b_state=0x0000002b, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x0000002b, b_size=512
device loop0 blocksize: 4096
INFO: task syz-executor0:9118 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   D27928  9118      1 0x00000004
 ffff8801998fc800 ffff8801ca06af40 ffff8801d4d64540 ffff8801cfb8c800
 ffff8801db321c18 ffff8801d03a7b40 ffffffff839ebdcd 0000000000000002
 0000000041b58ab3 ffffffff843bc37b 00ffffff81221590 ffff8801db3224e8
Call Trace:
 [<ffffffff839ed3cf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff81603039>] wb_wait_for_completion+0x149/0x1b0 fs/fs-writeback.c:221
 [<ffffffff816032a7>] __writeback_inodes_sb_nr+0x207/0x300 fs/fs-writeback.c:2310
 [<ffffffff816033f7>] writeback_inodes_sb_nr fs/fs-writeback.c:2327 [inline]
 [<ffffffff816033f7>] writeback_inodes_sb+0x27/0x30 fs/fs-writeback.c:2342
 [<ffffffff8161afb3>] __sync_filesystem fs/sync.c:35 [inline]
 [<ffffffff8161afb3>] sync_filesystem+0x93/0x240 fs/sync.c:63
 [<ffffffff815799e5>] generic_shutdown_super+0x75/0x300 fs/super.c:423
 [<ffffffff8157a31f>] kill_block_super+0x9f/0x120 fs/super.c:1127
 [<ffffffff8157a695>] deactivate_locked_super+0x75/0xd0 fs/super.c:310
 [<ffffffff8157b0a1>] deactivate_super+0x91/0xd0 fs/super.c:341
 [<ffffffff815dd442>] cleanup_mnt+0xb2/0x160 fs/namespace.c:1134
 [<ffffffff815dd576>] __cleanup_mnt+0x16/0x20 fs/namespace.c:1141
 [<ffffffff8119838c>] task_work_run+0x10c/0x180 kernel/task_work.c:116
 [<ffffffff8100559c>] tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 arch/x86/entry/common.c:161
 [<ffffffff810064d4>] prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline]
 [<ffffffff810064d4>] syscall_return_slowpath arch/x86/entry/common.c:260 [inline]
 [<ffffffff810064d4>] do_syscall_64+0x364/0x490 arch/x86/entry/common.c:287
 [<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
1 lock held by rsyslogd/3679:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d859c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3775:
 #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
1 lock held by syz-executor0/9118:
 #0:  (&type->s_umount_key#48){+.+...}, at: [<ffffffff8157b099>] deactivate_super+0x89/0xd0 fs/super.c:340
1 lock held by init/9991:
 #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/9992:
 #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/9993:
 #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/9994:
 #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/9995:
 #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/9996:
 #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
 ffff8801d858fd08 ffffffff81eb4be9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9bd0 ffff8801d858fd40
 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: 9927 Comm: syz-executor4 Not tainted 4.9.119-g9dc978d #23
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d3bc6000 task.stack: ffff88019d630000
RIP: 0010:[<ffffffff811bbf52>] 
c [<ffffffff811bbf52>] preempt_count arch/x86/include/asm/preempt.h:22 [inline]
RIP: 0010:[<ffffffff811bbf52>] 
c [<ffffffff811bbf52>] preempt_count_add+0x52/0x170 kernel/sched/core.c:3246
RSP: 0018:ffff88019d6372b8  EFLAGS: 00000046
RAX: 0000000080000002 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81f1c62b RDI: ffffffff85b2d6c0
RBP: ffff88019d6372c8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 000000e7001763ff
R13: 00000000000008fd R14: 0000000000000001 R15: fffffbfff0c955d9
FS:  00007f3b13781700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001c0bb10 CR3: 00000001cd113000 CR4: 00000000001606f0
Stack:
 000000e70017693d
c 000000e7001763ff
c ffff88019d6372f8
c ffffffff81ee3d5d
c
 ffffffff864aae80
c 000000000000270c
c 0000000000000020
c fffffbfff0c95617
c
 ffff88019d637308
c ffffffff81ee3c91
c ffff88019d637358
c ffffffff8215324f
c
Call Trace:
 [<ffffffff81ee3d5d>] delay_tsc+0x3d/0xc0 arch/x86/lib/delay.c:67
 [<ffffffff81ee3c91>] __delay arch/x86/lib/delay.c:160 [inline]
 [<ffffffff81ee3c91>] __const_udelay+0x31/0x40 arch/x86/lib/delay.c:174
 [<ffffffff8215324f>] wait_for_xmitr+0x6f/0x1e0 drivers/tty/serial/8250/8250_port.c:2006
 [<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
 [<ffffffff8125f608>] vprintk_emit+0x448/0x790 kernel/printk/printk.c:1903
 [<ffffffff8125f978>] vprintk+0x28/0x30 kernel/printk/printk.c:1913
 [<ffffffff8125f99d>] vprintk_default+0x1d/0x30 kernel/printk/printk.c:1914
 [<ffffffff8142cdfc>] vprintk_func kernel/printk/internal.h:36 [inline]
 [<ffffffff8142cdfc>] printk+0xaf/0xd7 kernel/printk/printk.c:1975
 [<ffffffff81cc00e4>] fat_msg+0xdc/0x110 fs/fat/misc.c:54
 [<ffffffff81cbfa54>] parse_options.cold.27+0x4a/0x71 fs/fat/inode.c:1340
 [<ffffffff818d0e2d>] fat_fill_super+0x28d/0x3580 fs/fat/inode.c:1626
 [<ffffffff818d9681>] vfat_fill_super+0x31/0x40 fs/fat/namei_vfat.c:1070
 [<ffffffff8157c8d7>] mount_bdev+0x2c7/0x390 fs/super.c:1100
 [<ffffffff818d9644>] vfat_mount+0x34/0x40 fs/fat/namei_vfat.c:1077
 [<ffffffff8157e65c>] mount_fs+0x28c/0x370 fs/super.c:1206
 [<ffffffff815dde81>] vfs_kern_mount.part.29+0xd1/0x3d0 fs/namespace.c:991
 [<ffffffff815e57a9>] vfs_kern_mount fs/namespace.c:973 [inline]
 [<ffffffff815e57a9>] do_new_mount fs/namespace.c:2513 [inline]
 [<ffffffff815e57a9>] do_mount+0x3c9/0x2740 fs/namespace.c:2835
 [<ffffffff815e84fe>] SYSC_mount fs/namespace.c:3051 [inline]
 [<ffffffff815e84fe>] SyS_mount+0xfe/0x110 fs/namespace.c:3028
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fccd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
cf8 
c83 
ce0 
c07 
c83 
cc0 
c03 
c38 
cd0 
c7c 
c08 
c84 
cd2 
c0f 
c85 
c0d 
c01 
c00 
c00 
c8b 
c15 
c80 
c17 
c97 
c04 
c65 
c01 
c1d 
c09 
cbe 
ce5 
c7e 
c85 
cd2 
c75 
c11 
c65 
c8b 
c05 
cfe 
cbd 
ce5 
c7e 
c<0f> 
cb6 
cc0 
c3d 
cf4 
c00 
c00 
c00 
c7f 
c7f 
c65 
c8b 
c05 
ced 
cbd 
ce5 
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c25 
cff 
cff 
cff 
c