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1 | // SPDX-License-Identifier: GPL-2.0 | |
2 | /* | |
3 | * linux/mm/page_isolation.c | |
4 | */ | |
5 | ||
6 | #include <linux/mm.h> | |
7 | #include <linux/page-isolation.h> | |
8 | #include <linux/pageblock-flags.h> | |
9 | #include <linux/memory.h> | |
10 | #include <linux/hugetlb.h> | |
11 | #include <linux/page_owner.h> | |
12 | #include <linux/migrate.h> | |
13 | #include "internal.h" | |
14 | ||
15 | #define CREATE_TRACE_POINTS | |
16 | #include <trace/events/page_isolation.h> | |
17 | ||
18 | static int set_migratetype_isolate(struct page *page, int migratetype, | |
19 | bool skip_hwpoisoned_pages) | |
20 | { | |
21 | struct zone *zone; | |
22 | unsigned long flags, pfn; | |
23 | struct memory_isolate_notify arg; | |
24 | int notifier_ret; | |
25 | int ret = -EBUSY; | |
26 | ||
27 | zone = page_zone(page); | |
28 | ||
29 | spin_lock_irqsave(&zone->lock, flags); | |
30 | ||
31 | pfn = page_to_pfn(page); | |
32 | arg.start_pfn = pfn; | |
33 | arg.nr_pages = pageblock_nr_pages; | |
34 | arg.pages_found = 0; | |
35 | ||
36 | /* | |
37 | * It may be possible to isolate a pageblock even if the | |
38 | * migratetype is not MIGRATE_MOVABLE. The memory isolation | |
39 | * notifier chain is used by balloon drivers to return the | |
40 | * number of pages in a range that are held by the balloon | |
41 | * driver to shrink memory. If all the pages are accounted for | |
42 | * by balloons, are free, or on the LRU, isolation can continue. | |
43 | * Later, for example, when memory hotplug notifier runs, these | |
44 | * pages reported as "can be isolated" should be isolated(freed) | |
45 | * by the balloon driver through the memory notifier chain. | |
46 | */ | |
47 | notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg); | |
48 | notifier_ret = notifier_to_errno(notifier_ret); | |
49 | if (notifier_ret) | |
50 | goto out; | |
51 | /* | |
52 | * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. | |
53 | * We just check MOVABLE pages. | |
54 | */ | |
55 | if (!has_unmovable_pages(zone, page, arg.pages_found, migratetype, | |
56 | skip_hwpoisoned_pages)) | |
57 | ret = 0; | |
58 | ||
59 | /* | |
60 | * immobile means "not-on-lru" pages. If immobile is larger than | |
61 | * removable-by-driver pages reported by notifier, we'll fail. | |
62 | */ | |
63 | ||
64 | out: | |
65 | if (!ret) { | |
66 | unsigned long nr_pages; | |
67 | int mt = get_pageblock_migratetype(page); | |
68 | ||
69 | set_pageblock_migratetype(page, MIGRATE_ISOLATE); | |
70 | zone->nr_isolate_pageblock++; | |
71 | nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE, | |
72 | NULL); | |
73 | ||
74 | __mod_zone_freepage_state(zone, -nr_pages, mt); | |
75 | } | |
76 | ||
77 | spin_unlock_irqrestore(&zone->lock, flags); | |
78 | if (!ret) | |
79 | drain_all_pages(zone); | |
80 | return ret; | |
81 | } | |
82 | ||
83 | static void unset_migratetype_isolate(struct page *page, unsigned migratetype) | |
84 | { | |
85 | struct zone *zone; | |
86 | unsigned long flags, nr_pages; | |
87 | bool isolated_page = false; | |
88 | unsigned int order; | |
89 | unsigned long pfn, buddy_pfn; | |
90 | struct page *buddy; | |
91 | ||
92 | zone = page_zone(page); | |
93 | spin_lock_irqsave(&zone->lock, flags); | |
94 | if (!is_migrate_isolate_page(page)) | |
95 | goto out; | |
96 | ||
97 | /* | |
98 | * Because freepage with more than pageblock_order on isolated | |
99 | * pageblock is restricted to merge due to freepage counting problem, | |
