linux-kernel - [PATCH] mm/page_isolation: unset migratetype directly for non Buddy page

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Date:   Wed, 29 Dec 2021 11:36:49 +0800
From:   Chen Wandun <chenwandun@...wei.com>
To:     <akpm@...ux-foundation.org>, <vbabka@...e.cz>,
        <iamjoonsoo.kim@....com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>
CC:     <wangkefeng.wang@...wei.com>
Subject: [PATCH] mm/page_isolation: unset migratetype directly for non Buddy page

There is no need to try to move_freepages_block for pages that is not
in buddy in function unset_migratetype_isolate, it can directly set
migrate type.

It will save a few cpu cycles for some situations such as cma and
hugetlb when allocating continue pages, in these situation function
alloc_contig_pages will be called.

alloc_contig_pages
	__alloc_contig_migrate_range
	isolate_freepages_range ==> pages has been remove from buddy
	undo_isolate_page_range
		unset_migratetype_isolate ==> can directly set migratetype

Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock")
Signed-off-by: Chen Wandun <chenwandun@...wei.com>
---
 mm/page_isolation.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index f67c4c70f17f..6a0ddda6b3c5 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -115,7 +115,7 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
 	 * onlining - just onlined memory won't immediately be considered for
 	 * allocation.
 	 */
-	if (!isolated_page) {
+	if (!isolated_page && PageBuddy(page)) {
 		nr_pages = move_freepages_block(zone, page, migratetype, NULL);
 		__mod_zone_freepage_state(zone, nr_pages, migratetype);
 	}
-- 
2.18.0.huawei.25