INFO: task syz.5.556:8256 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.5.556       state:D stack:26880 pid:8256  tgid:8255  ppid:7830   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7bf/0x1550
 sync_bdevs+0x276/0x470
 __ia32_sys_sync+0xc5/0x120
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2c6739e0d9
RSP: 002b:00007f2c682f9028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f2c67625fa0 RCX: 00007f2c6739e0d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f2c67625fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2c67626038 R14: 00007f2c67625fa0 R15: 00007ffce71fafe8
 </TASK>
INFO: task syz.5.556:8259 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.5.556       state:D stack:28552 pid:8259  tgid:8255  ppid:7830   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7bf/0x1550
 sync_bdevs+0x276/0x470
 __ia32_sys_sync+0xc5/0x120
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2c6739e0d9
RSP: 002b:00007f2c682d8028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f2c67626090 RCX: 00007f2c6739e0d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f2c67626090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2c67626128 R14: 00007f2c67626090 R15: 00007ffce71fafe8
 </TASK>
INFO: task syz.5.556:8260 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.5.556       state:D stack:28552 pid:8260  tgid:8255  ppid:7830   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7bf/0x1550
 sync_bdevs+0x276/0x470
 __ia32_sys_sync+0xc5/0x120
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2c6739e0d9
RSP: 002b:00007f2c682b7028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f2c67626180 RCX: 00007f2c6739e0d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f2c67626180 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2c67626218 R14: 00007f2c67626180 R15: 00007ffce71fafe8
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/0:0/9:
 #0: ffff8881681dd140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc900000e7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff8881067721d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30
1 lock held by khungtaskd/34:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
6 locks held by kworker/u10:4/65:
2 locks held by getty/5427:
 #0: ffff8881109330a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034732e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
1 lock held by udevd/5601:
 #0: ffff88816d1f2350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
1 lock held by syz.5.556/8256:
 #0: ffff88816d1f2350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x276/0x470
1 lock held by syz.5.556/8259:
 #0: ffff88816d1f2350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x276/0x470
1 lock held by syz.5.556/8260:
 #0: ffff88816d1f2350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x276/0x470
2 locks held by iou-wrk-12434/12451:

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

NMI backtrace for cpu 0
CPU: 0 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/0x380
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 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: 6289 Comm: kworker/u9:7 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
Workqueue: events_unbound nsim_dev_trap_report_work
RIP: 0010:unwind_next_frame+0xba9/0x2550
Code: ff df 48 8b 4c 24 10 0f b6 04 01 84 c0 0f 85 3b 14 00 00 41 83 3e 00 0f 95 c0 49 39 d7 0f 96 c1 20 c1 49 39 d5 0f 97 c0 20 c8 <3c> 01 75 18 48 8d 42 08 4c 39 f8 0f 97 c1 4c 39 e8 0f 96 c0 84 c1
RSP: 0018:ffffc90000a08960 EFLAGS: 00000202
RAX: 0000000000000001 RBX: 1ffff92000141142 RCX: 1ffff92000141101
RDX: ffffc90000a08f50 RSI: 0000000000000002 RDI: ffffc90000a08a18
RBP: 1ffffffff21e529b R08: ffffc90000a08f58 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb59c60 R12: 1ffff92000141143
R13: ffffc90000a09000 R14: ffffc90000a08a08 R15: ffffc90000a01000
FS:  0000000000000000(0000) GS:ffff8882a8f54000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f68f27f0078 CR3: 000000011cc74000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 arch_stack_walk+0x11b/0x150
 stack_trace_save+0xa9/0x100
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x40/0x50
 __kasan_slab_free+0x5c/0x80
 slab_free_after_rcu_debug+0x12a/0x220
 rcu_core+0x78b/0x10a0
 handle_softirqs+0x225/0x840
 do_softirq+0x76/0xd0
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0xf8/0x130
 nsim_dev_trap_report_work+0x7a4/0xb40
 process_scheduled_works+0xa8e/0x14e0
 worker_thread+0xa47/0xfb0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
