From: Li Haifeng <[email protected]>
Subject: mm/page_alloc: fix the page address of higher page's buddy calculation
The heuristic method for buddy has been introduced since 43506fad
("mm/page_alloc.c: simplify calculation of combined index of adjacent
buddy lists"). But the page address of higher page's buddy was wrongly
calculated, which will lead page_is_buddy to fail for ever. IOW, the
heuristic method would be disabled with the wrong page address of higher
page's buddy.
Calculating the page address of higher page's buddy should be based
higher_page with the offset between index of higher page and index of
higher page's buddy.
Signed-off-by: Haifeng Li <[email protected]>
Signed-off-by: Gavin Shan <[email protected]>
Reviewed-by: Michal Hocko <[email protected]>
Cc: KyongHo Cho <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: <[email protected]> [2.6.38+]
Signed-off-by: Andrew Morton <[email protected]>
---
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN
mm/page_alloc.c~mm-page_alloc-fix-the-page-address-of-higher-pages-buddy-calculation
mm/page_alloc.c
---
a/mm/page_alloc.c~mm-page_alloc-fix-the-page-address-of-higher-pages-buddy-calculation
+++ a/mm/page_alloc.c
@@ -584,7 +584,7 @@ static inline void __free_one_page(struc
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 = higher_page + (buddy_idx - combined_idx);
if (page_is_buddy(higher_page, higher_buddy, order + 1)) {
list_add_tail(&page->lru,
&zone->free_area[order].free_list[migratetype]);
_
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