2.6.23-git7, using SLAB (not SLUB) [config attached]:

# modprobe clip
# rmmod clip
# modprobe clip

results in panic:

kmem_cache_create: duplicate cache clip_arp_cache

Call Trace:
 [<ffffffff8028c682>] kmem_cache_create+0x3bf/0x3fd
 [<ffffffff8046ba1d>] neigh_table_init_no_netlink+0x6c/0x242
 [<ffffffff8800a010>] :clip:atm_clip_init+0x10/0x8a
 [<ffffffff80258ba4>] sys_init_module+0x146c/0x15cd
 [<ffffffff8046be0a>] neigh_lookup+0x0/0xd5
 [<ffffffff8020ef44>] syscall_trace_enter+0x95/0x99
 [<ffffffff8020beec>] tracesys+0xdc/0xe1

Kernel panic - not syncing: kmem_cache_create(): failed to create slab `clip_arp_cache'

-- 
~Randy