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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
18static 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 /*
32 * We assume the caller intended to SET migrate type to isolate.
33 * If it is already set, then someone else must have raced and
34 * set it before us. Return -EBUSY
35 */
36 if (is_migrate_isolate_page(page))
37 goto out;
38
39 pfn = page_to_pfn(page);
40 arg.start_pfn = pfn;
41 arg.nr_pages = pageblock_nr_pages;
42 arg.pages_found = 0;
43
44 /*
45 * It may be possible to isolate a pageblock even if the
46 * migratetype is not MIGRATE_MOVABLE. The memory isolation
47 * notifier chain is used by balloon drivers to return the
48 * number of pages in a range that are held by the balloon
49 * driver to shrink memory. If all the pages are accounted for
50 * by balloons, are free, or on the LRU, isolation can continue.
51 * Later, for example, when memory hotplug notifier runs, these
52 * pages reported as "can be isolated" should be isolated(freed)
53 * by the balloon driver through the memory notifier chain.
54 */
55 notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
56 notifier_ret = notifier_to_errno(notifier_ret);
57 if (notifier_ret)
58 goto out;
59 /*
60 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
61 * We just check MOVABLE pages.
62 */
63 if (!has_unmovable_pages(zone, page, arg.pages_found, migratetype,
64 skip_hwpoisoned_pages))
65 ret = 0;
66
67 /*
68 * immobile means "not-on-lru" pages. If immobile is larger than
69 * removable-by-driver pages reported by notifier, we'll fail.
70 */
71
72out:
73 if (!ret) {
74 unsigned long nr_pages;
75 int mt = get_pageblock_migratetype(page);
76
77 set_pageblock_migratetype(page, MIGRATE_ISOLATE);
78 zone->nr_isolate_pageblock++;
79 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE,
80 NULL);
81
82 __mod_zone_freepage_state(zone, -nr_pages, mt);
83 }
84
85 spin_unlock_irqrestore(&zone->lock, flags);
86 if (!ret)
87 drain_all_pages(zone);
88 return ret;
89}
90
91static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
92{
93 struct zone *zone;
94 unsigned long flags, nr_pages;
95 bool isolated_page = false;
96 unsigned int order;
97 unsigned long pfn, buddy_pfn;
98 struct page *buddy;
99
100 zone = page_zone(page);
101 spin_lock_irqsave(&zone->lock, flags);
102 if (!is_migrate_isolate_page(page))
103 goto out;
104
105 /*
106 * Because freepage with more than pageblock_order on isolated
107 * pageblock is restricted to merge due to freepage counting problem,
108 * it is possible that there is free buddy page.
109 * move_freepages_block() doesn't care of merge so we need other
110 * approach in order to merge them. Isolation and free will make
111 * these pages to be merged.
112 */
113 if (PageBuddy(page)) {
114 order = page_order(page);
115 if (order >= pageblock_order) {
116 pfn = page_to_pfn(page);
117 buddy_pfn = __find_buddy_pfn(pfn, order);
118 buddy = page + (buddy_pfn - pfn);
119
120 if (pfn_valid_within(buddy_pfn) &&
121 !is_migrate_isolate_page(buddy)) {
122 __isolate_free_page(page, order);
123 isolated_page = true;
124 }
125 }
126 }
127
128 /*
129 * If we isolate freepage with more than pageblock_order, there
130 * should be no freepage in the range, so we could avoid costly
131 * pageblock scanning for freepage moving.
132 */
133 if (!isolated_page) {
134 nr_pages = move_freepages_block(zone, page, migratetype, NULL);
135 __mod_zone_freepage_state(zone, nr_pages, migratetype);
136 }
137 set_pageblock_migratetype(page, migratetype);
138 zone->nr_isolate_pageblock--;
139out:
140 spin_unlock_irqrestore(&zone->lock, flags);
141 if (isolated_page) {
142 post_alloc_hook(page, order, __GFP_MOVABLE);
143 __free_pages(page, order);
144 }
145}
146
147static inline struct page *
148__first_valid_page(unsigned long pfn, unsigned long nr_pages)
149{
150 int i;
151
152 for (i = 0; i < nr_pages; i++) {
153 struct page *page;
154
155 if (!pfn_valid_within(pfn + i))
156 continue;
157 page = pfn_to_online_page(pfn + i);
158 if (!page)
159 continue;
160 return page;
161 }
162 return NULL;
163}
164
165/*
166 * start_isolate_page_range() -- make page-allocation-type of range of pages
167 * to be MIGRATE_ISOLATE.
168 * @start_pfn: The lower PFN of the range to be isolated.
