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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 <linux/hugetlb.h> | |
10 | #include <linux/page_owner.h> | |
11 | #include <linux/migrate.h> | |
12 | #include "internal.h" | |
13 | ||
14 | #define CREATE_TRACE_POINTS | |
15 | #include <trace/events/page_isolation.h> | |
16 | ||
17 | static int set_migratetype_isolate(struct page *page, | |
18 | bool skip_hwpoisoned_pages) | |
19 | { | |
20 | struct zone *zone; | |
21 | unsigned long flags, pfn; | |
22 | struct memory_isolate_notify arg; | |
23 | int notifier_ret; | |
24 | int ret = -EBUSY; | |
25 | ||
26 | zone = page_zone(page); | |
27 | ||
28 | spin_lock_irqsave(&zone->lock, flags); | |
29 | ||
30 | pfn = page_to_pfn(page); | |
31 | arg.start_pfn = pfn; | |
32 | arg.nr_pages = pageblock_nr_pages; | |
33 | arg.pages_found = 0; | |
34 | ||
35 | /* | |
36 | * It may be possible to isolate a pageblock even if the | |
37 | * migratetype is not MIGRATE_MOVABLE. The memory isolation | |
38 | * notifier chain is used by balloon drivers to return the | |
39 | * number of pages in a range that are held by the balloon | |
40 | * driver to shrink memory. If all the pages are accounted for | |
41 | * by balloons, are free, or on the LRU, isolation can continue. | |
42 | * Later, for example, when memory hotplug notifier runs, these | |
43 | * pages reported as "can be isolated" should be isolated(freed) | |
44 | * by the balloon driver through the memory notifier chain. | |
45 | */ | |
46 | notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg); | |
47 | notifier_ret = notifier_to_errno(notifier_ret); | |
48 | if (notifier_ret) | |
49 | goto out; | |
50 | /* | |
51 | * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. | |
52 | * We just check MOVABLE pages. | |
53 | */ | |
54 | if (!has_unmovable_pages(zone, page, arg.pages_found, | |
55 | skip_hwpoisoned_pages)) | |
56 | ret = 0; | |
57 | ||
58 | /* | |
59 | * immobile means "not-on-lru" pages. If immobile is larger than | |
60 | * removable-by-driver pages reported by notifier, we'll fail. | |
61 | */ | |
62 | ||
63 | out: | |
64 | if (!ret) { | |
65 | unsigned long nr_pages; | |
66 | int migratetype = get_pageblock_migratetype(page); | |
67 | ||
68 | set_pageblock_migratetype(page, MIGRATE_ISOLATE); | |
69 | zone->nr_isolate_pageblock++; | |
70 | nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE, | |
71 | NULL); | |
72 | ||
73 | __mod_zone_freepage_state(zone, -nr_pages, migratetype); | |
74 | } | |
75 | ||
76 | spin_unlock_irqrestore(&zone->lock, flags); | |
77 | if (!ret) | |
78 | drain_all_pages(zone); | |
79 | return ret; | |
80 | } | |
81 | ||
82 | static void unset_migratetype_isolate(struct page *page, unsigned migratetype) | |
83 | { | |
84 | struct zone *zone; | |
85 | unsigned long flags, nr_pages; | |
86 | bool isolated_page = false; | |
87 | unsigned int order; | |
88 | unsigned long pfn, buddy_pfn; | |
89 | struct page *buddy; | |
90 | ||
91 | zone = page_zone(page); | |
92 | spin_lock_irqsave(&zone->lock, flags); | |
93 | if (!is_migrate_isolate_page(page)) | |
94 | goto out; | |
95 | ||
96 | /* | |
97 | * Because freepage with more than pageblock_order on isolated | |
98 | * pageblock is restricted to merge due to freepage counting problem, | |
99 | * it is possible that there is free buddy page. | |
100 | * move_freepages_block() doesn't care of merge so we need other | |
