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Commit 9d1ba805 authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by Linus Torvalds
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mm/balloon_compaction: remove balloon mapping and flag AS_BALLOON_MAP 



Now ballooned pages are detected using PageBalloon().  Fake mapping is no
longer required.  This patch links ballooned pages to balloon device using
field page->private instead of page->mapping.  Also this patch embeds
balloon_dev_info directly into struct virtio_balloon.

Signed-off-by: default avatarKonstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d6d86c0a

drivers/virtio/virtio_balloon.c

+13 −47
Original line number Diff line number Diff line
@@ -59,7 +59,7 @@ struct virtio_balloon 
	 * Each page on this list adds VIRTIO_BALLOON_PAGES_PER_PAGE

	 * to num_pages above.

	 */

	struct balloon_dev_info *vb_dev_info;

	struct balloon_dev_info vb_dev_info;



	/* Synchronize access/update to this struct virtio_balloon elements */

	struct mutex balloon_lock;
@@ -127,7 +127,7 @@ static void set_page_pfns(u32 pfns[], struct page *page) 


static void fill_balloon(struct virtio_balloon *vb, size_t num)

{

	struct balloon_dev_info *vb_dev_info = vb->vb_dev_info;

	struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;



	/* We can only do one array worth at a time. */

	num = min(num, ARRAY_SIZE(vb->pfns));
@@ -171,7 +171,7 @@ static void release_pages_by_pfn(const u32 pfns[], unsigned int num) 
static void leak_balloon(struct virtio_balloon *vb, size_t num)

{

	struct page *page;

	struct balloon_dev_info *vb_dev_info = vb->vb_dev_info;

	struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;



	/* We can only do one array worth at a time. */

	num = min(num, ARRAY_SIZE(vb->pfns));
@@ -353,12 +353,11 @@ static int init_vqs(struct virtio_balloon *vb) 
	return 0;

}



static const struct address_space_operations virtio_balloon_aops;

#ifdef CONFIG_BALLOON_COMPACTION

/*

 * virtballoon_migratepage - perform the balloon page migration on behalf of

 *			     a compation thread.     (called under page lock)

 * @mapping: the page->mapping which will be assigned to the new migrated page.

 * @vb_dev_info: the balloon device

 * @newpage: page that will replace the isolated page after migration finishes.

 * @page   : the isolated (old) page that is about to be migrated to newpage.

 * @mode   : compaction mode -- not used for balloon page migration.
@@ -373,17 +372,13 @@ static const struct address_space_operations virtio_balloon_aops; 
 * This function preforms the balloon page migration task.

 * Called through balloon_mapping->a_ops->migratepage

 */

static int virtballoon_migratepage(struct address_space *mapping,

static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,

		struct page *newpage, struct page *page, enum migrate_mode mode)

{

	struct balloon_dev_info *vb_dev_info = balloon_page_device(page);

	struct virtio_balloon *vb;

	struct virtio_balloon *vb = container_of(vb_dev_info,

			struct virtio_balloon, vb_dev_info);

	unsigned long flags;



	BUG_ON(!vb_dev_info);



	vb = vb_dev_info->balloon_device;



	/*

	 * In order to avoid lock contention while migrating pages concurrently

	 * to leak_balloon() or fill_balloon() we just give up the balloon_lock
@@ -399,7 +394,7 @@ static int virtballoon_migratepage(struct address_space *mapping, 


	/* balloon's page migration 1st step  -- inflate "newpage" */

	spin_lock_irqsave(&vb_dev_info->pages_lock, flags);

	balloon_page_insert(newpage, mapping, &vb_dev_info->pages);

	balloon_page_insert(vb_dev_info, newpage);

	vb_dev_info->isolated_pages--;

	spin_unlock_irqrestore(&vb_dev_info->pages_lock, flags);

	vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
@@ -418,18 +413,11 @@ static int virtballoon_migratepage(struct address_space *mapping, 


	return MIGRATEPAGE_SUCCESS;

}



/* define the balloon_mapping->a_ops callback to allow balloon page migration */

static const struct address_space_operations virtio_balloon_aops = {

			.migratepage = virtballoon_migratepage,

};

#endif /* CONFIG_BALLOON_COMPACTION */



static int virtballoon_probe(struct virtio_device *vdev)

{

	struct virtio_balloon *vb;

	struct address_space *vb_mapping;

	struct balloon_dev_info *vb_devinfo;

	int err;



	vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
@@ -445,30 +433,14 @@ static int virtballoon_probe(struct virtio_device *vdev) 
	vb->vdev = vdev;

	vb->need_stats_update = 0;



	vb_devinfo = balloon_devinfo_alloc(vb);

	if (IS_ERR(vb_devinfo)) {

		err = PTR_ERR(vb_devinfo);

		goto out_free_vb;

	}



	vb_mapping = balloon_mapping_alloc(vb_devinfo,

					   (balloon_compaction_check()) ?

