mm, vmalloc: only call setup_vmalloc_vm() only in __get_vm_area_node()

Now for insert_vmalloc_vm, it only calls the two functions:

 - setup_vmalloc_vm: fill vm_struct and vmap_area instances
 - clear_vm_unlist: clear VM_UNLIST bit in vm_struct->flags

So in __get_vm_area_node(), if VM_UNLIST bit unset in flags, that is the
else branch here, we don't need to clear VM_UNLIST bit for vm->flags since
this bit is obviously not set.  That is to say, we could only call
setup_vmalloc_vm instead of insert_vmalloc_vm here.  And then we could
even remove the if test here.
Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/vmalloc.c

@@ -1367,16 +1367,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size,
 		return NULL;
 	}
 
-	/*
-	 * When this function is called from __vmalloc_node_range,
-	 * we add VM_UNLIST flag to avoid accessing uninitialized
-	 * members of vm_struct such as pages and nr_pages fields.
-	 * They will be set later.
-	 */
-	if (flags & VM_UNLIST)
 	setup_vmalloc_vm(area, va, flags, caller);
-	else
-		insert_vmalloc_vm(area, va, flags, caller);
 
 	return area;
 }