Add virt_to_head_page and consolidate code in slab and slub

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: Christoph Lameter

include/linux/mm.h

@@ -286,6 +286,12 @@ static inline void get_page(struct page *page)
 	atomic_inc(&page->_count);
 }
 
+static inline struct page *virt_to_head_page(const void *x)
+{
+	struct page *page = virt_to_page(x);
+	return compound_head(page);
+}
+
 /*
  * Setup the page count before being freed into the page allocator for
  * the first time (boot or memory hotplug)

mm/slab.c

@@ -614,20 +614,19 @@ static inline void page_set_slab(struct page *page, struct slab *slab)
 
 static inline struct slab *page_get_slab(struct page *page)
 {
-	page = compound_head(page);
 	BUG_ON(!PageSlab(page));
 	return (struct slab *)page->lru.prev;
 }
 
 static inline struct kmem_cache *virt_to_cache(const void *obj)
 {
-	struct page *page = virt_to_page(obj);
+	struct page *page = virt_to_head_page(obj);
 	return page_get_cache(page);
 }
 
 static inline struct slab *virt_to_slab(const void *obj)
 {
-	struct page *page = virt_to_page(obj);
+	struct page *page = virt_to_head_page(obj);
 	return page_get_slab(page);
 }
 
@@ -2876,7 +2875,7 @@ static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
 
 	objp -= obj_offset(cachep);
 	kfree_debugcheck(objp);
-	page = virt_to_page(objp);
+	page = virt_to_head_page(objp);
 
 	slabp = page_get_slab(page);
 
@@ -3100,7 +3099,7 @@ static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
 		struct slab *slabp;
 		unsigned objnr;
 
-		slabp = page_get_slab(virt_to_page(objp));
+		slabp = page_get_slab(virt_to_head_page(objp));
 		objnr = (unsigned)(objp - slabp->s_mem) / cachep->buffer_size;
 		slab_bufctl(slabp)[objnr] = BUFCTL_ACTIVE;
 	}

mm/slub.c

@@ -1323,9 +1323,7 @@ void kmem_cache_free(struct kmem_cache *s, void *x)
 {
 	struct page * page;
 
-	page = virt_to_page(x);
-
-	page = compound_head(page);
+	page = virt_to_head_page(x);
 
 	if (unlikely(PageError(page) && (s->flags & SLAB_STORE_USER)))
 		set_tracking(s, x, TRACK_FREE);
@@ -1336,7 +1334,7 @@ EXPORT_SYMBOL(kmem_cache_free);
 /* Figure out on which slab object the object resides */
 static struct page *get_object_page(const void *x)
 {
-	struct page *page = compound_head(virt_to_page(x));
+	struct page *page = virt_to_head_page(x);
 
 	if (!PageSlab(page))
 		return NULL;
@@ -2076,7 +2074,7 @@ void kfree(const void *x)
 	if (!x)
 		return;
 
-	page = compound_head(virt_to_page(x));
+	page = virt_to_head_page(x);
 
 	s = page->slab;
 
@@ -2112,7 +2110,7 @@ void *krealloc(const void *p, size_t new_size, gfp_t flags)
 		return NULL;
 	}
 
-	page = compound_head(virt_to_page(p));
+	page = virt_to_head_page(p);
 
 	new_cache = get_slab(new_size, flags);