===============================
[ INFO: suspicious RCU usage. ]
4.9.101-gaef17a5 #32 Not tainted
-------------------------------
kernel/rcu/tree_plugin.h:672 Illegal synchronize_rcu() in RCU read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
4 locks held by udevd/2370:
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff8112f5f3>] dup_mmap kernel/fork.c:568 [inline]
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff8112f5f3>] dup_mm kernel/fork.c:1150 [inline]
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff8112f5f3>] copy_mm kernel/fork.c:1204 [inline]
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff8112f5f3>] copy_process.part.51+0x39d3/0x6330 kernel/fork.c:1670
 #1:  (&mm->mmap_sem/1){+.+.+.}, at: [<ffffffff8112f619>] dup_mmap kernel/fork.c:577 [inline]
 #1:  (&mm->mmap_sem/1){+.+.+.}, at: [<ffffffff8112f619>] dup_mm kernel/fork.c:1150 [inline]
 #1:  (&mm->mmap_sem/1){+.+.+.}, at: [<ffffffff8112f619>] copy_mm kernel/fork.c:1204 [inline]
 #1:  (&mm->mmap_sem/1){+.+.+.}, at: [<ffffffff8112f619>] copy_process.part.51+0x39f9/0x6330 kernel/fork.c:1670
 #2:  (rcu_read_lock){......}, at: [<ffffffff81cf5aa3>] avc_has_perm_noaudit+0xa3/0x450 security/selinux/avc.c:1108
 #3:  (rcu_callback){......}, at: [<ffffffff812858ae>] __rcu_reclaim kernel/rcu/rcu.h:108 [inline]
 #3:  (rcu_callback){......}, at: [<ffffffff812858ae>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 #3:  (rcu_callback){......}, at: [<ffffffff812858ae>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 #3:  (rcu_callback){......}, at: [<ffffffff812858ae>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 #3:  (rcu_callback){......}, at: [<ffffffff812858ae>] rcu_process_callbacks+0x98e/0x12b0 kernel/rcu/tree.c:3037

stack backtrace:
CPU: 1 PID: 2370 Comm: udevd Not tainted 4.9.101-gaef17a5 #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801db307d60 ffffffff81eb1009 ffff8801bb3ec800 0000000000000000
 0000000000000002 ffffffff83c6da00 ffff8801d47e3a58 ffff8801db307d90
 ffffffff81423f99 ffff8801d47e3900 ffff8801b5bf9948 ffff8801b5bf9148
Call Trace:
 <IRQ> [  130.438168]  [<ffffffff81eb1009>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [  130.438168]  [<ffffffff81eb1009>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81423f99>] lockdep_rcu_suspicious.cold.48+0x110/0x141 kernel/locking/lockdep.c:4455
 [<ffffffff81282148>] synchronize_rcu+0x68/0x90 kernel/rcu/tree_plugin.h:669
 [<ffffffff836b7cfa>] __l2tp_session_unhash+0x38a/0x520 net/l2tp/l2tp_core.c:1796
 [<ffffffff836b8087>] l2tp_tunnel_closeall+0x1f7/0x350 net/l2tp/l2tp_core.c:1364
 [<ffffffff836b8942>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1324
 [<ffffffff8301d095>] __sk_destruct+0x55/0x590 net/core/sock.c:1428
 [<ffffffff812857ce>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff812857ce>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff812857ce>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff812857ce>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff812857ce>] rcu_process_callbacks+0x8ae/0x12b0 kernel/rcu/tree.c:3037
 [<ffffffff839fb47b>] __do_softirq+0x20b/0x937 kernel/softirq.c:284
 [<ffffffff81149077>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff81149077>] irq_exit+0x147/0x190 kernel/softirq.c:405
 [<ffffffff839fa061>] exiting_irq arch/x86/include/asm/apic.h:659 [inline]
 [<ffffffff839fa061>] smp_apic_timer_interrupt+0x81/0xa0 arch/x86/kernel/apic/apic.c:960
 [<ffffffff839f61f0>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> [  130.551718]  [<ffffffff81238ee3>] ? arch_local_irq_restore arch/x86/include/asm/paravirt.h:768 [inline]
 <EOI> [  130.551718]  [<ffffffff81238ee3>] ? lock_acquire+0x173/0x3e0 kernel/locking/lockdep.c:3759
 [<ffffffff81cf5ad5>] rcu_lock_acquire include/linux/rcupdate.h:493 [inline]
 [<ffffffff81cf5ad5>] rcu_read_lock include/linux/rcupdate.h:875 [inline]
 [<ffffffff81cf5ad5>] avc_has_perm_noaudit+0xd5/0x450 security/selinux/avc.c:1110
 [<ffffffff81d0492a>] cred_has_capability+0x13a/0x2e0 security/selinux/hooks.c:1666
 [<ffffffff81d04b1e>] selinux_vm_enough_memory+0x4e/0x60 security/selinux/hooks.c:2255
 [<ffffffff81ceae37>] security_vm_enough_memory_mm+0x77/0xb0 security/security.c:232
 [<ffffffff8112fae7>] dup_mmap kernel/fork.c:609 [inline]
 [<ffffffff8112fae7>] dup_mm kernel/fork.c:1150 [inline]
 [<ffffffff8112fae7>] copy_mm kernel/fork.c:1204 [inline]
 [<ffffffff8112fae7>] copy_process.part.51+0x3ec7/0x6330 kernel/fork.c:1670
 [<ffffffff811323d0>] copy_process kernel/fork.c:1497 [inline]
 [<ffffffff811323d0>] _do_fork+0x1b0/0xdc0 kernel/fork.c:1955
 [<ffffffff811330b7>] SYSC_clone kernel/fork.c:2065 [inline]
 [<ffffffff811330b7>] SyS_clone+0x37/0x50 kernel/fork.c:2059
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f4893>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
ODEBUG: object ffff8801db307ce8 is NOT on stack ffff8801b98c8000, but annotated
------------[ cut here ]------------
WARNING: CPU: 1 PID: 2370 at lib/debugobjects.c:303 debug_object_is_on_stack lib/debugobjects.c:303 [inline]
WARNING: CPU: 1 PID: 2370 at lib/debugobjects.c:303 __debug_object_init.cold.10+0x6b/0x2b0 lib/debugobjects.c:329