[PATCH] mm: nommu use compound pages

Now that compound page handling is properly fixed in the VM, move nommu
over to using compound pages rather than rolling their own refcounting.

nommu vm page refcounting is broken anyway, but there is no need to have
divergent code in the core VM now, nor when it gets fixed.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: David Howells <dhowells@redhat.com>

(Needs testing, please).
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/mm/slab.c b/mm/slab.c
index f477acfb732f..ff0ab772f49d 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -590,6 +590,8 @@ static inline void page_set_cache(struct page *page, struct kmem_cache *cache)
 
 static inline struct kmem_cache *page_get_cache(struct page *page)
 {
+	if (unlikely(PageCompound(page)))
+		page = (struct page *)page_private(page);
 	return (struct kmem_cache *)page->lru.next;
 }
 
@@ -600,6 +602,8 @@ static inline void page_set_slab(struct page *page, struct slab *slab)
 
 static inline struct slab *page_get_slab(struct page *page)
 {
+	if (unlikely(PageCompound(page)))
+		page = (struct page *)page_private(page);
 	return (struct slab *)page->lru.prev;
 }
 
@@ -2412,8 +2416,11 @@ static void set_slab_attr(struct kmem_cache *cachep, struct slab *slabp,
 	struct page *page;
 
 	/* Nasty!!!!!! I hope this is OK. */
-	i = 1 << cachep->gfporder;
 	page = virt_to_page(objp);
+
+	i = 1;
+	if (likely(!PageCompound(page)))
+		i <<= cachep->gfporder;
 	do {
 		page_set_cache(page, cachep);
 		page_set_slab(page, slabp);