169 * @end_pfn: The upper PFN of the range to be isolated.
170 * @migratetype: migrate type to set in error recovery.
171 *
172 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
173 * the range will never be allocated. Any free pages and pages freed in the
174 * future will not be allocated again.
175 *
176 * start_pfn/end_pfn must be aligned to pageblock_order.
177 * Return 0 on success and -EBUSY if any part of range cannot be isolated.
178 *
179 * There is no high level synchronization mechanism that prevents two threads
180 * from trying to isolate overlapping ranges. If this happens, one thread
181 * will notice pageblocks in the overlapping range already set to isolate.
182 * This happens in set_migratetype_isolate, and set_migratetype_isolate
183 * returns an error. We then clean up by restoring the migration type on
184 * pageblocks we may have modified and return -EBUSY to caller. This
185 * prevents two threads from simultaneously working on overlapping ranges.
186 */
187int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
188 unsigned migratetype, bool skip_hwpoisoned_pages)
189{
190 unsigned long pfn;
191 unsigned long undo_pfn;
192 struct page *page;
193
194 BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
195 BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
196
197 for (pfn = start_pfn;
198 pfn < end_pfn;
199 pfn += pageblock_nr_pages) {
200 page = __first_valid_page(pfn, pageblock_nr_pages);
201 if (page &&
202 set_migratetype_isolate(page, migratetype, skip_hwpoisoned_pages)) {
203 undo_pfn = pfn;
204 goto undo;
205 }
206 }
207 return 0;
208undo:
209 for (pfn = start_pfn;
210 pfn < undo_pfn;
211 pfn += pageblock_nr_pages) {
212 struct page *page = pfn_to_online_page(pfn);
213 if (!page)
214 continue;
215 unset_migratetype_isolate(page, migratetype);
216 }
217
218 return -EBUSY;
219}
220
221/*
222 * Make isolated pages available again.
223 */
224int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
225 unsigned migratetype)
226{
227 unsigned long pfn;
228 struct page *page;
229
230 BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
231 BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
232
233 for (pfn = start_pfn;
234 pfn < end_pfn;
235 pfn += pageblock_nr_pages) {
236 page = __first_valid_page(pfn, pageblock_nr_pages);
237 if (!page || !is_migrate_isolate_page(page))
238 continue;
239 unset_migratetype_isolate(page, migratetype);
240 }
241 return 0;
242}
243/*
244 * Test all pages in the range is free(means isolated) or not.
245 * all pages in [start_pfn...end_pfn) must be in the same zone.
246 * zone->lock must be held before call this.
247 *
248 * Returns the last tested pfn.
249 */
250static unsigned long
251__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
252 bool skip_hwpoisoned_pages)
253{
254 struct page *page;
255
256 while (pfn < end_pfn) {
257 if (!pfn_valid_within(pfn)) {
258 pfn++;
259 continue;
260 }
261 page = pfn_to_page(pfn);
262 if (PageBuddy(page))
263 /*
264 * If the page is on a free list, it has to be on
265 * the correct MIGRATE_ISOLATE freelist. There is no
266 * simple way to verify that as VM_BUG_ON(), though.
267 */
268 pfn += 1 << page_order(page);
269 else if (skip_hwpoisoned_pages && PageHWPoison(page))
270 /* A HWPoisoned page cannot be also PageBuddy */
271 pfn++;
272 else
273 break;
274 }
275
276 return pfn;
277}
278
279/* Caller should ensure that requested range is in a single zone */
280int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
281 bool skip_hwpoisoned_pages)
282{
283 unsigned long pfn, flags;
284 struct page *page;
285 struct zone *zone;
286
287 /*
288 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
289 * are not aligned to pageblock_nr_pages.
290 * Then we just check migratetype first.
