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-executor0:10193 blocked for more than 120 seconds.
      Not tainted 4.9.101-gaef17a5 #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D29112 10193   3805 0x00000004
 ffff8801d9534800 0000000000000000 ffff8801d536ef40 ffff8801d62d9800
 ffff8801db221b98 ffff8801d365f6f0 ffffffff839e39bd ffffffff81233857
 0000000000000000 ffff8801d95350c0 0000000600000007 ffff8801db222468
Call Trace:
 [<ffffffff839e4fbf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839ef3e4>] rwsem_down_read_failed+0x1e4/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81ee52b8>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff839ee312>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff839ee312>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff815924f1>] inode_lock_shared include/linux/fs.h:776 [inline]
 [<ffffffff815924f1>] lookup_slow+0x141/0x470 fs/namei.c:1645
 [<ffffffff8159eb76>] walk_component+0x716/0x1bb0 fs/namei.c:1784
 [<ffffffff815a14d6>] lookup_last fs/namei.c:2266 [inline]
 [<ffffffff815a14d6>] path_lookupat.isra.41+0x186/0x410 fs/namei.c:2283
 [<ffffffff815a6f87>] filename_lookup.part.55+0x177/0x370 fs/namei.c:2317
 [<ffffffff815a7343>] filename_lookup fs/namei.c:2310 [inline]
 [<ffffffff815a7343>] user_path_at_empty+0x53/0x70 fs/namei.c:2578
 [<ffffffff815aad64>] user_path_at include/linux/namei.h:55 [inline]
 [<ffffffff815aad64>] SYSC_linkat fs/namei.c:4314 [inline]
 [<ffffffff815aad64>] SyS_linkat fs/namei.c:4289 [inline]
 [<ffffffff815aad64>] SYSC_link fs/namei.c:4356 [inline]
 [<ffffffff815aad64>] SyS_link+0xd4/0x550 fs/namei.c:4354
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f4893>] 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: [<ffffffff8136477c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136477c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81423c90>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3607:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d57ac>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3703:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f2a62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211cd32>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor0/10193:
 #0:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815924f1>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815924f1>] lookup_slow+0x141/0x470 fs/namei.c:1645
2 locks held by syz-executor0/10195:
 #0:  (sb_writers#17){.+.+.+}, at: [<ffffffff815de04f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#17){.+.+.+}, at: [<ffffffff815de04f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815a2635>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815a2635>] do_last fs/namei.c:3312 [inline]
 #1:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815a2635>] path_openat+0xed5/0x3590 fs/namei.c:3534
1 lock held by syz-executor0/10198:
 #0:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815924f1>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815924f1>] lookup_slow+0x141/0x470 fs/namei.c:1645
2 locks held by syz-executor0/10201:
 #0:  (sb_writers#17){.+.+.+}, at: [<ffffffff815de04f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#17){.+.+.+}, at: [<ffffffff815de04f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815a2635>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815a2635>] do_last fs/namei.c:3312 [inline]
 #1:  (&sb->s_type->i_mutex_key#19){++++++}, at: [<ffffffff815a2635>] path_openat+0xed5/0x3590 fs/namei.c:3534
1 lock held by init/10205:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/10206:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/10207:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/10208:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/10209:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/10210:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff82116ddc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.101-gaef17a5 #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8617d08 ffffffff81eb1009 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b7da0 ffff8801d8617d40
 ffffffff81ebc307 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb1009>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb1009>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebc307>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebc29a>] 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
 [<ffffffff81364d14>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81364d14>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81364d14>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81364d14>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ad9d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f4a5c>] 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: 10138 Comm: syz-executor4 Not tainted 4.9.101-gaef17a5 #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d7f3b000 task.stack: ffff880191ee8000
RIP: 0010:[<ffffffff8214d68b>] 
c [<ffffffff8214d68b>] inb arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff8214d68b>] 
c [<ffffffff8214d68b>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:414
RSP: 0018:ffff880191eeee30  EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff8214d631 RDI: ffffffff864aae78
RBP: ffff880191eeee40 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff864aae40
R13: 0000000000000020 R14: fffffbfff0c9560f R15: fffffbfff0c955d1
FS:  00007fba507bb700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c42d2d5010 CR3: 00000001c1b84000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff864aae40
c 000000000000270d
c ffff880191eeee90
c ffffffff8214f254
c
 ffffffff81edc2f8
c ffffffff864aae88
c ffffffff864ab07a
c ffffffff864aae40
c
 0000000000000032
c ffffffff8214f3a0
c dffffc0000000000
c 0000000000000032
c
Call Trace:
 [<ffffffff8214f254>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 [<ffffffff8214f254>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1997
 [<ffffffff8214f3bf>] serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3103
 [<ffffffff82137be9>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1859
 [<ffffffff8215b5c8>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3169
 [<ffffffff8214813f>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff81259ebd>] call_console_drivers.isra.18.constprop.28+0x1ad/0x360 kernel/printk/printk.c:1589
 [<ffffffff8125ccbf>] console_unlock+0x42f/0xb40 kernel/printk/printk.c:2449
 [<ffffffff8125d818>] vprintk_emit+0x448/0x790 kernel/printk/printk.c:1903
 [<ffffffff8125db88>] vprintk+0x28/0x30 kernel/printk/printk.c:1913
 [<ffffffff8125dbad>] vprintk_default+0x1d/0x30 kernel/printk/printk.c:1914
 [<ffffffff8142aa65>] vprintk_func kernel/printk/internal.h:36 [inline]
 [<ffffffff8142aa65>] printk+0xaf/0xd7 kernel/printk/printk.c:1975
 [<ffffffff81f670db>] nla_parse.cold.10+0x27/0x2c lib/nlattr.c:205
 [<ffffffff83220c9c>] nla_parse_nested include/net/netlink.h:748 [inline]
 [<ffffffff83220c9c>] ctnetlink_parse_tuple+0x10c/0x740 net/netfilter/nf_conntrack_netlink.c:1024
 [<ffffffff8322384b>] ctnetlink_get_conntrack+0x2cb/0x770 net/netfilter/nf_conntrack_netlink.c:1219
 [<ffffffff831dd8e3>] nfnetlink_rcv_msg+0xa83/0xc80 net/netfilter/nfnetlink.c:212
 [<ffffffff831ce685>] netlink_rcv_skb+0x145/0x370 net/netlink/af_netlink.c:2358
 [<ffffffff831dc4dc>] nfnetlink_rcv+0x9cc/0x1100 net/netfilter/nfnetlink.c:474
 [<ffffffff831cd238>] netlink_unicast_kernel net/netlink/af_netlink.c:1278 [inline]
 [<ffffffff831cd238>] netlink_unicast+0x4d8/0x6f0 net/netlink/af_netlink.c:1304
 [<ffffffff831cdbe5>] netlink_sendmsg+0x795/0xc30 net/netlink/af_netlink.c:1852
 [<ffffffff83012fcc>] sock_sendmsg_nosec net/socket.c:635 [inline]
 [<ffffffff83012fcc>] sock_sendmsg+0xcc/0x110 net/socket.c:645
 [<ffffffff83014a6c>] ___sys_sendmsg+0x6fc/0x840 net/socket.c:1969
 [<ffffffff83016ad9>] __sys_sendmsg+0xd9/0x190 net/socket.c:2003
 [<ffffffff83016bbd>] SYSC_sendmsg net/socket.c:2014 [inline]
 [<ffffffff83016bbd>] SyS_sendmsg+0x2d/0x50 net/socket.c:2010
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f4893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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