loop0: rw=0, want=18442984958116442982, limit=264192
attempt to access beyond end of device
loop0: rw=0, want=18442984958116442984, limit=264192
attempt to access beyond end of device
loop0: rw=0, want=18442984958116442986, limit=264192
INFO: task syz-executor0:3840 blocked for more than 140 seconds.
      Not tainted 4.9.124-g6a1b592 #30
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D25800  3840      1 0x00000004
 ffff8801c2f58000 0000000000000000 ffff8801c1266a00 ffff8801d9070000
 ffff8801db321c18 ffff8801a3f3f4c8 ffffffff839f0afd ffff8801c2f588c8
 ffffed00385eb118 ffff8801c2f58000 00fffc0000000000 ffff8801db3224e8
Call Trace:
 [<ffffffff839f20ff>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839f2a83>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3586
 [<ffffffff839f6f06>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff839f6f06>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff818df1b1>] vfat_lookup+0xd1/0x530 fs/fat/namei_vfat.c:729
 [<ffffffff8159953e>] lookup_slow+0x23e/0x470 fs/namei.c:1668
 [<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
2 locks held by getty/3744:
 #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
2 locks held by syz-executor0/3840:
 #0:  (&sb->s_type->i_mutex_key#27){++++++}, at: [<ffffffff81599441>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#27){++++++}, at: [<ffffffff81599441>] lookup_slow+0x141/0x470 fs/namei.c:1645
 #1:  (&sbi->s_lock){+.+.+.}, at: [<ffffffff818df1b1>] vfat_lookup+0xd1/0x530 fs/fat/namei_vfat.c:729

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.124-g6a1b592 #30
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d848fd08 ffffffff81eb95e9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9fa0 ffff8801d848fd40
 ffffffff81ec4927 0000000000000000 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 23781 Comm: syz-executor0 Not tainted 4.9.124-g6a1b592 #30
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d3218000 task.stack: ffff8801a6258000
RIP: 0010:[<ffffffff81626013>] 
c [<ffffffff81626013>] constant_test_bit arch/x86/include/asm/bitops.h:311 [inline]
RIP: 0010:[<ffffffff81626013>] 
c [<ffffffff81626013>] buffer_mapped include/linux/buffer_head.h:122 [inline]
RIP: 0010:[<ffffffff81626013>] 
c [<ffffffff81626013>] init_page_buffers+0x1a3/0x350 fs/buffer.c:960
RSP: 0018:ffff8801a625f850  EFLAGS: 00000246
RAX: 0000000000040000 RBX: dffffc0000000000 RCX: ffffc90000ab6000
RDX: 1ffff1003abd34bd RSI: ffffffff81626008 RDI: ffff8801d5e9a3f8
RBP: ffff8801a625f890 R08: ffff8801d3218960 R09: 0000000000000001
R10: 0000000000000000 R11: 1ffff1003a643127 R12: 0000000000000042
R13: ffff8801d5e9a0a8 R14: ffff8801d5d89700 R15: ffff8801d5e9a5e8
FS:  00007f39249de700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c42da49010 CR3: 0000000197a7a000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000008100000
c 0000000000000001
c 0000000000040800
c 0000000000000003
c
 0000000000000200
c ffffea000705a7c0
c 0000000000000200
c dffffc0000000000
c
 ffff8801a625f930
c ffffffff81629ed9
c ffff8801d32188c0
c ffff8801d5d89708
c
Call Trace:
 [<ffffffff81629ed9>] grow_dev_page fs/buffer.c:1014 [inline]
 [<ffffffff81629ed9>] grow_buffers fs/buffer.c:1078 [inline]
 [<ffffffff81629ed9>] __getblk_slow fs/buffer.c:1105 [inline]
 [<ffffffff81629ed9>] __getblk_gfp+0x579/0x710 fs/buffer.c:1386
 [<ffffffff8162d48d>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff818bc678>] sb_bread include/linux/buffer_head.h:300 [inline]
 [<ffffffff818bc678>] fat__get_entry+0x4c8/0x8f0 fs/fat/dir.c:100
 [<ffffffff818c56ec>] fat_get_entry fs/fat/dir.c:128 [inline]
 [<ffffffff818c56ec>] __fat_readdir+0x36c/0x1840 fs/fat/dir.c:589
 [<ffffffff818c6c01>] fat_readdir+0x41/0x50 fs/fat/dir.c:703
 [<ffffffff815b86dc>] iterate_dir+0x1ac/0x600 fs/readdir.c:50
 [<ffffffff815b971c>] SYSC_getdents fs/readdir.c:230 [inline]
 [<ffffffff815b971c>] SyS_getdents+0x13c/0x2a0 fs/readdir.c:211
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff83a019d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
cff 
c48 
c8b 
c45 
cc0 
c89 
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c48 
cd3 
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c48 
c89 
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cd0 
c48 
cbb 
c00 
c00 
c00 
c00 
c00 
cfc 
cff 
cdf 
c4d 
c89 
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cac 
cd3 
cff 
c4c 
c89 
cfa 
c48 
cc1 
cea 
c03 
c80 
c3c 
c1a 
c00 
c<0f> 
c85 
c10 
c01 
c00 
c00 
c49 
c8b 
c17 
c83 
ce2 
c20 
c0f 
c85 
c97 
c00 
c00 
c00 
ce8 
cc6 
cac 
c