slub: fix panic with DISCONTIGMEM

commit 4a5fa359 upstream.

Slub makes assumptions about page_to_nid() which are violated by
DISCONTIGMEM and !NUMA.  This violation results in a panic because
page_to_nid() can be non-zero for pages in the discontiguous ranges and
this leads to a null return by get_node().  The assertion by the
maintainer is that DISCONTIGMEM should only be allowed when NUMA is also
defined.  However, at least six architectures: alpha, ia64, m32r, m68k,
mips, parisc violate this.  The panic is a regression against slab, so
just mark slub broken in the problem configuration to prevent users
reporting these panics.

Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

(cherry picked from commit 7c650d5dfafac48213c0a652b7b1a18a3c391538)