INFO: task syz.8.414:8230 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.8.414       state:D stack:27744 pid:8230  tgid:8228  ppid:8116   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 
 __schedule+0x17db/0x58f0
 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: 0033:0x7fb17579e159
RSP: 002b:00007fb176627028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fb175a26090 RCX: 00007fb17579e159
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fb175a26090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb175a26128 R14: 00007fb175a26090 R15: 00007ffe11c3b088
 </TASK>

Showing all locks held in the system:
locks held by pr/ttyS0/16: 2, last CPU#0:
 #0: ffffffff8ec367b8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60
 #1: ffffffff9ad3f098 (&port_lock_key){-.-.}-{3:3}, at: univ8250_console_device_lock+0x67/0xc0
locks held by khungtaskd/35: 1, last CPU#1:
 #0: ffffffff8ed5cbe0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by getty/5421: 2, on CPU#1:
 #0: ffff88817b27a0a0 (&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 udevd/5598: 1, on CPU#0:
 #0: ffff88816cdac350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
locks held by udevd/5811: 1, last CPU#1:
 #0: ffff88817ad58998 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xa4/0xca0
locks held by syz.8.414/8230: 1, on CPU#0:
 #0: ffff88816cdac350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x276/0x470
locks held by syz.0.584/9019: 1, on CPU#1:
 #0: ffff88816cdac350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
locks held by syz.2.1087/11291: 2, last CPU#1:
 #0: ffff88816c0260e8 (&type->s_umount_key#29/1){+.+.}-{4:4}, at: sget_fc+0x97c/0x1a40
 #1: ffffffff8ed5cbe0 (rcu_read_lock){....}-{1:3}, at: blk_mq_submit_bio+0x1c8d/0x2a70
locks held by syz.1.1090/11298: 2, last CPU#1:
 #0: ffff8881012fa460 (sb_writers#5){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #1: ffff888179420288 (&sb->s_type->i_mutex_key#15){++++}-{4:4}, at: shmem_file_write_iter+0x7f/0x120

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 35 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:_raw_spin_unlock+0x35/0x50
Code: 18 48 8b 74 24 08 e8 5a 3c bb f5 48 89 df e8 12 b4 bb f5 bf 01 00 00 00 e8 c8 cd ac f5 65 48 8b 05 c0 31 ad 07 48 85 c0 74 07 <5b> e9 c5 4a 00 00 cc e8 ff 56 4b f5 5b c3 cc cc cc cc cc 0f 1f 84
RSP: 0018:ffffc90000007d70 EFLAGS: 00000002
RAX: 0000000001000001 RBX: ffff88812103bcc8 RCX: ffffffff9a9e8501
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 00000000ffffffff
RBP: dffffc0000000000 R08: ffff88812103bccb R09: 1ffff11024207799
R10: dffffc0000000000 R11: ffffed102420779a R12: ffff888102ed8000
R13: ffffffff8e73ad90 R14: ffff88812103bcc8 R15: 1ffff1102420796c
FS:  0000000000000000(0000) GS:ffff88818d6cc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000011d0 CR3: 000000016b4d8000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 hrtick+0x1d3/0x2e0
 __hrtimer_run_queues+0x371/0xa10
 hrtimer_interrupt+0x4cd/0xaa0
 __sysvec_apic_timer_interrupt+0x102/0x430
 sysvec_apic_timer_interrupt+0xa1/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80
Code: f7 e8 ad b3 bb f5 f7 c3 00 02 00 00 74 05 e8 b0 f0 e7 f5 9c 58 a9 00 02 00 00 75 29 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 44 cd ac f5 65 48 8b 05 3c 31 ad 07 48 85 c0 74 18 5b 41 5e e9
RSP: 0018:ffffc90000157ca8 EFLAGS: 00000206
RAX: 0000000000000002 RBX: 0000000000000206 RCX: 8000000000000001
RDX: 0000000000000000 RSI: ffffffff8e47a1a9 RDI: 0000000000000001
RBP: ffffc90000157e18 R08: ffffffff907a5c7f R09: 1ffffffff20f4b8f
R10: dffffc0000000000 R11: fffffbfff20f4b90 R12: 0000000000000002
R13: ffff888102ed8000 R14: ffffffff9ad3f080 R15: dffffc0000000000
 nbcon_kthread_func+0x6c4/0x880
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
