b_state=0x00000029, b_size=512
device loop6 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop6 blocksize: 4096
INFO: task syz-executor6:30278 blocked for more than 140 seconds.
      Not tainted 4.9.112-g9e79039 #7
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor6   D29560 30278  11904 0x00000004
 ffff8801cec34800 ffff8801cf9db480 ffff8801cf9db480 ffff8801b58d1800
 ffff8801db221c18 ffff8801cd9e7ab8 ffffffff839e907d ffffffff81235667
 0000000000000000 ffff8801cec350c0 0000000600000007 ffff8801db2224e8
Call Trace:
 [<ffffffff839ea67f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f5cb8>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f5cb8>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee7527>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff8122c290>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff8122c290>] down_write_nested+0x60/0xa0 kernel/locking/rwsem.c:174
 [<ffffffff815aa01a>] inode_lock_nested include/linux/fs.h:801 [inline]
 [<ffffffff815aa01a>] filename_create+0x17a/0x490 fs/namei.c:3639
 [<ffffffff815ac14d>] user_path_create fs/namei.c:3697 [inline]
 [<ffffffff815ac14d>] SYSC_mknodat fs/namei.c:3764 [inline]
 [<ffffffff815ac14d>] SyS_mknodat fs/namei.c:3752 [inline]
 [<ffffffff815ac14d>] SYSC_mknod fs/namei.c:3798 [inline]
 [<ffffffff815ac14d>] SyS_mknod+0x18d/0x420 fs/namei.c:3796
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9f53>] 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: [<ffffffff8136675c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136675c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.?..}, at: [<ffffffff81425de7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by rs:main Q:Reg/3672:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d818c>] __fdget_pos+0xac/0xd0 fs/file.c:781
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff81572cce>] file_start_write include/linux/fs.h:2640 [inline]
 #1:  (sb_writers#3){.+.+.+}, at: [<ffffffff81572cce>] vfs_write+0x3ae/0x530 fs/read_write.c:556
2 locks held by getty/3770:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f8122>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211edc2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor6/30278:
 #0:  (sb_writers#14){.+.+.+}, at: [<ffffffff815e0a2f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#14){.+.+.+}, at: [<ffffffff815e0a2f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#17/1){+.+.+.}, at: [<ffffffff815aa01a>] inode_lock_nested include/linux/fs.h:801 [inline]
 #1:  (&sb->s_type->i_mutex_key#17/1){+.+.+.}, at: [<ffffffff815aa01a>] filename_create+0x17a/0x490 fs/namei.c:3639
1 lock held by syz-executor6/30281:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d818c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by syz-executor6/30283:
 #0:  (sb_writers#14){.+.+.+}, at: [<ffffffff815e0a2f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#14){.+.+.+}, at: [<ffffffff815e0a2f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#17){++++++}, at: [<ffffffff815a4df5>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#17){++++++}, at: [<ffffffff815a4df5>] do_last fs/namei.c:3312 [inline]
 #1:  (&sb->s_type->i_mutex_key#17){++++++}, at: [<ffffffff815a4df5>] path_openat+0xed5/0x3590 fs/namei.c:3534
1 lock held by syz-executor6/30285:
 #0:  (&sb->s_type->i_mutex_key#17){++++++}, at: [<ffffffff81594cb1>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&sb->s_type->i_mutex_key#17){++++++}, at: [<ffffffff81594cb1>] lookup_slow+0x141/0x470 fs/namei.c:1645
2 locks held by syz-executor6/30288:
 #0:  (sb_writers#14){.+.+.+}, at: [<ffffffff815e0a2f>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#14){.+.+.+}, at: [<ffffffff815e0a2f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#17/1){+.+.+.}, at: [<ffffffff815aa01a>] inode_lock_nested include/linux/fs.h:801 [inline]
 #1:  (&sb->s_type->i_mutex_key#17/1){+.+.+.}, at: [<ffffffff815aa01a>] filename_create+0x17a/0x490 fs/namei.c:3639
1 lock held by init/30290:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/30291:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/30292:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/30293:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/30294:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125
