/net_namespace.c:652
 process_one_work kernel/workqueue.c:2657 [inline]
 process_scheduled_works+0xa60/0x1600 kernel/workqueue.c:2734
 worker_thread+0xa5e/0xfe0 kernel/workqueue.c:2815
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
INFO: task dhcpcd:5435 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:dhcpcd          state:D stack:20968 pid:5435  ppid:5434   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 rtnl_lock net/core/rtnetlink.c:78 [inline]
 rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
 netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x61b/0x980 net/socket.c:2595
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2649
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2687 [inline]
 __se_sys_sendmsg+0x1d0/0x2c0 net/socket.c:2685
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f419bbd2407
RSP: 002b:00007ffeab88df00 EFLAGS: 00000202 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f419bb48740 RCX: 00007f419bbd2407
RDX: 0000000000000000 RSI: 00007ffeab8a20e0 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffeab8b2310
R13: 00007f419bb486c8 R14: 0000000000000030 R15: 00007ffeab8a20e0
 </TASK>
INFO: task syz-executor:11339 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:22344 pid:11339 ppid:1      flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_timeout+0xc1/0x2d0 kernel/time/timer.c:2144
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x2c6/0x5a0 kernel/sched/completion.c:148
 __flush_work+0x92f/0xac0 kernel/workqueue.c:3475
 xfrm_flush_gc net/xfrm/xfrm_state.c:2842 [inline]
 xfrm_dev_state_flush+0x286/0x710 net/xfrm/xfrm_state.c:946
 xfrm_dev_unregister net/xfrm/xfrm_device.c:520 [inline]
 xfrm_dev_event+0x1b7/0x3d0 net/xfrm/xfrm_device.c:541
 notifier_call_chain+0x18f/0x380 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2077 [inline]
 call_netdevice_notifiers net/core/dev.c:2091 [inline]
 unregister_netdevice_many_notify+0x1037/0x1910 net/core/dev.c:11124
 unregister_netdevice_many net/core/dev.c:11180 [inline]
 unregister_netdevice_queue+0x2e9/0x330 net/core/dev.c:11060
 unregister_netdevice include/linux/netdevice.h:3139 [inline]
 nsim_destroy+0x4d/0x180 drivers/net/netdevsim/netdev.c:418
 __nsim_dev_port_del+0x14d/0x1b0 drivers/net/netdevsim/dev.c:1428
 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1440 [inline]
 nsim_dev_reload_destroy+0x283/0x480 drivers/net/netdevsim/dev.c:1662
 nsim_drv_remove+0x58/0x170 drivers/net/netdevsim/dev.c:1677
 device_remove drivers/base/dd.c:626 [inline]
 __device_release_driver drivers/base/dd.c:1351 [inline]
 device_release_driver_internal+0x408/0x6f0 drivers/base/dd.c:1374
 bus_remove_device+0x43b/0x520 drivers/base/bus.c:624
 device_del+0x51f/0x910 drivers/base/core.c:3889
 device_unregister+0x20/0xc0 drivers/base/core.c:3930
 nsim_bus_dev_del drivers/net/netdevsim/bus.c:310 [inline]
 del_device_store+0x2b6/0x370 drivers/net/netdevsim/bus.c:219
 kernfs_fop_write_iter+0x3a4/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x474/0x9a0 fs/read_write.c:584
 ksys_write+0x151/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4e44b5e90e
RSP: 002b:00007ffdebe32c58 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000055557d9d0500 RCX: 00007f4e44b5e90e
RDX: 0000000000000001 RSI: 00007ffdebe32ce0 RDI: 0000000000000005
RBP: 00007f4e44c358a7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffdebe32ce0 R14: 00007f4e45954620 R15: 0000000000000003
 </TASK>

Showing all locks held in the system:
1 lock held by kworker/R-rcu_g/4:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
2 locks held by kworker/0:0/8:
2 locks held by kworker/0:1/9:
1 lock held by kworker/R-mm_pe/13:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
1 lock held by khungtaskd/28:
 #0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
3 locks held by kworker/u4:2/41:
 #0: ffff888017c71938 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff888017c71938 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc90000b1fd00 ((work_completion)(&pool->idle_cull_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc90000b1fd00 ((work_completion)(&pool->idle_cull_work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: idle_cull_fn+0xd7/0x550 kernel/workqueue.c:2385
4 locks held by kworker/u4:3/49:
 #0: ffff88801a25d138 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff88801a25d138 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc90000b9fd00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc90000b9fd00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffffffff8e3ca0d0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x14c/0xbb0 net/core/net_namespace.c:606
