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: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 99a091e..955dbc8 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -620,7 +620,9 @@
 				 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);