page_isolation.c revision a70dcb969f64e2fa98c24f47854f20bf02ff0092 
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
10static 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 */
35int
36start_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;
55undo:
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 */
67int
68undo_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 */
91static 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
115int 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