 #3: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: ip_tunnel_delete_nets+0xd6/0x380 net/ipv4/ip_tunnel.c:1152
2 locks held by kworker/0:1H/1096:
1 lock held by kworker/R-dm_bu/2789:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
1 lock held by dhcpcd/5435:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
2 locks held by getty/5530:
 #0: ffff888031e8a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000325e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x428/0x1370 drivers/tty/n_tty.c:2217
4 locks held by kworker/u5:2/5775:
 #0: ffff8880558fa138 ((wq_completion)hci14#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff8880558fa138 ((wq_completion)hci14#2){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc90004387d00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc90004387d00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffff8880391000b8 (&hdev->lock){+.+.}-{3:3}, at: hci_remote_features_evt+0x97/0x900 net/bluetooth/hci_event.c:3683
 #3: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2001 [inline]
 #3: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_remote_features_evt+0x535/0x900 net/bluetooth/hci_event.c:3717
7 locks held by kworker/u5:3/5782:
 #0: ffff88803018bd38 ((wq_completion)hci4){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff88803018bd38 ((wq_completion)hci4){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc900043d7d00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc900043d7d00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffff88805ebc0e70 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x1cc/0x380 net/bluetooth/hci_sync.c:332
 #3: ffff88805ebc00b8 (&hdev->lock){+.+.}-{3:3}, at: hci_abort_conn_sync+0x864/0xe60 net/bluetooth/hci_sync.c:5715
 #4: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2001 [inline]
 #4: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_failed+0x145/0x2e0 net/bluetooth/hci_conn.c:1258
 #5: ffff8880311b9b38 (&conn->lock#2){+.+.}-{3:3}, at: l2cap_conn_del+0x7b/0x630 net/bluetooth/l2cap_core.c:1793
 #6: ffffffff8d137778 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline]
 #6: ffffffff8d137778 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3da/0x880 kernel/rcu/tree_exp.h:1004
4 locks held by kworker/u5:5/5786:
 #0: ffff888059afd538 ((wq_completion)hci12#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff888059afd538 ((wq_completion)hci12#2){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc9000442fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc9000442fd00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffff888044a200b8 (&hdev->lock){+.+.}-{3:3}, at: hci_remote_features_evt+0x97/0x900 net/bluetooth/hci_event.c:3683
 #3: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2001 [inline]
 #3: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_remote_features_evt+0x535/0x900 net/bluetooth/hci_event.c:3717
5 locks held by kworker/u5:6/5789:
 #0: ffff88801aaf6138 ((wq_completion)hci5){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff88801aaf6138 ((wq_completion)hci5){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc9000445fd00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc9000445fd00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffff88807ceace70 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x1cc/0x380 net/bluetooth/hci_sync.c:332
 #3: ffff88807ceac0b8 (&hdev->lock){+.+.}-{3:3}, at: hci_abort_conn_sync+0x864/0xe60 net/bluetooth/hci_sync.c:5715
 #4: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2001 [inline]
 #4: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_failed+0x145/0x2e0 net/bluetooth/hci_conn.c:1258
1 lock held by kworker/R-wg-cr/5807:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
1 lock held by kworker/R-wg-cr/5809:
1 lock held by kworker/R-wg-cr/5810:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
1 lock held by kworker/R-wg-cr/5811:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
1 lock held by kworker/R-wg-cr/5812:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
1 lock held by kworker/R-wg-cr/5813:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
2 locks held by kworker/0:3/5818:
3 locks held by kworker/0:5/5843:
 #0: ffff888017c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff888017c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc900046ffd00 (xfrm_state_gc_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc900046ffd00 (xfrm_state_gc_work){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffffffff8d137778 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:292 [inline]
 #2: ffffffff8d137778 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x306/0x880 kernel/rcu/tree_exp.h:1004
3 locks held by kworker/0:7/7432:
1 lock held by syz-executor/7545:
