linux-kernel - Re: [PATCH v5 02/12] mm: migrate: support non-lru movable page migration

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Message-ID: <20160516070455.GA28813@swordfish>
Date:	Mon, 16 May 2016 16:04:55 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Minchan Kim <minchan@...nel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Rik van Riel <riel@...hat.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Mel Gorman <mgorman@...e.de>, Hugh Dickins <hughd@...gle.com>,
	Rafael Aquini <aquini@...hat.com>,
	virtualization@...ts.linux-foundation.org,
	Jonathan Corbet <corbet@....net>,
	John Einar Reitan <john.reitan@...s.arm.com>,
	dri-devel@...ts.freedesktop.org,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Gioh Kim <gi-oh.kim@...fitbricks.com>
Subject: Re: [PATCH v5 02/12] mm: migrate: support non-lru movable page
 migration

On (05/09/16 11:20), Minchan Kim wrote:
> +++ b/include/linux/migrate.h
> @@ -32,11 +32,16 @@ extern char *migrate_reason_names[MR_TYPES];
>  
>  #ifdef CONFIG_MIGRATION
>  
> +extern int PageMovable(struct page *page);
> +extern void __SetPageMovable(struct page *page, struct address_space *mapping);
> +extern void __ClearPageMovable(struct page *page);
>  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 new, free_page_t free,
>  		unsigned long private, enum migrate_mode mode, int reason);
> +extern bool isolate_movable_page(struct page *page, isolate_mode_t mode);
> +extern void putback_movable_page(struct page *page);
>  
>  extern int migrate_prep(void);
>  extern int migrate_prep_local(void);

__ClearPageMovable() is under CONFIG_MIGRATION in include/linux/migrate.h,
but zsmalloc checks for CONFIG_COMPACTION.

can we have stub declarations of movable functions for !CONFIG_MIGRATION builds?
otherwise the users (zsmalloc, for example) have to do things like

static void reset_page(struct page *page)
{
#ifdef CONFIG_COMPACTION
        __ClearPageMovable(page);
#endif
        clear_bit(PG_private, &page->flags);
        clear_bit(PG_private_2, &page->flags);
        set_page_private(page, 0);
        ClearPageHugeObject(page);
        page->freelist = NULL;
}

	-ss