linux-kernel - [PATCH v0] mm/page_alloc: Cleanup for __del_page_from_free

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <20250925085006.23684-1-zhongjinji@honor.com>
Date: Thu, 25 Sep 2025 16:50:06 +0800
From: zhongjinji <zhongjinji@...or.com>
To: <akpm@...ux-foundation.org>
CC: <vbabka@...e.cz>, <surenb@...gle.com>, <mhocko@...e.com>,
	<jackmanb@...gle.com>, <hannes@...xchg.org>, <ziy@...dia.com>,
	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>, <liulu.liu@...or.com>,
	<feng.han@...or.com>, <zhongjinji@...or.com>
Subject: [PATCH v0] mm/page_alloc: Cleanup for  __del_page_from_free_list()

It is unnecessary to set page->private in __del_page_from_free_list().

If the page is about to be allocated, page->private will be cleared by
post_alloc_hook() before the page is handed out. If the page is expanded
or merged, page->private will be reset by set_buddy_order, and no one
will retrieve the page's buddy_order without the PageBuddy flag being set.
If the page is isolated, it will also reset page->private when it
succeeds.

Since __del_page_from_free_list() is a hot path in the kernel, it would be
better to remove the unnecessary set_page_private().

Signed-off-by: zhongjinji <zhongjinji@...or.com>
---
 mm/page_alloc.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d1d037f97c5f..1999eb7e7c14 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -868,7 +868,6 @@ static inline void __del_page_from_free_list(struct page *page, struct zone *zon

 	list_del(&page->buddy_list);
 	__ClearPageBuddy(page);
-	set_page_private(page, 0);
 	zone->free_area[order].nr_free--;

 	if (order >= pageblock_order && !is_migrate_isolate(migratetype))
-- 
2.17.1