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Date: Tue, 20 Mar 2018 21:50:20 +0800
From: Aaron Lu <aaron.lu@...el.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
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 Tue, Mar 20, 2018 at 12:35:46PM +0100, Vlastimil Babka wrote:
> 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
An right, forgot to remove it...
>
> Acked-by: Vlastimil Babka <vbabka@...e.cz>
Thanks!
>
> > +}
> > +
> > +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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