[RFC 2/4] mm/balloon: apply driver page migratable into balloon driver
From: Gioh Kim
Date: Tue Jun 02 2015 - 03:31:02 EST
Apply driver page migration into balloon driver.
Signed-off-by: Gioh Kim <gioh.kim@xxxxxxx>
---
drivers/virtio/virtio_balloon.c | 2 ++
fs/proc/page.c | 4 +--
include/linux/balloon_compaction.h | 42 ++++++++++++++++-------
include/linux/mm.h | 19 -----------
include/uapi/linux/kernel-page-flags.h | 2 +-
mm/balloon_compaction.c | 61 ++++++++++++++++++++++++++++++++--
6 files changed, 94 insertions(+), 36 deletions(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 6a356e3..cdd0038 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -496,6 +496,8 @@ static int virtballoon_probe(struct virtio_device *vdev)
balloon_devinfo_init(&vb->vb_dev_info);
#ifdef CONFIG_BALLOON_COMPACTION
vb->vb_dev_info.migratepage = virtballoon_migratepage;
+ vb->vb_dev_info.mapping = balloon_mapping_alloc(&vb->vb_dev_info,
+ &balloon_aops);
#endif
err = init_vqs(vb);
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 7eee2d8..e741307 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -143,8 +143,8 @@ u64 stable_page_flags(struct page *page)
if (PageBuddy(page))
u |= 1 << KPF_BUDDY;
- if (PageBalloon(page))
- u |= 1 << KPF_BALLOON;
+ if (PageMigratable(page))
+ u |= 1 << KPF_MIGRATABLE;
u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h
index 9b0a15d..0989e96 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon_compaction.h
@@ -48,6 +48,7 @@
#include <linux/migrate.h>
#include <linux/gfp.h>
#include <linux/err.h>
+#include <linux/fs.h>
/*
* Balloon device information descriptor.
@@ -62,6 +63,7 @@ struct balloon_dev_info {
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);
+ struct address_space *mapping;
};
extern struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info);
@@ -73,24 +75,37 @@ static inline void balloon_devinfo_init(struct balloon_dev_info *balloon)
spin_lock_init(&balloon->pages_lock);
INIT_LIST_HEAD(&balloon->pages);
balloon->migratepage = NULL;
+ balloon->mapping = NULL;
}
#ifdef CONFIG_BALLOON_COMPACTION
-extern bool balloon_page_isolate(struct page *page);
+extern const struct address_space_operations balloon_aops;
+extern bool balloon_page_isolate(struct page *page,
+ isolate_mode_t mode);
extern void balloon_page_putback(struct page *page);
-extern int balloon_page_migrate(struct page *newpage,
+extern int balloon_page_migrate(struct address_space *mapping,
+ 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
+ * __is_movable_balloon_page - helper to perform @page PageMigratable tests
*/
static inline bool __is_movable_balloon_page(struct page *page)
{
- return PageBalloon(page);
+ return PageMigratable(page);
}
/*
- * balloon_page_movable - test PageBalloon to identify balloon pages
+ * balloon_page_movable - test PageMigratable to identify balloon pages
* and PagePrivate to check that the page is not
* isolated and can be moved by compaction/migration.
