linux-kernel - [PATCH v2 1/2] mm/page_alloc: remove unnecessary check in break_down_buddy

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Date:   Wed, 27 Sep 2023 18:35:13 +0800
From:   Kemeng Shi <shikemeng@...weicloud.com>
To:     akpm@...ux-foundation.org, naoya.horiguchi@....com,
        osalvador@...e.de, willy@...radead.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/2] mm/page_alloc: remove unnecessary check in break_down_buddy_pages

1. We always have target in range started with next_page and full free
range started with current_buddy.
2. The last split range size is 1 << low and low should be >= 0, then
size >= 1. So page + size != page is always true (because size > 0).
As summary, current_page will not equal to target page.

Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@....com>
---
 mm/page_alloc.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e18e0e20eff8..bad979493dde 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6696,10 +6696,8 @@ static void break_down_buddy_pages(struct zone *zone, struct page *page,
 		if (set_page_guard(zone, current_buddy, high, migratetype))
 			continue;
 
-		if (current_buddy != target) {
-			add_to_free_list(current_buddy, zone, high, migratetype);
-			set_buddy_order(current_buddy, high);
-		}
+		add_to_free_list(current_buddy, zone, high, migratetype);
+		set_buddy_order(current_buddy, high);
 	}
 }
 
-- 
2.30.0