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Christoph Lameterb20a3502006-03-22 00:09:12 -08001/*
2 * Memory Migration functionality - linux/mm/migration.c
3 *
4 * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
5 *
6 * Page migration was first developed in the context of the memory hotplug
7 * project. The main authors of the migration code are:
8 *
9 * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
10 * Hirokazu Takahashi <taka@valinux.co.jp>
11 * Dave Hansen <haveblue@us.ibm.com>
12 * Christoph Lameter <clameter@sgi.com>
13 */
14
15#include <linux/migrate.h>
16#include <linux/module.h>
17#include <linux/swap.h>
Christoph Lameter06972122006-06-23 02:03:35 -070018#include <linux/swapops.h>
Christoph Lameterb20a3502006-03-22 00:09:12 -080019#include <linux/pagemap.h>
Christoph Lametere23ca002006-04-10 22:52:57 -070020#include <linux/buffer_head.h>
Christoph Lameterb20a3502006-03-22 00:09:12 -080021#include <linux/mm_inline.h>
22#include <linux/pagevec.h>
23#include <linux/rmap.h>
24#include <linux/topology.h>
25#include <linux/cpu.h>
26#include <linux/cpuset.h>
Christoph Lameter04e62a22006-06-23 02:03:38 -070027#include <linux/writeback.h>
Christoph Lameter742755a2006-06-23 02:03:55 -070028#include <linux/mempolicy.h>
29#include <linux/vmalloc.h>
David Quigley86c3a762006-06-23 02:04:02 -070030#include <linux/security.h>
Christoph Lameterb20a3502006-03-22 00:09:12 -080031
32#include "internal.h"
33
Christoph Lameterb20a3502006-03-22 00:09:12 -080034#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
35
36/*
37 * Isolate one page from the LRU lists. If successful put it onto
38 * the indicated list with elevated page count.
39 *
40 * Result:
41 * -EBUSY: page not on LRU list
42 * 0: page removed from LRU list and added to the specified list.
43 */
44int isolate_lru_page(struct page *page, struct list_head *pagelist)
45{
46 int ret = -EBUSY;
47
48 if (PageLRU(page)) {
49 struct zone *zone = page_zone(page);
50
51 spin_lock_irq(&zone->lru_lock);
KAMEZAWA Hiroyuki3dd9fe82007-07-26 10:41:08 -070052 if (PageLRU(page) && get_page_unless_zero(page)) {
Christoph Lameterb20a3502006-03-22 00:09:12 -080053 ret = 0;
Christoph Lameterb20a3502006-03-22 00:09:12 -080054 ClearPageLRU(page);
55 if (PageActive(page))
56 del_page_from_active_list(zone, page);
57 else
58 del_page_from_inactive_list(zone, page);
59 list_add_tail(&page->lru, pagelist);
60 }
61 spin_unlock_irq(&zone->lru_lock);
62 }
63 return ret;
64}
65
66/*
Christoph Lameter742755a2006-06-23 02:03:55 -070067 * migrate_prep() needs to be called before we start compiling a list of pages
68 * to be migrated using isolate_lru_page().
Christoph Lameterb20a3502006-03-22 00:09:12 -080069 */
70int migrate_prep(void)
71{
Christoph Lameterb20a3502006-03-22 00:09:12 -080072 /*
73 * Clear the LRU lists so pages can be isolated.
74 * Note that pages may be moved off the LRU after we have
75 * drained them. Those pages will fail to migrate like other
76 * pages that may be busy.
77 */
78 lru_add_drain_all();
79
80 return 0;
81}
82
83static inline void move_to_lru(struct page *page)
84{
Christoph Lameterb20a3502006-03-22 00:09:12 -080085 if (PageActive(page)) {
86 /*
87 * lru_cache_add_active checks that
88 * the PG_active bit is off.
89 */
90 ClearPageActive(page);
91 lru_cache_add_active(page);
92 } else {
93 lru_cache_add(page);
94 }
95 put_page(page);
96}
97
98/*
99 * Add isolated pages on the list back to the LRU.
100 *
101 * returns the number of pages put back.
