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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 "internal.h"
11
12int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages)
13{
14 struct zone *zone;
15 unsigned long flags, pfn;
16 struct memory_isolate_notify arg;
17 int notifier_ret;
18 int ret = -EBUSY;
19
20 zone = page_zone(page);
21
22 spin_lock_irqsave(&zone->lock, flags);
23
24 pfn = page_to_pfn(page);
25 arg.start_pfn = pfn;
26 arg.nr_pages = pageblock_nr_pages;
27 arg.pages_found = 0;
28
29 /*
30 * It may be possible to isolate a pageblock even if the
31 * migratetype is not MIGRATE_MOVABLE. The memory isolation
32 * notifier chain is used by balloon drivers to return the
33 * number of pages in a range that are held by the balloon
34 * driver to shrink memory. If all the pages are accounted for
35 * by balloons, are free, or on the LRU, isolation can continue.
36 * Later, for example, when memory hotplug notifier runs, these
37 * pages reported as "can be isolated" should be isolated(freed)
38 * by the balloon driver through the memory notifier chain.
39 */
40 notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
41 notifier_ret = notifier_to_errno(notifier_ret);
42 if (notifier_ret)
43 goto out;
44 /*
45 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
46 * We just check MOVABLE pages.
47 */
48 if (!has_unmovable_pages(zone, page, arg.pages_found,
49 skip_hwpoisoned_pages))
50 ret = 0;
51
52 /*
53 * immobile means "not-on-lru" paes. If immobile is larger than
54 * removable-by-driver pages reported by notifier, we'll fail.
55 */
56
57out:
58 if (!ret) {
59 unsigned long nr_pages;
60 int migratetype = get_pageblock_migratetype(page);
61
62 set_pageblock_migratetype(page, MIGRATE_ISOLATE);
63 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
64
65 __mod_zone_freepage_state(zone, -nr_pages, migratetype);
66 }
67
68 spin_unlock_irqrestore(&zone->lock, flags);
69 if (!ret)
70 drain_all_pages();
71 return ret;
72}
73
74void unset_migratetype_isolate(struct page *page, unsigned migratetype)
75{
76 struct zone *zone;
77 unsigned long flags, nr_pages;
78
79 zone = page_zone(page);
80 spin_lock_irqsave(&zone->lock, flags);
81 if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
82 goto out;
83 nr_pages = move_freepages_block(zone, page, migratetype);
84 __mod_zone_freepage_state(zone, nr_pages, migratetype);
85 set_pageblock_migratetype(page, migratetype);
86out:
87 spin_unlock_irqrestore(&zone->lock, flags);
88}
89
90static inline struct page *
91__first_valid_page(unsigned long pfn, unsigned long nr_pages)
92{
93 int i;
94 for (i = 0; i < nr_pages; i++)
95 if (pfn_valid_within(pfn + i))
96 break;
97 if (unlikely(i == nr_pages))
98 return NULL;
99 return pfn_to_page(pfn + i);
100}
101
102/*
103 * start_isolate_page_range() -- make page-allocation-type of range of pages
104 * to be MIGRATE_ISOLATE.
105 * @start_pfn: The lower PFN of the range to be isolated.
106 * @end_pfn: The upper PFN of the range to be isolated.
107 * @migratetype: migrate type to set in error recovery.
108 *
109 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
110 * the range will never be allocated. Any free pages and pages freed in the
111 * future will not be allocated again.
112 *
113 * start_pfn/end_pfn must be aligned to pageblock_order.
114 * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
115 */
116int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
117 unsigned migratetype, bool skip_hwpoisoned_pages)
118{
119 unsigned long pfn;
120 unsigned long undo_pfn;
121 struct page *page;
122
123 BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
124 BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
125
126 for (pfn = start_pfn;
127 pfn < end_pfn;
128 pfn += pageblock_nr_pages) {
129 page = __first_valid_page(pfn, pageblock_nr_pages);
130 if (page &&
131 set_migratetype_isolate(page, skip_hwpoisoned_pages)) {
132 undo_pfn = pfn;
133 goto undo;
134 }
135 }
136 return 0;
137undo:
138 for (pfn = start_pfn;
139 pfn < undo_pfn;
140 pfn += pageblock_nr_pages)
141 unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
142
143 return -EBUSY;
144}
145
146/*
147 * Make isolated pages available again.
