Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/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 <linux/hugetlb.h>
 10 #include <linux/page_owner.h>
 11 #include "internal.h"
 12 
 13 #define CREATE_TRACE_POINTS
 14 #include <trace/events/page_isolation.h>
 15 
 16 static int set_migratetype_isolate(struct page *page,
 17                                 bool skip_hwpoisoned_pages)
 18 {
 19         struct zone *zone;
 20         unsigned long flags, pfn;
 21         struct memory_isolate_notify arg;
 22         int notifier_ret;
 23         int ret = -EBUSY;
 24 
 25         zone = page_zone(page);
 26 
 27         spin_lock_irqsave(&zone->lock, flags);
 28 
 29         pfn = page_to_pfn(page);
 30         arg.start_pfn = pfn;
 31         arg.nr_pages = pageblock_nr_pages;
 32         arg.pages_found = 0;
 33 
 34         /*
 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.
 44          */
 45         notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
 46         notifier_ret = notifier_to_errno(notifier_ret);
 47         if (notifier_ret)
 48                 goto out;
 49         /*
 50          * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
 51          * We just check MOVABLE pages.
 52          */
 53         if (!has_unmovable_pages(zone, page, arg.pages_found,
 54                                  skip_hwpoisoned_pages))
 55                 ret = 0;
 56 
 57         /*
 58          * immobile means "not-on-lru" pages. If immobile is larger than
 59          * removable-by-driver pages reported by notifier, we'll fail.
 60          */
 61 
 62 out:
 63         if (!ret) {
 64                 unsigned long nr_pages;
 65                 int migratetype = get_pageblock_migratetype(page);
 66 
 67                 set_pageblock_migratetype(page, MIGRATE_ISOLATE);
 68                 zone->nr_isolate_pageblock++;
 69                 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
 70 
 71                 __mod_zone_freepage_state(zone, -nr_pages, migratetype);
 72         }
 73 
 74         spin_unlock_irqrestore(&zone->lock, flags);
 75         if (!ret)
 76                 drain_all_pages(zone);
 77         return ret;
 78 }
 79 
 80 static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
 81 {
 82         struct zone *zone;
 83         unsigned long flags, nr_pages;
 84         bool isolated_page = false;
 85         unsigned int order;
 86         unsigned long page_idx, buddy_idx;
 87         struct page *buddy;
 88 
 89         zone = page_zone(page);
 90         spin_lock_irqsave(&zone->lock, flags);
 91         if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
 92                 goto out;
 93 
 94         /*
 95          * Because freepage with more than pageblock_order on isolated
 96          * pageblock is restricted to merge due to freepage counting problem,
 97          * it is possible that there is free buddy page.
 98          * move_freepages_block() doesn't care of merge so we need other
 99          * approach in order to merge them. Isolation and free will make
100          * these pages to be merged.
101          */
102         if (PageBuddy(page)) {
103                 order = page_order(page);
104                 if (order >= pageblock_order) {
105                         page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
106                         buddy_idx = __find_buddy_index(page_idx, order);
107                         buddy = page + (buddy_idx - page_idx);
108 
109                         if (pfn_valid_within(page_to_pfn(buddy)) &&
110                             !is_migrate_isolate_page(buddy)) {
111                                 __isolate_free_page(page, order);
112                                 isolated_page = true;
113                         }
114                 }
115         }
116 
117         /*
118          * If we isolate freepage with more than pageblock_order, there
119          * should be no freepage in the range, so we could avoid costly
120          * pageblock scanning for freepage moving.
121          */
122         if (!isolated_page) {
123                 nr_pages = move_freepages_block(zone, page, migratetype);
124                 __mod_zone_freepage_state(zone, nr_pages, migratetype);
125         }
126         set_pageblock_migratetype(page, migratetype);
127         zone->nr_isolate_pageblock--;
128 out:
129         spin_unlock_irqrestore(&zone->lock, flags);
130         if (isolated_page) {
131                 post_alloc_hook(page, order, __GFP_MOVABLE);
132                 __free_pages(page, order);
133         }
134 }
135 
136 static inline struct page *
137 __first_valid_page(unsigned long pfn, unsigned long nr_pages)
138 {
139         int i;
140         for (i = 0; i < nr_pages; i++)
141                 if (pfn_valid_within(pfn + i))
142                         break;
143         if (unlikely(i == nr_pages))
144                 return NULL;
145         return pfn_to_page(pfn + i);
146 }
147 
148 /*
149  * start_isolate_page_range() -- make page-allocation-type of range of pages
150  * to be MIGRATE_ISOLATE.
151  * @start_pfn: The lower PFN of the range to be isolated.
152  * @end_pfn: The upper PFN of the range to be isolated.
153  * @migratetype: migrate type to set in error recovery.
154  *
155  * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
156  * the range will never be allocated. Any free pages and pages freed in the
157  * future will not be allocated again.
158  *
159  * start_pfn/end_pfn must be aligned to pageblock_order.
160  * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
161  */
162 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
163                              unsigned migratetype, bool skip_hwpoisoned_pages)
164 {
165         unsigned long pfn;
166         unsigned long undo_pfn;
167         struct page *page;
168 
169         BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
170         BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
171 
172         for (pfn = start_pfn;
173              pfn < end_pfn;
174              pfn += pageblock_nr_pages) {
175                 page = __first_valid_page(pfn, pageblock_nr_pages);
176                 if (page &&
177                     set_migratetype_isolate(page, skip_hwpoisoned_pages)) {
178                         undo_pfn = pfn;
179                         goto undo;
180                 }
181         }
182         return 0;
183 undo:
184         for (pfn = start_pfn;
185              pfn < undo_pfn;
186              pfn += pageblock_nr_pages)
187                 unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
188 
189         return -EBUSY;
190 }
191 
192 /*
193  * Make isolated pages available again.
194  */
195 int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
196                             unsigned migratetype)
197 {
198         unsigned long pfn;
199         struct page *page;
200 
201         BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
202         BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
203 
204         for (pfn = start_pfn;
205              pfn < end_pfn;
206              pfn += pageblock_nr_pages) {
207                 page = __first_valid_page(pfn, pageblock_nr_pages);
208                 if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
209                         continue;
210                 unset_migratetype_isolate(page, migratetype);
211         }
212         return 0;
213 }
214 /*
215  * Test all pages in the range is free(means isolated) or not.
216  * all pages in [start_pfn...end_pfn) must be in the same zone.
217  * zone->lock must be held before call this.
218  *
219  * Returns the last tested pfn.
220  */
221 static unsigned long
222 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
223                                   bool skip_hwpoisoned_pages)
224 {
225         struct page *page;
226 
227         while (pfn < end_pfn) {
228                 if (!pfn_valid_within(pfn)) {
229                         pfn++;
230                         continue;
231                 }
232                 page = pfn_to_page(pfn);
233                 if (PageBuddy(page))
234                         /*
235                          * If the page is on a free list, it has to be on
236                          * the correct MIGRATE_ISOLATE freelist. There is no
237                          * simple way to verify that as VM_BUG_ON(), though.
238                          */
239                         pfn += 1 << page_order(page);
240                 else if (skip_hwpoisoned_pages && PageHWPoison(page))
241                         /* A HWPoisoned page cannot be also PageBuddy */
242                         pfn++;
243                 else
244                         break;
245         }
246 
247         return pfn;
248 }
249 
250 /* Caller should ensure that requested range is in a single zone */
251 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
252                         bool skip_hwpoisoned_pages)
253 {
254         unsigned long pfn, flags;
255         struct page *page;
256         struct zone *zone;
257 
258         /*
259          * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
260          * are not aligned to pageblock_nr_pages.
261          * Then we just check migratetype first.
262          */
263         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
264                 page = __first_valid_page(pfn, pageblock_nr_pages);
265                 if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
266                         break;
267         }
268         page = __first_valid_page(start_pfn, end_pfn - start_pfn);
269         if ((pfn < end_pfn) || !page)
270                 return -EBUSY;
271         /* Check all pages are free or marked as ISOLATED */
272         zone = page_zone(page);
273         spin_lock_irqsave(&zone->lock, flags);
274         pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
275                                                 skip_hwpoisoned_pages);
276         spin_unlock_irqrestore(&zone->lock, flags);
277 
278         trace_test_pages_isolated(start_pfn, end_pfn, pfn);
279 
280         return pfn < end_pfn ? -EBUSY : 0;
281 }
282 
283 struct page *alloc_migrate_target(struct page *page, unsigned long private,
284                                   int **resultp)
285 {
286         gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
287 
288         /*
289          * TODO: allocate a destination hugepage from a nearest neighbor node,
290          * accordance with memory policy of the user process if possible. For
291          * now as a simple work-around, we use the next node for destination.
292          */
293         if (PageHuge(page))
294                 return alloc_huge_page_node(page_hstate(compound_head(page)),
295                                             next_node_in(page_to_nid(page),
296                                                          node_online_map));
297 
298         if (PageHighMem(page))
299                 gfp_mask |= __GFP_HIGHMEM;
300 
301         return alloc_page(gfp_mask);
302 }
303 

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us