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