102 */
103int putback_lru_pages(struct list_head *l)
104{
105 struct page *page;
106 struct page *page2;
107 int count = 0;
108
109 list_for_each_entry_safe(page, page2, l, lru) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700110 list_del(&page->lru);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800111 move_to_lru(page);
112 count++;
113 }
114 return count;
115}
116
Christoph Lameter06972122006-06-23 02:03:35 -0700117static inline int is_swap_pte(pte_t pte)
118{
119 return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);
120}
121
122/*
123 * Restore a potential migration pte to a working pte entry
124 */
Christoph Lameter04e62a22006-06-23 02:03:38 -0700125static void remove_migration_pte(struct vm_area_struct *vma,
Christoph Lameter06972122006-06-23 02:03:35 -0700126 struct page *old, struct page *new)
127{
128 struct mm_struct *mm = vma->vm_mm;
129 swp_entry_t entry;
130 pgd_t *pgd;
131 pud_t *pud;
132 pmd_t *pmd;
133 pte_t *ptep, pte;
134 spinlock_t *ptl;
Christoph Lameter04e62a22006-06-23 02:03:38 -0700135 unsigned long addr = page_address_in_vma(new, vma);
136
137 if (addr == -EFAULT)
138 return;
Christoph Lameter06972122006-06-23 02:03:35 -0700139
140 pgd = pgd_offset(mm, addr);
141 if (!pgd_present(*pgd))
142 return;
143
144 pud = pud_offset(pgd, addr);
145 if (!pud_present(*pud))
146 return;
147
148 pmd = pmd_offset(pud, addr);
149 if (!pmd_present(*pmd))
150 return;
151
152 ptep = pte_offset_map(pmd, addr);
153
154 if (!is_swap_pte(*ptep)) {
155 pte_unmap(ptep);
156 return;
157 }
158
159 ptl = pte_lockptr(mm, pmd);
160 spin_lock(ptl);
161 pte = *ptep;
162 if (!is_swap_pte(pte))
163 goto out;
164
165 entry = pte_to_swp_entry(pte);
166
167 if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
168 goto out;
169
Christoph Lameter06972122006-06-23 02:03:35 -0700170 get_page(new);
171 pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
172 if (is_write_migration_entry(entry))
173 pte = pte_mkwrite(pte);
KAMEZAWA Hiroyuki97ee0522007-10-16 01:25:43 -0700174 flush_cache_page(vma, addr, pte_pfn(pte));
Christoph Lameter06972122006-06-23 02:03:35 -0700175 set_pte_at(mm, addr, ptep, pte);
Christoph Lameter04e62a22006-06-23 02:03:38 -0700176
177 if (PageAnon(new))
178 page_add_anon_rmap(new, vma, addr);
179 else
180 page_add_file_rmap(new);
181
182 /* No need to invalidate - it was non-present before */
183 update_mmu_cache(vma, addr, pte);
Christoph Lameter04e62a22006-06-23 02:03:38 -0700184
Christoph Lameter06972122006-06-23 02:03:35 -0700185out:
186 pte_unmap_unlock(ptep, ptl);
187}
188
189/*
Christoph Lameter04e62a22006-06-23 02:03:38 -0700190 * Note that remove_file_migration_ptes will only work on regular mappings,
191 * Nonlinear mappings do not use migration entries.
192 */
193static void remove_file_migration_ptes(struct page *old, struct page *new)
194{
195 struct vm_area_struct *vma;
196 struct address_space *mapping = page_mapping(new);
197 struct prio_tree_iter iter;
198 pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
199
200 if (!mapping)
201 return;
202
203 spin_lock(&mapping->i_mmap_lock);
204
205 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff)
206 remove_migration_pte(vma, old, new);
207
208 spin_unlock(&mapping->i_mmap_lock);
209}
210
211/*
Christoph Lameter06972122006-06-23 02:03:35 -0700212 * Must hold mmap_sem lock on at least one of the vmas containing
213 * the page so that the anon_vma cannot vanish.
214 */
Christoph Lameter04e62a22006-06-23 02:03:38 -0700215static void remove_anon_migration_ptes(struct page *old, struct page *new)
Christoph Lameter06972122006-06-23 02:03:35 -0700216{
217 struct anon_vma *anon_vma;
218 struct vm_area_struct *vma;
219 unsigned long mapping;
220
221 mapping = (unsigned long)new->mapping;
222
223 if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
224 return;
225
226 /*
227 * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
228 */
229 anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
230 spin_lock(&anon_vma->lock);
231
232 list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
Christoph Lameter04e62a22006-06-23 02:03:38 -0700233 remove_migration_pte(vma, old, new);
Christoph Lameter06972122006-06-23 02:03:35 -0700234
235 spin_unlock(&anon_vma->lock);
236}
237
238/*
Christoph Lameter04e62a22006-06-23 02:03:38 -0700239 * Get rid of all migration entries and replace them by
240 * references to the indicated page.
