===============================
[ INFO: suspicious RCU usage. ]
4.9.113-g7f6f94c #9 Not tainted
-------------------------------
kernel/rcu/tree_plugin.h:678 Illegal synchronize_rcu() in RCU read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
3 locks held by syz-executor2/3848:
 #0:  (tasklist_lock){.+.+..}, at: [<ffffffff81146692>] do_wait+0x392/0x950 kernel/exit.c:1562
 #1:  (rcu_read_lock){......}, at: [<ffffffff81cf6250>] INIT_LIST_HEAD include/linux/list.h:28 [inline]
 #1:  (rcu_read_lock){......}, at: [<ffffffff81cf6250>] avc_compute_av+0xb0/0x610 security/selinux/avc.c:975
 #2:  (rcu_callback){......}, at: [<ffffffff812878ce>] __rcu_reclaim kernel/rcu/rcu.h:108 [inline]
 #2:  (rcu_callback){......}, at: [<ffffffff812878ce>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 #2:  (rcu_callback){......}, at: [<ffffffff812878ce>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 #2:  (rcu_callback){......}, at: [<ffffffff812878ce>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 #2:  (rcu_callback){......}, at: [<ffffffff812878ce>] rcu_process_callbacks+0x98e/0x12b0 kernel/rcu/tree.c:3037

stack backtrace:
CPU: 0 PID: 3848 Comm: syz-executor2 Not tainted 4.9.113-g7f6f94c #9
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801db207d60 ffffffff81eb32c9 ffff8801d9570000 0000000000000000
 0000000000000002 ffffffff83c6df20 ffff8801c2856dd8 ffff8801db207d90
 ffffffff81426110 ffff8801c2856c80 ffff8801a5f0ee48 ffff8801a5f0e648
Call Trace:
 <IRQ> [  341.350239]  [<ffffffff81eb32c9>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [  341.350239]  [<ffffffff81eb32c9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81426110>] lockdep_rcu_suspicious.cold.48+0x110/0x141 kernel/locking/lockdep.c:4455
 [<ffffffff81284168>] synchronize_rcu+0x68/0x90 kernel/rcu/tree_plugin.h:675
 [<ffffffff836bd17a>] __l2tp_session_unhash+0x38a/0x520 net/l2tp/l2tp_core.c:1796
 [<ffffffff836bd507>] l2tp_tunnel_closeall+0x1f7/0x350 net/l2tp/l2tp_core.c:1364
 [<ffffffff836bddc2>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1324
 [<ffffffff83021095>] __sk_destruct+0x55/0x590 net/core/sock.c:1428
 [<ffffffff812877ee>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff812877ee>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff812877ee>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff812877ee>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff812877ee>] rcu_process_callbacks+0x8ae/0x12b0 kernel/rcu/tree.c:3037
 [<ffffffff83a00b7b>] __do_softirq+0x20b/0x937 kernel/softirq.c:284
 [<ffffffff8114b297>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff8114b297>] irq_exit+0x147/0x190 kernel/softirq.c:405
 [<ffffffff839ff761>] exiting_irq arch/x86/include/asm/apic.h:659 [inline]
 [<ffffffff839ff761>] smp_apic_timer_interrupt+0x81/0xa0 arch/x86/kernel/apic/apic.c:960
 [<ffffffff839fb8f0>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> [  341.463745]  [<ffffffff839f969f>] ? arch_local_irq_restore arch/x86/include/asm/paravirt.h:768 [inline]
 <EOI> [  341.463745]  [<ffffffff839f969f>] ? __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:162 [inline]
 <EOI> [  341.463745]  [<ffffffff839f969f>] ? _raw_spin_unlock_irqrestore+0x5f/0x70 kernel/locking/spinlock.c:191
 [<ffffffff81cf56c9>] spin_unlock_irqrestore include/linux/spinlock.h:362 [inline]
 [<ffffffff81cf56c9>] avc_reclaim_node security/selinux/avc.c:543 [inline]
 [<ffffffff81cf56c9>] avc_alloc_node+0x289/0x3d0 security/selinux/avc.c:561
 [<ffffffff81cf6318>] avc_insert security/selinux/avc.c:672 [inline]
 [<ffffffff81cf6318>] avc_compute_av+0x178/0x610 security/selinux/avc.c:978
 [<ffffffff81cf83f4>] avc_has_perm_noaudit security/selinux/avc.c:1114 [inline]
 [<ffffffff81cf83f4>] avc_has_perm+0x364/0x4f0 security/selinux/avc.c:1148
 [<ffffffff81d0a5ec>] task_has_perm+0x1fc/0x330 security/selinux/hooks.c:1615
 [<ffffffff81d0a743>] selinux_task_wait+0x23/0x30 security/selinux/hooks.c:3954
 [<ffffffff81cf1483>] security_task_wait+0x73/0xb0 security/security.c:1032
 [<ffffffff81142f71>] wait_consider_task+0x2a1/0x3630 kernel/exit.c:1381
 [<ffffffff81146723>] do_wait_thread kernel/exit.c:1494 [inline]
 [<ffffffff81146723>] do_wait+0x423/0x950 kernel/exit.c:1565
 [<ffffffff8114765b>] SYSC_wait4 kernel/exit.c:1697 [inline]
 [<ffffffff8114765b>] SyS_wait4+0x12b/0x1f0 kernel/exit.c:1662
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9f93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
ODEBUG: object ffff8801db207ce8 is NOT on stack ffff8801a6e90000, but annotated
------------[ cut here ]------------
WARNING: CPU: 0 PID: 3848 at lib/debugobjects.c:303 debug_object_is_on_stack lib/debugobjects.c:303 [inline]
WARNING: CPU: 0 PID: 3848 at lib/debugobjects.c:303 __debug_object_init.cold.10+0x6b/0x2b0 lib/debugobjects.c:329