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 "internal.h"
9
10 static inline struct page *
__first_valid_page(unsigned long pfn,unsigned long nr_pages)11 __first_valid_page(unsigned long pfn, unsigned long nr_pages)
12 {
13 int i;
14 for (i = 0; i < nr_pages; i++)
15 if (pfn_valid_within(pfn + i))
16 break;
17 if (unlikely(i == nr_pages))
18 return NULL;
19 return pfn_to_page(pfn + i);
20 }
21
22 /*
23 * start_isolate_page_range() -- make page-allocation-type of range of pages
24 * to be MIGRATE_ISOLATE.
25 * @start_pfn: The lower PFN of the range to be isolated.
26 * @end_pfn: The upper PFN of the range to be isolated.
27 *
28 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
29 * the range will never be allocated. Any free pages and pages freed in the
30 * future will not be allocated again.
31 *
32 * start_pfn/end_pfn must be aligned to pageblock_order.
33 * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
34 */
35 int
start_isolate_page_range(unsigned long start_pfn,unsigned long end_pfn)36 start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
37 {
38 unsigned long pfn;
39 unsigned long undo_pfn;
40 struct page *page;
41
42 BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
43 BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
44
45 for (pfn = start_pfn;
46 pfn < end_pfn;
47 pfn += pageblock_nr_pages) {
48 page = __first_valid_page(pfn, pageblock_nr_pages);
49 if (page && set_migratetype_isolate(page)) {
50 undo_pfn = pfn;
51 goto undo;
52 }
53 }
54 return 0;
55 undo:
56 for (pfn = start_pfn;
57 pfn < undo_pfn;
58 pfn += pageblock_nr_pages)
59 unset_migratetype_isolate(pfn_to_page(pfn));
60
61 return -EBUSY;
62 }
63
64 /*
65 * Make isolated pages available again.
66 */
67 int
undo_isolate_page_range(unsigned long start_pfn,unsigned long end_pfn)68 undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
69 {
70 unsigned long pfn;
71 struct page *page;
72 BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
73 BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
74 for (pfn = start_pfn;
75 pfn < end_pfn;
76 pfn += pageblock_nr_pages) {
77 page = __first_valid_page(pfn, pageblock_nr_pages);
78 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
79 continue;
80 unset_migratetype_isolate(page);
81 }
82 return 0;
83 }
84 /*
85 * Test all pages in the range is free(means isolated) or not.
86 * all pages in [start_pfn...end_pfn) must be in the same zone.
87 * zone->lock must be held before call this.
88 *
89 * Returns 0 if all pages in the range is isolated.
90 */
91 static int
__test_page_isolated_in_pageblock(unsigned long pfn,unsigned long end_pfn)92 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
93 {
94 struct page *page;
95
96 while (pfn < end_pfn) {
97 if (!pfn_valid_within(pfn)) {
98 pfn++;
99 continue;
100 }
101 page = pfn_to_page(pfn);
102 if (PageBuddy(page))
103 pfn += 1 << page_order(page);
104 else if (page_count(page) == 0 &&
105 page_private(page) == MIGRATE_ISOLATE)
106 pfn += 1;
107 else
108 break;
109 }
110 if (pfn < end_pfn)
111 return 0;
112 return 1;
113 }
114
test_pages_isolated(unsigned long start_pfn,unsigned long end_pfn)115 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
116 {
117 unsigned long pfn, flags;
118 struct page *page;
119 struct zone *zone;
120 int ret;
121
122 pfn = start_pfn;
123 /*
124 * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
125 * is not aligned to pageblock_nr_pages.
126 * Then we just check pagetype fist.
127 */
128 for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
129 page = __first_valid_page(pfn, pageblock_nr_pages);
130 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
131 break;
132 }
133 page = __first_valid_page(start_pfn, end_pfn - start_pfn);
134 if ((pfn < end_pfn) || !page)
135 return -EBUSY;
136 /* Check all pages are free or Marked as ISOLATED */
137 zone = page_zone(page);
138 spin_lock_irqsave(&zone->lock, flags);
139 ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn);
140 spin_unlock_irqrestore(&zone->lock, flags);
141 return ret ? 0 : -EBUSY;
142 }
143