FAT-fs (loop6): error, fat_get_cluster: invalid cluster chain (i_pos 1041)
FAT-fs (loop6): Filesystem has been set read-only
FAT-fs (loop6): error, fat_get_cluster: invalid cluster chain (i_pos 1041)
FAT-fs (loop6): error, fat_get_cluster: invalid cluster chain (i_pos 1041)
INFO: task syz-executor0:10400 blocked for more than 120 seconds.
      Not tainted 4.9.105-gd7e64f8 #40
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D29704 10400   3872 0x00000004
 ffff8801d0036000 0000000000000000 ffff8801c38f1f80 ffff8801d9a6b000
 ffff8801db321c18 ffff88018a78fce8 ffffffff839e8c1d ffff8801d00368c8
 ffffed003a006d18 ffff8801d0036000 00fffc0000000000 ffff8801db3224e8
Call Trace:
 [<ffffffff839ea21f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839eaba3>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3590
 [<ffffffff839ef026>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff839ef026>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff815d83fc>] __fdget_pos+0xac/0xd0 fs/file.c:781
 [<ffffffff81576aee>] fdget_pos include/linux/file.h:66 [inline]
 [<ffffffff81576aee>] SYSC_write fs/read_write.c:599 [inline]
 [<ffffffff81576aee>] SyS_write+0x7e/0x1c0 fs/read_write.c:596
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9b13>] 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: [<ffffffff81366b9c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81366b9c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81426180>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by rs:main Q:Reg/3671:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d83fc>] __fdget_pos+0xac/0xd0 fs/file.c:781
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff81572f3e>] file_start_write include/linux/fs.h:2640 [inline]
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff81572f3e>] vfs_write+0x3ae/0x530 fs/read_write.c:556
2 locks held by getty/3769:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f7cc2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff82120062>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor0/10400:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d83fc>] __fdget_pos+0xac/0xd0 fs/file.c:781

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

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.105-gd7e64f8 #40
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8b0fd08 ffffffff81eb41a9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b96a0 ffff8801d8b0fd40
 ffffffff81ebf4a7 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb41a9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb41a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebf4a7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebf43a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b97a4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81367134>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81367134>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81367134>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81367134>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f9cdc>] 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: 10377 Comm: syz-executor0 Not tainted 4.9.105-gd7e64f8 #40
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801bbf14800 task.stack: ffff88017e850000
RIP: 0010:[<ffffffff81230120>] 
c [<ffffffff81230120>] match_held_lock+0x20/0x570 kernel/locking/lockdep.c:3404
RSP: 0018:ffff88017e856fc0  EFLAGS: 00000086
RAX: dffffc0000000000 RBX: ffff8801bbf14800 RCX: ffffc90000996000
RDX: ffff8801bbf150d8 RSI: ffffffff846deea0 RDI: ffff8801bbf150d8
RBP: ffff88017e856fe0 R08: ffff8801bbf15160 R09: 0000000000000001
R10: 0000000000000000 R11: 1ffff100377e2a27 R12: ffffed00377e2a18
R13: ffff8801bbf150c8 R14: ffffffff846deea0 R15: 0000000000000000
FS:  00007fbbed22d700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6c5cff5000 CR3: 00000001b88d9000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffed00377e2a18
c ffff8801bbf150c8
c ffffffff846deea0
c 0000000000000000
c
 ffff88017e857020
c ffffffff81230712
c ffff8801bbf150c0
c 0000000000000246
c
 ffff8801bbf14800
c ffffffff846deea0
c 00000000000001c4
c ffff8801d9c16548
c
Call Trace:
 [<ffffffff81230712>] __lock_is_held+0xa2/0xf0 kernel/locking/lockdep.c:3597
 [<ffffffff81230f44>] lock_is_held+0xb4/0x140 kernel/locking/lockdep.c:3794
 [<ffffffff811bb4f7>] ___might_sleep+0x1c7/0x260 kernel/sched/core.c:7958
 [<ffffffff811bb625>] __might_sleep+0x95/0x1a0 kernel/sched/core.c:7949
 [<ffffffff8143a75d>] lock_page include/linux/pagemap.h:452 [inline]
 [<ffffffff8143a75d>] pagecache_get_page+0x3bd/0x720 mm/filemap.c:1216
 [<ffffffff81625669>] find_or_create_page include/linux/pagemap.h:309 [inline]
 [<ffffffff81625669>] grow_dev_page fs/buffer.c:1005 [inline]
 [<ffffffff81625669>] grow_buffers fs/buffer.c:1078 [inline]
 [<ffffffff81625669>] __getblk_slow fs/buffer.c:1105 [inline]
 [<ffffffff81625669>] __getblk_gfp+0x249/0x710 fs/buffer.c:1386
 [<ffffffff818c3b55>] sb_getblk include/linux/buffer_head.h:318 [inline]
 [<ffffffff818c3b55>] fat_mirror_bhs+0x1a5/0x3f0 fs/fat/fatent.c:387
 [<ffffffff818c6da8>] fat_alloc_clusters+0xb58/0xe10 fs/fat/fatent.c:539
 [<ffffffff818d393f>] fat_add_cluster+0x6f/0xe0 fs/fat/inode.c:100
 [<ffffffff818d3c8f>] __fat_get_block fs/fat/inode.c:147 [inline]
 [<ffffffff818d3c8f>] fat_get_block+0x2df/0x800 fs/fat/inode.c:176
 [<ffffffff8162a191>] __block_write_begin_int+0x391/0x1040 fs/buffer.c:1987
 [<ffffffff8162aedf>] __block_write_begin fs/buffer.c:2038 [inline]
 [<ffffffff8162aedf>] block_write_begin+0x5f/0x180 fs/buffer.c:2097
 [<ffffffff8162b4f3>] cont_write_begin+0x4f3/0x810 fs/buffer.c:2450
 [<ffffffff818cfdfa>] fat_write_begin+0x9a/0x120 fs/fat/inode.c:222
 [<ffffffff81436151>] generic_perform_write+0x301/0x510 mm/filemap.c:2740
 [<ffffffff8143db2a>] __generic_file_write_iter+0x29a/0x540 mm/filemap.c:2833
 [<ffffffff8143e0b0>] generic_file_write_iter+0x2e0/0x610 mm/filemap.c:2893
 [<ffffffff8156ef20>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff8156ef20>] __vfs_write+0x3e0/0x580 fs/read_write.c:509
 [<ffffffff81572d17>] vfs_write+0x187/0x530 fs/read_write.c:557
 [<ffffffff81576b49>] SYSC_write fs/read_write.c:604 [inline]
 [<ffffffff81576b49>] SyS_write+0xd9/0x1c0 fs/read_write.c:596
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9b13>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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c