Root/
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 * |
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 |
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 |
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 1 if all pages in the range is isolated. |
90 | */ |
91 | static int |
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 | |
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 | /* |
123 | * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page |
124 | * is not aligned to pageblock_nr_pages. |
125 | * Then we just check pagetype fist. |
126 | */ |
127 | for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) { |
128 | page = __first_valid_page(pfn, pageblock_nr_pages); |
129 | if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE) |
130 | break; |
131 | } |
132 | page = __first_valid_page(start_pfn, end_pfn - start_pfn); |
133 | if ((pfn < end_pfn) || !page) |
134 | return -EBUSY; |
135 | /* Check all pages are free or Marked as ISOLATED */ |
136 | zone = page_zone(page); |
137 | spin_lock_irqsave(&zone->lock, flags); |
138 | ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn); |
139 | spin_unlock_irqrestore(&zone->lock, flags); |
140 | return ret ? 0 : -EBUSY; |
141 | } |
142 |
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