hugetlb: add phys addr to struct huge_bootmem_page

This is needed on HIGHMEM systems - we don't always have a virtual
address so store the physical address and map it in as needed.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/hugetlb.h

@@ -231,6 +231,9 @@ struct hstate {
 struct huge_bootmem_page {
 	struct list_head list;
 	struct hstate *hstate;
+#ifdef CONFIG_HIGHMEM
+	phys_addr_t phys;
+#endif
 };
 
 struct page *alloc_huge_page_node(struct hstate *h, int nid);

mm/hugetlb.c

@@ -1105,8 +1105,16 @@ static void __init gather_bootmem_prealloc(void)
 	struct huge_bootmem_page *m;
 
 	list_for_each_entry(m, &huge_boot_pages, list) {
-		struct page *page = virt_to_page(m);
 		struct hstate *h = m->hstate;
+		struct page *page;
+
+#ifdef CONFIG_HIGHMEM
+		page = pfn_to_page(m->phys >> PAGE_SHIFT);
+		free_bootmem_late((unsigned long)m,
+				  sizeof(struct huge_bootmem_page));
+#else
+		page = virt_to_page(m);
+#endif
 		__ClearPageReserved(page);
 		WARN_ON(page_count(page) != 1);
 		prep_compound_huge_page(page, h->order);