INFO: task kworker/1:9:12710 blocked for more than 143 seconds. Tainted: G L syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/1:9 state:D stack:21104 pid:12710 tgid:12710 ppid:2 task_flags:0x4208060 flags:0x00080000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:5256 [inline] __schedule+0x14bc/0x5000 kernel/sched/core.c:6863 __schedule_loop kernel/sched/core.c:6945 [inline] schedule+0x165/0x360 kernel/sched/core.c:6960 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7017 __mutex_lock_common kernel/locking/mutex.c:692 [inline] __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:776 hub_port_connect drivers/usb/core/hub.c:5464 [inline] hub_port_connect_change drivers/usb/core/hub.c:5706 [inline] port_event drivers/usb/core/hub.c:5870 [inline] hub_event+0x21e5/0x4a20 drivers/usb/core/hub.c:5952 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 Showing all locks held in the system: 1 lock held by khungtaskd/31: #0: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #0: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775 5 locks held by kworker/1:1/40: #0: ffff8881422d4948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline] #0: ffff8881422d4948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340 #1: ffffc90000b07b80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline] #1: ffffc90000b07b80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340 #2: ffff888145f02198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:914 [inline] #2: ffff888145f02198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a20 drivers/usb/core/hub.c:5898 #3: ffff888145f06518 (&port_dev->status_lock){+.+.}-{4:4}, at: usb_lock_port drivers/usb/core/hub.c:3251 [inline] #3: ffff888145f06518 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5463 [inline] #3: ffff888145f06518 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5706 [inline] #3: ffff888145f06518 (&port_dev->status_lock){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5870 [inline] #3: ffff888145f06518 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x21b8/0x4a20 drivers/usb/core/hub.c:5952 #4: ffff888145f12168 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5464 [inline] #4: ffff888145f12168 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5706 [inline] #4: ffff888145f12168 (hcd->address0_mutex){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5870 [inline] #4: ffff888145f12168 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x21e5/0x4a20 drivers/usb/core/hub.c:5952 2 locks held by getty/5587: #0: ffff888033bf70a0 (&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 5 locks held by kworker/1:9/12710: #0: ffff8881422d4948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline] #0: ffff8881422d4948 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340 #1: ffffc9000bf9fb80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline] #1: ffffc9000bf9fb80 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340 #2: ffff8880286b4198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:914 [inline] #2: ffff8880286b4198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a20 drivers/usb/core/hub.c:5898 #3: ffff8880286b7518 (&port_dev->status_lock){+.+.}-{4:4}, at: usb_lock_port drivers/usb/core/hub.c:3251 [inline] #3: ffff8880286b7518 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5463 [inline] #3: ffff8880286b7518 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5706 [inline] #3: ffff8880286b7518 (&port_dev->status_lock){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5870 [inline] #3: ffff8880286b7518 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x21b8/0x4a20 drivers/usb/core/hub.c:5952 #4: ffff888145f12168 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5464 [inline] #4: ffff888145f12168 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5706 [inline] #4: ffff888145f12168 (hcd->address0_mutex){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5870 [inline] #4: ffff888145f12168 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x21e5/0x4a20 drivers/usb/core/hub.c:5952 1 lock held by syz.1.6014/27014: 2 locks held by syz.1.6014/27015: #0: ffff88807ddcc148 (&sb->s_type->i_mutex_key#12){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline] #0: ffff88807ddcc148 (&sb->s_type->i_mutex_key#12){+.+.}-{4:4}, at: __sock_release net/socket.c:652 [inline] #0: ffff88807ddcc148 (&sb->s_type->i_mutex_key#12){+.+.