Root/
1 | /* |
2 | * linux/mm/page_isolation.c |
3 | */ |
4 | |
5 | #include <linux/mm.h> |
6 | #include <linux/page-isolation.h> |
7 | #include <linux/pageblock-flags.h> |
8 | #include <linux/memory.h> |
9 | #include "internal.h" |
10 | |
11 | /* called while holding zone->lock */ |
12 | static void set_pageblock_isolate(struct page *page) |
13 | { |
14 | if (get_pageblock_migratetype(page) == MIGRATE_ISOLATE) |
15 | return; |
16 | |
17 | set_pageblock_migratetype(page, MIGRATE_ISOLATE); |
18 | page_zone(page)->nr_pageblock_isolate++; |
19 | } |
20 | |
21 | /* called while holding zone->lock */ |
22 | static void restore_pageblock_isolate(struct page *page, int migratetype) |
23 | { |
24 | struct zone *zone = page_zone(page); |
25 | if (WARN_ON(get_pageblock_migratetype(page) != MIGRATE_ISOLATE)) |
26 | return; |
27 | |
28 | BUG_ON(zone->nr_pageblock_isolate <= 0); |
29 | set_pageblock_migratetype(page, migratetype); |
30 | zone->nr_pageblock_isolate--; |
31 | } |
32 | |
33 | int set_migratetype_isolate(struct page *page) |
34 | { |
35 | struct zone *zone; |
36 | unsigned long flags, pfn; |
37 | struct memory_isolate_notify arg; |
38 | int notifier_ret; |
39 | int ret = -EBUSY; |
40 | |
41 | zone = page_zone(page); |
42 | |
43 | spin_lock_irqsave(&zone->lock, flags); |
44 | |
45 | pfn = page_to_pfn(page); |
46 | arg.start_pfn = pfn; |
47 | arg.nr_pages = pageblock_nr_pages; |
48 | arg.pages_found = 0; |
49 | |
50 | /* |
51 | * It may be possible to isolate a pageblock even if the |
52 | * migratetype is not MIGRATE_MOVABLE. The memory isolation |
53 | * notifier chain is used by balloon drivers to return the |
54 | * number of pages in a range that are held by the balloon |
55 | * driver to shrink memory. If all the pages are accounted for |
56 | * by balloons, are free, or on the LRU, isolation can continue. |
57 | * Later, for example, when memory hotplug notifier runs, these |
58 | * pages reported as "can be isolated" should be isolated(freed) |
59 | * by the balloon driver through the memory notifier chain. |
60 | */ |
61 | notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg); |
62 | notifier_ret = notifier_to_errno(notifier_ret); |
63 | if (notifier_ret) |
64 | goto out; |
65 | /* |
66 | * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. |
67 | * We just check MOVABLE pages. |
68 | */ |
69 | if (!has_unmovable_pages(zone, page, arg.pages_found)) |
70 | ret = 0; |
71 | |
72 | /* |
73 | * immobile means "not-on-lru" paes. If immobile is larger than |
74 | * removable-by-driver pages reported by notifier, we'll fail. |
75 | */ |
76 | |
77 | out: |
78 | if (!ret) { |
79 | set_pageblock_isolate(page); |
80 | move_freepages_block(zone, page, MIGRATE_ISOLATE); |
81 | } |
82 | |
83 | spin_unlock_irqrestore(&zone->lock, flags); |
84 | if (!ret) |
85 | drain_all_pages(); |
86 | return ret; |
87 | } |
88 | |
89 | void unset_migratetype_isolate(struct page *page, unsigned migratetype) |
90 | { |
91 | struct zone *zone; |
92 | unsigned long flags; |
93 | zone = page_zone(page); |
94 | spin_lock_irqsave(&zone->lock, flags); |
95 | if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE) |
96 | goto out; |
97 | move_freepages_block(zone, page, migratetype); |
98 | restore_pageblock_isolate(page, migratetype); |
99 | out: |
100 | spin_unlock_irqrestore(&zone->lock, flags); |
101 | } |
102 | |
103 | static inline struct page * |
104 | __first_valid_page(unsigned long pfn, unsigned long nr_pages) |
105 | { |
106 | int i; |
107 | for (i = 0; i < nr_pages; i++) |
108 | if (pfn_valid_within(pfn + i)) |
109 | break; |
110 | if (unlikely(i == nr_pages)) |
111 | return NULL; |
112 | return pfn_to_page(pfn + i); |
113 | } |
114 | |
115 | /* |
116 | * start_isolate_page_range() -- make page-allocation-type of range of pages |
117 | * to be MIGRATE_ISOLATE. |
118 | * @start_pfn: The lower PFN of the range to be isolated. |
