dm ioctl: use kmalloc if possible
[linux-3.10.git] / mm / memory_hotplug.c
1 /*
2  *  linux/mm/memory_hotplug.c
3  *
4  *  Copyright (C)
5  */
6
7 #include <linux/stddef.h>
8 #include <linux/mm.h>
9 #include <linux/swap.h>
10 #include <linux/interrupt.h>
11 #include <linux/pagemap.h>
12 #include <linux/bootmem.h>
13 #include <linux/compiler.h>
14 #include <linux/export.h>
15 #include <linux/pagevec.h>
16 #include <linux/writeback.h>
17 #include <linux/slab.h>
18 #include <linux/sysctl.h>
19 #include <linux/cpu.h>
20 #include <linux/memory.h>
21 #include <linux/memory_hotplug.h>
22 #include <linux/highmem.h>
23 #include <linux/vmalloc.h>
24 #include <linux/ioport.h>
25 #include <linux/delay.h>
26 #include <linux/migrate.h>
27 #include <linux/page-isolation.h>
28 #include <linux/pfn.h>
29 #include <linux/suspend.h>
30 #include <linux/mm_inline.h>
31 #include <linux/firmware-map.h>
32
33 #include <asm/tlbflush.h>
34
35 #include "internal.h"
36
37 /*
38  * online_page_callback contains pointer to current page onlining function.
39  * Initially it is generic_online_page(). If it is required it could be
40  * changed by calling set_online_page_callback() for callback registration
41  * and restore_online_page_callback() for generic callback restore.
42  */
43
44 static void generic_online_page(struct page *page);
45
46 static online_page_callback_t online_page_callback = generic_online_page;
47
48 DEFINE_MUTEX(mem_hotplug_mutex);
49
50 void lock_memory_hotplug(void)
51 {
52         mutex_lock(&mem_hotplug_mutex);
53
54         /* for exclusive hibernation if CONFIG_HIBERNATION=y */
55         lock_system_sleep();
56 }
57
58 void unlock_memory_hotplug(void)
59 {
60         unlock_system_sleep();
61         mutex_unlock(&mem_hotplug_mutex);
62 }
63
64
65 /* add this memory to iomem resource */
66 static struct resource *register_memory_resource(u64 start, u64 size)
67 {
68         struct resource *res;
69         res = kzalloc(sizeof(struct resource), GFP_KERNEL);
70         BUG_ON(!res);
71
72         res->name = "System RAM";
73         res->start = start;
74         res->end = start + size - 1;
75         res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
76         if (request_resource(&iomem_resource, res) < 0) {
77                 printk("System RAM resource %pR cannot be added\n", res);
78                 kfree(res);
79                 res = NULL;
80         }
81         return res;
82 }
83
84 static void release_memory_resource(struct resource *res)
85 {
86         if (!res)
87                 return;
88         release_resource(res);
89         kfree(res);
90         return;
91 }
92
93 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
94 #ifndef CONFIG_SPARSEMEM_VMEMMAP
95 static void get_page_bootmem(unsigned long info,  struct page *page,
96                              unsigned long type)
97 {
98         page->lru.next = (struct list_head *) type;
99         SetPagePrivate(page);
100         set_page_private(page, info);
101         atomic_inc(&page->_count);
102 }
103
104 /* reference to __meminit __free_pages_bootmem is valid
105  * so use __ref to tell modpost not to generate a warning */
106 void __ref put_page_bootmem(struct page *page)
107 {
108         unsigned long type;
109
110         type = (unsigned long) page->lru.next;
111         BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
112                type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
113
114         if (atomic_dec_return(&page->_count) == 1) {
115                 ClearPagePrivate(page);
116                 set_page_private(page, 0);
117                 INIT_LIST_HEAD(&page->lru);
118                 __free_pages_bootmem(page, 0);
119         }
120
121 }
122
123 static void register_page_bootmem_info_section(unsigned long start_pfn)
124 {
125         unsigned long *usemap, mapsize, section_nr, i;
126         struct mem_section *ms;
127         struct page *page, *memmap;
128
129         section_nr = pfn_to_section_nr(start_pfn);
130         ms = __nr_to_section(section_nr);
131
132         /* Get section's memmap address */
133         memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
134
135         /*
136          * Get page for the memmap's phys address
137          * XXX: need more consideration for sparse_vmemmap...
