INFO: task syz.1.811:8007 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.811       state:D stack:25128 pid:8007  tgid:8004  ppid:5845   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: 0033:0x7fa3b378ec29
RSP: 002b:00007fa3b4580038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fa3b39d5fa0 RCX: 00007fa3b378ec29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fa3b39d5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa3b39d6038 R14: 00007fa3b39d5fa0 R15: 00007ffe8039f258
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e33d320 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5672:
 #0: ffff8880269480a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900025e82f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
2 locks held by syz-executor/5849:
 #0: ffff888023cb40e0 (&type->s_umount_key#89){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0
 #1: ffffffff8e342c80 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x570
5 locks held by kworker/1:5/5907:
1 lock held by udevd/6484:
 #0: ffff8880223bb358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
1 lock held by syz.1.811/8007:
 #0: ffff8880223bb358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340

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

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+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: 7062 Comm: udevd 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:check_preemption_disabled+0x40/0x120
Code: 08 65 8b 05 e6 84 42 07 65 8b 0d db 84 42 07 f7 c1 ff ff ff 7f 74 23 65 48 8b 0d bb 84 42 07 48 3b 4c 24 08 0f 85 cc 00 00 00 <48> 83 c4 10 5b 41 5e 41 5f 5d c3 cc cc cc cc cc 48 c7 04 24 00 00
RSP: 0018:ffffc90006eb7e60 EFLAGS: 00000046
RAX: 0000000000000001 RBX: 0000000000000001 RCX: a4bee40a060fe500
RDX: 0000000000000000 RSI: ffffffff8c03da40 RDI: ffffffff8c03da00
RBP: ffffc90006eb7f38 R08: ffffffff8fc35777 R09: 1ffffffff1f86aee
R10: dffffc0000000000 R11: fffffbfff1f86aef R12: 0000000000000000
R13: 0000000000000052 R14: ffffc90006eb7f48 R15: ffff888108143a00
FS:  00007f3a62d3cc80(0000) GS:ffff8881a39fc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555636a9608 CR3: 000000010c564000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 rcu_is_watching+0x15/0xb0
 trace_irq_disable+0x37/0x110
 local_irq_disable_exit_to_user+0x1d/0x30
 do_syscall_64+0x139/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3a6289a93b
Code: 48 8b 15 f0 64 15 00 83 c8 ff 64 83 3a 15 75 0e 48 8b 7c 24 08 e8 d5 d4 07 00 f7 d8 19 c0 48 83 c4 18 c3 b8 52 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 10 48 8b 15 be 64 15 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffc1117edf8 EFLAGS: 00000206 ORIG_RAX: 0000000000000052
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 00007f3a6289a93b
RDX: 000055e7cde60b8f RSI: 00007ffc1117ee18 RDI: 00007ffc1117f218
RBP: 000055e293cde780 R08: 0000000000000006 R09: 19fc3a96e7caaa32
R10: 000000000000010f R11: 0000000000000206 R12: 000055e293cef900
R13: 00007ffc1117ee18 R14: 00007ffc1117f218 R15: 000055e2623e6ec8
 </TASK>
