syzbot

=============================
WARNING: suspicious RCU usage
4.15.0-rc6-next-20180105+ #89 Not tainted
-----------------------------
net/netfilter/ipset/ip_set_core.c:2057 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
3 locks held by kworker/u4:1/21:
 #0:  ((wq_completion)"%s""netns"){+.+.}, at: [<000000000da56a8f>] process_one_work+0x71f/0x14a0 kernel/workqueue.c:2083
 #1:  (net_cleanup_work){+.+.}, at: [<00000000b46dc045>] process_one_work+0x757/0x14a0 kernel/workqueue.c:2087
 #2:  (net_mutex){+.+.}, at: [<00000000a306ec37>] cleanup_net+0x139/0x8b0 net/core/net_namespace.c:450

stack backtrace:
CPU: 1 PID: 21 Comm: kworker/u4:1 Not tainted 4.15.0-rc6-next-20180105+ #89
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x137/0x198 lib/dump_stack.c:53
 lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4585
 ip_set_net_exit+0x2c6/0x480 net/netfilter/ipset/ip_set_core.c:2057
 ops_exit_list.isra.6+0xae/0x150 net/core/net_namespace.c:142
 cleanup_net+0x3f3/0x8b0 net/core/net_namespace.c:484
 process_one_work+0x801/0x14a0 kernel/workqueue.c:2112
 worker_thread+0xe0/0x1010 kernel/workqueue.c:2246
 kthread+0x33c/0x400 kernel/kthread.c:238
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:524