xen/unpopulated-alloc: consolidate pgmap manipulation

Cleanup fill_list() to keep all the pgmap manipulations in a single
location of the function.  Update the exit unwind path accordingly.

Link: http://lore.kernel.org/r/6186fa28-d123-12db-6171-a75cb6e615a5@oracle.com
Link: https://lkml.kernel.org/r/160272253442.3136502.16683842453317773487.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/xen/unpopulated-alloc.c

@@ -27,11 +27,6 @@ static int fill_list(unsigned int nr_pages)
 	if (!res)
 		return -ENOMEM;
 
-	pgmap = kzalloc(sizeof(*pgmap), GFP_KERNEL);
-	if (!pgmap)
-		goto err_pgmap;
-
-	pgmap->type = MEMORY_DEVICE_GENERIC;
 	res->name = "Xen scratch";
 	res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 
@@ -43,6 +38,11 @@ static int fill_list(unsigned int nr_pages)
 		goto err_resource;
 	}
 
+	pgmap = kzalloc(sizeof(*pgmap), GFP_KERNEL);
+	if (!pgmap)
+		goto err_pgmap;
+
+	pgmap->type = MEMORY_DEVICE_GENERIC;
 	pgmap->range = (struct range) {
 		.start = res->start,
 		.end = res->end,
@@ -92,10 +92,10 @@ static int fill_list(unsigned int nr_pages)
 	return 0;
 
 err_memremap:
-	release_resource(res);
-err_resource:
 	kfree(pgmap);
 err_pgmap:
+	release_resource(res);
+err_resource:
 	kfree(res);
 	return ret;
 }