INFO: task kworker/u9:2:51 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u9:2    state:D stack:22728 pid:51    tgid:51    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: writeback wb_workfn (flush-7:9)
Call Trace:
 <TASK>
 __schedule+0x17d9/0x56c0
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_write_slowpath+0x87d/0x1080
 down_write+0x1bc/0x200
 f2fs_down_write_trace+0x34/0x1f0
 f2fs_issue_checkpoint+0x414/0x6f0
 f2fs_balance_fs_bg+0x573/0x990
 f2fs_write_node_pages+0x158/0x700
 do_writepages+0x338/0x560
 __writeback_single_inode+0x12e/0xf90
 writeback_sb_inodes+0x9de/0x1b00
 __writeback_inodes_wb+0x114/0x240
 wb_writeback+0x42f/0xad0
 wb_workfn+0xc92/0x10f0
 process_scheduled_works+0xa8e/0x14e0
 worker_thread+0xa47/0xfb0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/35:
 #0: ffffffff8e959c20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
4 locks held by kworker/u9:2/51:
 #0: ffff888162697940 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90000bb7c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff88816a9880d8 (&type->s_umount_key#55){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0
 #3: ffff8881be5454b8 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write_trace+0x34/0x1f0
2 locks held by kworker/1:3/997:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc90006d27c40 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
2 locks held by dhcpcd/5356:
 #0: ffff8880127436e8 (nlk_cb_mutex-ROUTE){+.+.}-{4:4}, at: __netlink_dump_start+0xf4/0x7b0
 #1: ffffffff8fded200 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dump_ifinfo+0xa74/0x14a0
2 locks held by getty/5441:
 #0: ffff88816b2c50a0 (&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
6 locks held by kworker/u8:2/5656:
 #0: ffff8881012bd940 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc900047bfc40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffffffff8fdde668 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810
 #3: ffffffff8fded200 (rtnl_mutex){+.+.}-{4:4}, at: ieee80211_unregister_hw+0x55/0x2c0
 #4: ffff88816bb907a0 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: cfg80211_leave+0x178/0x200
 #5: ffffffff8e95ff28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
3 locks held by kworker/0:5/5677:
3 locks held by syz.9.446/8466:
1 lock held by syz-executor/11478:
 #0: ffff88816c04a0d8 (&type->s_umount_key#82){++++}-{4:4}, at: deactivate_super+0xa9/0xe0
2 locks held by syz-executor/12742:
 #0: ffffffff8f55a068 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250
 #1: ffffffff8fded200 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8a3/0x1bd0
1 lock held by syz.0.1072/12794:
1 lock held by syz.8.1074/12802:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 35 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
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: 8466 Comm: syz.9.446 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:__lock_acquire+0x468/0x2cf0
Code: 41 8d 5c 24 01 49 ff cc 89 d9 83 c1 fe 78 40 45 89 e7 41 81 e7 ff ff ff 7f 83 f9 31 73 1d 4b 8d 0c bf 41 8b 8c ce c0 0b 00 00 <31> c1 ff cb 49 ff cc f7 c1 00 60 00 00 74 cf eb 17 48 c7 c7 50 7f
RSP: 0018:ffffc90004dceae8 EFLAGS: 00000097
RAX: 0000000000040262 RBX: 0000000000000002 RCX: 00000000000508b4
RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88817213e558 R08: ffffffff82564944 R09: 0000000000000000
R10: 0000000000000000 R11: ffff888169cfc0d8 R12: 0000000000000000
R13: 0000000000000000 R14: ffff88817213d940 R15: 0000000000000000
FS:  00007f8bf7dd36c0(0000) GS:ffff88818dc1d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e03a94a3a0 CR3: 0000000166726000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 lock_acquire+0x106/0x350
 _raw_spin_lock+0x2e/0x40
 locked_inode_to_wb_and_lock_list+0x204/0x310
 writeback_single_inode+0x509/0xe70
 sync_inode_metadata+0x122/0x1d0
 f2fs_write_checkpoint+0xbf1/0x2710
 f2fs_issue_checkpoint+0x424/0x6f0
 f2fs_do_sync_file+0xcd3/0x1960
 f2fs_file_write_iter+0x723/0x28e0
 do_iter_readv_writev+0x612/0x8c0
 vfs_writev+0x343/0x990
 __se_sys_pwritev2+0x177/0x2a0
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8bf6f9ce59
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:00007f8bf7dd3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007f8bf7215fa0 RCX: 00007f8bf6f9ce59
RDX: 0000000000000001 RSI: 0000200000000100 RDI: 0000000000000008
RBP: 00007f8bf7032e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000005405 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8bf7216038 R14: 00007f8bf7215fa0 R15: 00007fffcda28a88
 </TASK>