138          */
139         page = virt_to_page(memmap);
140         mapsize = sizeof(struct page) * PAGES_PER_SECTION;
141         mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT;
142
143         /* remember memmap's page */
144         for (i = 0; i < mapsize; i++, page++)
145                 get_page_bootmem(section_nr, page, SECTION_INFO);
146
147         usemap = __nr_to_section(section_nr)->pageblock_flags;
148         page = virt_to_page(usemap);
149
150         mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
151
152         for (i = 0; i < mapsize; i++, page++)
153                 get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
154
155 }
156
157 void register_page_bootmem_info_node(struct pglist_data *pgdat)
158 {
159         unsigned long i, pfn, end_pfn, nr_pages;
160         int node = pgdat->node_id;
161         struct page *page;
162         struct zone *zone;
163
164         nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT;
165         page = virt_to_page(pgdat);
166
167         for (i = 0; i < nr_pages; i++, page++)
168                 get_page_bootmem(node, page, NODE_INFO);
169
170         zone = &pgdat->node_zones[0];
171         for (; zone < pgdat->node_zones + MAX_NR_ZONES - 1; zone++) {
172                 if (zone->wait_table) {
173                         nr_pages = zone->wait_table_hash_nr_entries
174                                 * sizeof(wait_queue_head_t);
175                         nr_pages = PAGE_ALIGN(nr_pages) >> PAGE_SHIFT;
176                         page = virt_to_page(zone->wait_table);
177
178                         for (i = 0; i < nr_pages; i++, page++)
179                                 get_page_bootmem(node, page, NODE_INFO);
180                 }
181         }
182
183         pfn = pgdat->node_start_pfn;
184         end_pfn = pfn + pgdat->node_spanned_pages;
185
186         /* register_section info */
187         for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
188                 /*
189                  * Some platforms can assign the same pfn to multiple nodes - on
190                  * node0 as well as nodeN.  To avoid registering a pfn against
191                  * multiple nodes we check that this pfn does not already
192                  * reside in some other node.
193                  */
194                 if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node))
195                         register_page_bootmem_info_section(pfn);
196         }
197 }
198 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
199
200 static void grow_zone_span(struct zone *zone, unsigned long start_pfn,
201                            unsigned long end_pfn)
202 {
203         unsigned long old_zone_end_pfn;
204
205         zone_span_writelock(zone);
206
207         old_zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
208         if (start_pfn < zone->zone_start_pfn)
209                 zone->zone_start_pfn = start_pfn;
210
211         zone->spanned_pages = max(old_zone_end_pfn, end_pfn) -
212                                 zone->zone_start_pfn;
213
214         zone_span_writeunlock(zone);
215 }
216
217 static void grow_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn,
218                             unsigned long end_pfn)
219 {
220         unsigned long old_pgdat_end_pfn =
221                 pgdat->node_start_pfn + pgdat->node_spanned_pages;
222
223         if (start_pfn < pgdat->node_start_pfn)
224                 pgdat->node_start_pfn = start_pfn;
225
226         pgdat->node_spanned_pages = max(old_pgdat_end_pfn, end_pfn) -
227                                         pgdat->node_start_pfn;
228 }
229
230 static int __meminit __add_zone(struct zone *zone, unsigned long phys_start_pfn)
231 {
232         struct pglist_data *pgdat = zone->zone_pgdat;
233         int nr_pages = PAGES_PER_SECTION;
234         int nid = pgdat->node_id;
235         int zone_type;
236         unsigned long flags;
237
238         zone_type = zone - pgdat->node_zones;
239         if (!zone->wait_table) {
