INFO: task syz-executor.1:21541 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.1  D29608 21541  21538 0x20020000
 ffff8801c510df00 0000000000000000 ffff8801d1b68000 ffff880194eec740
 ffff8801db621018 ffff8801c50dfb50 ffffffff828075c2 ffff880100000001
 ffffffff00000000 fffffbfff08489a8 0007171d00000001 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 kworker/0:1/23:
 #0:  ("events"){.+.+.+}, at: [<ffffffff81130f0c>] process_one_work+0x73c/0x15f0 kernel/workqueue.c:2085
 #1:  ((&rew.rew_work)){+.+...}, at: [<ffffffff81130f44>] process_one_work+0x774/0x15f0 kernel/workqueue.c:2089
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
3 locks held by kworker/0:2/351:
 #0:  ("events"){.+.+.+}, at: [<ffffffff81130f0c>] process_one_work+0x73c/0x15f0 kernel/workqueue.c:2085
 #1:  ((linkwatch_work).work){+.+...}, at: [<ffffffff81130f44>] process_one_work+0x774/0x15f0 kernel/workqueue.c:2089
 #2:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by rsyslogd/1901:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff8156cc7c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/2028:
 #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.5/2091:
 #0:  (tasklist_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.1/21538:
 #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.1/21541:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
3 locks held by kworker/1:0/24895:
 #0:  ("%s"("ipv6_addrconf")){.+.+..}, at: [<ffffffff81130f0c>] process_one_work+0x73c/0x15f0 kernel/workqueue.c:2085
 #1:  ((&(&ifa->dad_work)->work)){+.+...}, at: [<ffffffff81130f44>] process_one_work+0x774/0x15f0 kernel/workqueue.c:2089
 #2:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by syz-executor.3/28877:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
2 locks held by syz-executor.5/28886:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 #1:  (rcu_preempt_state.exp_mutex){+.+...}, at: [<ffffffff8124a749>] exp_funnel_lock kernel/rcu/tree_exp.h:256 [inline]
 #1:  (rcu_preempt_state.exp_mutex){+.+...}, at: [<ffffffff8124a749>] _synchronize_rcu_expedited+0x339/0x840 kernel/rcu/tree_exp.h:569
1 lock held by syz-executor.0/28916:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff8156cc7c>] __fdget_pos+0xac/0xd0 fs/file.c:781
1 lock held by syz-executor.1/28912:
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff81469eb8>] vm_mmap_pgoff+0x128/0x1b0 mm/util.c:327

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

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #23
 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810983b0 ffff8801d9907d40
 ffffffff81b4df89 0000000000000000 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 28940 Comm: syz-executor.4 Not tainted 4.9.141+ #23
task: ffff8801ab090000 task.stack: ffff8801c6460000
RIP: 0010:[<ffffffff81243c41>] 
c [<ffffffff81243c41>] debug_lockdep_rcu_enabled+0x31/0x90 kernel/rcu/update.c:264
RSP: 0018:ffff8801c6467c80  EFLAGS: 00000246
RAX: 0000000000000007 RBX: ffff8801ab090000 RCX: 1ffff10035612115
RDX: 0000000000000000 RSI: 00000000000002dd RDI: ffffffff833e7adc
RBP: ffff8801c6467c80 R08: ffffed0038c8cfb7 R09: ffffed0038c8cfaf
R10: ffffed0038c8cfb6 R11: ffff8801c6467db7 R12: 0000000000000000
R13: ffffffff82b91060 R14: 00000000000002dd R15: 000000007fffffff
FS:  0000000000000000(0000) GS:ffff8801db700000(0063) knlGS:00000000f558db40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f54c6db0 CR3: 00000001a8b9b000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801c6467cb8
c ffffffff811679c1
c ffff8801ab090000
c ffffffff82b91060
c
 00000000000002dd
c 0000000000000000
c 000000007fffffff
c ffff8801c6467cf8
c
 ffffffff81167c85
c 0000000000000286
c ffffffff83248ea8
c ffff8801ab090000
c
Call Trace:
 [<ffffffff811679c1>] ___might_sleep+0x31/0x260 kernel/sched/core.c:7954
 [<ffffffff81167c85>] __might_sleep+0x95/0x1a0 kernel/sched/core.c:7945
 [<ffffffff8149502f>] __might_fault+0xaf/0x1d0 mm/memory.c:4020
 [<ffffffff81d873b5>] copy_to_user arch/x86/include/asm/uaccess.h:733 [inline]
 [<ffffffff81d873b5>] extract_crng_user drivers/char/random.c:1014 [inline]
 [<ffffffff81d873b5>] urandom_read+0x1d5/0x580 drivers/char/random.c:1805
 [<ffffffff81d8824d>] SYSC_getrandom drivers/char/random.c:1965 [inline]
 [<ffffffff81d8824d>] SyS_getrandom+0xcd/0x280 drivers/char/random.c:1946
 [<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: 
c83 
c55 
c48 
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c00 
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cff 
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c48 
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c48 
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c48 
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c03 
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cb6 
c14 
c02 
c48 
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cf8 
c83 
ce0 
c07 
c83 
cc0 
c03 
c38 
cd0 
c7c 
c04 
c84 
cd2 
c75 
c4c 
c<8b> 
c15 
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c1a 
c02 
c85 
cd2 
c74 
c3e 
c48 
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cc7 
c00 
c25 
c1f 
c83 
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cb8 
c00 
c00 
c