INFO: task syz.4.834:9475 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.4.834       state:D stack:24456 pid:9475  tgid:9473  ppid:8404   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7bf/0x1550
 sync_bdevs+0x276/0x470
 __ia32_sys_sync+0xc5/0x120
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f19a759e0d9
RSP: 002b:00007f19a83ba028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f19a7825fa0 RCX: 00007f19a759e0d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f19a7825fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f19a7826038 R14: 00007f19a7825fa0 R15: 00007ffc06910108
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/u8:1/13:
 #0: ffff8881012d5940 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90000127c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffffffff90019328 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810
 #3: ffffffff90027ec0 (rtnl_mutex){+.+.}-{4:4}, at: ops_undo_list+0x28e/0x8d0
 #4: ffff8881012d4aa0 (&root->kernfs_supers_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x3f/0x140
5 locks held by kworker/u9:1/29:
1 lock held by khungtaskd/34:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by dhcpcd/5345:
 #0: ffff888112d956e8 (nlk_cb_mutex-ROUTE){+.+.}-{4:4}, at: __netlink_dump_start+0xf4/0x7b0
 #1: ffffffff90027ec0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dumpit+0x92/0x200
2 locks held by getty/5425:
 #0: ffff8881773b20a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900028602e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
1 lock held by sshd/5523:
1 lock held by udevd/5721:
 #0: ffff88816c11d350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
3 locks held by kworker/1:5/6212:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90007fd7c40 (netdev_work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffffffff90027ec0 (rtnl_mutex){+.+.}-{4:4}, at: netdev_work_proc+0x6f/0x770
3 locks held by kworker/1:6/6213:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90008defc40 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffffffff90027ec0 (rtnl_mutex){+.+.}-{4:4}, at: switchdev_deferred_process_work+0xe/0x20
1 lock held by syz.4.834/9475:
 #0: ffff88816c11d350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x276/0x470
1 lock held by syz.7.932/10184:
1 lock held by syz.7.941/10237:
3 locks held by kworker/1:7/10587:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90007c37c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff888178b42250 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x1fd/0x3b0
1 lock held by syz.7.1154/11431:
6 locks held by kworker/0:8/11680:
 #0: ffff8881056e6d40 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90008eb7c40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff88816f9191d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30
 #3: ffff88816f91e568 (&port_dev->status_lock){+.+.}-{4:4}, at: hub_event+0x20a1/0x4d30
 #4: ffff88816f8a9660 (hcd->address0_mutex){+.+.}-{4:4}, at: hub_event+0x20c9/0x4d30
 #5: ffffffff8f8d57c8 (ehci_cf_port_reset_rwsem){.+.+}-{4:4}, at: hub_port_reset+0x14d/0x1810
2 locks held by syz.0.1218/11843:
 #0: ffff8881a17aa0d8 (&type->s_umount_key#122/1){+.+.}-{4:4}, at: sget_fc+0x938/0x1900
 #1: ffff88816c11d350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
1 lock held by syz.1.1380/12640:
 #0: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770

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

NMI backtrace for cpu 1
CPU: 1 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>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 12640 Comm: syz.1.1380 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:__lock_acquire+0x437/0x2cf0
Code: b6 89 c5 00 00 00 84 c9 0f b6 d3 0f b6 c9 0f 44 ca 89 4c 24 10 45 8b a6 98 0b 00 00 41 8d 4c 24 ff 83 f9 ff 41 bd ff ff ff ff <44> 0f 4c e9 41 ff c5 41 8d 5c 24 01 49 ff cc 89 d9 83 c1 fe 78 40
RSP: 0018:ffffc90003c1f338 EFLAGS: 00000046
RAX: 0000000000020007 RBX: 0000000000000003 RCX: 00000000ffffffff
RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88817757e4e0 R08: ffffffff8177827f R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8eb59c60 R12: 0000000000000000
R13: 00000000ffffffff R14: ffff88817757d940 R15: ffff88817757e4e0
FS:  00007f41ab6776c0(0000) GS:ffff88818d955000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f5e5d58de0 CR3: 000000010ee92000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 lock_acquire+0x106/0x350
 unwind_next_frame+0xac/0x2550
 arch_stack_walk+0x11b/0x150
 stack_trace_save+0xa9/0x100
 save_stack+0x122/0x230
 __reset_page_owner+0x71/0x1f0
 free_pages_prepare+0x960/0xa60
 __free_contig_range_common+0x174/0x340
 free_pages_bulk+0x48/0x120
 vfree+0x224/0x4a0
 kcov_close+0x28/0x50
 __fput+0x418/0xa50
 task_work_run+0x1d9/0x270
 do_exit+0x73a/0x2360
 do_group_exit+0x22d/0x2f0
 get_signal+0x121b/0x12c0
 arch_do_signal_or_restart+0xbb/0x860
 exit_to_user_mode_loop+0x104/0x730
 do_syscall_64+0x353/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f41aa79e0d9
Code: Unable to access opcode bytes at 0x7f41aa79e0af.
RSP: 002b:00007f41ab6770e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f41aaa26098 RCX: 00007f41aa79e0d9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f41aaa26098
RBP: 00007f41aaa26090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f41aaa26128 R14: 00007fff21647940 R15: 00007fff21647a28
 </TASK>
