* counter raised only while it is under our special handling;
*
* iii. after the lockless scan step have selected a potential balloon page for
- * isolation, re-test the page->mapping flags and the page ref counter
+ * isolation, re-test the PageBalloon mark and the PagePrivate flag
* under the proper page lock, to ensure isolating a valid balloon page
* (not yet isolated, nor under release procedure)
*
+ * iv. isolation or dequeueing procedure must clear PagePrivate flag under
+ * page lock together with removing page from balloon device page list.
+ *
* The functions provided by this interface are placed to help on coping with
* the aforementioned balloon page corner case, as well as to ensure the simple
* set of exposed rules are satisfied while we are dealing with balloon pages
kfree(b_dev_info);
}
-/*
- * 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);
-}
-
#ifdef CONFIG_BALLOON_COMPACTION
extern bool balloon_page_isolate(struct page *page);
extern void balloon_page_putback(struct page *page);
}
/*
- * page_flags_cleared - helper to perform balloon @page ->flags tests.
- *
- * As balloon pages are obtained from buddy and we do not play with page->flags
- * at driver level (exception made when we get the page lock for compaction),
- * we can safely identify a ballooned page by checking if the
- * PAGE_FLAGS_CHECK_AT_PREP page->flags are all cleared. This approach also
- * helps us skip ballooned pages that are locked for compaction or release, thus
- * mitigating their racy check at balloon_page_movable()
- */
-static inline bool page_flags_cleared(struct page *page)
-{
- return !(page->flags & PAGE_FLAGS_CHECK_AT_PREP);
-}
-
-/*
- * __is_movable_balloon_page - helper to perform @page mapping->flags tests
+ * __is_movable_balloon_page - helper to perform @page PageBalloon tests
*/
static inline bool __is_movable_balloon_page(struct page *page)
{
- struct address_space *mapping = page->mapping;
- return mapping_balloon(mapping);
+ return PageBalloon(page);
}
/*
- * balloon_page_movable - test page->mapping->flags to identify balloon pages
- * that can be moved by compaction/migration.
- *
- * This function is used at core compaction's page isolation scheme, therefore
- * most pages exposed to it are not enlisted as balloon pages and so, to avoid
- * undesired side effects like racing against __free_pages(), we cannot afford
- * holding the page locked while testing page->mapping->flags here.
+ * balloon_page_movable - test PageBalloon to identify balloon pages
+ * and PagePrivate to check that the page is not
+ * isolated and can be moved by compaction/migration.
*
* As we might return false positives in the case of a balloon page being just
- * released under us, the page->mapping->flags need to be re-tested later,
- * under the proper page lock, at the functions that will be coping with the
- * balloon page case.
+ * released under us, this need to be re-tested later, under the page lock.
*/
static inline bool balloon_page_movable(struct page *page)
{
- /*
- * Before dereferencing and testing mapping->flags, let's make sure
- * this is not a page that uses ->mapping in a different way
- */
- if (page_flags_cleared(page) && !page_mapped(page) &&
- page_count(page) == 1)
- return __is_movable_balloon_page(page);
-
- return false;
+ return PageBalloon(page) && PagePrivate(page);
}
/*
* isolated_balloon_page - identify an isolated balloon page on private
* compaction/migration page lists.
- *
- * After a compaction thread isolates a balloon page for migration, it raises
- * the page refcount to prevent concurrent compaction threads from re-isolating
- * the same page. For that reason putback_movable_pages(), or other routines
- * that need to identify isolated balloon pages on private pagelists, cannot
- * rely on balloon_page_movable() to accomplish the task.
*/
static inline bool isolated_balloon_page(struct page *page)
{
- /* Already isolated balloon pages, by default, have a raised refcount */
- if (page_flags_cleared(page) && !page_mapped(page) &&
- page_count(page) >= 2)
- return __is_movable_balloon_page(page);
-
- return false;
+ return PageBalloon(page);
}
/*
struct address_space *mapping,
struct list_head *head)
{
+ __SetPageBalloon(page);
+ SetPagePrivate(page);
page->mapping = mapping;
list_add(&page->lru, head);
}
*/
static inline void balloon_page_delete(struct page *page)
{
+ __ClearPageBalloon(page);
page->mapping = NULL;
- list_del(&page->lru);
+ if (PagePrivate(page)) {
+ ClearPagePrivate(page);
+ list_del(&page->lru);
+ }
}
/*
list_del(&page->lru);
}
+static inline bool __is_movable_balloon_page(struct page *page)
+{
+ return false;
+}
+
static inline bool balloon_page_movable(struct page *page)
{
return false;
projects / linux-2.6-microblaze.git / blobdiff