memory-hotplug: don't calculate vm_total_pages twice when rebuilding zonelists in...
[linux-2.6.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/module.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/cpuset.h>
26 #include <linux/delay.h>
27 #include <linux/migrate.h>
28 #include <linux/page-isolation.h>
29
30 #include <asm/tlbflush.h>
31
32 #include "internal.h"
33
34 /* add this memory to iomem resource */
35 static struct resource *register_memory_resource(u64 start, u64 size)
36 {
37         struct resource *res;
38         res = kzalloc(sizeof(struct resource), GFP_KERNEL);
39         BUG_ON(!res);
40
41         res->name = "System RAM";
42         res->start = start;
43         res->end = start + size - 1;
44         res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
45         if (request_resource(&iomem_resource, res) < 0) {
46                 printk("System RAM resource %llx - %llx cannot be added\n",
47                 (unsigned long long)res->start, (unsigned long long)res->end);
48                 kfree(res);
49                 res = NULL;
50         }
51         return res;
52 }
53
54 static void release_memory_resource(struct resource *res)
55 {
56         if (!res)
57                 return;
58         release_resource(res);
59         kfree(res);
60         return;
61 }
62
63 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
64 #ifndef CONFIG_SPARSEMEM_VMEMMAP
65 static void get_page_bootmem(unsigned long info,  struct page *page, int type)
66 {
67         atomic_set(&page->_mapcount, type);
68         SetPagePrivate(page);
69         set_page_private(page, info);
70         atomic_inc(&page->_count);
71 }
72
73 void put_page_bootmem(struct page *page)
74 {
75         int type;
76
77         type = atomic_read(&page->_mapcount);
78         BUG_ON(type >= -1);
79
80         if (atomic_dec_return(&page->_count) == 1) {
81                 ClearPagePrivate(page);
82                 set_page_private(page, 0);
83                 reset_page_mapcount(page);
84                 __free_pages_bootmem(page, 0);
85         }
86
87 }
88
89 static void register_page_bootmem_info_section(unsigned long start_pfn)
90 {
91         unsigned long *usemap, mapsize, section_nr, i;
92         struct mem_section *ms;
93         struct page *page, *memmap;
94
95         if (!pfn_valid(start_pfn))
96                 return;
97
98         section_nr = pfn_to_section_nr(start_pfn);
99         ms = __nr_to_section(section_nr);
100
101         /* Get section's memmap address */
102         memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
103
104         /*
105          * Get page for the memmap's phys address
106          * XXX: need more consideration for sparse_vmemmap...
107          */
108         page = virt_to_page(memmap);
109         mapsize = sizeof(struct page) * PAGES_PER_SECTION;
110         mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT;
111
112         /* remember memmap's page */
113         for (i = 0; i < mapsize; i++, page++)
114                 get_page_bootmem(section_nr, page, SECTION_INFO);
115
116         usemap = __nr_to_section(section_nr)->pageblock_flags;
117         page = virt_to_page(usemap);
118
119         mapsize = PAGE_ALIGN(usemap_size()) >> PAGE_SHIFT;
120
121         for (i = 0; i < mapsize; i++, page++)
122                 get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
123
124 }
125
126 void register_page_bootmem_info_node(struct pglist_data *pgdat)
127 {
128         unsigned long i, pfn, end_pfn, nr_pages;
129         int node = pgdat->node_id;
130         struct page *page;
131         struct zone *zone;
132
133         nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT;
134         page = virt_to_page(pgdat);
135
136         for (i = 0; i < nr_pages; i++, page++)
137                 get_page_bootmem(node, page, NODE_INFO);
138
139         zone = &pgdat->node_zones[0];
140         for (; zone < pgdat->node_zones + MAX_NR_ZONES - 1; zone++) {
141                 if (zone->wait_table) {
142                         nr_pages = zone->wait_table_hash_nr_entries
143                                 * sizeof(wait_queue_head_t);
144                         nr_pages = PAGE_ALIGN(nr_pages) >> PAGE_SHIFT;
145                         page = virt_to_page(zone->wait_table);
146
147                         for (i = 0; i < nr_pages; i++, page++)