291 */
292 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
293 page = __first_valid_page(pfn, pageblock_nr_pages);
294 if (page && !is_migrate_isolate_page(page))
295 break;
296 }
297 page = __first_valid_page(start_pfn, end_pfn - start_pfn);
298 if ((pfn < end_pfn) || !page)
299 return -EBUSY;
300 /* Check all pages are free or marked as ISOLATED */
301 zone = page_zone(page);
302 spin_lock_irqsave(&zone->lock, flags);
303 pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
304 skip_hwpoisoned_pages);
305 spin_unlock_irqrestore(&zone->lock, flags);
306
307 trace_test_pages_isolated(start_pfn, end_pfn, pfn);
308
309 return pfn < end_pfn ? -EBUSY : 0;
310}
311
312struct page *alloc_migrate_target(struct page *page, unsigned long private)
313{
314 return new_page_nodemask(page, numa_node_id(), &node_states[N_MEMORY]);
315}
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 "internal.h"
12
13#define CREATE_TRACE_POINTS
14#include <trace/events/page_isolation.h>
15
16static int set_migratetype_isolate(struct page *page,
17 bool skip_hwpoisoned_pages)
18{
19 struct zone *zone;
20 unsigned long flags, pfn;
21 struct memory_isolate_notify arg;
22 int notifier_ret;
23 int ret = -EBUSY;
24
25 zone = page_zone(page);
26
27 spin_lock_irqsave(&zone->lock, flags);
28
29 pfn = page_to_pfn(page);
30 arg.start_pfn = pfn;
31 arg.nr_pages = pageblock_nr_pages;
32 arg.pages_found = 0;
33
34 /*
35 * It may be possible to isolate a pageblock even if the
36 * migratetype is not MIGRATE_MOVABLE. The memory isolation
37 * notifier chain is used by balloon drivers to return the
38 * number of pages in a range that are held by the balloon
39 * driver to shrink memory. If all the pages are accounted for
40 * by balloons, are free, or on the LRU, isolation can continue.
41 * Later, for example, when memory hotplug notifier runs, these
42 * pages reported as "can be isolated" should be isolated(freed)
43 * by the balloon driver through the memory notifier chain.
44 */
45 notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
46 notifier_ret = notifier_to_errno(notifier_ret);
47 if (notifier_ret)
48 goto out;
49 /*
50 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
51 * We just check MOVABLE pages.
52 */
53 if (!has_unmovable_pages(zone, page, arg.pages_found,
54 skip_hwpoisoned_pages))
55 ret = 0;
56
57 /*
58 * immobile means "not-on-lru" pages. If immobile is larger than
59 * removable-by-driver pages reported by notifier, we'll fail.
60 */
61
62out:
63 if (!ret) {
64 unsigned long nr_pages;
65 int migratetype = get_pageblock_migratetype(page);
66
67 set_pageblock_migratetype(page, MIGRATE_ISOLATE);
68 zone->nr_isolate_pageblock++;
69 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
70
71 __mod_zone_freepage_state(zone, -nr_pages, migratetype);
72 }
73
74 spin_unlock_irqrestore(&zone->lock, flags);
75 if (!ret)
76 drain_all_pages(zone);
77 return ret;
78}
79
80static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
81{
82 struct zone *zone;
83 unsigned long flags, nr_pages;
84 bool isolated_page = false;
85 unsigned int order;
86 unsigned long page_idx, buddy_idx;
87 struct page *buddy;
88
89 zone = page_zone(page);
90 spin_lock_irqsave(&zone->lock, flags);
91 if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
92 goto out;
93
94 /*
95 * Because freepage with more than pageblock_order on isolated
96 * pageblock is restricted to merge due to freepage counting problem,
97 * it is possible that there is free buddy page.
98 * move_freepages_block() doesn't care of merge so we need other
99 * approach in order to merge them. Isolation and free will make
100 * these pages to be merged.
101 */
102 if (PageBuddy(page)) {
103 order = page_order(page);
104 if (order >= pageblock_order) {
105 page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
106 buddy_idx = __find_buddy_index(page_idx, order);
107 buddy = page + (buddy_idx - page_idx);
108
109 if (pfn_valid_within(page_to_pfn(buddy)) &&
110 !is_migrate_isolate_page(buddy)) {
111 __isolate_free_page(page, order);
112 isolated_page = true;
113 }
114 }
115 }
116
117 /*
118 * If we isolate freepage with more than pageblock_order, there
119 * should be no freepage in the range, so we could avoid costly
120 * pageblock scanning for freepage moving.
121 */
122 if (!isolated_page) {
123 nr_pages = move_freepages_block(zone, page, migratetype);
124 __mod_zone_freepage_state(zone, nr_pages, migratetype);
125 }
126 set_pageblock_migratetype(page, migratetype);
127 zone->nr_isolate_pageblock--;
128out:
129 spin_unlock_irqrestore(&zone->lock, flags);
130 if (isolated_page) {
131 post_alloc_hook(page, order, __GFP_MOVABLE);
132 __free_pages(page, order);
133 }
134}
135
136static inline struct page *
137__first_valid_page(unsigned long pfn, unsigned long nr_pages)
138{
139 int i;
140 for (i = 0; i < nr_pages; i++)
141 if (pfn_valid_within(pfn + i))
142 break;
143 if (unlikely(i == nr_pages))
144 return NULL;
145 return pfn_to_page(pfn + i);
146}
147
148/*
149 * start_isolate_page_range() -- make page-allocation-type of range of pages
150 * to be MIGRATE_ISOLATE.
