2 * linux/mm/page_isolation.c
6 #include <linux/page-isolation.h>
7 #include <linux/pageblock-flags.h>
8 #include <linux/memory.h>
9 #include <linux/hugetlb.h>
12 int set_migratetype_isolate(struct page
*page
, bool skip_hwpoisoned_pages
)
15 unsigned long flags
, pfn
;
16 struct memory_isolate_notify arg
;
20 zone
= page_zone(page
);
22 spin_lock_irqsave(&zone
->lock
, flags
);
24 pfn
= page_to_pfn(page
);
26 arg
.nr_pages
= pageblock_nr_pages
;
30 * It may be possible to isolate a pageblock even if the
31 * migratetype is not MIGRATE_MOVABLE. The memory isolation
32 * notifier chain is used by balloon drivers to return the
33 * number of pages in a range that are held by the balloon
34 * driver to shrink memory. If all the pages are accounted for
35 * by balloons, are free, or on the LRU, isolation can continue.
36 * Later, for example, when memory hotplug notifier runs, these
37 * pages reported as "can be isolated" should be isolated(freed)
38 * by the balloon driver through the memory notifier chain.
40 notifier_ret
= memory_isolate_notify(MEM_ISOLATE_COUNT
, &arg
);
41 notifier_ret
= notifier_to_errno(notifier_ret
);
45 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
46 * We just check MOVABLE pages.
48 if (!has_unmovable_pages(zone
, page
, arg
.pages_found
,
49 skip_hwpoisoned_pages
))
53 * immobile means "not-on-lru" paes. If immobile is larger than
54 * removable-by-driver pages reported by notifier, we'll fail.
59 unsigned long nr_pages
;
60 int migratetype
= get_pageblock_migratetype(page
);
62 set_pageblock_migratetype(page
, MIGRATE_ISOLATE
);
63 zone
->nr_isolate_pageblock
++;
64 nr_pages
= move_freepages_block(zone
, page
, MIGRATE_ISOLATE
);
66 __mod_zone_freepage_state(zone
, -nr_pages
, migratetype
);
69 spin_unlock_irqrestore(&zone
->lock
, flags
);
71 drain_all_pages(zone
);
75 void unset_migratetype_isolate(struct page
*page
, unsigned migratetype
)
78 unsigned long flags
, nr_pages
;
79 struct page
*isolated_page
= NULL
;
81 unsigned long page_idx
, buddy_idx
;
84 zone
= page_zone(page
);
85 spin_lock_irqsave(&zone
->lock
, flags
);
86 if (get_pageblock_migratetype(page
) != MIGRATE_ISOLATE
)
90 * Because freepage with more than pageblock_order on isolated
91 * pageblock is restricted to merge due to freepage counting problem,
92 * it is possible that there is free buddy page.
93 * move_freepages_block() doesn't care of merge so we need other
94 * approach in order to merge them. Isolation and free will make
95 * these pages to be merged.
97 if (PageBuddy(page
)) {
98 order
= page_order(page
);
99 if (order
>= pageblock_order
) {
100 page_idx
= page_to_pfn(page
) & ((1 << MAX_ORDER
) - 1);
101 buddy_idx
= __find_buddy_index(page_idx
, order
);
102 buddy
= page
+ (buddy_idx
- page_idx
);
104 if (!is_migrate_isolate_page(buddy
)) {
105 __isolate_free_page(page
, order
);
106 kernel_map_pages(page
, (1 << order
), 1);
107 set_page_refcounted(page
);
108 isolated_page
= page
;
114 * If we isolate freepage with more than pageblock_order, there
115 * should be no freepage in the range, so we could avoid costly
116 * pageblock scanning for freepage moving.
118 if (!isolated_page
) {
119 nr_pages
= move_freepages_block(zone
, page
, migratetype
);
120 __mod_zone_freepage_state(zone
, nr_pages
, migratetype
);
122 set_pageblock_migratetype(page
, migratetype
);
123 zone
->nr_isolate_pageblock
--;
125 spin_unlock_irqrestore(&zone
->lock
, flags
);
127 __free_pages(isolated_page
, order
);
130 static inline struct page
*
131 __first_valid_page(unsigned long pfn
, unsigned long nr_pages
)
134 for (i
= 0; i
< nr_pages
; i
++)
135 if (pfn_valid_within(pfn
+ i
))
137 if (unlikely(i
== nr_pages
))
139 return pfn_to_page(pfn
+ i
);
143 * start_isolate_page_range() -- make page-allocation-type of range of pages
144 * to be MIGRATE_ISOLATE.
145 * @start_pfn: The lower PFN of the range to be isolated.
146 * @end_pfn: The upper PFN of the range to be isolated.
147 * @migratetype: migrate type to set in error recovery.
149 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
150 * the range will never be allocated. Any free pages and pages freed in the
151 * future will not be allocated again.
153 * start_pfn/end_pfn must be aligned to pageblock_order.