1 lock held by init/30295:
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open_by_driver drivers/tty/tty_io.c:2047 [inline]
 #0:  (tty_mutex){+.+.+.}, at: [<ffffffff821191cc>] tty_open+0x46c/0xe20 drivers/tty/tty_io.c:2125

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

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.112-g9e79039 #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d9217d08 ffffffff81eb3249 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9bd0 ffff8801d9217d40
 ffffffff81ebe547 0000000000000001 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81eb3249>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3249>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebe547>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebe4da>] 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
 [<ffffffff81366cf4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366cf4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366cf4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366cf4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d0bd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fa11c>] 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: 11491 Comm: kpktgend_0 Not tainted 4.9.112-g9e79039 #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88019e33c800 task.stack: ffff8801cf3b8000
RIP: 0010:[<ffffffff81236234>] 
c [<ffffffff81236234>] __lock_acquire+0x64/0x4070 kernel/locking/lockdep.c:3204
RSP: 0018:ffff8801cf3bf6d0  EFLAGS: 00000806
RAX: 1ffff10039e77eee RBX: 0000000000000046 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffffffff85c07fe0
RBP: ffff8801cf3bf880 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88019e33c800
R13: 0000000000000000 R14: ffffffff85c07fe0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fca940e6000 CR3: 00000001c0a25000 CR4: 00000000001606f0
DR0: 0000000020000040 DR1: 0000000020000000 DR2: 00000000200000c0
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffff88019e33d0c0
c 0000000000000046
c ffff88019e33c800
c ffffffff846def20
c
 ffff8801db221d68
c 0000000000000001
c ffff8801cf3bf728
c 0000000000000046
c
 0000000000000003
c ffff8801db221c00
c 0000000000000000
c ffff8801cf3bf740
c
Call Trace:
 [<ffffffff8123acb0>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff839f9e9e>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:112 [inline]
 [<ffffffff839f9e9e>] _raw_spin_lock_irqsave+0x4e/0x62 kernel/locking/spinlock.c:159
 [<ffffffff81f1d43c>] debug_object_assert_init+0xec/0x380 lib/debugobjects.c:611
 [<ffffffff81299910>] debug_timer_assert_init kernel/time/timer.c:737 [inline]
 [<ffffffff81299910>] debug_assert_init kernel/time/timer.c:785 [inline]
 [<ffffffff81299910>] try_to_del_timer_sync+0x70/0x140 kernel/time/timer.c:1214
 [<ffffffff81299ad8>] del_timer_sync+0xf8/0x140 kernel/time/timer.c:1285
 [<ffffffff839f66c3>] schedule_timeout+0x493/0xf70 kernel/time/timer.c:1792
 [<ffffffff830fdaa2>] pktgen_thread_worker+0x5512/0x6880 net/core/pktgen.c:3562
 [<ffffffff8119d0bd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fa11c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Code: 
cc7 
c84 
c24 
ca8 
c00 
c00 
c00 
cc0 
c36 
c3c 
c84 
c48 
cc7 
c84 
c24 
cb0 
c00 
c00 
c00 
cd0 
c61 
c23 
c81 
c48 
c89 
c84 
c24 
c98 
c00 
c00 
c00 
c48 
c8d 
c84 
c24 
ca0 
c00 
c00 
c00 
c48 
cc1 
ce8 
c03 
c<48> 
c89 
c84 
c24 
c90 
c00 
c00 
c00 
c48 
c01 
cd0 
cc7 
c00 
cf1 
cf1 
cf1 
cf1 
cc7 
c40 
c04 
c00 
c
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop6 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop6 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop6 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop6 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop6 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop6 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop6 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop6 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8
b_state=0x00000029, b_size=512
device loop6 blocksize: 4096
__find_get_block_slow() failed. block=1, b_blocknr=8