b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop0 blocksize: 4096
INFO: task syz-executor0:1060 blocked for more than 120 seconds.
      Not tainted 4.9.98-gf679e4d #14
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D28504  1060   3868 0x00000004
 ffff88019696c800 ffff8801921d1a40 ffff8801854e4000 ffff880188cbb000
 ffff8801db321b98 ffff880195d37690 ffffffff839e375d ffffffff81233817
 0000000000000000 ffff88019696d0c0 0000000600000007 ffff8801db322468
Call Trace:
 [<ffffffff839e4d5f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839ef184>] rwsem_down_read_failed+0x1e4/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81ee5278>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff839ee0b2>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff839ee0b2>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff815924e1>] inode_lock_shared include/linux/fs.h:776 [inline]
 [<ffffffff815924e1>] lookup_slow+0x141/0x470 fs/namei.c:1645
 [<ffffffff8159eb66>] walk_component+0x716/0x1bb0 fs/namei.c:1784
 [<ffffffff815a14c6>] lookup_last fs/namei.c:2266 [inline]
 [<ffffffff815a14c6>] path_lookupat.isra.41+0x186/0x410 fs/namei.c:2283
 [<ffffffff815a6f77>] filename_lookup.part.55+0x177/0x370 fs/namei.c:2317
 [<ffffffff815a7333>] filename_lookup fs/namei.c:2310 [inline]
 [<ffffffff815a7333>] user_path_at_empty+0x53/0x70 fs/namei.c:2578
 [<ffffffff815e2714>] user_path include/linux/namei.h:60 [inline]
 [<ffffffff815e2714>] do_mount+0x134/0x2740 fs/namespace.c:2780
 [<ffffffff815e56fe>] SYSC_mount fs/namespace.c:3051 [inline]
 [<ffffffff815e56fe>] SyS_mount+0xfe/0x110 fs/namespace.c:3028
 [<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/520:
 #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: [<ffffffff81423ce0>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3769:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f2802>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff8211ccf2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor0/1060:
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815924e1>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815924e1>] lookup_slow+0x141/0x470 fs/namei.c:1645
1 lock held by syz-executor0/1074:
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815dee5c>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815dee5c>] lock_mount+0x8c/0x2c0 fs/namespace.c:2077
1 lock held by syz-executor0/1076:
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815924e1>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815924e1>] lookup_slow+0x141/0x470 fs/namei.c:1645
1 lock held by syz-executor0/1084:
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815dee5c>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815dee5c>] lock_mount+0x8c/0x2c0 fs/namespace.c:2077
1 lock held by syz-executor0/1086:
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815dee5c>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815dee5c>] lock_mount+0x8c/0x2c0 fs/namespace.c:2077

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

NMI backtrace for cpu 1
CPU: 1 PID: 520 Comm: khungtaskd Not tainted 4.9.98-gf679e4d #14
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8af7d08 ffffffff81eb0fc9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b7da0 ffff8801d8af7d40
 ffffffff81ebc2c7 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb0fc9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb0fc9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebc2c7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebc25a>] 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 1065 Comm: syz-executor0 Not tainted 4.9.98-gf679e4d #14
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9108000 task.stack: ffff8801b9708000
RIP: 0010:[<ffffffff8214d64b>] 
c [<ffffffff8214d64b>] inb arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff8214d64b>] 
c [<ffffffff8214d64b>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:414
RSP: 0018:ffff8801b970edd8  EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff8214d5f1 RDI: ffffffff864aae78
RBP: ffff8801b970ede8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff864aae40
R13: 0000000000000020 R14: fffffbfff0c9560f R15: fffffbfff0c955d1
FS:  00007f5b4c725700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001077000 CR3: 00000001d301d000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff864aae40
c 0000000000002708
c ffff8801b970ee38
c ffffffff8214f214
c
 ffffffff81edc2b8
c ffffffff864aae88
c ffffffff864ab07a
c ffffffff864aae40
c
 0000000000000032
c ffffffff8214f360
c dffffc0000000000
c 0000000000000032
c
Call Trace:
 [<ffffffff8214f214>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 [<ffffffff8214f214>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1997
 [<ffffffff8214f37f>] serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3103
 [<ffffffff82137ba9>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1859
 [<ffffffff8215b588>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3169
 [<ffffffff821480ff>] 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
 [<ffffffff8142aab5>] vprintk_func kernel/printk/internal.h:36 [inline]
 [<ffffffff8142aab5>] printk+0xaf/0xd7 kernel/printk/printk.c:1975
 [<ffffffff81cb75d0>] __find_get_block_slow.cold.57+0xcd/0xf0 fs/buffer.c:244
 [<ffffffff81621b7e>] __find_get_block+0x23e/0x4c0 fs/buffer.c:1360
 [<ffffffff81622989>] __getblk_slow fs/buffer.c:1101 [inline]
 [<ffffffff81622989>] __getblk_gfp+0x189/0x710 fs/buffer.c:1386
 [<ffffffff8162632d>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff818b40a8>] sb_bread include/linux/buffer_head.h:300 [inline]
 [<ffffffff818b40a8>] fat__get_entry+0x4c8/0x8f0 fs/fat/dir.c:100
 [<ffffffff818b6d31>] fat_get_entry fs/fat/dir.c:128 [inline]
 [<ffffffff818b6d31>] fat_get_short_entry+0x131/0x2a0 fs/fat/dir.c:876
 [<ffffffff818b728d>] fat_scan+0xfd/0x340 fs/fat/dir.c:961
 [<ffffffff818de899>] msdos_find+0xf9/0x2d0 fs/fat/namei_msdos.c:128
 [<ffffffff818df1b5>] msdos_lookup+0x135/0x250 fs/fat/namei_msdos.c:208
 [<ffffffff815925de>] lookup_slow+0x23e/0x470 fs/namei.c:1668
 [<ffffffff8159eb66>] walk_component+0x716/0x1bb0 fs/namei.c:1784
 [<ffffffff815a14c6>] lookup_last fs/namei.c:2266 [inline]
 [<ffffffff815a14c6>] path_lookupat.isra.41+0x186/0x410 fs/namei.c:2283
 [<ffffffff815a6f77>] filename_lookup.part.55+0x177/0x370 fs/namei.c:2317
 [<ffffffff815a71b5>] filename_lookup fs/namei.c:2310 [inline]
 [<ffffffff815a71b5>] kern_path+0x45/0x70 fs/namei.c:2406
 [<ffffffff81631062>] lookup_bdev.part.25+0x72/0x180 fs/block_dev.c:1901
 [<ffffffff816311ce>] lookup_bdev+0x5e/0x80 fs/block_dev.c:1922
 [<ffffffff816c85fa>] quotactl_block fs/quota/quota.c:808 [inline]
 [<ffffffff816c85fa>] SYSC_quotactl fs/quota/quota.c:867 [inline]
 [<ffffffff816c85fa>] SyS_quotactl+0x1ba/0x1240 fs/quota/quota.c:832
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f4653>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
c24 
cc9 
c00 
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c<5b> 
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c