119 | * @end_pfn: The upper PFN of the range to be isolated. |
120 | * @migratetype: migrate type to set in error recovery. |
121 | * |
122 | * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in |
123 | * the range will never be allocated. Any free pages and pages freed in the |
124 | * future will not be allocated again. |
125 | * |
126 | * start_pfn/end_pfn must be aligned to pageblock_order. |
127 | * Returns 0 on success and -EBUSY if any part of range cannot be isolated. |
128 | */ |
129 | int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, |
130 | unsigned migratetype) |
131 | { |
132 | unsigned long pfn; |
133 | unsigned long undo_pfn; |
134 | struct page *page; |
135 | |
136 | BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); |
137 | BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); |
138 | |
139 | for (pfn = start_pfn; |
140 | pfn < end_pfn; |
141 | pfn += pageblock_nr_pages) { |
142 | page = __first_valid_page(pfn, pageblock_nr_pages); |
143 | if (page && set_migratetype_isolate(page)) { |
144 | undo_pfn = pfn; |
145 | goto undo; |
146 | } |
147 | } |
148 | return 0; |
149 | undo: |
150 | for (pfn = start_pfn; |
151 | pfn < undo_pfn; |
152 | pfn += pageblock_nr_pages) |
153 | unset_migratetype_isolate(pfn_to_page(pfn), migratetype); |
154 | |
155 | return -EBUSY; |
156 | } |
157 | |
158 | /* |
159 | * Make isolated pages available again. |
160 | */ |
161 | int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, |
162 | unsigned migratetype) |
163 | { |
164 | unsigned long pfn; |
165 | struct page *page; |
166 | BUG_ON((start_pfn) & (pageblock_nr_pages - 1)); |
167 | BUG_ON((end_pfn) & (pageblock_nr_pages - 1)); |
168 | for (pfn = start_pfn; |
169 | pfn < end_pfn; |
170 | pfn += pageblock_nr_pages) { |
171 | page = __first_valid_page(pfn, pageblock_nr_pages); |
172 | if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE) |
173 | continue; |
174 | unset_migratetype_isolate(page, migratetype); |
175 | } |
176 | return 0; |
177 | } |
178 | /* |
179 | * Test all pages in the range is free(means isolated) or not. |
180 | * all pages in [start_pfn...end_pfn) must be in the same zone. |
181 | * zone->lock must be held before call this. |
182 | * |
183 | * Returns 1 if all pages in the range are isolated. |
184 | */ |
185 | static int |
186 | __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn) |
187 | { |
188 | struct page *page; |
189 | |
190 | while (pfn < end_pfn) { |
191 | if (!pfn_valid_within(pfn)) { |
192 | pfn++; |
193 | continue; |
194 | } |
195 | page = pfn_to_page(pfn); |
196 | if (PageBuddy(page)) |
197 | pfn += 1 << page_order(page); |
198 | else if (page_count(page) == 0 && |
199 | page_private(page) == MIGRATE_ISOLATE) |
200 | pfn += 1; |
201 | else |
202 | break; |
203 | } |
204 | if (pfn < end_pfn) |
205 | return 0; |
206 | return 1; |
207 | } |
208 | |
209 | int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn) |
210 | { |
211 | unsigned long pfn, flags; |
212 | struct page *page; |
213 | struct zone *zone; |
214 | int ret; |
215 | |
216 | /* |
217 | * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page |
218 | * is not aligned to pageblock_nr_pages. |
219 | * Then we just check pagetype fist. |
220 | */ |
221 | for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { |
222 | page = __first_valid_page(pfn, pageblock_nr_pages); |
223 | if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE) |
224 | break; |
225 | } |
226 | page = __first_valid_page(start_pfn, end_pfn - start_pfn); |
227 | if ((pfn < end_pfn) || !page) |
228 | return -EBUSY; |
229 | /* Check all pages are free or Marked as ISOLATED */ |
230 | zone = page_zone(page); |
231 | spin_lock_irqsave(&zone->lock, flags); |
232 | ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn); |
233 | spin_unlock_irqrestore(&zone->lock, flags); |
234 | return ret ? 0 : -EBUSY; |
235 | } |
236 |
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