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Diffstat (limited to 'include/linux/balloon.h')
| -rw-r--r-- | include/linux/balloon.h | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/include/linux/balloon.h b/include/linux/balloon.h new file mode 100644 index 000000000000..ca5b15150f42 --- /dev/null +++ b/include/linux/balloon.h @@ -0,0 +1,77 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Common interface for implementing a memory balloon, including support + * for migration of pages inflated in a memory balloon. + * + * Balloon page migration makes use of the general "movable_ops page migration" + * feature. + * + * page->private is used to reference the responsible balloon device. + * That these pages have movable_ops, and which movable_ops apply, + * is derived from the page type (PageOffline()) combined with the + * PG_movable_ops flag (PageMovableOps()). + * + * Once the page type and the PG_movable_ops are set, migration code + * can initiate page isolation by invoking the + * movable_operations()->isolate_page() callback + * + * As long as page->private is set, the page is either on the balloon list + * or isolated for migration. If page->private is not set, the page is + * either still getting inflated, or was deflated to be freed by the balloon + * driver soon. Isolation is impossible in both cases. + * + * 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 migration. In order to sort out these racy scenarios + * and safely perform balloon's page migration we must, always, ensure following + * these simple rules: + * + * i. Inflation/deflation must set/clear page->private under the + * balloon_pages_lock + * + * ii. isolation or dequeueing procedure must remove the page from balloon + * device page list under balloon_pages_lock + * + * Copyright (C) 2012, Red Hat, Inc. Rafael Aquini <aquini@redhat.com> + */ +#ifndef _LINUX_BALLOON_H +#define _LINUX_BALLOON_H +#include <linux/pagemap.h> +#include <linux/page-flags.h> +#include <linux/migrate.h> +#include <linux/gfp.h> +#include <linux/err.h> +#include <linux/list.h> + +/* + * Balloon device information descriptor. + * This struct is used to allow the common balloon page migration interface + * procedures to find the proper balloon device holding memory pages they'll + * have to cope for page migration, as well as it serves the balloon driver as + * a page book-keeper for its registered balloon devices. + */ +struct balloon_dev_info { + unsigned long isolated_pages; /* # of isolated pages for migration */ + 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); + bool adjust_managed_page_count; +}; + +struct page *balloon_page_alloc(void); +void balloon_page_enqueue(struct balloon_dev_info *b_dev_info, + struct page *page); +struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info); +size_t balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info, + struct list_head *pages); +size_t balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info, + struct list_head *pages, size_t n_req_pages); + +static inline void balloon_devinfo_init(struct balloon_dev_info *balloon) +{ + balloon->isolated_pages = 0; + INIT_LIST_HEAD(&balloon->pages); + balloon->migratepage = NULL; + balloon->adjust_managed_page_count = false; +} +#endif /* _LINUX_BALLOON_H */ |