INFO: task syz-executor2:15761 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-executor2   D28656 15761  10350 0x00000004
 ffff8801d96f8000 ffff8801a483cfc0 ffff8801a483cfc0 ffff880198f63000
 ffff8801db221c18 ffff88018ad97ab8 ffffffff839f0afd ffffffff81237da7
 0000000000000000 ffff8801d96f88c0 0000000600000007 ffff8801db2224e8
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
 [<ffffffff8122e530>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff8122e530>] down_write_nested+0x60/0xa0 kernel/locking/rwsem.c:174
 [<ffffffff815ae7aa>] inode_lock_nested include/linux/fs.h:801 [inline]
 [<ffffffff815ae7aa>] filename_create+0x17a/0x490 fs/namei.c:3639
 [<ffffffff815b11d6>] user_path_create fs/namei.c:3697 [inline]
 [<ffffffff815b11d6>] SYSC_symlinkat fs/namei.c:4171 [inline]
 [<ffffffff815b11d6>] SyS_symlinkat+0xe6/0x260 fs/namei.c:4158
 [<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/3774:
 #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-executor2/15743:
 #0:  (sb_writers#21){.+.+.+}, at: [<ffffffff815e50cf>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#21){.+.+.+}, at: [<ffffffff815e50cf>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#24/1){+.+.+.}, at: [<ffffffff815ae7aa>] inode_lock_nested include/linux/fs.h:801 [inline]
 #1:  (&sb->s_type->i_mutex_key#24/1){+.+.+.}, at: [<ffffffff815ae7aa>] filename_create+0x17a/0x490 fs/namei.c:3639
2 locks held by syz-executor2/15761:
 #0:  (sb_writers#21){.+.+.+}, at: [<ffffffff815e50cf>] sb_start_write include/linux/fs.h:1573 [inline]
 #0:  (sb_writers#21){.+.+.+}, at: [<ffffffff815e50cf>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#24/1){+.+.+.}, at: [<ffffffff815ae7aa>] inode_lock_nested include/linux/fs.h:801 [inline]
 #1:  (&sb->s_type->i_mutex_key#24/1){+.+.+.}, at: [<ffffffff815ae7aa>] filename_create+0x17a/0x490 fs/namei.c:3639
1 lock held by syz-executor2/15792:
 #0:  (&sb->s_type->i_mutex_key#24){++++++}, at: [<ffffffff815e5ffc>] inode_lock include/linux/fs.h:766 [inline]
 #0:  (&sb->s_type->i_mutex_key#24){++++++}, at: [<ffffffff815e5ffc>] lock_mount+0x8c/0x2c0 fs/namespace.c:2101

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

NMI backtrace for cpu 1
CPU: 1 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
 ffff8801d866fd08 ffffffff81eb95e9 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9fa0 ffff8801d866fd40
 ffffffff81ec4927 0000000000000001 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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.124-g09eb2ba #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84629800 task.stack: ffffffff84600000
RIP: 0010:[<ffffffff81238b61>] 
c [<ffffffff81238b61>] separate_irq_context kernel/locking/lockdep.c:2988 [inline]
RIP: 0010:[<ffffffff81238b61>] 
c [<ffffffff81238b61>] __lock_acquire+0x7b1/0x4070 kernel/locking/lockdep.c:3336
RSP: 0018:ffff8801db207d10  EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffffffff8462a0c8 RCX: 0000000000000000
RDX: 1ffffffff08c5418 RSI: ffffffff8462a0c8 RDI: ffffffff8558fa30
RBP: ffff8801db207eb8 R08: ffffffff8462a0e8 R09: 0000000000000001
R10: ffffffff84629800 R11: 0000000000000001 R12: 000000000000002d
R13: 0000000000000000 R14: 000000000000002d R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbe10d68140 CR3: 00000001ca058000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Stack:
 00000000000001f9
c 000000000000000b
c ffff8801db2185d8
c 0000000c00000008
c
 0000000b00000020
c ffff8801db207d78
c ffffffff81f2106b
c ffffffff8462a0c0
c
 ffffffff8462a0c8
c 0000000000000246
c ffffffff8558fa00
c ffffffff8120a0e2
c
Call Trace:
 [<ffffffff8123ce90>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff812b953a>] seqcount_lockdep_reader_access include/linux/seqlock.h:80 [inline]
 [<ffffffff812b953a>] read_seqcount_begin include/linux/seqlock.h:163 [inline]
 [<ffffffff812b953a>] ktime_get+0x11a/0x1e0 kernel/time/timekeeping.c:757
 [<ffffffff812d0b8c>] tick_nohz_irq_enter kernel/time/tick-sched.c:1144 [inline]
 [<ffffffff812d0b8c>] tick_irq_enter+0xcc/0x220 kernel/time/tick-sched.c:1165
 [<ffffffff8114d423>] irq_enter+0xb3/0xd0 kernel/softirq.c:349
 [<ffffffff83a060fa>] smp_reschedule_interrupt+0xa/0x90 arch/x86/kernel/smp.c:267
 [<ffffffff83a03cd0>] reschedule_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:671
 <EOI> 
d [<ffffffff83a00606>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:55
 [<ffffffff839ffc45>] arch_safe_halt arch/x86/include/asm/paravirt.h:104 [inline]
 [<ffffffff839ffc45>] default_idle+0x55/0x360 arch/x86/kernel/process.c:437
 [<ffffffff8106ae20>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:428
 [<ffffffff83a00a65>] default_idle_call+0x45/0x60 kernel/sched/idle.c:97
 [<ffffffff81225495>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff81225495>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff81225495>] cpu_startup_entry+0x2b5/0x380 kernel/sched/idle.c:303
 [<ffffffff839ed8cc>] rest_init+0x183/0x189 init/main.c:409
 [<ffffffff84c98943>] start_kernel+0x67e/0x6b2 init/main.c:664
 [<ffffffff84c9729a>] x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:196
 [<ffffffff84c973db>] x86_64_start_kernel+0x13f/0x162 arch/x86/kernel/head64.c:177
Code: 
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c<41> 
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c