b_state=0x00000029, b_size=512
device loop0 blocksize: 2048
__find_get_block_slow() failed. block=2, b_blocknr=8
b_state=0x00000029, b_size=512
device loop0 blocksize: 2048
INFO: task syz-executor0:1868 blocked for more than 140 seconds.
      Not tainted 4.9.122-g54068d6 #26
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D28648  1868    633 0x00000004
 ffff8801d423c800 0000000000000000 ffff880198810000 ffff8801d55e6000
 ffff8801db321c18 ffff880199367418 ffffffff839efdcd ffffffff812378c7
 0000000000000000 ffff8801d423d0c0 0000000600000007 ffff8801db3224e8
Call Trace:
 [<ffffffff839f13cf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839fca08>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839fca08>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81eecb47>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839fa7dc>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839fa7dc>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff8144001d>] inode_lock include/linux/fs.h:766 [inline]
 [<ffffffff8144001d>] generic_file_write_iter+0x9d/0x610 mm/filemap.c:2903
 [<ffffffff815727a0>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff815727a0>] __vfs_write+0x3e0/0x580 fs/read_write.c:509
 [<ffffffff81574f30>] __kernel_write+0xf0/0x340 fs/read_write.c:529
 [<ffffffff816187ad>] write_pipe_buf+0x15d/0x1f0 fs/splice.c:816
 [<ffffffff816197b6>] splice_from_pipe_feed fs/splice.c:521 [inline]
 [<ffffffff816197b6>] __splice_from_pipe+0x316/0x710 fs/splice.c:645
 [<ffffffff8161bcf9>] splice_from_pipe+0xf9/0x170 fs/splice.c:680
 [<ffffffff8161bdfc>] default_file_splice_write+0x3c/0x80 fs/splice.c:828
 [<ffffffff81616398>] do_splice_from fs/splice.c:870 [inline]
 [<ffffffff81616398>] direct_splice_actor+0x128/0x190 fs/splice.c:1037
 [<ffffffff816176e1>] splice_direct_to_actor+0x2c1/0x7e0 fs/splice.c:992
 [<ffffffff81617da3>] do_splice_direct+0x1a3/0x270 fs/splice.c:1080
 [<ffffffff81579170>] do_sendfile+0x4f0/0xc60 fs/read_write.c:1393
 [<ffffffff8157b1f1>] SYSC_sendfile64 fs/read_write.c:1448 [inline]
 [<ffffffff8157b1f1>] SyS_sendfile64+0xd1/0x160 fs/read_write.c:1440
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff83a00cd3>] 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: [<ffffffff81368a5c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81368a5c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff814282c8>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3682:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815dbb4c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3779:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839fee72>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff82124562>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor0/1868:
 #0:  (sb_writers#11){.+.+.+}, at: [<ffffffff81579598>] file_start_write include/linux/fs.h:2640 [inline]
 #0:  (sb_writers#11){.+.+.+}, at: [<ffffffff81579598>] do_sendfile+0x918/0xc60 fs/read_write.c:1392
 #1:  (&sb->s_type->i_mutex_key#20){++++++}, at: [<ffffffff8144001d>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#20){++++++}, at: [<ffffffff8144001d>] generic_file_write_iter+0x9d/0x610 mm/filemap.c:2903

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

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.122-g54068d6 #26
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d850fd08 ffffffff81eb8829 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9fa0 ffff8801d850fd40
 ffffffff81ec3b67 0000000000000001 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb8829>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb8829>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ec3b67>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ec3afa>] 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
 [<ffffffff81368ff4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81368ff4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81368ff4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81368ff4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119f38d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff83a00e9c>] 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: 1844 Comm: syz-executor0 Not tainted 4.9.122-g54068d6 #26
