diff --git a/mm/bootmem.c b/mm/bootmem.c
index 94ea612..9d03ff6 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -225,6 +225,44 @@
 	return free_all_bootmem_core(NODE_DATA(0)->bdata);
 }
 
+static void __init __free(bootmem_data_t *bdata,
+			unsigned long sidx, unsigned long eidx)
+{
+	unsigned long idx;
+
+	bdebug("nid=%td start=%lx end=%lx\n", bdata - bootmem_node_data,
+		sidx + PFN_DOWN(bdata->node_boot_start),
+		eidx + PFN_DOWN(bdata->node_boot_start));
+
+	for (idx = sidx; idx < eidx; idx++)
+		if (!test_and_clear_bit(idx, bdata->node_bootmem_map))
+			BUG();
+}
+
+static int __init __reserve(bootmem_data_t *bdata, unsigned long sidx,
+			unsigned long eidx, int flags)
+{
+	unsigned long idx;
+	int exclusive = flags & BOOTMEM_EXCLUSIVE;
+
+	bdebug("nid=%td start=%lx end=%lx flags=%x\n",
+		bdata - bootmem_node_data,
+		sidx + PFN_DOWN(bdata->node_boot_start),
+		eidx + PFN_DOWN(bdata->node_boot_start),
+		flags);
+
+	for (idx = sidx; idx < eidx; idx++)
+		if (test_and_set_bit(idx, bdata->node_bootmem_map)) {
+			if (exclusive) {
+				__free(bdata, sidx, idx);
+				return -EBUSY;
+			}
+			bdebug("silent double reserve of PFN %lx\n",
+				idx + PFN_DOWN(bdata->node_boot_start));
+		}
+	return 0;
+}
+
 static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr,
 				     unsigned long size)
 {
@@ -258,14 +296,7 @@
 	if (eidx > bdata->node_low_pfn - PFN_DOWN(bdata->node_boot_start))
 		eidx = bdata->node_low_pfn - PFN_DOWN(bdata->node_boot_start);
 
-	bdebug("nid=%td start=%lx end=%lx\n", bdata - bootmem_node_data,
-		sidx + PFN_DOWN(bdata->node_boot_start),
-		eidx + PFN_DOWN(bdata->node_boot_start));
-
-	for (i = sidx; i < eidx; i++) {
-		if (unlikely(!test_and_clear_bit(i, bdata->node_bootmem_map)))
-			BUG();
-	}
+	__free(bdata, sidx, eidx);
 }
 
 /**
@@ -367,16 +398,7 @@
 	if (eidx > bdata->node_low_pfn - PFN_DOWN(bdata->node_boot_start))
 		eidx = bdata->node_low_pfn - PFN_DOWN(bdata->node_boot_start);
 
-	bdebug("nid=%td start=%lx end=%lx flags=%x\n",
-		bdata - bootmem_node_data,
-		sidx + PFN_DOWN(bdata->node_boot_start),
-		eidx + PFN_DOWN(bdata->node_boot_start),
-		flags);
-
-	for (i = sidx; i < eidx; i++)
-		if (test_and_set_bit(i, bdata->node_bootmem_map))
-			bdebug("hm, page %lx reserved twice.\n",
-				PFN_DOWN(bdata->node_boot_start) + i);
+	return __reserve(bdata, sidx, eidx, flags);
 }
 
 /**
@@ -511,10 +533,9 @@
 		/*
 		 * Reserve the area now:
 		 */
-		for (i = PFN_DOWN(start_off) + merge;
-				i < PFN_UP(end_off); i++)
-			if (test_and_set_bit(i, bdata->node_bootmem_map))
-				BUG();
+		if (__reserve(bdata, PFN_DOWN(start_off) + merge,
+				PFN_UP(end_off), BOOTMEM_EXCLUSIVE))
+			BUG();
 
 		region = phys_to_virt(bdata->node_boot_start + start_off);
 		memset(region, 0, size);