INFO: task syz.8.449:9424 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.8.449       state:D stack:23752 pid:9424  tgid:9423  ppid:8809   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x1821/0x5740
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_read_slowpath+0x6d9/0x940
 down_read+0x99/0x2e0
 super_lock+0x2d6/0x3d0
 __iterate_supers+0x126/0x250
 __se_sys_quotactl+0x3a7/0x9e0
 do_syscall_64+0x15f/0x560
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f61dbd9ce59
RSP: 002b:00007f61d9ff6028 EFLAGS: 00000246 ORIG_RAX: 00000000000000b3
RAX: ffffffffffffffda RBX: 00007f61dc015fa0 RCX: 00007f61dbd9ce59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff80000101
RBP: 00007f61dbe32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f61dc016038 R14: 00007f61dc015fa0 R15: 00007ffd4a57d7c8
 </TASK>
INFO: task syz.9.453:9463 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.9.453       state:D stack:24696 pid:9463  tgid:9462  ppid:9139   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x1821/0x5740
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_read_slowpath+0x6d9/0x940
 down_read+0x99/0x2e0
 super_lock+0x2d6/0x3d0
 __iterate_supers+0x126/0x250
 __ia32_sys_sync+0xa0/0x120
 do_syscall_64+0x15f/0x560
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdb5159ce59
RSP: 002b:00007fdb523a9028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fdb51815fa0 RCX: 00007fdb5159ce59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fdb51815fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdb51816038 R14: 00007fdb51815fa0 R15: 00007ffc8a60a578
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e95cce0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
4 locks held by kworker/u10:9/1204:
 #0: ffff8881000ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc90007987c40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffffffff8fdd1b00 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60
 #3: ffffffff8e962fe8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
2 locks held by getty/5444:
 #0: ffff888112ddc0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034762e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0
2 locks held by syz-executor/8051:
1 lock held by syz.8.449/9424:
 #0: ffff88811d5740d8 (&type->s_umount_key#55){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz.9.453/9463:
 #0: ffff88811d5740d8 (&type->s_umount_key#55){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
2 locks held by syz.2.550/10378:
 #0: ffff8881092e0410 (sb_writers#3){.+.+}-{0:0}, at: direct_splice_actor+0x49/0x160
 #1: ffff88811d5740d8 (&type->s_umount_key#55){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
2 locks held by syz.0.583/10629:
 #0: ffff888111a24410 (sb_writers#3){.+.+}-{0:0}, at: vfs_write+0x227/0xb90
 #1: ffff88811d5740d8 (&type->s_umount_key#55){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz.5.624/11219:
 #0: ffff88811d5740d8 (&type->s_umount_key#55){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz.6.630/11359:
 #0: ffff88811d5740d8 (&type->s_umount_key#55){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
2 locks held by syz.7.797/12516:
 #0: ffff8881a7714410 (sb_writers#3){.+.+}-{0:0}, at: vfs_write+0x227/0xb90
 #1: ffff88811d5740d8 (&type->s_umount_key#55){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
7 locks held by syz-executor/12738:
 #0: ffff888113946410 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x227/0xb90
 #1: ffff88811ccc1880 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1de/0x540
 #2: ffff88816b9d0e18 (kn->active#48){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x231/0x540
 #3: ffffffff8f650800 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd7/0x370
 #4: ffff88816cfe8128 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb6/0x870
 #5: ffff8881bbfd0258 (&devlink->lock_key#14){+.+.}-{4:4}, at: nsim_drv_remove+0x50/0x170
 #6: ffffffff8fdd1b00 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_dev_lock+0x257/0x2f0
5 locks held by syz.8.850/12764:
 #0: ffff8881ae27cea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x212/0x5a0
 #1: ffff8881ae27c0b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x640/0x10e0
 #2: ffffffff8ff55260 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xa1/0x260
 #3: ffff888116b8eaf8 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x92/0x570
 #4: ffffffff8e962fe8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770

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

NMI backtrace for cpu 0
CPU: 0 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+0xfd3/0x1030
 kthread+0x389/0x470
 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: 5624 Comm: kworker/u11:4 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: hci10 hci_cmd_timeout
RIP: 0010:io_serial_in+0x77/0xc0
Code: e8 fe 9d 80 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 5f e1 eb 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:ffffc900068b73f0 EFLAGS: 00000002
RAX: 1ffffffff34f5160 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020
RBP: ffffffff9a7a8b10 R08: ffff888109ca0237 R09: 1ffff11021394046
R10: dffffc0000000000 R11: ffffffff854517a0 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff9a7a8880 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8882a9287000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005610c6a14131 CR3: 000000016c232000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 wait_for_lsr+0xd1/0x2f0
 serial8250_console_write+0x1348/0x1ba0
 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+0xb5d/0x1860
 worker_thread+0xa53/0xfc0
 kthread+0x389/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
