diff --git a/mm/memory.c b/mm/memory.c
index ed64455c73bd..34e60a5baf7c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -7129,6 +7129,7 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
 	resource_size_t phys_addr;
 	pgprot_t prot = __pgprot(0);
 	void __iomem *maddr;
+	struct page *page;
 	int offset = offset_in_page(addr);
 	int ret = -EINVAL;
 	bool writable;
@@ -7143,6 +7144,19 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
 retry:
 	if (follow_pfnmap_start(&args))
 		return -EINVAL;
+
+	/*
+	 * Reject anything that looks like ordinary RAM, including anonymous
+	 * folios in CoW mappings or allocated kernel memory. Note that we
+	 * cannot distinguish memblock allocations from non-RAM reliably, so
+	 * we cannot easily reject them here.
+	 */
+	page = pfn_to_online_page(args.pfn);
+	if (page && !PageReserved(page)) {
+		follow_pfnmap_end(&args);
+		return -EINVAL;
+	}
+
 	prot = args.pgprot;
 	phys_addr = (resource_size_t)args.pfn << PAGE_SHIFT;
 	writable = args.writable;