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Subject[RFC v4 PATCH 1/5] mm/page_alloc: use helper functions to add/remove a page to/from buddy
Date
There are multiple places that add/remove a page into/from buddy,
introduce helper functions for them.

This also makes it easier to add code when a page is added/removed
to/from buddy.

No functionality change.

Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
---
mm/page_alloc.c | 65 +++++++++++++++++++++++++++++--------------------
1 file changed, 39 insertions(+), 26 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 89d2a2ab3fe6..14c20bb3a3da 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -697,12 +697,41 @@ static inline void set_page_order(struct page *page, unsigned int order)
__SetPageBuddy(page);
}

+static inline void add_to_buddy_common(struct page *page, struct zone *zone,
+ unsigned int order)
+{
+ set_page_order(page, order);
+ zone->free_area[order].nr_free++;
+}
+
+static inline void add_to_buddy_head(struct page *page, struct zone *zone,
+ unsigned int order, int mt)
+{
+ add_to_buddy_common(page, zone, order);
+ list_add(&page->lru, &zone->free_area[order].free_list[mt]);
+}
+
+static inline void add_to_buddy_tail(struct page *page, struct zone *zone,
+ unsigned int order, int mt)
+{
+ add_to_buddy_common(page, zone, order);
+ list_add_tail(&page->lru, &zone->free_area[order].free_list[mt]);
+}
+
static inline void rmv_page_order(struct page *page)
{
__ClearPageBuddy(page);
set_page_private(page, 0);
}

+static inline void remove_from_buddy(struct page *page, struct zone *zone,
+ unsigned int order)
+{
+ list_del(&page->lru);
+ zone->free_area[order].nr_free--;
+ rmv_page_order(page);
+}
+
/*
* This function checks whether a page is free && is the buddy
* we can coalesce a page and its buddy if
@@ -803,13 +832,10 @@ static inline void __free_one_page(struct page *page,
* Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
* merge with it and move up one order.
*/
- if (page_is_guard(buddy)) {
+ if (page_is_guard(buddy))
clear_page_guard(zone, buddy, order, migratetype);
- } else {
- list_del(&buddy->lru);
- zone->free_area[order].nr_free--;
- rmv_page_order(buddy);
- }
+ else
+ remove_from_buddy(buddy, zone, order);
combined_pfn = buddy_pfn & pfn;
page = page + (combined_pfn - pfn);
pfn = combined_pfn;
@@ -841,8 +867,6 @@ static inline void __free_one_page(struct page *page,
}

done_merging:
- set_page_order(page, order);
-
/*
* If this is not the largest possible page, check if the buddy
* of the next-highest order is free. If it is, it's possible
@@ -859,15 +883,12 @@ static inline void __free_one_page(struct page *page,
higher_buddy = higher_page + (buddy_pfn - combined_pfn);
if (pfn_valid_within(buddy_pfn) &&
page_is_buddy(higher_page, higher_buddy, order + 1)) {
- list_add_tail(&page->lru,
- &zone->free_area[order].free_list[migratetype]);
- goto out;
+ add_to_buddy_tail(page, zone, order, migratetype);
+ return;
}
}

- list_add(&page->lru, &zone->free_area[order].free_list[migratetype]);
-out:
- zone->free_area[order].nr_free++;
+ add_to_buddy_head(page, zone, order, migratetype);
}

/*
@@ -1805,9 +1826,7 @@ static inline void expand(struct zone *zone, struct page *page,
if (set_page_guard(zone, &page[size], high, migratetype))
continue;

- list_add(&page[size].lru, &area->free_list[migratetype]);
- area->nr_free++;
- set_page_order(&page[size], high);
+ add_to_buddy_head(&page[size], zone, high, migratetype);
}
}

@@ -1951,9 +1970,7 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
struct page, lru);
if (!page)
continue;
- list_del(&page->lru);
- rmv_page_order(page);
- area->nr_free--;
+ remove_from_buddy(page, zone, current_order);
expand(zone, page, order, current_order, area, migratetype);
set_pcppage_migratetype(page, migratetype);
return page;
@@ -2871,9 +2888,7 @@ int __isolate_free_page(struct page *page, unsigned int order)
}

/* Remove page from free list */
- list_del(&page->lru);
- zone->free_area[order].nr_free--;
- rmv_page_order(page);
+ remove_from_buddy(page, zone, order);

/*
* Set the pageblock if the isolated page is at least half of a
@@ -8070,9 +8085,7 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
pr_info("remove from free list %lx %d %lx\n",
pfn, 1 << order, end_pfn);
#endif
- list_del(&page->lru);
- rmv_page_order(page);
- zone->free_area[order].nr_free--;
+ remove_from_buddy(page, zone, order);
for (i = 0; i < (1 << order); i++)
SetPageReserved((page+i));
pfn += (1 << order);
--
2.17.2
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