alloc_vmap_area: fix memory leak

If alloc_vmap_area() fails the allocated struct vmap_area has to be freed.
Signed-off-by: Ralph Wuerthner <ralphw@linux.vnet.ibm.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/vmalloc.c

@@ -402,6 +402,7 @@ overflow:
 			printk(KERN_WARNING
 				"vmap allocation for size %lu failed: "
 				"use vmalloc=<size> to increase size.\n", size);
+		kfree(va);
 		return ERR_PTR(-EBUSY);
 	}