======================================
| [ 417.706360][ T10] #2: ffffffff8d19de50 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net (net/core/net_namespace.c:594) 
| [ 417.706586][ T10] #3: ffff888003f8b998 (&hashinfo->ehash_locks[i]){+.-.}-{2:2}, at: inet_twsk_deschedule_put (net/ipv4/inet_timewait_sock.c:243) 
| [  417.706838][   T10]
| [  417.706838][   T10] stack backtrace:
[  417.707175][   T10] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  417.707445][   T10] Workqueue: netns cleanup_net
[  417.707580][   T10] Call Trace:
[  417.707675][   T10]  <TASK>
[ 417.707738][ T10] dump_stack_lvl (lib/dump_stack.c:117) 
[ 417.707862][ T10] check_noncircular (kernel/locking/lockdep.c:2187) 
[ 417.707986][ T10] ? __pfx_check_noncircular (kernel/locking/lockdep.c:2163) 
[ 417.708108][ T10] ? __pfx_stack_trace_save (kernel/stacktrace.c:114) 
[ 417.708231][ T10] ? alloc_chain_hlocks (kernel/locking/lockdep.c:3501) 
[ 417.708356][ T10] check_prev_add (kernel/locking/lockdep.c:3135) 
[ 417.708479][ T10] validate_chain (kernel/locking/lockdep.c:3254 kernel/locking/lockdep.c:3869) 
[ 417.708600][ T10] ? __pfx_validate_chain (kernel/locking/lockdep.c:3825) 
[ 417.708722][ T10] ? hlock_class (./arch/x86/include/asm/bitops.h:227 ./arch/x86/include/asm/bitops.h:239 ./include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:228) 
[ 417.708844][ T10] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 417.708940][ T10] __lock_acquire (kernel/locking/lockdep.c:5137) 
[ 417.709062][ T10] ? __lock_acquire (kernel/locking/lockdep.c:5133) 
[ 417.709196][ T10] ? __timer_delete_sync (kernel/time/timer.c:1648 (discriminator 1)) 
[ 417.709319][ T10] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5756) 
[ 417.709440][ T10] ? __timer_delete_sync (kernel/time/timer.c:1648 (discriminator 1)) 
[ 417.709561][ T10] ? inet_twsk_deschedule_put (net/ipv4/inet_timewait_sock.c:243) 
[ 417.709683][ T10] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 417.709808][ T10] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 417.709928][ T10] ? __timer_delete_sync (kernel/time/timer.c:1648 (discriminator 1)) 
[ 417.710048][ T10] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 417.710167][ T10] ? __timer_delete_sync (kernel/time/timer.c:1648 (discriminator 1)) 
[ 417.710288][ T10] __timer_delete_sync (kernel/time/timer.c:1649 (discriminator 1)) 
[ 417.710409][ T10] ? __timer_delete_sync (kernel/time/timer.c:1648 (discriminator 1)) 
[ 417.710529][ T10] inet_twsk_deschedule_put (net/ipv4/inet_timewait_sock.c:243) 
[ 417.710648][ T10] ? inet_twsk_purge (./include/linux/rcupdate.h:339 ./include/linux/rcupdate.h:814 net/ipv4/inet_timewait_sock.c:328) 
[ 417.710768][ T10] inet_twsk_purge (net/ipv4/inet_timewait_sock.c:331) 
[ 417.710891][ T10] ? inet_twsk_purge (./include/linux/rcupdate.h:329 ./include/linux/rcupdate.h:781 net/ipv4/inet_timewait_sock.c:308) 
[ 417.711011][ T10] ? __pfx_inet_twsk_purge (net/ipv4/inet_timewait_sock.c:295) 
[ 417.711129][ T10] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 417.711222][ T10] tcp_twsk_purge (net/ipv4/tcp_minisocks.c:402) 
[ 417.711348][ T10] tcp_sk_exit_batch (net/ipv4/tcp_ipv4.c:3507) 
[ 417.711470][ T10] cleanup_net (net/core/net_namespace.c:636 (discriminator 3)) 
[ 417.711589][ T10] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 417.711710][ T10] ? __pfx_cleanup_net (net/core/net_namespace.c:581) 
[ 417.711834][ T10] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 417.711957][ T10] ? process_one_work (kernel/workqueue.c:3230) 
[ 417.712083][ T10] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 417.712205][ T10] ? process_one_work (kernel/workqueue.c:3230) 
[ 417.712327][ T10] process_one_work (kernel/workqueue.c:3254) 
[ 417.712448][ T10] ? __pfx___lock_release (kernel/locking/lockdep.c:5406) 
[ 417.712570][ T10] ? __pfx_process_one_work (kernel/workqueue.c:3156) 
[ 417.712696][ T10] ? assign_work (kernel/workqueue.c:1209) 
[ 417.712821][ T10] worker_thread (kernel/workqueue.c:3329 kernel/workqueue.c:3416) 
[ 417.712949][ T10] ? __pfx_worker_thread (kernel/workqueue.c:3362) 
[ 417.713069][ T10] kthread (kernel/kthread.c:388) 
[ 417.713158][ T10] ? __pfx_kthread (kernel/kthread.c:341) 
[ 417.713279][ T10] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 417.713401][ T10] ? __pfx_kthread (kernel/kthread.c:341) 


Finger prints:
dump_stack_lvl:check_noncircular:check_prev_add:validate_chain