INFO: task syz.1.5026:4966 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.1.5026      state:D stack:24696 pid:4966  tgid:4964  ppid:3107   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17b4/0x5680
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7f7/0x1550
 sync_bdevs+0x27e/0x470
 __ia32_sys_sync+0xc5/0x120
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0fe5b9cdd9
RSP: 002b:00007f0fe6b40028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f0fe5e15fa0 RCX: 00007f0fe5b9cdd9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f0fe5e15fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0fe5e16038 R14: 00007f0fe5e15fa0 R15: 00007ffd53483908
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/0:1/10:
 #0: ffff888105293540 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc900000f7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffff88816c9471d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x17f/0x4f30
 #3: ffff8881160281d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450
 #4: ffff88802a8c51a0 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450
1 lock held by khungtaskd/34:
 #0: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5436:
 #0: ffff888111a3c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000346b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0
1 lock held by udevd/6055:
 #0: ffff888169a3e350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
4 locks held by udevd/7279:
 #0: ffff88816d930f38 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xb7/0xe10
 #1: ffff88816d06d880 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x5c/0x420
 #2: ffff8881067092d8 (kn->active#23){++++}-{0:0}, at: kernfs_seq_start+0xb2/0x420
 #3: ffff8881160281d8 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0
1 lock held by syz.1.5026/4966:
 #0: ffff888169a3e350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
2 locks held by syz.7.6105/12603:
 #0: ffff88802bb28240 (&sb->s_type->i_mutex_key#13){+.+.}-{4:4}, at: sock_close+0x9b/0x240
 #1: ffffffff8e9630a8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 34 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+0xfd3/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5059 Comm: udevd 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: 0033:0x7f7c6f710e3e
Code: 13 00 48 89 84 24 f8 00 00 00 e8 fb 31 ff ff 4c 8b 64 24 48 85 c0 41 89 c5 79 0a 4c 89 e7 e8 f9 24 fc ff eb 70 48 8b 54 24 30 <48> 8b 6c 24 38 48 8b 44 24 40 48 29 d5 48 29 d0 48 8d 75 01 48 d1
RSP: 002b:00007ffcee7881c0 EFLAGS: 00000202
RAX: 000000000000002a RBX: 00007ffcee7883e0 RCX: 0000000000000001
RDX: 0000556ee7a36710 RSI: 0000556ecf3f41c9 RDI: 00007ffcee7881d0
RBP: 0000556ee7a36710 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000812 R11: 0000000000000000 R12: 0000556ee7a36710
R13: 000000000000002a R14: 00007ffcee788308 R15: 0000000000000000
FS:  00007f7c6f69cc80 GS:  0000000000000000
