INFO: task syz.3.293:7388 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.293       state:D stack:24712 pid:7388  tgid:7387  ppid:6080   task_flags:0x400140 flags:0x00004004
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/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd51958ec29
RSP: 002b:00007fd51a45c038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd5197d5fa0 RCX: 00007fd51958ec29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd5197d5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd5197d6038 R14: 00007fd5197d5fa0 R15: 00007ffea005aa08
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8dd3aca0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5655:
 #0: ffff88810a1fa0a0 (&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
1 lock held by udevd/5946:
 #0: ffff8881098c6358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
1 lock held by syz.3.293/7388:
 #0: ffff8881098c6358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340
2 locks held by syz.5.987/10368:
1 lock held by syz.5.987/10386:
2 locks held by syz.1.988/10378:
2 locks held by syz.7.989/10389:

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

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+0xf93/0xfe0
 kthread+0x711/0x8a0
 ret_from_fork+0x439/0x7d0
 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: 10369 Comm: syz.5.987 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:update_irq_load_avg+0x6a9/0xe50
Code: 88 06 00 00 41 8b 07 4c 0f af f0 49 c1 ee 20 45 29 f4 41 81 c4 7e b6 00 00 4c 8b 74 24 28 44 89 ed 81 e5 ff 03 00 00 41 01 ec <49> bf 00 00 00 00 00 fc ff df 42 0f b6 04 3a 84 c0 0f 85 4a 04 00
RSP: 0018:ffffc90006af74f0 EFLAGS: 00000093
RAX: 00000000000003e9 RBX: ffff888136639fc0 RCX: 0000000000000000
RDX: 1ffff11026cc758b RSI: 000000000004573d RDI: ffff88813663aaf8
RBP: 00000000000003ee R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000d5ee9c R12: 0000000000000005
R13: 00000000000003ee R14: ffff88813663ac5c R15: 1ffff11026cc7588
FS:  00007f769af666c0(0000) GS:ffff8881a417e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff4095bd28 CR3: 000000003a72a000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 update_rq_clock+0x284/0x5b0
 __schedule+0x473/0x4cc0
 schedule+0x165/0x360
 schedule_timeout+0x9a/0x270
 wait_for_completion+0x2bf/0x5d0
 rdmsr_safe_on_cpu+0x150/0x230
 msr_read+0x14d/0x250
 vfs_read+0x200/0xa30
 ksys_read+0x145/0x250
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f769a18ec29
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:00007f769af66038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f769a3d5fa0 RCX: 00007f769a18ec29
RDX: 0000000000018ff8 RSI: 0000200000019680 RDI: 0000000000000006
RBP: 00007f769a211e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f769a3d6038 R14: 00007f769a3d5fa0 R15: 00007ffe6383e568
 </TASK>
