Commit | Line | Data |
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18468d93 RA |
1 | /* |
2 | * mm/balloon_compaction.c | |
3 | * | |
4 | * Common interface for making balloon pages movable by compaction. | |
5 | * | |
6 | * Copyright (C) 2012, Red Hat, Inc. Rafael Aquini <aquini@redhat.com> | |
7 | */ | |
8 | #include <linux/mm.h> | |
9 | #include <linux/slab.h> | |
10 | #include <linux/export.h> | |
11 | #include <linux/balloon_compaction.h> | |
12 | ||
c7cdff0e MT |
13 | /* |
14 | * balloon_page_alloc - allocates a new page for insertion into the balloon | |
15 | * page list. | |
16 | * | |
17 | * Driver must call it to properly allocate a new enlisted balloon page. | |
18 | * Driver must call balloon_page_enqueue before definitively removing it from | |
19 | * the guest system. This function returns the page address for the recently | |
20 | * allocated page or NULL in the case we fail to allocate a new page this turn. | |
21 | */ | |
22 | struct page *balloon_page_alloc(void) | |
23 | { | |
24 | struct page *page = alloc_page(balloon_mapping_gfp_mask() | | |
25 | __GFP_NOMEMALLOC | __GFP_NORETRY); | |
26 | return page; | |
27 | } | |
28 | EXPORT_SYMBOL_GPL(balloon_page_alloc); | |
29 | ||
18468d93 RA |
30 | /* |
31 | * balloon_page_enqueue - allocates a new page and inserts it into the balloon | |
32 | * page list. | |
bdb428c8 | 33 | * @b_dev_info: balloon device descriptor where we will insert a new page to |
c7cdff0e | 34 | * @page: new page to enqueue - allocated using balloon_page_alloc. |
18468d93 | 35 | * |
c7cdff0e | 36 | * Driver must call it to properly enqueue a new allocated balloon page |
bdb428c8 | 37 | * before definitively removing it from the guest system. |
18468d93 RA |
38 | * This function returns the page address for the recently enqueued page or |
39 | * NULL in the case we fail to allocate a new page this turn. | |
40 | */ | |
c7cdff0e MT |
41 | void balloon_page_enqueue(struct balloon_dev_info *b_dev_info, |
42 | struct page *page) | |
18468d93 RA |
43 | { |
44 | unsigned long flags; | |
18468d93 RA |
45 | |
46 | /* | |
47 | * Block others from accessing the 'page' when we get around to | |
48 | * establishing additional references. We should be the only one | |
49 | * holding a reference to the 'page' at this point. | |
50 | */ | |
51 | BUG_ON(!trylock_page(page)); | |
52 | spin_lock_irqsave(&b_dev_info->pages_lock, flags); | |
9d1ba805 | 53 | balloon_page_insert(b_dev_info, page); |
09316c09 | 54 | __count_vm_event(BALLOON_INFLATE); |
18468d93 RA |
55 | spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); |
56 | unlock_page(page); | |
18468d93 RA |
57 | } |
58 | EXPORT_SYMBOL_GPL(balloon_page_enqueue); | |
59 | ||
60 | /* | |
61 | * balloon_page_dequeue - removes a page from balloon's page list and returns | |
62 | * the its address to allow the driver release the page. | |
63 | * @b_dev_info: balloon device decriptor where we will grab a page from. | |
64 | * | |
65 | * Driver must call it to properly de-allocate a previous enlisted balloon page | |
66 | * before definetively releasing it back to the guest system. | |
67 | * This function returns the page address for the recently dequeued page or | |
68 | * NULL in the case we find balloon's page list temporarily empty due to | |
69 | * compaction isolated pages. | |
70 | */ | |
71 | struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info) | |
72 | { | |
73 | struct page *page, *tmp; | |
74 | unsigned long flags; | |
75 | bool dequeued_page; | |
76 | ||
77 | dequeued_page = false; | |
21ea9fb6 | 78 | spin_lock_irqsave(&b_dev_info->pages_lock, flags); |
18468d93 RA |
79 | list_for_each_entry_safe(page, tmp, &b_dev_info->pages, lru) { |
80 | /* | |
81 | * Block others from accessing the 'page' while we get around | |
82 | * establishing additional references and preparing the 'page' | |
