Re: [PATCH v8 4/5] mm: introduce putback_movable_pages()

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Aug 21, 2012 at 09:47:47AM -0300, Rafael Aquini wrote:
> The PATCH "mm: introduce compaction and migration for virtio ballooned pages"
> hacks around putback_lru_pages() in order to allow ballooned pages to be
> re-inserted on balloon page list as if a ballooned page was like a LRU page.
> 
> As ballooned pages are not legitimate LRU pages, this patch introduces
> putback_movable_pages() to properly cope with cases where the isolated
> pageset contains ballooned pages and LRU pages, thus fixing the mentioned
> inelegant hack around putback_lru_pages().
> 
> Signed-off-by: Rafael Aquini <aquini@redhat.com>
> ---
>  include/linux/migrate.h |  2 ++
>  mm/compaction.c         |  4 ++--
>  mm/migrate.c            | 20 ++++++++++++++++++++
>  mm/page_alloc.c         |  2 +-
>  4 files changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index ce7e667..ff103a1 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -10,6 +10,7 @@ typedef struct page *new_page_t(struct page *, unsigned long private, int **);
>  #ifdef CONFIG_MIGRATION
>  
>  extern void putback_lru_pages(struct list_head *l);
> +extern void putback_movable_pages(struct list_head *l);
>  extern int migrate_page(struct address_space *,
>  			struct page *, struct page *, enum migrate_mode);
>  extern int migrate_pages(struct list_head *l, new_page_t x,
> @@ -33,6 +34,7 @@ extern int migrate_huge_page_move_mapping(struct address_space *mapping,
>  #else
>  
>  static inline void putback_lru_pages(struct list_head *l) {}
> +static inline void putback_movable_pages(struct list_head *l) {}
>  static inline int migrate_pages(struct list_head *l, new_page_t x,
>  		unsigned long private, bool offlining,
>  		enum migrate_mode mode) { return -ENOSYS; }
> diff --git a/mm/compaction.c b/mm/compaction.c
> index ce43dc2..782ed32 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -759,9 +759,9 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
>  		trace_mm_compaction_migratepages(nr_migrate - nr_remaining,
>  						nr_remaining);
>  
> -		/* Release LRU pages not migrated */
> +		/* Release isolated pages not migrated */
>  		if (err) {
> -			putback_lru_pages(&cc->migratepages);
> +			putback_movable_pages(&cc->migratepages);
>  			cc->nr_migratepages = 0;
>  			if (err == -ENOMEM) {
>  				ret = COMPACT_PARTIAL;
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 6392da258..0bf2caf 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -80,6 +80,26 @@ void putback_lru_pages(struct list_head *l)
>  		list_del(&page->lru);
>  		dec_zone_page_state(page, NR_ISOLATED_ANON +
>  				page_is_file_cache(page));
> +			putback_lru_page(page);
> +	}
> +}
> +
> +/*
> + * Put previously isolated pages back onto the appropriated lists

Do you mean appropriate lists?

> + * from where they were once taken off for compaction/migration.
> + *
> + * This function shall be used instead of putback_lru_pages(),
> + * whenever the isolated pageset has been built by isolate_migratepages_range()
> + */
> +void putback_movable_pages(struct list_head *l)
> +{
> +	struct page *page;
> +	struct page *page2;
> +
> +	list_for_each_entry_safe(page, page2, l, lru) {
> +		list_del(&page->lru);
> +		dec_zone_page_state(page, NR_ISOLATED_ANON +
> +				page_is_file_cache(page));
>  		if (unlikely(movable_balloon_page(page)))
>  			putback_balloon_page(page);
>  		else
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 009ac28..78b7663 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5669,7 +5669,7 @@ static int __alloc_contig_migrate_range(unsigned long start, unsigned long end)
>  				    0, false, MIGRATE_SYNC);
>  	}
>  
> -	putback_lru_pages(&cc.migratepages);
> +	putback_movable_pages(&cc.migratepages);
>  	return ret > 0 ? 0 : ret;
>  }
>  
> -- 
> 1.7.11.4

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