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Date: Tue, 20 Mar 2018 12:35:46 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Aaron Lu <aaron.lu@...el.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Huang Ying <ying.huang@...el.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Kemi Wang <kemi.wang@...el.com>,
Tim Chen <tim.c.chen@...ux.intel.com>,
Andi Kleen <ak@...ux.intel.com>,
Michal Hocko <mhocko@...e.com>,
Mel Gorman <mgorman@...hsingularity.net>,
Matthew Wilcox <willy@...radead.org>,
Daniel Jordan <daniel.m.jordan@...cle.com>
Subject: Re: [RFC PATCH v2 1/4] mm/page_alloc: use helper functions to
add/remove a page to/from buddy
On 03/20/2018 09:54 AM, Aaron Lu wrote:
> 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.
>
> Signed-off-by: Aaron Lu <aaron.lu@...el.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 3db9cfb2265b..3cdf1e10d412 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -736,12 +736,41 @@ 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, int mt)
> +{
> + set_page_order(page, order);
> + zone->free_area[order].nr_free++;
The 'mt' parameter seems unused here. Otherwise
Acked-by: Vlastimil Babka <vbabka@...e.cz>
> +}
> +
> +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, mt);
> + 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, mt);
> + 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 do coalesce a page and its buddy if
> @@ -845,13 +874,10 @@ 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;
> @@ -883,8 +909,6 @@ 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
> @@ -901,15 +925,12 @@ 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);
> }
>
> /*
> @@ -1731,9 +1752,7 @@ 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);
> }
> }
>
> @@ -1877,9 +1896,7 @@ 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;
> @@ -2795,9 +2812,7 @@ 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
> @@ -7886,9 +7901,7 @@ __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);
>
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