WARNING in __debug_object_init

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 960923fd Merge 4.9.89 into android-4.9
git tree: android-4.9
console output: https://syzkaller.appspot.com/x/log.txt?x=10b9b2ab800000
kernel config: https://syzkaller.appspot.com/x/.config?x=b6a875e0d2e58430
dashboard link: https://syzkaller.appspot.com/bug?extid=c31bf57e73d81cfa6215
compiler: gcc (GCC) 7.1.1 20170620
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11cdab33800000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16b45cab800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c31bf5...@syzkaller.appspotmail.com

pktgen: kernel_thread() failed for cpu 1
pktgen: Cannot create thread for cpu 1 (-4)
pktgen: Initialization failed for all threads
ODEBUG: object is not on stack, but annotated
------------[ cut here ]------------
WARNING: CPU: 1 PID: 0 at lib/debugobjects.c:300 debug_object_is_on_stack
lib/debugobjects.c:300 [inline]
WARNING: CPU: 1 PID: 0 at lib/debugobjects.c:300
__debug_object_init+0x526/0xc40 lib/debugobjects.c:326
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.89-g960923f #61
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
ffff8801db307a08 ffffffff81d96069 ffffffff83a482c0 ffff8801db307ae0
ffffffff83c19700 ffffffff81dfefb6 0000000000000009 ffff8801db307ad0
ffffffff8142fbd1 0000000041b58ab3 ffffffff8418bd08 ffffffff8142fa15
Call Trace:
<IRQ> [ 150.631700] [<ffffffff81d96069>] __dump_stack
lib/dump_stack.c:15 [inline]
<IRQ> [ 150.631700] [<ffffffff81d96069>] dump_stack+0xc1/0x128
lib/dump_stack.c:51
[<ffffffff8142fbd1>] panic+0x1bc/0x3a8 kernel/panic.c:179
[<ffffffff81131894>] __warn+0x1c4/0x1e0 kernel/panic.c:542
[<ffffffff81131afc>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585
[<ffffffff81dfefb6>] debug_object_is_on_stack lib/debugobjects.c:300
[inline]
[<ffffffff81dfefb6>] __debug_object_init+0x526/0xc40 lib/debugobjects.c:326
[<ffffffff81dff709>] debug_object_init_on_stack+0x19/0x20
lib/debugobjects.c:378
[<ffffffff81287a93>] init_rcu_head_on_stack kernel/rcu/update.c:403
[inline]
[<ffffffff81287a93>] __wait_rcu_gp+0x93/0x1b0 kernel/rcu/update.c:358
[<ffffffff81290251>] synchronize_rcu.part.65+0x101/0x110
kernel/rcu/tree_plugin.h:678
[<ffffffff81290287>] synchronize_rcu+0x27/0x90 kernel/rcu/tree_plugin.h:679
[<ffffffff83588b35>] __l2tp_session_unhash+0x3d5/0x550
net/l2tp/l2tp_core.c:1792
[<ffffffff83588e97>] l2tp_tunnel_closeall+0x1e7/0x3a0
net/l2tp/l2tp_core.c:1364
[<ffffffff835897be>] l2tp_tunnel_destruct+0x30e/0x5a0
net/l2tp/l2tp_core.c:1324
[<ffffffff82ee8053>] __sk_destruct+0x53/0x570 net/core/sock.c:1428
[<ffffffff81293918>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
[<ffffffff81293918>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
[<ffffffff81293918>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
[<ffffffff81293918>] __rcu_process_callbacks kernel/rcu/tree.c:3020
[inline]
[<ffffffff81293918>] rcu_process_callbacks+0x898/0x1300
kernel/rcu/tree.c:3037
[<ffffffff838be5d6>] __do_softirq+0x206/0x951 kernel/softirq.c:284
[<ffffffff81147315>] invoke_softirq kernel/softirq.c:364 [inline]
[<ffffffff81147315>] irq_exit+0x165/0x190 kernel/softirq.c:405
[<ffffffff838bd1eb>] exiting_irq arch/x86/include/asm/apic.h:659 [inline]
[<ffffffff838bd1eb>] smp_apic_timer_interrupt+0x7b/0xa0
arch/x86/kernel/apic/apic.c:960
[<ffffffff838b9470>] apic_timer_interrupt+0xa0/0xb0
arch/x86/entry/entry_64.S:648
<EOI> [ 150.848166] [<ffffffff838b6756>] ? native_safe_halt+0x6/0x10
arch/x86/include/asm/irqflags.h:53
[<ffffffff838b5d85>] arch_safe_halt arch/x86/include/asm/paravirt.h:104
[inline]
[<ffffffff838b5d85>] default_idle+0x55/0x360 arch/x86/kernel/process.c:295
[<ffffffff8106be0a>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:286
[<ffffffff838b6b96>] default_idle_call+0x36/0x60 kernel/sched/idle.c:97
[<ffffffff81226cb0>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
[<ffffffff81226cb0>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
[<ffffffff81226cb0>] cpu_startup_entry+0x2b0/0x380 kernel/sched/idle.c:303
[<ffffffff810b0693>] start_secondary+0x303/0x3e0
arch/x86/kernel/smpboot.c:254
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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