device loop0 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
INFO: task syz-executor0:17699 blocked for more than 120 seconds.
      Not tainted 4.9.98-g9731a2d #19
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D30056 17699   3871 0x00000004
 ffff8801d4fc1800 ffff8801cd7c2a00 ffff8801d6e74fc0 ffff8801d84f4800
 ffff8801db221b98 ffff8801d0307aa8 ffffffff839e377d ffffffff81233817
 0000000000000000 ffff8801d4fc20c0 0000000600000007 ffff8801db222468
Call Trace:
 [<ffffffff839e4d7f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f03b8>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f03b8>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee51c7>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff8122a440>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff8122a440>] down_write_nested+0x60/0xa0 kernel/locking/rwsem.c:174
 [<ffffffff815a8131>] inode_lock_nested include/linux/fs.h:801 [inline]
 [<ffffffff815a8131>] do_unlinkat+0x2a1/0x680 fs/namei.c:4067
 [<ffffffff815a9fe9>] SYSC_unlinkat fs/namei.c:4123 [inline]
 [<ffffffff815a9fe9>] SyS_unlinkat+0x39/0x80 fs/namei.c:4115
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f4653>] 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: [<ffffffff813646ec>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646ec>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81423ba0>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3681:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d565c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3777:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f2822>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211cc12>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
2 locks held by syz-executor0/17699:
 #0:  (sb_writers#16){.+.+.+}, at: [<ffffffff815ddeff>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#16){.+.+.+}, at: [<ffffffff815ddeff>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#17/1){+.+.+.}, at: [<ffffffff815a8131>] inode_lock_nested include/linux/fs.h:801 [inline]
 #1:  (&sb->s_type->i_mutex_key#17/1){+.+.+.}, at: [<ffffffff815a8131>] do_unlinkat+0x2a1/0x680 fs/namei.c:4067
2 locks held by syz-executor0/17701:
 #0:  (sb_writers#16){.+.+.+}, at: [<ffffffff815ddeff>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#16){.+.+.+}, at: [<ffffffff815ddeff>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#17/1){+.+.+.}, at: [<ffffffff815a8131>] inode_lock_nested include/linux/fs.h:801 [inline]
 #1:  (&sb->s_type->i_mutex_key#17/1){+.+.+.}, at: [<ffffffff815a8131>] do_unlinkat+0x2a1/0x680 fs/namei.c:4067

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.98-g9731a2d #19
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d85a7d08 ffffffff81eb0ee9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b7da0 ffff8801d85a7d40
 ffffffff81ebc1e7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb0ee9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb0ee9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebc1e7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebc17a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b7ea4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81364c84>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81364c84>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81364c84>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81364c84>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ad5d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f481c>] 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: 17682 Comm: syz-executor0 Not tainted 4.9.98-g9731a2d #19
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff880194c4b000 task.stack: ffff8801cb688000
RIP: 0010:[<ffffffff8214d56b>] 
c [<ffffffff8214d56b>] inb arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff8214d56b>] 
c [<ffffffff8214d56b>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:414
RSP: 0018:ffff8801cb68ef30  EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff8214d511 RDI: ffffffff864aae78
RBP: ffff8801cb68ef40 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff864aae40
R13: 0000000000000020 R14: fffffbfff0c9560f R15: fffffbfff0c955d1
FS:  00007f63b6b94700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f49fd56a000 CR3: 00000001d36be000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff864aae40
c 0000000000002706
c ffff8801cb68ef90
c ffffffff8214f134
c
 ffffffff81edc1d8
c ffffffff864aae88
c ffffffff864ab07a
c ffffffff864aae40
c
 000000000000005d
c ffffffff8214f280
c dffffc0000000000
c 000000000000005d
c
Call Trace:
 [<ffffffff8214f134>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 [<ffffffff8214f134>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1997
 [<ffffffff8214f29f>] serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3103
 [<ffffffff82137ac9>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1859
 [<ffffffff8215b4a8>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3169
 [<ffffffff8214801f>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff81259e7d>] call_console_drivers.isra.18.constprop.28+0x1ad/0x360 kernel/printk/printk.c:1589
 [<ffffffff8125cc7f>] console_unlock+0x42f/0xb40 kernel/printk/printk.c:2449
 [<ffffffff8125d7d8>] vprintk_emit+0x448/0x790 kernel/printk/printk.c:1903
 [<ffffffff8125db48>] vprintk+0x28/0x30 kernel/printk/printk.c:1913
 [<ffffffff8125db6d>] vprintk_default+0x1d/0x30 kernel/printk/printk.c:1914
 [<ffffffff8142a975>] vprintk_func kernel/printk/internal.h:36 [inline]
 [<ffffffff8142a975>] printk+0xaf/0xd7 kernel/printk/printk.c:1975
 [<ffffffff81cb746a>] __find_get_block_slow.cold.57+0x37/0xf0 fs/buffer.c:238
 [<ffffffff81621a3e>] __find_get_block+0x23e/0x4c0 fs/buffer.c:1360
 [<ffffffff81622849>] __getblk_slow fs/buffer.c:1101 [inline]
 [<ffffffff81622849>] __getblk_gfp+0x189/0x710 fs/buffer.c:1386
 [<ffffffff816261ed>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff818b3f68>] sb_bread include/linux/buffer_head.h:300 [inline]
 [<ffffffff818b3f68>] fat__get_entry+0x4c8/0x8f0 fs/fat/dir.c:100
 [<ffffffff818b6bf1>] fat_get_entry fs/fat/dir.c:128 [inline]
 [<ffffffff818b6bf1>] fat_get_short_entry+0x131/0x2a0 fs/fat/dir.c:876
 [<ffffffff818b714d>] fat_scan+0xfd/0x340 fs/fat/dir.c:961
 [<ffffffff818de759>] msdos_find+0xf9/0x2d0 fs/fat/namei_msdos.c:128
 [<ffffffff818df075>] msdos_lookup+0x135/0x250 fs/fat/namei_msdos.c:208
 [<ffffffff8159889d>] lookup_open+0x63d/0x1930 fs/namei.c:3203
 [<ffffffff815a2508>] do_last fs/namei.c:3315 [inline]
 [<ffffffff815a2508>] path_openat+0xef8/0x3590 fs/namei.c:3534
 [<ffffffff815a8e67>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8156b63d>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff8156b960>] SYSC_openat fs/open.c:1099 [inline]
 [<ffffffff8156b960>] SyS_openat+0x30/0x40 fs/open.c:1093
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f4653>] 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 
c68 
cbd 
c3e 
cff 
ceb 
cc2 
ce8 
cc1 
cbd 
c3e 
cff 
ceb 
c