INFO: task syz-executor.4:2540 blocked for more than 140 seconds.
      Not tainted 4.9.141+ #23
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.4  D29608  2540   2529 0x20020000
 ffff8801a84b17c0 0000000000000000 ffff8801cb883700 ffff8801a8bc5f00
 ffff8801db621018 ffff8801a84e7b50 ffffffff828075c2 ffff880100000001
 ffffffff00000000 fffffbfff08489a8 001268a900000001 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
 [<ffffffff81d21dfd>] tty_compat_ioctl+0x12d/0x270 drivers/tty/tty_io.c:3039
 [<ffffffff81619c8d>] C_SYSC_ioctl fs/compat_ioctl.c:1602 [inline]
 [<ffffffff81619c8d>] compat_SyS_ioctl+0x12d/0x1fd0 fs/compat_ioctl.c:1549
 [<ffffffff81006311>] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
 [<ffffffff81006311>] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
 [<ffffffff82818de0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

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/2018:
 #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.4/2529:
 #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
ip6_tunnel: ip6tnl1 xmit: Local address not yet configured!
1 lock held by syz-executor.4/2540:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor.4/2581:
 #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.4/2583:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor.4/7503:
 #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.2/8923:
 #0:  (sk_lock-AF_PACKET){+.+.+.}, at: [<ffffffff827d1f3f>] lock_sock include/net/sock.h:1404 [inline]
 #0:  (sk_lock-AF_PACKET){+.+.+.}, at: [<ffffffff827d1f3f>] packet_setsockopt+0x50f/0x2630 net/packet/af_packet.c:3668

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #23
 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810983b0 ffff8801d9907d40
 ffffffff81b4df89 0000000000000001 0000000000000000 0000000000000003
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: 2072 Comm: syz-executor.0 Not tainted 4.9.141+ #23
task: ffff8801d31a2f80 task.stack: ffff8801ade08000
RIP: 0010:[<ffffffff8120cbd2>] 
c [<ffffffff8120cbd2>] lock_release+0x52/0xc20 kernel/locking/lockdep.c:3768
RSP: 0018:ffff8801ade0f700  EFLAGS: 00000046
RAX: 0000000000000007 RBX: ffffffff84238118 RCX: 0000000000000003
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8801d31a382c
RBP: ffff8801ade0f7a8 R08: ffff8801d31a38c8 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000001 R12: ffffffff84238100
R13: ffff8801d31a2f80 R14: 00000000000000de R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8801db600000(0063) knlGS:0000000009c00900
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 000000002cd37000 CR3: 00000001ae201000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801ade0f710
c ffffffff81243c87
c ffff8801ade0f7c8
c 0000000000000046
c
 0000000000000000
c 0000000000000046
c ffff8801d31a2f80
c 0000000000000000
c
 0000000000000000
c 0000000000000002
c ffff8801ade0f7c8
c ffff8801ade0f798
c
Call Trace:
 [<ffffffff82816f7f>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
 [<ffffffff82816f7f>] _raw_spin_unlock_irqrestore+0x1f/0x70 kernel/locking/spinlock.c:191
 [<ffffffff819eac8c>] spin_unlock_irqrestore include/linux/spinlock.h:362 [inline]
 [<ffffffff819eac8c>] avc_reclaim_node security/selinux/avc.c:541 [inline]
 [<ffffffff819eac8c>] avc_alloc_node+0x31c/0x3c0 security/selinux/avc.c:559
 [<ffffffff819ebf18>] avc_insert security/selinux/avc.c:670 [inline]
 [<ffffffff819ebf18>] avc_compute_av+0x178/0x610 security/selinux/avc.c:976
 [<ffffffff819edd12>] avc_has_perm_noaudit security/selinux/avc.c:1112 [inline]
 [<ffffffff819edd12>] avc_has_perm+0x352/0x3a0 security/selinux/avc.c:1146
 [<ffffffff819f7f2c>] task_has_perm+0x1fc/0x330 security/selinux/hooks.c:1615
 [<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
 [<ffffffff812bf054>] C_SYSC_wait4 kernel/compat.c:543 [inline]
 [<ffffffff812bf054>] compat_SyS_wait4+0x254/0x290 kernel/compat.c:536
 [<ffffffff810c6305>] sys32_waitpid+0x25/0x30 arch/x86/ia32/sys_ia32.c:172
 [<ffffffff81006311>] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline]
 [<ffffffff81006311>] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390
 [<ffffffff82818de0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
Code: 
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c