[PATCH 4/9] mm/compaction: simplify pfn iteration in isolate_freepages_range

[Kemeng Shi]

We call isolate_freepages_block in strict mode, continuous pages in
pageblock will be isolated if isolate_freepages_block successed.
Then pfn + isolated will point to start of next pageblock to scan
no matter how many pageblocks are isolated in isolate_freepages_block.
Use pfn + isolated as start of next pageblock to scan to simplify the
iteration.

Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
---
 mm/compaction.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 684f6e6cd8bc..8d7d38073d30 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -733,21 +733,11 @@ isolate_freepages_range(struct compact_control *cc,
 	block_end_pfn = pageblock_end_pfn(pfn);
 
 	for (; pfn < end_pfn; pfn += isolated,
-				block_start_pfn = block_end_pfn,
-				block_end_pfn += pageblock_nr_pages) {
+				block_start_pfn = pfn,
+				block_end_pfn = pfn + pageblock_nr_pages) {
 		/* Protect pfn from changing by isolate_freepages_block */
 		unsigned long isolate_start_pfn = pfn;
 
-		/*
-		 * pfn could pass the block_end_pfn if isolated freepage
-		 * is more than pageblock order. In this case, we adjust
-		 * scanning range to right one.
-		 */
-		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);
 
 		if (!pageblock_pfn_to_page(block_start_pfn,
-- 
2.30.0