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d6cd4800 task.stack: ffff88019b300000
RIP: 0010:[<ffffffff8215533b>] 
c [<ffffffff8215533b>] inb arch/x86/include/asm/io.h:316 [inline]
RIP: 0010:[<ffffffff8215533b>] 
c [<ffffffff8215533b>] io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:414
RSP: 0018:ffff88019b306698  EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff821552e1 RDI: ffffffff864ace78
RBP: ffff88019b3066a8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff864ace40
R13: 0000000000000020 R14: fffffbfff0c95a0f R15: fffffbfff0c959d1
FS:  00007f513b05d700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f065df7c000 CR3: 00000001cdf97000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff864ace40
c 000000000000270a
c ffff88019b3066f8
c ffffffff82156f04
c
 ffffffff81ee3b58
c ffffffff864ace88
c ffffffff864ad07a
c ffffffff864ace40
c
 0000000000000061
c ffffffff82157050
c dffffc0000000000
c 0000000000000061
c
Call Trace:
 [<ffffffff82156f04>] serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 [<ffffffff82156f04>] wait_for_xmitr+0x94/0x1e0 drivers/tty/serial/8250/8250_port.c:1998
 [<ffffffff8215706f>] serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3104
 [<ffffffff8213f899>] uart_console_write+0x59/0xf0 drivers/tty/serial/serial_core.c:1859
 [<ffffffff82163288>] serial8250_console_write+0x528/0x820 drivers/tty/serial/8250/8250_port.c:3170
 [<ffffffff8214fdef>] univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:594
 [<ffffffff8125df4d>] call_console_drivers.isra.18.constprop.28+0x1ad/0x360 kernel/printk/printk.c:1589
 [<ffffffff81260d4f>] console_unlock+0x42f/0xb40 kernel/printk/printk.c:2449
 [<ffffffff812618a8>] vprintk_emit+0x448/0x790 kernel/printk/printk.c:1903
 [<ffffffff81261c18>] vprintk+0x28/0x30 kernel/printk/printk.c:1913
 [<ffffffff81261c3d>] vprintk_default+0x1d/0x30 kernel/printk/printk.c:1914
 [<ffffffff8142f09d>] vprintk_func kernel/printk/internal.h:36 [inline]
 [<ffffffff8142f09d>] printk+0xaf/0xd7 kernel/printk/printk.c:1975
 [<ffffffff81cc40b4>] fat_msg+0xdc/0x110 fs/fat/misc.c:54
 [<ffffffff81cc41f1>] __fat_fs_error+0x109/0x208 fs/fat/misc.c:29
 [<ffffffff818ba945>] fat_get_cluster+0xa15/0xbc0 fs/fat/cache.c:263
 [<ffffffff818dafb5>] fat_chain_add+0x395/0x610 fs/fat/misc.c:113
 [<ffffffff818d81af>] fat_add_cluster+0xbf/0xe0 fs/fat/inode.c:105
 [<ffffffff818d84af>] __fat_get_block fs/fat/inode.c:147 [inline]
 [<ffffffff818d84af>] fat_get_block+0x2df/0x800 fs/fat/inode.c:176
 [<ffffffff8162da31>] __block_write_begin_int+0x391/0x1040 fs/buffer.c:1987
 [<ffffffff8162e77f>] __block_write_begin fs/buffer.c:2038 [inline]
 [<ffffffff8162e77f>] block_write_begin+0x5f/0x180 fs/buffer.c:2097
 [<ffffffff8162ed93>] cont_write_begin+0x4f3/0x810 fs/buffer.c:2450
 [<ffffffff818d45ea>] fat_write_begin+0x9a/0x120 fs/fat/inode.c:222
 [<ffffffff81438281>] generic_perform_write+0x301/0x510 mm/filemap.c:2753
 [<ffffffff8143fd92>] __generic_file_write_iter+0x352/0x540 mm/filemap.c:2878
 [<ffffffff81440260>] generic_file_write_iter+0x2e0/0x610 mm/filemap.c:2906
 [<ffffffff815727a0>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff815727a0>] __vfs_write+0x3e0/0x580 fs/read_write.c:509
 [<ffffffff81574f30>] __kernel_write+0xf0/0x340 fs/read_write.c:529
 [<ffffffff816187ad>] write_pipe_buf+0x15d/0x1f0 fs/splice.c:816
 [<ffffffff816197b6>] splice_from_pipe_feed fs/splice.c:521 [inline]
 [<ffffffff816197b6>] __splice_from_pipe+0x316/0x710 fs/splice.c:645
 [<ffffffff8161bcf9>] splice_from_pipe+0xf9/0x170 fs/splice.c:680
 [<ffffffff8161bdfc>] default_file_splice_write+0x3c/0x80 fs/splice.c:828
 [<ffffffff81616398>] do_splice_from fs/splice.c:870 [inline]
 [<ffffffff81616398>] direct_splice_actor+0x128/0x190 fs/splice.c:1037
 [<ffffffff816176e1>] splice_direct_to_actor+0x2c1/0x7e0 fs/splice.c:992
 [<ffffffff81617da3>] do_splice_direct+0x1a3/0x270 fs/splice.c:1080
 [<ffffffff81579170>] do_sendfile+0x4f0/0xc60 fs/read_write.c:1393
 [<ffffffff8157b1f1>] SYSC_sendfile64 fs/read_write.c:1448 [inline]
 [<ffffffff8157b1f1>] SyS_sendfile64+0xd1/0x160 fs/read_write.c:1440
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff83a00cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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