240                 int ret;
241
242                 ret = init_currently_empty_zone(zone, phys_start_pfn,
243                                                 nr_pages, MEMMAP_HOTPLUG);
244                 if (ret)
245                         return ret;
246         }
247         pgdat_resize_lock(zone->zone_pgdat, &flags);
248         grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
249         grow_pgdat_span(zone->zone_pgdat, phys_start_pfn,
250                         phys_start_pfn + nr_pages);
251         pgdat_resize_unlock(zone->zone_pgdat, &flags);
252         memmap_init_zone(nr_pages, nid, zone_type,
253                          phys_start_pfn, MEMMAP_HOTPLUG);
254         return 0;
255 }
256
257 static int __meminit __add_section(int nid, struct zone *zone,
258                                         unsigned long phys_start_pfn)
259 {
260         int nr_pages = PAGES_PER_SECTION;
261         int ret;
262
263         if (pfn_valid(phys_start_pfn))
264                 return -EEXIST;
265
266         ret = sparse_add_one_section(zone, phys_start_pfn, nr_pages);
267
268         if (ret < 0)
269                 return ret;
270
271         ret = __add_zone(zone, phys_start_pfn);
272
273         if (ret < 0)
274                 return ret;
275
276         return register_new_memory(nid, __pfn_to_section(phys_start_pfn));
277 }
278
279 #ifdef CONFIG_SPARSEMEM_VMEMMAP
280 static int __remove_section(struct zone *zone, struct mem_section *ms)
281 {
282         /*
283          * XXX: Freeing memmap with vmemmap is not implement yet.
284          *      This should be removed later.
285          */
286         return -EBUSY;
287 }
288 #else
289 static int __remove_section(struct zone *zone, struct mem_section *ms)
290 {
291         unsigned long flags;
292         struct pglist_data *pgdat = zone->zone_pgdat;
293         int ret = -EINVAL;
294
295         if (!valid_section(ms))
296                 return ret;
297
298         ret = unregister_memory_section(ms);
299         if (ret)
300                 return ret;
301
302         pgdat_resize_lock(pgdat, &flags);
303         sparse_remove_one_section(zone, ms);
304         pgdat_resize_unlock(pgdat, &flags);
305         return 0;
306 }
307 #endif
308
309 /*
310  * Reasonably generic function for adding memory.  It is
311  * expected that archs that support memory hotplug will
312  * call this function after deciding the zone to which to
313  * add the new pages.
314  */
315 int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
316                         unsigned long nr_pages)
317 {
318         unsigned long i;
319         int err = 0;
320         int start_sec, end_sec;
321         /* during initialize mem_map, align hot-added range to section */
322         start_sec = pfn_to_section_nr(phys_start_pfn);
323         end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
324
325         for (i = start_sec; i <= end_sec; i++) {
326                 err = __add_section(nid, zone, i << PFN_SECTION_SHIFT);
327
328                 /*
329                  * EEXIST is finally dealt with by ioresource collision
330                  * check. see add_memory() => register_memory_resource()
331                  * Warning will be printed if there is collision.
332                  */
333                 if (err && (err != -EEXIST))
334                         break;
335                 err = 0;
336         }
337
338         return err;
339 }
340 EXPORT_SYMBOL_GPL(__add_pages);
341
342 /**
343  * __remove_pages() - remove sections of pages from a zone
344  * @zone: zone from which pages need to be removed
345  * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
346  * @nr_pages: number of pages to remove (must be multiple of section size)
347  *
348  * Generic helper function to remove section mappings and sysfs entries
349  * for the section of the memory we are removing. Caller needs to make
350  * sure that pages are marked reserved and zones are adjust properly by
351  * calling offline_pages().
