x86, mm: Trim memory in memblock to be page aligned

We will not map partial pages, so need to make sure memblock
allocation will not allocate those bytes out.

Also we will use for_each_mem_pfn_range() to loop to map memory
range to keep them consistent.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/CAE9FiQVZirvaBMFYRfXMmWEcHbKSicQEHz4VAwUv0xFCk51ZNw@mail.gmail.com
Acked-by: Jacob Shin <jacob.shin@amd.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org>

arch/x86/kernel/e820.c

@@ -1077,6 +1077,9 @@ void __init memblock_x86_fill(void)
 		memblock_add(ei->addr, ei->size);
 	}
 
+	/* throw away partial pages */
+	memblock_trim_memory(PAGE_SIZE);
+
 	memblock_dump_all();
 }
 

include/linux/memblock.h

@@ -57,6 +57,7 @@ int memblock_add(phys_addr_t base, phys_addr_t size);
 int memblock_remove(phys_addr_t base, phys_addr_t size);
 int memblock_free(phys_addr_t base, phys_addr_t size);
 int memblock_reserve(phys_addr_t base, phys_addr_t size);
+void memblock_trim_memory(phys_addr_t align);
 
 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
 void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn,

mm/memblock.c

@@ -930,6 +930,30 @@ int __init_memblock memblock_is_region_reserved(phys_addr_t base, phys_addr_t si
 	return memblock_overlaps_region(&memblock.reserved, base, size) >= 0;
 }
 
+void __init_memblock memblock_trim_memory(phys_addr_t align)
+{
+	int i;
+	phys_addr_t start, end, orig_start, orig_end;
+	struct memblock_type *mem = &memblock.memory;
+
+	for (i = 0; i < mem->cnt; i++) {
+		orig_start = mem->regions[i].base;
+		orig_end = mem->regions[i].base + mem->regions[i].size;
+		start = round_up(orig_start, align);
+		end = round_down(orig_end, align);
+
+		if (start == orig_start && end == orig_end)
+			continue;
+
+		if (start < end) {
+			mem->regions[i].base = start;
+			mem->regions[i].size = end - start;
+		} else {
+			memblock_remove_region(mem, i);
+			i--;
+		}
+	}
+}
 
 void __init_memblock memblock_set_current_limit(phys_addr_t limit)
 {