101 | * approach in order to merge them. Isolation and free will make | |
102 | * these pages to be merged. | |
103 | */ | |
104 | if (PageBuddy(page)) { | |
105 | order = page_order(page); | |
106 | if (order >= pageblock_order) { | |
107 | pfn = page_to_pfn(page); | |
108 | buddy_pfn = __find_buddy_pfn(pfn, order); | |
109 | buddy = page + (buddy_pfn - pfn); | |
110 | ||
111 | if (pfn_valid_within(buddy_pfn) && | |
112 | !is_migrate_isolate_page(buddy)) { | |
113 | __isolate_free_page(page, order); | |
114 | isolated_page = true; | |
115 | } | |
116 | } | |
117 | } | |
118 | ||
119 | /* | |
120 | * If we isolate freepage with more than pageblock_order, there | |
121 | * should be no freepage in the range, so we could avoid costly | |
122 | * pageblock scanning for freepage moving. | |
123 | */ | |
124 | if (!isolated_page) { | |
125 | nr_pages = move_freepages_block(zone, page, migratetype, NULL); | |
126 | __mod_zone_freepage_state(zone, nr_pages, migratetype); | |
127 | } | |
128 | set_pageblock_migratetype(page, migratetype); | |
129 | zone->nr_isolate_pageblock--; | |
130 | out: | |
131 | spin_unlock_irqrestore(&zone->lock, flags); | |
132 | if (isolated_page) { | |
133 | post_alloc_hook(page, order, __GFP_MOVABLE); | |
134 | __free_pages(page, order); | |
135 | } | |
136 | } | |
137 | ||
138 | static inline struct page * | |
139 | __first_valid_page(unsigned long pfn, unsigned long nr_pages) | |
140 | { | |
141 | int i; | |
142 | ||
143 | for (i = 0; i < nr_pages; i++) { | |
144 | struct page *page; | |
145 | ||
146 | if (!pfn_valid_within(pfn + i)) | |
147 | continue; | |
148 | page = pfn_to_online_page(pfn + i); | |
149 | if (!page) | |
150 | continue; | |
151 | return page; | |
152 | } | |
153 | return NULL; | |
154 | } | |
155 | ||
156 | /* | |
157 | * start_isolate_page_range() -- make page-allocation-type of range of pages | |
158 | * to be MIGRATE_ISOLATE. | |
159 | * @start_pfn: The lower PFN of the range to be isolated. | |
160 | * @end_pfn: The upper PFN of the range to be isolated. | |
161 | * @migratetype: migrate type to set in error recovery. | |
162 | * | |
163 | * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in | |
164 | * the range will never be allocated. Any free pages and pages freed in the | |
165 | * future will not be allocated again. | |
166 | * | |
167 | * start_pfn/end_pfn must be aligned to pageblock_order. | |
168 | * Returns 0 on success and -EBUSY if any part of range cannot be isolated. | |
169 | */ | |
170 | int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, | |
171 | unsigned migratetype, bool skip_hwpoisoned_pages) | |
172 | { | |
173 | unsigned long pfn; | |
174 | unsigned long undo_pfn; | |
175 | struct page *page; | |
176 | ||
177 | BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); | |
178 | BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); | |
179 | ||
180 | for (pfn = start_pfn; | |
181 | pfn < end_pfn; | |
182 | pfn += pageblock_nr_pages) { | |
183 | page = __first_valid_page(pfn, pageblock_nr_pages); | |
184 | if (page && | |
185 | set_migratetype_isolate(page, skip_hwpoisoned_pages)) { | |
186 | undo_pfn = pfn; | |
187 | goto undo; | |
188 | } | |
189 | } | |
190 | return 0; | |
191 | undo: | |
192 | for (pfn = start_pfn; | |
193 | pfn < undo_pfn; | |
194 | pfn += pageblock_nr_pages) { | |
195 | struct page *page = pfn_to_online_page(pfn); | |
196 | if (!page) | |
197 | continue; | |
198 | unset_migratetype_isolate(page, migratetype); | |
