INFO: task syz.8.5133:18947 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.8.5133      state:D stack:27696 pid:18947 tgid:18946 ppid:14829  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x14ef/0x4fb0
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7fe/0x1300
 sync_bdevs+0x27e/0x470
 __ia32_sys_sync+0xc5/0x120
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2b3379acb9
RSP: 002b:00007f2b3461e028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f2b33a15fa0 RCX: 00007f2b3379acb9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f2b33a15fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2b33a16038 R14: 00007f2b33a15fa0 R15: 00007ffed4dd47a8
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/1:1/33:
 #0: ffff8881042be148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0
 #1: ffffc90000a97bc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0
 #2: ffff88816f3b5198 (&dev->mutex){....}-{4:4}, at: hub_event+0x17f/0x4f30
 #3: ffff8881b008f198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450
 #4: ffff88816f21d160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450
1 lock held by khungtaskd/35:
 #0: ffffffff8e35a360 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5659:
 #0: ffff888113afe0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000356e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0
1 lock held by udevd/5915:
 #0: ffff88816c44a358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
1 lock held by udevd/7189:
1 lock held by syz.8.5133/18947:
 #0: ffff88816c44a358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
3 locks held by syz.9.6880/23525:

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 35 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 sys_info+0x135/0x170
 watchdog+0xf90/0xfe0
 kthread+0x726/0x8b0
 ret_from_fork+0x51b/0xa40
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 23525 Comm: syz.9.6880 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0033:0x7f6f73e6b26d
Code: 08 48 83 c3 08 48 39 d1 72 f3 48 8d 46 f8 48 8b 76 f8 48 39 f2 73 13 66 0f 1f 44 00 00 48 8b 70 f8 48 83 e8 08 48 39 f2 72 f3 <48> 39 c3 73 3e 48 89 33 48 89 c6 48 83 c3 08 48 89 08 48 8b 0b 48
RSP: 002b:00007ffcb75eecb0 EFLAGS: 00000246
RAX: 00007f6f73c0eb18 RBX: 00007f6f73c0eaa0 RCX: ffffffff8212075b
RDX: ffffffff8212075b RSI: ffffffff8212075b RDI: 00007f6f73c0ead8
RBP: 00007f6f73c0e808 R08: 0000000000000000 R09: 00007f6f74216038
R10: 0000000000000003 R11: 0000000000000000 R12: 00007f6f73c0edb0
R13: 0000000000000015 R14: 00000000000000b5 R15: 0000000000000003
FS:  000055555691f500 GS:  0000000000000000