					   &virtio_balloon_aops : NULL);

	if (IS_ERR(vb_mapping)) {

		/*

		 * IS_ERR(vb_mapping) && PTR_ERR(vb_mapping) == -EOPNOTSUPP

		 * This means !CONFIG_BALLOON_COMPACTION, otherwise we get off.

		 */

		err = PTR_ERR(vb_mapping);

		if (err != -EOPNOTSUPP)

			goto out_free_vb_devinfo;

	}



	vb->vb_dev_info = vb_devinfo;

	balloon_devinfo_init(&vb->vb_dev_info);

#ifdef CONFIG_BALLOON_COMPACTION

	vb->vb_dev_info.migratepage = virtballoon_migratepage;

#endif



	err = init_vqs(vb);

	if (err)

		goto out_free_vb_mapping;

		goto out_free_vb;



	vb->thread = kthread_run(balloon, vb, "vballoon");

	if (IS_ERR(vb->thread)) {
@@ -480,10 +452,6 @@ static int virtballoon_probe(struct virtio_device *vdev) 


out_del_vqs:

	vdev->config->del_vqs(vdev);

out_free_vb_mapping:

	balloon_mapping_free(vb_mapping);

out_free_vb_devinfo:

	balloon_devinfo_free(vb_devinfo);

out_free_vb:

	kfree(vb);

out:
@@ -509,8 +477,6 @@ static void virtballoon_remove(struct virtio_device *vdev) 


	kthread_stop(vb->thread);

	remove_common(vb);

	balloon_mapping_free(vb->vb_dev_info->mapping);

	balloon_devinfo_free(vb->vb_dev_info);

	kfree(vb);

}

include/linux/balloon_compaction.h

+19 −53
Original line number Diff line number Diff line
@@ -57,21 +57,22 @@ 
 * balloon driver as a page book-keeper for its registered balloon devices.

 */

struct balloon_dev_info {

	void *balloon_device;		/* balloon device descriptor */

	struct address_space *mapping;	/* balloon special page->mapping */

	unsigned long isolated_pages;	/* # of isolated pages for migration */

	spinlock_t pages_lock;		/* Protection to pages list */

	struct list_head pages;		/* Pages enqueued & handled to Host */

	int (*migratepage)(struct balloon_dev_info *, struct page *newpage,

			struct page *page, enum migrate_mode mode);

};



extern struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info);

extern struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info);

extern struct balloon_dev_info *balloon_devinfo_alloc(

						void *balloon_dev_descriptor);



static inline void balloon_devinfo_free(struct balloon_dev_info *b_dev_info)

static inline void balloon_devinfo_init(struct balloon_dev_info *balloon)

{

	kfree(b_dev_info);

	balloon->isolated_pages = 0;

	spin_lock_init(&balloon->pages_lock);

	INIT_LIST_HEAD(&balloon->pages);

	balloon->migratepage = NULL;

}



#ifdef CONFIG_BALLOON_COMPACTION
@@ -79,14 +80,6 @@ extern bool balloon_page_isolate(struct page *page); 
extern void balloon_page_putback(struct page *page);

extern int balloon_page_migrate(struct page *newpage,

				struct page *page, enum migrate_mode mode);

extern struct address_space

*balloon_mapping_alloc(struct balloon_dev_info *b_dev_info,

			const struct address_space_operations *a_ops);



static inline void balloon_mapping_free(struct address_space *balloon_mapping)

{

	kfree(balloon_mapping);

}



/*

 * __is_movable_balloon_page - helper to perform @page PageBalloon tests
@@ -120,27 +113,25 @@ static inline bool isolated_balloon_page(struct page *page) 


/*

 * balloon_page_insert - insert a page into the balloon's page list and make

 *		         the page->mapping assignment accordingly.

 *			 the page->private assignment accordingly.

 * @balloon : pointer to balloon device

 * @page    : page to be assigned as a 'balloon page'

 * @mapping : allocated special 'balloon_mapping'

 * @head    : balloon's device page list head

 *

 * Caller must ensure the page is locked and the spin_lock protecting balloon

 * pages list is held before inserting a page into the balloon device.

 */

static inline void balloon_page_insert(struct page *page,

				       struct address_space *mapping,

				       struct list_head *head)

static inline void balloon_page_insert(struct balloon_dev_info *balloon,

				       struct page *page)

{

	__SetPageBalloon(page);

	SetPagePrivate(page);

	page->mapping = mapping;

	list_add(&page->lru, head);

	set_page_private(page, (unsigned long)balloon);

	list_add(&page->lru, &balloon->pages);

}



/*

 * balloon_page_delete - delete a page from balloon's page list and clear

 *			 the page->mapping assignement accordingly.

