IPv6: NLM_F_REPLACE set, but no existing node found!
INFO: task syz-executor3:20879 blocked for more than 120 seconds.
      Not tainted 4.9.67-gf26d3c7 #106
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor3   D29312 20879   3532 0x00000004
 ffff8801c9766000 0000000000000000 ffff8801c971c540 ffffffff84426880
 ffff8801db221418 ffff8801c7a07740 ffffffff838981cb ffff8801c7a07718
 ffffffff8123885f 00ffffff838a3b3a ffff8801db221ce8 ffff8801db221d10
Call Trace:
 [<ffffffff8389976f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838a3c50>] rwsem_down_read_failed+0x1e0/0x320 kernel/locking/rwsem-xadd.c:260
 [<ffffffff81dc3878>] call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94
 [<ffffffff838a29d2>] __down_read arch/x86/include/asm/rwsem.h:65 [inline]
 [<ffffffff838a29d2>] down_read+0x52/0xb0 kernel/locking/rwsem.c:24
 [<ffffffff8200a4b5>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592
 [<ffffffff8200b361>] tty_mode_ioctl+0x931/0x9c0 drivers/tty/tty_ioctl.c:970
 [<ffffffff8200b490>] n_tty_ioctl_helper+0x40/0x360 drivers/tty/tty_ioctl.c:1161
 [<ffffffff81fff058>] n_tty_ioctl+0x148/0x2d0 drivers/tty/n_tty.c:2437
 [<ffffffff81ff7e93>] tty_ioctl+0x733/0x2170 drivers/tty/tty_io.c:2992
 [<ffffffff815aa59a>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815aa59a>] do_vfs_ioctl+0x1aa/0x1140 fs/ioctl.c:679
 [<ffffffff815ab5bf>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815ab5bf>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff838a9985>] entry_SYSCALL_64_fastpath+0x23/0xc6

Showing all locks held in the system:
2 locks held by khungtaskd/514:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe05>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136fe05>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.?..}, at: [<ffffffff812355d0>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
2 locks held by getty/3255:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a7b92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82001d24>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
2 locks held by syz-executor3/20879:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838a7b92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&o_tty->termios_rwsem/1){++++.+}, at: [<ffffffff8200a4b5>] set_termios+0xf5/0x670 drivers/tty/tty_ioctl.c:592

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

NMI backtrace for cpu 0
CPU: 0 PID: 514 Comm: khungtaskd Not tainted 4.9.67-gf26d3c7 #106
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8a1fd00 ffffffff81d906e9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810ba170 ffff8801d8a1fd38
 ffffffff81d9b80d 0000000000000000 0000000000000000 ffff8801a9468418
Call Trace:
 [<ffffffff81d906e9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d906e9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9b80d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9b947>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810ba264>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff813703d0>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff813703d0>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff813703d0>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff813703d0>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff811985ad>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838a9c2a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 20863 Comm: syz-executor3 Not tainted 4.9.67-gf26d3c7 #106
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d0759800 task.stack: ffff8801cefe8000
RIP: 0010:[<ffffffff81fff128>] 
c [<ffffffff81fff128>] variable_test_bit arch/x86/include/asm/bitops.h:318 [inline]
RIP: 0010:[<ffffffff81fff128>] 
c [<ffffffff81fff128>] inq_canon drivers/tty/n_tty.c:2411 [inline]
RIP: 0010:[<ffffffff81fff128>] 
c [<ffffffff81fff128>] n_tty_ioctl+0x218/0x2d0 drivers/tty/n_tty.c:2431
RSP: 0018:ffff8801cefefb38  EFLAGS: 00000206
RAX: 0000000000000711 RBX: ffffc900008d6060 RCX: ffffc90001c15000
RDX: 0000000000010000 RSI: 00000000e1115f27 RDI: ffffc900008d7260
RBP: ffff8801cefefb78 R08: 1ffff1003a0eb41a R09: 0000000000000000
R10: 0000000000000003 R11: ffff8801d0759800 R12: ffffc900008d5000
R13: 00000003ce8b7711 R14: 000000002028bffc R15: ffff8801d127dfb8
FS:  00007f8399e82700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7b27efedb8 CR3: 00000001cf96f000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 fffffffffffffffe
c 0000000000000710
c 0000000000000000
c ffff8801d127dd80
c
 1ffff10039dfdf75
c 000000000000541b
c ffffffffffffffe7
c ffff8801a8763800
c
 ffff8801cefefd70
c ffffffff81ff7e93
c ffff8801d0759800
c ffffffff81ffef10
c
Call Trace:
 [<ffffffff81ff7e93>] tty_ioctl+0x733/0x2170 drivers/tty/tty_io.c:2992
 [<ffffffff815aa59a>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815aa59a>] do_vfs_ioctl+0x1aa/0x1140 fs/ioctl.c:679
 [<ffffffff815ab5bf>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815ab5bf>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff838a9985>] entry_SYSCALL_64_fastpath+0x23/0xc6
Code: 
cff 
cff 
ce8 
cbc 
c90 
c36 
cff 
c48 
c8b 
c45 
cd0 
c49 
c8d 
c9c 
c24 
c60 
c10 
c00 
c00 
c4c 
c29 
ce8 
c48 
c89 
c45 
cc0 
ce8 
ca4 
c90 
c36 
cff 
c4c 
c89 
ce8 
c25 
cff 
c0f 
c00 
c00 
c48 
c0f 
ca3 
c03 
c<48> 
c89 
c45 
cc8 
c73 
c43 
ce8 
c8d 
c90 
c36 
cff 
c48 
c8b 
c45 
cc8 
c48 
cbe 
c00 
c00 
c00 
c00 
c