INFO: task syz.9.3635:22818 blocked for more than 143 seconds.
      Tainted: G             L      syzkalle
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.9.3635      state:D stack:26992 pid:22818 tgid:22817 ppid:21303  task_flags:0x400140 flags:0x00080006
Call Trace:
 <TASK>
 __schedule+0x17db/0x58f0
 schedule+0x164/0x2b0
 cgroup_lock_and_drain_offline+0x51a/0x650
 cgroup1_get_tree+0x9d/0x890
 vfs_get_tree+0x92/0x2a0
 vfs_cmd_create+0xa2/0x200
 __se_sys_fsconfig+0x6b9/0x810
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f19c259e159
RSP: 002b:00007f19c07f6028 EFLAGS: 00000246 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 00007f19c2825fa0 RCX: 00007f19c259e159
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 000000000000000c
RBP: 00007f19c2635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f19c2826038 R14: 00007f19c2825fa0 R15: 00007ffff77618f8
 </TASK>

Showing all locks held in the system:
locks held by kworker/0:0/9: 4, on CPU#0:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900000e7c40 ((work_completion)(&helper->damage_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffc900000e7770 (crtc_ww_class_acquire){+.+.}-{0:0}, at: drm_atomic_helper_dirtyfb+0x106/0xfd0
 #3: ffffc900000e7798 (crtc_ww_class_mutex){+.+.}-{4:4}, at: drm_atomic_helper_dirtyfb+0x106/0xfd0
locks held by pr/ttyS0/16: 2, last CPU#1:
 #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/34: 1, last CPU#0:
 #0: ffffffff8ed5cbe0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by getty/5421: 2, on CPU#1:
 #0: ffff88817b4120a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000346e2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
locks held by kworker/u9:10/8656: 2, on CPU#0:
 #0: ffff8881697c2940 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc900040c7c40 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
locks held by kworker/u9:26/21588: 3, last CPU#0:
 #0: ffff88810f5ec140 ((wq_completion)btrfs-worker){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc9000485fc40 ((work_completion)(&work->normal_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff8ed5cbe0 (rcu_read_lock){....}-{1:3}, at: blk_mq_submit_bio+0x1c8d/0x2a70
locks held by syz.9.3635/22818: 1, on CPU#1:
 #0: ffff888170264468 (&fc->uapi_mutex){+.+.}-{4:4}, at: __se_sys_fsconfig+0x68d/0x810
locks held by syz-executor/25759: 2, on CPU#0:
 #0: ffff8881201ae0e8 (&type->s_umount_key#90){++++}-{4:4}, at: deactivate_super+0xac/0xe0
 #1: ffff8881201ae978 (&s->s_sync_lock){+.+.}-{4:4}, at: sync_inodes_sb+0x2cc/0xbf0
locks held by syz.6.4259/26637: 3, last CPU#1:
 #0: ffff8881012fa460 (sb_writers#5){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0
 #1: ffff8881a9759ae8 (&sb->s_type->i_mutex_key#15){++++}-{4:4}, at: shmem_file_write_iter+0x7f/0x120
 #2: ffffffff8ed5cbe0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550
locks held by udevadm/26662: 1, last CPU#0:
 #0: ffff8881012d4180 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_dop_revalidate+0x9e/0x650

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

NMI backtrace for cpu 0
CPU: 0 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 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: 47 54 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 1c 84 c4 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: 0000000000000032 RBX: 0000000000000032 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000000003f8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff857371f0 R12: dffffc0000000000
R13: 0000000000000032 R14: ffffffff9ad3f0c0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8882a8ccc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2ed06ff8 CR3: 0000000176b3c000 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>