241 */
242static void remove_migration_ptes(struct page *old, struct page *new)
243{
244 if (PageAnon(new))
245 remove_anon_migration_ptes(old, new);
246 else
247 remove_file_migration_ptes(old, new);
248}
249
250/*
Christoph Lameter06972122006-06-23 02:03:35 -0700251 * Something used the pte of a page under migration. We need to
252 * get to the page and wait until migration is finished.
253 * When we return from this function the fault will be retried.
254 *
255 * This function is called from do_swap_page().
256 */
257void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
258 unsigned long address)
259{
260 pte_t *ptep, pte;
261 spinlock_t *ptl;
262 swp_entry_t entry;
263 struct page *page;
264
265 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
266 pte = *ptep;
267 if (!is_swap_pte(pte))
268 goto out;
269
270 entry = pte_to_swp_entry(pte);
271 if (!is_migration_entry(entry))
272 goto out;
273
274 page = migration_entry_to_page(entry);
275
276 get_page(page);
277 pte_unmap_unlock(ptep, ptl);
278 wait_on_page_locked(page);
279 put_page(page);
280 return;
281out:
282 pte_unmap_unlock(ptep, ptl);
283}
284
Christoph Lameterb20a3502006-03-22 00:09:12 -0800285/*
Christoph Lameterc3fcf8a2006-06-23 02:03:32 -0700286 * Replace the page in the mapping.
Christoph Lameter5b5c7122006-06-23 02:03:29 -0700287 *
288 * The number of remaining references must be:
289 * 1 for anonymous pages without a mapping
290 * 2 for pages with a mapping
291 * 3 for pages with a mapping and PagePrivate set.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800292 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700293static int migrate_page_move_mapping(struct address_space *mapping,
294 struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800295{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800296 void **pslot;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800297
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700298 if (!mapping) {
Christoph Lameter0e8c7d02007-04-23 14:41:09 -0700299 /* Anonymous page without mapping */
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700300 if (page_count(page) != 1)
301 return -EAGAIN;
302 return 0;
303 }
304
Christoph Lameterb20a3502006-03-22 00:09:12 -0800305 write_lock_irq(&mapping->tree_lock);
306
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800307 pslot = radix_tree_lookup_slot(&mapping->page_tree,
308 page_index(page));
Christoph Lameterb20a3502006-03-22 00:09:12 -0800309
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700310 if (page_count(page) != 2 + !!PagePrivate(page) ||
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800311 (struct page *)radix_tree_deref_slot(pslot) != page) {
Christoph Lameterb20a3502006-03-22 00:09:12 -0800312 write_unlock_irq(&mapping->tree_lock);
Christoph Lametere23ca002006-04-10 22:52:57 -0700313 return -EAGAIN;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800314 }
315
316 /*
317 * Now we know that no one else is looking at the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800318 */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800319 get_page(newpage); /* add cache reference */
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700320#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800321 if (PageSwapCache(page)) {
322 SetPageSwapCache(newpage);
323 set_page_private(newpage, page_private(page));
324 }
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700325#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800326
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800327 radix_tree_replace_slot(pslot, newpage);
328
329 /*
330 * Drop cache reference from old page.
331 * We know this isn't the last reference.
332 */
Christoph Lameterb20a3502006-03-22 00:09:12 -0800333 __put_page(page);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800334
Christoph Lameter0e8c7d02007-04-23 14:41:09 -0700335 /*
336 * If moved to a different zone then also account
337 * the page for that zone. Other VM counters will be
338 * taken care of when we establish references to the
339 * new page and drop references to the old page.
340 *
341 * Note that anonymous pages are accounted for
342 * via NR_FILE_PAGES and NR_ANON_PAGES if they
343 * are mapped to swap space.
