INFO: task kworker/u8:9:1335 blocked for more than 146 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u8:9 state:D stack:27000 pid:1335 tgid:1335 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: events_unbound linkwatch_event Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0xfee/0x6120 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7008 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7065 __mutex_lock_common kernel/locking/mutex.c:692 [inline] __mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776 linkwatch_event+0x51/0xc0 net/core/link_watch.c:313 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276 process_scheduled_works kernel/workqueue.c:3359 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 INFO: task kworker/u8:13:2985 blocked for more than 146 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u8:13 state:D stack:24616 pid:2985 tgid:2985 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: netns cleanup_net Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0xfee/0x6120 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7008 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7065 __mutex_lock_common kernel/locking/mutex.c:692 [inline] __mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776 rtnl_net_lock include/linux/rtnetlink.h:130 [inline] rtnl_net_dev_lock+0x146/0x360 net/core/dev.c:2162 unregister_netdevice_notifier_dev_net+0x2c/0x2d0 net/core/dev.c:2207 nsim_destroy+0xf6/0x830 drivers/net/netdevsim/netdev.c:1175 __nsim_dev_port_del+0x189/0x240 drivers/net/netdevsim/dev.c:1528 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1540 [inline] nsim_dev_reload_destroy+0x10a/0x4a0 drivers/net/netdevsim/dev.c:1764 nsim_dev_reload_down+0x66/0xd0 drivers/net/netdevsim/dev.c:1038 devlink_reload+0x173/0x790 net/devlink/dev.c:461 devlink_pernet_pre_exit+0x222/0x330 net/devlink/core.c:507 ops_pre_exit_list net/core/net_namespace.c:161 [inline] ops_undo_list+0x187/0xab0 net/core/net_namespace.c:234 cleanup_net+0x499/0x920 net/core/net_namespace.c:704 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276 process_scheduled_works kernel/workqueue.c:3359 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Showing all locks held in the system: 2 locks held by kthreadd/2: 2 locks held by kworker/0:0/9: 3 locks held by kworker/0:1/10: #0: ffff88813fe63148 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1310/0x19a0 kernel/workqueue.c:3251 #1: ffffc900000f7d08 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x988/0x19a0 kernel/workqueue.c:3252 #2: ffffffff90616168 (rtnl_mutex){+.+.}-{4:4}, at: switchdev_deferred_process_work+0xe/0x20 net/switchdev/switchdev.c:104 3 locks held by kworker/u8:0/12: 3 locks held by kworker/u8:1/13: 2 locks held by kworker/1:0/24: 1 lock held by khungtaskd/30: #0: ffffffff8e7e7760 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline] #0: ffffffff8e7e7760 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline] #0: ffffffff8e7e7760 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775 3 locks held by kworker/u8:2/35: 3 locks held by kworker/u8:3/49: 5 locks held by kworker/u9:0/51: #0: ffff888043150948 ((wq_completion)hci5){+.+.}-{0:0}, at: process_one_work+0x1310/0x19a0 kernel/workqueue.c:3251 #1: ffffc90000bb7d08 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x988/0x19a0 kernel/workqueue.c:3252 #2: ffff88807dbd4ec0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_cmd_sync_work+0x18a/0x470 net/bluetooth/hci_sync.c:331 #3: ffff88807dbd40c0 (&hdev->lock){+.