b_state=0x00000029, b_size=512
device loop0 blocksize: 2048
__find_get_block_slow() failed. block=2, b_blocknr=8
b_state=0x00000029, b_size=512
device loop0 blocksize: 2048
INFO: task syz-executor0:25978 blocked for more than 140 seconds.
      Not tainted 4.9.119-g9dc978d #23
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D29656 25978  22061 0x00000004
 ffff88019ba9b000 ffff8801c7fcf9c0 ffff8801d89b5500 ffff8801d4406000
 ffff8801db221c18 ffff88019a71f808 ffffffff839ebdcd ffffffff81235627
 0000000000000000 ffff88019ba9b8c0 0000000600000007 ffff8801db2224e8
Call Trace:
 [<ffffffff839ed3cf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839f8a08>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f8a08>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee8ec7>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839f67dc>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839f67dc>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff815a51a5>] inode_lock include/linux/fs.h:766 [inline]
 [<ffffffff815a51a5>] do_last fs/namei.c:3312 [inline]
 [<ffffffff815a51a5>] path_openat+0xed5/0x3590 fs/namei.c:3534
 [<ffffffff815abb27>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8156e2fd>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff8156e5dd>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff8156e5dd>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fccd3>] 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: [<ffffffff813667bc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813667bc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81426027>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3770:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839fae72>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff821208d2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor0/25978:
 #0:  (sb_writers#11){.+.+.+}, at: [<ffffffff815e0e3f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#11){.+.+.+}, at: [<ffffffff815e0e3f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#17){++++++}, at: [<ffffffff815a51a5>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#17){++++++}, at: [<ffffffff815a51a5>] do_last fs/namei.c:3312 [inline]
 #1:  (&sb->s_type->i_mutex_key#17){++++++}, at: [<ffffffff815a51a5>] path_openat+0xed5/0x3590 fs/namei.c:3534
2 locks held by syz-executor0/25980:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d859c>] __fdget_pos+0xac/0xd0 fs/file.c:781
 #1:  (&sb->s_type->i_mutex_key#17){++++++}, at: [<ffffffff815b4213>] inode_lock_shared include/linux/fs.h:776 [inline]
 #1:  (&sb->s_type->i_mutex_key#17){++++++}, at: [<ffffffff815b4213>] iterate_dir+0xc3/0x600 fs/readdir.c:39
1 lock held by init/25991:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211acdc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211acdc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/25992:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211acdc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211acdc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/25993:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211acdc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211acdc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/25994:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211acdc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211acdc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/25995:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211acdc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211acdc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.119-g9dc978d #23
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d842fd08 ffffffff81eb4be9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9bd0 ffff8801d842fd40
 ffffffff81ebfee7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb4be9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb4be9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebfee7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebfe7a>] 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
 [<ffffffff81366d54>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366d54>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366d54>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366d54>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d0ed>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fce9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 25990 Comm: init Not tainted 4.9.119-g9dc978d #23
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801b9aa1800 task.stack: ffff880199a28000
RIP: 0010:[<ffffffff821516ab>] 
c [<ffffffff821516ab>] inb arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff821516ab>] 
c [<ffffffff821516ab>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:414
RSP: 0018:ffff880199a2f520  EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff82151651 RDI: ffffffff864aaeb8
RBP: ffff880199a2f530 R08: ffff8801b9aa2138 R09: 0000000000000001
R10: ffff8801b9aa1800 R11: 1ffff10037354422 R12: ffffffff864aae80
R13: 0000000000000020 R14: fffffbfff0c95617 R15: fffffbfff0c955d9
FS:  00007fa840a147a0(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001ce8158 CR3: 00000001d7188000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff864aae80
c 000000000000270e
c ffff880199a2f580
c ffffffff82153274
c
 ffff880199a2f5b8
c ffffffff864aaec8
c ffffffff864ab0ba
c ffffffff864aae80
c
 0000000000000065
c ffffffff821533c0
c dffffc0000000000
c 0000000000000065
c
Call Trace:
 [<ffffffff82153274>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 [<ffffffff82153274>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1998
 [<ffffffff821533df>] serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3104
 [<ffffffff8213bc09>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1859
 [<ffffffff8215f5f8>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3170
 [<ffffffff8214c15f>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff8125bcad>] call_console_drivers.isra.18.constprop.28+0x1ad/0x360 kernel/printk/printk.c:1589
 [<ffffffff8125eaaf>] console_unlock+0x42f/0xb40 kernel/printk/printk.c:2449
 [<ffffffff8125fef7>] console_device+0x97/0xc0 kernel/printk/printk.c:2557
 [<ffffffff8211af8a>] tty_lookup_driver drivers/tty/tty_io.c:2003 [inline]
 [<ffffffff8211af8a>] tty_open_by_driver drivers/tty/tty_io.c:2048 [inline]
 [<ffffffff8211af8a>] tty_open+0x71a/0xe20 drivers/tty/tty_io.c:2125
 [<ffffffff8157f21d>] chrdev_open+0x22d/0x4c0 fs/char_dev.c:392
 [<ffffffff8156a103>] do_dentry_open+0x703/0xc80 fs/open.c:766
 [<ffffffff8156d8ec>] vfs_open+0x11c/0x210 fs/open.c:879
 [<ffffffff815a4a28>] do_last fs/namei.c:3410 [inline]
 [<ffffffff815a4a28>] path_openat+0x758/0x3590 fs/namei.c:3534
 [<ffffffff815abb27>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8156e2fd>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff8156e5dd>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff8156e5dd>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fccd3>] 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 
cdf 
c48 
c89 
cfa 
c48 
cc1 
cea 
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 
ce8 
ca7 
c3e 
cff 
ceb 
cc2 
ce8 
c41 
ca8 
c3e 
cff 
ceb 
c