344 */
345 __dec_zone_page_state(page, NR_FILE_PAGES);
346 __inc_zone_page_state(newpage, NR_FILE_PAGES);
347
Christoph Lameterb20a3502006-03-22 00:09:12 -0800348 write_unlock_irq(&mapping->tree_lock);
349
350 return 0;
351}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800352
353/*
354 * Copy the page to its new location
355 */
Christoph Lametere7340f72006-06-23 02:03:29 -0700356static void migrate_page_copy(struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800357{
358 copy_highpage(newpage, page);
359
360 if (PageError(page))
361 SetPageError(newpage);
362 if (PageReferenced(page))
363 SetPageReferenced(newpage);
364 if (PageUptodate(page))
365 SetPageUptodate(newpage);
366 if (PageActive(page))
367 SetPageActive(newpage);
368 if (PageChecked(page))
369 SetPageChecked(newpage);
370 if (PageMappedToDisk(page))
371 SetPageMappedToDisk(newpage);
372
373 if (PageDirty(page)) {
374 clear_page_dirty_for_io(page);
375 set_page_dirty(newpage);
376 }
377
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700378#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800379 ClearPageSwapCache(page);
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700380#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800381 ClearPageActive(page);
382 ClearPagePrivate(page);
383 set_page_private(page, 0);
384 page->mapping = NULL;
385
386 /*
387 * If any waiters have accumulated on the new page then
388 * wake them up.
389 */
390 if (PageWriteback(newpage))
391 end_page_writeback(newpage);
392}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800393
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700394/************************************************************
395 * Migration functions
396 ***********************************************************/
397
398/* Always fail migration. Used for mappings that are not movable */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700399int fail_migrate_page(struct address_space *mapping,
400 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700401{
402 return -EIO;
403}
404EXPORT_SYMBOL(fail_migrate_page);
405
Christoph Lameterb20a3502006-03-22 00:09:12 -0800406/*
407 * Common logic to directly migrate a single page suitable for
408 * pages that do not use PagePrivate.
409 *
410 * Pages are locked upon entry and exit.
411 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700412int migrate_page(struct address_space *mapping,
413 struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800414{
415 int rc;
416
417 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
418
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700419 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800420
421 if (rc)
422 return rc;
423
424 migrate_page_copy(newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800425 return 0;
426}
427EXPORT_SYMBOL(migrate_page);
428
David Howells93614012006-09-30 20:45:40 +0200429#ifdef CONFIG_BLOCK
Christoph Lameterb20a3502006-03-22 00:09:12 -0800430/*
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700431 * Migration function for pages with buffers. This function can only be used
432 * if the underlying filesystem guarantees that no other references to "page"
433 * exist.
434 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700435int buffer_migrate_page(struct address_space *mapping,
436 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700437{
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700438 struct buffer_head *bh, *head;
439 int rc;
440
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700441 if (!page_has_buffers(page))
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700442 return migrate_page(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700443
444 head = page_buffers(page);
445
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700446 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700447
448 if (rc)
449 return rc;
450
451 bh = head;
452 do {
453 get_bh(bh);
454 lock_buffer(bh);
455 bh = bh->b_this_page;
456
457 } while (bh != head);
458
459 ClearPagePrivate(page);
460 set_page_private(newpage, page_private(page));
461 set_page_private(page, 0);
462 put_page(page);
463 get_page(newpage);
464
465 bh = head;
466 do {
467 set_bh_page(bh, newpage, bh_offset(bh));
468 bh = bh->b_this_page;
469
470 } while (bh != head);
471
472 SetPagePrivate(newpage);
473
474 migrate_page_copy(newpage, page);
475
476 bh = head;
477 do {
478 unlock_buffer(bh);
479 put_bh(bh);
480 bh = bh->b_this_page;
481
482 } while (bh != head);
483
484 return 0;
485}
486EXPORT_SYMBOL(buffer_migrate_page);
David Howells93614012006-09-30 20:45:40 +0200487#endif
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700488
Christoph Lameter04e62a22006-06-23 02:03:38 -0700489/*
490 * Writeback a page to clean the dirty state
491 */
492static int writeout(struct address_space *mapping, struct page *page)
493{
494 struct writeback_control wbc = {
495 .sync_mode = WB_SYNC_NONE,
496 .nr_to_write = 1,
497 .range_start = 0,
498 .range_end = LLONG_MAX,
499 .nonblocking = 1,
500 .for_reclaim = 1
501 };
502 int rc;
503
504 if (!mapping->a_ops->writepage)
505 /* No write method for the address space */
506 return -EINVAL;
507
508 if (!clear_page_dirty_for_io(page))
509 /* Someone else already triggered a write */
510 return -EAGAIN;
511
512 /*
513 * A dirty page may imply that the underlying filesystem has
514 * the page on some queue. So the page must be clean for
515 * migration. Writeout may mean we loose the lock and the
516 * page state is no longer what we checked for earlier.
