binder: 15819:15876 ERROR: BC_REGISTER_LOOPER called without request
binder: 15819:15872 got reply transaction with no transaction stack
binder: 15819:15872 transaction failed 29201/-71, size 0-0 line 2926

===============================
[ INFO: suspicious RCU usage. ]
4.9.112-g9e79039 #59 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
2 locks held by udevd/13450:
 #0:  (rcu_read_lock){......}, at: [<ffffffff815c139a>] dput.part.29+0x2a/0x7b0 fs/dcache.c:790
 #1:  (rcu_callback){......}, at: [<ffffffff812878ae>] __rcu_reclaim kernel/rcu/rcu.h:108 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff812878ae>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff812878ae>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff812878ae>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 #1:  (rcu_callback){......}, at: [<ffffffff812878ae>] rcu_process_callbacks+0x98e/0x12b0 kernel/rcu/tree.c:3037

stack backtrace:
CPU: 0 PID: 13450 Comm: udevd Not tainted 4.9.112-g9e79039 #59
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801db207d60 ffffffff81eb3249 ffff8801c2f56000 0000000000000000
 0000000000000002 ffffffff83c6df20 ffff8801aed23cd8 ffff8801db207d90
 ffffffff814260f0 ffff8801aed23b80 ffff8801d54bee48 ffff8801d54be648
Call Trace:
 <IRQ> 
 [<ffffffff81eb3249>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb3249>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff814260f0>] lockdep_rcu_suspicious.cold.48+0x110/0x141 kernel/locking/lockdep.c:4455
 [<ffffffff81284148>] synchronize_rcu+0x68/0x90 kernel/rcu/tree_plugin.h:675
 [<ffffffff836bd15a>] __l2tp_session_unhash+0x38a/0x520 net/l2tp/l2tp_core.c:1796
 [<ffffffff836bd4e7>] l2tp_tunnel_closeall+0x1f7/0x350 net/l2tp/l2tp_core.c:1364
 [<ffffffff836bdda2>] l2tp_tunnel_destruct+0x2f2/0x590 net/l2tp/l2tp_core.c:1324
 [<ffffffff83021095>] __sk_destruct+0x55/0x590 net/core/sock.c:1428
 [<ffffffff812877ce>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff812877ce>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff812877ce>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff812877ce>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff812877ce>] rcu_process_callbacks+0x8ae/0x12b0 kernel/rcu/tree.c:3037
 [<ffffffff83a00b3b>] __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
 [<ffffffff839ff721>] exiting_irq arch/x86/include/asm/apic.h:659 [inline]
 [<ffffffff839ff721>] smp_apic_timer_interrupt+0x81/0xa0 arch/x86/kernel/apic/apic.c:960
 [<ffffffff839fb8b0>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> 
 [<ffffffff839f95aa>] __raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline]
 [<ffffffff839f95aa>] _raw_spin_unlock+0x1a/0x50 kernel/locking/spinlock.c:183
 [<ffffffff81ee7d52>] spin_unlock include/linux/spinlock.h:347 [inline]
 [<ffffffff81ee7d52>] lockref_put_or_lock+0x62/0x80 lib/lockref.c:146
 [<ffffffff815c1738>] fast_dput fs/dcache.c:678 [inline]
 [<ffffffff815c1738>] dput.part.29+0x3c8/0x7b0 fs/dcache.c:799
 [<ffffffff815c1b3f>] dput+0x1f/0x30 fs/dcache.c:792
 [<ffffffff815aa920>] path_put fs/namei.c:516 [inline]
 [<ffffffff815aa920>] do_unlinkat+0x180/0x680 fs/namei.c:4096
 [<ffffffff815ac95a>] SYSC_unlink fs/namei.c:4128 [inline]
 [<ffffffff815ac95a>] SyS_unlink+0x1a/0x20 fs/namei.c:4126
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f9f53>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
ODEBUG: object ffff8801db207ce8 is NOT on stack ffff8801d3b20000, but annotated
------------[ cut here ]------------
WARNING: CPU: 0 PID: 13450 at lib/debugobjects.c:303 debug_object_is_on_stack lib/debugobjects.c:303 [inline]
WARNING: CPU: 0 PID: 13450 at lib/debugobjects.c:303 __debug_object_init.cold.10+0x6b/0x2b0 lib/debugobjects.c:329