linux-imx

/*

 * mm/balloon_compaction.c

 *

 * Common interface for making balloon pages movable by compaction.

 *

 * Copyright (C) 2012, Red Hat, Inc.  Rafael Aquini <aquini@redhat.com>

 */

#include <linux/mm.h>

#include <linux/slab.h>

#include <linux/export.h>

#include <linux/balloon_compaction.h>

​

/*

 * balloon_page_alloc - allocates a new page for insertion into the balloon

 *            page list.

 *

 * Driver must call it to properly allocate a new enlisted balloon page.

 * Driver must call balloon_page_enqueue before definitively removing it from

 * the guest system.  This function returns the page address for the recently

 * allocated page or NULL in the case we fail to allocate a new page this turn.

 */

struct page *balloon_page_alloc(void)

{

    struct page *page = alloc_page(balloon_mapping_gfp_mask() |

                       __GFP_NOMEMALLOC | __GFP_NORETRY);

    return page;

}

EXPORT_SYMBOL_GPL(balloon_page_alloc);

​

/*

 * balloon_page_enqueue - allocates a new page and inserts it into the balloon

 *            page list.

 * @b_dev_info: balloon device descriptor where we will insert a new page to

 * @page: new page to enqueue - allocated using balloon_page_alloc.

 *

 * Driver must call it to properly enqueue a new allocated balloon page

 * before definitively removing it from the guest system.

 * This function returns the page address for the recently enqueued page or

 * NULL in the case we fail to allocate a new page this turn.

 */

void balloon_page_enqueue(struct balloon_dev_info *b_dev_info,

              struct page *page)

{

    unsigned long flags;

​

    /*

     * Block others from accessing the 'page' when we get around to

     * establishing additional references. We should be the only one

     * holding a reference to the 'page' at this point.

     */

    BUG_ON(!trylock_page(page));

    spin_lock_irqsave(&b_dev_info->pages_lock, flags);

    balloon_page_insert(b_dev_info, page);

    __count_vm_event(BALLOON_INFLATE);

    spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);

    unlock_page(page);

}

EXPORT_SYMBOL_GPL(balloon_page_enqueue);

​

/*

 * balloon_page_dequeue - removes a page from balloon's page list and returns

 *            the its address to allow the driver release the page.

 * @b_dev_info: balloon device decriptor where we will grab a page from.