cregit-Linux how code gets into the kernel

Release 4.7 include/linux/balloon_compaction.h

Directory: include/linux
/*
 * include/linux/balloon_compaction.h
 *
 * 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.
 *
 * 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:
 *
 *   i. when updating a balloon's page ->mapping element, strictly do it under
 *      the following lock order, independently of the far superior
 *      locking scheme (lru_lock, balloon_lock):
 *          +-page_lock(page);
 *            +--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.
 *
 * 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
 * compaction / migration.
 *
 * Copyright (C) 2012, Red Hat, Inc.  Rafael Aquini <aquini@redhat.com>
 */
#ifndef _LINUX_BALLOON_COMPACTION_H

#define _LINUX_BALLOON_COMPACTION_H
#include <linux/pagemap.h>
#include <linux/page-flags.h>
#include <linux/migrate.h>
#include <linux/gfp.h>
#include <linux/err.h>

/*
 * Balloon device information descriptor.
 * This struct is used to allow the common balloon compaction interface
 * procedures to find the proper balloon device holding memory pages they'll
 * have to cope for page compaction / 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 */
	
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);


static inline void balloon_devinfo_init(struct balloon_dev_info *balloon) { balloon->isolated_pages = 0; spin_lock_init(&balloon->pages_lock); INIT_LIST_HEAD(&balloon->pages); balloon->migratepage = NULL; }

Contributors

PersonTokensPropCommitsCommitProp
konstantin khlebnikovkonstantin khlebnikov2767.50%150.00%
rafael aquinirafael aquini1332.50%150.00%
Total40100.00%2100.00%

#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); /* * __is_movable_balloon_page - helper to perform @page PageBalloon tests */
static inline bool __is_movable_balloon_page(struct page *page) { return PageBalloon(page); }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini1688.89%150.00%
konstantin khlebnikovkonstantin khlebnikov211.11%150.00%
Total18100.00%2100.00%

/* * 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, this need to be re-tested later, under the page lock. */
static inline bool balloon_page_movable(struct page *page) { return PageBalloon(page) && PagePrivate(page); }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini2086.96%150.00%
konstantin khlebnikovkonstantin khlebnikov313.04%150.00%
Total23100.00%2100.00%

/* * isolated_balloon_page - identify an isolated balloon page on private * compaction/migration page lists. */
static inline bool isolated_balloon_page(struct page *page) { return PageBalloon(page); }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini1794.44%150.00%
konstantin khlebnikovkonstantin khlebnikov15.56%150.00%
Total18100.00%2100.00%

/* * balloon_page_insert - insert a page into the balloon's page list and make * the page->private assignment accordingly. * @balloon : pointer to balloon 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 balloon_dev_info *balloon, struct page *page) { __SetPageBalloon(page); SetPagePrivate(page); set_page_private(page, (unsigned long)balloon); list_add(&page->lru, &balloon->pages); }

Contributors

PersonTokensPropCommitsCommitProp
konstantin khlebnikovkonstantin khlebnikov2752.94%266.67%
rafael aquinirafael aquini2447.06%133.33%
Total51100.00%3100.00%

/* * balloon_page_delete - delete a page from balloon's page list and clear * the page->private assignement accordingly. * @page : page to be released from balloon's page 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) { __ClearPageBalloon(page); set_page_private(page, 0); if (PagePrivate(page)) { ClearPagePrivate(page); list_del(&page->lru); } }

Contributors

PersonTokensPropCommitsCommitProp
konstantin khlebnikovkonstantin khlebnikov2452.17%266.67%
rafael aquinirafael aquini2247.83%133.33%
Total46100.00%3100.00%

/* * balloon_page_device - get the b_dev_info descriptor for the balloon device * that enqueues the given page. */
static inline struct balloon_dev_info *balloon_page_device(struct page *page) { return (struct balloon_dev_info *)page_private(page); }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini1768.00%150.00%
konstantin khlebnikovkonstantin khlebnikov832.00%150.00%
Total25100.00%2100.00%


static inline gfp_t balloon_mapping_gfp_mask(void) { return GFP_HIGHUSER_MOVABLE; }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini12100.00%1100.00%
Total12100.00%1100.00%

#else /* !CONFIG_BALLOON_COMPACTION */
static inline void balloon_page_insert(struct balloon_dev_info *balloon, struct page *page) { __SetPageBalloon(page); list_add(&page->lru, &balloon->pages); }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini2262.86%133.33%
konstantin khlebnikovkonstantin khlebnikov1337.14%266.67%
Total35100.00%3100.00%


static inline void balloon_page_delete(struct page *page) { __ClearPageBalloon(page); list_del(&page->lru); }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini2080.00%150.00%
konstantin khlebnikovkonstantin khlebnikov520.00%150.00%
Total25100.00%2100.00%


static inline bool __is_movable_balloon_page(struct page *page) { return false; }

Contributors

PersonTokensPropCommitsCommitProp
konstantin khlebnikovkonstantin khlebnikov15100.00%1100.00%
Total15100.00%1100.00%


static inline bool balloon_page_movable(struct page *page) { return false; }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini15100.00%1100.00%
Total15100.00%1100.00%


static inline bool isolated_balloon_page(struct page *page) { return false; }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini15100.00%1100.00%
Total15100.00%1100.00%


static inline bool balloon_page_isolate(struct page *page) { return false; }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini15100.00%1100.00%
Total15100.00%1100.00%


static inline void balloon_page_putback(struct page *page) { return; }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini13100.00%1100.00%
Total13100.00%1100.00%


static inline int balloon_page_migrate(struct page *newpage, struct page *page, enum migrate_mode mode) { return 0; }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini24100.00%1100.00%
Total24100.00%1100.00%


static inline gfp_t balloon_mapping_gfp_mask(void) { return GFP_HIGHUSER; }

Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini12100.00%1100.00%
Total12100.00%1100.00%

#endif /* CONFIG_BALLOON_COMPACTION */ #endif /* _LINUX_BALLOON_COMPACTION_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
rafael aquinirafael aquini39471.64%240.00%
konstantin khlebnikovkonstantin khlebnikov15628.36%360.00%
Total550100.00%5100.00%
Directory: include/linux
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
{% endraw %}