+.}-{4:4}, at: hci_abort_conn_sync+0x141/0xb20 net/bluetooth/hci_sync.c:5734 #4: ffffffff908af088 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2136 [inline] #4: ffffffff908af088 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_failed+0x119/0x360 net/bluetooth/hci_conn.c:1342 3 locks held by kworker/u8:4/58: 3 locks held by kworker/u8:5/83: 3 locks held by kworker/u8:6/151: 4 locks held by kworker/u8:7/1091: 3 locks held by kworker/u8:8/1108: 3 locks held by kworker/u8:9/1335: #0: ffff88813fea4148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1310/0x19a0 kernel/workqueue.c:3251 #1: ffffc9000525fd08 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x988/0x19a0 kernel/workqueue.c:3252 #2: ffffffff90616168 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0x51/0xc0 net/core/link_watch.c:313 4 locks held by kworker/u8:10/1340: 3 locks held by kworker/u8:11/1351: 3 locks held by kworker/u8:12/2975: 6 locks held by kworker/u8:13/2985: #0: ffff88801c6b6948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x1310/0x19a0 kernel/workqueue.c:3251 #1: ffffc9000eb0fd08 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x988/0x19a0 kernel/workqueue.c:3252 #2: ffffffff905fd910 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xb8/0x920 net/core/net_namespace.c:675 #3: ffff88807bbd6130 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:949 [inline] #3: ffff88807bbd6130 (&dev->mutex){....}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:108 [inline] #3: ffff88807bbd6130 (&dev->mutex){....}-{4:4}, at: devlink_pernet_pre_exit+0x185/0x330 net/devlink/core.c:504 #4: ffff88807bbd5250 (&devlink->lock_key#4){+.+.}-{4:4}, at: devl_lock net/devlink/core.c:274 [inline] #4: ffff88807bbd5250 (&devlink->lock_key#4){+.+.}-{4:4}, at: devl_dev_lock net/devlink/devl_internal.h:109 [inline] #4: ffff88807bbd5250 (&devlink->lock_key#4){+.+.}-{4:4}, at: devlink_pernet_pre_exit+0x18f/0x330 net/devlink/core.c:504 #5: ffffffff90616168 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #5: ffffffff90616168 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_dev_lock+0x146/0x360 net/core/dev.c:2162 3 locks held by kworker/u8:14/3047: 3 locks held by kworker/R-ipv6_/3189: #0: ffff88803334f148 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x1310/0x19a0 kernel/workqueue.c:3251 #1: ffffc9000f0bfc70 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x988/0x19a0 kernel/workqueue.c:3252 #2: ffffffff90616168 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline] #2: ffffffff90616168 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x12/0x30 net/ipv6/addrconf.c:4738 1 lock held by kworker/R-bat_e/3414: #0: ffffffff8e694e48 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2749 [inline] #0: ffffffff8e694e48 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xb7b/0x14a0 kernel/workqueue.c:3611 2 locks held by klogd/5188: 2 locks held by udevd/5199: 2 locks held by crond/5572: 2 locks held by getty/5587: #0: ffff8880389900a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211 2 locks held by syz-executor/5816: 3 locks held by kworker/1:3/5817: 7 locks held by kworker/u9:2/5831: 5 locks held by kworker/u9:3/5833: #0: ffff888038646148 ((wq_completion)hci7){+.+.}-{0:0}, at: process_one_work+0x1310/0x19a0 kernel/workqueue.c:3251 #1: ffffc90003c17d08 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work+0x988/0x19a0 kernel/workqueue.c:3252 #2: ffff88807a268ec0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_cmd_sync_work+0x18a/0x470 net/bluetooth/hci_sync.c:331 #3: ffff88807a2680c0 (&hdev->lock){+.