 *			 the page->private assignement accordingly.

 * @page    : page to be released from balloon's page list

 *

 * Caller must ensure the page is locked and the spin_lock protecting balloon
@@ -149,7 +140,7 @@ static inline void balloon_page_insert(struct page *page, 
static inline void balloon_page_delete(struct page *page)

{

	__ClearPageBalloon(page);

	page->mapping = NULL;

	set_page_private(page, 0);

	if (PagePrivate(page)) {

		ClearPagePrivate(page);

		list_del(&page->lru);
@@ -162,11 +153,7 @@ static inline void balloon_page_delete(struct page *page) 
 */

static inline struct balloon_dev_info *balloon_page_device(struct page *page)

{

	struct address_space *mapping = page->mapping;

	if (likely(mapping))

		return mapping->private_data;



	return NULL;

	return (struct balloon_dev_info *)page_private(page);

}



static inline gfp_t balloon_mapping_gfp_mask(void)
@@ -174,29 +161,12 @@ static inline gfp_t balloon_mapping_gfp_mask(void) 
	return GFP_HIGHUSER_MOVABLE;

}



static inline bool balloon_compaction_check(void)

{

	return true;

}



#else /* !CONFIG_BALLOON_COMPACTION */



static inline void *balloon_mapping_alloc(void *balloon_device,

				const struct address_space_operations *a_ops)

{

	return ERR_PTR(-EOPNOTSUPP);

}



static inline void balloon_mapping_free(struct address_space *balloon_mapping)

static inline void balloon_page_insert(struct balloon_dev_info *balloon,

				       struct page *page)

{

	return;

}



static inline void balloon_page_insert(struct page *page,

				       struct address_space *mapping,

				       struct list_head *head)

{

	list_add(&page->lru, head);

	list_add(&page->lru, &balloon->pages);

}



static inline void balloon_page_delete(struct page *page)
@@ -240,9 +210,5 @@ static inline gfp_t balloon_mapping_gfp_mask(void) 
	return GFP_HIGHUSER;

}



static inline bool balloon_compaction_check(void)

{

	return false;

}

#endif /* CONFIG_BALLOON_COMPACTION */

#endif /* _LINUX_BALLOON_COMPACTION_H */

include/linux/pagemap.h

+1 −17
Original line number Diff line number Diff line
@@ -24,8 +24,7 @@ enum mapping_flags { 
	AS_ENOSPC	= __GFP_BITS_SHIFT + 1,	/* ENOSPC on async write */

	AS_MM_ALL_LOCKS	= __GFP_BITS_SHIFT + 2,	/* under mm_take_all_locks() */

	AS_UNEVICTABLE	= __GFP_BITS_SHIFT + 3,	/* e.g., ramdisk, SHM_LOCK */

	AS_BALLOON_MAP  = __GFP_BITS_SHIFT + 4, /* balloon page special map */

	AS_EXITING	= __GFP_BITS_SHIFT + 5, /* final truncate in progress */

	AS_EXITING	= __GFP_BITS_SHIFT + 4, /* final truncate in progress */

};



static inline void mapping_set_error(struct address_space *mapping, int error)
@@ -55,21 +54,6 @@ static inline int mapping_unevictable(struct address_space *mapping) 
	return !!mapping;

}



static inline void mapping_set_balloon(struct address_space *mapping)

{

	set_bit(AS_BALLOON_MAP, &mapping->flags);

}



static inline void mapping_clear_balloon(struct address_space *mapping)

{

	clear_bit(AS_BALLOON_MAP, &mapping->flags);

}



static inline int mapping_balloon(struct address_space *mapping)

{

	return mapping && test_bit(AS_BALLOON_MAP, &mapping->flags);

}



static inline void mapping_set_exiting(struct address_space *mapping)

{

	set_bit(AS_EXITING, &mapping->flags);

mm/balloon_compaction.c

+6 −89
Original line number Diff line number Diff line
@@ -10,32 +10,6 @@ 
#include <linux/export.h>

#include <linux/balloon_compaction.h>



/*

 * balloon_devinfo_alloc - allocates a balloon device information descriptor.

 * @balloon_dev_descriptor: pointer to reference the balloon device which

 *                          this struct balloon_dev_info will be servicing.

 *

 * Driver must call it to properly allocate and initialize an instance of

 * struct balloon_dev_info which will be used to reference a balloon device

 * as well as to keep track of the balloon device page list.

