FAT-fs (loop3): Invalid FSINFO signature: 0x00000000, 0x00000000 (sector = 1)
FAT-fs (loop1): Invalid FSINFO signature: 0x00000000, 0x00000000 (sector = 1)
INFO: task syz-executor0:8869 blocked for more than 140 seconds.
      Not tainted 4.9.123-g520d10d3 #29
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D29368  8869  29181 0x00000004
 ffff88019f20b000 ffff8801b3c01a40 ffff8801b51f24c0 ffff8801af17e000
 ffff8801db321c18 ffff8801ad0977f8 ffffffff839f0ebd ffffffff81237907
 0000000000000000 ffff88019f20b8c0 0000000600000007 ffff8801db3224e8
Call Trace:
 [<ffffffff839f24bf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839fdaf8>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839fdaf8>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81eed9a7>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839fb8cc>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839fb8cc>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff815a9625>] inode_lock include/linux/fs.h:766 [inline]
 [<ffffffff815a9625>] do_last fs/namei.c:3312 [inline]
 [<ffffffff815a9625>] path_openat+0xed5/0x3590 fs/namei.c:3534
 [<ffffffff815affa7>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8157277d>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff81572aa0>] SYSC_openat fs/open.c:1099 [inline]
 [<ffffffff81572aa0>] SyS_openat+0x30/0x40 fs/open.c:1093
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff83a01d93>] 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: [<ffffffff81368a9c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81368a9c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81428308>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by rs:main Q:Reg/3663:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815dc88c>] __fdget_pos+0xac/0xd0 fs/file.c:781
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff815774fe>] file_start_write include/linux/fs.h:2640 [inline]
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff815774fe>] vfs_write+0x3ae/0x530 fs/read_write.c:556
1 lock held by rsyslogd/3665:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815dc88c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3761:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839fff62>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff821253c2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor0/8869:
 #0:  (sb_writers#17){.+.+.+}, at: [<ffffffff815e516f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#17){.+.+.+}, at: [<ffffffff815e516f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#24){++++++}, at: [<ffffffff815a9625>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#24){++++++}, at: [<ffffffff815a9625>] do_last fs/namei.c:3312 [inline]
 #1:  (&sb->s_type->i_mutex_key#24){++++++}, at: [<ffffffff815a9625>] path_openat+0xed5/0x3590 fs/namei.c:3534
1 lock held by init/8934:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f7cc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff8211f7cc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/8935:
 #0:  (sb_writers#3){.+.+.+}, at: [<ffffffff815774fe>] file_start_write include/linux/fs.h:2640 [inline]
 #0:  (sb_writers#3){.+.+.+}, at: [<ffffffff815774fe>] vfs_write+0x3ae/0x530 fs/read_write.c:556

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.123-g520d10d3 #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8627d08 ffffffff81eb9689 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9fa0 ffff8801d8627d40
 ffffffff81ec49c7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb9689>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb9689>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ec49c7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ec495a>] 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
 [<ffffffff81369034>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81369034>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81369034>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81369034>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119f3cd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff83a01f5c>] 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: 8936 Comm: init Not tainted 4.9.123-g520d10d3 #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88019a5c6000 task.stack: ffff880193c68000
RIP: 0010:[<ffffffff8215619b>] 
c [<ffffffff8215619b>] inb arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff8215619b>] 
c [<ffffffff8215619b>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:413
RSP: 0018:ffff880193c6f520  EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff82156141 RDI: ffffffff864ace78
RBP: ffff880193c6f530 R08: ffff88019a5c6938 R09: 0000000000000001
R10: ffff88019a5c6000 R11: 1ffff100334b8d22 R12: ffffffff864ace40
R13: 0000000000000020 R14: fffffbfff0c95a0f R15: fffffbfff0c959d1
FS:  00007f77fb1607a0(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f77fa873a30 CR3: 00000001bdc13000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff864ace40
c 000000000000270e
c ffff880193c6f580
c ffffffff82157d64
c
 ffff880193c6f5b8
c ffffffff864ace88
c ffffffff864ad07a
c ffffffff864ace40
c
 0000000000000033
c ffffffff82157eb0
c dffffc0000000000
c 0000000000000033
c
Call Trace:
 [<ffffffff82157d64>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 [<ffffffff82157d64>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1997
 [<ffffffff82157ecf>] serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3103
 [<ffffffff821406f9>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1859
 [<ffffffff821640e8>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3169
 [<ffffffff82150c4f>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff8125df8d>] call_console_drivers.isra.18.constprop.28+0x1ad/0x360 kernel/printk/printk.c:1589
 [<ffffffff81260d8f>] console_unlock+0x42f/0xb40 kernel/printk/printk.c:2449
 [<ffffffff812621d7>] console_device+0x97/0xc0 kernel/printk/printk.c:2557
 [<ffffffff8211fa7a>] tty_lookup_driver drivers/tty/tty_io.c:2003 [inline]
 [<ffffffff8211fa7a>] tty_open_by_driver drivers/tty/tty_io.c:2048 [inline]
 [<ffffffff8211fa7a>] tty_open+0x71a/0xe20 drivers/tty/tty_io.c:2125
 [<ffffffff8158369d>] chrdev_open+0x22d/0x4c0 fs/char_dev.c:392
 [<ffffffff8156e583>] do_dentry_open+0x703/0xc80 fs/open.c:766
 [<ffffffff81571d6c>] vfs_open+0x11c/0x210 fs/open.c:879
 [<ffffffff815a8ea8>] do_last fs/namei.c:3410 [inline]
 [<ffffffff815a8ea8>] path_openat+0x758/0x3590 fs/namei.c:3534
 [<ffffffff815affa7>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8157277d>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff81572a5d>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff81572a5d>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff83a01d93>] 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 
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c03 
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ce3 
c80 
c3c 
c02 
c00 
c75 
c17 
c41 
c03 
c5c 
c24 
c38 
c89 
cda 
cec 
c<5b> 
c0f 
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cc0 
c41 
c5c 
c5d 
cc3 
ce8 
c78 
c99 
c3e 
cff 
ceb 
cc2 
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cd1 
c99 
c3e 
cff 
ceb 
c