154 * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
156 int start_isolate_page_range(unsigned long start_pfn
, unsigned long end_pfn
,
157 unsigned migratetype
, bool skip_hwpoisoned_pages
)
160 unsigned long undo_pfn
;
163 BUG_ON((start_pfn
) & (pageblock_nr_pages
- 1));
164 BUG_ON((end_pfn
) & (pageblock_nr_pages
- 1));
166 for (pfn
= start_pfn
;
168 pfn
+= pageblock_nr_pages
) {
169 page
= __first_valid_page(pfn
, pageblock_nr_pages
);
171 set_migratetype_isolate(page
, skip_hwpoisoned_pages
)) {
178 for (pfn
= start_pfn
;
180 pfn
+= pageblock_nr_pages
)
181 unset_migratetype_isolate(pfn_to_page(pfn
), migratetype
);
187 * Make isolated pages available again.
189 int undo_isolate_page_range(unsigned long start_pfn
, unsigned long end_pfn
,
190 unsigned migratetype
)
194 BUG_ON((start_pfn
) & (pageblock_nr_pages
- 1));
195 BUG_ON((end_pfn
) & (pageblock_nr_pages
- 1));
196 for (pfn
= start_pfn
;
198 pfn
+= pageblock_nr_pages
) {
199 page
= __first_valid_page(pfn
, pageblock_nr_pages
);
200 if (!page
|| get_pageblock_migratetype(page
) != MIGRATE_ISOLATE
)
202 unset_migratetype_isolate(page
, migratetype
);
207 * Test all pages in the range is free(means isolated) or not.
208 * all pages in [start_pfn...end_pfn) must be in the same zone.
209 * zone->lock must be held before call this.
211 * Returns 1 if all pages in the range are isolated.
214 __test_page_isolated_in_pageblock(unsigned long pfn
, unsigned long end_pfn
,
215 bool skip_hwpoisoned_pages
)
219 while (pfn
< end_pfn
) {
220 if (!pfn_valid_within(pfn
)) {
224 page
= pfn_to_page(pfn
);
225 if (PageBuddy(page
)) {
227 * If race between isolatation and allocation happens,
228 * some free pages could be in MIGRATE_MOVABLE list
229 * although pageblock's migratation type of the page
230 * is MIGRATE_ISOLATE. Catch it and move the page into
231 * MIGRATE_ISOLATE list.
233 if (get_freepage_migratetype(page
) != MIGRATE_ISOLATE
) {
234 struct page
*end_page
;
236 end_page
= page
+ (1 << page_order(page
)) - 1;
237 move_freepages(page_zone(page
), page
, end_page
,
240 pfn
+= 1 << page_order(page
);
242 else if (page_count(page
) == 0 &&
243 get_freepage_migratetype(page
) == MIGRATE_ISOLATE
)
245 else if (skip_hwpoisoned_pages
&& PageHWPoison(page
)) {
247 * The HWPoisoned page may be not in buddy
248 * system, and page_count() is not 0.
261 int test_pages_isolated(unsigned long start_pfn
, unsigned long end_pfn
,
262 bool skip_hwpoisoned_pages
)
264 unsigned long pfn
, flags
;
270 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
271 * are not aligned to pageblock_nr_pages.
272 * Then we just check migratetype first.
274 for (pfn
= start_pfn
; pfn
< end_pfn
; pfn
+= pageblock_nr_pages
) {
275 page
= __first_valid_page(pfn
, pageblock_nr_pages
);
276 if (page
&& get_pageblock_migratetype(page
) != MIGRATE_ISOLATE
)
279 page
= __first_valid_page(start_pfn
, end_pfn
- start_pfn
);
280 if ((pfn
< end_pfn
) || !page
)
282 /* Check all pages are free or marked as ISOLATED */
283 zone
= page_zone(page
);
284 spin_lock_irqsave(&zone
->lock
, flags
);
285 ret
= __test_page_isolated_in_pageblock(start_pfn
, end_pfn
,
286 skip_hwpoisoned_pages
);
287 spin_unlock_irqrestore(&zone
->lock
, flags
);
288 return ret
? 0 : -EBUSY
;
291 struct page
*alloc_migrate_target(struct page
*page
, unsigned long private,
294 gfp_t gfp_mask
= GFP_USER
| __GFP_MOVABLE
;
297 * TODO: allocate a destination hugepage from a nearest neighbor node,
298 * accordance with memory policy of the user process if possible. For
299 * now as a simple work-around, we use the next node for destination.
301 if (PageHuge(page
)) {
302 nodemask_t src
= nodemask_of_node(page_to_nid(page
));
304 nodes_complement(dst
, src
);
305 return alloc_huge_page_node(page_hstate(compound_head(page
)),
306 next_node(page_to_nid(page
), dst
));
309 if (PageHighMem(page
))
310 gfp_mask
|= __GFP_HIGHMEM
;
312 return alloc_page(gfp_mask
);