148                                 get_page_bootmem(node, page, NODE_INFO);
149                 }
150         }
151
152         pfn = pgdat->node_start_pfn;
153         end_pfn = pfn + pgdat->node_spanned_pages;
154
155         /* register_section info */
156         for (; pfn < end_pfn; pfn += PAGES_PER_SECTION)
157                 register_page_bootmem_info_section(pfn);
158
159 }
160 #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
161
162 static void grow_zone_span(struct zone *zone, unsigned long start_pfn,
163                            unsigned long end_pfn)
164 {
165         unsigned long old_zone_end_pfn;
166
167         zone_span_writelock(zone);
168
169         old_zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
170         if (start_pfn < zone->zone_start_pfn)
171                 zone->zone_start_pfn = start_pfn;
172
173         zone->spanned_pages = max(old_zone_end_pfn, end_pfn) -
174                                 zone->zone_start_pfn;
175
176         zone_span_writeunlock(zone);
177 }
178
179 static void grow_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn,
180                             unsigned long end_pfn)
181 {
182         unsigned long old_pgdat_end_pfn =
183                 pgdat->node_start_pfn + pgdat->node_spanned_pages;
184
185         if (start_pfn < pgdat->node_start_pfn)
186                 pgdat->node_start_pfn = start_pfn;
187
188         pgdat->node_spanned_pages = max(old_pgdat_end_pfn, end_pfn) -
189                                         pgdat->node_start_pfn;
190 }
191
192 static int __add_zone(struct zone *zone, unsigned long phys_start_pfn)
193 {
194         struct pglist_data *pgdat = zone->zone_pgdat;
195         int nr_pages = PAGES_PER_SECTION;
196         int nid = pgdat->node_id;
197         int zone_type;
198         unsigned long flags;
199
200         zone_type = zone - pgdat->node_zones;
201         if (!zone->wait_table) {
202                 int ret;
203
204                 ret = init_currently_empty_zone(zone, phys_start_pfn,
205                                                 nr_pages, MEMMAP_HOTPLUG);
206                 if (ret)
207                         return ret;
208         }
209         pgdat_resize_lock(zone->zone_pgdat, &flags);
210         grow_zone_span(zone, phys_start_pfn, phys_start_pfn + nr_pages);
211         grow_pgdat_span(zone->zone_pgdat, phys_start_pfn,
212                         phys_start_pfn + nr_pages);
213         pgdat_resize_unlock(zone->zone_pgdat, &flags);
214         memmap_init_zone(nr_pages, nid, zone_type,
215                          phys_start_pfn, MEMMAP_HOTPLUG);
216         return 0;
217 }
218
219 static int __add_section(struct zone *zone, unsigned long phys_start_pfn)
220 {
221         int nr_pages = PAGES_PER_SECTION;
222         int ret;
223
224         if (pfn_valid(phys_start_pfn))
225                 return -EEXIST;
226
227         ret = sparse_add_one_section(zone, phys_start_pfn, nr_pages);
228
229         if (ret < 0)
230                 return ret;
231
232         ret = __add_zone(zone, phys_start_pfn);
233
234         if (ret < 0)
235                 return ret;
236
237         return register_new_memory(__pfn_to_section(phys_start_pfn));
238 }
239
240 #ifdef CONFIG_SPARSEMEM_VMEMMAP
241 static int __remove_section(struct zone *zone, struct mem_section *ms)
242 {
243         /*
244          * XXX: Freeing memmap with vmemmap is not implement yet.
245          *      This should be removed later.
246          */
247         return -EBUSY;
248 }
249 #else
250 static int __remove_section(struct zone *zone, struct mem_section *ms)
251 {
252         unsigned long flags;
253         struct pglist_data *pgdat = zone->zone_pgdat;
254         int ret = -EINVAL;
255
256         if (!valid_section(ms))
257                 return ret;
258
259         ret = unregister_memory_section(ms);
260         if (ret)
261                 return ret;
262
263         pgdat_resize_lock(pgdat, &flags);
264         sparse_remove_one_section(zone, ms);
265         pgdat_resize_unlock(pgdat, &flags);
266         return 0;
267 }
268 #endif
269
270 /*
271  * Reasonably generic function for adding memory.  It is
272  * expected that archs that support memory hotplug will
273  * call this function after deciding the zone to which to
274  * add the new pages.
