INFO: task syz.3.5134:24105 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.3.5134      state:D stack:25072 pid:24105 tgid:24104 ppid:21061  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: 0033:0x7f6d1899e0d9
RSP: 002b:00007f6d198ce028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f6d18c25fa0 RCX: 00007f6d1899e0d9
RDX: 00002000000000c0 RSI: 0000200000000000 RDI: 0000000000000000
RBP: 00007f6d18a35024 R08: 00002000000001c0 R09: 0000000000000000
R10: 0000000000010012 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6d18c26038 R14: 00007f6d18c25fa0 R15: 00007ffcae3adc18
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/35:
 #0: ffffffff8eb59ca0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5428:
 #0: ffff8881123030a0 (&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
5 locks held by kworker/u8:4/20708:
 #0: ffff8881012d5940 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90009007c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffffffff90019368 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810
 #3: ffff88816a9fd610 (&wg->device_update_lock){+.+.}-{4:4}, at: wg_destruct+0x116/0x310
 #4: ffffffff8eb5ffa8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
4 locks held by kworker/0:3/22211:
5 locks held by kworker/0:4/22213:
 #0: ffff8881052fe140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc900075b7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff888108a831d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30
 #3: ffff88802a1a91d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0xfc/0x9a0
 #4: ffff88802303e1a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb9/0x880
5 locks held by kworker/0:5/22214:
 #0: ffff8881052fe140 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90007597c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff8881077cb1d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30
 #3: ffff88811c36e1d8 (&dev->mutex){....}-{4:4}, at: usb_disconnect+0xfc/0x9a0
 #4: ffff88811c36d1a0 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb9/0x880
6 locks held by syz.9.5401/25228:
 #0: ffff888103744260 (&dev->clientlist_mutex){+.+.}-{4:4}, at: drm_client_dev_restore+0xb1/0x290
 #1: ffff88816bc10270 (&helper->lock){+.+.}-{4:4}, at: __drm_fb_helper_restore_fbdev_mode_unlocked+0x7b/0x1c0
 #2: ffff888103744128 (&dev->master_mutex){+.+.}-{4:4}, at: drm_master_internal_acquire+0x20/0x80
 #3: ffff88816bc10090 (&client->modeset_mutex){+.+.}-{4:4}, at: drm_client_modeset_commit_locked+0x4c/0x4d0
 #4: ffffc90006fe7730 (crtc_ww_class_acquire){+.+.}-{0:0}, at: drm_client_modeset_commit_atomic+0x11a/0x7e0
 #5: ffffc90006fe7758 (crtc_ww_class_mutex){+.+.}-{4:4}, at: drm_client_modeset_commit_atomic+0x11a/0x7e0
1 lock held by cxacru/25233:
 #0: ffffffff8e9f59c8 (umhelper_sem){++++}-{4:4}, at: usermodehelper_read_trylock+0xfc/0x2c0
1 lock held by dhcpcd-run-hook/25810:

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

NMI backtrace for cpu 0
CPU: 0 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>
