mm/page_counter: use page_counter_read in page_counter_set_max

Use page_counter_read() in page_counter_set_max().

Link: https://lkml.kernel.org/r/20201113141048.GA178922@rlkSigned-off-by: Hui Su <sh_def@163.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@cloud.ionos.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_counter.c

@@ -183,14 +183,14 @@ int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages)
 		 * the limit, so if it sees the old limit, we see the
 		 * modified counter and retry.
 		 */
-		usage = atomic_long_read(&counter->usage);
+		usage = page_counter_read(counter);
 
 		if (usage > nr_pages)
 			return -EBUSY;
 
 		old = xchg(&counter->max, nr_pages);
 
-		if (atomic_long_read(&counter->usage) <= usage)
+		if (page_counter_read(counter) <= usage)
 			return 0;
 
 		counter->max = old;