INFO: task syz-executor0:25394 blocked for more than 140 seconds.
      Not tainted 4.9.117-g8b21e85 #19
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D29624 25394  22356 0x00000004
 ffff8801c0c60000 ffff8801c382b480 ffff8801c382b480 ffff8801995f3000
 ffff8801db321c18 ffff8801d577f808 ffffffff839ebd0d ffffffff81235687
 0000000000000000 ffff8801c0c608c0 0000000600000007 ffff8801db3224e8
Call Trace:
 [<ffffffff839ed30f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839f8948>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f8948>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee8ec7>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839f671c>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839f671c>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff815a51a5>] inode_lock include/linux/fs.h:766 [inline]
 [<ffffffff815a51a5>] do_last fs/namei.c:3312 [inline]
 [<ffffffff815a51a5>] path_openat+0xed5/0x3590 fs/namei.c:3534
 [<ffffffff815abb27>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8156e2fd>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff8156e657>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff8156e657>] SyS_open fs/open.c:1085 [inline]
 [<ffffffff8156e657>] SYSC_creat fs/open.c:1110 [inline]
 [<ffffffff8156e657>] SyS_creat+0x27/0x30 fs/open.c:1108
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fcc13>] 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: [<ffffffff813667fc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813667fc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81426017>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3776:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839fadb2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff821207f2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor0/25394:
 #0:  (sb_writers#14){.+.+.+}, at: [<ffffffff815e0e3f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#14){.+.+.+}, at: [<ffffffff815e0e3f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815a51a5>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815a51a5>] do_last fs/namei.c:3312 [inline]
 #1:  (&sb->s_type->i_mutex_key#18){++++++}, at: [<ffffffff815a51a5>] path_openat+0xed5/0x3590 fs/namei.c:3534

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.117-g8b21e85 #19
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8437d08 ffffffff81eb4be9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9bd0 ffff8801d8437d40
 ffffffff81ebfee7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb4be9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb4be9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebfee7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebfe7a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9cd4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366d94>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366d94>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366d94>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366d94>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d0ed>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fcddc>] 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: 25392 Comm: syz-executor0 Not tainted 4.9.117-g8b21e85 #19
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801995f3000 task.stack: ffff8801c1ee8000
RIP: 0010:[<ffffffff8162479e>] 
c [<ffffffff8162479e>] lookup_bh_lru fs/buffer.c:1329 [inline]
RIP: 0010:[<ffffffff8162479e>] 
c [<ffffffff8162479e>] __find_get_block+0x9e/0x4c0 fs/buffer.c:1356
RSP: 0018:ffff8801c1eef278  EFLAGS: 00000046
RAX: 0000000000040000 RBX: 0000000000000002 RCX: ffffc90005312000
RDX: 1ffff1003ac2726c RSI: ffffffff8162478e RDI: ffff8801d6139360
RBP: ffff8801c1eef2b8 R08: ffff8801995f3960 R09: 0000000000000001
R10: 0000000000000000 R11: 1ffff100332be727 R12: ffff8801d6139348
R13: dffffc0000000000 R14: ffff8801d6139348 R15: 0000000000000002
FS:  00007f406b30f700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f095362e000 CR3: 00000001ac745000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 00000200070cf840
c 0000000000000041
c ffff8801d61c61c0
c 0000000000000001
c
 ffffea00070cf85c
c ffffea00070cf840
c 0000000000000200
c dffffc0000000000
c
 ffff8801c1eef358
c ffffffff81625749
c ffff8801c1eef328
c ffff8801d61c61c8
c
Call Trace:
 [<ffffffff81625749>] __getblk_slow fs/buffer.c:1101 [inline]
 [<ffffffff81625749>] __getblk_gfp+0x189/0x710 fs/buffer.c:1386
 [<ffffffff816290ed>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff818b7908>] sb_bread include/linux/buffer_head.h:300 [inline]
 [<ffffffff818b7908>] fat__get_entry+0x4c8/0x8f0 fs/fat/dir.c:100
 [<ffffffff818bf707>] fat_get_entry fs/fat/dir.c:128 [inline]
 [<ffffffff818bf707>] fat_search_long+0x277/0x1180 fs/fat/dir.c:477
 [<ffffffff818d9c74>] vfat_find+0x134/0x180 fs/fat/namei_vfat.c:708
 [<ffffffff818da451>] vfat_lookup+0xe1/0x530 fs/fat/namei_vfat.c:731
 [<ffffffff8159b55d>] lookup_open+0x63d/0x1930 fs/namei.c:3203
 [<ffffffff815a51c8>] do_last fs/namei.c:3315 [inline]
 [<ffffffff815a51c8>] path_openat+0xef8/0x3590 fs/namei.c:3534
 [<ffffffff815abb27>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8156e2fd>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff8156e657>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff8156e657>] SyS_open fs/open.c:1085 [inline]
 [<ffffffff8156e657>] SYSC_creat fs/open.c:1110 [inline]
 [<ffffffff8156e657>] SyS_creat+0x27/0x30 fs/open.c:1108
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fcc13>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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c<0f> 
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c