Root/mm/page_isolation.c

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 <linux/memory.h>
9#include "internal.h"
10
11/* called while holding zone->lock */
12static void set_pageblock_isolate(struct page *page)
13{
14    if (get_pageblock_migratetype(page) == MIGRATE_ISOLATE)
15        return;
16
17    set_pageblock_migratetype(page, MIGRATE_ISOLATE);
18    page_zone(page)->nr_pageblock_isolate++;
19}
20
21/* called while holding zone->lock */
22static void restore_pageblock_isolate(struct page *page, int migratetype)
23{
24    struct zone *zone = page_zone(page);
25    if (WARN_ON(get_pageblock_migratetype(page) != MIGRATE_ISOLATE))
26        return;
27
28    BUG_ON(zone->nr_pageblock_isolate <= 0);
29    set_pageblock_migratetype(page, migratetype);
30    zone->nr_pageblock_isolate--;
31}
32
33int set_migratetype_isolate(struct page *page)
34{
35    struct zone *zone;
36    unsigned long flags, pfn;
37    struct memory_isolate_notify arg;
38    int notifier_ret;
39    int ret = -EBUSY;
40
41    zone = page_zone(page);
42
43    spin_lock_irqsave(&zone->lock, flags);
44
45    pfn = page_to_pfn(page);
46    arg.start_pfn = pfn;
47    arg.nr_pages = pageblock_nr_pages;
48    arg.pages_found = 0;
49
50    /*
51     * It may be possible to isolate a pageblock even if the
52     * migratetype is not MIGRATE_MOVABLE. The memory isolation
53     * notifier chain is used by balloon drivers to return the
54     * number of pages in a range that are held by the balloon
55     * driver to shrink memory. If all the pages are accounted for
56     * by balloons, are free, or on the LRU, isolation can continue.
57     * Later, for example, when memory hotplug notifier runs, these
58     * pages reported as "can be isolated" should be isolated(freed)
59     * by the balloon driver through the memory notifier chain.
60     */
61    notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
62    notifier_ret = notifier_to_errno(notifier_ret);
63    if (notifier_ret)
64        goto out;
65    /*
66     * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
67     * We just check MOVABLE pages.
68     */
69    if (!has_unmovable_pages(zone, page, arg.pages_found))
70        ret = 0;
71
72    /*
73     * immobile means "not-on-lru" paes. If immobile is larger than
74     * removable-by-driver pages reported by notifier, we'll fail.
75     */
76
77out:
78    if (!ret) {
79        set_pageblock_isolate(page);
80        move_freepages_block(zone, page, MIGRATE_ISOLATE);
81    }
82
83    spin_unlock_irqrestore(&zone->lock, flags);
84    if (!ret)
85        drain_all_pages();
86    return ret;
87}
88
89void unset_migratetype_isolate(struct page *page, unsigned migratetype)
90{
91    struct zone *zone;
92    unsigned long flags;
93    zone = page_zone(page);
94    spin_lock_irqsave(&zone->lock, flags);
95    if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
96        goto out;
97    move_freepages_block(zone, page, migratetype);
98    restore_pageblock_isolate(page, migratetype);
99out:
100    spin_unlock_irqrestore(&zone->lock, flags);
101}
102
103static inline struct page *
104__first_valid_page(unsigned long pfn, unsigned long nr_pages)
105{
106    int i;
107    for (i = 0; i < nr_pages; i++)
108        if (pfn_valid_within(pfn + i))
109            break;
110    if (unlikely(i == nr_pages))
111        return NULL;
112    return pfn_to_page(pfn + i);
113}
114
115/*
116 * start_isolate_page_range() -- make page-allocation-type of range of pages
117 * to be MIGRATE_ISOLATE.
118 * @start_pfn: The lower PFN of the range to be isolated.
119 * @end_pfn: The upper PFN of the range to be isolated.
120 * @migratetype: migrate type to set in error recovery.
121 *
122 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
123 * the range will never be allocated. Any free pages and pages freed in the
124 * future will not be allocated again.
125 *
126 * start_pfn/end_pfn must be aligned to pageblock_order.
127 * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
128 */
129int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
130                 unsigned migratetype)
131{
132    unsigned long pfn;
133    unsigned long undo_pfn;
134    struct page *page;
135
136    BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
137    BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
138
139    for (pfn = start_pfn;
140         pfn < end_pfn;
141         pfn += pageblock_nr_pages) {
142        page = __first_valid_page(pfn, pageblock_nr_pages);
143        if (page && set_migratetype_isolate(page)) {
144            undo_pfn = pfn;
145            goto undo;
146        }
147    }
148    return 0;
149undo:
150    for (pfn = start_pfn;
151         pfn < undo_pfn;
152         pfn += pageblock_nr_pages)
153        unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
154
155    return -EBUSY;
156}
157
158/*
159 * Make isolated pages available again.
160 */
161int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
162                unsigned migratetype)
163{
164    unsigned long pfn;
165    struct page *page;
166    BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
167    BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
168    for (pfn = start_pfn;
169         pfn < end_pfn;
170         pfn += pageblock_nr_pages) {
171        page = __first_valid_page(pfn, pageblock_nr_pages);
172        if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
173            continue;
174        unset_migratetype_isolate(page, migratetype);
175    }
176    return 0;
177}
178/*
179 * Test all pages in the range is free(means isolated) or not.
180 * all pages in [start_pfn...end_pfn) must be in the same zone.
181 * zone->lock must be held before call this.
182 *
183 * Returns 1 if all pages in the range are isolated.
184 */
185static int
186__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
187{
188    struct page *page;
189
190    while (pfn < end_pfn) {
191        if (!pfn_valid_within(pfn)) {
192            pfn++;
193            continue;
194        }
195        page = pfn_to_page(pfn);
196        if (PageBuddy(page))
197            pfn += 1 << page_order(page);
198        else if (page_count(page) == 0 &&
199                page_private(page) == MIGRATE_ISOLATE)
200            pfn += 1;
201        else
202            break;
203    }
204    if (pfn < end_pfn)
205        return 0;
206    return 1;
207}
208
209int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
210{
211    unsigned long pfn, flags;
212    struct page *page;
213    struct zone *zone;
214    int ret;
215
216    /*
217     * Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
218     * is not aligned to pageblock_nr_pages.
219     * Then we just check pagetype fist.
220     */
221    for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
222        page = __first_valid_page(pfn, pageblock_nr_pages);
223        if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
224            break;
225    }
226    page = __first_valid_page(start_pfn, end_pfn - start_pfn);
227    if ((pfn < end_pfn) || !page)
228        return -EBUSY;
229    /* Check all pages are free or Marked as ISOLATED */
230    zone = page_zone(page);
231    spin_lock_irqsave(&zone->lock, flags);
232    ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn);
233    spin_unlock_irqrestore(&zone->lock, flags);
234    return ret ? 0 : -EBUSY;
235}
236

Archive Download this file

Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master

Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9



interactive