page_isolation.c revision dbc0e4cefd003834440fe7ac5464616c5235cb94 
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
11static 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 */
36int
37start_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;
56undo:
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 */
68int
69undo_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 */
92static 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
116int 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