INFO: task syz-executor.5:22514 blocked for more than 140 seconds.
      Not tainted 4.9.155+ #27
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5  D29480 22514  21827 0x00000004
 ffff8801a5a90000 0000000000000000 ffff8801db721000 ffff8801da6b2f80
 ffff8801db721018 ffff8801982f77b0 ffffffff82806806 dffffc0000000000
 ffff8801982f7788 ffffffff81207081 00ffffff8281194f ffff8801db7218f0
Call Trace:
 [<ffffffff82807d92>] schedule+0x92/0x1c0 kernel/sched/core.c:3553
 [<ffffffff82811bb3>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff82811bb3>] rwsem_down_write_failed+0x3a3/0x750 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81b79027>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff8281095c>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff8281095c>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff81505280>] inode_lock include/linux/fs.h:768 [inline]
 [<ffffffff81505280>] do_truncate2+0x130/0x210 fs/open.c:61
 [<ffffffff8153f28e>] handle_truncate fs/namei.c:3031 [inline]
 [<ffffffff8153f28e>] do_last fs/namei.c:3466 [inline]
 [<ffffffff8153f28e>] path_openat+0x12ae/0x2f60 fs/namei.c:3581
 [<ffffffff81543d21>] do_filp_open+0x1a1/0x280 fs/namei.c:3615
 [<ffffffff815080c0>] do_sys_open+0x2f0/0x610 fs/open.c:1072
 [<ffffffff81508487>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff81508487>] SyS_open fs/open.c:1085 [inline]
 [<ffffffff81508487>] SYSC_creat fs/open.c:1110 [inline]
 [<ffffffff81508487>] SyS_creat+0x27/0x30 fs/open.c:1108
 [<ffffffff810056bd>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<ffffffff82816a93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131bbab>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131bbab>] watchdog+0x11b/0xa40 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813fea8f>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336
2 locks held by getty/2022:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814b83>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d3982e>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
2 locks held by syz-executor.4/18581:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814b83>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d3982e>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
2 locks held by syz-executor.5/22514:
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff81577c8f>] sb_start_write include/linux/fs.h:1575 [inline]
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff81577c8f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:391
 #1:  (&sb->s_type->i_mutex_key#9){+.+.+.}, at: [<ffffffff81505280>] inode_lock include/linux/fs.h:768 [inline]
 #1:  (&sb->s_type->i_mutex_key#9){+.+.+.}, at: [<ffffffff81505280>] do_truncate2+0x130/0x210 fs/open.c:61

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.155+ #27
 ffff8801d9907cd0 ffffffff81b47871 0000000000000001 0000000000000000
 0000000000000001 ffffffff81097301 00000000003fff5d ffff8801d9907d08
 ffffffff81b52afc 0000000000000001 0000000000000000 0000000000000001
Call Trace:
 [<ffffffff81b47871>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b47871>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff81b52afc>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b52a84>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<ffffffff81097494>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131c087>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131c087>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131c087>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131c087>] watchdog+0x5f7/0xa40 kernel/hung_task.c:239
 [<ffffffff81142028>] kthread+0x278/0x310 kernel/kthread.c:211
 [<ffffffff82816c5c>] 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 4.9.155+ #27
task: ffffffff8302d180 task.stack: ffffffff83000000
RIP: 0010:[<ffffffff8124376a>] 
c [<ffffffff8124376a>] debug_lockdep_rcu_enabled.part.0+0x2a/0x60 kernel/rcu/update.c:265
RSP: 0018:ffff8801db607c98  EFLAGS: 00000803
RAX: dffffc0000000000 RBX: ffffffff8302d180 RCX: 1ffffffff063ed60
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8302da2c
RBP: ffff8801db607ca0 R08: 0000000000000000 R09: ffff8801db621100
R10: ffff88021fffd010 R11: 0000012d5b9c9e92 R12: 0000000000000000
R13: ffff8801db6210a0 R14: ffff8801db621170 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c4268b1000 CR3: 00000001d066d000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000955
c ffff8801db607cb0
c ffffffff81243811
c ffff8801db607db0
c
 ffffffff811914cf
c ffffffff81babb7c
c ffffffff81babb7c
c ffffffff831f6b00
c
 0000000000000001
c ffff8801db61c5d0
c ffff8801db61cb00
c dffffc0000000000
c
Call Trace:
 <IRQ> 
d [<ffffffff81243811>] debug_lockdep_rcu_enabled+0x71/0xa0 kernel/rcu/update.c:264
 [<ffffffff811914cf>] trace_sched_contrib_scale_f include/trace/events/sched.h:590 [inline]
 [<ffffffff811914cf>] __update_load_avg kernel/sched/fair.c:2873 [inline]
 [<ffffffff811914cf>] update_cfs_rq_load_avg kernel/sched/fair.c:3291 [inline]
 [<ffffffff811914cf>] update_blocked_averages+0x1e7f/0x4f70 kernel/sched/fair.c:8218
 [<ffffffff811d1264>] rebalance_domains+0xf4/0x960 kernel/sched/fair.c:10092
 [<ffffffff811d1dc0>] run_rebalance_domains+0x2f0/0x500 kernel/sched/fair.c:10349
 [<ffffffff8281be7d>] __do_softirq+0x22d/0x964 kernel/softirq.c:288
 [<ffffffff810eecd9>] invoke_softirq kernel/softirq.c:368 [inline]
 [<ffffffff810eecd9>] irq_exit+0x119/0x160 kernel/softirq.c:409
 [<ffffffff8281994e>] smp_reschedule_interrupt+0x6e/0x90 arch/x86/kernel/smp.c:270
 [<ffffffff828187ad>] reschedule_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:671
 <EOI> 
d [<ffffffff82815692>] ? native_safe_halt+0x2/0x10 arch/x86/include/asm/irqflags.h:56
 [<ffffffff81068160>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:428
 [<ffffffff82815ae6>] default_idle_call+0x36/0x60 kernel/sched/idle.c:97
 [<ffffffff811f1233>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff811f1233>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff811f1233>] cpu_startup_entry+0x283/0x3a0 kernel/sched/idle.c:303
 [<ffffffff82804124>] rest_init+0x18b/0x194 init/main.c:409
 [<ffffffff83420948>] start_kernel+0x619/0x64d init/main.c:664
 [<ffffffff8341f29a>] x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:196
 [<ffffffff8341f3d3>] x86_64_start_kernel+0x137/0x15a arch/x86/kernel/head64.c:177
Code: 
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c