}-{4:4}, at: sock_close+0x9b/0x240 net/socket.c:1446 #1: ffffffff8df477f8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline] #1: ffffffff8df477f8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2f6/0x730 kernel/rcu/tree_exp.h:956 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: 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:160 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline] watchdog+0xf3c/0xf80 kernel/hung_task.c:495 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 Sending NMI from CPU 1 to CPUs 0: GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:400 Code: e8 3e 8b a9 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 6f da 0f fd 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f e9 8a a5 39 06 cc 44 89 f9 80 e1 07 RSP: 0018:ffffc90000006738 EFLAGS: 00000006 RAX: 1ffffffff3374205 RBX: 00000000000003f9 RCX: 0000000000000000 RDX: 00000000000003f9 RSI: 0000000000000000 RDI: 0000000000000020 RBP: ffffc90000006910 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: ffffffff8517c410 R12: dffffc0000000000 R13: dffffc0000000000 R14: ffffffff99ba13e0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888126087000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000030d0effc CR3: 0000000075d9c000 CR4: 00000000003526f0 DR0: 0000000000000004 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: serial_port_in include/linux/serial_core.h:806 [inline] serial8250_console_write+0x584/0x1ba0 drivers/tty/serial/8250/8250_port.c:3306 console_emit_next_record kernel/printk/printk.c:3129 [inline] console_flush_one_record kernel/printk/printk.c:3215 [inline] console_flush_all+0x745/0xb60 kernel/printk/printk.c:3289 __console_flush_and_unlock kernel/printk/printk.c:3319 [inline] console_unlock+0xbb/0x190 kernel/printk/printk.c:3359 vprintk_emit+0x4f8/0x5f0 kernel/printk/printk.c:2426 _printk+0xcf/0x120 kernel/printk/printk.c:2451 gred_dequeue+0x4e6/0x6f0 net/sched/sch_gred.c:273 dequeue_skb net/sched/sch_generic.c:297 [inline] qdisc_restart net/sched/sch_generic.c:402 [inline] __qdisc_run+0x23f/0x1510 net/sched/sch_generic.c:420 qdisc_run+0xc7/0x300 include/net/pkt_sched.h:120 __dev_xmit_skb net/core/dev.c:4250 [inline] __dev_queue_xmit+0x186d/0x3140 net/core/dev.c:4783 dev_queue_xmit include/linux/netdevice.h:3381 [inline] neigh_hh_output include/net/neighbour.h:540 [inline] neigh_output include/net/neighbour.h:554 [inline] ip6_finish_output2+0xf70/0x1480 net/ipv6/ip6_output.c:136 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247 ip6_send_skb+0x1d5/0x390 net/ipv6/ip6_output.c:1994 icmp6_send+0x12fe/0x1990 net/ipv6/icmp.c:827 __icmpv6_send include/linux/icmpv6.h:28 [inline] icmpv6_send include/linux/icmpv6.h:49 [inline] ip6_pkt_drop+0x53d/0x620 net/ipv6/route.c:4620 ip6_pkt_discard_out+0xf2/0x120 net/ipv6/route.c:4633 ip6tunnel_xmit include/net/ip6_tunnel.h:162 [inline] udp_tunnel6_xmit_skb+0x68d/0xb30 net/ipv6/ip6_udp_tunnel.c:112 tipc_udp_xmit+0x4f2/0xb60 net/tipc/udp_media.c:220 tipc_udp_send_msg+0x27f/0x3f0 net/tipc/udp_media.c:271 tipc_bearer_xmit_skb+0x2b3/0x400 net/tipc/bearer.c:575 tipc_disc_timeout+0x580/0x6d0 net/tipc/discover.c:338 call_timer_fn+0x16e/0x590 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2373 [inline] __run_timer_base+0x61a/0x860 kernel/time/timer.c:2385 run_timer_base kernel/time/timer.c:2394 [inline] run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2404 handle_softirqs+0x27d/0x850 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:723 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82 Code: d3 ec 02 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 53 cd 19 00 f3 0f 1e fa fb f4 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffffff8dc07d80 EFLAGS: 000002c6 RAX: 1ccece5e5b9a3f00 RBX: ffffffff81973b4a RCX: 1ccece5e5b9a3f00 RDX: 0000000000000001 RSI: ffffffff8d781ac2 RDI: ffffffff8bc006e0 RBP: ffffffff8dc07ea8 R08: ffff8880b883359b R09: 1ffff110171066b3 R10: dffffc0000000000 R11: ffffed10171066b4 R12: ffffffff8f814270 R13: 1ffffffff1b92a50 R14: 0000000000000000 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:767 default_idle_call+0x73/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:191 [inline] do_idle+0x1ea/0x520 kernel/sched/idle.c:332 cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:430 rest_init+0x2de/0x300 init/main.c:757 start_kernel+0x3ae/0x410 init/main.c:1111 x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310 x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291 common_startup_64+0x13e/0x147 GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog net_ratelimit: 13 callbacks suppressed GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog