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>
10 #include <linux/page_owner.h>
13 #define CREATE_TRACE_POINTS
14 #include <trace/events/page_isolation.h>
16 static int set_migratetype_isolate(struct page
*page
,
17 bool skip_hwpoisoned_pages
)
20 unsigned long flags
, pfn
;
21 struct memory_isolate_notify arg
;
25 zone
= page_zone(page
);
27 spin_lock_irqsave(&zone
->lock
, flags
);
29 pfn
= page_to_pfn(page
);
31 arg
.nr_pages
= pageblock_nr_pages
;
35 * It may be possible to isolate a pageblock even if the
36 * migratetype is not MIGRATE_MOVABLE. The memory isolation
37 * notifier chain is used by balloon drivers to return the
38 * number of pages in a range that are held by the balloon
39 * driver to shrink memory. If all the pages are accounted for
40 * by balloons, are free, or on the LRU, isolation can continue.
41 * Later, for example, when memory hotplug notifier runs, these
42 * pages reported as "can be isolated" should be isolated(freed)
43 * by the balloon driver through the memory notifier chain.
45 notifier_ret
= memory_isolate_notify(MEM_ISOLATE_COUNT
, &arg
);
46 notifier_ret
= notifier_to_errno(notifier_ret
);
50 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
51 * We just check MOVABLE pages.
53 if (!has_unmovable_pages(zone
, page
, arg
.pages_found
,
54 skip_hwpoisoned_pages
))
58 * immobile means "not-on-lru" pages. If immobile is larger than
59 * removable-by-driver pages reported by notifier, we'll fail.
64 unsigned long nr_pages
;
65 int migratetype
= get_pageblock_migratetype(page
);
67 set_pageblock_migratetype(page
, MIGRATE_ISOLATE
);
68 zone
->nr_isolate_pageblock
++;
69 nr_pages
= move_freepages_block(zone
, page
, MIGRATE_ISOLATE
,
72 __mod_zone_freepage_state(zone
, -nr_pages
, migratetype
);
75 spin_unlock_irqrestore(&zone
->lock
, flags
);
77 drain_all_pages(zone
);
81 static void unset_migratetype_isolate(struct page
*page
, unsigned migratetype
)
84 unsigned long flags
, nr_pages
;
85 bool isolated_page
= false;
87 unsigned long pfn
, buddy_pfn
;
90 zone
= page_zone(page
);
91 spin_lock_irqsave(&zone
->lock
, flags
);
92 if (!is_migrate_isolate_page(page
))
96 * Because freepage with more than pageblock_order on isolated
97 * pageblock is restricted to merge due to freepage counting problem,
98 * it is possible that there is free buddy page.
99 * move_freepages_block() doesn't care of merge so we need other
100 * approach in order to merge them. Isolation and free will make
101 * these pages to be merged.
103 if (PageBuddy(page
)) {
104 order
= page_order(page
);
105 if (order
>= pageblock_order
) {
106 pfn
= page_to_pfn(page
);
107 buddy_pfn
= __find_buddy_pfn(pfn
, order
);
108 buddy
= page
+ (buddy_pfn
- pfn
);
110 if (pfn_valid_within(buddy_pfn
) &&
111 !is_migrate_isolate_page(buddy
)) {
112 __isolate_free_page(page
, order
);
113 isolated_page
= true;
119 * If we isolate freepage with more than pageblock_order, there
120 * should be no freepage in the range, so we could avoid costly
121 * pageblock scanning for freepage moving.
123 if (!isolated_page
) {
124 nr_pages
= move_freepages_block(zone
, page
, migratetype
, NULL
);
125 __mod_zone_freepage_state(zone
, nr_pages
, migratetype
);
127 set_pageblock_migratetype(page
, migratetype
);
128 zone
->nr_isolate_pageblock
--;
130 spin_unlock_irqrestore(&zone
->lock
, flags
);
132 post_alloc_hook(page
, order
, __GFP_MOVABLE
);
133 __free_pages(page
, order
);
137 static inline struct page
*
138 __first_valid_page(unsigned long pfn
, unsigned long nr_pages
)
142 for (i
= 0; i
< nr_pages
; i
++) {
145 if (!pfn_valid_within(pfn
+ i
))
147 page
= pfn_to_online_page(pfn
+ i
);
156 * start_isolate_page_range() -- make page-allocation-type of range of pages
157 * to be MIGRATE_ISOLATE.
