INFO: task syz-executor6:16022 blocked for more than 140 seconds.
      Not tainted 4.9.124-g09eb2ba #31
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor6   D28680 16022   7290 0x00000004
 ffff880197df8000 0000000000000000 ffff8801b82e0fc0 ffff8801d8ff3000
 ffff8801db321c18 ffff8801b780fa38 ffffffff839f0afd ffffffff81237da7
 0000000000000000 ffff880197df88c0 0000000600000007 ffff8801db3224e8
Call Trace:
 [<ffffffff839f20ff>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839fd738>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839fd738>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81eed907>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839fb50c>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839fb50c>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff815e5ffc>] inode_lock include/linux/fs.h:766 [inline]
 [<ffffffff815e5ffc>] lock_mount+0x8c/0x2c0 fs/namespace.c:2101
 [<ffffffff815e8dc7>] do_add_mount+0x27/0x340 fs/namespace.c:2484
 [<ffffffff815eaab2>] do_new_mount fs/namespace.c:2551 [inline]
 [<ffffffff815eaab2>] do_mount+0x1332/0x2740 fs/namespace.c:2859
 [<ffffffff815ec89e>] SYSC_mount fs/namespace.c:3075 [inline]
 [<ffffffff815ec89e>] SyS_mount+0xfe/0x110 fs/namespace.c:3052
 [<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/3761:
 #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
1 lock held by syz-executor6/16022:
 #0:  (&type->i_mutex_dir_key#4){++++++}, at: [<ffffffff815e5ffc>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&type->i_mutex_dir_key#4){++++++}, at: [<ffffffff815e5ffc>] lock_mount+0x8c/0x2c0 fs/namespace.c:2101
1 lock held by syz-executor6/16062:
 #0:  (&type->i_mutex_dir_key#4){++++++}, at: [<ffffffff815a9e8c>] inode_lock_shared include/linux/fs.h:776 [inline]
 #0:  (&type->i_mutex_dir_key#4){++++++}, at: [<ffffffff815a9e8c>] do_last fs/namei.c:3314 [inline]
 #0:  (&type->i_mutex_dir_key#4){++++++}, at: [<ffffffff815a9e8c>] path_openat+0x17dc/0x3590 fs/namei.c:3534

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.124-g09eb2ba #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d863fd08 ffffffff81eb95e9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9fa0 ffff8801d863fd40
 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: 16004 Comm: syz-executor6 Not tainted 4.9.124-g09eb2ba #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801bdc38000 task.stack: ffff880197f48000
RIP: 0010:[<ffffffff81238713>] 
c [<ffffffff81238713>] task_irq_context kernel/locking/lockdep.c:2968 [inline]
RIP: 0010:[<ffffffff81238713>] 
c [<ffffffff81238713>] __lock_acquire+0x363/0x4070 kernel/locking/lockdep.c:3290
RSP: 0018:ffff880197f4f170  EFLAGS: 00000807
RAX: 0000000000000000 RBX: ffff8801bdc388f0 RCX: 0000000000000000
RDX: 1ffff10037b87112 RSI: 000000000000058f RDI: ffff8801bdc38894
RBP: ffff880197f4f320 R08: 0000000000000001 R09: 0000000000000001
R10: ffff8801bdc38000 R11: 1ffff10037b8711d R12: 000000000000058f
R13: 0000000000000001 R14: ffff8801c9e96578 R15: 0000000000000000
FS:  00007fd833b41700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f20468be000 CR3: 00000001cd9ed000 CR4: 00000000001606f0
Stack:
 0000000000000046
c 0000000000000000
c ffff8801bdc388c8
c ffffed0037b87118
c
 ffff8801bdc38000
c dffffc0000000000
c ffff880197f4f1f0
c ffffffff81237da7
c
 0000000000000000
c ffff8801bdc388c0
c ffffffff85620f60
c ffff8801bdc38000
c
Call Trace:
 [<ffffffff8123ce90>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff83a0191e>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:112 [inline]
 [<ffffffff83a0191e>] _raw_spin_lock_irqsave+0x4e/0x62 kernel/locking/spinlock.c:159
 [<ffffffff812238db>] prepare_to_wait_event+0x6b/0x450 kernel/sched/wait.c:213
 [<ffffffff8190c9fe>] request_wait_answer+0x22e/0x6e0 fs/fuse/dev.c:459
 [<ffffffff8190d509>] __fuse_request_send+0x109/0x1b0 fs/fuse/dev.c:480
 [<ffffffff8190d60d>] fuse_request_send+0x5d/0x70 fs/fuse/dev.c:493
 [<ffffffff81917864>] fuse_simple_request+0x2f4/0x660 fs/fuse/dev.c:551
 [<ffffffff8191fc03>] fuse_lookup_name+0x253/0x5d0 fs/fuse/dir.c:369
 [<ffffffff8192006d>] fuse_lookup+0xed/0x3a0 fs/fuse/dir.c:406
 [<ffffffff819204e8>] fuse_atomic_open+0x1c8/0x2e0 fs/fuse/dir.c:545
 [<ffffffff8159ff33>] atomic_open fs/namei.c:3055 [inline]
 [<ffffffff8159ff33>] lookup_open+0xc33/0x1930 fs/namei.c:3194
 [<ffffffff815a9eb3>] do_last fs/namei.c:3315 [inline]
 [<ffffffff815a9eb3>] path_openat+0x1803/0x3590 fs/namei.c:3534
 [<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
Code: 
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c