mm/page_alloc.c: __perform_reclaim should return 'unsigned long'

__perform_reclaim()'s single caller expects it to return 'unsigned long',
hence change its return value and a local variable to 'unsigned long'.
Suggested-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NYanfei Xu <yanfei.xu@windriver.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20200916022138.16740-1-yanfei.xu@windriver.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -4253,13 +4253,12 @@ EXPORT_SYMBOL_GPL(fs_reclaim_release);
 #endif
 
 /* Perform direct synchronous page reclaim */
-static int
+static unsigned long
 __perform_reclaim(gfp_t gfp_mask, unsigned int order,
 					const struct alloc_context *ac)
 {
-	int progress;
 	unsigned int noreclaim_flag;
-	unsigned long pflags;
+	unsigned long pflags, progress;
 
 	cond_resched();