b_state=0x0000012d, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x0000012d, b_size=512
device loop0 blocksize: 4096
INFO: task syz-executor0:7208 blocked for more than 140 seconds.
      Not tainted 4.9.113-g47bbcd6 #10
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D29432  7208   3849 0x00000004
 ffff8801cdebc800 ffff8801cfd1d500 ffff8801d30f9a40 ffff8801d0841800
 ffff8801db221c18 ffff8801a44e7728 ffffffff839e909d ffffffff81235647
 0000000000000000 ffff8801cdebd0c0 0000000600000007 ffff8801db2224e8
Call Trace:
 [<ffffffff839ea69f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839f5cd8>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f5cd8>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee7587>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839f3aac>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839f3aac>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff8156a838>] inode_lock include/linux/fs.h:766 [inline]
 [<ffffffff8156a838>] do_truncate2+0x128/0x1f0 fs/open.c:61
 [<ffffffff815a643e>] handle_truncate fs/namei.c:2990 [inline]
 [<ffffffff815a643e>] do_last fs/namei.c:3419 [inline]
 [<ffffffff815a643e>] path_openat+0x251e/0x3590 fs/namei.c:3534
 [<ffffffff815ab777>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8156df4d>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff8156e2a7>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff8156e2a7>] SyS_open fs/open.c:1085 [inline]
 [<ffffffff8156e2a7>] SYSC_creat fs/open.c:1110 [inline]
 [<ffffffff8156e2a7>] SyS_creat+0x27/0x30 fs/open.c:1108
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9f93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136675c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136675c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425de7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3682:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d81ec>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3778:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f8142>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211ee22>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor0/7208:
 #0:  (sb_writers#10){.+.+.+}, at: [<ffffffff815e0a8f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#10){.+.+.+}, at: [<ffffffff815e0a8f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#14){+.+.+.}, at: [<ffffffff8156a838>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#14){+.+.+.}, at: [<ffffffff8156a838>] do_truncate2+0x128/0x1f0 fs/open.c:61

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

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.113-g47bbcd6 #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d9777d08 ffffffff81eb32a9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9bd0 ffff8801d9777d40
 ffffffff81ebe5a7 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb32a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb32a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebe5a7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebe53a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9cd4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366cf4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366cf4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366cf4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366cf4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d0ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fa15c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 1 Comm: init Not tainted 4.9.113-g47bbcd6 #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d99b0000 task.stack: ffff8801d99b8000
RIP: 0010:[<ffffffff8214fb5b>] 
c [<ffffffff8214fb5b>] inb arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff8214fb5b>] 
c [<ffffffff8214fb5b>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:414
RSP: 0018:ffff8801d99bf520  EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff8214fb01 RDI: ffffffff864aae78
RBP: ffff8801d99bf530 R08: ffff8801d99b0938 R09: 0000000000000001
R10: ffff8801d99b0000 R11: 1ffff1003b336122 R12: ffffffff864aae40
R13: 0000000000000020 R14: fffffbfff0c9560f R15: fffffbfff0c955d1
FS:  00007f42666d97a0(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc8903a2188 CR3: 00000001cdaba000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff864aae40
c 000000000000270f
c ffff8801d99bf580
c ffffffff82151724
c
 ffff8801d99bf5b8
c ffffffff864aae88
c ffffffff864ab07a
c ffffffff864aae40
c
 0000000000000069
c ffffffff82151870
c dffffc0000000000
c 0000000000000069
c
Call Trace:
 [<ffffffff82151724>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 [<ffffffff82151724>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1998
 [<ffffffff8215188f>] serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3104
 [<ffffffff8213a0b9>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1859
 [<ffffffff8215daa8>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3170
 [<ffffffff8214a60f>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff8125bccd>] call_console_drivers.isra.18.constprop.28+0x1ad/0x360 kernel/printk/printk.c:1589
 [<ffffffff8125eacf>] console_unlock+0x42f/0xb40 kernel/printk/printk.c:2449
 [<ffffffff8125ff17>] console_device+0x97/0xc0 kernel/printk/printk.c:2557
 [<ffffffff821194da>] tty_lookup_driver drivers/tty/tty_io.c:2003 [inline]
 [<ffffffff821194da>] tty_open_by_driver drivers/tty/tty_io.c:2048 [inline]
 [<ffffffff821194da>] tty_open+0x71a/0xe20 drivers/tty/tty_io.c:2125
 [<ffffffff8157ee6d>] chrdev_open+0x22d/0x4c0 fs/char_dev.c:392
 [<ffffffff81569d53>] do_dentry_open+0x703/0xc80 fs/open.c:766
 [<ffffffff8156d53c>] vfs_open+0x11c/0x210 fs/open.c:879
 [<ffffffff815a4678>] do_last fs/namei.c:3410 [inline]
 [<ffffffff815a4678>] path_openat+0x758/0x3590 fs/namei.c:3534
 [<ffffffff815ab777>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8156df4d>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff8156e22d>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff8156e22d>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9f93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
c24 
cc9 
c00 
c00 
c00 
c49 
c8d 
c7c 
c24 
c38 
c48 
cb8 
c00 
c00 
c00 
c00 
c00 
cfc 
cff 
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c48 
c89 
cfa 
c48 
cc1 
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c03 
cd3 
ce3 
c80 
c3c 
c02 
c00 
c75 
c17 
c41 
c03 
c5c 
c24 
c38 
c89 
cda 
cec 
c<5b> 
c0f 
cb6 
cc0 
c41 
c5c 
c5d 
cc3 
ce8 
c58 
cc0 
c3e 
cff 
ceb 
cc2 
ce8 
cb1 
cc0 
c3e 
cff 
ceb 
c