]>
Commit | Line | Data |
---|---|---|
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, int isol_flags) | |
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 | /* | |
31 | * We assume the caller intended to SET migrate type to isolate. | |
32 | * If it is already set, then someone else must have raced and | |
33 | * set it before us. Return -EBUSY | |
34 | */ | |
35 | if (is_migrate_isolate_page(page)) | |
36 | goto out; | |
37 | ||
38 | pfn = page_to_pfn(page); | |
39 | arg.start_pfn = pfn; | |
40 | arg.nr_pages = pageblock_nr_pages; | |
41 | arg.pages_found = 0; | |
42 | ||
43 | /* | |
44 | * It may be possible to isolate a pageblock even if the | |
45 | * migratetype is not MIGRATE_MOVABLE. The memory isolation | |
46 | * notifier chain is used by balloon drivers to return the | |
47 | * number of pages in a range that are held by the balloon | |
48 | * driver to shrink memory. If all the pages are accounted for | |
49 | * by balloons, are free, or on the LRU, isolation can continue. | |
50 | * Later, for example, when memory hotplug notifier runs, these | |
51 | * pages reported as "can be isolated" should be isolated(freed) | |
52 | * by the balloon driver through the memory notifier chain. | |
53 | */ | |
54 | notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg); | |
55 | notifier_ret = notifier_to_errno(notifier_ret); | |
56 | if (notifier_ret) | |
57 | goto out; | |
58 | /* | |
59 | * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself. | |
60 | * We just check MOVABLE pages. | |
61 | */ | |
62 | if (!has_unmovable_pages(zone, page, arg.pages_found, migratetype, | |
63 | isol_flags)) | |
64 | ret = 0; | |
65 | ||
66 | /* | |
67 | * immobile means "not-on-lru" pages. If immobile is larger than | |
68 | * removable-by-driver pages reported by notifier, we'll fail. | |
69 | */ | |
70 | ||
71 | out: | |
72 | if (!ret) { | |
73 | unsigned long nr_pages; | |
74 | int mt = get_pageblock_migratetype(page); | |
75 | ||
76 | set_pageblock_migratetype(page, MIGRATE_ISOLATE); | |
77 | zone->nr_isolate_pageblock++; | |
78 | nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE, | |
79 | NULL); | |
80 | ||
81 | __mod_zone_freepage_state(zone, -nr_pages, mt); | |
82 | } | |
83 | ||
84 | spin_unlock_irqrestore(&zone->lock, flags); | |
85 | if (!ret) | |
86 | drain_all_pages(zone); | |
87 | return ret; | |
88 | } | |
89 | ||
90 | static void unset_migratetype_isolate(struct page *page, unsigned migratetype) | |
91 | { | |
92 | struct zone *zone; | |
93 | unsigned long flags, nr_pages; | |
94 | bool isolated_page = false; | |
95 | unsigned int order; | |
96 | unsigned long pfn, buddy_pfn; | |
97 | struct page *buddy; | |
98 | ||
99 | zone = page_zone(page); | |
100 | spin_lock_irqsave(&zone->lock, flags); | |
101 | if (!is_migrate_isolate_page(page)) | |
102 | goto out; | |
103 | ||
104 | /* | |
105 | * Because freepage with more than pageblock_order on isolated | |
106 | * pageblock is restricted to merge due to freepage counting problem, | |
107 | * it is possible that there is free buddy page. | |
108 | * move_freepages_block() doesn't care of merge so we need other | |
109 | * approach in order to merge them. Isolation and free will make | |
110 | * these pages to be merged. | |
111 | */ | |
112 | if (PageBuddy(page)) { | |
113 | order = page_order(page); | |
114 | if (order >= pageblock_order) { | |
115 | pfn = page_to_pfn(page); | |
116 | buddy_pfn = __find_buddy_pfn(pfn, order); | |
117 | buddy = page + (buddy_pfn - pfn); | |
118 | ||
119 | if (pfn_valid_within(buddy_pfn) && | |
120 | !is_migrate_isolate_page(buddy)) { | |
121 | __isolate_free_page(page, order); | |
122 | isolated_page = true; | |
123 | } | |
124 | } | |
125 | } | |
126 | ||
127 | /* | |
