INFO: task syz.6.678:9142 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.678       state:D stack:26904 pid:9142  tgid:9141  ppid:7464   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d4/0x5820
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 sync_bdevs+0x276/0x470
 __ia32_sys_sync+0xc5/0x120
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd49f59e159
RSP: 002b:00007fd4a050a028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd49f825fa0 RCX: 00007fd49f59e159
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd49f825fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd49f826038 R14: 00007fd49f825fa0 R15: 00007ffe47e6d9c8
 </TASK>

Showing all locks held in the system:
locks held by kworker/0:0/9: 3, on CPU#0:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900000e7c40 ((fqdir_free_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff8ed62938 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x530
locks held by pr/ttyS0/16: 2, last CPU#0:
 #0: ffffffff8ec36278 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60
 #1: ffffffff9ad250d8 (&port_lock_key){-.-.}-{3:3}, at: univ8250_console_device_lock+0x67/0xc0
locks held by khungtaskd/34: 1, last CPU#1:
 #0: ffffffff8ed5c6a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by getty/5416: 2, on CPU#0:
 #0: ffff888177b5a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034762e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
locks held by kworker/1:4/5645: 3, on CPU#1:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90004b4fc40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffff888179c15250 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1fd/0x3b0
locks held by udevd/5838: 1, on CPU#1:
 #0: ffff88816ca2b350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
locks held by kworker/u10:13/6654: 2, last CPU#1:
 #0: ffff88810fd14940 ((wq_completion)wg-kex-wg2#9){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900039afc40 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
locks held by kworker/1:8/8227: 3, on CPU#1:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90003c8fc40 (xfrm_state_gc_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff8ed62a68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
locks held by syz.6.678/9142: 1, on CPU#1:
 #0: ffff88816ca2b350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x276/0x470
locks held by syz.0.804/9995: 1, on CPU#1:
 #0: ffff88816ca2b350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
locks held by syz.0.804/9996: 2, on CPU#0:
 #0: ffff888105ae20e8 (&type->s_umount_key#52/1){+.+.}-{4:4}, at: sget_fc+0x97c/0x1a40
 #1: ffff88816ca2b350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
locks held by syz.0.1387/13687: 1, last CPU#0:
 #0: ffffffff8ed5c6a0 (rcu_read_lock){....}-{1:3}, at: bpf_test_timer_enter+0xf9/0x260
locks held by syz-executor/13695: 2, last CPU#1:
 #0: ffff88817a077408 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x1d1/0x500
 #1: ffffffff8ed5c6a0 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x240

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

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+0x17d/0x390
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x38b/0x480
 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: 16 Comm: pr/ttyS0 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:io_serial_out+0x7c/0xc0
Code: 52 57 fc 44 89 f9 d3 e5 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 4c 05 c7 fc 41 03 2e 89 d8 89 ea ee <5b> 41 5c 41 5e 41 5f 5d c3 cc cc cc cc cc 44 89 f9 80 e1 07 38 c1
RSP: 0018:ffffc90000157900 EFLAGS: 00000002
RAX: 0000000000000020 RBX: 0000000000000020 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000000003f8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff85705b30 R12: dffffc0000000000
R13: 0000000000000020 R14: ffffffff9ad25100 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88818d6e6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3fecc8 CR3: 00000001a150a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __serial8250_console_fifo_write+0x1e6/0x3e0
 serial8250_console_write+0xaa1/0x1200
 nbcon_emit_next_record+0xef5/0x1a90
 nbcon_kthread_func+0x679/0x880
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
