[PATCH] vmalloc: optimization, cleanup, bugfixes

- reorder 'struct vm_struct' to speedup lookups on CPUS with small cache
  lines.  The fields 'next,addr,size' should be now in the same cache line,
  to speedup lookups.

- One minor cleanup in __get_vm_area_node()

- Bugfixes in vmalloc_user() and vmalloc_32_user() NULL returns from
  __vmalloc() and __find_vm_area() were not tested.

[akpm@osdl.org: remove redundant BUG_ONs]
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

include/linux/vmalloc.h

@@ -23,13 +23,14 @@ struct vm_area_struct;
 #endif
 
 struct vm_struct {
+	/* keep next,addr,size together to speedup lookups */
+	struct vm_struct	*next;
 	void			*addr;
 	unsigned long		size;
 	unsigned long		flags;
 	struct page		**pages;
 	unsigned int		nr_pages;
 	unsigned long		phys_addr;
-	struct vm_struct	*next;
 };
 
 /*

mm/vmalloc.c

@@ -186,10 +186,8 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, unsigned long fl
 	if (unlikely(!area))
 		return NULL;
 
-	if (unlikely(!size)) {
-		kfree (area);
+	if (unlikely(!size))
 		return NULL;
-	}
 
 	/*
 	 * We always allocate a guard page.
@@ -532,11 +530,12 @@ void *vmalloc_user(unsigned long size)
 	void *ret;
 
 	ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
-	write_lock(&vmlist_lock);
-	area = __find_vm_area(ret);
-	area->flags |= VM_USERMAP;
-	write_unlock(&vmlist_lock);
-
+	if (ret) {
+		write_lock(&vmlist_lock);
+		area = __find_vm_area(ret);
+		area->flags |= VM_USERMAP;
+		write_unlock(&vmlist_lock);
+	}
 	return ret;
 }
 EXPORT_SYMBOL(vmalloc_user);
@@ -605,11 +604,12 @@ void *vmalloc_32_user(unsigned long size)
 	void *ret;
 
 	ret = __vmalloc(size, GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL);
-	write_lock(&vmlist_lock);
-	area = __find_vm_area(ret);
-	area->flags |= VM_USERMAP;
-	write_unlock(&vmlist_lock);
-
+	if (ret) {
+		write_lock(&vmlist_lock);
+		area = __find_vm_area(ret);
+		area->flags |= VM_USERMAP;
+		write_unlock(&vmlist_lock);
+	}
 	return ret;
 }
 EXPORT_SYMBOL(vmalloc_32_user);