mm/madvise.c: replace with page_size() in madvise_inject_error()

page_size() is supported after the commit a50b854e ("mm: introduce
page_size()").

Use page_size() in madvise_inject_error() for readability.

[akpm@linux-foundation.org: use ulong for `size', per David]
Link: http://lkml.kernel.org/r/29dce60c-38d6-0220-f292-e298f0c78c4d@huawei.comSigned-off-by: NYunfeng Ye <yeyunfeng@huawei.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Hu Shiyuan <hushiyuan@huawei.com>
Cc: Feilong Lin <linfeilong@huawei.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/madvise.c

@@ -864,13 +864,13 @@ static int madvise_inject_error(int behavior,
 {
 	struct page *page;
 	struct zone *zone;
-	unsigned int order;
+	unsigned long size;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
 
-	for (; start < end; start += PAGE_SIZE << order) {
+	for (; start < end; start += size) {
 		unsigned long pfn;
 		int ret;
 
@@ -882,9 +882,9 @@ static int madvise_inject_error(int behavior,
 		/*
 		 * When soft offlining hugepages, after migrating the page
 		 * we dissolve it, therefore in the second loop "page" will
-		 * no longer be a compound page, and order will be 0.
+		 * no longer be a compound page.
 		 */
-		order = compound_order(compound_head(page));
+		size = page_size(compound_head(page));
 
 		if (PageHWPoison(page)) {
 			put_page(page);