[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: Eric Dumazet <dada1@cosmosbay.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 15 insertions, 14 deletions

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index dc9a29d84abc..924e502905d4 100644
--- a/include/linux/vmalloc.h
+++ b/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;
 };
 
 /*
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 46606c133e82..7dc6aa745166 100644
--- a/mm/vmalloc.c
+++ b/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);