INFO: task syz.2.146:6132 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.146       state:D stack:24808 pid:6132  tgid:6131  ppid:5918   task_flags:0x400140 flags:0x00080003
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: 0033:0x7f2fa278f749
RSP: 002b:00007f2fa36b4038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f2fa29e5fa0 RCX: 00007f2fa278f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f2fa29e5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2fa29e6038 R14: 00007f2fa29e5fa0 R15: 00007ffc1872fc08
 </TASK>
INFO: task syz.1.171:6191 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.171       state:D stack:25992 pid:6191  tgid:6190  ppid:5913   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: 0033:0x7fa05b58f749
RSP: 002b:00007fa05c4c6038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fa05b7e5fa0 RCX: 00007fa05b58f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fa05b7e5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa05b7e6038 R14: 00007fa05b7e5fa0 R15: 00007ffef3aee408
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/1:0/24:
1 lock held by khungtaskd/35:
 #0: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
2 locks held by kworker/u10:8/1097:
 #0: ffff888102bac148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0
 #1: ffffc90007bcfba0 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0
1 lock held by udevd/5259:
2 locks held by getty/5640:
 #0: ffff88811442c0a0 (&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
1 lock held by udevd/5921:
 #0: ffff88810a4f6358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
1 lock held by udevd/6088:
 #0: ffff88810a52a358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
1 lock held by syz.2.146/6132:
 #0: ffff88810a4f6358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340
1 lock held by syz.1.171/6191:
 #0: ffff88810a4f6358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340
1 lock held by syz.3.789/7868:
 #0: ffff88810a52a358 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x1ac/0x340
1 lock held by syz.0.958/8347:
 #0: ffff88810a4f6358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30
1 lock held by syz.8.1409/9798:
 #0: ffff88810cd82420 (sb_writers#3){.+.+}-{0:0}, at: direct_splice_actor+0x49/0x160

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

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: 10018 Comm: syz.9.1486 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+0x3/0x120
Code: bf 8b 48 c7 c6 c0 0f bf 8b eb 1c 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 <41> 56 53 48 83 ec 10 65 48 8b 05 de 04 27 07 48 89 44 24 08 65 8b
RSP: 0018:ffffc90004097160 EFLAGS: 00000082
RAX: 0000000000000001 RBX: ffffffff81000130 RCX: ffff8881131a3a00
RDX: 0000000000000000 RSI: ffffffff8bbf0fc0 RDI: ffffffff8bbf0f80
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffc900040972b8 R11: ffffffff81ac4250 R12: 1ffff92000812e4d
R13: ffffc900040972a0 R14: ffffc90004097268 R15: ffffffff81739c45
FS:  00007ff8c559b6c0(0000) GS:ffff8882a9f36000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32c0cff8 CR3: 00000001a5dde000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 rcu_is_watching+0x15/0xb0
 unwind_next_frame+0xd4/0x2390
 arch_stack_walk+0x11c/0x150
 stack_trace_save+0x9c/0xe0
 save_trace+0x49/0x390
 mark_lock+0xf1/0x190
 __lock_acquire+0x9b6/0xd20
 lock_acquire+0x120/0x360
 __mutex_lock+0x187/0x1350
 usblp_open+0x54/0x420
 usb_open+0x156/0x1e0
 chrdev_open+0x4cc/0x5e0
 do_dentry_open+0x953/0x13f0
 vfs_open+0x3b/0x340
 path_openat+0x2ee5/0x3830
 do_filp_open+0x1fa/0x410
 do_sys_openat2+0x121/0x1c0
 __x64_sys_openat+0x138/0x170
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff8c478df90
Code: 48 89 44 24 20 75 93 44 89 54 24 0c e8 69 95 02 00 44 8b 54 24 0c 89 da 48 89 ee 41 89 c0 bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 38 44 89 c7 89 44 24 0c e8 bc 95 02 00 8b 44
RSP: 002b:00007ff8c559ab70 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007ff8c478df90
RDX: 0000000000000002 RSI: 00007ff8c559ac10 RDI: 00000000ffffff9c
RBP: 00007ff8c559ac10 R08: 0000000000000000 R09: 00007ff8c559a987
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000
R13: 00007ff8c49e6038 R14: 00007ff8c49e5fa0 R15: 00007ffc1ab302e8
 </TASK>
