linux-kernel - [PATCH v2 3/4] mm/compaction: remove unnecessary cursor page in isolate_freepages

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Message-Id: <20230803094901.2915942-4-shikemeng@huaweicloud.com>
Date:   Thu,  3 Aug 2023 17:49:00 +0800
From:   Kemeng Shi <shikemeng@...weicloud.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, baolin.wang@...ux.alibaba.com,
        mgorman@...hsingularity.net, david@...hat.com
Cc:     shikemeng@...weicloud.com
Subject: [PATCH v2 3/4] mm/compaction: remove unnecessary cursor page in isolate_freepages_block

The cursor is only used for page forward currently. We can simply move page
forward directly to remove unnecessary cursor.

Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
---
 mm/compaction.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index b7a05b9843ed..cb1dd5c5bf3f 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -584,7 +584,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 				bool strict)
 {
 	int nr_scanned = 0, total_isolated = 0;
-	struct page *cursor;
+	struct page *page;
 	unsigned long flags = 0;
 	bool locked = false;
 	unsigned long blockpfn = *start_pfn;
@@ -594,12 +594,11 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 	if (strict)
 		stride = 1;
 
-	cursor = pfn_to_page(blockpfn);
+	page = pfn_to_page(blockpfn);
 
 	/* Isolate free pages. */
-	for (; blockpfn < end_pfn; blockpfn += stride, cursor += stride) {
+	for (; blockpfn < end_pfn; blockpfn += stride, page += stride) {
 		int isolated;
-		struct page *page = cursor;
 
 		/*
 		 * Periodically drop the lock (if held) regardless of its
@@ -624,7 +623,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 
 			if (likely(order <= MAX_ORDER)) {
 				blockpfn += (1UL << order) - 1;
-				cursor += (1UL << order) - 1;
+				page += (1UL << order) - 1;
 				nr_scanned += (1UL << order) - 1;
 			}
 			goto isolate_fail;
@@ -661,7 +660,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 		}
 		/* Advance to the end of split page */
 		blockpfn += isolated - 1;
-		cursor += isolated - 1;
+		page += isolated - 1;
 		continue;
 
 isolate_fail:
-- 
2.30.0