INFO: task hung in addrconf_verify_work (2)

[syzbot]

Hello,

syzbot hit the following crash on net-next commit
18845557fd6fc1998f2d0d8c30467f86db587529 (Thu Mar 29 20:24:06 2018 +0000)
Merge tag 'wireless-drivers-next-for-davem-2018-03-29' of
git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers-next
syzbot dashboard link:
https://syzkaller.appspot.com/bug?extid=4dd9cdeedb2055a91d54

Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=5653128623947776
Kernel config: https://syzkaller.appspot.com/x/.config?id=-37309782588693906
compiler: gcc (GCC) 7.1.1 20170620
CC: [christia...@ubuntu.com dan...@iogearbox.net da...@davemloft.net
dsa...@gmail.com f...@strlen.de jb...@redhat.com ktk...@virtuozzo.com
linux-...@vger.kernel.org lucie...@gmail.com net...@vger.kernel.org
vyas...@gmail.com]

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Reported-by: syzbot+4dd9cd...@syzkaller.appspotmail.com
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Total swap = 0kB
1965969 pages RAM
0 pages HighMem/MovableOnly
333455 pages reserved
device bcsf0 left promiscuous mode
INFO: task kworker/0:6:5878 blocked for more than 120 seconds.
Not tainted 4.16.0-rc6+ #286
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/0:6 D22112 5878 2 0x80000000
Workqueue: ipv6_addrconf addrconf_verify_work
Call Trace:
context_switch kernel/sched/core.c:2862 [inline]
__schedule+0x8fb/0x1ec0 kernel/sched/core.c:3440
schedule+0xf5/0x430 kernel/sched/core.c:3499
schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3557
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74
addrconf_verify_work+0xe/0x20 net/ipv6/addrconf.c:4444
process_one_work+0xc47/0x1bb0 kernel/workqueue.c:2113
worker_thread+0x223/0x1990 kernel/workqueue.c:2247
kthread+0x33c/0x400 kernel/kthread.c:238
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406
INFO: lockdep is turned off.
NMI backtrace for cpu 1
CPU: 1 PID: 869 Comm: khungtaskd Not tainted 4.16.0-rc6+ #286
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x24d lib/dump_stack.c:53
nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103
nmi_trigger_cpumask_backtrace+0x123/0x180 lib/nmi_backtrace.c:62
arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
check_hung_task kernel/hung_task.c:132 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline]
watchdog+0x90c/0xd60 kernel/hung_task.c:249
kthread+0x33c/0x400 kernel/kthread.c:238
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10
arch/x86/include/asm/irqflags.h:54
Kernel panic - not syncing: hung_task: blocked tasks
CPU: 1 PID: 869 Comm: khungtaskd Not tainted 4.16.0-rc6+ #286
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x24d lib/dump_stack.c:53
panic+0x1e4/0x41c kernel/panic.c:183
check_hung_task kernel/hung_task.c:133 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline]
watchdog+0x91d/0xd60 kernel/hung_task.c:249
kthread+0x33c/0x400 kernel/kthread.c:238
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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