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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
18468d93 RA |
2 | /* |
3 | * include/linux/balloon_compaction.h | |
4 | * | |
5 | * Common interface definitions for making balloon pages movable by compaction. | |
6 | * | |
4d3467e1 DH |
7 | * Balloon page migration makes use of the general non-lru movable page |
8 | * feature. | |
9 | * | |
10 | * page->private is used to reference the responsible balloon device. | |
11 | * page->mapping is used in context of non-lru page migration to reference | |
12 | * the address space operations for page isolation/migration/compaction. | |
18468d93 RA |
13 | * |
14 | * As the page isolation scanning step a compaction thread does is a lockless | |
15 | * procedure (from a page standpoint), it might bring some racy situations while | |
16 | * performing balloon page compaction. In order to sort out these racy scenarios | |
17 | * and safely perform balloon's page compaction and migration we must, always, | |
4d3467e1 | 18 | * ensure following these simple rules: |
18468d93 RA |
19 | * |
20 | * i. when updating a balloon's page ->mapping element, strictly do it under | |
21 | * the following lock order, independently of the far superior | |
22 | * locking scheme (lru_lock, balloon_lock): | |
23 | * +-page_lock(page); | |
24 | * +--spin_lock_irq(&b_dev_info->pages_lock); | |
25 | * ... page->mapping updates here ... | |
26 | * | |
4d3467e1 DH |
27 | * ii. isolation or dequeueing procedure must remove the page from balloon |
28 | * device page list under b_dev_info->pages_lock. | |
d6d86c0a | 29 | * |
18468d93 RA |
30 | * The functions provided by this interface are placed to help on coping with |
31 | * the aforementioned balloon page corner case, as well as to ensure the simple | |
32 | * set of exposed rules are satisfied while we are dealing with balloon pages | |
33 | * compaction / migration. | |
34 | * | |
35 | * Copyright (C) 2012, Red Hat, Inc. Rafael Aquini <aquini@redhat.com> | |
36 | */ | |
37 | #ifndef _LINUX_BALLOON_COMPACTION_H | |
38 | #define _LINUX_BALLOON_COMPACTION_H | |
39 | #include <linux/pagemap.h> | |
40 | #include <linux/page-flags.h> | |
dd4123f3 | 41 | #include <linux/migrate.h> |
18468d93 RA |
42 | #include <linux/gfp.h> |
43 | #include <linux/err.h> | |
b1123ea6 | 44 | #include <linux/fs.h> |
c7cdff0e | 45 | #include <linux/list.h> |
18468d93 RA |
46 | |
47 | /* | |
48 | * Balloon device information descriptor. | |
49 | * This struct is used to allow the common balloon compaction interface | |
50 | * procedures to find the proper balloon device holding memory pages they'll | |
51 | * have to cope for page compaction / migration, as well as it serves the | |
52 | * balloon driver as a page book-keeper for its registered balloon devices. | |
53 | */ | |
54 | struct balloon_dev_info { | |
18468d93 RA |
55 | unsigned long isolated_pages; /* # of isolated pages for migration */ |
56 | spinlock_t pages_lock; /* Protection to pages list */ | |
57 | struct list_head pages; /* Pages enqueued & handled to Host */ | |
9d1ba805 KK |
58 | int (*migratepage)(struct balloon_dev_info *, struct page *newpage, |
59 | struct page *page, enum migrate_mode mode); | |
b1123ea6 | 60 | struct inode *inode; |
18468d93 RA |
61 | }; |
62 | ||
c7cdff0e MT |
63 | extern struct page *balloon_page_alloc(void); |
64 | extern void balloon_page_enqueue(struct balloon_dev_info *b_dev_info, | |
65 | struct page *page); | |
18468d93 | 66 | extern struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info); |
418a3ab1 NA |
67 | extern size_t balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info, |
68 | struct list_head *pages); | |
69 | extern size_t balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info, | |
70 | struct list_head *pages, size_t n_req_pages); | |
18468d93 | 71 | |
9d1ba805 | 72 | static inline void balloon_devinfo_init(struct balloon_dev_info *balloon) |
18468d93 | 73 | { |
9d1ba805 KK |
74 | balloon->isolated_pages = 0; |
75 | spin_lock_init(&balloon->pages_lock); | |
76 | INIT_LIST_HEAD(&balloon->pages); | |
77 | balloon->migratepage = NULL; | |
b1123ea6 | 78 | balloon->inode = NULL; |
18468d93 RA |
79 | } |
80 | ||
18468d93 | 81 | #ifdef CONFIG_BALLOON_COMPACTION |
b1123ea6 MK |
82 | extern const struct address_space_operations balloon_aops; |
83 | extern bool balloon_page_isolate(struct page *page, | |
84 | isolate_mode_t mode); | |
18468d93 | 85 | extern void balloon_page_putback(struct page *page); |
b1123ea6 MK |
86 | extern int balloon_page_migrate(struct address_space *mapping, |