+.}-{4:4}, at: hci_abort_conn_sync+0x141/0xb20 net/bluetooth/hci_sync.c:5734 #4: ffffffff908af088 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_connect_cfm include/net/bluetooth/hci_core.h:2136 [inline] #4: ffffffff908af088 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_failed+0x119/0x360 net/bluetooth/hci_conn.c:1342 3 locks held by kworker/0:3/5881: 5 locks held by kworker/1:4/5888: 6 locks held by kworker/1:5/5912: 4 locks held by kworker/0:6/5921: 1 lock held by syz-executor/7818: 2 locks held by syz-executor/7823: 1 lock held by kworker/R-wg-cr/7839: #0: ffffffff8e694e48 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2749 [inline] #0: ffffffff8e694e48 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xb7b/0x14a0 kernel/workqueue.c:3611 1 lock held by kworker/R-wg-cr/7840: #0: ffffffff8e694e48 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_attach_to_pool+0x27/0x420 kernel/workqueue.c:2691 1 lock held by kworker/R-wg-cr/7842: #0: ffffffff8e694e48 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_attach_to_pool+0x27/0x420 kernel/workqueue.c:2691 1 lock held by kworker/R-wg-cr/7843: #0: ffffffff8e694e48 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_attach_to_pool+0x27/0x420 kernel/workqueue.c:2691 1 lock held by kworker/R-wg-cr/7845: 1 lock held by kworker/R-wg-cr/7847: #0: ffffffff8e694e48 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_attach_to_pool+0x27/0x420 kernel/workqueue.c:2691 1 lock held by kworker/R-wg-cr/7848: #0: ffffffff8e694e48 (wq_pool_attach_mutex){+.+.}-{4:4}, at: worker_detach_from_pool kernel/workqueue.c:2749 [inline] #0: ffffffff8e694e48 (wq_pool_attach_mutex){+.+.}-{4:4}, at: rescuer_thread+0xb7b/0x14a0 kernel/workqueue.c:3611 3 locks held by kworker/1:7/7852: #0: ffff88813fe61d48 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work+0x1310/0x19a0 kernel/workqueue.c:3251 #1: ffffc90003f87d08 ((reg_check_chans).work){+.+.}-{0:0}, at: process_one_work+0x988/0x19a0 kernel/workqueue.c:3252 #2: ffffffff90616168 (rtnl_mutex){+.+.}-{4:4}, at: reg_check_chans_work+0x91/0x11d0 net/wireless/reg.c:2462 4 locks held by kworker/1:8/8076: 2 locks held by syz.7.413/8132: 1 lock held by syz.5.415/8153: 2 locks held by syz.5.415/8160: 2 locks held by syz.4.416/8164: 1 lock held by syz.6.417/8168: 2 locks held by dhcpcd/8174: ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x1d7/0x230 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline] __sys_info lib/sys_info.c:157 [inline] sys_info+0x141/0x190 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline] watchdog+0xd25/0x1050 kernel/hung_task.c:515 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 5912 Comm: kworker/1:5 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Workqueue: events mptcp_worker RIP: 0010:check_wait_context kernel/locking/lockdep.c:4882 [inline] RIP: 0010:__lock_acquire+0x312/0x2630 kernel/locking/lockdep.c:5187 Code: 89 e8 4d 89 e5 49 89 dc 4c 89 f3 45 89 ce 49 89 c1 eb 42 48 8d 04 80 48 8d 04 80 48 8d 34 c5 a0 ab 14 96 0f b6 86 c4 00 00 00 <84> c0 74 12 41 38 c7 44 0f 47 f8 80 be c6 00 00 00 02 44 0f 44 f8 RSP: 0018:ffffc90000a079d0 EFLAGS: 00000003 RAX: 0000000000000003 RBX: ffff88801f30e778 RCX: 0000000000000006 RDX: 0000000000000001 RSI: ffffffff9614b118 RDI: 0000000000000020 RBP: ffff88801f30db80 R08: 0000000000000000 R09: 0000000000000007 R10: 