IPv4: Oversized IP packet from 172.20.1.11

===============================
[ INFO: suspicious RCU usage. ]
4.9.78-g68d447c #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 modprobe/5139:
 #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff810de399>] __do_page_fault+0x319/0xd40 arch/x86/mm/fault.c:1336
 #1:  (rcu_read_lock){......}, at: [<ffffffff8143649a>] filemap_map_pages+0xfa/0xd70 mm/filemap.c:2230
 #2:  (&(ptlock_ptr(page))->rlock#2){+.+...}, at: [<ffffffff814cdc91>] spin_lock include/linux/spinlock.h:302 [inline]
 #2:  (&(ptlock_ptr(page))->rlock#2){+.+...}, at: [<ffffffff814cdc91>] pte_alloc_one_map mm/memory.c:2886 [inline]
 #2:  (&(ptlock_ptr(page))->rlock#2){+.+...}, at: [<ffffffff814cdc91>] alloc_set_pte+0xd51/0x1450 mm/memory.c:2984
 #3:  (rcu_callback){......}, at: [<ffffffff81293257>] __rcu_reclaim kernel/rcu/rcu.h:108 [inline]
 #3:  (rcu_callback){......}, at: [<ffffffff81293257>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 #3:  (rcu_callback){......}, at: [<ffffffff81293257>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 #3:  (rcu_callback){......}, at: [<ffffffff81293257>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 #3:  (rcu_callback){......}, at: [<ffffffff81293257>] rcu_process_callbacks+0x977/0x1300 kernel/rcu/tree.c:3037

stack backtrace:
CPU: 1 PID: 5139 Comm: modprobe Not tainted 4.9.78-g68d447c #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801db307d50 ffffffff81d943a9 ffff8801cd236000 0000000000000000
 0000000000000002 ffffffff83a6d440 ffff8801cd7cc158 ffff8801db307d80
 ffffffff81238329 ffff8801cd7cc000 ffff8801c4513b48 ffff8801c4513348
Call Trace:
 <IRQ> [   27.047053]  [<ffffffff81d943a9>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [   27.047053]  [<ffffffff81d943a9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81238329>] lockdep_rcu_suspicious+0x139/0x180 kernel/locking/lockdep.c:4455
 [<ffffffff8128fb28>] synchronize_rcu+0x68/0x90 kernel/rcu/tree_plugin.h:669
 [<ffffffff83583d25>] __l2tp_session_unhash+0x3d5/0x550 net/l2tp/l2tp_core.c:1792
 [<ffffffff83584087>] l2tp_tunnel_closeall+0x1e7/0x3a0 net/l2tp/l2tp_core.c:1364
 [<ffffffff835849ae>] l2tp_tunnel_destruct+0x30e/0x5a0 net/l2tp/l2tp_core.c:1324
 [<ffffffff82ee5033>] __sk_destruct+0x53/0x570 net/core/sock.c:1428
 [<ffffffff81293178>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff81293178>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff81293178>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff81293178>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff81293178>] rcu_process_callbacks+0x898/0x1300 kernel/rcu/tree.c:3037
 [<ffffffff838b98c6>] __do_softirq+0x206/0x951 kernel/softirq.c:284
 [<ffffffff81146be5>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff81146be5>] irq_exit+0x165/0x190 kernel/softirq.c:405
 [<ffffffff838b84db>] exiting_irq arch/x86/include/asm/apic.h:659 [inline]
 [<ffffffff838b84db>] smp_apic_timer_interrupt+0x7b/0xa0 arch/x86/kernel/apic/apic.c:960
 [<ffffffff838b4760>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:752
 <EOI> [   27.165876]  [<ffffffff8136b184>] ? __sanitizer_cov_trace_pc+0x4/0x50 kernel/kcov.c:93
 [<ffffffff814cd5b9>] alloc_set_pte+0x679/0x1450 mm/memory.c:3005
 [<ffffffff81436e7c>] filemap_map_pages+0xadc/0xd70 mm/filemap.c:2289
 [<ffffffff814d03dd>] do_fault_around mm/memory.c:3109 [inline]
 [<ffffffff814d03dd>] do_read_fault mm/memory.c:3149 [inline]
 [<ffffffff814d03dd>] do_fault mm/memory.c:3289 [inline]
 [<ffffffff814d03dd>] handle_pte_fault mm/memory.c:3490 [inline]
 [<ffffffff814d03dd>] __handle_mm_fault mm/memory.c:3577 [inline]
 [<ffffffff814d03dd>] handle_mm_fault+0x1a6d/0x2530 mm/memory.c:3614
 [<ffffffff810de642>] __do_page_fault+0x5c2/0xd40 arch/x86/mm/fault.c:1407
 [<ffffffff810dede7>] do_page_fault+0x27/0x30 arch/x86/mm/fault.c:1470
 [<ffffffff838b3fc8>] page_fault+0x28/0x30 arch/x86/entry/entry_64.S:1055
ODEBUG: object is not on stack, but annotated
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5139 at lib/debugobjects.c:300 debug_object_is_on_stack lib/debugobjects.c:300 [inline]
WARNING: CPU: 1 PID: 5139 at lib/debugobjects.c:300 __debug_object_init+0x526/0xc40 lib/debugobjects.c:326