diff --git a/kernel/memremap.c b/kernel/memremap.c
index e517a16cb426..cbc3e97e2bb4 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -183,7 +183,11 @@ EXPORT_SYMBOL(put_zone_device_page);
 
 static void pgmap_radix_release(struct resource *res)
 {
-	resource_size_t key;
+	resource_size_t key, align_start, align_size, align_end;
+
+	align_start = res->start & ~(SECTION_SIZE - 1);
+	align_size = ALIGN(resource_size(res), SECTION_SIZE);
+	align_end = align_start + align_size - 1;
 
 	mutex_lock(&pgmap_lock);
 	for (key = res->start; key <= res->end; key += SECTION_SIZE)
@@ -226,12 +230,11 @@ static void devm_memremap_pages_release(struct device *dev, void *data)
 		percpu_ref_put(pgmap->ref);
 	}
 
-	pgmap_radix_release(res);
-
 	/* pages are dead and unused, undo the arch mapping */
 	align_start = res->start & ~(SECTION_SIZE - 1);
 	align_size = ALIGN(resource_size(res), SECTION_SIZE);
 	arch_remove_memory(align_start, align_size);
+	pgmap_radix_release(res);
 	dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
 			"%s: failed to free all reserved pages\n", __func__);
 }
@@ -267,7 +270,7 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
 {
 	int is_ram = region_intersects(res->start, resource_size(res),
 			"System RAM");
-	resource_size_t key, align_start, align_size;
+	resource_size_t key, align_start, align_size, align_end;
 	struct dev_pagemap *pgmap;
 	struct page_map *page_map;
 	unsigned long pfn;
@@ -309,7 +312,10 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
 
 	mutex_lock(&pgmap_lock);
 	error = 0;
-	for (key = res->start; key <= res->end; key += SECTION_SIZE) {
+	align_start = res->start & ~(SECTION_SIZE - 1);
+	align_size = ALIGN(resource_size(res), SECTION_SIZE);
+	align_end = align_start + align_size - 1;
+	for (key = align_start; key <= align_end; key += SECTION_SIZE) {
 		struct dev_pagemap *dup;
 
 		rcu_read_lock();
@@ -336,8 +342,6 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
 	if (nid < 0)
 		nid = numa_mem_id();
 
-	align_start = res->start & ~(SECTION_SIZE - 1);
-	align_size = ALIGN(resource_size(res), SECTION_SIZE);
 	error = arch_add_memory(nid, align_start, align_size, true);
 	if (error)
 		goto err_add_memory;