[PATCH] vmalloc: optimization, cleanup, bugfixes
Eric Dumazet [Fri, 10 Nov 2006 20:27:48 +0000 (12:27 -0800)]
- 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>

include/linux/vmalloc.h
mm/vmalloc.c

index dc9a29d..924e502 100644 (file)
@@ -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;
 };
 
 /*
index 46606c1..7dc6aa7 100644 (file)
@@ -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);