xref: /openbmc/linux/mm/page_isolation.c (revision 643d1f7f) 
1 /*
2  * linux/mm/page_isolation.c
3  */
4 
5 #include <stddef.h>
6 #include <linux/mm.h>
7 #include <linux/page-isolation.h>
8 #include <linux/pageblock-flags.h>
9 #include "internal.h"
10 
11 static inline struct page *
12 __first_valid_page(unsigned long pfn, unsigned long nr_pages)
13 {
14 	int i;
15 	for (i = 0; i < nr_pages; i++)
16 		if (pfn_valid_within(pfn + i))
17 			break;
18 	if (unlikely(i == nr_pages))
19 		return NULL;
20 	return pfn_to_page(pfn + i);
21 }
22 
23 /*
24  * start_isolate_page_range() -- make page-allocation-type of range of pages
25  * to be MIGRATE_ISOLATE.
26  * @start_pfn: The lower PFN of the range to be isolated.
27  * @end_pfn: The upper PFN of the range to be isolated.
28  *
29  * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
30  * the range will never be allocated. Any free pages and pages freed in the
31  * future will not be allocated again.
32  *
33  * start_pfn/end_pfn must be aligned to pageblock_order.
34  * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
35  */
36 int
37 start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
38 {
39 	unsigned long pfn;
40 	unsigned long undo_pfn;
41 	struct page *page;
42 
43 	BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
44 	BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
45 
46 	for (pfn = start_pfn;
47 	     pfn < end_pfn;
48 	     pfn += pageblock_nr_pages) {
49 		page = __first_valid_page(pfn, pageblock_nr_pages);
50 		if (page && set_migratetype_isolate(page)) {
51 			undo_pfn = pfn;
52 			goto undo;
53 		}
54 	}
55 	return 0;
56 undo:
57 	for (pfn = start_pfn;
58 	     pfn < undo_pfn;
59 	     pfn += pageblock_nr_pages)
60 		unset_migratetype_isolate(pfn_to_page(pfn));
61 
62 	return -EBUSY;
63 }
64 
65 /*
66  * Make isolated pages available again.
67  */
68 int
69 undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
70 {
71 	unsigned long pfn;
72 	struct page *page;
73 	BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
74 	BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
75 	for (pfn = start_pfn;
76 	     pfn < end_pfn;
77 	     pfn += pageblock_nr_pages) {
78 		page = __first_valid_page(pfn, pageblock_nr_pages);
79 		if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
80 			continue;
81 		unset_migratetype_isolate(page);
82 	}
83 	return 0;
84 }
85 /*
86  * Test all pages in the range is free(means isolated) or not.
87  * all pages in [start_pfn...end_pfn) must be in the same zone.
88  * zone->lock must be held before call this.
89  *
90  * Returns 0 if all pages in the range is isolated.
91  */
92 static int
93 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
94 {
95 	struct page *page;
96 
97 	while (pfn < end_pfn) {
98 		if (!pfn_valid_within(pfn)) {
99 			pfn++;
100 			continue;
101 		}
102 		page = pfn_to_page(pfn);
103 		if (PageBuddy(page))
104 			pfn += 1 << page_order(page);
105 		else if (page_count(page) == 0 &&
106 				page_private(page) == MIGRATE_ISOLATE)
107 			pfn += 1;
108 		else
109 			break;
110 	}
111 	if (pfn < end_pfn)
112 		return 0;
113 	return 1;
114 }
115 
116 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
117 {
118 	unsigned long pfn;
119 	struct page *page;
120 
121 	pfn = start_pfn;
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 	if (pfn < end_pfn)
133 		return -EBUSY;
134 	/* Check all pages are free or Marked as ISOLATED */
135 	if (__test_page_isolated_in_pageblock(start_pfn, end_pfn))
136 		return 0;
137 	return -EBUSY;
138 }
139