352  */
353 int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
354                  unsigned long nr_pages)
355 {
356         unsigned long i, ret = 0;
357         int sections_to_remove;
358
359         /*
360          * We can only remove entire sections
361          */
362         BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
363         BUG_ON(nr_pages % PAGES_PER_SECTION);
364
365         release_mem_region(phys_start_pfn << PAGE_SHIFT, nr_pages * PAGE_SIZE);
366
367         sections_to_remove = nr_pages / PAGES_PER_SECTION;
368         for (i = 0; i < sections_to_remove; i++) {
369                 unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
370                 ret = __remove_section(zone, __pfn_to_section(pfn));
371                 if (ret)
372                         break;
373         }
374         return ret;
375 }
376 EXPORT_SYMBOL_GPL(__remove_pages);
377
378 int set_online_page_callback(online_page_callback_t callback)
379 {
380         int rc = -EINVAL;
381
382         lock_memory_hotplug();
383
384         if (online_page_callback == generic_online_page) {
385                 online_page_callback = callback;
386                 rc = 0;
387         }
388
389         unlock_memory_hotplug();
390
391         return rc;
392 }
393 EXPORT_SYMBOL_GPL(set_online_page_callback);
394
395 int restore_online_page_callback(online_page_callback_t callback)
396 {
397         int rc = -EINVAL;
398
399         lock_memory_hotplug();
400
401         if (online_page_callback == callback) {
402                 online_page_callback = generic_online_page;
403                 rc = 0;
404         }
405
406         unlock_memory_hotplug();
407
408         return rc;
409 }
410 EXPORT_SYMBOL_GPL(restore_online_page_callback);
411
412 void __online_page_set_limits(struct page *page)
413 {
414         unsigned long pfn = page_to_pfn(page);
415
416         if (pfn >= num_physpages)
417                 num_physpages = pfn + 1;
418 }
419 EXPORT_SYMBOL_GPL(__online_page_set_limits);
420
421 void __online_page_increment_counters(struct page *page)
422 {
423         totalram_pages++;
424
425 #ifdef CONFIG_HIGHMEM
426         if (PageHighMem(page))
427                 totalhigh_pages++;
428 #endif
429 }
430 EXPORT_SYMBOL_GPL(__online_page_increment_counters);
431
432 void __online_page_free(struct page *page)
433 {
434         ClearPageReserved(page);
435         init_page_count(page);
436         __free_page(page);
437 }
438 EXPORT_SYMBOL_GPL(__online_page_free);
439
440 static void generic_online_page(struct page *page)
441 {
442         __online_page_set_limits(page);
443         __online_page_increment_counters(page);
444         __online_page_free(page);
445 }
446
447 static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
448                         void *arg)
449 {
450         unsigned long i;
451         unsigned long onlined_pages = *(unsigned long *)arg;
452         struct page *page;
453         if (PageReserved(pfn_to_page(start_pfn)))
454                 for (i = 0; i < nr_pages; i++) {
455                         page = pfn_to_page(start_pfn + i);
456                         (*online_page_callback)(page);
457                         onlined_pages++;
458                 }
459         *(unsigned long *)arg = onlined_pages;
460         return 0;
461 }
462
463
464 int __ref online_pages(unsigned long pfn, unsigned long nr_pages)
465 {
466         unsigned long onlined_pages = 0;
467         struct zone *zone;
468         int need_zonelists_rebuild = 0;
469         int nid;
470         int ret;
471         struct memory_notify arg;
472
473         lock_memory_hotplug();
474         arg.start_pfn = pfn;
475         arg.nr_pages = nr_pages;
476         arg.status_change_nid = -1;
477
478         nid = page_to_nid(pfn_to_page(pfn));
479         if (node_present_pages(nid) == 0)
480                 arg.status_change_nid = nid;
481
482         ret = memory_notify(MEM_GOING_ONLINE, &arg);
483         ret = notifier_to_errno(ret);
484         if (ret) {
485                 memory_notify(MEM_CANCEL_ONLINE, &arg);
486                 unlock_memory_hotplug();
487                 return ret;
488         }
489         /*
490          * This doesn't need a lock to do pfn_to_page().
491          * The section can't be removed here because of the
492          * memory_block->state_mutex.
493          */
494         zone = page_zone(pfn_to_page(pfn));
495         /*
496          * If this zone is not populated, then it is not in zonelist.
497          * This means the page allocator ignores this zone.
498          * So, zonelist must be updated after online.
