INFO: task syz.7.3978:16607 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.7.3978      state:D stack:27592 pid:16607 tgid:16606 ppid:11216  task_flags:0x400040 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: 0033:0x7f10f3b9cdd9
RSP: 002b:00007f10f49d6028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f10f3e15fa0 RCX: 00007f10f3b9cdd9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f10f3e15fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f10f3e16038 R14: 00007f10f3e15fa0 R15: 00007ffc3d554478
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/0:1/10:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc900000f7c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffff8881b958a230 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x202/0x3d0
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/5438:
 #0: ffff8881140600a0 (&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/5618:
 #0: ffff888103baf350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
5 locks held by syz.1.3267/14856:
1 lock held by syz.7.3978/16607:
 #0: ffff888103baf350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
1 lock held by syz.9.5233/19678:
 #0: ffff888103baf350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
1 lock held by syz.9.5233/19681:
 #0: ffff888103baf350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
1 lock held by syz.9.5233/19684:
 #0: ffff888103baf350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
1 lock held by syz.9.5233/19687:
 #0: ffff888103baf350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
1 lock held by syz.9.5233/19690:
 #0: ffff888103baf350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
1 lock held by syz.9.5233/19691:
 #0: ffff888103baf350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
1 lock held by syz.9.5233/19692:
 #0: ffff888103baf350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
1 lock held by syz.9.5233/19693:
 #0: ffff888103baf350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x27e/0x470
3 locks held by kworker/0:6/20144:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc90006807c40 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffffffff8e9630a8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
1 lock held by syz.0.5430/20232:
 #0: ffffffff8e9630a8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770
1 lock held by syz.6.5435/20241:
 #0: ffffffff8fdd0380 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0
2 locks held by udevadm/20245:

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

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/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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: kcompactd0 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: 0010:psi_task_switch+0x43f/0x880
Code: 49 81 c7 90 13 00 00 4c 89 f8 48 c1 e8 03 0f b6 04 10 84 c0 4c 8b 74 24 10 0f 85 46 03 00 00 41 33 1f f7 c3 ef ff ff ff 74 53 <48> 85 ed 74 4e 41 83 e5 0c 0f b6 5c 24 1c eb 09 48 8b 6d 00 48 85
RSP: 0018:ffffc90000ae7720 EFLAGS: 00000002
RAX: 0000000000000000 RBX: 0000000000000014 RCX: 0000000080000001
RDX: dffffc0000000000 RSI: ffffffff8e218de6 RDI: ffffffff8c28b5e0
RBP: ffffffff8e81f280 R08: ffff8881032f1d80 R09: ffff88823c624588
R10: dffffc0000000000 R11: ffffed102065e3b1 R12: 0000000000000000
R13: 0000000000000014 R14: 0000000000000001 R15: ffff88819c034e90
FS:  0000000000000000(0000) GS:ffff8882a9290000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056239decfa88 CR3: 00000001bb838000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __schedule+0x29ae/0x5680
 schedule+0x164/0x360
 schedule_timeout+0x158/0x2c0
 kcompactd+0x416/0x12e0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
