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WARNING: CPU: 1 PID: 17 at kernel/locking/mutex.c:873 __mutex_trylock_slowpath kernel/locking/mutex.c:873 [inline]
WARNING: CPU: 1 PID: 17 at kernel/locking/mutex.c:873 mutex_trylock+0x2f9/0x3e0 kernel/locking/mutex.c:908
DEBUG_LOCKS_WARN_ON(in_interrupt())[  111.895984] Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 17 Comm: ksoftirqd/1 Not tainted 4.9.124-g09eb2ba #83
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d9abf580 ffffffff81eb95e9 ffffffff83c48ac0 00000000ffffffff
 0000000000000000 0000000000000001 0000000000000369 ffff8801d9abf640
 ffffffff81423eb5 0000000041b58ab3 ffffffff843bb8e8 ffffffff81423cf6
Call Trace:
 [<ffffffff81eb95e9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb95e9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81423eb5>] panic+0x1bf/0x3bc kernel/panic.c:179
 [<ffffffff814241a1>] __warn.cold.9+0xc1/0x17f kernel/panic.c:542
 [<ffffffff81138252>] warn_slowpath_fmt+0xc2/0x100 kernel/panic.c:565
 [<ffffffff839f6af9>] __mutex_trylock_slowpath kernel/locking/mutex.c:873 [inline]
 [<ffffffff839f6af9>] mutex_trylock+0x2f9/0x3e0 kernel/locking/mutex.c:908
 [<ffffffff81284d69>] exp_funnel_lock kernel/rcu/tree_exp.h:256 [inline]
 [<ffffffff81284d69>] _synchronize_rcu_expedited+0x339/0x840 kernel/rcu/tree_exp.h:569
 [<ffffffff812862c3>] synchronize_rcu_expedited kernel/rcu/tree_exp.h:687 [inline]
 [<ffffffff812862c3>] synchronize_rcu.part.62+0xd3/0x110 kernel/rcu/tree_plugin.h:682
 [<ffffffff81286327>] synchronize_rcu+0x27/0x90 kernel/rcu/tree_plugin.h:685
 [<ffffffff836c4baa>] __l2tp_session_unhash+0x38a/0x520 net/l2tp/l2tp_core.c:1796
 [<ffffffff836c4f37>] l2tp_tunnel_closeall+0x1f7/0x350 net/l2tp/l2tp_core.c:1364
 [<ffffffff836c57f2>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1324
 [<ffffffff830281f5>] __sk_destruct+0x55/0x590 net/core/sock.c:1428
 [<ffffffff812899ee>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff812899ee>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff812899ee>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff812899ee>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff812899ee>] rcu_process_callbacks+0x8ae/0x12b0 kernel/rcu/tree.c:3037
 [<ffffffff83a085c0>] __do_softirq+0x210/0x940 kernel/softirq.c:288
 [<ffffffff8114d320>] run_ksoftirqd+0x30/0x60 kernel/softirq.c:680
 [<ffffffff811aa5a9>] smpboot_thread_fn+0x5c9/0x900 kernel/smpboot.c:163
 [<ffffffff8119f3cd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff83a01b9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..