diff options
Diffstat (limited to 'include/linux/balloon_compaction.h')
| -rw-r--r-- | include/linux/balloon_compaction.h | 34 |
1 files changed, 13 insertions, 21 deletions
diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h index 53051f3d8f25..f111c780ef1d 100644 --- a/include/linux/balloon_compaction.h +++ b/include/linux/balloon_compaction.h @@ -4,15 +4,18 @@ * * Common interface definitions for making balloon pages movable by compaction. * - * Despite being perfectly possible to perform ballooned pages migration, they - * make a special corner case to compaction scans because balloon pages are not - * enlisted at any LRU list like the other pages we do compact / migrate. + * Balloon page migration makes use of the general non-lru movable page + * feature. + * + * page->private is used to reference the responsible balloon device. + * page->mapping is used in context of non-lru page migration to reference + * the address space operations for page isolation/migration/compaction. * * As the page isolation scanning step a compaction thread does is a lockless * procedure (from a page standpoint), it might bring some racy situations while * performing balloon page compaction. In order to sort out these racy scenarios * and safely perform balloon's page compaction and migration we must, always, - * ensure following these three simple rules: + * ensure following these simple rules: * * i. when updating a balloon's page ->mapping element, strictly do it under * the following lock order, independently of the far superior @@ -21,19 +24,8 @@ * +--spin_lock_irq(&b_dev_info->pages_lock); * ... page->mapping updates here ... * - * ii. before isolating or dequeueing a balloon page from the balloon device - * pages list, the page reference counter must be raised by one and the - * extra refcount must be dropped when the page is enqueued back into - * the balloon device page list, thus a balloon page keeps its reference - * 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 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. + * ii. isolation or dequeueing procedure must remove the page from balloon + * device page list under b_dev_info->pages_lock. * * 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 @@ -103,7 +95,7 @@ extern int balloon_page_migrate(struct address_space *mapping, static inline void balloon_page_insert(struct balloon_dev_info *balloon, struct page *page) { - __SetPageBalloon(page); + __SetPageOffline(page); __SetPageMovable(page, balloon->inode->i_mapping); set_page_private(page, (unsigned long)balloon); list_add(&page->lru, &balloon->pages); @@ -119,7 +111,7 @@ static inline void balloon_page_insert(struct balloon_dev_info *balloon, */ static inline void balloon_page_delete(struct page *page) { - __ClearPageBalloon(page); + __ClearPageOffline(page); __ClearPageMovable(page); set_page_private(page, 0); /* @@ -149,13 +141,13 @@ 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); + __SetPageOffline(page); list_add(&page->lru, &balloon->pages); } static inline void balloon_page_delete(struct page *page) { - __ClearPageBalloon(page); + __ClearPageOffline(page); list_del(&page->lru); } |