INFO: task syz.8.4062:16154 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.8.4062      state:D stack:27696 pid:16154 tgid:16153 ppid:13788  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 cgroup_lock_and_drain_offline+0x51a/0x650
 cgroup1_get_tree+0x9d/0x890
 vfs_get_tree+0x92/0x2a0
 do_new_mount+0x319/0xdc0
 __se_sys_mount+0x31d/0x420
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff282f9e0d9
RSP: 002b:00007ff283dbc028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ff283225fa0 RCX: 00007ff282f9e0d9
RDX: 0000200000000580 RSI: 0000200000000540 RDI: 0000000000000000
RBP: 00007ff283035024 R08: 00002000000005c0 R09: 0000000000000000
R10: 0000000000200004 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff283226038 R14: 00007ff283225fa0 R15: 00007fff15acb178
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/35:
 #0: 
ffffffff8eb59c20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5428:
 #0: ffff8881145f30a0 (&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
3 locks held by kworker/1:5/5676:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc900068f7c40 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffffffff8eb5ff28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
2 locks held by syz.6.2947/13493:
3 locks held by syz.7.5569/19736:
 #0: ffff888101fca6f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320
 #1: ffff8881096fa450 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #2: 
ffff8880234b6c80 (
&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540
2 locks held by syz.1.5796/20451:
1 lock held by syz.2.5803/20472:

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

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+0x17a/0x380
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x388/0x470
 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: 13493 Comm: syz.6.2947 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: b1 5f 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 2c d1 cd 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:ffffc90004f9f0b0 EFLAGS: 00000002
RAX: 0000000000000035 RBX: 0000000000000035 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 000000000007ffff RDI: 0000000000080000
RBP: 00000000000003f8 R08: ffff888168a18237 R09: 1ffff1102d143046
R10: dffffc0000000000 R11: ffffffff85673620 R12: dffffc0000000000
R13: ffffffff9aace0c0 R14: ffffffff9aace100 R15: 0000000000000000
FS:  00007f46edd816c0(0000) GS:ffff88818d95d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe9326efe8 CR3: 000000016a0c8000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 serial8250_console_write+0x13b6/0x1ba0
 console_flush_all+0x6ea/0xaf0
 console_unlock+0xd1/0x1c0
 vprintk_emit+0x485/0x560
 _printk+0xdd/0x130
 __nilfs_msg+0x373/0x450
 nilfs_clean_segments+0x6f2/0xbb0
 nilfs_ioctl+0x2619/0x2780
 __se_sys_ioctl+0xfc/0x170
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f46ecf9e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f46edd81028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f46ed225fa0 RCX: 00007f46ecf9e0d9
RDX: 0000200000000040 RSI: 0000000040786e88 RDI: 0000000000000004
RBP: 00007f46ed035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f46ed226038 R14: 00007f46ed225fa0 R15: 00007ffe6572b548
 </TASK>