517 * At this point we know that the migration attempt cannot
518 * be successful.
519 */
520 remove_migration_ptes(page, page);
521
522 rc = mapping->a_ops->writepage(page, &wbc);
523 if (rc < 0)
524 /* I/O Error writing */
525 return -EIO;
526
527 if (rc != AOP_WRITEPAGE_ACTIVATE)
528 /* unlocked. Relock */
529 lock_page(page);
530
531 return -EAGAIN;
532}
533
534/*
535 * Default handling if a filesystem does not provide a migration function.
536 */
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700537static int fallback_migrate_page(struct address_space *mapping,
538 struct page *newpage, struct page *page)
539{
Christoph Lameter04e62a22006-06-23 02:03:38 -0700540 if (PageDirty(page))
541 return writeout(mapping, page);
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700542
543 /*
544 * Buffers may be managed in a filesystem specific way.
545 * We must have no buffers or drop them.
546 */
David Howellsb398f6b2006-08-29 19:05:58 +0100547 if (PagePrivate(page) &&
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700548 !try_to_release_page(page, GFP_KERNEL))
549 return -EAGAIN;
550
551 return migrate_page(mapping, newpage, page);
552}
553
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700554/*
Christoph Lametere24f0b82006-06-23 02:03:51 -0700555 * Move a page to a newly allocated page
556 * The page is locked and all ptes have been successfully removed.
557 *
558 * The new page will have replaced the old page if this function
559 * is successful.
560 */
561static int move_to_new_page(struct page *newpage, struct page *page)
562{
563 struct address_space *mapping;
564 int rc;
565
566 /*
567 * Block others from accessing the page when we get around to
568 * establishing additional references. We are the only one
569 * holding a reference to the new page at this point.
570 */
571 if (TestSetPageLocked(newpage))
572 BUG();
573
574 /* Prepare mapping for the new page.*/
575 newpage->index = page->index;
576 newpage->mapping = page->mapping;
577
578 mapping = page_mapping(page);
579 if (!mapping)
580 rc = migrate_page(mapping, newpage, page);
581 else if (mapping->a_ops->migratepage)
582 /*
583 * Most pages have a mapping and most filesystems
584 * should provide a migration function. Anonymous
585 * pages are part of swap space which also has its
586 * own migration function. This is the most common
587 * path for page migration.
588 */
589 rc = mapping->a_ops->migratepage(mapping,
590 newpage, page);
591 else
592 rc = fallback_migrate_page(mapping, newpage, page);
593
594 if (!rc)
595 remove_migration_ptes(page, newpage);
596 else
597 newpage->mapping = NULL;
598
599 unlock_page(newpage);
600
601 return rc;
602}
603
604/*
605 * Obtain the lock on page, remove all ptes and migrate the page
606 * to the newly allocated page in newpage.
607 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700608static int unmap_and_move(new_page_t get_new_page, unsigned long private,
609 struct page *page, int force)
Christoph Lametere24f0b82006-06-23 02:03:51 -0700610{
611 int rc = 0;
Christoph Lameter742755a2006-06-23 02:03:55 -0700612 int *result = NULL;
613 struct page *newpage = get_new_page(page, private, &result);
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700614 int rcu_locked = 0;
Christoph Lameter95a402c2006-06-23 02:03:53 -0700615
616 if (!newpage)
617 return -ENOMEM;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700618
619 if (page_count(page) == 1)
620 /* page was freed from under us. So we are done. */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700621 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700622
623 rc = -EAGAIN;
624 if (TestSetPageLocked(page)) {
625 if (!force)
Christoph Lameter95a402c2006-06-23 02:03:53 -0700626 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700627 lock_page(page);
628 }
629
630 if (PageWriteback(page)) {
631 if (!force)
632 goto unlock;
633 wait_on_page_writeback(page);
634 }
Christoph Lametere24f0b82006-06-23 02:03:51 -0700635 /*
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700636 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
637 * we cannot notice that anon_vma is freed while we migrates a page.
638 * This rcu_read_lock() delays freeing anon_vma pointer until the end
639 * of migration. File cache pages are no problem because of page_lock()
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700640 * File Caches may use write_page() or lock_page() in migration, then,
641 * just care Anon page here.
Christoph Lametere24f0b82006-06-23 02:03:51 -0700642 */
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700643 if (PageAnon(page)) {
644 rcu_read_lock();
645 rcu_locked = 1;
646 }
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700647 /*
648 * This is a corner case handling.
