[PATCH] dup_mmap() double memory accounting

dup_mmap() unnecessarily tries to account for memory of the vma's it has
created if it fails in the middle.

However, that's pointless (and wrong), since the exit_mmap() path called
through mmput() will do so anyway in the failure path.

Just remove the bogus un-accounting code.

kernel/fork.c

@@ -271,7 +271,6 @@ static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
 	struct vm_area_struct * mpnt, *tmp, **pprev;
 	struct rb_node **rb_link, *rb_parent;
 	int retval;
-	unsigned long charge = 0;
 	struct mempolicy *pol;
 
 	down_write(&oldmm->mmap_sem);
@@ -308,7 +307,6 @@ static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
 			unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
 			if (security_vm_enough_memory(len))
 				goto fail_nomem;
-			charge += len;
 		}
 		tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 		if (!tmp)
@@ -360,7 +358,7 @@ static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
 			tmp->vm_ops->open(tmp);
 
 		if (retval)
-			goto fail;
+			goto out;
 	}
 	retval = 0;
 
@@ -372,8 +370,6 @@ static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
 	kmem_cache_free(vm_area_cachep, tmp);
 fail_nomem:
 	retval = -ENOMEM;
-fail:
-	vm_unacct_memory(charge);
 	goto out;
 }
 static inline int mm_alloc_pgd(struct mm_struct * mm)