151 * @start_pfn: The lower PFN of the range to be isolated.
152 * @end_pfn: The upper PFN of the range to be isolated.
153 * @migratetype: migrate type to set in error recovery.
154 *
155 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
156 * the range will never be allocated. Any free pages and pages freed in the
157 * future will not be allocated again.
158 *
159 * start_pfn/end_pfn must be aligned to pageblock_order.
160 * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
161 */
162int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
163 unsigned migratetype, bool skip_hwpoisoned_pages)
164{
165 unsigned long pfn;
166 unsigned long undo_pfn;
167 struct page *page;
168
169 BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
170 BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
171
172 for (pfn = start_pfn;
173 pfn < end_pfn;
174 pfn += pageblock_nr_pages) {
175 page = __first_valid_page(pfn, pageblock_nr_pages);
176 if (page &&
177 set_migratetype_isolate(page, skip_hwpoisoned_pages)) {
178 undo_pfn = pfn;
179 goto undo;
180 }
181 }
182 return 0;
183undo:
184 for (pfn = start_pfn;
185 pfn < undo_pfn;
186 pfn += pageblock_nr_pages)
187 unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
188
189 return -EBUSY;
190}
191
192/*
193 * Make isolated pages available again.
194 */
195int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
196 unsigned migratetype)
197{
198 unsigned long pfn;
199 struct page *page;
200
201 BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
202 BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
203
204 for (pfn = start_pfn;
205 pfn < end_pfn;
206 pfn += pageblock_nr_pages) {
207 page = __first_valid_page(pfn, pageblock_nr_pages);
208 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
209 continue;
210 unset_migratetype_isolate(page, migratetype);
211 }
212 return 0;
213}
214/*
215 * Test all pages in the range is free(means isolated) or not.
216 * all pages in [start_pfn...end_pfn) must be in the same zone.
217 * zone->lock must be held before call this.
218 *
219 * Returns the last tested pfn.
220 */
221static unsigned long
222__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
223 bool skip_hwpoisoned_pages)
224{
225 struct page *page;
226
227 while (pfn < end_pfn) {
228 if (!pfn_valid_within(pfn)) {
229 pfn++;
230 continue;
231 }
232 page = pfn_to_page(pfn);
233 if (PageBuddy(page))
234 /*
235 * If the page is on a free list, it has to be on
236 * the correct MIGRATE_ISOLATE freelist. There is no
237 * simple way to verify that as VM_BUG_ON(), though.
238 */
239 pfn += 1 << page_order(page);
240 else if (skip_hwpoisoned_pages && PageHWPoison(page))
241 /* A HWPoisoned page cannot be also PageBuddy */
242 pfn++;
243 else
244 break;
245 }
246
247 return pfn;
248}
249
250/* Caller should ensure that requested range is in a single zone */
251int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
252 bool skip_hwpoisoned_pages)
253{
254 unsigned long pfn, flags;
255 struct page *page;
256 struct zone *zone;
257
258 /*
259 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
260 * are not aligned to pageblock_nr_pages.
261 * Then we just check migratetype first.
262 */
263 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
264 page = __first_valid_page(pfn, pageblock_nr_pages);
265 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
266 break;
267 }
268 page = __first_valid_page(start_pfn, end_pfn - start_pfn);
269 if ((pfn < end_pfn) || !page)
270 return -EBUSY;
271 /* Check all pages are free or marked as ISOLATED */
272 zone = page_zone(page);
273 spin_lock_irqsave(&zone->lock, flags);
274 pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
275 skip_hwpoisoned_pages);
276 spin_unlock_irqrestore(&zone->lock, flags);
277
278 trace_test_pages_isolated(start_pfn, end_pfn, pfn);
279
280 return pfn < end_pfn ? -EBUSY : 0;
281}
282
283struct page *alloc_migrate_target(struct page *page, unsigned long private,
284 int **resultp)
285{
286 gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
287
288 /*
289 * TODO: allocate a destination hugepage from a nearest neighbor node,
290 * accordance with memory policy of the user process if possible. For
291 * now as a simple work-around, we use the next node for destination.
292 */
293 if (PageHuge(page))
294 return alloc_huge_page_node(page_hstate(compound_head(page)),
295 next_node_in(page_to_nid(page),
296 node_online_map));
297
298 if (PageHighMem(page))
299 gfp_mask |= __GFP_HIGHMEM;
300
301 return alloc_page(gfp_mask);
302}