INFO: task kworker/1:0:24 blocked for more than 143 seconds. Not tainted 6.16.0-rc4-next-20250630-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/1:0 state:D stack:20696 pid:24 tgid:24 ppid:2 task_flags:0x4288160 flags:0x00004000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:5313 [inline] __schedule+0x16f5/0x4d00 kernel/sched/core.c:6696 __schedule_loop kernel/sched/core.c:6774 [inline] schedule+0x165/0x360 kernel/sched/core.c:6789 schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75 do_wait_for_common kernel/sched/completion.c:100 [inline] __wait_for_common kernel/sched/completion.c:121 [inline] wait_for_common kernel/sched/completion.c:132 [inline] wait_for_completion+0x2bf/0x5d0 kernel/sched/completion.c:153 __flush_work+0x9b9/0xbc0 kernel/workqueue.c:4247 flush_work kernel/workqueue.c:4268 [inline] flush_delayed_work+0x13e/0x190 kernel/workqueue.c:4290 hub_quiesce+0x1f0/0x330 drivers/usb/core/hub.c:1421 hub_disconnect+0xc8/0x470 drivers/usb/core/hub.c:1821 usb_unbind_interface+0x26b/0x910 drivers/usb/core/driver.c:458 device_remove drivers/base/dd.c:569 [inline] __device_release_driver drivers/base/dd.c:1272 [inline] device_release_driver_internal+0x4d6/0x7c0 drivers/base/dd.c:1295 bus_remove_device+0x34d/0x410 drivers/base/bus.c:579 device_del+0x511/0x8e0 drivers/base/core.c:3880 usb_disable_device+0x3e9/0x8a0 drivers/usb/core/message.c:1418 usb_disconnect+0x330/0x950 drivers/usb/core/hub.c:2349 hub_port_connect drivers/usb/core/hub.c:5411 [inline] hub_port_connect_change drivers/usb/core/hub.c:5711 [inline] port_event drivers/usb/core/hub.c:5871 [inline] hub_event+0x1cdb/0x4a00 drivers/usb/core/hub.c:5953 process_one_work kernel/workqueue.c:3239 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3322 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3403 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 INFO: task kworker/1:6:5924 blocked for more than 143 seconds. Not tainted 6.16.0-rc4-next-20250630-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/1:6 state:D stack:21480 pid:5924 tgid:5924 ppid:2 task_flags:0x4208060 flags:0x00004000 Workqueue: events_power_efficient hub_init_func2 Call Trace: context_switch kernel/sched/core.c:5313 [inline] __schedule+0x16f5/0x4d00 kernel/sched/core.c:6696 __schedule_loop kernel/sched/core.c:6774 [inline] schedule+0x165/0x360 kernel/sched/core.c:6789 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6846 __mutex_lock_common kernel/locking/mutex.c:679 [inline] __mutex_lock+0x724/0xe80 kernel/locking/mutex.c:747 device_lock include/linux/device.h:884 [inline] hub_activate+0xb7/0x1ea0 drivers/usb/core/hub.c:1096 process_one_work kernel/workqueue.c:3239 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3322 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3403 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Showing all locks held in the system: 5 locks held by kworker/1:0/24: #0: ffff8881446f1148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline] #0: ffff8881446f1148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3322 #1: ffffc900001e7bc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3215 [inline] #1: ffffc900001e7bc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3322 #2: ffff888028143198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:884 [inline] #2: ffff888028143198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a00 drivers/usb/core/hub.c:5899 #3: ffff88802452f198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:884 [inline] #3: ffff88802452f198 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0xf8/0x950 drivers/usb/core/hub.c:2340 #4: ffff88807ebb5160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:884 [inline] #4: ffff88807ebb5160 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1094 [inline] #4: ffff88807ebb5160 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb6/0x7c0 drivers/base/dd.c:1292 1 lock held by khungtaskd/31: #0: ffffffff8e33bee0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8e33bee0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #0: ffffffff8e33bee0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6770 5 locks held by kworker/1:2/120: #0: ffff8881446f1148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline] #0: ffff8881446f1148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3322 #1: ffffc900026b7bc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3215 [inline] #1: ffffc900026b7bc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3322 #2: ffff8880284f3198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:884 [inline] #2: ffff8880284f3198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a00 drivers/usb/core/hub.c:5899 #3: ffff8880284f6510 (&port_dev->status_lock){+.+.}-{4:4}, at: usb_lock_port drivers/usb/core/hub.c:3256 [inline] #3: ffff8880284f6510 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5468 [inline] #3: ffff8880284f6510 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5711 [inline] #3: ffff8880284f6510 (&port_dev->status_lock){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5871 [inline] #3: ffff8880284f6510 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x21a3/0x4a00 drivers/usb/core/hub.c:5953 #4: ffff8880284be468 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect drivers/usb/core/hub.c:5469 [inline] #4: ffff8880284be468 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_port_connect_change drivers/usb/core/hub.c:5711 [inline] #4: ffff8880284be468 (hcd->address0_mutex){+.+.