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 <linux/migrate.h>
  12 #include "internal.h"
  13
  14 #define CREATE_TRACE_POINTS
  15 #include <trace/events/page_isolation.h>
  16
  17 static int set_migratetype_isolate(struct page *page,
  18                                 bool skip_hwpoisoned_pages)
  19 {
  20         struct zone *zone;
  21         unsigned long flags, pfn;
  22         struct memory_isolate_notify arg;
  23         int notifier_ret;
  24         int ret = -EBUSY;
  25
  26         zone = page_zone(page);
  27
  28         spin_lock_irqsave(&zone->lock, flags);
  29
  30         pfn = page_to_pfn(page);
  31         arg.start_pfn = pfn;
  32         arg.nr_pages = pageblock_nr_pages;
  33         arg.pages_found = 0;
  34
  35         /*
  36          * It may be possible to isolate a pageblock even if the
  37          * migratetype is not MIGRATE_MOVABLE. The memory isolation
  38          * notifier chain is used by balloon drivers to return the
  39          * number of pages in a range that are held by the balloon
  40          * driver to shrink memory. If all the pages are accounted for
  41          * by balloons, are free, or on the LRU, isolation can continue.
  42          * Later, for example, when memory hotplug notifier runs, these
  43          * pages reported as "can be isolated" should be isolated(freed)
  44          * by the balloon driver through the memory notifier chain.
  45          */
  46         notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
  47         notifier_ret = notifier_to_errno(notifier_ret);
  48         if (notifier_ret)
  49                 goto out;
  50         /*
  51          * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
  52          * We just check MOVABLE pages.
  53          */
  54         if (!has_unmovable_pages(zone, page, arg.pages_found,
  55                                  skip_hwpoisoned_pages))
  56                 ret = 0;
  57
  58         /*
  59          * immobile means "not-on-lru" pages. If immobile is larger than
  60          * removable-by-driver pages reported by notifier, we'll fail.
  61          */
  62
  63 out:
  64         if (!ret) {
  65                 unsigned long nr_pages;
  66                 int migratetype = get_pageblock_migratetype(page);
  67
  68                 set_pageblock_migratetype(page, MIGRATE_ISOLATE);
  69                 zone->nr_isolate_pageblock++;
  70                 nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE,
  71                                                                         NULL);
  72
  73                 __mod_zone_freepage_state(zone, -nr_pages, migratetype);
  74         }
  75
  76         spin_unlock_irqrestore(&zone->lock, flags);
  77         if (!ret)
  78                 drain_all_pages(zone);
  79         return ret;
  80 }
  81
  82 static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
  83 {
  84         struct zone *zone;
  85         unsigned long flags, nr_pages;
  86         bool isolated_page = false;
  87         unsigned int order;
  88         unsigned long pfn, buddy_pfn;
  89         struct page *buddy;
  90
  91         zone = page_zone(page);
  92         spin_lock_irqsave(&zone->lock, flags);
  93         if (!is_migrate_isolate_page(page))
  94                 goto out;
  95
  96         /*
  97          * Because freepage with more than pageblock_order on isolated
  98          * pageblock is restricted to merge due to freepage counting problem,
  99          * it is possible that there is free buddy page.
 100          * move_freepages_block() doesn't care of merge so we need other
 101          * approach in order to merge them. Isolation and free will make
 102          * these pages to be merged.
 103          */
 104         if (PageBuddy(page)) {
 105                 order = page_order(page);
 106                 if (order >= pageblock_order) {
 107                         pfn = page_to_pfn(page);
 108                         buddy_pfn = __find_buddy_pfn(pfn, order);
 109                         buddy = page + (buddy_pfn - pfn);
 110
 111                         if (pfn_valid_within(buddy_pfn) &&
 112                             !is_migrate_isolate_page(buddy)) {
 113                                 __isolate_free_page(page, order);
 114                                 isolated_page = true;
 115                         }
 116                 }
 117         }
 118
 119         /*
 120          * If we isolate freepage with more than pageblock_order, there
 121          * should be no freepage in the range, so we could avoid costly
 122          * pageblock scanning for freepage moving.
 123          */
 124         if (!isolated_page) {
 125                 nr_pages = move_freepages_block(zone, page, migratetype, NULL);
 126                 __mod_zone_freepage_state(zone, nr_pages, migratetype);
 127         }
 128         set_pageblock_migratetype(page, migratetype);
 129         zone->nr_isolate_pageblock--;
 130 out:
 131         spin_unlock_irqrestore(&zone->lock, flags);
 132         if (isolated_page) {
 133                 post_alloc_hook(page, order, __GFP_MOVABLE);
 134                 __free_pages(page, order);
 135         }
 136 }
 137
 138 static inline struct page *
 139 __first_valid_page(unsigned long pfn, unsigned long nr_pages)
 140 {
 141         int i;
 142
 143         for (i = 0; i < nr_pages; i++) {
 144                 struct page *page;
 145
 146                 if (!pfn_valid_within(pfn + i))
 147                         continue;
 148                 page = pfn_to_online_page(pfn + i);
 149                 if (!page)
 150                         continue;
 151                 return page;
 152         }
 153         return NULL;
 154 }
 155
 156 /*
 157  * start_isolate_page_range() -- make page-allocation-type of range of pages
 158  * to be MIGRATE_ISOLATE.
