INFO: task syz.8.9592:31520 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.8.9592      state:D stack:26024 pid:31520 tgid:31519 ppid:14151  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x1798/0x4cc0
 schedule+0x165/0x360
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7e6/0x1350
 sync_bdevs+0x1ac/0x340
 ksys_sync+0xb9/0x150
 __ia32_sys_sync+0xe/0x20
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f171b78efc9
RSP: 002b:00007f171c598038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f171b9e5fa0 RCX: 00007f171b78efc9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f171b9e5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f171b9e6038 R14: 00007f171b9e5fa0 R15: 00007ffcc999ca98
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/35:
 #0: ffffffff8df3d2e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5638:
 #0: ffff8881773660a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000357b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
2 locks held by kworker/u9:28/26756:
 #0: ffff888100089148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90009377ba0 ((work_completion)(&(&kfence_timer)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
1 lock held by udevd/29634:
 #0: ffff888109546358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
1 lock held by udevd/29756:
 #0: ffff8881095d2358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
1 lock held by syz.8.9592/31520:
 #0: ffff8881095d2358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340
1 lock held by syz.6.10313/1460:

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

NMI backtrace for cpu 0
CPU: 0 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+0x189/0x250
 nmi_cpu_backtrace+0x39e/0x3d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 watchdog+0xf60/0xfa0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 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: 1460 Comm: syz.6.10313 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:do_raw_spin_lock+0x8/0x290
Code: 03 38 c1 7c 90 48 89 df e8 75 e0 87 00 eb 86 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 48 89 e5 <41> 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec 80 00 00 00 48 89
RSP: 0018:ffffc9000762f8f0 EFLAGS: 00000096
RAX: bc3a91f55e0bbb00 RBX: ffff88810a5ec380 RCX: bc3a91f55e0bbb00
RDX: 0000000000000000 RSI: ffffffff8d8f58f5 RDI: ffff88810a5ec380
RBP: ffffc9000762f8f0 R08: 0000000000000000 R09: ffffffff812b247f
R10: dffffc0000000000 R11: fffffbfff1efa02f R12: dffffc0000000000
R13: ffffc9000762fa00 R14: 1ffff92000ec5f20 R15: dffffc0000000000
FS:  00007f30586926c0(0000) GS:ffff8882a9f35000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f42792dcfb8 CR3: 000000019eb96000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 _raw_spin_lock_irq+0xae/0xf0
 io_flush_timeouts+0xbf/0x400
 __io_commit_cqring_flush+0x133/0x190
 __io_submit_flush_completions+0xe92/0xfc0
 io_handle_tw_list+0x44e/0x4c0
 tctx_task_work_run+0x99/0x370
 tctx_task_work+0x3f/0x90
 task_work_run+0x1d4/0x260
 get_signal+0x11ec/0x1340
 arch_do_signal_or_restart+0xa0/0x790
 irqentry_exit_to_user_mode+0x7e/0x110
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0033:0x7f305764e253
Code: f5 13 00 48 81 c4 90 00 00 00 48 98 5b c3 66 0f 1f 84 00 00 00 00 00 41 54 55 53 48 89 fb 48 81 ec d0 00 00 00 48 89 74 24 28 <48> 89 54 24 30 48 89 4c 24 38 4c 89 44 24 40 4c 89 4c 24 48 84 c0
RSP: 002b:00007f3058691f70 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 00007f3057813313 RCX: 00007f3057816c54
RDX: 000000000001e409 RSI: 0000000000000000 RDI: 00007f3057813313
RBP: 00007f3057816c54 R08: 0000000000000002 R09: 3fffffffffffffff
R10: 4000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f30579e6038 R14: 00007f30579e5fa0 R15: 00007fff47cbed28
 </TASK>