}-{4:4}, at: port_event drivers/usb/core/hub.c:5871 [inline] #4: ffff8880284be468 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x21cb/0x4a00 drivers/usb/core/hub.c:5953 1 lock held by udevd/5207: 2 locks held by getty/5597: #0: ffff88814d12e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc900036b32f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222 3 locks held by kworker/1:6/5924: #0: ffff88801a882148 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline] #0: ffff88801a882148 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3322 #1: ffffc9000aa3fbc0 ((work_completion)(&(&hub->init_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3215 [inline] #1: ffffc9000aa3fbc0 ((work_completion)(&(&hub->init_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3322 #2: ffff88802452f198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:884 [inline] #2: ffff88802452f198 (&dev->mutex){....}-{4:4}, at: hub_activate+0xb7/0x1ea0 drivers/usb/core/hub.c:1096 6 locks held by kworker/0:1/12520: #0: ffff8881446f1148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline] #0: ffff8881446f1148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3322 #1: ffffc90003757bc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3215 [inline] #1: ffffc90003757bc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3322 #2: ffff888144bdd198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:884 [inline] #2: ffff888144bdd198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a00 drivers/usb/core/hub.c:5899 #3: ffff88807b80d198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:884 [inline] #3: ffff88807b80d198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400 drivers/base/dd.c:1004 #4: ffff88807c1b4160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:884 [inline] #4: ffff88807c1b4160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400 drivers/base/dd.c:1004 #5: ffff88805ffc5c18 (&dev->ctrl_urb_lock){+.+.}-{4:4}, at: em28xx_write_regs_req+0x14d/0x3e0 drivers/media/usb/em28xx/em28xx-core.c:147 3 locks held by syz.2.5135/20053: 1 lock held by syz.6.5144/20082: 1 lock held by syz.5.5145/20080: #0: ffffffff8e3418c0 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x570 kernel/rcu/tree.c:3792 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.16.0-rc4-next-20250630-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 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: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:463 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 20053 Comm: syz.2.5135 Not tainted 6.16.0-rc4-next-20250630-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240 Code: 8d e8 2b ca e5 ff 90 0f 0b 90 90 90 31 c0 48 8b 3c 24 48 83 78 40 00 0f 84 6a 01 00 00 4c 89 f6 89 ea 4c 89 f9 e8 17 38 00 00 <85> c0 0f 84 e4 01 00 00 41 f6 46 22 10 75 2e 48 8b 1c 24 4c 89 bb RSP: 0018:ffffc90000007688 EFLAGS: 00000086 RAX: 0000000000000001 RBX: 0000000000000003 RCX: 0a24dbaafeabd000 RDX: 0000000000000000 RSI: ffff888058656568 RDI: ffff888058655a00 RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8172dc65 R10: ffffc900000078d8 R11: ffffffff81acb300 R12: 00000000762cb430 R13: ffff8880586564f0 R14: ffff888058656568 R15: 8254f670159718c0 FS: 000055556bb42500(0000) GS:ffff8881259e4000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f81ddee8e9c CR3: 0000000033790000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000f6e DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 rcu_lock_acquire include/linux/rcupdate.h:331 [inline] rcu_read_lock include/linux/rcupdate.h:841 [inline] class_rcu_constructor include/linux/rcupdate.h:1155 [inline] unwind_next_frame+0xc2/0x2390 arch/x86/kernel/unwind_orc.c:479 arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2417 [inline] slab_free mm/slub.c:4680 [inline] kmem_cache_free+0x18f/0x400 mm/slub.c:4782 rcu_do_batch kernel/rcu/tree.c:2582 [inline] rcu_core+0xca8/0x1710 kernel/rcu/tree.c:2838 handle_softirqs+0x286/0x870 kernel/softirq.c:579 do_softirq+0xec/0x180 kernel/softirq.c:480 __local_bh_enable_ip+0x17d/0x1c0 kernel/softirq.c:407 pneigh_ifdown_and_unlock net/core/neighbour.c:828 [inline] __neigh_ifdown+0x238/0x470 net/core/neighbour.c:427 neigh_ifdown+0x1f/0x30 net/core/neighbour.c:444 fib_netdev_event+0x8c/0x490 net/ipv4/fib_frontend.c:1503 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline] call_netdevice_notifiers net/core/dev.c:2282 [inline] unregister_netdevice_many_notify+0x15d8/0x2320 net/core/dev.c:12118 unregister_netdevice_many net/core/dev.c:12181 [inline] unregister_netdevice_queue+0x33c/0x380 net/core/dev.c:12025 unregister_netdevice include/linux/netdevice.h:3382 [inline] unregister_netdev+0x1f/0x60 net/core/dev.c:12199 mkiss_close+0x1d8/0x2a0 drivers/net/hamradio/mkiss.c:797 tty_ldisc_kill+0xa3/0x1a0 drivers/tty/tty_ldisc.c:613 tty_ldisc_release+0x174/0x200 drivers/tty/tty_ldisc.c:781 tty_release_struct+0x2a/0xd0 drivers/tty/tty_io.c:1681 tty_release+0xcb0/0x1640 drivers/tty/tty_io.c:1852 __fput+0x449/0xa70 fs/file_table.c:468 task_work_run+0x1d1/0x260 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:114 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline] do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff8d2d8e929 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff84f438c8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007ff8d2fb7ba0 RCX: 00007ff8d2d8e929 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007ff8d2fb7ba0 R08: 00000000000001f4 R09: 0000001984f43bbf R10: 00000000003ffbe4 R11: 0000000000000246 R12: 00000000000ae1c3 R13: 00007ff8d2fb6080 R14: ffffffffffffffff R15: 00007fff84f439e0