199 | } | |
200 | ||
201 | return -EBUSY; | |
202 | } | |
203 | ||
204 | /* | |
205 | * Make isolated pages available again. | |
206 | */ | |
207 | int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, | |
208 | unsigned migratetype) | |
209 | { | |
210 | unsigned long pfn; | |
211 | struct page *page; | |
212 | ||
213 | BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); | |
214 | BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); | |
215 | ||
216 | for (pfn = start_pfn; | |
217 | pfn < end_pfn; | |
218 | pfn += pageblock_nr_pages) { | |
219 | page = __first_valid_page(pfn, pageblock_nr_pages); | |
220 | if (!page || !is_migrate_isolate_page(page)) | |
221 | continue; | |
222 | unset_migratetype_isolate(page, migratetype); | |
223 | } | |
224 | return 0; | |
225 | } | |
226 | /* | |
227 | * Test all pages in the range is free(means isolated) or not. | |
228 | * all pages in [start_pfn...end_pfn) must be in the same zone. | |
229 | * zone->lock must be held before call this. | |
230 | * | |
231 | * Returns the last tested pfn. | |
232 | */ | |
233 | static unsigned long | |
234 | __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, | |
235 | bool skip_hwpoisoned_pages) | |
236 | { | |
237 | struct page *page; | |
238 | ||
239 | while (pfn < end_pfn) { | |
240 | if (!pfn_valid_within(pfn)) { | |
241 | pfn++; | |
242 | continue; | |
243 | } | |
244 | page = pfn_to_page(pfn); | |
245 | if (PageBuddy(page)) | |
246 | /* | |
247 | * If the page is on a free list, it has to be on | |
248 | * the correct MIGRATE_ISOLATE freelist. There is no | |
249 | * simple way to verify that as VM_BUG_ON(), though. | |
250 | */ | |
251 | pfn += 1 << page_order(page); | |
252 | else if (skip_hwpoisoned_pages && PageHWPoison(page)) | |
253 | /* A HWPoisoned page cannot be also PageBuddy */ | |
254 | pfn++; | |
255 | else | |
256 | break; | |
257 | } | |
258 | ||
259 | return pfn; | |
260 | } | |
261 | ||
262 | /* Caller should ensure that requested range is in a single zone */ | |
263 | int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, | |
264 | bool skip_hwpoisoned_pages) | |
265 | { | |
266 | unsigned long pfn, flags; | |
267 | struct page *page; | |
268 | struct zone *zone; | |
269 | ||
270 | /* | |
271 | * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages | |
272 | * are not aligned to pageblock_nr_pages. | |
273 | * Then we just check migratetype first. | |
274 | */ | |
275 | for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { | |
276 | page = __first_valid_page(pfn, pageblock_nr_pages); | |
277 | if (page && !is_migrate_isolate_page(page)) | |
278 | break; | |
279 | } | |
280 | page = __first_valid_page(start_pfn, end_pfn - start_pfn); | |
281 | if ((pfn < end_pfn) || !page) | |
282 | return -EBUSY; | |
283 | /* Check all pages are free or marked as ISOLATED */ | |
284 | zone = page_zone(page); | |
285 | spin_lock_irqsave(&zone->lock, flags); | |
286 | pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, | |
287 | skip_hwpoisoned_pages); | |
288 | spin_unlock_irqrestore(&zone->lock, flags); | |
289 | ||
290 | trace_test_pages_isolated(start_pfn, end_pfn, pfn); | |
291 | ||
292 | return pfn < end_pfn ? -EBUSY : 0; | |
293 | } | |
294 | ||
295 | struct page *alloc_migrate_target(struct page *page, unsigned long private, | |
296 | int **resultp) | |
297 | { | |
298 | return new_page_nodemask(page, numa_node_id(), &node_states[N_MEMORY]); | |
299 | } |