83 | * to be released by the balloon driver. | |
84 | */ | |
85 | if (trylock_page(page)) { | |
4d88e6f7 | 86 | #ifdef CONFIG_BALLOON_COMPACTION |
b1123ea6 | 87 | if (PageIsolated(page)) { |
d6d86c0a KK |
88 | /* raced with isolation */ |
89 | unlock_page(page); | |
90 | continue; | |
91 | } | |
4d88e6f7 | 92 | #endif |
18468d93 | 93 | balloon_page_delete(page); |
09316c09 | 94 | __count_vm_event(BALLOON_DEFLATE); |
18468d93 RA |
95 | unlock_page(page); |
96 | dequeued_page = true; | |
97 | break; | |
98 | } | |
99 | } | |
21ea9fb6 | 100 | spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); |
18468d93 RA |
101 | |
102 | if (!dequeued_page) { | |
103 | /* | |
104 | * If we are unable to dequeue a balloon page because the page | |
105 | * list is empty and there is no isolated pages, then something | |
106 | * went out of track and some balloon pages are lost. | |
107 | * BUG() here, otherwise the balloon driver may get stuck into | |
108 | * an infinite loop while attempting to release all its pages. | |
109 | */ | |
110 | spin_lock_irqsave(&b_dev_info->pages_lock, flags); | |
111 | if (unlikely(list_empty(&b_dev_info->pages) && | |
112 | !b_dev_info->isolated_pages)) | |
113 | BUG(); | |
114 | spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); | |
115 | page = NULL; | |
116 | } | |
117 | return page; | |
118 | } | |
119 | EXPORT_SYMBOL_GPL(balloon_page_dequeue); | |
120 | ||
121 | #ifdef CONFIG_BALLOON_COMPACTION | |
18468d93 | 122 | |
b1123ea6 MK |
123 | bool balloon_page_isolate(struct page *page, isolate_mode_t mode) |
124 | ||
18468d93 | 125 | { |
9d1ba805 | 126 | struct balloon_dev_info *b_dev_info = balloon_page_device(page); |
18468d93 | 127 | unsigned long flags; |
d6d86c0a | 128 | |
18468d93 RA |
129 | spin_lock_irqsave(&b_dev_info->pages_lock, flags); |
130 | list_del(&page->lru); | |
131 | b_dev_info->isolated_pages++; | |
132 | spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); | |
b1123ea6 MK |
133 | |
134 | return true; | |
18468d93 RA |
135 | } |
136 | ||
b1123ea6 | 137 | void balloon_page_putback(struct page *page) |
18468d93 | 138 | { |
9d1ba805 | 139 | struct balloon_dev_info *b_dev_info = balloon_page_device(page); |
18468d93 | 140 | unsigned long flags; |
d6d86c0a | 141 | |
18468d93 RA |
142 | spin_lock_irqsave(&b_dev_info->pages_lock, flags); |
143 | list_add(&page->lru, &b_dev_info->pages); | |
144 | b_dev_info->isolated_pages--; | |
145 | spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); | |
146 | } | |
147 | ||
18468d93 RA |
148 | |
149 | /* move_to_new_page() counterpart for a ballooned page */ | |
b1123ea6 MK |
150 | int balloon_page_migrate(struct address_space *mapping, |
151 | struct page *newpage, struct page *page, | |
152 | enum migrate_mode mode) | |
18468d93 | 153 | { |
9d1ba805 | 154 | struct balloon_dev_info *balloon = balloon_page_device(page); |
18468d93 | 155 | |
2916ecc0 JG |
156 | /* |
157 | * We can not easily support the no copy case here so ignore it as it | |
158 | * is unlikely to be use with ballon pages. See include/linux/hmm.h for | |
159 | * user of the MIGRATE_SYNC_NO_COPY mode. | |
160 | */ | |
161 | if (mode == MIGRATE_SYNC_NO_COPY) | |
162 | return -EINVAL; | |
163 | ||
7db7671f HD |
164 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
165 | VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); | |
18468d93 | 166 | |
b1123ea6 MK |
167 | return balloon->migratepage(balloon, newpage, page, mode); |
168 | } | |
18468d93 | 169 | |
b1123ea6 MK |
170 | const struct address_space_operations balloon_aops = { |
171 | .migratepage = balloon_page_migrate, | |
172 | .isolate_page = balloon_page_isolate, | |
173 | .putback_page = balloon_page_putback, | |
174 | }; | |
175 | EXPORT_SYMBOL_GPL(balloon_aops); | |
18468d93 | 176 | |
18468d93 | 177 | #endif /* CONFIG_BALLOON_COMPACTION */ |