INFO: task syz.4.1498:10687 blocked for more than 142 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.1498      state:D stack:23656 pid:10687 tgid:10686 ppid:9530   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_timeout+0xc0/0x2c0
 __down_common+0x3b7/0x850
 down+0x80/0xd0
 console_lock+0x58/0x90
 con_font_op+0x46e/0xfe0
 vt_ioctl+0x1b93/0x20d0
 tty_ioctl+0x920/0xdd0
 __se_sys_ioctl+0xfc/0x170
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5d3c39e0d9
RSP: 002b:00007f5d3d278028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5d3c625fa0 RCX: 00007f5d3c39e0d9
RDX: 0000200000000000 RSI: 0000000000004b72 RDI: 000000000000000c
RBP: 00007f5d3c435024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5d3c626038 R14: 00007f5d3c625fa0 R15: 00007fffdfe2a728
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8eb59c20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5429:
 #0: ffff88810fd930a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034732e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
3 locks held by kworker/0:5/5669:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc900065dfc40 ((work_completion)(&helper->damage_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff88816a13e270 (&helper->lock){+.+.}-{4:4}, at: drm_fb_helper_damage_work+0x15b/0xf20
3 locks held by kworker/u9:11/6077:
1 lock held by udevd/6971:
2 locks held by kworker/0:9/8495:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90003dbfc40 (console_work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
10 locks held by syz.5.1430/10521:
1 lock held by syz.2.2081/12818:
2 locks held by syz.9.2083/12832:
1 lock held by cmp/12830:

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

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+0x17a/0x380
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
