IPVS: Creating netns size=2536 id=224
INFO: task syz-executor2:17191 blocked for more than 120 seconds.
      Not tainted 4.9.100-g73fdfa3 #26
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D28552 17191   3823 0x00000002
 ffff8801cf694800 0000000000000000 ffff88019a522f40 ffff8801d86cb000
 ffff8801db321b98 ffff88018d6a7568 ffffffff839e373d ffffffff81233817
 0000000000000000 ffff8801cf6950c0 0000000600000007 ffff8801db322468
Call Trace:
 [<ffffffff839e4d3f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f0378>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f0378>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee51e7>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839ee14c>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839ee14c>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff8211a981>] n_tty_flush_buffer+0x21/0x310 drivers/tty/n_tty.c:359
 [<ffffffff82128b29>] tty_ldisc_hangup+0x89/0x5b0 drivers/tty/tty_ldisc.c:658
 [<ffffffff8210ffb7>] __tty_hangup.part.22+0x5f7/0xb00 drivers/tty/tty_io.c:744
 [<ffffffff821104e1>] __tty_hangup drivers/tty/tty_io.c:694 [inline]
 [<ffffffff821104e1>] tty_vhangup+0x21/0x30 drivers/tty/tty_io.c:817
 [<ffffffff821303c4>] pty_close+0x374/0x4d0 drivers/tty/pty.c:74
 [<ffffffff821120f0>] tty_release+0x370/0xd00 drivers/tty/tty_io.c:1813
 [<ffffffff81575a33>] __fput+0x263/0x700 fs/file_table.c:208
 [<ffffffff81575f55>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8119603c>] task_work_run+0x10c/0x180 kernel/task_work.c:116
 [<ffffffff8113ec91>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff8113ec91>] do_exit+0x9e1/0x27c0 kernel/exit.c:837
 [<ffffffff81144d91>] do_group_exit+0x111/0x340 kernel/exit.c:941
 [<ffffffff81167b8f>] get_signal+0x4cf/0x1450 kernel/signal.c:2317
 [<ffffffff810524d7>] do_signal+0x87/0x19f0 arch/x86/kernel/signal.c:807
 [<ffffffff81005581>] exit_to_usermode_loop+0xe1/0x120 arch/x86/entry/common.c:157
 [<ffffffff810064d4>] prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline]
 [<ffffffff810064d4>] syscall_return_slowpath arch/x86/entry/common.c:260 [inline]
 [<ffffffff810064d4>] do_syscall_64+0x364/0x490 arch/x86/entry/common.c:287
 [<ffffffff839f4613>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
4 locks held by kworker/u4:1/22:
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad3e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad3e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad3e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("%s""netns"){.+.+.+}, at: [<ffffffff8118ad3e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  (net_cleanup_work){+.+.+.}, at: [<ffffffff8118ad78>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (net_mutex){+.+.+.}, at: [<ffffffff8305896f>] cleanup_net+0x13f/0x630 net/core/net_namespace.c:439
 #3:  (rcu_preempt_state.exp_mutex){+.+...}, at: [<ffffffff81280b09>] exp_funnel_lock kernel/rcu/tree_exp.h:256 [inline]
 #3:  (rcu_preempt_state.exp_mutex){+.+...}, at: [<ffffffff81280b09>] _synchronize_rcu_expedited+0x339/0x840 kernel/rcu/tree_exp.h:569
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646ec>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646ec>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81423c00>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
1 lock held by rsyslogd/3615:
 #0:  (&f->f_pos_lock){+.+.+.}, at: [<ffffffff815d56bc>] __fdget_pos+0xac/0xd0 fs/file.c:781
2 locks held by getty/3711:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f27e2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211cc32>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
2 locks held by kworker/1:2/3993:
 #0:  ("events"){.+.+.+}, at: [<ffffffff8118ad3e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("events"){.+.+.+}, at: [<ffffffff8118ad3e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("events"){.+.+.+}, at: [<ffffffff8118ad3e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("events"){.+.+.+}, at: [<ffffffff8118ad3e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&rew.rew_work)){+.+...}, at: [<ffffffff8118ad78>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
