INFO: task kworker/u9:4:4448 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u9:4    state:D stack:22208 pid:4448  tgid:4448  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: writeback wb_workfn (flush-7:6)
Call Trace:
 <TASK>
 __schedule+0x15dd/0x52d0
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7fe/0x1300
 jfs_commit_inode+0x1ca/0x530
 jfs_write_inode+0x145/0x220
 __writeback_single_inode+0x75a/0x11a0
 writeback_sb_inodes+0x992/0x1a20
 __writeback_inodes_wb+0x111/0x240
 wb_writeback+0x46a/0xb70
 wb_workfn+0xb4c/0xf50
 process_scheduled_works+0xb6e/0x18c0
 worker_thread+0xa53/0xfc0
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Showing all locks held in the system:
1 lock held by ksoftirqd/1/23:
1 lock held by khungtaskd/34:
 #0: ffffffff8e75e520 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
4 locks held by kworker/u9:4/4448:
 #0: ffff888162a96148 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0
 #1: ffffc90003447c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0
 #2: ffff88811fc020e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0
 #3: ffff8881164b9d40 (&jfs_ip->commit_mutex){+.+.}-{4:4}, at: jfs_commit_inode+0x1ca/0x530
2 locks held by getty/5636:
 #0: ffff8881775250a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000356b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0
3 locks held by kworker/0:3/5846:
 #0: ffff88810006b148 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0
 #1: ffffc900065d7c40 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0
 #2: ffff88817985b240 (&data->fib_lock){+.+.}-{4:4}, at: nsim_fib_event_work+0x202/0x3d0
4 locks held by syz.6.273/7329:
2 locks held by syz.6.848/10860:
 #0: ffff88811fc020e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
 #1: ffff888102be0820 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x1c2/0xbd0
2 locks held by syz.6.848/10861:
 #0: ffff88811fc020e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
 #1: ffff888102be0820 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x1c2/0xbd0
2 locks held by syz.6.848/10864:
 #0: ffff88811fc020e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
 #1: ffff888102be0820 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x1c2/0xbd0
2 locks held by syz.6.848/10867:
 #0: ffff88811fc020e0 (&type->s_umount_key#84){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
 #1: ffff888102be0820 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x1c2/0xbd0
2 locks held by syz.0.994/11518:
1 lock held by syz.7.995/11527:
2 locks held by syz.9.980/11534:
4 locks held by dhcpcd-run-hook/11574:

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

NMI backtrace for cpu 0
CPU: 0 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+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 sys_info+0x135/0x170
 watchdog+0xfd9/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x51e/0xb90
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 11527 Comm: syz.7.995 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: 0033:0x7fcbc3e53b0e
Code: c1 49 39 4f 08 72 54 8d 4d ff 85 ed 74 3b 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 39 f0 72 1b 4d 8b 07 49 89 c1 49 29 f1 <47> 0f b6 0c 08 45 84 c9 74 08 45 88 0c 00 49 8b 47 10 48 83 c0 01
RSP: 002b:00007fcbc4e67470 EFLAGS: 00000202
RAX: 00000000009eae59 RBX: 00007fcbc4e67530 RCX: 000000000000001a
RDX: 0000000000000001 RSI: 0000000000000001 RDI: 00007fcbc4e675d0
RBP: 0000000000000102 R08: 00007fcbb9c00000 R09: 00000000009eae58
R10: 0000000000000000 R11: 00007fcbc4e67540 R12: 0000000000000001
R13: 00007fcbc4052620 R14: 0000000000000000 R15: 00007fcbc4e675d0
FS:  00007fcbc4e686c0 GS:  0000000000000000
