initcall kmem_cache cpu 1 oops

[Hugh Dickins]

I don't know if it's right or wrong for initcalls to happen on cpus
other than 0.  But with CONFIG_NR_SIBLINGS_2 on 2*HT*P4 in 2.5.69-mm1
(I didn't try 2.5.68-mm, but 2.5.69 okay) I have sock_init run on cpu 0
setting sock_inode_cachep and its array[0], then later rtnetlink_init on
cpu 1, causing kmem_cache_alloc oops on NULL sock_inode_cachep->array[1]:
g_cpucache_up is still PARTIAL, cpucache_init is yet to be called.

Before 2.5.68-mm3 rtnetlink_init was invoked from within sock_init, but
it's now from a separate netlink_proto_init: so that's another source
of doubt.  For now I have CONFIG_NR_SIBLINGS_0 instead (from a vague
suspicion that CONFIG_SHARE_RUNQUEUE work might have caused unexpectedly
early switch from cpu 0 to 1), and that works around it for me: but I'm
not pointing any finger of blame, I don't know the axioms here at all.

Hugh