INFO: task kworker/0:4:373 blocked for more than 125 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/0:4 state:D stack:0 pid:373 tgid:373 ppid:2 flags:0x00004000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:6016 [inline] __schedule+0x1399/0x1fa0 kernel/sched/core.c:7870 __schedule_loop kernel/sched/core.c:7951 [inline] schedule+0xc5/0x240 kernel/sched/core.c:7966 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:8023 __mutex_lock_common kernel/locking/mutex.c:707 [inline] __mutex_lock+0x960/0x1bb0 kernel/locking/mutex.c:803 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1134 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285 rcu_barrier+0x4d/0x540 kernel/rcu/tree.c:4589 netdev_run_todo+0x118/0xce0 net/core/dev.c:10887 rtnl_unlock+0x12/0x20 net/core/rtnetlink.c:152 unregister_netdev+0x166/0x1d0 net/core/dev.c:11589 usbnet_disconnect+0xd5/0x3a0 drivers/net/usb/usbnet.c:1653 usb_unbind_interface+0x2aa/0xa30 drivers/usb/core/driver.c:462 device_remove drivers/base/dd.c:569 [inline] __device_release_driver drivers/base/dd.c:1272 [inline] device_release_driver_internal+0x4c2/0x790 drivers/base/dd.c:1295 device_release_driver+0x1d/0x30 drivers/base/dd.c:1318 bus_remove_device+0x359/0x380 drivers/base/bus.c:576 device_del+0x581/0xd00 drivers/base/core.c:3881 usb_disable_device+0x3af/0x770 drivers/usb/core/message.c:1418 usb_disconnect+0x322/0x930 drivers/usb/core/hub.c:2353 hub_port_connect drivers/usb/core/hub.c:5414 [inline] hub_port_connect_change drivers/usb/core/hub.c:5714 [inline] port_event drivers/usb/core/hub.c:5878 [inline] hub_event+0x1c7a/0x4700 drivers/usb/core/hub.c:5960 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0x7d1/0x1020 kernel/workqueue.c:3319 worker_thread+0xc70/0x10b0 kernel/workqueue.c:3400 kthread+0x2c9/0x370 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 Not tainted syzkaller #0 e5e4876e63e0994bd4350cd5f958f668e2098f7e Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 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+0xdad/0xf00 kernel/hung_task.c:423 kthread+0x2c9/0x370 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: 33 Comm: rcuop/1 Not tainted syzkaller #0 e5e4876e63e0994bd4350cd5f958f668e2098f7e Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:bcmp+0x22a/0x240 lib/string.c:704 Code: 89 7d c8 48 89 cf 49 89 d4 49 89 f6 41 89 c5 e8 7c af 42 fc 44 89 e8 48 8b 7d c8 4c 89 f6 4c 89 e2 eb 96 31 c0 48 83 c4 10 5b <41> 5c 41 5d 41 5e 41 5f 5d e9 08 3b 06 00 cc 0f 1f 80 00 00 00 00 RSP: 0018:ffffc90000230550 EFLAGS: 00000286 RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffc90000230608 RDI: ffff888106313018 RBP: ffffc90000230570 R08: 000000001baaaaaa R09: 1ffff920000460c0 R10: dffffc0000000000 R11: fffff520000460c1 R12: 00001baaaaaaaaaa R13: 0000000000000000 R14: ffff888106313018 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6535345000 CR3: 0000000125b76000 CR4: 00000000003526b0 Call Trace: memcmp include/linux/fortify-string.h:715 [inline] rhashtable_compare include/linux/rhashtable.h:585 [inline] __rhashtable_lookup include/linux/rhashtable.h:610 [inline] rhashtable_lookup include/linux/rhashtable.h:646 [inline] fdb_find_rcu+0x2cb/0x540 net/bridge/br_fdb.c:223 br_fdb_update+0x109/0x680 net/bridge/br_fdb.c:903 br_handle_frame_finish+0x3a3/0x1760 net/bridge/br_input.c:141 nf_hook_bridge_pre net/bridge/br_input.c:301 [inline] br_handle_frame+0x5a6/0xba0 net/bridge/br_input.c:424 __netif_receive_skb_core+0xfb1/0x3ab0 net/core/dev.c:5670 __netif_receive_skb_one_core net/core/dev.c:5774 [inline] __netif_receive_skb net/core/dev.c:5889 [inline] process_backlog+0x3e5/0xad0 net/core/dev.c:6225 __napi_poll+0xd0/0x610 net/core/dev.c:6876 napi_poll net/core/dev.c:6945 [inline] net_rx_action+0x5ea/0xd80 net/core/dev.c:7067 handle_softirqs+0x1ad/0x630 kernel/softirq.c:621 __do_softirq+0xf/0x16 kernel/softirq.c:659 do_softirq+0xb8/0x110 kernel/softirq.c:503 __local_bh_enable_ip+0x74/0x80 kernel/softirq.c:430 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_do_batch+0x5d9/0xd40 kernel/rcu/tree.c:2594 nocb_cb_wait kernel/rcu/tree_nocb.h:923 [inline] rcu_nocb_cb_kthread+0x524/0xb30 kernel/rcu/tree_nocb.h:957 kthread+0x2c9/0x370 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 net_ratelimit: 110494 callbacks suppressed bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:92:e2:38:7e:ad:41, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0) net_ratelimit: 129988 callbacks suppressed bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0) bridge0: received packet on veth1_to_bridge with own address as source address (addr:92:e2:38:7e:ad:41, vlan:0) bridge0: received packet on bridge_slave_1 with own address as source address (addr:aa:aa:aa:aa:aa:1c, vlan:0)