2 * linux/mm/page_isolation.c
6 #include <linux/page-isolation.h>
7 #include <linux/pageblock-flags.h>
8 #include <linux/memory.h>
11 /* called while holding zone->lock */
12 static void set_pageblock_isolate(struct page *page)
14 if (get_pageblock_migratetype(page) == MIGRATE_ISOLATE)
17 set_pageblock_migratetype(page, MIGRATE_ISOLATE);
18 page_zone(page)->nr_pageblock_isolate++;
21 /* called while holding zone->lock */
22 static void restore_pageblock_isolate(struct page *page, int migratetype)
24 struct zone *zone = page_zone(page);
25 if (WARN_ON(get_pageblock_migratetype(page) != MIGRATE_ISOLATE))
28 BUG_ON(zone->nr_pageblock_isolate <= 0);
29 set_pageblock_migratetype(page, migratetype);
30 zone->nr_pageblock_isolate--;
33 int set_migratetype_isolate(struct page *page)
36 unsigned long flags, pfn;
37 struct memory_isolate_notify arg;
41 zone = page_zone(page);
43 spin_lock_irqsave(&zone->lock, flags);
45 pfn = page_to_pfn(page);
47 arg.nr_pages = pageblock_nr_pages;
51 * It may be possible to isolate a pageblock even if the
52 * migratetype is not MIGRATE_MOVABLE. The memory isolation
53 * notifier chain is used by balloon drivers to return the
54 * number of pages in a range that are held by the balloon
55 * driver to shrink memory. If all the pages are accounted for
56 * by balloons, are free, or on the LRU, isolation can continue.
57 * Later, for example, when memory hotplug notifier runs, these
58 * pages reported as "can be isolated" should be isolated(freed)
59 * by the balloon driver through the memory notifier chain.
61 notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
62 notifier_ret = notifier_to_errno(notifier_ret);
66 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
67 * We just check MOVABLE pages.
69 if (!has_unmovable_pages(zone, page, arg.pages_found))
73 * immobile means "not-on-lru" paes. If immobile is larger than
74 * removable-by-driver pages reported by notifier, we'll fail.
79 unsigned long nr_pages;
81 set_pageblock_isolate(page);
82 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
84 __mod_zone_page_state(zone, NR_FREE_PAGES, -nr_pages);
87 spin_unlock_irqrestore(&zone->lock, flags);
93 void unset_migratetype_isolate(struct page *page, unsigned migratetype)
96 unsigned long flags, nr_pages;
98 zone = page_zone(page);
99 spin_lock_irqsave(&zone->lock, flags);
100 if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
102 nr_pages = move_freepages_block(zone, page, migratetype);
103 __mod_zone_page_state(zone, NR_FREE_PAGES, nr_pages);
104 restore_pageblock_isolate(page, migratetype);
106 spin_unlock_irqrestore(&zone->lock, flags);
109 static inline struct page *
110 __first_valid_page(unsigned long pfn, unsigned long nr_pages)
113 for (i = 0; i < nr_pages; i++)
114 if (pfn_valid_within(pfn + i))
116 if (unlikely(i == nr_pages))
118 return pfn_to_page(pfn + i);
122 * start_isolate_page_range() -- make page-allocation-type of range of pages
123 * to be MIGRATE_ISOLATE.
124 * @start_pfn: The lower PFN of the range to be isolated.
125 * @end_pfn: The upper PFN of the range to be isolated.
126 * @migratetype: migrate type to set in error recovery.
128 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
129 * the range will never be allocated. Any free pages and pages freed in the
130 * future will not be allocated again.
132 * start_pfn/end_pfn must be aligned to pageblock_order.
133 * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
135 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
136 unsigned migratetype)
139 unsigned long undo_pfn;
142 BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
143 BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
145 for (pfn = start_pfn;
147 pfn += pageblock_nr_pages) {
148 page = __first_valid_page(pfn, pageblock_nr_pages);
149 if (page && set_migratetype_isolate(page)) {
156 for (pfn = start_pfn;
158 pfn += pageblock_nr_pages)
159 unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
165 * Make isolated pages available again.
167 int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
168 unsigned migratetype)
172 BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
173 BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
174 for (pfn = start_pfn;
176 pfn += pageblock_nr_pages) {
177 page = __first_valid_page(pfn, pageblock_nr_pages);
178 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
180 unset_migratetype_isolate(page, migratetype);
185 * Test all pages in the range is free(means isolated) or not.
186 * all pages in [start_pfn...end_pfn) must be in the same zone.
187 * zone->lock must be held before call this.
189 * Returns 1 if all pages in the range are isolated.
192 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
196 while (pfn < end_pfn) {
197 if (!pfn_valid_within(pfn)) {
201 page = pfn_to_page(pfn);
203 pfn += 1 << page_order(page);
204 else if (page_count(page) == 0 &&
205 page_private(page) == MIGRATE_ISOLATE)
215 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
217 unsigned long pfn, flags;
223 * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
224 * is not aligned to pageblock_nr_pages.
225 * Then we just check pagetype fist.
227 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
228 page = __first_valid_page(pfn, pageblock_nr_pages);
229 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
232 page = __first_valid_page(start_pfn, end_pfn - start_pfn);
233 if ((pfn < end_pfn) || !page)
235 /* Check all pages are free or Marked as ISOLATED */
236 zone = page_zone(page);
237 spin_lock_irqsave(&zone->lock, flags);
238 ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn);
239 spin_unlock_irqrestore(&zone->lock, flags);
240 return ret ? 0 : -EBUSY;