0000000000000006 R11: 0000000000000000 R12: ffff88801f30e7c8 R13: 0000000000000000 R14: 0000000000000004 R15: 0000000000000003 FS: 0000000000000000(0000) GS:ffff888124443000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3f67879ff8 CR3: 0000000038518000 CR4: 00000000003526f0 Call Trace: lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1cf/0x380 kernel/locking/lockdep.c:5825 rcu_lock_acquire include/linux/rcupdate.h:312 [inline] rcu_read_lock include/linux/rcupdate.h:850 [inline] class_rcu_constructor include/linux/rcupdate.h:1193 [inline] unwind_next_frame+0xd1/0x1ea0 arch/x86/kernel/unwind_orc.c:495 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2685 [inline] slab_free mm/slub.c:6165 [inline] kmem_cache_free+0x124/0x6a0 mm/slub.c:6295 kfree_skbmem+0x19a/0x210 net/core/skbuff.c:1151 __kfree_skb net/core/skbuff.c:1218 [inline] sk_skb_reason_drop+0x10f/0x1b0 net/core/skbuff.c:1255 kfree_skb_reason include/linux/skbuff.h:1322 [inline] kfree_skb include/linux/skbuff.h:1331 [inline] ip6_mc_input+0x832/0xf50 net/ipv6/ip6_input.c:593 dst_input include/net/dst.h:480 [inline] ip6_rcv_finish+0x294/0x300 net/ipv6/ip6_input.c:79 ip_sabotage_in+0x21e/0x290 net/bridge/br_netfilter_hooks.c:990 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0xbf/0x220 net/netfilter/core.c:623 nf_hook.constprop.0+0x2a6/0x750 include/linux/netfilter.h:273 NF_HOOK include/linux/netfilter.h:316 [inline] ipv6_rcv+0xa4/0x3d0 net/ipv6/ip6_input.c:311 __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:6176 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6289 netif_receive_skb_internal net/core/dev.c:6375 [inline] netif_receive_skb+0x139/0x820 net/core/dev.c:6434 NF_HOOK include/linux/netfilter.h:318 [inline] NF_HOOK include/linux/netfilter.h:312 [inline] br_pass_frame_up+0x346/0x490 net/bridge/br_input.c:70 br_handle_frame_finish+0xa74/0x1f60 net/bridge/br_input.c:235 br_nf_hook_thresh+0x30d/0x420 net/bridge/br_netfilter_hooks.c:1167 br_nf_pre_routing_finish_ipv6+0x769/0xfb0 net/bridge/br_netfilter_ipv6.c:154 NF_HOOK include/linux/netfilter.h:318 [inline] br_nf_pre_routing_ipv6+0x39c/0x8b0 net/bridge/br_netfilter_ipv6.c:184 br_nf_pre_routing+0x90d/0x1550 net/bridge/br_netfilter_hooks.c:508 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_bridge_pre net/bridge/br_input.c:291 [inline] br_handle_frame+0xcdd/0x1520 net/bridge/br_input.c:442 __netif_receive_skb_core.constprop.0+0x6c5/0x3550 net/core/dev.c:6063 __netif_receive_skb_one_core+0xb0/0x1e0 net/core/dev.c:6174 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6289 process_backlog+0x37a/0x1580 net/core/dev.c:6640 __napi_poll.constprop.0+0xaf/0x450 net/core/dev.c:7704 napi_poll net/core/dev.c:7767 [inline] net_rx_action+0xa40/0xf20 net/core/dev.c:7924 handle_softirqs+0x1eb/0x9e0 kernel/softirq.c:622 do_softirq kernel/softirq.c:523 [inline] do_softirq+0xac/0xe0 kernel/softirq.c:510 __local_bh_enable_ip+0xf8/0x120 kernel/softirq.c:450 spin_unlock_bh include/linux/spinlock.h:395 [inline] mptcp_check_and_set_pending net/mptcp/protocol.c:1569 [inline] mptcp_check_and_set_pending+0x122/0x180 net/mptcp/protocol.c:1564 __mptcp_retrans+0x712/0xd70 net/mptcp/protocol.c:2828 mptcp_release_cb+0x3cb/0x710 net/mptcp/protocol.c:3645 release_sock+0x1d0/0x220 net/core/sock.c:3798 mptcp_worker+0x634/0x1420 net/mptcp/protocol.c:2980 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276 process_scheduled_works kernel/workqueue.c:3359 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245