INFO: task syz.7.3622:22075 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.3622      state:D stack:25128 pid:22075 tgid:22074 ppid:11690  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: 0033:0x7fe183b8ebe9
RSP: 002b:00007fe184a19038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fe183dc5fa0 RCX: 00007fe183b8ebe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fe183dc5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe183dc6038 R14: 00007fe183dc5fa0 R15: 00007ffc95975f98
 </TASK>
INFO: task syz.7.3622:22084 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.3622      state:D stack:28936 pid:22084 tgid:22074 ppid:11690  task_flags:0x400040 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: 0033:0x7fe183b8ebe9
RSP: 002b:00007fe1849f8038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fe183dc6090 RCX: 00007fe183b8ebe9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fe183dc6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe183dc6128 R14: 00007fe183dc6090 R15: 00007ffc95975f98
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/34:
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by getty/5677:
 #0: ffff8881073370a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900029032f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400
4 locks held by udevd/5842:
 #0: ffff88810a8e10a0 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xb7/0xe10
 #1: ffff888023301c88 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x55/0x3c0
 #2: ffff8880309dc968 (kn->active#31){++++}-{0:0}, at: kernfs_seq_start+0x75/0x3c0
 #3: ffff88811225e198 (&dev->mutex){....}-{4:4}, at: manufacturer_show+0x26/0xa0
1 lock held by udevd/6251:
 #0: ffff88802139a358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
6 locks held by kworker/0:7/7182:
 #0: ffff88801bb20548 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90002d9fbc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
 #2: ffff8880228d6198 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4a20
 #3: ffff88811225e198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400
 #4: ffff88811225c160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x400
 #5: ffffffff8dfe0350 (umhelper_sem){++++}-{4:4}, at: usermodehelper_read_trylock+0xf0/0x2b0
3 locks held by kworker/u8:3/16556:
 #0: ffff88804b039f98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140
 #1: ffff88804b024008 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880
 #2: ffff88802ab59f18 (key#18){+...}-{3:3}, at: batadv_nc_process_nc_paths+0xba/0x3a0
1 lock held by syz.7.3622/22075:
 #0: ffff88802139a358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340
1 lock held by syz.7.3622/22084:
 #0: ffff88802139a358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340
1 lock held by syz.5.3758/22605:
 #0: ffff88802139a358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340
1 lock held by syz.5.3758/22628:
 #0: ffff88802139a358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340

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

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+0x3fc/0x770
 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: 0 Comm: swapper/0 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:pv_native_safe_halt+0x13/0x20
Code: 53 e7 02 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d 73 67 0e 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff8de07d80 EFLAGS: 00000282
RAX: cb72974f1e70da00 RBX: ffffffff819683c8 RCX: cb72974f1e70da00
RDX: 0000000000000001 RSI: ffffffff8d9b8241 RDI: ffffffff8be33880
RBP: ffffffff8de07eb8 R08: ffff88804b032f9b R09: 1ffff110096065f3
R10: dffffc0000000000 R11: ffffed10096065f4 R12: ffffffff8fa39030
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1bd2a20
FS:  0000000000000000(0000) GS:ffff8880b8618000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffef2463cd8 CR3: 000000010e948000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 default_idle+0x13/0x20
 default_idle_call+0x74/0xb0
 do_idle+0x1e8/0x510
 cpu_startup_entry+0x44/0x60
 rest_init+0x2de/0x300
 start_kernel+0x3a9/0x410
 x86_64_start_reservations+0x24/0x30
 x86_64_start_kernel+0x143/0x1c0
 common_startup_64+0x13e/0x147
 </TASK>
