INFO: task kworker/0:0:9 blocked for more than 122 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:0 state:D stack:0 pid:9 tgid:9 ppid:2 flags:0x00004000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:6060 [inline] __schedule+0x1496/0x20b0 kernel/sched/core.c:7880 __schedule_loop kernel/sched/core.c:7957 [inline] schedule+0xc5/0x240 kernel/sched/core.c:7972 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:8029 __mutex_lock_common kernel/locking/mutex.c:707 [inline] __mutex_lock+0x902/0x1b90 kernel/locking/mutex.c:806 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1136 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285 usb_audio_probe+0x3c7/0x1dd0 sound/usb/card.c:887 usb_probe_interface+0x6a8/0xbf0 drivers/usb/core/driver.c:400 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x2e1/0x8b0 drivers/base/dd.c:657 __driver_probe_device+0x193/0x280 drivers/base/dd.c:799 driver_probe_device+0x54/0x3f0 drivers/base/dd.c:829 __device_attach_driver+0x2f1/0x4b0 drivers/base/dd.c:957 bus_for_each_drv+0x264/0x300 drivers/base/bus.c:459 __device_attach+0x2c4/0x3c0 drivers/base/dd.c:1029 device_initial_probe+0x1e/0x30 drivers/base/dd.c:1078 bus_probe_device+0x18b/0x270 drivers/base/bus.c:534 device_add+0x7fd/0xbf0 drivers/base/core.c:3692 usb_set_configuration+0x1aad/0x2080 drivers/usb/core/message.c:2268 usb_generic_driver_probe+0x95/0x160 drivers/usb/core/generic.c:254 usb_probe_device+0x1ef/0x3b0 drivers/usb/core/driver.c:295 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x2e1/0x8b0 drivers/base/dd.c:657 __driver_probe_device+0x193/0x280 drivers/base/dd.c:799 driver_probe_device+0x54/0x3f0 drivers/base/dd.c:829 __device_attach_driver+0x2f1/0x4b0 drivers/base/dd.c:957 bus_for_each_drv+0x264/0x300 drivers/base/bus.c:459 __device_attach+0x2c4/0x3c0 drivers/base/dd.c:1029 device_initial_probe+0x1e/0x30 drivers/base/dd.c:1078 bus_probe_device+0x18b/0x270 drivers/base/bus.c:534 device_add+0x7fd/0xbf0 drivers/base/core.c:3692 usb_new_device+0x98d/0x1500 drivers/usb/core/hub.c:2703 hub_port_connect drivers/usb/core/hub.c:5574 [inline] hub_port_connect_change drivers/usb/core/hub.c:5714 [inline] port_event drivers/usb/core/hub.c:5878 [inline] hub_event+0x2dbd/0x4360 drivers/usb/core/hub.c:5960 process_one_work kernel/workqueue.c:3273 [inline] process_scheduled_works+0x7f7/0x1060 kernel/workqueue.c:3354 worker_thread+0xc99/0x13f0 kernel/workqueue.c:3435 kthread+0x2c7/0x360 kernel/kthread.c:389 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Tainted: G W syzkaller #0 200dea8a17c83f35b0a1e1238c384757fc17b797 Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: __dump_stack+0x21/0x30 lib/dump_stack.c:94 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120 dump_stack+0x19/0x20 lib/dump_stack.c:129 nmi_cpu_backtrace+0x2ba/0x2d0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline] watchdog+0xe45/0xf90 kernel/hung_task.c:423 kthread+0x2c7/0x360 kernel/kthread.c:389 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 12 Comm: kworker/u8:0 Tainted: G W syzkaller #0 200dea8a17c83f35b0a1e1238c384757fc17b797 Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Workqueue: kvfree_rcu_reclaim kfree_rcu_work RIP: 0010:io_serial_in+0x7b/0xc0 drivers/tty/serial/8250/8250_port.c:406 Code: e8 1a 78 64 fe 44 89 f9 d3 e3 49 83 c6 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 eb 3a bd fe 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f 5d e9 05 15 83 02 cc 44 89 f9 80 