[PATCH v2 6/6] mm/balloon_compaction: general cleanup

From: Konstantin Khlebnikov
Date: Sat Aug 30 2014 - 12:41:59 EST

From: Konstantin Khlebnikov <k.khlebnikov@xxxxxxxxxxx>

* move special branch for balloon migraion into migrate_pages
* remove special mapping for balloon and its flag AS_BALLOON_MAP
* embed struct balloon_dev_info into struct virtio_balloon
* cleanup balloon_page_dequeue, kill balloon_page_free

Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@xxxxxxxxxxx>
---
drivers/virtio/virtio_balloon.c | 77 ++++---------
include/linux/balloon_compaction.h | 127 ++++++---------------
include/linux/migrate.h | 11 --
include/linux/pagemap.h | 18 ---
mm/balloon_compaction.c | 214 ++++++++++++------------------------
mm/migrate.c | 29 +----
6 files changed, 134 insertions(+), 342 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 25ebe8e..c84d6a8 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -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));
@@ -163,15 +163,15 @@ static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
/* Find pfns pointing at start of each page, get pages and free them. */
for (i = 0; i < num; i += VIRTIO_BALLOON_PAGES_PER_PAGE) {
struct page *page = balloon_pfn_to_page(pfns[i]);
- balloon_page_free(page);
adjust_managed_page_count(page, 1);
+ put_page(page);
}
}

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
@@ -395,42 +390,34 @@ static int virtballoon_migratepage(struct address_space *mapping,
if (!mutex_trylock(&vb->balloon_lock))
return -EAGAIN;

+ get_page(newpage); /* balloon reference */
+
/* 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;
set_page_pfns(vb->pfns, newpage);
tell_host(vb, vb->inflate_vq);

- /*
- * balloon's page migration 2nd step -- deflate "page"
- *
- * It's safe to delete page->lru here because this page is at
- * an isolated migration list, and this step is expected to happen here
- */
- balloon_page_delete(page);
+ /* balloon's page migration 2nd step -- deflate "page" */
+ balloon_page_delete(page, true);
vb->num_pfns = VIRTIO_BALLOON_PAGES_PER_PAGE;
set_page_pfns(vb->pfns, page);
tell_host(vb, vb->deflate_vq);

mutex_unlock(&vb->balloon_lock);

- return MIGRATEPAGE_BALLOON_SUCCESS;
-}
+ put_page(page); /* balloon reference */

-/* define the balloon_mapping->a_ops callback to allow balloon page migration */
-static const struct address_space_operations virtio_balloon_aops = {
- .migratepage = virtballoon_migratepage,
-};
+ return MIGRATEPAGE_SUCCESS;
+}
#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);
@@ -446,30 +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)) {
@@ -481,10 +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:
@@ -510,8 +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);
}

diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h
index 09f8c5a..ad112fcc6 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon_compaction.h
@@ -56,96 +56,58 @@
* 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 *b_dev_info)
{
- kfree(b_dev_info);
+ b_dev_info->isolated_pages = 0;
+ spin_lock_init(&b_dev_info->pages_lock);
+ INIT_LIST_HEAD(&b_dev_info->pages);
+ b_dev_info->migratepage = NULL;
}

-/*
- * balloon_page_free - release a balloon page back to the page free lists
- * @page: ballooned page to be set free
- *
- * This function must be used to properly set free an isolated/dequeued balloon
- * page at the end of a sucessful page migration, or at the balloon driver's
- * page release procedure.
- */
-static inline void balloon_page_free(struct page *page)
-{
- /*
- * Balloon pages always get an extra refcount before being isolated
- * and before being dequeued to help on sorting out fortuite colisions
- * between a thread attempting to isolate and another thread attempting
- * to release the very same balloon page.
- *
- * Before we handle the page back to Buddy, lets drop its extra refcnt.
- */
- put_page(page);
- __free_page(page);
-}
+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);

/*
- * balloon_page_insert - insert a page into the balloon's page list and make
- * the page->mapping assignment accordingly.
- * @page : page to be assigned as a 'balloon page'
- * @mapping : allocated special 'balloon_mapping'
- * @head : balloon's device page list head
+ * balloon_page_insert - insert a page into the balloon's page list,
+ * mark and account it accordingly.
+ * @b_dev_info : pinter to ballon device
+ * @page : page to be assigned as a 'balloon page'
*
* 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 *b_dev_info, struct page *page)
{
__SetPageBalloon(page);
inc_zone_page_state(page, NR_BALLOON_PAGES);
- page->mapping = mapping;
- list_add(&page->lru, head);
+ set_page_private(page, (unsigned long)b_dev_info);
+ list_add(&page->lru, &b_dev_info->pages);
}

