1 files changed, 7 insertions, 4 deletions

diff --git a/mm/memremap.c b/mm/memremap.c
index 68204912cc0a..03ccbdfeb697 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -103,6 +103,7 @@ static void dev_pagemap_cleanup(struct dev_pagemap *pgmap)
 void memunmap_pages(struct dev_pagemap *pgmap)
 {
         struct resource *res = &pgmap->res;
+        struct page *first_page;
         unsigned long pfn;
         int nid;
 
@@ -111,14 +112,16 @@ void memunmap_pages(struct dev_pagemap *pgmap)
                 put_page(pfn_to_page(pfn));
         dev_pagemap_cleanup(pgmap);
 
+        /* make sure to access a memmap that was actually initialized */
+        first_page = pfn_to_page(pfn_first(pgmap));
+
         /* pages are dead and unused, undo the arch mapping */
-        nid = page_to_nid(pfn_to_page(PHYS_PFN(res->start)));
+        nid = page_to_nid(first_page);
 
         mem_hotplug_begin();
         if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
-                pfn = PHYS_PFN(res->start);
-                __remove_pages(page_zone(pfn_to_page(pfn)), pfn,
-                                 PHYS_PFN(resource_size(res)), NULL);
+                __remove_pages(page_zone(first_page), PHYS_PFN(res->start),
+                               PHYS_PFN(resource_size(res)), NULL);
         } else {
                 arch_remove_memory(nid, res->start, resource_size(res),
                                 pgmap_altmap(pgmap));