INFO: task syz-executor.3:15625 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.3  D29592 15625  15621 0x00000000
 ffff8801420817c0 ffff8801d091ac00 ffff8800aee26300 ffff88017d0917c0
 ffff8801db721018 ffff8801d12bf840 ffffffff828075c2 ffff8801d9c4e980
 ffffffff83cd4aa0 0000000000000246 0000000000001529 ffff8801db7218f0
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
 [<ffffffff81d28626>] tty_ioctl+0x3b6/0x2190 drivers/tty/tty_io.c:3009
 [<ffffffff81546dec>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff81546dec>] file_ioctl fs/ioctl.c:493 [inline]
 [<ffffffff81546dec>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 [<ffffffff81547e6f>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff81547e6f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<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: [<ffffffff8131c2c0>] rcu_read_unlock include/linux/rcupdate.h:927 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c2c0>] rcu_lock_break kernel/hung_task.c:143 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c2c0>] check_hung_uninterruptible_tasks kernel/hung_task.c:177 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c2c0>] watchdog+0x310/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813fe63f>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/1897:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff8156cc7c>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/2024:
 #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.4/2090:
 #0:  (&rq->lock){-.-.-.}, at: [<ffffffff812692d5>] lock_hrtimer_base.isra.1+0x75/0x130 kernel/time/hrtimer.c:145
2 locks held by kworker/1:0/5677:
 #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
3 locks held by kworker/0:4/8290:
 #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
2 locks held by syz-executor.3/15621:
 #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.3/15625:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82815952>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
2 locks held by syz-executor.0/18506:
 #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
2 locks held by syz-executor.2/18526:
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff8150dd10>] file_start_write include/linux/fs.h:2640 [inline]
 #0:  (sb_writers#4){.+.+.+}, at: [<ffffffff8150dd10>] do_sendfile+0xa80/0xc30 fs/read_write.c:1392
 #1:  (&sb->s_type->i_mutex_key#9){++++++}, at: [<ffffffff8158b831>] inode_lock include/linux/fs.h:766 [inline]
 #1:  (&sb->s_type->i_mutex_key#9){++++++}, at: [<ffffffff8158b831>] __generic_file_fsync+0xc1/0x1a0 fs/libfs.c:978
1 lock held by syz-executor.2/18536:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by syz-executor.3/18530:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
1 lock held by syz-executor.1/18532:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff823412d7>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70

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

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #1
 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810983b0 ffff8801d9907d40
 ffffffff81b4df89 0000000000000000 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 2089 Comm: syz-executor.3 Not tainted 4.9.141+ #1
task: ffff8801d7868000 task.stack: ffff8801aa748000
RIP: 0010:[<ffffffff81243bbf>] 
c [<ffffffff81243bbf>] get_current arch/x86/include/asm/current.h:14 [inline]
RIP: 0010:[<ffffffff81243bbf>] 
c [<ffffffff81243bbf>] debug_lockdep_rcu_enabled.part.0+0xf/0x60 kernel/rcu/update.c:265
RSP: 0018:ffff8801aa74fa18  EFLAGS: 00000202
RAX: dffffc0000000000 RBX: 1ffff100354e9f4e RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff819edb0d RDI: ffffffff831f2500
RBP: ffff8801aa74fa20 R08: ffffed00354e9f55 R09: ffffed00354e9f52
R10: ffffed00354e9f54 R11: 0000000000000003 R12: 0000000000000004
R13: ffff8801aa74fb30 R14: 0000000000000002 R15: 0000000000000000
FS:  0000000000daf940(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff311f85db8 CR3: 00000001aa52e000 CR4: 00000000001606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 1ffff100354e9f4e
c ffff8801aa74fa30
c ffffffff81243c87
c ffff8801aa74fb58
c
 ffffffff819edb12
c ffffffff819eda5e
c ffff8801d78688b0
c 0000000000000003
c
 0000000000000000
c ffff8801aa74fa90
c 000000cf000000cf
c 0000000041b58ab3
c
Call Trace:
 [<ffffffff81243c87>] debug_lockdep_rcu_enabled+0x77/0x90 kernel/rcu/update.c:264
 [<ffffffff819edb12>] rcu_read_unlock include/linux/rcupdate.h:927 [inline]
 [<ffffffff819edb12>] avc_has_perm_noaudit security/selinux/avc.c:1120 [inline]
 [<ffffffff819edb12>] avc_has_perm+0x152/0x3a0 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
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82817893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
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c