275  */
276 int __add_pages(struct zone *zone, unsigned long phys_start_pfn,
277                  unsigned long nr_pages)
278 {
279         unsigned long i;
280         int err = 0;
281         int start_sec, end_sec;
282         /* during initialize mem_map, align hot-added range to section */
283         start_sec = pfn_to_section_nr(phys_start_pfn);
284         end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
285
286         for (i = start_sec; i <= end_sec; i++) {
287                 err = __add_section(zone, i << PFN_SECTION_SHIFT);
288
289                 /*
290                  * EEXIST is finally dealt with by ioresource collision
291                  * check. see add_memory() => register_memory_resource()
292                  * Warning will be printed if there is collision.
293                  */
294                 if (err && (err != -EEXIST))
295                         break;
296                 err = 0;
297         }
298
299         return err;
300 }
301 EXPORT_SYMBOL_GPL(__add_pages);
302
303 /**
304  * __remove_pages() - remove sections of pages from a zone
305  * @zone: zone from which pages need to be removed
306  * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
307  * @nr_pages: number of pages to remove (must be multiple of section size)
308  *
309  * Generic helper function to remove section mappings and sysfs entries
310  * for the section of the memory we are removing. Caller needs to make
311  * sure that pages are marked reserved and zones are adjust properly by
312  * calling offline_pages().
313  */
314 int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
315                  unsigned long nr_pages)
316 {
317         unsigned long i, ret = 0;
318         int sections_to_remove;
319
320         /*
321          * We can only remove entire sections
322          */
323         BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
324         BUG_ON(nr_pages % PAGES_PER_SECTION);
325
326         release_mem_region(phys_start_pfn << PAGE_SHIFT, nr_pages * PAGE_SIZE);
327
328         sections_to_remove = nr_pages / PAGES_PER_SECTION;
329         for (i = 0; i < sections_to_remove; i++) {
330                 unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
331                 ret = __remove_section(zone, __pfn_to_section(pfn));
332                 if (ret)
333                         break;
334         }
335         return ret;
336 }
337 EXPORT_SYMBOL_GPL(__remove_pages);
338
339 void online_page(struct page *page)
340 {
341         totalram_pages++;
342         num_physpages++;
343
344 #ifdef CONFIG_HIGHMEM
345         if (PageHighMem(page))
346                 totalhigh_pages++;
347 #endif
348
349 #ifdef CONFIG_FLATMEM
350         max_mapnr = max(page_to_pfn(page), max_mapnr);
351 #endif
352
353         ClearPageReserved(page);
354         init_page_count(page);
355         __free_page(page);
356 }
357
358 static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
359                         void *arg)
360 {
361         unsigned long i;
362         unsigned long onlined_pages = *(unsigned long *)arg;
363         struct page *page;
364         if (PageReserved(pfn_to_page(start_pfn)))
365                 for (i = 0; i < nr_pages; i++) {
366                         page = pfn_to_page(start_pfn + i);
367                         online_page(page);
368                         onlined_pages++;
369                 }
370         *(unsigned long *)arg = onlined_pages;
371         return 0;
372 }
373
374
375 int online_pages(unsigned long pfn, unsigned long nr_pages)
376 {
377         unsigned long onlined_pages = 0;
378         struct zone *zone;
379         int need_zonelists_rebuild = 0;
380         int nid;
381         int ret;
382         struct memory_notify arg;
383
384         arg.start_pfn = pfn;
385         arg.nr_pages = nr_pages;
386         arg.status_change_nid = -1;
387
388         nid = page_to_nid(pfn_to_page(pfn));
389         if (node_present_pages(nid) == 0)
390                 arg.status_change_nid = nid;
391
392         ret = memory_notify(MEM_GOING_ONLINE, &arg);
393         ret = notifier_to_errno(ret);
394         if (ret) {
395                 memory_notify(MEM_CANCEL_ONLINE, &arg);
396                 return ret;
397         }
398         /*
399          * This doesn't need a lock to do pfn_to_page().