4 locks held by syz-executor2/17191:
 #0:  (&tty->legacy_mutex){+.+.+.}, at: [<ffffffff8212d58a>] tty_lock+0x6a/0xd0 drivers/tty/tty_mutex.c:18
 #1:  (&tty->legacy_mutex/1){+.+.+.}, at: [<ffffffff8212d58a>] tty_lock+0x6a/0xd0 drivers/tty/tty_mutex.c:18
 #2:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82127de0>] tty_ldisc_ref+0x20/0x80 drivers/tty/tty_ldisc.c:296
 #3:  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff8211a981>] n_tty_flush_buffer+0x21/0x310 drivers/tty/n_tty.c:359
1 lock held by syz-executor3/21843:
 #0:  (net_mutex){+.+.+.}, at: [<ffffffff83058fb5>] copy_net_ns+0x155/0x290 net/core/net_namespace.c:406

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.100-g73fdfa3 #26
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d853fd08 ffffffff81eb0f09 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b7da0 ffff8801d853fd40
 ffffffff81ebc207 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb0f09>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb0f09>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebc207>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebc19a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b7ea4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81364c84>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81364c84>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81364c84>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81364c84>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ad5d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f47dc>] 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: 128 Comm: kworker/u4:2 Not tainted 4.9.100-g73fdfa3 #26
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
c
task: ffff8801d97bc800 task.stack: ffff8801d96c0000
RIP: 0010:[<ffffffff8135ca0d>] 
c [<ffffffff8135ca0d>] get_current arch/x86/include/asm/current.h:14 [inline]
RIP: 0010:[<ffffffff8135ca0d>] 
c [<ffffffff8135ca0d>] __sanitizer_cov_trace_pc+0xd/0x50 kernel/kcov.c:99
RSP: 0018:ffff8801d96c79c8  EFLAGS: 00000296
RAX: ffff8801d97bc800 RBX: ffffc9000ee1c000 RCX: 0000000000000003
RDX: 0000000000000000 RSI: ffffffff82118ac8 RDI: ffffc9000ee1db1b
RBP: ffff8801d96c79c8 R08: ffff8801d97bd1b0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000533f728bc
R13: 000000000003da58 R14: dffffc0000000000 R15: 0000000533f728bc
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f68599dc000 CR3: 00000001c4269000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d96c7a40
c ffffffff82118adf
c ffffffff82117a5a
c 0000000000000010
c
 ffffc9000ee1e278
c ffffed00379b57e5
c ffff8801bcdabf2c
c ffffc9000ee1c020
c
 0000000000000000
c ffff8801bcdabb80
c ffffc9000ee1e300
c ffffc9000ee1c000
c
Call Trace:
 [<ffffffff82118adf>] echo_buf drivers/tty/n_tty.c:146 [inline]
 [<ffffffff82118adf>] __process_echoes+0x5cf/0x780 drivers/tty/n_tty.c:734
 [<ffffffff82122514>] flush_echoes drivers/tty/n_tty.c:801 [inline]
 [<ffffffff82122514>] __receive_buf drivers/tty/n_tty.c:1617 [inline]
 [<ffffffff82122514>] n_tty_receive_buf_common+0xd34/0x2300 drivers/tty/n_tty.c:1711
 [<ffffffff82123b13>] n_tty_receive_buf2+0x33/0x40 drivers/tty/n_tty.c:1746
 [<ffffffff8212960f>] tty_ldisc_receive_buf+0xaf/0x190 drivers/tty/tty_buffer.c:455
 [<ffffffff8212a613>] receive_buf drivers/tty/tty_buffer.c:474 [inline]
 [<ffffffff8212a613>] flush_to_ldisc+0x253/0x370 drivers/tty/tty_buffer.c:533
 [<ffffffff8118ae31>] process_one_work+0x7e1/0x1500 kernel/workqueue.c:2092
 [<ffffffff8118bc26>] worker_thread+0xd6/0x10a0 kernel/workqueue.c:2226
 [<ffffffff8119ad5d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f47dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Code: 
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c