INFO: task syz.5.1866:6080 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.1866      state:D stack:0     pid:6080  tgid:6079  ppid:5672   flags:0x00000004
Call Trace:
 <TASK>
 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
 fdget_pos+0x24f/0x310 fs/file.c:1206
 ksys_read+0x7c/0x260 fs/read_write.c:704
 __do_sys_read fs/read_write.c:723 [inline]
 __se_sys_read fs/read_write.c:721 [inline]
 __x64_sys_read+0x7f/0x90 fs/read_write.c:721
 x64_sys_call+0x2638/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f9b1c99e0d9
RSP: 002b:00007f9b1d8c8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f9b1cc25fa0 RCX: 00007f9b1c99e0d9
RDX: 0000000000000023 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007f9b1ca35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9b1cc26038 R14: 00007f9b1cc25fa0 R15: 00007ffdc072eb08
 </TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 e678fb639bf2314ecbc0d819b692701f82417ebd
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 __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
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 1776 Comm: kworker/0:5 Not tainted syzkaller #0 e678fb639bf2314ecbc0d819b692701f82417ebd
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: usb_hub_wq hub_event
RIP: 0010:io_serial_in+0x7b/0xc0 drivers/tty/serial/8250/8250_port.c:406
Code: e8 1a 64 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 6b 28 bd fe 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f 5d e9 05 b1 83 02 cc 44 89 f9 80 e1
RSP: 0018:ffffc9000151eff0 EFLAGS: 00000006
RAX: 1ffffffff1187a05 RBX: 00000000000003f9 RCX: 0000000000000000
RDX: 00000000000003f9 RSI: 000000000001ccab RDI: 000000000001ccac
RBP: ffffc9000151f010 R08: 0000000000000003 R09: 0000000000000004
R10: 0000000000000000 R11: ffffffff83230d50 R12: dffffc0000000000
R13: ffffffff88bddc60 R14: ffffffff88c3d488 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001b00 CR3: 000000010af5e000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 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_info+0x11f/0x180 drivers/base/core.c:5031
 hub_port_init+0x1b38/0x2810 drivers/usb/core/hub.c:5003
 hub_port_connect drivers/usb/core/hub.c:5503 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5714 [inline]
 port_event drivers/usb/core/hub.c:5878 [inline]
 hub_event+0x2408/0x4360 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
 </TASK>