 159  * @start_pfn: The lower PFN of the range to be isolated.
 160  * @end_pfn: The upper PFN of the range to be isolated.
 161  * @migratetype: migrate type to set in error recovery.
 162  *
 163  * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
 164  * the range will never be allocated. Any free pages and pages freed in the
 165  * future will not be allocated again.
 166  *
 167  * start_pfn/end_pfn must be aligned to pageblock_order.
 168  * Returns 0 on success and -EBUSY if any part of range cannot be isolated.
 169  */
 170 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 171                              unsigned migratetype, bool skip_hwpoisoned_pages)
 172 {
 173         unsigned long pfn;
 174         unsigned long undo_pfn;
 175         struct page *page;
 176
 177         BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
 178         BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
 179
 180         for (pfn = start_pfn;
 181              pfn < end_pfn;
 182              pfn += pageblock_nr_pages) {
 183                 page = __first_valid_page(pfn, pageblock_nr_pages);
 184                 if (page &&
 185                     set_migratetype_isolate(page, skip_hwpoisoned_pages)) {
 186                         undo_pfn = pfn;
 187                         goto undo;
 188                 }
 189         }
 190         return 0;
 191 undo:
 192         for (pfn = start_pfn;
 193              pfn < undo_pfn;
 194              pfn += pageblock_nr_pages) {
 195                 struct page *page = pfn_to_online_page(pfn);
 196                 if (!page)
 197                         continue;
 198                 unset_migratetype_isolate(page, migratetype);
 199         }
 200
 201         return -EBUSY;
 202 }
 203
 204 /*
 205  * Make isolated pages available again.
 206  */
 207 int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 208                             unsigned migratetype)
 209 {
 210         unsigned long pfn;
 211         struct page *page;
 212
 213         BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
 214         BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));
 215
 216         for (pfn = start_pfn;
 217              pfn < end_pfn;
 218              pfn += pageblock_nr_pages) {
 219                 page = __first_valid_page(pfn, pageblock_nr_pages);
 220                 if (!page || !is_migrate_isolate_page(page))
 221                         continue;
 222                 unset_migratetype_isolate(page, migratetype);
 223         }
 224         return 0;
 225 }
 226 /*
 227  * Test all pages in the range is free(means isolated) or not.
 228  * all pages in [start_pfn...end_pfn) must be in the same zone.
 229  * zone->lock must be held before call this.
 230  *
 231  * Returns the last tested pfn.
 232  */
 233 static unsigned long
 234 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
 235                                   bool skip_hwpoisoned_pages)
 236 {
 237         struct page *page;
 238
 239         while (pfn < end_pfn) {
 240                 if (!pfn_valid_within(pfn)) {
 241                         pfn++;
 242                         continue;
 243                 }
 244                 page = pfn_to_page(pfn);
 245                 if (PageBuddy(page))
 246                         /*
 247                          * If the page is on a free list, it has to be on
 248                          * the correct MIGRATE_ISOLATE freelist. There is no
 249                          * simple way to verify that as VM_BUG_ON(), though.
 250                          */
 251                         pfn += 1 << page_order(page);
 252                 else if (skip_hwpoisoned_pages && PageHWPoison(page))
 253                         /* A HWPoisoned page cannot be also PageBuddy */
 254                         pfn++;
 255                 else
 256                         break;
 257         }
 258
 259         return pfn;
 260 }
 261
 262 /* Caller should ensure that requested range is in a single zone */
 263 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
 264                         bool skip_hwpoisoned_pages)
 265 {
 266         unsigned long pfn, flags;
 267         struct page *page;
 268         struct zone *zone;
 269
 270         /*
 271          * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
 272          * are not aligned to pageblock_nr_pages.
 273          * Then we just check migratetype first.
 274          */
 275         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 276                 page = __first_valid_page(pfn, pageblock_nr_pages);
 277                 if (page && !is_migrate_isolate_page(page))
 278                         break;
 279         }
 280         page = __first_valid_page(start_pfn, end_pfn - start_pfn);
 281         if ((pfn < end_pfn) || !page)
 282                 return -EBUSY;
 283         /* Check all pages are free or marked as ISOLATED */
 284         zone = page_zone(page);
 285         spin_lock_irqsave(&zone->lock, flags);
 286         pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
 287                                                 skip_hwpoisoned_pages);
 288         spin_unlock_irqrestore(&zone->lock, flags);
 289
 290         trace_test_pages_isolated(start_pfn, end_pfn, pfn);
 291
 292         return pfn < end_pfn ? -EBUSY : 0;
 293 }
 294
 295 struct page *alloc_migrate_target(struct page *page, unsigned long private,
 296                                   int **resultp)
 297 {
 298         return new_page_nodemask(page, numa_node_id(), &node_states[N_MEMORY]);
 299 }