400          * The section can't be removed here because of the
401          * memory_block->state_mutex.
402          */
403         zone = page_zone(pfn_to_page(pfn));
404         /*
405          * If this zone is not populated, then it is not in zonelist.
406          * This means the page allocator ignores this zone.
407          * So, zonelist must be updated after online.
408          */
409         if (!populated_zone(zone))
410                 need_zonelists_rebuild = 1;
411
412         ret = walk_memory_resource(pfn, nr_pages, &onlined_pages,
413                 online_pages_range);
414         if (ret) {
415                 printk(KERN_DEBUG "online_pages %lx at %lx failed\n",
416                         nr_pages, pfn);
417                 memory_notify(MEM_CANCEL_ONLINE, &arg);
418                 return ret;
419         }
420
421         zone->present_pages += onlined_pages;
422         zone->zone_pgdat->node_present_pages += onlined_pages;
423
424         setup_per_zone_pages_min();
425         if (onlined_pages) {
426                 kswapd_run(zone_to_nid(zone));
427                 node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
428         }
429
430         if (need_zonelists_rebuild)
431                 build_all_zonelists();
432         else
433                 vm_total_pages = nr_free_pagecache_pages();
434
435         writeback_set_ratelimit();
436
437         if (onlined_pages)
438                 memory_notify(MEM_ONLINE, &arg);
439
440         return 0;
441 }
442 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
443
444 static pg_data_t *hotadd_new_pgdat(int nid, u64 start)
445 {
446         struct pglist_data *pgdat;
447         unsigned long zones_size[MAX_NR_ZONES] = {0};
448         unsigned long zholes_size[MAX_NR_ZONES] = {0};
449         unsigned long start_pfn = start >> PAGE_SHIFT;
450
451         pgdat = arch_alloc_nodedata(nid);
452         if (!pgdat)
453                 return NULL;
454
455         arch_refresh_nodedata(nid, pgdat);
456
457         /* we can use NODE_DATA(nid) from here */
458
459         /* init node's zones as empty zones, we don't have any present pages.*/
460         free_area_init_node(nid, zones_size, start_pfn, zholes_size);
461
462         return pgdat;
463 }
464
465 static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
466 {
467         arch_refresh_nodedata(nid, NULL);
468         arch_free_nodedata(pgdat);
469         return;
470 }
471
472
473 int add_memory(int nid, u64 start, u64 size)
474 {
475         pg_data_t *pgdat = NULL;
476         int new_pgdat = 0;
477         struct resource *res;
478         int ret;
479
480         res = register_memory_resource(start, size);
481         if (!res)
482                 return -EEXIST;
483
484         if (!node_online(nid)) {
485                 pgdat = hotadd_new_pgdat(nid, start);
486                 if (!pgdat)
487                         return -ENOMEM;
488                 new_pgdat = 1;
489         }
490
491         /* call arch's memory hotadd */
492         ret = arch_add_memory(nid, start, size);
493
494         if (ret < 0)
495                 goto error;
496
497         /* we online node here. we can't roll back from here. */
498         node_set_online(nid);
499
500         cpuset_track_online_nodes();
501
502         if (new_pgdat) {
503                 ret = register_one_node(nid);
504                 /*
505                  * If sysfs file of new node can't create, cpu on the node
506                  * can't be hot-added. There is no rollback way now.
507                  * So, check by BUG_ON() to catch it reluctantly..
508                  */
509                 BUG_ON(ret);
510         }
511
512         return ret;
513 error:
514         /* rollback pgdat allocation and others */
515         if (new_pgdat)
516                 rollback_node_hotadd(nid, pgdat);
517         if (res)
518                 release_memory_resource(res);
519
520         return ret;
521 }
522 EXPORT_SYMBOL_GPL(add_memory);
523
524 #ifdef CONFIG_MEMORY_HOTREMOVE
525 /*
526  * Confirm all pages in a range [start, end) is belongs to the same zone.
