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-executor0:3863 blocked for more than 140 seconds.
      Not tainted 4.9.124-g09eb2ba #31
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D26792  3863      1 0x00000004
 ffff8801d90a3000 0000000000000000 ffff8801bf48b9c0 ffffffff84629800
 ffff8801db221c18 ffff8801a94b74e0 ffffffff839f0afd ffffffff81237da7
 0000000000000000 ffff8801d90a38c0 0000000600000007 ffff8801db2224e8
Call Trace:
 [<ffffffff839f20ff>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839fc524>] rwsem_down_read_failed+0x1e4/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81eed8d8>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff839fb452>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff839fb452>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff81599441>] inode_lock_shared include/linux/fs.h:776 [inline]
 [<ffffffff81599441>] lookup_slow+0x141/0x470 fs/namei.c:1645
 [<ffffffff815a5ac6>] walk_component+0x716/0x1bb0 fs/namei.c:1784
 [<ffffffff815a77e9>] link_path_walk+0x889/0x1200 fs/namei.c:2120
 [<ffffffff815a885d>] path_openat+0x1ad/0x3590 fs/namei.c:3533
 [<ffffffff815aff07>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff815726dd>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff815729bd>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff815729bd>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff83a019d3>] 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: [<ffffffff813689dc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813689dc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81428248>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3677:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815dc7ec>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3773:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839ffba2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff82125402>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor0/3863:
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff81599441>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff81599441>] lookup_slow+0x141/0x470 fs/namei.c:1645
2 locks held by syz-executor0/17108:
 #0:  (sb_writers#11){.+.+.+}, at: [<ffffffff815e50cf>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#11){.+.+.+}, at: [<ffffffff815e50cf>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815a9585>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815a9585>] do_last fs/namei.c:3312 [inline]
 #1:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815a9585>] path_openat+0xed5/0x3590 fs/namei.c:3534
1 lock held by init/17142:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f80c>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f80c>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/17143:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f80c>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f80c>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/17144:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f80c>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f80c>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/17145:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f80c>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f80c>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/17146:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f80c>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f80c>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125

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

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.124-g09eb2ba #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d86c7d08 ffffffff81eb95e9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9fa0 ffff8801d86c7d40
 ffffffff81ec4927 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb95e9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb95e9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ec4927>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ec48ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810ba0a4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81368f74>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81368f74>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81368f74>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81368f74>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119f3cd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff83a01b9c>] 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: 17141 Comm: init Not tainted 4.9.124-g09eb2ba #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801ba950000 task.stack: ffff8801cef08000
RIP: 0010:[<ffffffff821561db>] 
c [<ffffffff821561db>] inb arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff821561db>] 
c [<ffffffff821561db>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:413
RSP: 0018:ffff8801cef0f520  EFLAGS: 00000002
RAX: dffffc0000000020 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff82156181 RDI: ffffffff864ace78
RBP: ffff8801cef0f530 R08: ffff8801ba950938 R09: 0000000000000001
R10: ffff8801ba950000 R11: 1ffff1003752a122 R12: ffffffff864ace40
R13: 0000000000000020 R14: fffffbfff0c95a0f R15: fffffbfff0c959d1
FS:  00007fca15f757a0(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff703639000 CR3: 00000001bd0f3000 CR4: 00000000001606f0
DR0: 00000000200001c0 DR1: 00000000200001c0 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff864ace40
c 0000000000002707
c ffff8801cef0f580
c ffffffff82157da4
c
 ffff8801cef0f5b8
c ffffffff864ace88
c ffffffff864ad07a
c ffffffff864ace40
c
 0000000000000039
c ffffffff82157ef0
c dffffc0000000000
c 0000000000000039
c
Call Trace:
 [<ffffffff82157da4>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 [<ffffffff82157da4>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1997
 [<ffffffff82157f0f>] serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3103
 [<ffffffff82140739>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1859
 [<ffffffff82164128>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3169
 [<ffffffff82150c8f>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff8125decd>] call_console_drivers.isra.18.constprop.28+0x1ad/0x360 kernel/printk/printk.c:1589
 [<ffffffff81260ccf>] console_unlock+0x42f/0xb40 kernel/printk/printk.c:2449
 [<ffffffff81262117>] console_device+0x97/0xc0 kernel/printk/printk.c:2557
 [<ffffffff8211faba>] tty_lookup_driver drivers/tty/tty_io.c:2003 [inline]
 [<ffffffff8211faba>] tty_open_by_driver drivers/tty/tty_io.c:2048 [inline]
 [<ffffffff8211faba>] tty_open+0x71a/0xe20 drivers/tty/tty_io.c:2125
 [<ffffffff815835fd>] chrdev_open+0x22d/0x4c0 fs/char_dev.c:392
 [<ffffffff8156e4e3>] do_dentry_open+0x703/0xc80 fs/open.c:766
 [<ffffffff81571ccc>] vfs_open+0x11c/0x210 fs/open.c:879
 [<ffffffff815a8e08>] do_last fs/namei.c:3410 [inline]
 [<ffffffff815a8e08>] path_openat+0x758/0x3590 fs/namei.c:3534
 [<ffffffff815aff07>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff815726dd>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff815729bd>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff815729bd>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff83a019d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
c24 
cc9 
c00 
c00 
c00 
c49 
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c7c 
c24 
c38 
c48 
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c48 
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cc1 
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c80 
c3c 
c02 
c00 
c75 
c17 
c41 
c03 
c5c 
c24 
c38 
c89 
cda 
cec 
c<5b> 
c0f 
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c41 
c5c 
c5d 
cc3 
ce8 
c98 
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cff 
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cc2 
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c