INFO: task syz.0.884:8009 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0
task:syz.0.884       state:D stack:27744 pid:8009  tgid:8008  ppid:6350   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17d4/0x5820
 schedule+0x164/0x2b0
 schedule_preempt_disabled+0x13/0x30
 __mutex_lock+0x7c1/0x1550
 sync_bdevs+0x276/0x470
 __ia32_sys_sync+0xc5/0x120
 do_syscall_64+0x166/0x520
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5e8639e159
RSP: 002b:00007f5e871d6028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f5e86625fa0 RCX: 00007f5e8639e159
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f5e86625fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5e86626038 R14: 00007f5e86625fa0 R15: 00007ffcfaff4f28
 </TASK>

Showing all locks held in the system:
locks held by khungtaskd/34: 1, last CPU#0:
 #0: ffffffff8ed5c6a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
locks held by udevd/5061: 1, last CPU#1:
 #0: ffffffff8f4ec0b8 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_path_perm+0x251/0x560
locks held by getty/5441: 2, on CPU#0:
 #0: ffff8881149ba0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc900034762e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360
locks held by udevd/5726: 1, on CPU#1:
 #0: ffff88816d04f350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70
locks held by kworker/0:5/5779: 4, last CPU#0:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #1: ffffc90006abfc40 (drain_vmap_work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630
 #2: ffffffff8ee8b020 (vmap_purge_lock){+.+.}-{4:4}, at: drain_vmap_area_work+0x17/0x40
 #3: ffffffff8ed5c6a0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550
locks held by syz.0.884/8009: 1, on CPU#1:
 #0: ffff88816d04f350 (&disk->open_mutex){+.+.}-{4:4}, at: sync_bdevs+0x276/0x470
locks held by syz-executor/10673: 4, last CPU#1:
 #0: ffffffff8ee35b50 (dup_mmap_sem){++++}-{0:0}, at: copy_mm+0x10f/0x480
 #1: ffff8881bf24d038 (&mm->mmap_lock){++++}-{4:4}, at: dup_mmap+0x195/0x1dc0
 #2: ffff88816c7ac378 (&mm->mmap_lock/1){+.+.}-{4:4}, at: dup_mmap+0x221/0x1dc0
 #3: ffffffff8ed5c6a0 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x240
locks held by syz-executor/12107: 4, last CPU#1:
 #0: ffffffff8ee35b50 (dup_mmap_sem){++++}-{0:0}, at: copy_mm+0x10f/0x480
 #1: ffff8881baa81078 (&mm->mmap_lock){++++}-{4:4}, at: dup_mmap+0x195/0x1dc0
 #2: ffff88816c7ae9b8 (&mm->mmap_lock/1){+.+.}-{4:4}, at: dup_mmap+0x221/0x1dc0
 #3: ffffffff8ed5c6a0 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x240
locks held by syz-executor/13048: 4, last CPU#1:
 #0: ffff888029560460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90
 #1: ffff888119ae38d0 (&type->i_mutex_dir_key#5/1){+.+.}-{4:4}, at: filename_create+0x200/0x370
 #2: ffffffff8f4ec0b8 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_path_perm+0x251/0x560
 #3: ffffffff8ed5c6a0 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 34 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
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+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17d/0x390
 sys_info+0x135/0x170
 watchdog+0xfd7/0x1030
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 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: 16 Comm: pr/ttyS0 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:io_serial_out+0x7c/0xc0
Code: 52 57 fc 44 89 f9 d3 e5 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 4c 05 c7 fc 41 03 2e 89 d8 89 ea ee <5b> 41 5c 41 5e 41 5f 5d c3 cc cc cc cc cc 44 89 f9 80 e1 07 38 c1
RSP: 0018:ffffc90000157900 EFLAGS: 00000002
RAX: 0000000000000020 RBX: 0000000000000020 RCX: 0000000000000000
RDX: 00000000000003f8 RSI: 0000000000000000 RDI: 0000000000000020
RBP: 00000000000003f8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff85705b30 R12: dffffc0000000000
R13: 0000000000000020 R14: ffffffff9ad27100 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88818d6e4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffbf0f5da08 CR3: 0000000169eac000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 __serial8250_console_fifo_write+0x1e6/0x3e0
 serial8250_console_write+0xaa1/0x1200
 nbcon_emit_next_record+0xef5/0x1a90
 nbcon_kthread_func+0x679/0x880
 kthread+0x38b/0x480
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
