linux-kernel - [PATCH 11/12] mm: compaction: simplify the code in __compact

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Message-ID: <20220418141253.24298-12-linmiaohe@huawei.com>
Date:   Mon, 18 Apr 2022 22:12:52 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <vbabka@...e.cz>, <pintu@...eaurora.org>,
        <charante@...eaurora.org>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linmiaohe@...wei.com>
Subject: [PATCH 11/12] mm: compaction: simplify the code in __compact_finished

Since commit efe771c7603b ("mm, compaction: always finish scanning of a
full pageblock"), compaction will always finish scanning a pageblock. And
migrate_pfn is assured to align with pageblock_nr_pages when we reach here.
So we will always return COMPACT_SUCCESS if a suitable fallback is found
due to the below IS_ALIGNED check of migrate_pfn. Simplify the code to make
this clear and improve the readability. No functional change intended.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/compaction.c | 29 ++++++++---------------------
 1 file changed, 8 insertions(+), 21 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 334a573485fe..609a76d7e051 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2134,29 +2134,16 @@ static enum compact_result __compact_finished(struct compact_control *cc)
 		 * other migratetype buddy lists.
 		 */
 		if (find_suitable_fallback(area, order, migratetype,
-						true, &can_steal) != -1) {
-
-			/* movable pages are OK in any pageblock */
-			if (migratetype == MIGRATE_MOVABLE)
-				return COMPACT_SUCCESS;
-
+						true, &can_steal) != -1)
 			/*
-			 * We are stealing for a non-movable allocation. Make
-			 * sure we finish compacting the current pageblock
-			 * first so it is as free as possible and we won't
-			 * have to steal another one soon. This only applies
-			 * to sync compaction, as async compaction operates
-			 * on pageblocks of the same migratetype.
+			 * Movable pages are OK in any pageblock. If we are
+			 * stealing for a non-movable allocation, make sure
+			 * we finish compacting the current pageblock first
+			 * (which is assured by the above migrate_pfn align
+			 * check) so it is as free as possible and we won't
+			 * have to steal another one soon.
 			 */
-			if (cc->mode == MIGRATE_ASYNC ||
-					IS_ALIGNED(cc->migrate_pfn,
-							pageblock_nr_pages)) {
-				return COMPACT_SUCCESS;
-			}
-
-			ret = COMPACT_CONTINUE;
-			break;
-		}
+			return COMPACT_SUCCESS;
 	}
 
 out:
-- 
2.23.0