INFO: task syz.8.434:14696 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.8.434       state:D stack:26240 pid:14696 tgid:14694 ppid:13257  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x1585/0x5340
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_read_slowpath+0x61e/0x920
 down_read+0x99/0x2e0
 super_lock+0x2d6/0x3d0
 __iterate_supers+0x126/0x290
 __se_sys_quotactl+0x3a7/0x9e0
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f775199c799
RSP: 002b:00007f77527d0028 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007f7751c15fa0 RCX: 00007f775199c799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff80000100
RBP: 00007f7751a32bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7751c16038 R14: 00007f7751c15fa0 R15: 00007fffbfd59cf8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e7602e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5635:
 #0: ffff888174de60a0 (&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
3 locks held by kworker/0:10/7044:
 #0: ffff88810006b548 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830
 #1: ffffc90003e57c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830
 #2: ffff888113590240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x202/0x3d0
2 locks held by syz-executor/9085:
1 lock held by syz.8.434/14696:
 #0: ffff8881136060e0 (&type->s_umount_key#56){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz.5.620/18045:
 #0: ffff8881136060e0 (&type->s_umount_key#56){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz.9.699/19435:
 #0: ffff8881136060e0 (&type->s_umount_key#56){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz-executor/20866:
 #0: ffffffff8e766578 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770
2 locks held by syz.2.891/23488:
2 locks held by dhcpcd-run-hook/23521:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 34 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
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+0xfd9/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 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: 5198 Comm: kworker/u11:1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: hci2 hci_cmd_timeout
RIP: 0010:io_serial_in+0x77/0xc0
Code: e8 8e 97 85 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 bf bc ef fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 cc cc cc cc cc 44 89 f9 80 e1 07
RSP: 0018:ffffc90009ebf478 EFLAGS: 00000006
RAX: 1ffffffff34b9505 RBX: 00000000000003f9 RCX: 0000000000000000
RDX: 00000000000003f9 RSI: 0000000000000000 RDI: 0000000000000020
RBP: ffffc90009ebf610 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff853ff3a0 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff9a5ca960 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88818de64000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff75190048 CR3: 0000000114c2a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 serial8250_console_write+0x540/0x1ba0
 console_flush_all+0x718/0xb20
 console_unlock+0xd1/0x1c0
 vprintk_emit+0x485/0x560
 _printk+0xdd/0x130
 bt_err+0x121/0x180
 hci_cmd_timeout+0xff/0x1e0
 process_scheduled_works+0xb02/0x1830
 worker_thread+0xa50/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30
 </TASK>
