1 files changed, 20 insertions, 13 deletions

diff --git a/kernel/resource.c b/kernel/resource.c
index 915c02e8e5dd..8c15f846e8ef 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -382,7 +382,7 @@ static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,
 				 int (*func)(struct resource *, void *))
 {
 	struct resource res;
-	int ret = -1;
+	int ret = -EINVAL;
 
 	while (start < end &&
 	       !find_next_iomem_res(start, end, flags, desc, first_lvl, &res)) {
@@ -448,12 +448,13 @@ int walk_mem_res(u64 start, u64 end, void *arg,
 				     arg, func);
 }
 
-#if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
-
 /*
  * This function calls the @func callback against all memory ranges of type
  * System RAM which are marked as IORESOURCE_SYSTEM_RAM and IORESOUCE_BUSY.
  * It is to be used only for System RAM.
+ *
+ * This will find System RAM ranges that are children of top-level resources
+ * in addition to top-level System RAM resources.
  */
 int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 			  void *arg, int (*func)(unsigned long, unsigned long, void *))
@@ -462,14 +463,14 @@ int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 	unsigned long flags;
 	struct resource res;
 	unsigned long pfn, end_pfn;
-	int ret = -1;
+	int ret = -EINVAL;
 
 	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)) {
+				    false, &res)) {
 		pfn = (res.start + PAGE_SIZE - 1) >> PAGE_SHIFT;
 		end_pfn = (res.end + 1) >> PAGE_SHIFT;
 		if (end_pfn > pfn)
@@ -481,8 +482,6 @@ int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 	return ret;
 }
 
-#endif
-
 static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
 {
 	return 1;
@@ -521,21 +520,20 @@ EXPORT_SYMBOL_GPL(page_is_ram);
 int region_intersects(resource_size_t start, size_t size, unsigned long flags,
 		      unsigned long desc)
 {
-	resource_size_t end = start + size - 1;
+	struct resource res;
 	int type = 0; int other = 0;
 	struct resource *p;
 
+	res.start = start;
+	res.end = start + size - 1;
+
 	read_lock(&resource_lock);
 	for (p = iomem_resource.child; p ; p = p->sibling) {
 		bool is_type = (((p->flags & flags) == flags) &&
 				((desc == IORES_DESC_NONE) ||
 				 (desc == p->desc)));
 
-		if (start >= p->start && start <= p->end)
-			is_type ? type++ : other++;
-		if (end >= p->start && end <= p->end)
-			is_type ? type++ : other++;
-		if (p->start >= start && p->end <= end)
+		if (resource_overlaps(p, &res))
 			is_type ? type++ : other++;
 	}
 	read_unlock(&resource_lock);
@@ -1132,6 +1130,15 @@ struct resource * __request_region(struct resource *parent,
 		conflict = __request_resource(parent, res);
 		if (!conflict)
 			break;
+		/*
+		 * mm/hmm.c reserves physical addresses which then
+		 * become unavailable to other users.  Conflicts are
+		 * not expected.  Warn to aid debugging if encountered.
+		 */
+		if (conflict->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) {
+			pr_warn("Unaddressable device %s %pR conflicts with %pR",
+				conflict->name, conflict, res);
+		}
 		if (conflict != parent) {
 			if (!(conflict->flags & IORESOURCE_BUSY)) {
 				parent = conflict;