/*
* balloon_page_delete - delete a page from balloon's page list and clear
- * the page->mapping assignement accordingly.
+ * the ballon page mark accordingly.
* @page : page to be released from balloon's page list
+ * @isolated: already isolated, do not delete from list
*
* Caller must ensure the page is locked and the spin_lock protecting balloon
* pages list is held before deleting a page from the balloon device.
*/
-static inline void balloon_page_delete(struct page *page)
+static inline void balloon_page_delete(struct page *page, bool isolated)
{
__ClearPageBalloon(page);
dec_zone_page_state(page, NR_BALLOON_PAGES);
- page->mapping = NULL;
- list_del(&page->lru);
-}
-
-#endif /* CONFIG_MEMORY_BALLOON */
-
-#ifdef CONFIG_BALLOON_COMPACTION
-
-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);
+ set_page_private(page, 0);
+ if (!isolated)
+ list_del(&page->lru);
}

/*
@@ -154,35 +116,25 @@ static inline void balloon_mapping_free(struct address_space *balloon_mapping)
*/
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)
-{
- return GFP_HIGHUSER_MOVABLE;
-}
+#endif /* CONFIG_MEMORY_BALLOON */

-static inline bool balloon_compaction_check(void)
-{
- return true;
-}
+#ifdef CONFIG_BALLOON_COMPACTION
+extern bool balloon_page_isolate(struct page *page);
+extern void balloon_page_putback(struct page *page);

-#else /* !CONFIG_BALLOON_COMPACTION */
+int balloon_page_migrate(new_page_t get_new_page, free_page_t put_new_page,
+ unsigned long private, struct page *page,
+ int force, enum migrate_mode mode);

-static inline void *balloon_mapping_alloc(void *balloon_device,
- const struct address_space_operations *a_ops)
+static inline gfp_t balloon_mapping_gfp_mask(void)
{
- return ERR_PTR(-EOPNOTSUPP);
+ return GFP_HIGHUSER_MOVABLE;
}

-static inline void balloon_mapping_free(struct address_space *balloon_mapping)
-{
- return;
-}
+#else /* !CONFIG_BALLOON_COMPACTION */

static inline bool balloon_page_isolate(struct page *page)
{
@@ -194,10 +146,11 @@ static inline void balloon_page_putback(struct page *page)
return;
}

-static inline int balloon_page_migrate(struct page *newpage,
- struct page *page, enum migrate_mode mode)
+static inline int balloon_page_migrate(new_page_t get_new_page,
+ free_page_t put_new_page, unsigned long private,
+ struct page *page, int force, enum migrate_mode mode)
{
- return 0;
+ return -EAGAIN;
}

static inline gfp_t balloon_mapping_gfp_mask(void)
@@ -205,9 +158,5 @@ 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 */
diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 0a4604a..cf90776 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -13,18 +13,9 @@ typedef void free_page_t(struct page *page, unsigned long private);
* Return values from addresss_space_operations.migratepage():
* - negative errno on page migration failure;
* - zero on page migration success;
- *
- * The balloon page migration introduces this special case where a 'distinct'
- * return code is used to flag a successful page migration to unmap_and_move().
- * This approach is necessary because page migration can race against balloon
- * deflation procedure, and for such case we could introduce a nasty page leak
- * if a successfully migrated balloon page gets released concurrently with
- * migration's unmap_and_move() wrap-up steps.
*/
#define MIGRATEPAGE_SUCCESS 0
-#define MIGRATEPAGE_BALLOON_SUCCESS 1 /* special ret code for balloon page
- * sucessful migration case.
- */
+
enum migrate_reason {
MR_COMPACTION,
MR_MEMORY_FAILURE,
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 5ba1813..210b46b 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -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);
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index a942081..3c8cb7a 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -11,32 +11,6 @@
#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.
* @b_dev_info: balloon device decriptor where we will insert a new page to
@@ -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;
@@ -81,12 +55,10 @@ EXPORT_SYMBOL_GPL(balloon_page_enqueue);
*/
struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
{
- struct page *page, *tmp;
+ struct page *page;
unsigned long flags;
- bool dequeued_page;

- dequeued_page = false;
- list_for_each_entry_safe(page, tmp, &b_dev_info->pages, lru) {
+ list_for_each_entry(page, &b_dev_info->pages, lru) {
/*
* Block others from accessing the 'page' while we get around
* establishing additional references and preparing the 'page'
@@ -94,98 +66,32 @@ struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
*/
if (trylock_page(page)) {
spin_lock_irqsave(&b_dev_info->pages_lock, flags);
- /*
- * Raise the page refcount here to prevent any wrong
- * attempt to isolate this page, in case of coliding
- * with balloon_page_isolate() just after we release
- * the page lock.
- *
- * balloon_page_free() will take care of dropping
- * this extra refcount later.
- */
- get_page(page);
- balloon_page_delete(page);
+ balloon_page_delete(page, false);
spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
unlock_page(page);
- dequeued_page = true;
- break;
+ return page;
}
}