100 | * it is possible that there is free buddy page. | |
101 | * move_freepages_block() doesn't care of merge so we need other | |
102 | * approach in order to merge them. Isolation and free will make | |
103 | * these pages to be merged. | |
104 | */ | |
105 | if (PageBuddy(page)) { | |
106 | order = page_order(page); | |
107 | if (order >= pageblock_order) { | |
108 | pfn = page_to_pfn(page); | |
109 | buddy_pfn = __find_buddy_pfn(pfn, order); | |
110 | buddy = page + (buddy_pfn - pfn); | |
111 | ||
112 | if (pfn_valid_within(buddy_pfn) && | |
113 | !is_migrate_isolate_page(buddy)) { | |
114 | __isolate_free_page(page, order); | |
115 | isolated_page = true; | |
116 | } | |
117 | } | |
118 | } | |
119 | ||
120 | /* | |
121 | * If we isolate freepage with more than pageblock_order, there | |
122 | * should be no freepage in the range, so we could avoid costly | |
123 | * pageblock scanning for freepage moving. | |
124 | */ | |
125 | if (!isolated_page) { | |
126 | nr_pages = move_freepages_block(zone, page, migratetype, NULL); | |
127 | __mod_zone_freepage_state(zone, nr_pages, migratetype); | |
128 | } | |
129 | set_pageblock_migratetype(page, migratetype); | |
130 | zone->nr_isolate_pageblock--; | |
131 | out: | |
132 | spin_unlock_irqrestore(&zone->lock, flags); | |
133 | if (isolated_page) { | |
134 | post_alloc_hook(page, order, __GFP_MOVABLE); | |
135 | __free_pages(page, order); | |
136 | } | |
137 | } | |
138 | ||
139 | static inline struct page * | |
140 | __first_valid_page(unsigned long pfn, unsigned long nr_pages) | |
141 | { | |
142 | int i; | |
143 | ||
144 | for (i = 0; i < nr_pages; i++) { | |
145 | struct page *page; | |
146 | ||
147 | if (!pfn_valid_within(pfn + i)) | |
148 | continue; | |
149 | page = pfn_to_online_page(pfn + i); | |
150 | if (!page) | |
151 | continue; | |
152 | return page; | |
153 | } | |
154 | return NULL; | |
155 | } | |
156 | ||
157 | /* | |
158 | * start_isolate_page_range() -- make page-allocation-type of range of pages | |
159 | * to be MIGRATE_ISOLATE. | |
160 | * @start_pfn: The lower PFN of the range to be isolated. | |
161 | * @end_pfn: The upper PFN of the range to be isolated. | |
162 | * @migratetype: migrate type to set in error recovery. | |
163 | * | |
164 | * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in | |
165 | * the range will never be allocated. Any free pages and pages freed in the | |
166 | * future will not be allocated again. | |
167 | * | |
168 | * start_pfn/end_pfn must be aligned to pageblock_order. | |
169 | * Returns 0 on success and -EBUSY if any part of range cannot be isolated. | |
170 | */ | |
171 | int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, | |
172 | unsigned migratetype, bool skip_hwpoisoned_pages) | |
173 | { | |
174 | unsigned long pfn; | |
175 | unsigned long undo_pfn; | |
176 | struct page *page; | |
177 | ||
178 | BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); | |
179 | BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); | |
180 | ||
181 | for (pfn = start_pfn; | |
182 | pfn < end_pfn; | |
183 | pfn += pageblock_nr_pages) { | |
184 | page = __first_valid_page(pfn, pageblock_nr_pages); | |
185 | if (page && | |
186 | set_migratetype_isolate(page, migratetype, skip_hwpoisoned_pages)) { | |
187 | undo_pfn = pfn; | |
188 | goto undo; | |
189 | } | |
190 | } | |
191 | return 0; | |
192 | undo: | |
193 | for (pfn = start_pfn; | |
194 | pfn < undo_pfn; | |
195 | pfn += pageblock_nr_pages) { | |
196 | struct page *page = pfn_to_online_page(pfn); | |
