Virtual Compound Pages: vmalloc compound support


---
 mm/vmalloc.c |   40 ++++++++++++++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 8 deletions(-)

Index: linux-2.6/mm/vmalloc.c
===================================================================
--- linux-2.6.orig/mm/vmalloc.c	2007-09-15 20:33:01.000000000 -0700
+++ linux-2.6/mm/vmalloc.c	2007-09-15 20:40:49.000000000 -0700
@@ -169,7 +169,7 @@ EXPORT_SYMBOL_GPL(map_vm_area);
 /*
  * Map a vmalloc()-space virtual address to the physical page.
  */
-struct page *vmalloc_to_page(void *vmalloc_addr)
+struct page *vmalloc_to_page(const void *vmalloc_addr)
 {
 	unsigned long addr = (unsigned long) vmalloc_addr;
 	struct page *page = NULL;
@@ -403,10 +403,24 @@ static void __vunmap(void *addr, int dea
 
 	if (deallocate_pages) {
 		int i;
+		int comp = PageCompound(area->pages[0]);
 
 		for (i = 0; i < area->nr_pages; i++) {
-			BUG_ON(!area->pages[i]);
-			__free_page(area->pages[i]);
+			struct page *page = area->pages[i];
+
+			BUG_ON(!page);
+			if (comp) {
+				if (i) {
+					BUG_ON(page->first_page != area->pages[0] ||
+						PageHead(page) || !PageTail(page));
+					__ClearPageTail(page);
+				}
+				else {
+					BUG_ON(PageTail(page) || !PageHead(page));
+					__ClearPageHead(page);
+				}
+			}
+			__free_page(page);
 		}
 
 		if (area->flags & VM_VPAGES)
@@ -527,16 +541,26 @@ void *__vmalloc_area_node(struct vm_stru
 		return NULL;
 	}
 
+	if (nr_pages < 2)
+		gfp_mask &= ~__GFP_COMP;
+
 	for (i = 0; i < area->nr_pages; i++) {
-		if (node < 0)
-			area->pages[i] = alloc_page(gfp_mask);
-		else
-			area->pages[i] = alloc_pages_node(node, gfp_mask, 0);
-		if (unlikely(!area->pages[i])) {
+		struct page * page = alloc_pages_node(node, gfp_mask, 0);
+
+		if (unlikely(!page)) {
 			/* Successfully allocated i pages, free them in __vunmap() */
 			area->nr_pages = i;
 			goto fail;
 		}
+		if (gfp_mask & __GFP_COMP) {
+			if (i) {
+				__SetPageTail(page);
+				page->first_page = area->pages[0];
+			} else {
+				__SetPageHead(page);
+			}
+		}
+		area->pages[i] = page;
 	}
 
 	if (map_vm_area(area, prot, &pages))