arch, mm: remove stale mentions of DISCONIGMEM

There are several places that mention DISCONIGMEM in comments or have
stale code guarded by CONFIG_DISCONTIGMEM.

Remove the dead code and update the comments.

Link: https://lkml.kernel.org/r/20210608091316.3622-7-rppt@kernel.org
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-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/ia64/kernel/topology.c

@@ -3,9 +3,8 @@
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  *
- * This file contains NUMA specific variables and functions which can
- * be split away from DISCONTIGMEM and are used on NUMA machines with
- * contiguous memory.
+ * This file contains NUMA specific variables and functions which are used on
+ * NUMA machines with contiguous memory.
  * 		2002/08/07 Erich Focht <efocht@ess.nec.de>
  * Populate cpu entries in sysfs for non-numa systems as well
  *  	Intel Corporation - Ashok Raj

arch/ia64/mm/numa.c

@@ -3,9 +3,8 @@
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  *
- * This file contains NUMA specific variables and functions which can
- * be split away from DISCONTIGMEM and are used on NUMA machines with
- * contiguous memory.
+ * This file contains NUMA specific variables and functions which are used on
+ * NUMA machines with contiguous memory.
  * 
  *                         2002/08/07 Erich Focht <efocht@ess.nec.de>
  */

arch/mips/include/asm/mmzone.h

@@ -20,10 +20,4 @@
 #define nid_to_addrbase(nid) 0
 #endif
 
-#ifdef CONFIG_DISCONTIGMEM
-
-#define pfn_to_nid(pfn)		pa_to_nid((pfn) << PAGE_SHIFT)
-
-#endif /* CONFIG_DISCONTIGMEM */
-
 #endif /* _ASM_MMZONE_H_ */

arch/mips/mm/init.c

@@ -454,9 +454,6 @@ void __init mem_init(void)
 	BUILD_BUG_ON(IS_ENABLED(CONFIG_32BIT) && (_PFN_SHIFT > PAGE_SHIFT));
 
 #ifdef CONFIG_HIGHMEM
-#ifdef CONFIG_DISCONTIGMEM
-#error "CONFIG_HIGHMEM and CONFIG_DISCONTIGMEM dont work together yet"
-#endif
 	max_mapnr = highend_pfn ? highend_pfn : max_low_pfn;
 #else
 	max_mapnr = max_low_pfn;

arch/nds32/include/asm/memory.h

@@ -76,18 +76,12 @@
  *  virt_to_page(k)	convert a _valid_ virtual address to struct page *
  *  virt_addr_valid(k)	indicates whether a virtual address is valid
  */
-#ifndef CONFIG_DISCONTIGMEM
-
 #define ARCH_PFN_OFFSET		PHYS_PFN_OFFSET
 #define pfn_valid(pfn)		((pfn) >= PHYS_PFN_OFFSET && (pfn) < (PHYS_PFN_OFFSET + max_mapnr))
 
 #define virt_to_page(kaddr)	(pfn_to_page(__pa(kaddr) >> PAGE_SHIFT))
 #define virt_addr_valid(kaddr)	((unsigned long)(kaddr) >= PAGE_OFFSET && (unsigned long)(kaddr) < (unsigned long)high_memory)
 
-#else /* CONFIG_DISCONTIGMEM */
-#error CONFIG_DISCONTIGMEM is not supported yet.
-#endif /* !CONFIG_DISCONTIGMEM */
-
 #define page_to_phys(page)	(page_to_pfn(page) << PAGE_SHIFT)
 
 #endif

arch/xtensa/include/asm/page.h

@@ -192,10 +192,6 @@ static inline unsigned long ___pa(unsigned long va)
 #define pfn_valid(pfn) \
 	((pfn) >= ARCH_PFN_OFFSET && ((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
 
-#ifdef CONFIG_DISCONTIGMEM
-# error CONFIG_DISCONTIGMEM not supported
-#endif
-
 #define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
 #define page_to_virt(page)	__va(page_to_pfn(page) << PAGE_SHIFT)
 #define virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)

include/linux/gfp.h

@@ -494,8 +494,8 @@ static inline int gfp_zonelist(gfp_t flags)
  * There are two zonelists per node, one for all zones with memory and
  * one containing just zones from the node the zonelist belongs to.
  *
- * For the normal case of non-DISCONTIGMEM systems the NODE_DATA() gets
- * optimized to &contig_page_data at compile-time.
+ * For the case of non-NUMA systems the NODE_DATA() gets optimized to
+ * &contig_page_data at compile-time.
  */
 static inline struct zonelist *node_zonelist(int nid, gfp_t flags)
 {