499          */
500         mutex_lock(&zonelists_mutex);
501         if (!populated_zone(zone))
502                 need_zonelists_rebuild = 1;
503
504         ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
505                 online_pages_range);
506         if (ret) {
507                 mutex_unlock(&zonelists_mutex);
508                 printk(KERN_DEBUG "online_pages [mem %#010llx-%#010llx] failed\n",
509                        (unsigned long long) pfn << PAGE_SHIFT,
510                        (((unsigned long long) pfn + nr_pages)
511                             << PAGE_SHIFT) - 1);
512                 memory_notify(MEM_CANCEL_ONLINE, &arg);
513                 unlock_memory_hotplug();
514                 return ret;
515         }
516
517         zone->present_pages += onlined_pages;
518         zone->zone_pgdat->node_present_pages += onlined_pages;
519         if (onlined_pages) {
520                 node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
521                 if (need_zonelists_rebuild)
522                         build_all_zonelists(NULL, zone);
523                 else
524                         zone_pcp_update(zone);
525         }
526
527         mutex_unlock(&zonelists_mutex);
528
529         init_per_zone_wmark_min();
530
531         if (onlined_pages)
532                 kswapd_run(zone_to_nid(zone));
533
534         vm_total_pages = nr_free_pagecache_pages();
535
536         writeback_set_ratelimit();
537
538         if (onlined_pages)
539                 memory_notify(MEM_ONLINE, &arg);
540         unlock_memory_hotplug();
541
542         return 0;
543 }
544 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
545
546 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
547 static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
548 {
549         struct pglist_data *pgdat;
550         unsigned long zones_size[MAX_NR_ZONES] = {0};
551         unsigned long zholes_size[MAX_NR_ZONES] = {0};
552         unsigned long start_pfn = start >> PAGE_SHIFT;
553
554         pgdat = arch_alloc_nodedata(nid);
555         if (!pgdat)
556                 return NULL;
557
558         arch_refresh_nodedata(nid, pgdat);
559
560         /* we can use NODE_DATA(nid) from here */
561
562         /* init node's zones as empty zones, we don't have any present pages.*/
563         free_area_init_node(nid, zones_size, start_pfn, zholes_size);
564
565         /*
566          * The node we allocated has no zone fallback lists. For avoiding
567          * to access not-initialized zonelist, build here.
568          */
569         mutex_lock(&zonelists_mutex);
570         build_all_zonelists(pgdat, NULL);
571         mutex_unlock(&zonelists_mutex);
572
573         return pgdat;
574 }
575
576 static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
577 {
578         arch_refresh_nodedata(nid, NULL);
579         arch_free_nodedata(pgdat);
580         return;
581 }
582
583
584 /*
585  * called by cpu_up() to online a node without onlined memory.
586  */
587 int mem_online_node(int nid)
588 {
589         pg_data_t       *pgdat;
590         int     ret;
591
592         lock_memory_hotplug();
593         pgdat = hotadd_new_pgdat(nid, 0);
594         if (!pgdat) {
595                 ret = -ENOMEM;
596                 goto out;
597         }
598         node_set_online(nid);
599         ret = register_one_node(nid);
600         BUG_ON(ret);
601
602 out:
603         unlock_memory_hotplug();
604         return ret;
605 }
606
607 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
608 int __ref add_memory(int nid, u64 start, u64 size)
609 {
610         pg_data_t *pgdat = NULL;
611         int new_pgdat = 0;
612         struct resource *res;
613         int ret;
614
615         lock_memory_hotplug();
616
617         res = register_memory_resource(start, size);
618         ret = -EEXIST;
619         if (!res)
620                 goto out;
621
622         if (!node_online(nid)) {
623                 pgdat = hotadd_new_pgdat(nid, start);
624                 ret = -ENOMEM;
625                 if (!pgdat)
626                         goto error;
627                 new_pgdat = 1;
628         }
629
630         /* call arch's memory hotadd */
631         ret = arch_add_memory(nid, start, size);
632
633         if (ret < 0)
634                 goto error;
635
636         /* we online node here. we can't roll back from here. */
637         node_set_online(nid);
638
639         if (new_pgdat) {
640                 ret = register_one_node(nid);
641                 /*
642                  * If sysfs file of new node can't create, cpu on the node
643                  * can't be hot-added. There is no rollback way now.
644                  * So, check by BUG_ON() to catch it reluctantly..
