alpha: remove DISCONTIGMEM and NUMA

Patch series "Remove DISCONTIGMEM memory model", v3.

SPARSEMEM memory model was supposed to entirely replace DISCONTIGMEM a
(long) while ago.  The last architectures that used DISCONTIGMEM were
updated to use other memory models in v5.11 and it is about the time to
entirely remove DISCONTIGMEM from the kernel.

This set removes DISCONTIGMEM from alpha, arc and m68k, simplifies memory
model selection in mm/Kconfig and replaces usage of redundant
CONFIG_NEED_MULTIPLE_NODES and CONFIG_FLAT_NODE_MEM_MAP with CONFIG_NUMA
and CONFIG_FLATMEM respectively.

I've also removed NUMA support on alpha that was BROKEN for more than 15
years.

There were also minor updates all over arch/ to remove mentions of
DISCONTIGMEM in comments and #ifdefs.

This patch (of 9):

NUMA is marked broken on alpha for more than 15 years and DISCONTIGMEM was
replaced with SPARSEMEM in v5.11.

Remove both NUMA and DISCONTIGMEM support from alpha.

Link: https://lkml.kernel.org/r/20210608091316.3622-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20210608091316.3622-2-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/alpha/kernel/setup.c

@@ -79,11 +79,6 @@ int alpha_l3_cacheshape;
 unsigned long alpha_verbose_mcheck = CONFIG_VERBOSE_MCHECK_ON;
 #endif
 
-#ifdef CONFIG_NUMA
-struct cpumask node_to_cpumask_map[MAX_NUMNODES] __read_mostly;
-EXPORT_SYMBOL(node_to_cpumask_map);
-#endif
-
 /* Which processor we booted from.  */
 int boot_cpuid;
 
@@ -305,7 +300,6 @@ move_initrd(unsigned long mem_limit)
 }
 #endif
 
-#ifndef CONFIG_DISCONTIGMEM
 static void __init
 setup_memory(void *kernel_end)
 {
@@ -389,9 +383,6 @@ setup_memory(void *kernel_end)
 	}
 #endif /* CONFIG_BLK_DEV_INITRD */
 }
-#else
-extern void setup_memory(void *);
-#endif /* !CONFIG_DISCONTIGMEM */
 
 int __init
 page_is_ram(unsigned long pfn)
@@ -618,13 +609,6 @@ setup_arch(char **cmdline_p)
 	       "VERBOSE_MCHECK "
 #endif
 
-#ifdef CONFIG_DISCONTIGMEM
-	       "DISCONTIGMEM "
-#ifdef CONFIG_NUMA
-	       "NUMA "
-#endif
-#endif
-
 #ifdef CONFIG_DEBUG_SPINLOCK
 	       "DEBUG_SPINLOCK "
 #endif