FYI, we noticed the below changes on

commit 5ad6300524c0332ac67e912c20d6e5cf262ba58f ("genetlink: disallow subscribing to unknown mcast groups")

Although the frequency decreased a lot, from 100% to about 8.33%, we still find the warning in dmesg after applying the commit.

[  299.872857] ------------[ cut here ]------------
[  300.039960] WARNING: CPU: 0 PID: 804 at net/netlink/genetlink.c:1037 genl_unbind+0xc0/0xd0()
[  300.360780] CPU: 0 PID: 804 Comm: trinity-main Not tainted 3.19.0-rc4-00160-g5ad6300 #11
[  300.360783] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  300.360793]  ffffffff823ad820 ffff88001556be68 ffffffff81d86b84 0000000000000065
[  300.360795]  0000000000000000 ffff88001556bea8 ffffffff810c2f30 ffffffff82635dc0
[  300.360796]  0000000000000000 ffffffff82635dc0 0000000000000001 ffffffff836d7000
[  300.360799] Call Trace:
[  300.361185]  [<ffffffff81d86b84>] dump_stack+0x4f/0x7b
[  300.361254]  [<ffffffff810c2f30>] warn_slowpath_common+0x80/0xc0
[  300.361256]  [<ffffffff810c3035>] warn_slowpath_null+0x15/0x20
[  300.361270]  [<ffffffff81d7a250>] genl_unbind+0xc0/0xd0
[  300.361272]  [<ffffffff81d7782b>] netlink_setsockopt+0x24b/0x270
[  300.361279]  [<ffffffff81d3d3be>] SyS_setsockopt+0x5e/0xc0
[  300.361285]  [<ffffffff81d95f29>] system_call_fastpath+0x12/0x17
[  300.361296] ---[ end trace 5d4dac2c7bb8ca45 ]---

Thanks,
Huang, Ying