645                  */
646                 BUG_ON(ret);
647         }
648
649         /* create new memmap entry */
650         firmware_map_add_hotplug(start, start + size, "System RAM");
651
652         goto out;
653
654 error:
655         /* rollback pgdat allocation and others */
656         if (new_pgdat)
657                 rollback_node_hotadd(nid, pgdat);
658         if (res)
659                 release_memory_resource(res);
660
661 out:
662         unlock_memory_hotplug();
663         return ret;
664 }
665 EXPORT_SYMBOL_GPL(add_memory);
666
667 #ifdef CONFIG_MEMORY_HOTREMOVE
668 /*
669  * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
670  * set and the size of the free page is given by page_order(). Using this,
671  * the function determines if the pageblock contains only free pages.
672  * Due to buddy contraints, a free page at least the size of a pageblock will
673  * be located at the start of the pageblock
674  */
675 static inline int pageblock_free(struct page *page)
676 {
677         return PageBuddy(page) && page_order(page) >= pageblock_order;
678 }
679
680 /* Return the start of the next active pageblock after a given page */
681 static struct page *next_active_pageblock(struct page *page)
682 {
683         /* Ensure the starting page is pageblock-aligned */
684         BUG_ON(page_to_pfn(page) & (pageblock_nr_pages - 1));
685
686         /* If the entire pageblock is free, move to the end of free page */
687         if (pageblock_free(page)) {
688                 int order;
689                 /* be careful. we don't have locks, page_order can be changed.*/
690                 order = page_order(page);
691                 if ((order < MAX_ORDER) && (order >= pageblock_order))
692                         return page + (1 << order);
693         }
694
695         return page + pageblock_nr_pages;
696 }
697
698 /* Checks if this range of memory is likely to be hot-removable. */
699 int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
700 {
701         struct page *page = pfn_to_page(start_pfn);
702         struct page *end_page = page + nr_pages;
703
704         /* Check the starting page of each pageblock within the range */
705         for (; page < end_page; page = next_active_pageblock(page)) {
706                 if (!is_pageblock_removable_nolock(page))
707                         return 0;
708                 cond_resched();
709         }
710
711         /* All pageblocks in the memory block are likely to be hot-removable */
712         return 1;
713 }
714
715 /*
716  * Confirm all pages in a range [start, end) is belongs to the same zone.
717  */
718 static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
719 {
720         unsigned long pfn;
721         struct zone *zone = NULL;
722         struct page *page;
723         int i;
724         for (pfn = start_pfn;
725              pfn < end_pfn;
726              pfn += MAX_ORDER_NR_PAGES) {
727                 i = 0;
728                 /* This is just a CONFIG_HOLES_IN_ZONE check.*/
729                 while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i))
730                         i++;
731                 if (i == MAX_ORDER_NR_PAGES)
732                         continue;
733                 page = pfn_to_page(pfn + i);
734                 if (zone && page_zone(page) != zone)
735                         return 0;
736                 zone = page_zone(page);
737         }
738         return 1;
739 }
740
741 /*
742  * Scanning pfn is much easier than scanning lru list.
743  * Scan pfn from start to end and Find LRU page.
744  */
745 static unsigned long scan_lru_pages(unsigned long start, unsigned long end)
746 {
747         unsigned long pfn;
748         struct page *page;
749         for (pfn = start; pfn < end; pfn++) {
750                 if (pfn_valid(pfn)) {
751                         page = pfn_to_page(pfn);
752                         if (PageLRU(page))
753                                 return pfn;
754                 }
755         }
756         return 0;
757 }
758
759 #define NR_OFFLINE_AT_ONCE_PAGES        (256)
760 static int
761 do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
762 {
763         unsigned long pfn;
764         struct page *page;
765         int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
766         int not_managed = 0;
767         int ret = 0;
768         LIST_HEAD(source);
769
770         for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
771                 if (!pfn_valid(pfn))
772                         continue;
773                 page = pfn_to_page(pfn);
774                 if (!get_page_unless_zero(page))
775                         continue;
776                 /*
777                  * We can skip free pages. And we can only deal with pages on
778                  * LRU.