- if (!dequeued_page) {
- /*
- * If we are unable to dequeue a balloon page because the page
- * list is empty and there is no isolated pages, then something
- * went out of track and some balloon pages are lost.
- * BUG() here, otherwise the balloon driver may get stuck into
- * an infinite loop while attempting to release all its pages.
- */
- spin_lock_irqsave(&b_dev_info->pages_lock, flags);
- if (unlikely(list_empty(&b_dev_info->pages) &&
- !b_dev_info->isolated_pages))
- BUG();
- spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
- page = NULL;
- }
- return page;
+ /*
+ * If we are unable to dequeue a balloon page because the page
+ * list is empty and there is no isolated pages, then something
+ * went out of track and some balloon pages are lost.
+ * BUG() here, otherwise the balloon driver may get stuck into
+ * an infinite loop while attempting to release all its pages.
+ */
+ spin_lock_irqsave(&b_dev_info->pages_lock, flags);
+ BUG_ON(list_empty(&b_dev_info->pages) && !b_dev_info->isolated_pages);
+ spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+ return NULL;
}
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);
list_del(&page->lru);
@@ -195,7 +101,7 @@ 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);
list_add(&page->lru, &b_dev_info->pages);
@@ -203,12 +109,6 @@ 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)
{
@@ -251,6 +151,57 @@ bool balloon_page_isolate(struct page *page)
return false;
}

+int balloon_page_migrate(new_page_t get_new_page, free_page_t put_new_page,
+ unsigned long private, struct page *page,
+ int force, enum migrate_mode mode)
+{
+ struct balloon_dev_info *balloon = balloon_page_device(page);
+ struct page *newpage;
+ int *result = NULL;
+ int rc = -EAGAIN;
+
+ if (!balloon || !balloon->migratepage)
+ return -EAGAIN;
+
+ newpage = get_new_page(page, private, &result);
+ if (!newpage)
+ return -ENOMEM;
+
+ if (!trylock_page(newpage))
+ BUG();
+
+ if (!trylock_page(page)) {
+ if (!force || mode != MIGRATE_SYNC)
+ goto out;
+ lock_page(page);
+ }
+
+ rc = balloon->migratepage(balloon, newpage, page, mode);
+
+ unlock_page(page);
+out:
+ unlock_page(newpage);
+
+ if (rc != -EAGAIN) {
+ dec_zone_page_state(page, NR_ISOLATED_FILE);
+ list_del(&page->lru);
+ put_page(page);
+ }
+
+ if (rc != MIGRATEPAGE_SUCCESS && put_new_page)
+ put_new_page(newpage, private);
+ else
+ put_page(newpage);
+
+ if (result) {
+ if (rc)
+ *result = rc;
+ else
+ *result = page_to_nid(newpage);
+ }
+ return rc;
+}
+
/* putback_lru_page() counterpart for a ballooned page */
void balloon_page_putback(struct page *page)
{
@@ -271,31 +222,4 @@ void balloon_page_putback(struct page *page)
unlock_page(page);
}

-/* move_to_new_page() counterpart for a ballooned page */
-int balloon_page_migrate(struct page *newpage,
- struct page *page, enum migrate_mode mode)
-{
- struct address_space *mapping;
- int rc = -EAGAIN;
-
- /*
- * Block others from accessing the 'newpage' when we get around to
- * establishing additional references. We should be the only one
- * holding a reference to the 'newpage' at this point.
- */
- BUG_ON(!trylock_page(newpage));
-
- if (WARN_ON(!PageBalloon(page))) {
- dump_page(page, "not movable balloon page");
- unlock_page(newpage);
- return rc;
- }
-
- mapping = page->mapping;
- if (mapping)
- rc = __migrate_balloon_page(mapping, newpage, page, mode);
-
- unlock_page(newpage);
- return rc;
-}
#endif /* CONFIG_BALLOON_COMPACTION */
diff --git a/mm/migrate.c b/mm/migrate.c
index a4939b1..e6d0d2d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -873,18 +873,6 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
}
}

- if (unlikely(PageBalloon(page))) {
- /*
- * A ballooned page does not need any special attention from
- * physical to virtual reverse mapping procedures.
- * Skip any attempt to unmap PTEs or to remap swap cache,
- * in order to avoid burning cycles at rmap level, and perform
- * the page migration right away (proteced by page lock).
- */
- rc = balloon_page_migrate(newpage, page, mode);
- goto out_unlock;
- }
-
/*
* Corner case handling:
* 1. When a new swap-cache page is read into, it is added to the LRU
@@ -952,19 +940,6 @@ static int unmap_and_move(new_page_t get_new_page, free_page_t put_new_page,

rc = __unmap_and_move(page, newpage, force, mode);

-#ifdef CONFIG_MEMORY_BALLOON
- if (unlikely(rc == MIGRATEPAGE_BALLOON_SUCCESS)) {
- /*
- * A ballooned page has been migrated already.
- * Now, it's the time to wrap-up counters,
- * handle the page back to Buddy and return.
- */
- dec_zone_page_state(page, NR_ISOLATED_ANON +
- page_is_file_cache(page));
- balloon_page_free(page);
- return MIGRATEPAGE_SUCCESS;
- }
-#endif
out:
if (rc != -EAGAIN) {
/*
@@ -1139,6 +1114,10 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
rc = unmap_and_move_huge_page(get_new_page,
put_new_page, private, page,
pass > 2, mode);
+ else if (PageBalloon(page))
+ rc = balloon_page_migrate(get_new_page,
+ put_new_page, private,
+ page, pass > 2, mode);
else
rc = unmap_and_move(get_new_page, put_new_page,
private, page, pass > 2, mode);

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