 */

struct balloon_dev_info *balloon_devinfo_alloc(void *balloon_dev_descriptor)

{

	struct balloon_dev_info *b_dev_info;

	b_dev_info = kmalloc(sizeof(*b_dev_info), GFP_KERNEL);

	if (!b_dev_info)

		return ERR_PTR(-ENOMEM);



	b_dev_info->balloon_device = balloon_dev_descriptor;

	b_dev_info->mapping = NULL;

	b_dev_info->isolated_pages = 0;

	spin_lock_init(&b_dev_info->pages_lock);

	INIT_LIST_HEAD(&b_dev_info->pages);



	return b_dev_info;

}

EXPORT_SYMBOL_GPL(balloon_devinfo_alloc);



/*

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

 *			  page list.
@@ -61,7 +35,7 @@ struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info) 
	 */

	BUG_ON(!trylock_page(page));

	spin_lock_irqsave(&b_dev_info->pages_lock, flags);

	balloon_page_insert(page, b_dev_info->mapping, &b_dev_info->pages);

	balloon_page_insert(b_dev_info, page);

	spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);

	unlock_page(page);

	return page;
@@ -127,60 +101,10 @@ struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info) 
EXPORT_SYMBOL_GPL(balloon_page_dequeue);



#ifdef CONFIG_BALLOON_COMPACTION

/*

 * balloon_mapping_alloc - allocates a special ->mapping for ballooned pages.

 * @b_dev_info: holds the balloon device information descriptor.

 * @a_ops: balloon_mapping address_space_operations descriptor.

 *

 * Driver must call it to properly allocate and initialize an instance of

 * struct address_space which will be used as the special page->mapping for

 * balloon device enlisted page instances.

 */

struct address_space *balloon_mapping_alloc(struct balloon_dev_info *b_dev_info,

				const struct address_space_operations *a_ops)

{

	struct address_space *mapping;



	mapping = kmalloc(sizeof(*mapping), GFP_KERNEL);

	if (!mapping)

		return ERR_PTR(-ENOMEM);



	/*

	 * Give a clean 'zeroed' status to all elements of this special

	 * balloon page->mapping struct address_space instance.

	 */

	address_space_init_once(mapping);



	/*

	 * Set mapping->flags appropriately, to allow balloon pages

	 * ->mapping identification.

	 */

	mapping_set_balloon(mapping);

	mapping_set_gfp_mask(mapping, balloon_mapping_gfp_mask());



	/* balloon's page->mapping->a_ops callback descriptor */

	mapping->a_ops = a_ops;



	/*

	 * Establish a pointer reference back to the balloon device descriptor

	 * this particular page->mapping will be servicing.

	 * This is used by compaction / migration procedures to identify and

	 * access the balloon device pageset while isolating / migrating pages.

	 *

	 * As some balloon drivers can register multiple balloon devices

	 * for a single guest, this also helps compaction / migration to

	 * properly deal with multiple balloon pagesets, when required.

	 */

	mapping->private_data = b_dev_info;

	b_dev_info->mapping = mapping;



	return mapping;

}

EXPORT_SYMBOL_GPL(balloon_mapping_alloc);



static inline void __isolate_balloon_page(struct page *page)

{

	struct balloon_dev_info *b_dev_info = page->mapping->private_data;

	struct balloon_dev_info *b_dev_info = balloon_page_device(page);

	unsigned long flags;



	spin_lock_irqsave(&b_dev_info->pages_lock, flags);
@@ -192,7 +116,7 @@ static inline void __isolate_balloon_page(struct page *page) 


static inline void __putback_balloon_page(struct page *page)

{

	struct balloon_dev_info *b_dev_info = page->mapping->private_data;

	struct balloon_dev_info *b_dev_info = balloon_page_device(page);

	unsigned long flags;



	spin_lock_irqsave(&b_dev_info->pages_lock, flags);
@@ -202,12 +126,6 @@ static inline void __putback_balloon_page(struct page *page) 
	spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);

}



static inline int __migrate_balloon_page(struct address_space *mapping,

		struct page *newpage, struct page *page, enum migrate_mode mode)

{

	return page->mapping->a_ops->migratepage(mapping, newpage, page, mode);

}



/* __isolate_lru_page() counterpart for a ballooned page */

bool balloon_page_isolate(struct page *page)

{
@@ -274,7 +192,7 @@ void balloon_page_putback(struct page *page) 
int balloon_page_migrate(struct page *newpage,

			 struct page *page, enum migrate_mode mode)

{

	struct address_space *mapping;

	struct balloon_dev_info *balloon = balloon_page_device(page);

	int rc = -EAGAIN;



	/*
@@ -290,9 +208,8 @@ int balloon_page_migrate(struct page *newpage, 
		return rc;

	}



	mapping = page->mapping;

	if (mapping)

		rc = __migrate_balloon_page(mapping, newpage, page, mode);

	if (balloon && balloon->migratepage)

		rc = balloon->migratepage(balloon, newpage, page, mode);



	unlock_page(newpage);

	return rc;