INFO: task syz-executor.4:17289 blocked for more than 140 seconds.
      Not tainted 4.9.141+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D28792 17289   2116 0x00000000
 ffff8801a419af80 0000000000000000 ffff8801ad98c200 ffff8801a41997c0
 ffff8801db621018 ffff880195567950 ffffffff828075c2 ffff8801a41a66f8
 ffffffff83ce1a30 ffff880195567b00 0000000000005eb7 ffff8801db6218f0
Call Trace:
 [<ffffffff82808aef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff828142d5>] schedule_timeout+0x735/0xe20 kernel/time/timer.c:1771
 [<ffffffff81d4312c>] down_read_failed drivers/tty/tty_ldsem.c:241 [inline]
 [<ffffffff81d4312c>] __ldsem_down_read_nested+0x33c/0x610 drivers/tty/tty_ldsem.c:332
 [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 [<ffffffff81d3ca85>] tty_ldisc_ref_wait+0x25/0x80 drivers/tty/tty_ldisc.c:275
 [<ffffffff81d221ca>] tty_read+0xfa/0x270 drivers/tty/tty_io.c:1084
 [<ffffffff81507b25>] __vfs_read+0x115/0x560 fs/read_write.c:449
 [<ffffffff8150a7a4>] vfs_read+0x124/0x390 fs/read_write.c:472
 [<ffffffff8150e809>] SYSC_read fs/read_write.c:588 [inline]
 [<ffffffff8150e809>] SyS_read+0xd9/0x1c0 fs/read_write.c:581
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] 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: [<ffffffff8131c0cc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c0cc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813fe63f>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/2031:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor.1/2115:
 #0:  (&rq->lock){-.-.-.}, at: [<ffffffff8280709c>] __schedule+0x13c/0x1b10 kernel/sched/core.c:3448
 #1:  (rcu_read_lock){......}, at: [<ffffffff811fc3cc>] cpuacct_charge+0x7c/0x360 kernel/sched/cpuacct.c:354
2 locks held by syz-executor.4/17266:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d37362>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
1 lock held by syz-executor.4/17289:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
1 lock held by syz-executor.2/17938:
 #0:  (&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff81520d73>] prepare_bprm_creds+0x53/0x110 fs/exec.c:1369
1 lock held by syz-executor.2/17943:
 #0:  (&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff810fec47>] ptrace_attach+0x167/0x590 kernel/ptrace.c:372
1 lock held by syz-executor.2/20196:
 #0:  (&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff81520d73>] prepare_bprm_creds+0x53/0x110 fs/exec.c:1369
1 lock held by syz-executor.2/20197:
 #0:  (&sig->cred_guard_mutex){+.+.+.}, at: [<ffffffff810fec47>] ptrace_attach+0x167/0x590 kernel/ptrace.c:372
1 lock held by syz-executor.3/21989:
 #0:  (sk_lock-AF_PACKET){+.+.+.}, at: [<ffffffff827cd8a3>] lock_sock include/net/sock.h:1404 [inline]
 #0:  (sk_lock-AF_PACKET){+.+.+.}, at: [<ffffffff827cd8a3>] packet_do_bind+0x33/0xb10 net/packet/af_packet.c:3081

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #1
 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810983b0 ffff8801d9907d40
 ffffffff81b4df89 0000000000000001 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81b42e79>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b42e79>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81b4df89>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b4df1c>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff810984b4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131c65d>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131c65d>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131c65d>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131c65d>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff81142c3d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff82817a5c>] 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: 2118 Comm: syz-executor.3 Not tainted 4.9.141+ #1
task: ffff8801c791af80 task.stack: ffff8801ab6c8000
RIP: 0010:[<ffffffff819f7dfc>] 
c [<ffffffff819f7dfc>] task_has_perm+0xcc/0x330 security/selinux/hooks.c:1612
RSP: 0018:ffff8801ab6cfb68  EFLAGS: 00000246
RAX: dffffc0000000000 RBX: 0000000000000004 RCX: ffffed0038f23705
RDX: 1ffff1003b1fb18f RSI: ffffffff819f7de2 RDI: ffff8801d8fd8c78
RBP: ffff8801ab6cfb88 R08: ffff8801c791b830 R09: d8a1064c1ba25689
R10: ffff8801c791af80 R11: 0000000000000001 R12: ffff8801d8fd8c00
R13: ffff8801c791af80 R14: ffff8801ab6cfe4c R15: ffff8801ab6cfe48
FS:  00000000016b3940(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3056637000 CR3: 00000001ab699000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffffffff819f7d30
c ffff880192a4df00
c dffffc0000000000
c ffff880192a4df00
c
 ffff8801ab6cfba0
c ffffffff819f8083
c ffffffff831cc760
c ffff8801ab6cfbd0
c
 ffffffff819e6e73
c 00000000356d9fbb
c 0000000040000005
c 0000000000000000
c
Call Trace:
 [<ffffffff819f8083>] selinux_task_wait+0x23/0x30 security/selinux/hooks.c:3954
 [<ffffffff819e6e73>] security_task_wait+0x73/0xb0 security/security.c:1032
 [<ffffffff810e91f1>] wait_consider_task+0x2a1/0x3620 kernel/exit.c:1377
 [<ffffffff810ec993>] do_wait_thread kernel/exit.c:1490 [inline]
 [<ffffffff810ec993>] do_wait+0x423/0x950 kernel/exit.c:1561
 [<ffffffff810eda0b>] SYSC_wait4 kernel/exit.c:1693 [inline]
 [<ffffffff810eda0b>] SyS_wait4+0x12b/0x1f0 kernel/exit.c:1658
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
c3d 
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c48 
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cc1 
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c80 
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c00 
c<0f> 
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c02 
c00 
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c48 
cb8 
c00 
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c00 
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c64 
c24 
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c