mm/compaction: merge end_pfn boundary check in isolate_freepages_range

Merge the end_pfn boundary check for single page block forward and
multiple page blocks forward to avoid do twice boundary check for multiple
page blocks forward.

Link: https://lkml.kernel.org/r/20230803094901.2915942-3-shikemeng@huaweicloud.comSigned-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/compaction.c

@@ -740,8 +740,6 @@ isolate_freepages_range(struct compact_control *cc,
 		/* Protect pfn from changing by isolate_freepages_block */
 		unsigned long isolate_start_pfn = pfn;
 
-		block_end_pfn = min(block_end_pfn, end_pfn);
-
 		/*
 		 * pfn could pass the block_end_pfn if isolated freepage
 		 * is more than pageblock order. In this case, we adjust
@@ -750,9 +748,10 @@ isolate_freepages_range(struct compact_control *cc,
 		if (pfn >= block_end_pfn) {
 			block_start_pfn = pageblock_start_pfn(pfn);
 			block_end_pfn = pageblock_end_pfn(pfn);
-			block_end_pfn = min(block_end_pfn, end_pfn);
 		}
 
+		block_end_pfn = min(block_end_pfn, end_pfn);
+
 		if (!pageblock_pfn_to_page(block_start_pfn,
 					block_end_pfn, cc->zone))
 			break;