e1 RSP: 0018:ffffc900002301f0 EFLAGS: 00000006 RAX: 1ffffffff1187205 RBX: 00000000000003f9 RCX: 0000000000000000 RDX: 00000000000003f9 RSI: 0000000000000000 RDI: 0000000000000020 RBP: ffffc90000230210 R08: 0000000000000003 R09: 0000000000000004 R10: 0000000000000000 R11: ffffffff8322f950 R12: dffffc0000000000 R13: ffffffff88bd9c60 R14: ffffffff88c39488 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f58771ec300 CR3: 00000000074aa000 CR4: 00000000003526b0 Call Trace: serial_port_in include/linux/serial_core.h:794 [inline] serial8250_console_write+0x326/0x2150 drivers/tty/serial/8250/8250_port.c:3391 univ8250_console_write+0x71/0xb0 drivers/tty/serial/8250/8250_core.c:396 console_emit_next_record kernel/printk/printk.c:3151 [inline] console_flush_all+0x5e6/0xab0 kernel/printk/printk.c:3239 __console_flush_and_unlock kernel/printk/printk.c:3298 [inline] console_unlock+0xf8/0x2c0 kernel/printk/printk.c:3338 vprintk_emit+0x282/0x650 kernel/printk/printk.c:2462 dev_vprintk_emit+0x33c/0x400 drivers/base/core.c:4962 dev_printk_emit+0xef/0x150 drivers/base/core.c:4973 __dev_printk+0x17f/0x1b0 drivers/base/core.c:4985 _dev_err+0x11f/0x180 drivers/base/core.c:5028 dummy_timer+0x4605/0x4900 drivers/usb/gadget/udc/dummy_hcd.c:1823 __run_hrtimer kernel/time/hrtimer.c:1757 [inline] __hrtimer_run_queues+0x3ae/0x8e0 kernel/time/hrtimer.c:1821 hrtimer_run_softirq+0x159/0x560 kernel/time/hrtimer.c:1838 handle_softirqs+0x1aa/0x620 kernel/softirq.c:621 __do_softirq kernel/softirq.c:659 [inline] invoke_softirq kernel/softirq.c:476 [inline] __irq_exit_rcu+0x47/0xb0 kernel/softirq.c:708 irq_exit_rcu+0xd/0x30 kernel/softirq.c:720 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0x82/0x90 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1f/0x30 arch/x86/include/asm/idtentry.h:702 RIP: 0010:__unwind_start+0x2fb/0x400 arch/x86/kernel/unwind_frame.c:416 Code: 75 65 48 8b 55 b8 4c 39 f2 0f 97 c1 48 39 c2 0f 96 c0 20 c8 3c 01 75 4f 48 b8 00 00 00 00 00 fc ff df 48 8b 4d c0 80 3c 01 00 <4c> 8d 73 50 74 08 4c 89 f7 e8 77 92 9b 00 49 83 3e 00 75 6b 48 b8 RSP: 0018:ffffc900000c7668 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ffffc900000c76c8 RCX: 1ffff92000018ee3 RDX: ffffc900000c7758 RSI: ffffc900000c76d8 RDI: ffffc900000c76f0 RBP: ffffc900000c76b8 R08: ffffc900000c7701 R09: 0000000000000000 R10: ffffc900000c76c8 R11: fffff52000018ee5 R12: 1ffff92000018edb R13: 1ffff92000018eda R14: ffffc900000c0000 R15: ffffc900000c76d8 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0xf2/0x170 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:49 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:70 kasan_save_free_info+0x44/0x50 mm/kasan/generic.c:579 poison_slab_object mm/kasan/common.c:249 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:266 kasan_slab_free include/linux/kasan.h:234 [inline] slab_free_hook mm/slub.c:2445 [inline] slab_free_freelist_hook mm/slub.c:2474 [inline] slab_free_bulk mm/slub.c:4744 [inline] kmem_cache_free_bulk+0x22c/0x540 mm/slub.c:4995 kfree_bulk include/linux/slab.h:770 [inline] kvfree_rcu_bulk+0x20f/0x4c0 kernel/rcu/tree.c:3399 kfree_rcu_work+0x321/0x390 kernel/rcu/tree.c:3478 process_one_work kernel/workqueue.c:3273 [inline] process_scheduled_works+0x7f7/0x1060 kernel/workqueue.c:3354 worker_thread+0xc99/0x13f0 kernel/workqueue.c:3435 kthread+0x2c7/0x360 kernel/kthread.c:389 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed dummy_hcd dummy_hcd.0: bogus device speed