x86: clean up min_low_pfn

for 32bit
we already had early_res support, so don't need to track min_low_pfn.
keep it to 0 always.

also use init_bootmem_node instead of init_bootmem, so don't touch
min_low_pfn.
Signed-off-by: NYinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/mm/init_32.c

@@ -565,11 +565,7 @@ void __init find_low_pfn_range(void)
 {
 	/* it could update max_pfn */
 
-	/*
-	 * partially used pages are not usable - thus
-	 * we are rounding upwards:
-	 */
-	min_low_pfn = PFN_UP(init_pg_tables_end);
+	/* max_low_pfn is 0, we already have early_res support */
 
 	max_low_pfn = max_pfn;
 	if (max_low_pfn > MAXMEM_PFN) {
@@ -694,7 +690,9 @@ void __init setup_bootmem_allocator(void)
 		panic("Cannot find bootmem map of size %ld\n", bootmap_size);
 	reserve_early(bootmap, bootmap + bootmap_size, "BOOTMAP");
 
-	bootmap_size = init_bootmem(bootmap >> PAGE_SHIFT, max_low_pfn);
+	/* don't touch min_low_pfn */
+	bootmap_size = init_bootmem_node(NODE_DATA(0), bootmap >> PAGE_SHIFT,
+					 min_low_pfn, max_low_pfn);
 	printk(KERN_INFO "  mapped low ram: 0 - %08lx\n",
 		 max_pfn_mapped<<PAGE_SHIFT);
 	printk(KERN_INFO "  low ram: %08lx - %08lx\n",

arch/x86/mm/init_64.c

@@ -620,7 +620,9 @@ void __init initmem_init(unsigned long start_pfn, unsigned long end_pfn)
 				 PAGE_SIZE);
 	if (bootmap == -1L)
 		panic("Cannot find bootmem map of size %ld\n", bootmap_size);
-	bootmap_size = init_bootmem(bootmap >> PAGE_SHIFT, end_pfn);
+	/* don't touch min_low_pfn */
+	bootmap_size = init_bootmem_node(NODE_DATA(0), bootmap >> PAGE_SHIFT,
+					 0, end_pfn);
 	e820_register_active_regions(0, start_pfn, end_pfn);
 	free_bootmem_with_active_regions(0, end_pfn);
 	early_res_to_bootmem(0, end_pfn<<PAGE_SHIFT);