779                  */
780                 ret = isolate_lru_page(page);
781                 if (!ret) { /* Success */
782                         put_page(page);
783                         list_add_tail(&page->lru, &source);
784                         move_pages--;
785                         inc_zone_page_state(page, NR_ISOLATED_ANON +
786                                             page_is_file_cache(page));
787
788                 } else {
789 #ifdef CONFIG_DEBUG_VM
790                         printk(KERN_ALERT "removing pfn %lx from LRU failed\n",
791                                pfn);
792                         dump_page(page);
793 #endif
794                         put_page(page);
795                         /* Because we don't have big zone->lock. we should
796                            check this again here. */
797                         if (page_count(page)) {
798                                 not_managed++;
799                                 ret = -EBUSY;
800                                 break;
801                         }
802                 }
803         }
804         if (!list_empty(&source)) {
805                 if (not_managed) {
806                         putback_lru_pages(&source);
807                         goto out;
808                 }
809
810                 /*
811                  * alloc_migrate_target should be improooooved!!
812                  * migrate_pages returns # of failed pages.
813                  */
814                 ret = migrate_pages(&source, alloc_migrate_target, 0,
815                                                         true, MIGRATE_SYNC);
816                 if (ret)
817                         putback_lru_pages(&source);
818         }
819 out:
820         return ret;
821 }
822
823 /*
824  * remove from free_area[] and mark all as Reserved.
825  */
826 static int
827 offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
828                         void *data)
829 {
830         __offline_isolated_pages(start, start + nr_pages);
831         return 0;
832 }
833
834 static void
835 offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
836 {
837         walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
838                                 offline_isolated_pages_cb);
839 }
840
841 /*
842  * Check all pages in range, recoreded as memory resource, are isolated.
843  */
844 static int
845 check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
846                         void *data)
847 {
848         int ret;
849         long offlined = *(long *)data;
850         ret = test_pages_isolated(start_pfn, start_pfn + nr_pages);
851         offlined = nr_pages;
852         if (!ret)
853                 *(long *)data += offlined;
854         return ret;
855 }
856
857 static long
858 check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
859 {
860         long offlined = 0;
861         int ret;
862
863         ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined,
864                         check_pages_isolated_cb);
865         if (ret < 0)
866                 offlined = (long)ret;
867         return offlined;
868 }
869
870 static int __ref __offline_pages(unsigned long start_pfn,
871                   unsigned long end_pfn, unsigned long timeout)
872 {
873         unsigned long pfn, nr_pages, expire;
874         long offlined_pages;
875         int ret, drain, retry_max, node;
876         struct zone *zone;
877         struct memory_notify arg;
878
879         BUG_ON(start_pfn >= end_pfn);
880         /* at least, alignment against pageblock is necessary */
881         if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
882                 return -EINVAL;
883         if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
884                 return -EINVAL;
885         /* This makes hotplug much easier...and readable.
886            we assume this for now. .*/
887         if (!test_pages_in_a_zone(start_pfn, end_pfn))
888                 return -EINVAL;
889
890         lock_memory_hotplug();
891
892         zone = page_zone(pfn_to_page(start_pfn));
893         node = zone_to_nid(zone);
894         nr_pages = end_pfn - start_pfn;
895
896         /* set above range as isolated */
897         ret = start_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
898         if (ret)
899                 goto out;
900
901         arg.start_pfn = start_pfn;
902         arg.nr_pages = nr_pages;
903         arg.status_change_nid = -1;
904         if (nr_pages >= node_present_pages(node))
905                 arg.status_change_nid = node;
906
907         ret = memory_notify(MEM_GOING_OFFLINE, &arg);
908         ret = notifier_to_errno(ret);
909         if (ret)
910                 goto failed_removal;
911
912         pfn = start_pfn;
913         expire = jiffies + timeout;
914         drain = 0;
915         retry_max = 5;
916 repeat:
917         /* start memory hot removal */
918         ret = -EAGAIN;
919         if (time_after(jiffies, expire))
920                 goto failed_removal;
921         ret = -EINTR;
922         if (signal_pending(current))
923                 goto failed_removal;
924         ret = 0;
925         if (drain) {
926                 lru_add_drain_all();
927                 cond_resched();
928                 drain_all_pages();
929         }
930
931         pfn = scan_lru_pages(start_pfn, end_pfn);
932         if (pfn) { /* We have page on LRU */
933                 ret = do_migrate_range(pfn, end_pfn);
934                 if (!ret) {
935                         drain = 1;
936                         goto repeat;
937                 } else {
938                         if (ret < 0)
939                                 if (--retry_max == 0)
940                                         goto failed_removal;
941                         yield();
942                         drain = 1;
943                         goto repeat;
944                 }
945         }
946         /* drain all zone's lru pagevec, this is asyncronous... */
947         lru_add_drain_all();
948         yield();
949         /* drain pcp pages , this is synchrouns. */
950         drain_all_pages();
951         /* check again */
952         offlined_pages = check_pages_isolated(start_pfn, end_pfn);
953         if (offlined_pages < 0) {
954                 ret = -EBUSY;
955                 goto failed_removal;
956         }
957         printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages);
958         /* Ok, all of our target is islaoted.