128 | * If we isolate freepage with more than pageblock_order, there | |
129 | * should be no freepage in the range, so we could avoid costly | |
130 | * pageblock scanning for freepage moving. | |
131 | */ | |
132 | if (!isolated_page) { | |
133 | nr_pages = move_freepages_block(zone, page, migratetype, NULL); | |
134 | __mod_zone_freepage_state(zone, nr_pages, migratetype); | |
135 | } | |
136 | set_pageblock_migratetype(page, migratetype); | |
137 | zone->nr_isolate_pageblock--; | |
138 | out: | |
139 | spin_unlock_irqrestore(&zone->lock, flags); | |
140 | if (isolated_page) { | |
141 | post_alloc_hook(page, order, __GFP_MOVABLE); | |
142 | __free_pages(page, order); | |
143 | } | |
144 | } | |
145 | ||
146 | static inline struct page * | |
147 | __first_valid_page(unsigned long pfn, unsigned long nr_pages) | |
148 | { | |
149 | int i; | |
150 | ||
151 | for (i = 0; i < nr_pages; i++) { | |
152 | struct page *page; | |
153 | ||
154 | if (!pfn_valid_within(pfn + i)) | |
155 | continue; | |
156 | page = pfn_to_online_page(pfn + i); | |
157 | if (!page) | |
158 | continue; | |
159 | return page; | |
160 | } | |
161 | return NULL; | |
162 | } | |
163 | ||
164 | /** | |
165 | * start_isolate_page_range() - make page-allocation-type of range of pages to | |
166 | * be MIGRATE_ISOLATE. | |
167 | * @start_pfn: The lower PFN of the range to be isolated. | |
168 | * @end_pfn: The upper PFN of the range to be isolated. | |
169 | * start_pfn/end_pfn must be aligned to pageblock_order. | |
170 | * @migratetype: Migrate type to set in error recovery. | |
171 | * @flags: The following flags are allowed (they can be combined in | |
172 | * a bit mask) | |
173 | * SKIP_HWPOISON - ignore hwpoison pages | |
174 | * REPORT_FAILURE - report details about the failure to | |
175 | * isolate the range | |
176 | * | |
177 | * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in | |
178 | * the range will never be allocated. Any free pages and pages freed in the | |
179 | * future will not be allocated again. If specified range includes migrate types | |
180 | * other than MOVABLE or CMA, this will fail with -EBUSY. For isolating all | |
181 | * pages in the range finally, the caller have to free all pages in the range. | |
182 | * test_page_isolated() can be used for test it. | |
183 | * | |
184 | * There is no high level synchronization mechanism that prevents two threads | |
185 | * from trying to isolate overlapping ranges. If this happens, one thread | |
186 | * will notice pageblocks in the overlapping range already set to isolate. | |
187 | * This happens in set_migratetype_isolate, and set_migratetype_isolate | |
188 | * returns an error. We then clean up by restoring the migration type on | |
189 | * pageblocks we may have modified and return -EBUSY to caller. This | |
190 | * prevents two threads from simultaneously working on overlapping ranges. | |
191 | * | |
192 | * Return: the number of isolated pageblocks on success and -EBUSY if any part | |
193 | * of range cannot be isolated. | |
194 | */ | |
195 | int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, | |
196 | unsigned migratetype, int flags) | |
197 | { | |
198 | unsigned long pfn; | |
199 | unsigned long undo_pfn; | |
200 | struct page *page; | |
201 | int nr_isolate_pageblock = 0; | |
202 | ||
203 | BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); | |
204 | BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); | |
205 | ||
206 | for (pfn = start_pfn; | |
207 | pfn < end_pfn; | |
208 | pfn += pageblock_nr_pages) { | |
209 | page = __first_valid_page(pfn, pageblock_nr_pages); | |
210 | if (page) { | |
211 | if (set_migratetype_isolate(page, migratetype, flags)) { | |
212 | undo_pfn = pfn; | |
213 | goto undo; | |
214 | } | |
215 | nr_isolate_pageblock++; | |