87 | struct page *newpage, | |
18468d93 | 88 | struct page *page, enum migrate_mode mode); |
18468d93 | 89 | |
18468d93 RA |
90 | /* |
91 | * balloon_page_insert - insert a page into the balloon's page list and make | |
9d1ba805 KK |
92 | * the page->private assignment accordingly. |
93 | * @balloon : pointer to balloon device | |
18468d93 | 94 | * @page : page to be assigned as a 'balloon page' |
18468d93 RA |
95 | * |
96 | * Caller must ensure the page is locked and the spin_lock protecting balloon | |
97 | * pages list is held before inserting a page into the balloon device. | |
98 | */ | |
9d1ba805 KK |
99 | static inline void balloon_page_insert(struct balloon_dev_info *balloon, |
100 | struct page *page) | |
18468d93 | 101 | { |
ca215086 | 102 | __SetPageOffline(page); |
b1123ea6 | 103 | __SetPageMovable(page, balloon->inode->i_mapping); |
9d1ba805 KK |
104 | set_page_private(page, (unsigned long)balloon); |
105 | list_add(&page->lru, &balloon->pages); | |
18468d93 RA |
106 | } |
107 | ||
108 | /* | |
109 | * balloon_page_delete - delete a page from balloon's page list and clear | |
9d1ba805 | 110 | * the page->private assignement accordingly. |
18468d93 RA |
111 | * @page : page to be released from balloon's page list |
112 | * | |
113 | * Caller must ensure the page is locked and the spin_lock protecting balloon | |
114 | * pages list is held before deleting a page from the balloon device. | |
115 | */ | |
116 | static inline void balloon_page_delete(struct page *page) | |
117 | { | |
ca215086 | 118 | __ClearPageOffline(page); |
b1123ea6 | 119 | __ClearPageMovable(page); |
9d1ba805 | 120 | set_page_private(page, 0); |
b1123ea6 MK |
121 | /* |
122 | * No touch page.lru field once @page has been isolated | |
123 | * because VM is using the field. | |
124 | */ | |
125 | if (!PageIsolated(page)) | |
d6d86c0a | 126 | list_del(&page->lru); |
18468d93 RA |
127 | } |
128 | ||
129 | /* | |
130 | * balloon_page_device - get the b_dev_info descriptor for the balloon device | |
131 | * that enqueues the given page. | |
132 | */ | |
133 | static inline struct balloon_dev_info *balloon_page_device(struct page *page) | |
134 | { | |
9d1ba805 | 135 | return (struct balloon_dev_info *)page_private(page); |
18468d93 RA |
136 | } |
137 | ||
138 | static inline gfp_t balloon_mapping_gfp_mask(void) | |
139 | { | |
140 | return GFP_HIGHUSER_MOVABLE; | |
141 | } | |
142 | ||
18468d93 RA |
143 | #else /* !CONFIG_BALLOON_COMPACTION */ |
144 | ||
9d1ba805 KK |
145 | static inline void balloon_page_insert(struct balloon_dev_info *balloon, |
146 | struct page *page) | |
18468d93 | 147 | { |
ca215086 | 148 | __SetPageOffline(page); |
9d1ba805 | 149 | list_add(&page->lru, &balloon->pages); |
18468d93 RA |
150 | } |
151 | ||
152 | static inline void balloon_page_delete(struct page *page) | |
153 | { | |
ca215086 | 154 | __ClearPageOffline(page); |
18468d93 RA |
155 | list_del(&page->lru); |
156 | } | |
157 | ||
18468d93 RA |
158 | static inline bool balloon_page_isolate(struct page *page) |
159 | { | |
160 | return false; | |
161 | } | |
162 | ||
163 | static inline void balloon_page_putback(struct page *page) | |
164 | { | |
165 | return; | |
166 | } | |
167 | ||
168 | static inline int balloon_page_migrate(struct page *newpage, | |
169 | struct page *page, enum migrate_mode mode) | |
170 | { | |
171 | return 0; | |
172 | } | |
173 | ||
174 | static inline gfp_t balloon_mapping_gfp_mask(void) | |
175 | { | |
176 | return GFP_HIGHUSER; | |
177 | } | |
178 | ||
18468d93 | 179 | #endif /* CONFIG_BALLOON_COMPACTION */ |
c7cdff0e MT |
180 | |
181 | /* | |
182 | * balloon_page_push - insert a page into a page list. | |
183 | * @head : pointer to list | |
184 | * @page : page to be added | |
185 | * | |
186 | * Caller must ensure the page is private and protect the list. | |
187 | */ | |
188 | static inline void balloon_page_push(struct list_head *pages, struct page *page) | |
189 | { | |
190 | list_add(&page->lru, pages); | |
191 | } | |
192 | ||
193 | /* | |
194 | * balloon_page_pop - remove a page from a page list. | |
195 | * @head : pointer to list | |
196 | * @page : page to be added | |
197 | * | |
198 | * Caller must ensure the page is private and protect the list. | |
199 | */ | |
200 | static inline struct page *balloon_page_pop(struct list_head *pages) | |
201 | { | |
202 | struct page *page = list_first_entry_or_null(pages, struct page, lru); | |
203 | ||
204 | if (!page) | |
205 | return NULL; | |
206 | ||
207 | list_del(&page->lru); | |
208 | return page; | |
209 | } | |
18468d93 | 210 | #endif /* _LINUX_BALLOON_COMPACTION_H */ |