959            We cannot do rollback at this point. */
960         offline_isolated_pages(start_pfn, end_pfn);
961         /* reset pagetype flags and makes migrate type to be MOVABLE */
962         undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
963         /* removal success */
964         zone->present_pages -= offlined_pages;
965         zone->zone_pgdat->node_present_pages -= offlined_pages;
966         totalram_pages -= offlined_pages;
967
968         init_per_zone_wmark_min();
969
970         if (!populated_zone(zone)) {
971                 zone_pcp_reset(zone);
972                 mutex_lock(&zonelists_mutex);
973                 build_all_zonelists(NULL, NULL);
974                 mutex_unlock(&zonelists_mutex);
975         } else
976                 zone_pcp_update(zone);
977
978         if (!node_present_pages(node)) {
979                 node_clear_state(node, N_HIGH_MEMORY);
980                 kswapd_stop(node);
981         }
982
983         vm_total_pages = nr_free_pagecache_pages();
984         writeback_set_ratelimit();
985
986         memory_notify(MEM_OFFLINE, &arg);
987         unlock_memory_hotplug();
988         return 0;
989
990 failed_removal:
991         printk(KERN_INFO "memory offlining [mem %#010llx-%#010llx] failed\n",
992                (unsigned long long) start_pfn << PAGE_SHIFT,
993                ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
994         memory_notify(MEM_CANCEL_OFFLINE, &arg);
995         /* pushback to free area */
996         undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
997
998 out:
999         unlock_memory_hotplug();
1000         return ret;
1001 }
1002
1003 int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
1004 {
1005         return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
1006 }
1007
1008 int remove_memory(u64 start, u64 size)
1009 {
1010         struct memory_block *mem = NULL;
1011         struct mem_section *section;
1012         unsigned long start_pfn, end_pfn;
1013         unsigned long pfn, section_nr;
1014         int ret;
1015
1016         start_pfn = PFN_DOWN(start);
1017         end_pfn = start_pfn + PFN_DOWN(size);
1018
1019         for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
1020                 section_nr = pfn_to_section_nr(pfn);
1021                 if (!present_section_nr(section_nr))
1022                         continue;
1023
1024                 section = __nr_to_section(section_nr);
1025                 /* same memblock? */
1026                 if (mem)
1027                         if ((section_nr >= mem->start_section_nr) &&
1028                             (section_nr <= mem->end_section_nr))
1029                                 continue;
1030
1031                 mem = find_memory_block_hinted(section, mem);
1032                 if (!mem)
1033                         continue;
1034
1035                 ret = offline_memory_block(mem);
1036                 if (ret) {
1037                         kobject_put(&mem->dev.kobj);
1038                         return ret;
1039                 }
1040         }
1041
1042         if (mem)
1043                 kobject_put(&mem->dev.kobj);
1044
1045         return 0;
1046 }
1047 #else
1048 int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
1049 {
1050         return -EINVAL;
1051 }
1052 int remove_memory(u64 start, u64 size)
1053 {
1054         return -EINVAL;
1055 }
1056 #endif /* CONFIG_MEMORY_HOTREMOVE */
1057 EXPORT_SYMBOL_GPL(remove_memory);