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210 lines
6.6 KiB
210 lines
6.6 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* |
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* include/linux/balloon_compaction.h |
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* |
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* Common interface definitions for making balloon pages movable by compaction. |
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* |
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* Balloon page migration makes use of the general non-lru movable page |
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* feature. |
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* |
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* page->private is used to reference the responsible balloon device. |
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* page->mapping is used in context of non-lru page migration to reference |
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* the address space operations for page isolation/migration/compaction. |
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* |
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* As the page isolation scanning step a compaction thread does is a lockless |
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* procedure (from a page standpoint), it might bring some racy situations while |
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* performing balloon page compaction. In order to sort out these racy scenarios |
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* and safely perform balloon's page compaction and migration we must, always, |
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* ensure following these simple rules: |
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* |
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* i. when updating a balloon's page ->mapping element, strictly do it under |
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* the following lock order, independently of the far superior |
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* locking scheme (lru_lock, balloon_lock): |
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* +-page_lock(page); |
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* +--spin_lock_irq(&b_dev_info->pages_lock); |
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* ... page->mapping updates here ... |
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* |
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* ii. isolation or dequeueing procedure must remove the page from balloon |
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* device page list under b_dev_info->pages_lock. |
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* |
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* The functions provided by this interface are placed to help on coping with |
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* the aforementioned balloon page corner case, as well as to ensure the simple |
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* set of exposed rules are satisfied while we are dealing with balloon pages |
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* compaction / migration. |
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* |
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* Copyright (C) 2012, Red Hat, Inc. Rafael Aquini <[email protected]> |
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*/ |
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#ifndef _LINUX_BALLOON_COMPACTION_H |
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#define _LINUX_BALLOON_COMPACTION_H |
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#include <linux/pagemap.h> |
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#include <linux/page-flags.h> |
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#include <linux/migrate.h> |
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#include <linux/gfp.h> |
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#include <linux/err.h> |
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#include <linux/fs.h> |
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#include <linux/list.h> |
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/* |
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* Balloon device information descriptor. |
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* This struct is used to allow the common balloon compaction interface |
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* procedures to find the proper balloon device holding memory pages they'll |
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* have to cope for page compaction / migration, as well as it serves the |
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* balloon driver as a page book-keeper for its registered balloon devices. |
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*/ |
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struct balloon_dev_info { |
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unsigned long isolated_pages; /* # of isolated pages for migration */ |
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spinlock_t pages_lock; /* Protection to pages list */ |
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struct list_head pages; /* Pages enqueued & handled to Host */ |
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int (*migratepage)(struct balloon_dev_info *, struct page *newpage, |
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struct page *page, enum migrate_mode mode); |
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struct inode *inode; |
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}; |
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extern struct page *balloon_page_alloc(void); |
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extern void balloon_page_enqueue(struct balloon_dev_info *b_dev_info, |
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struct page *page); |
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extern struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info); |
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extern size_t balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info, |
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struct list_head *pages); |
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extern size_t balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info, |
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struct list_head *pages, size_t n_req_pages); |
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static inline void balloon_devinfo_init(struct balloon_dev_info *balloon) |
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{ |
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balloon->isolated_pages = 0; |
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spin_lock_init(&balloon->pages_lock); |
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INIT_LIST_HEAD(&balloon->pages); |
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balloon->migratepage = NULL; |
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balloon->inode = NULL; |
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} |
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#ifdef CONFIG_BALLOON_COMPACTION |
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extern const struct address_space_operations balloon_aops; |
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extern bool balloon_page_isolate(struct page *page, |
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isolate_mode_t mode); |
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extern void balloon_page_putback(struct page *page); |
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extern int balloon_page_migrate(struct address_space *mapping, |
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struct page *newpage, |
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struct page *page, enum migrate_mode mode); |
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/* |
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* balloon_page_insert - insert a page into the balloon's page list and make |
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* the page->private assignment accordingly. |
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* @balloon : pointer to balloon device |
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* @page : page to be assigned as a 'balloon page' |
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* |
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* Caller must ensure the page is locked and the spin_lock protecting balloon |
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* pages list is held before inserting a page into the balloon device. |
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*/ |
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static inline void balloon_page_insert(struct balloon_dev_info *balloon, |
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struct page *page) |
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{ |
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__SetPageOffline(page); |
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__SetPageMovable(page, balloon->inode->i_mapping); |
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set_page_private(page, (unsigned long)balloon); |
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list_add(&page->lru, &balloon->pages); |
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} |
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/* |
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* balloon_page_delete - delete a page from balloon's page list and clear |
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* the page->private assignement accordingly. |
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* @page : page to be released from balloon's page list |
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* |
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* Caller must ensure the page is locked and the spin_lock protecting balloon |
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* pages list is held before deleting a page from the balloon device. |
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*/ |
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static inline void balloon_page_delete(struct page *page) |
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{ |
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__ClearPageOffline(page); |
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__ClearPageMovable(page); |
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set_page_private(page, 0); |
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/* |
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* No touch page.lru field once @page has been isolated |
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* because VM is using the field. |
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*/ |
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if (!PageIsolated(page)) |
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list_del(&page->lru); |
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} |
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/* |
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* balloon_page_device - get the b_dev_info descriptor for the balloon device |
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* that enqueues the given page. |
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*/ |
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static inline struct balloon_dev_info *balloon_page_device(struct page *page) |
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{ |
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return (struct balloon_dev_info *)page_private(page); |
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} |
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static inline gfp_t balloon_mapping_gfp_mask(void) |
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{ |
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return GFP_HIGHUSER_MOVABLE; |
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} |
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#else /* !CONFIG_BALLOON_COMPACTION */ |
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static inline void balloon_page_insert(struct balloon_dev_info *balloon, |
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struct page *page) |
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{ |
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__SetPageOffline(page); |
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list_add(&page->lru, &balloon->pages); |
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} |
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static inline void balloon_page_delete(struct page *page) |
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{ |
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__ClearPageOffline(page); |
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list_del(&page->lru); |
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} |
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static inline bool balloon_page_isolate(struct page *page) |
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{ |
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return false; |
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} |
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static inline void balloon_page_putback(struct page *page) |
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{ |
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return; |
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} |
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static inline int balloon_page_migrate(struct page *newpage, |
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struct page *page, enum migrate_mode mode) |
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{ |
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return 0; |
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} |
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static inline gfp_t balloon_mapping_gfp_mask(void) |
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{ |
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return GFP_HIGHUSER; |
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} |
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#endif /* CONFIG_BALLOON_COMPACTION */ |
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/* |
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* balloon_page_push - insert a page into a page list. |
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* @head : pointer to list |
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* @page : page to be added |
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* |
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* Caller must ensure the page is private and protect the list. |
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*/ |
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static inline void balloon_page_push(struct list_head *pages, struct page *page) |
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{ |
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list_add(&page->lru, pages); |
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} |
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/* |
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* balloon_page_pop - remove a page from a page list. |
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* @head : pointer to list |
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* @page : page to be added |
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* |
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* Caller must ensure the page is private and protect the list. |
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*/ |
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static inline struct page *balloon_page_pop(struct list_head *pages) |
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{ |
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struct page *page = list_first_entry_or_null(pages, struct page, lru); |
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if (!page) |
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return NULL; |
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list_del(&page->lru); |
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return page; |
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} |
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#endif /* _LINUX_BALLOON_COMPACTION_H */
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