mm/cma.c: switch to bitmap_zalloc() for cma bitmap allocation

kzalloc() is used for cma bitmap allocation in cma_activate_area(),
switch to bitmap_zalloc() for clarity.

Link: http://lkml.kernel.org/r/895d4627-f115-c77a-d454-c0a196116426@huawei.comSigned-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Yue Hu <huyue2@yulong.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Ryohei Suzuki <ryh.szk.cmnty@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Doug Berger <opendmb@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/cma.c

@@ -95,13 +95,11 @@ static void cma_clear_bitmap(struct cma *cma, unsigned long pfn,
 
 static int __init cma_activate_area(struct cma *cma)
 {
-	int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long);
 	unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
 	unsigned i = cma->count >> pageblock_order;
 	struct zone *zone;
 
-	cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
-
+	cma->bitmap = bitmap_zalloc(cma_bitmap_maxno(cma), GFP_KERNEL);
 	if (!cma->bitmap) {
 		cma->count = 0;
 		return -ENOMEM;
@@ -139,7 +137,7 @@ static int __init cma_activate_area(struct cma *cma)
 
 not_in_zone:
 	pr_err("CMA area %s could not be activated\n", cma->name);
-	kfree(cma->bitmap);
+	bitmap_free(cma->bitmap);
 	cma->count = 0;
 	return -EINVAL;
 }