mm: remove unnecessary ia64 code and comment

IA64 has gone with commit cf8e8658 ("arch: Remove Itanium (IA-64)
architecture"), remove unnecessary ia64 special mm code and comment too.

Link: https://lkml.kernel.org/r/20231222070203.2966980-1-wangkefeng.wang@huawei.comSigned-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/Kconfig

@@ -770,7 +770,7 @@ config DEFAULT_MMAP_MIN_ADDR
 	  from userspace allocation.  Keeping a user from writing to low pages
 	  can help reduce the impact of kernel NULL pointer bugs.
 
-	  For most ia64, ppc64 and x86 users with lots of address space
+	  For most ppc64 and x86 users with lots of address space
 	  a value of 65536 is reasonable and should cause no problems.
 	  On arm and other archs it should not be higher than 32768.
 	  Programs which use vm86 functionality or have some need to map

mm/memory.c

@@ -123,9 +123,7 @@ static bool vmf_orig_pte_uffd_wp(struct vm_fault *vmf)
 /*
  * A number of key systems in x86 including ioremap() rely on the assumption
  * that high_memory defines the upper bound on direct map memory, then end
- * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
- * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
- * and ZONE_HIGHMEM.
+ * of ZONE_NORMAL.
  */
 void *high_memory;
 EXPORT_SYMBOL(high_memory);

mm/mm_init.c

@@ -1467,8 +1467,7 @@ void __init set_pageblock_order(void)
 
 	/*
 	 * Assume the largest contiguous order of interest is a huge page.
-	 * This value may be variable depending on boot parameters on IA64 and
-	 * powerpc.
+	 * This value may be variable depending on boot parameters on powerpc.
 	 */
 	pageblock_order = order;
 }
@@ -1629,8 +1628,8 @@ void __init *memmap_alloc(phys_addr_t size, phys_addr_t align,
 #ifdef CONFIG_FLATMEM
 static void __init alloc_node_mem_map(struct pglist_data *pgdat)
 {
-	unsigned long __maybe_unused start = 0;
-	unsigned long __maybe_unused offset = 0;
+	unsigned long start, offset, size, end;
+	struct page *map;
 
 	/* Skip empty nodes */
 	if (!pgdat->node_spanned_pages)
@@ -1638,33 +1637,24 @@ static void __init alloc_node_mem_map(struct pglist_data *pgdat)
 
 	start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
 	offset = pgdat->node_start_pfn - start;
-	/* ia64 gets its own node_mem_map, before this, without bootmem */
-	if (!pgdat->node_mem_map) {
-		unsigned long size, end;
-		struct page *map;
-
-		/*
-		 * The zone's endpoints aren't required to be MAX_ORDER
-		 * aligned but the node_mem_map endpoints must be in order
-		 * for the buddy allocator to function correctly.
-		 */
-		end = pgdat_end_pfn(pgdat);
-		end = ALIGN(end, MAX_ORDER_NR_PAGES);
-		size =  (end - start) * sizeof(struct page);
-		map = memmap_alloc(size, SMP_CACHE_BYTES, MEMBLOCK_LOW_LIMIT,
-				   pgdat->node_id, false);
-		if (!map)
-			panic("Failed to allocate %ld bytes for node %d memory map\n",
-			      size, pgdat->node_id);
-		pgdat->node_mem_map = map + offset;
-	}
-	pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
-				__func__, pgdat->node_id, (unsigned long)pgdat,
-				(unsigned long)pgdat->node_mem_map);
-#ifndef CONFIG_NUMA
 	/*
-	 * With no DISCONTIG, the global mem_map is just set as node 0's
+	 * The zone's endpoints aren't required to be MAX_ORDER
+	 * aligned but the node_mem_map endpoints must be in order
+	 * for the buddy allocator to function correctly.
 	 */
+	end = ALIGN(pgdat_end_pfn(pgdat), MAX_ORDER_NR_PAGES);
+	size =  (end - start) * sizeof(struct page);
+	map = memmap_alloc(size, SMP_CACHE_BYTES, MEMBLOCK_LOW_LIMIT,
+			   pgdat->node_id, false);
+	if (!map)
+		panic("Failed to allocate %ld bytes for node %d memory map\n",
+		      size, pgdat->node_id);
+	pgdat->node_mem_map = map + offset;
+	pr_debug("%s: node %d, pgdat %08lx, node_mem_map %08lx\n",
+		 __func__, pgdat->node_id, (unsigned long)pgdat,
+		 (unsigned long)pgdat->node_mem_map);
+#ifndef CONFIG_NUMA
+	/* the global mem_map is just set as node 0's */
 	if (pgdat == NODE_DATA(0)) {
 		mem_map = NODE_DATA(0)->node_mem_map;
 		if (page_to_pfn(mem_map) != pgdat->node_start_pfn)

mm/page_owner.c

@@ -121,7 +121,6 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags)
 	 * Sometimes page metadata allocation tracking requires more
 	 * memory to be allocated:
 	 * - when new stack trace is saved to stack depot
-	 * - when backtrace itself is calculated (ia64)
 	 */
 	if (current->in_page_owner)
 		return dummy_handle;