*
@@ -99,7 +114,7 @@ static inline bool __is_movable_balloon_page(struct page *page)
*/
static inline bool balloon_page_movable(struct page *page)
{
- return PageBalloon(page) && PagePrivate(page);
+ return PageMigratable(page) && PagePrivate(page);
}
/*
@@ -108,7 +123,7 @@ static inline bool balloon_page_movable(struct page *page)
*/
static inline bool isolated_balloon_page(struct page *page)
{
- return PageBalloon(page);
+ return PageMigratable(page);
}
/*
@@ -123,7 +138,8 @@ static inline bool isolated_balloon_page(struct page *page)
static inline void balloon_page_insert(struct balloon_dev_info *balloon,
struct page *page)
{
- __SetPageBalloon(page);
+ page->mapping = balloon->mapping;
+ __SetPageMigratable(page);
SetPagePrivate(page);
set_page_private(page, (unsigned long)balloon);
list_add(&page->lru, &balloon->pages);
@@ -139,7 +155,8 @@ static inline void balloon_page_insert(struct balloon_dev_info *balloon,
*/
static inline void balloon_page_delete(struct page *page)
{
- __ClearPageBalloon(page);
+ page->mapping = NULL;
+ __ClearPageMigratable(page);
set_page_private(page, 0);
if (PagePrivate(page)) {
ClearPagePrivate(page);
@@ -166,13 +183,13 @@ static inline gfp_t balloon_mapping_gfp_mask(void)
static inline void balloon_page_insert(struct balloon_dev_info *balloon,
struct page *page)
{
- __SetPageBalloon(page);
+ __SetPageMigratable(page);
list_add(&page->lru, &balloon->pages);
}
static inline void balloon_page_delete(struct page *page)
{
- __ClearPageBalloon(page);
+ __ClearPageMigratable(page);
list_del(&page->lru);
}
@@ -191,7 +208,8 @@ static inline bool isolated_balloon_page(struct page *page)
return false;
}
-static inline bool balloon_page_isolate(struct page *page)
+static inline bool balloon_page_isolate(struct page *page,
+ isolate_mode_t mode)
{
return false;
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 422c484..2d991a0 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -599,25 +599,6 @@ static inline void __ClearPageBuddy(struct page *page)
atomic_set(&page->_mapcount, -1);
}
-#define PAGE_BALLOON_MAPCOUNT_VALUE (-256)
-
-static inline int PageBalloon(struct page *page)
-{
- return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
-}
-
-static inline void __SetPageBalloon(struct page *page)
-{
- VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
- atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
-}
-
-static inline void __ClearPageBalloon(struct page *page)
-{
- VM_BUG_ON_PAGE(!PageBalloon(page), page);
- atomic_set(&page->_mapcount, -1);
-}
-
#define PAGE_MIGRATABLE_MAPCOUNT_VALUE (-256)
static inline int PageMigratable(struct page *page)
diff --git a/include/uapi/linux/kernel-page-flags.h b/include/uapi/linux/kernel-page-flags.h
index a6c4962..a6a3c4b 100644
--- a/include/uapi/linux/kernel-page-flags.h
+++ b/include/uapi/linux/kernel-page-flags.h
@@ -31,7 +31,7 @@
#define KPF_KSM 21
#define KPF_THP 22
-#define KPF_BALLOON 23
+#define KPF_MIGRATABLE 23
#define KPF_ZERO_PAGE 24
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index fcad832..f98a500 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -131,7 +131,7 @@ static inline void __putback_balloon_page(struct page *page)
}
/* __isolate_lru_page() counterpart for a ballooned page */
-bool balloon_page_isolate(struct page *page)
+bool balloon_page_isolate(struct page *page, isolate_mode_t mode)
{
/*
* Avoid burning cycles with pages that are yet under __free_pages(),
@@ -175,6 +175,9 @@ bool balloon_page_isolate(struct page *page)
/* putback_lru_page() counterpart for a ballooned page */
void balloon_page_putback(struct page *page)
{
+ if (!isolated_balloon_page(page))
+ return;
+
/*
* 'lock_page()' stabilizes the page and prevents races against
* concurrent isolation threads attempting to re-isolate it.
@@ -193,12 +196,16 @@ void balloon_page_putback(struct page *page)
}
/* move_to_new_page() counterpart for a ballooned page */
-int balloon_page_migrate(struct page *newpage,
+int balloon_page_migrate(struct address_space *mapping,
+ struct page *newpage,
struct page *page, enum migrate_mode mode)
{
struct balloon_dev_info *balloon = balloon_page_device(page);
int rc = -EAGAIN;
+ if (!isolated_balloon_page(page))
+ return rc;
+
/*
* Block others from accessing the 'newpage' when we get around to
* establishing additional references. We should be the only one
@@ -218,4 +225,54 @@ int balloon_page_migrate(struct page *newpage,
unlock_page(newpage);
return rc;
}
+
+/* define the balloon_mapping->a_ops callback to allow balloon page migration */
+const struct address_space_operations balloon_aops = {
+ .migratepage = balloon_page_migrate,
+ .isolatepage = balloon_page_isolate,
+ .putbackpage = balloon_page_putback,
+};
+EXPORT_SYMBOL_GPL(balloon_aops);
+
+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_migratable(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);
#endif /* CONFIG_BALLOON_COMPACTION */
--
1.9.1
--
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