216 | } | |
217 | } | |
218 | return nr_isolate_pageblock; | |
219 | undo: | |
220 | for (pfn = start_pfn; | |
221 | pfn < undo_pfn; | |
222 | pfn += pageblock_nr_pages) { | |
223 | struct page *page = pfn_to_online_page(pfn); | |
224 | if (!page) | |
225 | continue; | |
226 | unset_migratetype_isolate(page, migratetype); | |
227 | } | |
228 | ||
229 | return -EBUSY; | |
230 | } | |
231 | ||
232 | /* | |
233 | * Make isolated pages available again. | |
234 | */ | |
235 | int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, | |
236 | unsigned migratetype) | |
237 | { | |
238 | unsigned long pfn; | |
239 | struct page *page; | |
240 | ||
241 | BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); | |
242 | BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages)); | |
243 | ||
244 | for (pfn = start_pfn; | |
245 | pfn < end_pfn; | |
246 | pfn += pageblock_nr_pages) { | |
247 | page = __first_valid_page(pfn, pageblock_nr_pages); | |
248 | if (!page || !is_migrate_isolate_page(page)) | |
249 | continue; | |
250 | unset_migratetype_isolate(page, migratetype); | |
251 | } | |
252 | return 0; | |
253 | } | |
254 | /* | |
255 | * Test all pages in the range is free(means isolated) or not. | |
256 | * all pages in [start_pfn...end_pfn) must be in the same zone. | |
257 | * zone->lock must be held before call this. | |
258 | * | |
259 | * Returns the last tested pfn. | |
260 | */ | |
261 | static unsigned long | |
262 | __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn, | |
263 | bool skip_hwpoisoned_pages) | |
264 | { | |
265 | struct page *page; | |
266 | ||
267 | while (pfn < end_pfn) { | |
268 | if (!pfn_valid_within(pfn)) { | |
269 | pfn++; | |
270 | continue; | |
271 | } | |
272 | page = pfn_to_page(pfn); | |
273 | if (PageBuddy(page)) | |
274 | /* | |
275 | * If the page is on a free list, it has to be on | |
276 | * the correct MIGRATE_ISOLATE freelist. There is no | |
277 | * simple way to verify that as VM_BUG_ON(), though. | |
278 | */ | |
279 | pfn += 1 << page_order(page); | |
280 | else if (skip_hwpoisoned_pages && PageHWPoison(page)) | |
281 | /* A HWPoisoned page cannot be also PageBuddy */ | |
282 | pfn++; | |
283 | else | |
284 | break; | |
285 | } | |
286 | ||
287 | return pfn; | |
288 | } | |
289 | ||
290 | /* Caller should ensure that requested range is in a single zone */ | |
291 | int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn, | |
292 | bool skip_hwpoisoned_pages) | |
293 | { | |
294 | unsigned long pfn, flags; | |
295 | struct page *page; | |
296 | struct zone *zone; | |
297 | ||
298 | /* | |
299 | * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages | |
300 | * are not aligned to pageblock_nr_pages. | |
301 | * Then we just check migratetype first. | |
302 | */ | |
303 | for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { | |
304 | page = __first_valid_page(pfn, pageblock_nr_pages); | |
305 | if (page && !is_migrate_isolate_page(page)) | |
306 | break; | |
307 | } | |
308 | page = __first_valid_page(start_pfn, end_pfn - start_pfn); | |
309 | if ((pfn < end_pfn) || !page) | |
310 | return -EBUSY; | |
311 | /* Check all pages are free or marked as ISOLATED */ | |
312 | zone = page_zone(page); | |
313 | spin_lock_irqsave(&zone->lock, flags); | |
314 | pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, | |
315 | skip_hwpoisoned_pages); | |
316 | spin_unlock_irqrestore(&zone->lock, flags); | |
317 | ||
318 | trace_test_pages_isolated(start_pfn, end_pfn, pfn); | |
319 | ||
320 | return pfn < end_pfn ? -EBUSY : 0; | |
321 | } | |
322 | ||
323 | struct page *alloc_migrate_target(struct page *page, unsigned long private) | |
324 | { | |
325 | return new_page_nodemask(page, numa_node_id(), &node_states[N_MEMORY]); | |
326 | } |