Branch data Line data Source code
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 : 4140 : 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 : 4140 : 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 [ + - ]: 4140 : 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 [ + - ]: 4140 : 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 [ + - ]: 4140 : if (!ret) {
73 : : unsigned long nr_pages;
74 : 4140 : int mt = get_pageblock_migratetype(page);
75 : :
76 : 4140 : set_pageblock_migratetype(page, MIGRATE_ISOLATE);
77 : 4140 : zone->nr_isolate_pageblock++;
78 : 4140 : nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE,
79 : : NULL);
80 : :
81 : 4140 : __mod_zone_freepage_state(zone, -nr_pages, mt);
82 : : }
83 : :
84 : : spin_unlock_irqrestore(&zone->lock, flags);
85 [ + - ]: 4140 : if (!ret)
86 : 4140 : drain_all_pages(zone);
87 : 4140 : return ret;
88 : : }
89 : :
90 : 4140 : 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 : 4140 : spin_lock_irqsave(&zone->lock, flags);
101 [ + - ]: 4140 : 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 [ - + ]: 4140 : if (PageBuddy(page)) {
113 : : order = page_order(page);
114 [ # # ]: 0 : if (order >= pageblock_order) {
115 : 0 : pfn = page_to_pfn(page);
116 : : buddy_pfn = __find_buddy_pfn(pfn, order);
117 : 0 : buddy = page + (buddy_pfn - pfn);
118 : :
119 [ # # ]: 0 : if (pfn_valid_within(buddy_pfn) &&
120 : 0 : !is_migrate_isolate_page(buddy)) {
121 : 0 : __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 [ + - ]: 4140 : if (!isolated_page) {
133 : 4140 : nr_pages = move_freepages_block(zone, page, migratetype, NULL);
134 : 4140 : __mod_zone_freepage_state(zone, nr_pages, migratetype);
135 : : }
136 : 4140 : set_pageblock_migratetype(page, migratetype);
137 : 4140 : zone->nr_isolate_pageblock--;
138 : : out:
139 : : spin_unlock_irqrestore(&zone->lock, flags);
140 [ - + ]: 4140 : if (isolated_page) {
141 : 0 : post_alloc_hook(page, order, __GFP_MOVABLE);
142 : 0 : __free_pages(page, order);
143 : : }
144 : 4140 : }
145 : :
146 : : static inline struct page *
147 : 15939 : __first_valid_page(unsigned long pfn, unsigned long nr_pages)
148 : : {
149 : : int i;
150 : :
151 [ + - ]: 31878 : for (i = 0; i < nr_pages; i++) {
152 : : struct page *page;
153 : :
154 [ + - ]: 15939 : page = pfn_to_online_page(pfn + i);
155 [ - + ]: 15939 : if (!page)
156 : 0 : continue;
157 : 15939 : return page;
158 : : }
159 : : return NULL;
160 : : }
161 : :
162 : : /**
163 : : * start_isolate_page_range() - make page-allocation-type of range of pages to
164 : : * be MIGRATE_ISOLATE.
165 : : * @start_pfn: The lower PFN of the range to be isolated.
166 : : * @end_pfn: The upper PFN of the range to be isolated.
167 : : * start_pfn/end_pfn must be aligned to pageblock_order.
168 : : * @migratetype: Migrate type to set in error recovery.
169 : : * @flags: The following flags are allowed (they can be combined in
170 : : * a bit mask)
171 : : * SKIP_HWPOISON - ignore hwpoison pages
172 : : * REPORT_FAILURE - report details about the failure to
173 : : * isolate the range
174 : : *
175 : : * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
176 : : * the range will never be allocated. Any free pages and pages freed in the
177 : : * future will not be allocated again. If specified range includes migrate types
178 : : * other than MOVABLE or CMA, this will fail with -EBUSY. For isolating all
179 : : * pages in the range finally, the caller have to free all pages in the range.
180 : : * test_page_isolated() can be used for test it.
181 : : *
182 : : * There is no high level synchronization mechanism that prevents two threads
183 : : * from trying to isolate overlapping ranges. If this happens, one thread
184 : : * will notice pageblocks in the overlapping range already set to isolate.
185 : : * This happens in set_migratetype_isolate, and set_migratetype_isolate
186 : : * returns an error. We then clean up by restoring the migration type on
187 : : * pageblocks we may have modified and return -EBUSY to caller. This
188 : : * prevents two threads from simultaneously working on overlapping ranges.
189 : : *
190 : : * Return: the number of isolated pageblocks on success and -EBUSY if any part
191 : : * of range cannot be isolated.