197 | if (!page) | |
198 | continue; | |
199 | unset_migratetype_isolate(page, migratetype); | |
200 | } | |
201 | ||
202 | return -EBUSY; | |
203 | } | |
204 | ||
205 | /* | |
206 | * Make isolated pages available again. | |
207 | */ | |
208 | int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, | |
209 | unsigned migratetype) | |
210 | { | |
211 | unsigned long pfn; | |
212 | struct page *page; | |
213 | ||
214 | BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); | |
215 | BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); | |
216 | ||
217 | for (pfn = start_pfn; | |
218 | pfn < end_pfn; | |
219 | pfn += pageblock_nr_pages) { | |
220 | page = __first_valid_page(pfn, pageblock_nr_pages); | |
221 | if (!page || !is_migrate_isolate_page(page)) | |
222 | continue; | |
223 | unset_migratetype_isolate(page, migratetype); | |
224 | } | |
225 | return 0; | |
226 | } | |
227 | /* | |
228 | * Test all pages in the range is free(means isolated) or not. | |
229 | * all pages in [start_pfn...end_pfn) must be in the same zone. | |
230 | * zone->lock must be held before call this. | |
231 | * | |
232 | * Returns the last tested pfn. | |
233 | */ | |
234 | static unsigned long | |
235 | __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, | |
236 | bool skip_hwpoisoned_pages) | |
237 | { | |
238 | struct page *page; | |
239 | ||
240 | while (pfn < end_pfn) { | |
241 | if (!pfn_valid_within(pfn)) { | |
242 | pfn++; | |
243 | continue; | |
244 | } | |
245 | page = pfn_to_page(pfn); | |
246 | if (PageBuddy(page)) | |
247 | /* | |
248 | * If the page is on a free list, it has to be on | |
249 | * the correct MIGRATE_ISOLATE freelist. There is no | |
250 | * simple way to verify that as VM_BUG_ON(), though. | |
251 | */ | |
252 | pfn += 1 << page_order(page); | |
253 | else if (skip_hwpoisoned_pages && PageHWPoison(page)) | |
254 | /* A HWPoisoned page cannot be also PageBuddy */ | |
255 | pfn++; | |
256 | else | |
257 | break; | |
258 | } | |
259 | ||
260 | return pfn; | |
261 | } | |
262 | ||
263 | /* Caller should ensure that requested range is in a single zone */ | |
264 | int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, | |
265 | bool skip_hwpoisoned_pages) | |
266 | { | |
267 | unsigned long pfn, flags; | |
268 | struct page *page; | |
269 | struct zone *zone; | |
270 | ||
271 | /* | |
272 | * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages | |
273 | * are not aligned to pageblock_nr_pages. | |
274 | * Then we just check migratetype first. | |
275 | */ | |
276 | for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { | |
277 | page = __first_valid_page(pfn, pageblock_nr_pages); | |
278 | if (page && !is_migrate_isolate_page(page)) | |
279 | break; | |
280 | } | |
281 | page = __first_valid_page(start_pfn, end_pfn - start_pfn); | |
282 | if ((pfn < end_pfn) || !page) | |
283 | return -EBUSY; | |
284 | /* Check all pages are free or marked as ISOLATED */ | |
285 | zone = page_zone(page); | |
286 | spin_lock_irqsave(&zone->lock, flags); | |
287 | pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, | |
288 | skip_hwpoisoned_pages); | |
289 | spin_unlock_irqrestore(&zone->lock, flags); | |
290 | ||
291 | trace_test_pages_isolated(start_pfn, end_pfn, pfn); | |
292 | ||
293 | return pfn < end_pfn ? -EBUSY : 0; | |
294 | } | |
295 | ||
296 | struct page *alloc_migrate_target(struct page *page, unsigned long private, | |
297 | int **resultp) | |
298 | { | |
299 | return new_page_nodemask(page, numa_node_id(), &node_states[N_MEMORY]); | |
300 | } |