148 */
149int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
150 unsigned migratetype)
151{
152 unsigned long pfn;
153 struct page *page;
154 BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
155 BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
156 for (pfn = start_pfn;
157 pfn < end_pfn;
158 pfn += pageblock_nr_pages) {
159 page = __first_valid_page(pfn, pageblock_nr_pages);
160 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
161 continue;
162 unset_migratetype_isolate(page, migratetype);
163 }
164 return 0;
165}
166/*
167 * Test all pages in the range is free(means isolated) or not.
168 * all pages in [start_pfn...end_pfn) must be in the same zone.
169 * zone->lock must be held before call this.
170 *
171 * Returns 1 if all pages in the range are isolated.
172 */
173static int
174__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
175 bool skip_hwpoisoned_pages)
176{
177 struct page *page;
178
179 while (pfn < end_pfn) {
180 if (!pfn_valid_within(pfn)) {
181 pfn++;
182 continue;
183 }
184 page = pfn_to_page(pfn);
185 if (PageBuddy(page)) {
186 /*
187 * If race between isolatation and allocation happens,
188 * some free pages could be in MIGRATE_MOVABLE list
189 * although pageblock's migratation type of the page
190 * is MIGRATE_ISOLATE. Catch it and move the page into
191 * MIGRATE_ISOLATE list.
192 */
193 if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) {
194 struct page *end_page;
195
196 end_page = page + (1 << page_order(page)) - 1;
197 move_freepages(page_zone(page), page, end_page,
198 MIGRATE_ISOLATE);
199 }
200 pfn += 1 << page_order(page);
201 }
202 else if (page_count(page) == 0 &&
203 get_freepage_migratetype(page) == MIGRATE_ISOLATE)
204 pfn += 1;
205 else if (skip_hwpoisoned_pages && PageHWPoison(page)) {
206 /*
207 * The HWPoisoned page may be not in buddy
208 * system, and page_count() is not 0.
209 */
210 pfn++;
211 continue;
212 }
213 else
214 break;
215 }
216 if (pfn < end_pfn)
217 return 0;
218 return 1;
219}
220
221int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
222 bool skip_hwpoisoned_pages)
223{
224 unsigned long pfn, flags;
225 struct page *page;
226 struct zone *zone;
227 int ret;
228
229 /*
230 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
231 * are not aligned to pageblock_nr_pages.
232 * Then we just check migratetype first.
233 */
234 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
235 page = __first_valid_page(pfn, pageblock_nr_pages);
236 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
237 break;
238 }
239 page = __first_valid_page(start_pfn, end_pfn - start_pfn);
240 if ((pfn < end_pfn) || !page)
241 return -EBUSY;
242 /* Check all pages are free or marked as ISOLATED */
243 zone = page_zone(page);
244 spin_lock_irqsave(&zone->lock, flags);
245 ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
246 skip_hwpoisoned_pages);
247 spin_unlock_irqrestore(&zone->lock, flags);
248 return ret ? 0 : -EBUSY;
249}
250
251struct page *alloc_migrate_target(struct page *page, unsigned long private,
252 int **resultp)
253{
254 gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
255
256 /*
257 * TODO: allocate a destination hugepage from a nearest neighbor node,
258 * accordance with memory policy of the user process if possible. For
259 * now as a simple work-around, we use the next node for destination.
260 */
261 if (PageHuge(page)) {
262 nodemask_t src = nodemask_of_node(page_to_nid(page));
263 nodemask_t dst;
264 nodes_complement(dst, src);
265 return alloc_huge_page_node(page_hstate(compound_head(page)),
266 next_node(page_to_nid(page), dst));
267 }
268
269 if (PageHighMem(page))
270 gfp_mask |= __GFP_HIGHMEM;
271
272 return alloc_page(gfp_mask);
273}
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}