======================================
| [ 775.432977][ T10] #2: ffffffff90f9c1d0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net (net/core/net_namespace.c:594) 
| [ 775.433259][ T10] #3: ffff888003d539d8 (&hashinfo->ehash_locks[i]){+.-.}-{2:2}, at: inet_twsk_deschedule_put (net/ipv4/inet_timewait_sock.c:243) 
| [  775.433568][   T10]
| [  775.433568][   T10] stack backtrace:
[  775.433984][   T10] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[  775.434409][   T10] Workqueue: netns cleanup_net
[  775.434579][   T10] Call Trace:
[  775.434688][   T10]  <TASK>
[ 775.434762][ T10] dump_stack_lvl (lib/dump_stack.c:117) 
[ 775.434928][ T10] check_noncircular (kernel/locking/lockdep.c:2187) 
[ 775.435307][ T10] ? __pfx_check_noncircular (kernel/locking/lockdep.c:2163) 
[ 775.435529][ T10] ? __pfx_stack_trace_save (kernel/stacktrace.c:114) 
[ 775.435687][ T10] ? alloc_chain_hlocks (kernel/locking/lockdep.c:3501) 
[ 775.435896][ T10] check_prev_add (kernel/locking/lockdep.c:3135) 
[ 775.436211][ T10] validate_chain (kernel/locking/lockdep.c:3254 kernel/locking/lockdep.c:3869) 
[ 775.436364][ T10] ? __pfx_validate_chain (kernel/locking/lockdep.c:3825) 
[ 775.436513][ 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) 
[ 775.436673][ T10] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 775.436782][ T10] __lock_acquire (kernel/locking/lockdep.c:5137) 
[ 775.436926][ T10] ? __lock_acquire (kernel/locking/lockdep.c:5132) 
[ 775.437078][ T10] ? __timer_delete_sync (kernel/time/timer.c:1648 (discriminator 1)) 
[ 775.437316][ T10] lock_acquire.part.0 (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5756) 
[ 775.437473][ T10] ? __timer_delete_sync (kernel/time/timer.c:1648 (discriminator 1)) 
[ 775.437700][ T10] ? inet_twsk_deschedule_put (net/ipv4/inet_timewait_sock.c:243) 
[ 775.437855][ T10] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 775.437995][ T10] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 775.438163][ T10] ? __timer_delete_sync (kernel/time/timer.c:1648 (discriminator 1)) 
[ 775.438383][ T10] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 775.438538][ T10] ? __timer_delete_sync (kernel/time/timer.c:1648 (discriminator 1)) 
[ 775.438688][ T10] __timer_delete_sync (kernel/time/timer.c:1649 (discriminator 1)) 
[ 775.438840][ T10] ? __timer_delete_sync (kernel/time/timer.c:1648 (discriminator 1)) 
[ 775.438979][ T10] inet_twsk_deschedule_put (net/ipv4/inet_timewait_sock.c:243) 
[ 775.439239][ T10] ? inet_twsk_purge (./include/linux/rcupdate.h:339 ./include/linux/rcupdate.h:814 net/ipv4/inet_timewait_sock.c:328) 
[ 775.439379][ T10] inet_twsk_purge (net/ipv4/inet_timewait_sock.c:331) 
[ 775.439537][ T10] ? inet_twsk_purge (./include/linux/rcupdate.h:329 ./include/linux/rcupdate.h:781 net/ipv4/inet_timewait_sock.c:308) 
[ 775.439680][ T10] ? __pfx_inet_twsk_purge (net/ipv4/inet_timewait_sock.c:295) 
[ 775.439931][ T10] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 3)) 
[ 775.440056][ T10] tcp_twsk_purge (net/ipv4/tcp_minisocks.c:402) 
[ 775.440208][ T10] tcp_sk_exit_batch (net/ipv4/tcp_ipv4.c:3507) 
[ 775.440353][ T10] cleanup_net (net/core/net_namespace.c:636 (discriminator 3)) 
[ 775.440495][ T10] ? __pfx_lock_acquire.part.0 (kernel/locking/lockdep.c:5719) 
[ 775.440637][ T10] ? __pfx_cleanup_net (net/core/net_namespace.c:581) 
[ 775.440777][ T10] ? trace_lock_acquire (./include/trace/events/lock.h:24 (discriminator 52)) 
[ 775.440916][ T10] ? process_one_work (kernel/workqueue.c:3230) 
[ 775.441078][ T10] ? lock_acquire (kernel/locking/lockdep.c:5727) 
[ 775.441293][ T10] ? process_one_work (kernel/workqueue.c:3230) 
[ 775.441441][ T10] process_one_work (kernel/workqueue.c:3254) 
[ 775.441584][ T10] ? __pfx___lock_release (kernel/locking/lockdep.c:5406) 
[ 775.441723][ T10] ? __pfx_process_one_work (kernel/workqueue.c:3156) 
[ 775.441931][ T10] ? assign_work (kernel/workqueue.c:1209) 
[ 775.442084][ T10] worker_thread (kernel/workqueue.c:3329 kernel/workqueue.c:3416) 
[ 775.442228][ T10] ? __pfx_worker_thread (kernel/workqueue.c:3362) 
[ 775.442376][ T10] kthread (kernel/kthread.c:388) 
[ 775.442562][ T10] ? __pfx_kthread (kernel/kthread.c:341) 
[ 775.442717][ T10] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 775.442947][ T10] ? __pfx_kthread (kernel/kthread.c:341) 


Finger prints:
dump_stack_lvl:check_noncircular:check_prev_add:validate_chain