diff --git a/kernel/resource.c b/kernel/resource.c
index 155ec873ea4d..38b8d11c9eaf 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -318,24 +318,27 @@ int release_resource(struct resource *old)
 
 EXPORT_SYMBOL(release_resource);
 
-/*
- * Finds the lowest iomem resource existing within [res->start..res->end].
- * The caller must specify res->start, res->end, res->flags, and optionally
- * desc.  If found, returns 0, res is overwritten, if not found, returns -1.
- * This function walks the whole tree and not just first level children until
- * and unless first_level_children_only is true.
+/**
+ * Finds the lowest iomem resource that covers part of [start..end].  The
+ * caller must specify start, end, flags, and desc (which may be
+ * IORES_DESC_NONE).
+ *
+ * If a resource is found, returns 0 and *res is overwritten with the part
+ * of the resource that's within [start..end]; if none is found, returns
+ * -1.
+ *
+ * This function walks the whole tree and not just first level children
+ * unless @first_level_children_only is true.
  */
-static int find_next_iomem_res(struct resource *res, unsigned long desc,
-			       bool first_level_children_only)
+static int find_next_iomem_res(resource_size_t start, resource_size_t end,
+			       unsigned long flags, unsigned long desc,
+			       bool first_level_children_only,
+			       struct resource *res)
 {
-	resource_size_t start, end;
 	struct resource *p;
 	bool sibling_only = false;
 
 	BUG_ON(!res);
-
-	start = res->start;
-	end = res->end;
 	BUG_ON(start >= end);
 
 	if (first_level_children_only)
@@ -344,7 +347,7 @@ static int find_next_iomem_res(struct resource *res, unsigned long desc,
 	read_lock(&resource_lock);
 
 	for (p = iomem_resource.child; p; p = next_resource(p, sibling_only)) {
-		if ((p->flags & res->flags) != res->flags)
+		if ((p->flags & flags) != flags)
 			continue;
 		if ((desc != IORES_DESC_NONE) && (desc != p->desc))
 			continue;
@@ -359,32 +362,31 @@ static int find_next_iomem_res(struct resource *res, unsigned long desc,
 	read_unlock(&resource_lock);
 	if (!p)
 		return -1;
+
 	/* copy data */
-	if (res->start < p->start)
-		res->start = p->start;
-	if (res->end > p->end)
-		res->end = p->end;
+	res->start = max(start, p->start);
+	res->end = min(end, p->end);
 	res->flags = p->flags;
 	res->desc = p->desc;
 	return 0;
 }
 
-static int __walk_iomem_res_desc(struct resource *res, unsigned long desc,
-				 bool first_level_children_only,
-				 void *arg,
+static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,
+				 unsigned long flags, unsigned long desc,
+				 bool first_level_children_only, void *arg,
 				 int (*func)(struct resource *, void *))
 {
-	u64 orig_end = res->end;
+	struct resource res;
 	int ret = -1;
 
-	while ((res->start < res->end) &&
-	       !find_next_iomem_res(res, desc, first_level_children_only)) {
-		ret = (*func)(res, arg);
+	while (start < end &&
+	       !find_next_iomem_res(start, end, flags, desc,
+				    first_level_children_only, &res)) {
+		ret = (*func)(&res, arg);
 		if (ret)
 			break;
 
-		res->start = res->end + 1;
-		res->end = orig_end;
+		start = res.end + 1;
 	}
 
 	return ret;
@@ -407,13 +409,7 @@ static int __walk_iomem_res_desc(struct resource *res, unsigned long desc,
 int walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start,
 		u64 end, void *arg, int (*func)(struct resource *, void *))
 {
-	struct resource res;
-
-	res.start = start;
-	res.end = end;
-	res.flags = flags;
-
-	return __walk_iomem_res_desc(&res, desc, false, arg, func);
+	return __walk_iomem_res_desc(start, end, flags, desc, false, arg, func);
 }
 EXPORT_SYMBOL_GPL(walk_iomem_res_desc);
 
@@ -427,13 +423,9 @@ EXPORT_SYMBOL_GPL(walk_iomem_res_desc);
 int walk_system_ram_res(u64 start, u64 end, void *arg,
 				int (*func)(struct resource *, void *))
 {
-	struct resource res;
+	unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
 
-	res.start = start;
-	res.end = end;
-	res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
-
-	return __walk_iomem_res_desc(&res, IORES_DESC_NONE, true,
+	return __walk_iomem_res_desc(start, end, flags, IORES_DESC_NONE, true,
 				     arg, func);
 }
 
@@ -444,13 +436,9 @@ int walk_system_ram_res(u64 start, u64 end, void *arg,
 int walk_mem_res(u64 start, u64 end, void *arg,
 		 int (*func)(struct resource *, void *))
 {
-	struct resource res;
+	unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 
-	res.start = start;
-	res.end = end;
-	res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
-
-	return __walk_iomem_res_desc(&res, IORES_DESC_NONE, true,
+	return __walk_iomem_res_desc(start, end, flags, IORES_DESC_NONE, true,
 				     arg, func);
 }
 
@@ -464,25 +452,25 @@ int walk_mem_res(u64 start, u64 end, void *arg,
 int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 		void *arg, int (*func)(unsigned long, unsigned long, void *))
 {
+	resource_size_t start, end;
+	unsigned long flags;
 	struct resource res;
 	unsigned long pfn, end_pfn;
-	u64 orig_end;
 	int ret = -1;
 
-	res.start = (u64) start_pfn << PAGE_SHIFT;
-	res.end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1;
-	res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
-	orig_end = res.end;
-	while ((res.start < res.end) &&
-		(find_next_iomem_res(&res, IORES_DESC_NONE, true) >= 0)) {
+	start = (u64) start_pfn << PAGE_SHIFT;
+	end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1;
+	flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
+	while (start < end &&
+	       !find_next_iomem_res(start, end, flags, IORES_DESC_NONE,
+				    true, &res)) {
 		pfn = (res.start + PAGE_SIZE - 1) >> PAGE_SHIFT;
 		end_pfn = (res.end + 1) >> PAGE_SHIFT;
 		if (end_pfn > pfn)
 			ret = (*func)(pfn, end_pfn - pfn, arg);
 		if (ret)
 			break;
-		res.start = res.end + 1;
-		res.end = orig_end;
+		start = res.end + 1;
 	}
 	return ret;
 }