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 | ||
18468d93 RA |
13 | /* |
14 | * balloon_page_enqueue - allocates a new page and inserts it into the balloon | |
15 | * page list. | |
bdb428c8 | 16 | * @b_dev_info: balloon device descriptor where we will insert a new page to |
18468d93 RA |
17 | * |
18 | * Driver must call it to properly allocate a new enlisted balloon page | |
bdb428c8 | 19 | * before definitively removing it from the guest system. |
18468d93 RA |
20 | * This function returns the page address for the recently enqueued page or |
21 | * NULL in the case we fail to allocate a new page this turn. | |
22 | */ | |
23 | struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info) | |
24 | { | |
25 | unsigned long flags; | |
26 | struct page *page = alloc_page(balloon_mapping_gfp_mask() | | |
af54aed9 | 27 | __GFP_NOMEMALLOC | __GFP_NORETRY); |
18468d93 RA |
28 | if (!page) |
29 | return NULL; | |
30 | ||
31 | /* | |
32 | * Block others from accessing the 'page' when we get around to | |
33 | * establishing additional references. We should be the only one | |
34 | * holding a reference to the 'page' at this point. | |
35 | */ | |
36 | BUG_ON(!trylock_page(page)); | |
37 | spin_lock_irqsave(&b_dev_info->pages_lock, flags); | |
9d1ba805 | 38 | balloon_page_insert(b_dev_info, page); |
09316c09 | 39 | __count_vm_event(BALLOON_INFLATE); |
18468d93 RA |
40 | spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); |
41 | unlock_page(page); | |
42 | return page; | |
43 | } | |
44 | EXPORT_SYMBOL_GPL(balloon_page_enqueue); | |
45 | ||
46 | /* | |
47 | * balloon_page_dequeue - removes a page from balloon's page list and returns | |
48 | * the its address to allow the driver release the page. | |
49 | * @b_dev_info: balloon device decriptor where we will grab a page from. | |
50 | * | |
51 | * Driver must call it to properly de-allocate a previous enlisted balloon page | |
52 | * before definetively releasing it back to the guest system. | |
53 | * This function returns the page address for the recently dequeued page or | |
54 | * NULL in the case we find balloon's page list temporarily empty due to | |
55 | * compaction isolated pages. | |
56 | */ | |
57 | struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info) | |
58 | { | |
59 | struct page *page, *tmp; | |
60 | unsigned long flags; | |
61 | bool dequeued_page; | |
62 | ||
63 | dequeued_page = false; | |
21ea9fb6 | 64 | spin_lock_irqsave(&b_dev_info->pages_lock, flags); |
18468d93 RA |
65 | list_for_each_entry_safe(page, tmp, &b_dev_info->pages, lru) { |
66 | /* | |
67 | * Block others from accessing the 'page' while we get around | |
68 | * establishing additional references and preparing the 'page' | |
69 | * to be released by the balloon driver. | |
70 | */ | |
71 | if (trylock_page(page)) { | |
4d88e6f7 | 72 | #ifdef CONFIG_BALLOON_COMPACTION |
b1123ea6 | 73 | if (PageIsolated(page)) { |
d6d86c0a KK |
74 | /* raced with isolation */ |
75 | unlock_page(page); | |
76 | continue; | |
77 | } | |
4d88e6f7 | 78 | #endif |
18468d93 | 79 | balloon_page_delete(page); |
09316c09 | 80 | __count_vm_event(BALLOON_DEFLATE); |
18468d93 RA |
81 | unlock_page(page); |
82 | dequeued_page = true; | |
83 | break; | |
84 | } | |
85 | } | |
21ea9fb6 | 86 | spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); |
18468d93 RA |
87 | |
88 | if (!dequeued_page) { | |
89 | /* | |
90 | * If we are unable to dequeue a balloon page because the page | |
91 | * list is empty and there is no isolated pages, then something | |
92 | * went out of track and some balloon pages are lost. | |
93 | * BUG() here, otherwise the balloon driver may get stuck into | |
94 | * an infinite loop while attempting to release all its pages. | |
95 | */ | |
96 | spin_lock_irqsave(&b_dev_info->pages_lock, flags); | |
97 | if (unlikely(list_empty(&b_dev_info->pages) && | |
98 | !b_dev_info->isolated_pages)) | |
99 | BUG(); | |
100 | spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); | |
101 | page = NULL; | |
102 | } | |
103 | return page; | |
104 | } | |
105 | EXPORT_SYMBOL_GPL(balloon_page_dequeue); | |
106 | ||
107 | #ifdef CONFIG_BALLOON_COMPACTION | |
18468d93 | 108 | |
b1123ea6 MK |
109 | bool balloon_page_isolate(struct page *page, isolate_mode_t mode) |
110 | ||
18468d93 | 111 | { |
9d1ba805 | 112 | struct balloon_dev_info *b_dev_info = balloon_page_device(page); |
18468d93 | 113 | unsigned long flags; |
d6d86c0a | 114 | |
18468d93 RA |
115 | spin_lock_irqsave(&b_dev_info->pages_lock, flags); |
116 | list_del(&page->lru); | |
117 | b_dev_info->isolated_pages++; | |
118 | spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); | |
b1123ea6 MK |
119 | |
120 | return true; | |
18468d93 RA |
121 | } |
122 | ||
b1123ea6 | 123 | void balloon_page_putback(struct page *page) |
18468d93 | 124 | { |
9d1ba805 | 125 | struct balloon_dev_info *b_dev_info = balloon_page_device(page); |
18468d93 | 126 | unsigned long flags; |
d6d86c0a | 127 | |
18468d93 RA |
128 | spin_lock_irqsave(&b_dev_info->pages_lock, flags); |
129 | list_add(&page->lru, &b_dev_info->pages); | |
130 | b_dev_info->isolated_pages--; | |
131 | spin_unlock_irqrestore(&b_dev_info->pages_lock, flags); | |
132 | } | |
133 | ||
18468d93 RA |
134 | |
135 | /* move_to_new_page() counterpart for a ballooned page */ | |
b1123ea6 MK |
136 | int balloon_page_migrate(struct address_space *mapping, |
137 | struct page *newpage, struct page *page, | |
138 | enum migrate_mode mode) | |
18468d93 | 139 | { |
9d1ba805 | 140 | struct balloon_dev_info *balloon = balloon_page_device(page); |
18468d93 | 141 | |
2916ecc0 JG |
142 | /* |
143 | * We can not easily support the no copy case here so ignore it as it | |
144 | * is unlikely to be use with ballon pages. See include/linux/hmm.h for | |
145 | * user of the MIGRATE_SYNC_NO_COPY mode. | |
146 | */ | |
147 | if (mode == MIGRATE_SYNC_NO_COPY) | |
148 | return -EINVAL; | |
149 | ||
7db7671f HD |
150 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
151 | VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); | |
18468d93 | 152 | |
b1123ea6 MK |
153 | return balloon->migratepage(balloon, newpage, page, mode); |
154 | } | |
18468d93 | 155 | |
b1123ea6 MK |
156 | const struct address_space_operations balloon_aops = { |
157 | .migratepage = balloon_page_migrate, | |
158 | .isolate_page = balloon_page_isolate, | |
159 | .putback_page = balloon_page_putback, | |
160 | }; | |
161 | EXPORT_SYMBOL_GPL(balloon_aops); | |
18468d93 | 162 | |
18468d93 | 163 | #endif /* CONFIG_BALLOON_COMPACTION */ |