527  */
528 static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
529 {
530         unsigned long pfn;
531         struct zone *zone = NULL;
532         struct page *page;
533         int i;
534         for (pfn = start_pfn;
535              pfn < end_pfn;
536              pfn += MAX_ORDER_NR_PAGES) {
537                 i = 0;
538                 /* This is just a CONFIG_HOLES_IN_ZONE check.*/
539                 while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i))
540                         i++;
541                 if (i == MAX_ORDER_NR_PAGES)
542                         continue;
543                 page = pfn_to_page(pfn + i);
544                 if (zone && page_zone(page) != zone)
545                         return 0;
546                 zone = page_zone(page);
547         }
548         return 1;
549 }
550
551 /*
552  * Scanning pfn is much easier than scanning lru list.
553  * Scan pfn from start to end and Find LRU page.
554  */
555 int scan_lru_pages(unsigned long start, unsigned long end)
556 {
557         unsigned long pfn;
558         struct page *page;
559         for (pfn = start; pfn < end; pfn++) {
560                 if (pfn_valid(pfn)) {
561                         page = pfn_to_page(pfn);
562                         if (PageLRU(page))
563                                 return pfn;
564                 }
565         }
566         return 0;
567 }
568
569 static struct page *
570 hotremove_migrate_alloc(struct page *page,
571                         unsigned long private,
572                         int **x)
573 {
574         /* This should be improoooooved!! */
575         return alloc_page(GFP_HIGHUSER_PAGECACHE);
576 }
577
578
579 #define NR_OFFLINE_AT_ONCE_PAGES        (256)
580 static int
581 do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
582 {
583         unsigned long pfn;
584         struct page *page;
585         int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
586         int not_managed = 0;
587         int ret = 0;
588         LIST_HEAD(source);
589
590         for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
591                 if (!pfn_valid(pfn))
592                         continue;
593                 page = pfn_to_page(pfn);
594                 if (!page_count(page))
595                         continue;
596                 /*
597                  * We can skip free pages. And we can only deal with pages on
598                  * LRU.
599                  */
600                 ret = isolate_lru_page(page, &source);
601                 if (!ret) { /* Success */
602                         move_pages--;
603                 } else {
604                         /* Becasue we don't have big zone->lock. we should
605                            check this again here. */
606                         if (page_count(page))
607                                 not_managed++;
608 #ifdef CONFIG_DEBUG_VM
609                         printk(KERN_INFO "removing from LRU failed"
610                                          " %lx/%d/%lx\n",
611                                 pfn, page_count(page), page->flags);
612 #endif
613                 }
614         }
615         ret = -EBUSY;
616         if (not_managed) {
617                 if (!list_empty(&source))
618                         putback_lru_pages(&source);
619                 goto out;
620         }
621         ret = 0;
622         if (list_empty(&source))
623                 goto out;
624         /* this function returns # of failed pages */
625         ret = migrate_pages(&source, hotremove_migrate_alloc, 0);
626
627 out:
628         return ret;
629 }
630
631 /*
632  * remove from free_area[] and mark all as Reserved.
633  */
634 static int
635 offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
636                         void *data)
637 {
638         __offline_isolated_pages(start, start + nr_pages);
639         return 0;
640 }
641
642 static void
643 offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
644 {
645         walk_memory_resource(start_pfn, end_pfn - start_pfn, NULL,
646                                 offline_isolated_pages_cb);
647 }
648
649 /*
650  * Check all pages in range, recoreded as memory resource, are isolated.
651  */
652 static int
653 check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
654                         void *data)
655 {
656         int ret;
657         long offlined = *(long *)data;
658         ret = test_pages_isolated(start_pfn, start_pfn + nr_pages);
659         offlined = nr_pages;
660         if (!ret)
661                 *(long *)data += offlined;
662         return ret;
663 }
664
665 static long
666 check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
667 {
668         long offlined = 0;
669         int ret;
670
671         ret = walk_memory_resource(start_pfn, end_pfn - start_pfn, &offlined,
672                         check_pages_isolated_cb);
673         if (ret < 0)
674                 offlined = (long)ret;
675         return offlined;
676 }
677
678 int offline_pages(unsigned long start_pfn,
679                   unsigned long end_pfn, unsigned long timeout)
680 {
681         unsigned long pfn, nr_pages, expire;
682         long offlined_pages;
683         int ret, drain, retry_max, node;
684         struct zone *zone;
685         struct memory_notify arg;
686
687         BUG_ON(start_pfn >= end_pfn);
688         /* at least, alignment against pageblock is necessary */
689         if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
690                 return -EINVAL;
691         if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
692                 return -EINVAL;
693         /* This makes hotplug much easier...and readable.