1 lock held by syz-executor/7547:
1 lock held by kworker/R-wg-cr/7553:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_detach_from_pool+0x46/0x260 kernel/workqueue.c:2160
1 lock held by kworker/R-wg-cr/7556:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
1 lock held by kworker/R-wg-cr/7558:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_detach_from_pool+0x46/0x260 kernel/workqueue.c:2160
1 lock held by kworker/R-wg-cr/7581:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
2 locks held by kworker/0:8/7616:
2 locks held by kworker/R-wg-cr/7808:
3 locks held by kworker/u4:11/7812:
 #0: ffff88802c952d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff88802c952d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc90003487d00 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc90003487d00 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0x19/0x30 net/ipv6/addrconf.c:4730
1 lock held by kworker/R-wg-cr/7813:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
1 lock held by kworker/R-wg-cr/7824:
 #0: ffffffff8cfdda08 (wq_pool_attach_mutex){+.+.}-{3:3}, at: worker_attach_to_pool+0x31/0x370 kernel/workqueue.c:2126
7 locks held by syz-executor/11339:
 #0: ffff88802d5cc418 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x21e/0x9a0 fs/read_write.c:580
 #1: ffff88806d37ac88 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1dc/0x520 fs/kernfs/file.c:343
 #2: ffff888024a344e0 (kn->active#53){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #2: ffff888024a344e0 (kn->active#53){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x236/0x520 fs/kernfs/file.c:344
 #3: ffffffff8dcb7788 (nsim_bus_dev_list_lock){+.+.}-{3:3}, at: del_device_store+0xd7/0x370 drivers/net/netdevsim/bus.c:209
 #4: ffff888064dc5130 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:1094 [inline]
 #4: ffff888064dc5130 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1174 [inline]
 #4: ffff888064dc5130 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xa7/0x6f0 drivers/base/dd.c:1371
 #5: ffff888064dc6250 (&devlink->lock_key#6){+.+.}-{3:3}, at: nsim_drv_remove+0x50/0x170 drivers/net/netdevsim/dev.c:1676
 #6: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: nsim_destroy+0x3f/0x180 drivers/net/netdevsim/netdev.c:417
1 lock held by syz.1.1062/11524:
1 lock held by syz.1.1062/11530:
1 lock held by syz.0.1064/11528:
1 lock held by syz-executor/11540:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/11544:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/11546:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/11549:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/11557:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/11560:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/11563:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/11566:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/11574:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/11578:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/11580:
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d70c8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
5 locks held by kworker/u5:0/11582:
 #0: ffff88801bb5ad38 ((wq_completion)hci2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff88801bb5ad38 ((wq_completion)hci2){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc900037e7d00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc900037e7d00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffff88801cf08e70 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x1cc/0x380 net/bluetooth/hci_sync.c:332
 #3: ffff88801cf080b8 (&hdev->lock){+.+.}-{3:3}, at: hci_abort_conn_sync+0x864/0xe60 net/bluetooth/hci_sync.c:5715
 #4: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2001 [inline]
 #4: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_failed+0x145/0x2e0 net/bluetooth/hci_conn.c:1258
5 locks held by kworker/u5:4/11583:
 #0: ffff88802cb73538 ((wq_completion)hci6){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff88802cb73538 ((wq_completion)hci6){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc900037f7d00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc900037f7d00 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffff88801e3bce70 (&hdev->req_lock){+.+.}-{3:3}, at: hci_cmd_sync_work+0x1cc/0x380 net/bluetooth/hci_sync.c:332
 #3: ffff88801e3bc0b8 (&hdev->lock){+.+.}-{3:3}, at: hci_abort_conn_sync+0x864/0xe60 net/bluetooth/hci_sync.c:5715
 #4: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2001 [inline]
 #4: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_failed+0x145/0x2e0 net/bluetooth/hci_conn.c:1258
4 locks held by kworker/u5:9/11585:
 #0: ffff88805f36e138 ((wq_completion)hci13#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff88805f36e138 ((wq_completion)hci13#2){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc90003817d00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc90003817d00 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffff8880391040b8 (&hdev->lock){+.+.}-{3:3}, at: hci_remote_features_evt+0x97/0x900 net/bluetooth/hci_event.c:3683
 #3: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2001 [inline]
 #3: ffffffff8e543f48 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_remote_features_evt+0x535/0x900 net/bluetooth/hci_event.c:3717

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a6/0x3e0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf59/0xfa0 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 11524 Comm: syz.1.1062 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__preempt_count_add arch/x86/include/asm/preempt.h:80 [inline]
RIP: 0010:preempt_count_add+0x3b/0x1a0 kernel/sched/core.c:5845
Code: ff df 48 c7 c0 80 24 2f 97 48 c1 e8 03 42 0f b6 04 38 84 c0 0f 85 eb 00 00 00 83 3d 0e 3c d2 15 00 75 07 65 8b 05 cd cf a6 7e <65> 01 3d c6 cf a6 7e 48 c7 c0 80 24 2f 97 48 c1 e8 03 42 0f b6 04
RSP: 0018:ffffc90000007338 EFLAGS: 00000246
RAX: 0000000080000101 RBX: 1ffff92000000e85 RCX: ffffffff972f2403
RDX: ffff888027d20000 RSI: 0000000000000002 RDI: 0000000000000001
RBP: 0000000000000002 R08: ffffc900000074f0 R09: 000000000000000f
R10: 0000000000000004 R11: 0000000000000100 R12: ffffc90000007e40
R13: ffffc90000007428 R14: ffffc90000007460 R15: dffffc0000000000
FS:  00007fc3d78986c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000058 CR3: 00000000556c5000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 unwind_next_frame+0xb7/0x2990 arch/x86/kernel/unwind_orc.c:479
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6a/0x4d0 mm/slab.h:770
 slab_alloc_node mm/slub.c:3495 [inline]
 kmem_cache_alloc_node+0x1af/0x310 mm/slub.c:3540
 kmalloc_reserve+0x95/0x240 net/core/skbuff.c:562
 __alloc_skb+0x138/0x2c0 net/core/skbuff.c:653
 skb_copy+0x126/0x700 net/core/skbuff.c:1984
 mac80211_hwsim_tx_frame_no_nl+0xcb2/0x11e0 drivers/net/wireless/virtual/mac80211_hwsim.c:1840
 mac80211_hwsim_tx_frame+0x1b5/0x200 drivers/net/wireless/virtual/mac80211_hwsim.c:2176
 mac80211_hwsim_beacon_tx+0x3df/0x770 drivers/net/wireless/virtual/mac80211_hwsim.c:2269
 __iterate_interfaces+0x225/0x4c0 net/mac80211/util.c:766
 ieee80211_iterate_active_interfaces_atomic+0xdb/0x180 net/mac80211/util.c:802
 mac80211_hwsim_beacon+0xbb/0x1b0 drivers/net/wireless/virtual/mac80211_hwsim.c:2295
 __run_hrtimer kernel/time/hrtimer.c:1754 [inline]
 __hrtimer_run_queues+0x525/0xc10 kernel/time/hrtimer.c:1818
 hrtimer_run_softirq+0x177/0x290 kernel/time/hrtimer.c:1835
 handle_softirqs+0x27d/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:instrument_atomic_read include/linux/instrumented.h:68 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:504 [inline]
RIP: 0010:cpu_online include/linux/cpumask.h:1082 [inline]
RIP: 0010:trace_lock_acquire include/trace/events/lock.h:24 [inline]
RIP: 0010:lock_acquire+0xb2/0x420 kernel/locking/lockdep.c:5725
Code: f3 f3 0f 1f 44 00 00 65 8b 05 a6 32 9b 7e 83 f8 08 0f 83 a0 01 00 00 41 89 c6 c1 e8 06 48 8d 3c c5 e8 7a 8c 8e be 08 00 00 00 <e8> e9 6f 77 00 4c 0f a3 35 19 f5 23 0d 73 0d e8 9a b3 08 00 84 c0
RSP: 0018:ffffc90005527a60 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8e8c7ae8
RBP: ffffc90005527b68 R08: 0000000000000001 R09: 0000000000000000
R10: ffffc90005527c60 R11: fffff52000aa4f8f R12: 1ffff92000aa4f58
R13: ffff88801bfc27a0 R14: 0000000000000000 R15: dffffc0000000000
 __might_fault+0xc6/0x120 mm/memory.c:5968
 _copy_from_user+0x2a/0xe0 lib/usercopy.c:14
 copy_from_user include/linux/uaccess.h:183 [inline]
 restore_altstack+0xaf/0x4e0 kernel/signal.c:4299
 __ia32_sys_rt_sigreturn+0x239/0x850 arch/x86/kernel/signal_64.c:263
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc3d693f459
Code: 11 06 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 0c 25
RSP: 002b:00007fc3d7897a80 EFLAGS: 00000202 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007fc3d6c25fa0 RCX: 00007fc3d693f459
RDX: 00007fc3d7897a80 RSI: 00007fc3d7897bb0 RDI: 0000000000000021
RBP: 00007fc3d6a35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007fc3d6c26038 R14: 00007fc3d6c25fa0 R15: 00007ffd663702d8
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/08 11:52 linux-6.6.y 6436c12a2ced 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in ip_tunnel_delete_nets
2026/06/07 20:57 linux-6.6.y 924b4a879cbb cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: task hung in ip_tunnel_delete_nets
* Struck through repros no longer work on HEAD.