158 * @start_pfn: The lower PFN of the range to be isolated.
159 * @end_pfn: The upper PFN of the range to be isolated.
160 * @migratetype: migrate type to set in error recovery.
162 * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
163 * the range will never be allocated. Any free pages and pages freed in the
164 * future will not be allocated again.
166 * start_pfn/end_pfn must be aligned to pageblock_order.
167 * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
169 int start_isolate_page_range(unsigned long start_pfn
, unsigned long end_pfn
,
170 unsigned migratetype
, bool skip_hwpoisoned_pages
)
173 unsigned long undo_pfn
;
176 BUG_ON(!IS_ALIGNED(start_pfn
, pageblock_nr_pages
));
177 BUG_ON(!IS_ALIGNED(end_pfn
, pageblock_nr_pages
));
179 for (pfn
= start_pfn
;
181 pfn
+= pageblock_nr_pages
) {
182 page
= __first_valid_page(pfn
, pageblock_nr_pages
);
184 set_migratetype_isolate(page
, skip_hwpoisoned_pages
)) {
191 for (pfn
= start_pfn
;
193 pfn
+= pageblock_nr_pages
) {
194 struct page
*page
= pfn_to_online_page(pfn
);
197 unset_migratetype_isolate(page
, migratetype
);
204 * Make isolated pages available again.
206 int undo_isolate_page_range(unsigned long start_pfn
, unsigned long end_pfn
,
207 unsigned migratetype
)
212 BUG_ON(!IS_ALIGNED(start_pfn
, pageblock_nr_pages
));
213 BUG_ON(!IS_ALIGNED(end_pfn
, pageblock_nr_pages
));
215 for (pfn
= start_pfn
;
217 pfn
+= pageblock_nr_pages
) {
218 page
= __first_valid_page(pfn
, pageblock_nr_pages
);
219 if (!page
|| !is_migrate_isolate_page(page
))
221 unset_migratetype_isolate(page
, migratetype
);
226 * Test all pages in the range is free(means isolated) or not.
227 * all pages in [start_pfn...end_pfn) must be in the same zone.
228 * zone->lock must be held before call this.
230 * Returns the last tested pfn.
233 __test_page_isolated_in_pageblock(unsigned long pfn
, unsigned long end_pfn
,
234 bool skip_hwpoisoned_pages
)
238 while (pfn
< end_pfn
) {
239 if (!pfn_valid_within(pfn
)) {
243 page
= pfn_to_page(pfn
);
246 * If the page is on a free list, it has to be on
247 * the correct MIGRATE_ISOLATE freelist. There is no
248 * simple way to verify that as VM_BUG_ON(), though.
250 pfn
+= 1 << page_order(page
);
251 else if (skip_hwpoisoned_pages
&& PageHWPoison(page
))
252 /* A HWPoisoned page cannot be also PageBuddy */
261 /* Caller should ensure that requested range is in a single zone */
262 int test_pages_isolated(unsigned long start_pfn
, unsigned long end_pfn
,
263 bool skip_hwpoisoned_pages
)
265 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
&& !is_migrate_isolate_page(page
))
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 pfn
= __test_page_isolated_in_pageblock(start_pfn
, end_pfn
,
286 skip_hwpoisoned_pages
);
287 spin_unlock_irqrestore(&zone
->lock
, flags
);
289 trace_test_pages_isolated(start_pfn
, end_pfn
, pfn
);
291 return pfn
< end_pfn
? -EBUSY
: 0;
294 struct page
*alloc_migrate_target(struct page
*page
, unsigned long private,
297 gfp_t gfp_mask
= GFP_USER
| __GFP_MOVABLE
;
300 * TODO: allocate a destination hugepage from a nearest neighbor node,
301 * accordance with memory policy of the user process if possible. For
302 * now as a simple work-around, we use the next node for destination.
305 return alloc_huge_page_node(page_hstate(compound_head(page
)),
306 next_node_in(page_to_nid(page
),
309 if (PageHighMem(page
))
310 gfp_mask
|= __GFP_HIGHMEM
;
312 return alloc_page(gfp_mask
);