694            we assume this for now. .*/
695         if (!test_pages_in_a_zone(start_pfn, end_pfn))
696                 return -EINVAL;
697
698         zone = page_zone(pfn_to_page(start_pfn));
699         node = zone_to_nid(zone);
700         nr_pages = end_pfn - start_pfn;
701
702         /* set above range as isolated */
703         ret = start_isolate_page_range(start_pfn, end_pfn);
704         if (ret)
705                 return ret;
706
707         arg.start_pfn = start_pfn;
708         arg.nr_pages = nr_pages;
709         arg.status_change_nid = -1;
710         if (nr_pages >= node_present_pages(node))
711                 arg.status_change_nid = node;
712
713         ret = memory_notify(MEM_GOING_OFFLINE, &arg);
714         ret = notifier_to_errno(ret);
715         if (ret)
716                 goto failed_removal;
717
718         pfn = start_pfn;
719         expire = jiffies + timeout;
720         drain = 0;
721         retry_max = 5;
722 repeat:
723         /* start memory hot removal */
724         ret = -EAGAIN;
725         if (time_after(jiffies, expire))
726                 goto failed_removal;
727         ret = -EINTR;
728         if (signal_pending(current))
729                 goto failed_removal;
730         ret = 0;
731         if (drain) {
732                 lru_add_drain_all();
733                 flush_scheduled_work();
734                 cond_resched();
735                 drain_all_pages();
736         }
737
738         pfn = scan_lru_pages(start_pfn, end_pfn);
739         if (pfn) { /* We have page on LRU */
740                 ret = do_migrate_range(pfn, end_pfn);
741                 if (!ret) {
742                         drain = 1;
743                         goto repeat;
744                 } else {
745                         if (ret < 0)
746                                 if (--retry_max == 0)
747                                         goto failed_removal;
748                         yield();
749                         drain = 1;
750                         goto repeat;
751                 }
752         }
753         /* drain all zone's lru pagevec, this is asyncronous... */
754         lru_add_drain_all();
755         flush_scheduled_work();
756         yield();
757         /* drain pcp pages , this is synchrouns. */
758         drain_all_pages();
759         /* check again */
760         offlined_pages = check_pages_isolated(start_pfn, end_pfn);
761         if (offlined_pages < 0) {
762                 ret = -EBUSY;
763                 goto failed_removal;
764         }
765         printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages);
766         /* Ok, all of our target is islaoted.
767            We cannot do rollback at this point. */
768         offline_isolated_pages(start_pfn, end_pfn);
769         /* reset pagetype flags and makes migrate type to be MOVABLE */
770         undo_isolate_page_range(start_pfn, end_pfn);
771         /* removal success */
772         zone->present_pages -= offlined_pages;
773         zone->zone_pgdat->node_present_pages -= offlined_pages;
774         totalram_pages -= offlined_pages;
775         num_physpages -= offlined_pages;
776
777         vm_total_pages = nr_free_pagecache_pages();
778         writeback_set_ratelimit();
779
780         memory_notify(MEM_OFFLINE, &arg);
781         return 0;
782
783 failed_removal:
784         printk(KERN_INFO "memory offlining %lx to %lx failed\n",
785                 start_pfn, end_pfn);
786         memory_notify(MEM_CANCEL_OFFLINE, &arg);
787         /* pushback to free area */
788         undo_isolate_page_range(start_pfn, end_pfn);
789
790         return ret;
791 }
792 #else
793 int remove_memory(u64 start, u64 size)
794 {
795         return -EINVAL;
796 }
797 EXPORT_SYMBOL_GPL(remove_memory);
798 #endif /* CONFIG_MEMORY_HOTREMOVE */