192 : : */
193 : 3726 : int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
194 : : unsigned migratetype, int flags)
195 : : {
196 : : unsigned long pfn;
197 : : unsigned long undo_pfn;
198 : : struct page *page;
199 : : int nr_isolate_pageblock = 0;
200 : :
201 [ - + ]: 3726 : BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
202 [ + - ]: 3726 : BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
203 : :
204 [ + + ]: 7866 : for (pfn = start_pfn;
205 : : pfn < end_pfn;
206 : 4140 : pfn += pageblock_nr_pages) {
207 : 4140 : page = __first_valid_page(pfn, pageblock_nr_pages);
208 [ + - ]: 4140 : if (page) {
209 [ - + ]: 4140 : if (set_migratetype_isolate(page, migratetype, flags)) {
210 : 0 : undo_pfn = pfn;
211 : : goto undo;
212 : : }
213 : 4140 : nr_isolate_pageblock++;
214 : : }
215 : : }
216 : 3726 : return nr_isolate_pageblock;
217 : : undo:
218 [ # # ]: 0 : for (pfn = start_pfn;
219 : : pfn < undo_pfn;
220 : 0 : pfn += pageblock_nr_pages) {
221 [ # # ]: 0 : struct page *page = pfn_to_online_page(pfn);
222 [ # # ]: 0 : if (!page)
223 : 0 : continue;
224 : 0 : unset_migratetype_isolate(page, migratetype);
225 : : }
226 : :
227 : : return -EBUSY;
228 : : }
229 : :
230 : : /*
231 : : * Make isolated pages available again.
232 : : */
233 : 3726 : void undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
234 : : unsigned migratetype)
235 : : {
236 : : unsigned long pfn;
237 : : struct page *page;
238 : :
239 [ - + ]: 3726 : BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
240 [ + - ]: 3726 : BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
241 : :
242 [ + + ]: 7866 : for (pfn = start_pfn;
243 : : pfn < end_pfn;
244 : 4140 : pfn += pageblock_nr_pages) {
245 : 4140 : page = __first_valid_page(pfn, pageblock_nr_pages);
246 [ + - - + ]: 4140 : if (!page || !is_migrate_isolate_page(page))
247 : 0 : continue;
248 : 4140 : unset_migratetype_isolate(page, migratetype);
249 : : }
250 : 3726 : }
251 : : /*
252 : : * Test all pages in the range is free(means isolated) or not.
253 : : * all pages in [start_pfn...end_pfn) must be in the same zone.
254 : : * zone->lock must be held before call this.
255 : : *
256 : : * Returns the last tested pfn.
257 : : */
258 : : static unsigned long
259 : : __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
260 : : bool skip_hwpoisoned_pages)
261 : : {
262 : : struct page *page;
263 : :
264 [ + + ]: 7866 : while (pfn < end_pfn) {
265 : : if (!pfn_valid_within(pfn)) {
266 : : pfn++;
267 : : continue;
268 : : }
269 : 4140 : page = pfn_to_page(pfn);
270 [ + - ]: 4140 : if (PageBuddy(page))
271 : : /*
272 : : * If the page is on a free list, it has to be on
273 : : * the correct MIGRATE_ISOLATE freelist. There is no
274 : : * simple way to verify that as VM_BUG_ON(), though.
275 : : */
276 : 4140 : pfn += 1 << page_order(page);
277 : : else if (skip_hwpoisoned_pages && PageHWPoison(page))
278 : : /* A HWPoisoned page cannot be also PageBuddy */
279 : : pfn++;
280 : : else
281 : : break;
282 : : }
283 : :
284 : 3726 : return pfn;
285 : : }
286 : :
287 : : /* Caller should ensure that requested range is in a single zone */
288 : 3726 : int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
289 : : bool skip_hwpoisoned_pages)
290 : : {
291 : : unsigned long pfn, flags;
292 : : struct page *page;
293 : : struct zone *zone;
294 : :
295 : : /*
296 : : * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
297 : : * are not aligned to pageblock_nr_pages.
298 : : * Then we just check migratetype first.
299 : : */
300 [ + + ]: 7659 : for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
301 : 3933 : page = __first_valid_page(pfn, pageblock_nr_pages);
302 [ + - + - ]: 3933 : if (page && !is_migrate_isolate_page(page))
303 : : break;
304 : : }
305 : 3726 : page = __first_valid_page(start_pfn, end_pfn - start_pfn);
306 [ + - ]: 3726 : if ((pfn < end_pfn) || !page)
307 : : return -EBUSY;
308 : : /* Check all pages are free or marked as ISOLATED */
309 : : zone = page_zone(page);
310 : 3726 : spin_lock_irqsave(&zone->lock, flags);
311 : : pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
312 : : skip_hwpoisoned_pages);
313 : : spin_unlock_irqrestore(&zone->lock, flags);
314 : :
315 : 3726 : trace_test_pages_isolated(start_pfn, end_pfn, pfn);
316 : :
317 [ + - ]: 3726 : return pfn < end_pfn ? -EBUSY : 0;
318 : : }
319 : :
320 : 0 : struct page *alloc_migrate_target(struct page *page, unsigned long private)
321 : : {
322 : 0 : return new_page_nodemask(page, numa_node_id(), &node_states[N_MEMORY]);
323 : : }
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