INFO: task kworker/u9:0:26 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u9:0    state:D stack:20736 pid:26    tgid:26    ppid:2      task_flags:0x4208060 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:2)
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_write_slowpath+0x872/0xfe0
 down_write+0x1ab/0x1f0
 f2fs_issue_checkpoint+0x39c/0x570
 f2fs_balance_fs_bg+0x54d/0x980
 f2fs_write_node_pages+0x146/0x6e0
 do_writepages+0x32e/0x550
 __writeback_single_inode+0x145/0xff0
 writeback_sb_inodes+0x6c7/0x1010
 __writeback_inodes_wb+0x111/0x240
 wb_writeback+0x44f/0xaf0
 wb_workfn+0xaef/0xef0
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u9:0/26:
 #0: ffff88801b38f148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc900001efbc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff8881178ea0e0 (&type->s_umount_key#59){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0
 #3: ffff888118fa5410 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_issue_checkpoint+0x39c/0x570
1 lock held by khungtaskd/34:
 #0: ffffffff8e13a0e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by udevd/5297:
2 locks held by getty/5675:
 #0: ffff88810a6d90a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900029062f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
4 locks held by syz.2.6/5929:
1 lock held by udevd/7199:
 #0: ffffffff8e6e49e8 (uuid_mutex){+.+.}-{4:4}, at: btrfs_control_ioctl+0x111/0x360
2 locks held by syz-executor/10037:
 #0: ffffffff8e88f188 (bio_slab_lock){+.+.}-{4:4}, at: bioset_exit+0x44a/0x690
 #1: ffffffff8e13fa40 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x570
2 locks held by syz.8.618/10349:
 #0: ffff888037ca60e0 (&type->s_umount_key#57/1){+.+.}-{4:4}, at: alloc_super+0x204/0x970
 #1: ffffffff8dfe1868 (wq_pool_mutex){+.+.}-{4:4}, at: __alloc_workqueue+0x9eb/0x1b70
2 locks held by udevadm/10354:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 34 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+0x189/0x250
 nmi_cpu_backtrace+0x39e/0x3d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 watchdog+0xf93/0xfe0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 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: 5929 Comm: syz.2.6 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:preempt_count_add+0xc7/0x1a0
Code: 00 65 4c 8b 34 25 08 e0 a0 92 49 81 c6 e0 14 00 00 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 3c 2f 93 00 49 89 1e <5b> 41 5e 41 5f c3 cc cc cc cc cc 89 fb 90 e8 d6 2a 35 03 85 c0 74
RSP: 0018:ffffc90004d7ec80 EFLAGS: 00000002
RAX: 0000000000000002 RBX: 0000000000000000 RCX: ffffffff99ac3303
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffffc90004d7eef0 R08: ffffffff8fa3a737 R09: 1ffffffff1f474e6
R10: dffffc0000000000 R11: fffffbfff1f474e7 R12: dffffc0000000000
R13: 0000000000000001 R14: ffff88804b039f80 R15: dffffc0000000000
FS:  00007f2b1bdd26c0(0000) GS:ffff8880b8612000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557d60333668 CR3: 0000000117598000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 raw_spin_rq_lock_nested+0x1e/0x140
 __schedule+0x36b/0x4cc0
 preempt_schedule_irq+0xb5/0x150
 irqentry_exit+0x6f/0x90
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:lock_acquire+0x175/0x360
Code: 00 00 00 00 9c 8f 44 24 30 f7 44 24 30 00 02 00 00 0f 85 cd 00 00 00 f7 44 24 08 00 02 00 00 74 01 fb 65 48 8b 05 7b 81 03 11 <48> 3b 44 24 58 0f 85 f2 00 00 00 48 83 c4 60 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc90004d7f060 EFLAGS: 00000206
RAX: a2459d8161f82100 RBX: 0000000000000000 RCX: a2459d8161f82100
RDX: 0000000000000000 RSI: ffffffff8dba996e RDI: ffffffff8be33f80
RBP: ffffffff840a317c R08: 0000000000000000 R09: ffffffff840a317c
R10: dffffc0000000000 R11: ffffed10057e6041 R12: 0000000000000000
R13: ffff888118fa43b0 R14: 0000000000000001 R15: 0000000000000246
 down_write+0x96/0x1f0
 f2fs_write_checkpoint+0x51c/0x1df0
 f2fs_issue_checkpoint+0x3ac/0x570
 f2fs_do_sync_file+0x869/0x1860
 f2fs_file_write_iter+0x753/0x2410
 do_iter_readv_writev+0x61c/0x8b0
 vfs_writev+0x31a/0x960
 __x64_sys_pwritev+0x197/0x2a0
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2b1af8ec29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2b1bdd2038 EFLAGS: 00000246 ORIG_RAX: 0000000000000128
RAX: ffffffffffffffda RBX: 00007f2b1b1d5fa0 RCX: 00007f2b1af8ec29
RDX: 0000000000000001 RSI: 0000200000000540 RDI: 000000000000000a
RBP: 00007f2b1b011e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2b1b1d6038 R14: 00007f2b1b1d5fa0 R15: 00007ffd07c7edb8
 </TASK>
