Thread (10 messages) 10 messages, 3 authors, 2012-08-24

Re: Fixup the page of buddy_higher address's calculation

From: Michal Hocko <hidden>
Date: 2012-08-23 09:50:27
Also in: lkml

On Thu 23-08-12 16:40:13, Li Haifeng wrote:
From d7cd78f9d71a5c9ddeed02724558096f0bb4508a Mon Sep 17 00:00:00 2001
From: Haifeng Li <redacted>
Date: Thu, 23 Aug 2012 16:27:19 +0800
Subject: [PATCH] Fixup the page of buddy_higher address's calculation
Some general questions:
Any word about the change? Is it really that obvious? Why do you think the
current state is incorrect? How did you find out?

And more specific below:
quoted hunk ↗ jump to hunk
Signed-off-by: Haifeng Li <redacted>
---
 mm/page_alloc.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ddbc17d..5588f68 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -579,7 +579,7 @@ static inline void __free_one_page(struct page *page,
                combined_idx = buddy_idx & page_idx;
                higher_page = page + (combined_idx - page_idx);
                buddy_idx = __find_buddy_index(combined_idx, order + 1);
-               higher_buddy = page + (buddy_idx - combined_idx);
+               higher_buddy = page + (buddy_idx - page_idx);
We are finding buddy index for combined_idx so why should we use
page_idx here?
                if (page_is_buddy(higher_page, higher_buddy, order + 1)) {
                        list_add_tail(&page->lru,
                                &zone->free_area[order].free_list[migratetype]);
--
1.7.5.4
-- 
Michal Hocko
SUSE Labs

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