linux-kernel - [PATCH v3 4/8] mm/compaction: correct comment of fast_find_migrateblock in isolate

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Message-Id: <20230804110454.2935878-5-shikemeng@huaweicloud.com>
Date:   Fri,  4 Aug 2023 19:04:50 +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 v3 4/8] mm/compaction: correct comment of fast_find_migrateblock in isolate_migratepages

After 90ed667c03fe5 ("Revert "Revert "mm/compaction: fix set skip in
fast_find_migrateblock"""), we remove skip set in fast_find_migrateblock.
Correct comment that fast_find_block is used to avoid isolation_suitable
check for pageblock returned from fast_find_migrateblock because
fast_find_migrateblock will mark found pageblock skipped.
Instead, comment that fast_find_block is used to avoid a redundant check
of fast found pageblock which is already checked skip flag inside
fast_find_migrateblock.

Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
---
 mm/compaction.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 9a2f0bd5394a..4bf2dc936add 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1988,9 +1988,9 @@ static isolate_migrate_t isolate_migratepages(struct compact_control *cc)
 		block_start_pfn = cc->zone->zone_start_pfn;
 
 	/*
-	 * fast_find_migrateblock marks a pageblock skipped so to avoid
-	 * the isolation_suitable check below, check whether the fast
-	 * search was successful.
+	 * fast_find_migrateblock() has already ensured the pageblock is not
+	 * set with a skipped flag, so to avoid the isolation_suitable check
+	 * below again, check whether the fast search was successful.
 	 */
 	fast_find_block = low_pfn != cc->migrate_pfn && !cc->fast_search_fail;
 
-- 
2.30.0