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WARNING: CPU: 1 PID: 6407 at kernel/locking/mutex.c:873 __mutex_trylock_slowpath kernel/locking/mutex.c:873 [inline]
WARNING: CPU: 1 PID: 6407 at kernel/locking/mutex.c:873 mutex_trylock+0x2f9/0x3e0 kernel/locking/mutex.c:908
DEBUG_LOCKS_WARN_ON(in_interrupt())[   45.362378] Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 6407 Comm: syz-executor0 Not tainted 4.9.97-g19bd3e3 #15
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801db3077f8 ffffffff81eb0b69 ffffffff83c484a0 00000000ffffffff
 0000000000000000 0000000000000001 0000000000000369 ffff8801db3078b8
 ffffffff8141f975 0000000041b58ab3 ffffffff843b8408 ffffffff8141f7b6
Call Trace:
 <IRQ> [   45.415176]  [<ffffffff81eb0b69>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [   45.415176]  [<ffffffff81eb0b69>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8141f975>] panic+0x1bf/0x3bc kernel/panic.c:179
 [<ffffffff8141fc61>] __warn.cold.9+0xc1/0x17f kernel/panic.c:542
 [<ffffffff811344b2>] warn_slowpath_fmt+0xc2/0x100 kernel/panic.c:565
 [<ffffffff839e9759>] __mutex_trylock_slowpath kernel/locking/mutex.c:873 [inline]
 [<ffffffff839e9759>] mutex_trylock+0x2f9/0x3e0 kernel/locking/mutex.c:908
 [<ffffffff81280b09>] exp_funnel_lock kernel/rcu/tree_exp.h:256 [inline]
 [<ffffffff81280b09>] _synchronize_rcu_expedited+0x339/0x840 kernel/rcu/tree_exp.h:569
 [<ffffffff81282063>] synchronize_rcu_expedited kernel/rcu/tree_exp.h:687 [inline]
 [<ffffffff81282063>] synchronize_rcu.part.62+0xd3/0x110 kernel/rcu/tree_plugin.h:676
 [<ffffffff812820c7>] synchronize_rcu+0x27/0x90 kernel/rcu/tree_plugin.h:679
 [<ffffffff836b7a9a>] __l2tp_session_unhash+0x38a/0x520 net/l2tp/l2tp_core.c:1796
 [<ffffffff836b7e27>] l2tp_tunnel_closeall+0x1f7/0x350 net/l2tp/l2tp_core.c:1364
 [<ffffffff836b86e2>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1324
 [<ffffffff8301d095>] __sk_destruct+0x55/0x590 net/core/sock.c:1428
 [<ffffffff8128578e>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff8128578e>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff8128578e>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff8128578e>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff8128578e>] rcu_process_callbacks+0x8ae/0x12b0 kernel/rcu/tree.c:3037
 [<ffffffff839fb23b>] __do_softirq+0x20b/0x937 kernel/softirq.c:284
 [<ffffffff81149037>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff81149037>] irq_exit+0x147/0x190 kernel/softirq.c:405
 [<ffffffff839f9e21>] exiting_irq arch/x86/include/asm/apic.h:659 [inline]
 [<ffffffff839f9e21>] smp_apic_timer_interrupt+0x81/0xa0 arch/x86/kernel/apic/apic.c:960
 [<ffffffff839f5fb0>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> [   45.677240]  [<ffffffff839f3d5f>] ? arch_local_irq_restore arch/x86/include/asm/paravirt.h:768 [inline]
 <EOI> [   45.677240]  [<ffffffff839f3d5f>] ? __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:162 [inline]
 <EOI> [   45.677240]  [<ffffffff839f3d5f>] ? _raw_spin_unlock_irqrestore+0x5f/0x70 kernel/locking/spinlock.c:191
 [<ffffffff8304a4a1>] spin_unlock_irqrestore include/linux/spinlock.h:362 [inline]
 [<ffffffff8304a4a1>] __skb_try_recv_datagram+0x3d1/0x8d0 net/core/datagram.c:247
 [<ffffffff8304ab25>] __skb_recv_datagram+0x185/0x200 net/core/datagram.c:273
 [<ffffffff835bfa09>] udpv6_recvmsg+0x289/0x19f0 net/ipv6/udp.c:347
 [<ffffffff83424bfe>] inet_recvmsg+0x23e/0x4c0 net/ipv4/af_inet.c:801
 [<ffffffff8300c51c>] sock_recvmsg_nosec+0x8c/0xb0 net/socket.c:737
 [<ffffffff83014df2>] ___sys_recvmsg+0x242/0x550 net/socket.c:2128
 [<ffffffff8301744d>] __sys_recvmmsg+0x25d/0x700 net/socket.c:2236
 [<ffffffff830179db>] SYSC_recvmmsg net/socket.c:2317 [inline]
 [<ffffffff830179db>] SyS_recvmmsg+0xeb/0x1c0 net/socket.c:2301
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f4653>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..