649 * When a new swap-cache is read into, it is linked to LRU
650 * and treated as swapcache but has no rmap yet.
651 * Calling try_to_unmap() against a page->mapping==NULL page is
652 * BUG. So handle it here.
653 */
654 if (!page->mapping)
655 goto rcu_unlock;
656 /* Establish migration ptes or remove ptes */
Christoph Lametere6a15302006-06-25 05:46:49 -0700657 try_to_unmap(page, 1);
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700658
Christoph Lametere6a15302006-06-25 05:46:49 -0700659 if (!page_mapped(page))
660 rc = move_to_new_page(newpage, page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700661
662 if (rc)
663 remove_migration_ptes(page, page);
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700664rcu_unlock:
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700665 if (rcu_locked)
666 rcu_read_unlock();
Christoph Lametere6a15302006-06-25 05:46:49 -0700667
Christoph Lametere24f0b82006-06-23 02:03:51 -0700668unlock:
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700669
Christoph Lametere24f0b82006-06-23 02:03:51 -0700670 unlock_page(page);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700671
Christoph Lametere24f0b82006-06-23 02:03:51 -0700672 if (rc != -EAGAIN) {
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700673 /*
674 * A page that has been migrated has all references
675 * removed and will be freed. A page that has not been
676 * migrated will have kepts its references and be
677 * restored.
678 */
679 list_del(&page->lru);
680 move_to_lru(page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700681 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700682
683move_newpage:
684 /*
685 * Move the new page to the LRU. If migration was not successful
686 * then this will free the page.
687 */
688 move_to_lru(newpage);
Christoph Lameter742755a2006-06-23 02:03:55 -0700689 if (result) {
690 if (rc)
691 *result = rc;
692 else
693 *result = page_to_nid(newpage);
694 }
Christoph Lametere24f0b82006-06-23 02:03:51 -0700695 return rc;
696}
697
698/*
Christoph Lameterb20a3502006-03-22 00:09:12 -0800699 * migrate_pages
700 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700701 * The function takes one list of pages to migrate and a function
702 * that determines from the page to be migrated and the private data
703 * the target of the move and allocates the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800704 *
705 * The function returns after 10 attempts or if no pages
706 * are movable anymore because to has become empty
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700707 * or no retryable pages exist anymore. All pages will be
708 * retruned to the LRU or freed.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800709 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700710 * Return: Number of pages not migrated or error code.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800711 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700712int migrate_pages(struct list_head *from,
713 new_page_t get_new_page, unsigned long private)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800714{
Christoph Lametere24f0b82006-06-23 02:03:51 -0700715 int retry = 1;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800716 int nr_failed = 0;
717 int pass = 0;
718 struct page *page;
719 struct page *page2;
720 int swapwrite = current->flags & PF_SWAPWRITE;
721 int rc;
722
723 if (!swapwrite)
724 current->flags |= PF_SWAPWRITE;
725
Christoph Lametere24f0b82006-06-23 02:03:51 -0700726 for(pass = 0; pass < 10 && retry; pass++) {
727 retry = 0;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800728
Christoph Lametere24f0b82006-06-23 02:03:51 -0700729 list_for_each_entry_safe(page, page2, from, lru) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700730 cond_resched();
Christoph Lameterb20a3502006-03-22 00:09:12 -0800731
Christoph Lameter95a402c2006-06-23 02:03:53 -0700732 rc = unmap_and_move(get_new_page, private,
733 page, pass > 2);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800734
Christoph Lametere24f0b82006-06-23 02:03:51 -0700735 switch(rc) {
Christoph Lameter95a402c2006-06-23 02:03:53 -0700736 case -ENOMEM:
737 goto out;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700738 case -EAGAIN:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700739 retry++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700740 break;
741 case 0:
Christoph Lametere24f0b82006-06-23 02:03:51 -0700742 break;
743 default:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700744 /* Permanent failure */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700745 nr_failed++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700746 break;
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700747 }
Christoph Lameterb20a3502006-03-22 00:09:12 -0800748 }
749 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700750 rc = 0;
751out:
Christoph Lameterb20a3502006-03-22 00:09:12 -0800752 if (!swapwrite)
753 current->flags &= ~PF_SWAPWRITE;
754
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700755 putback_lru_pages(from);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700756
757 if (rc)
758 return rc;
759
Christoph Lameterb20a3502006-03-22 00:09:12 -0800760 return nr_failed + retry;
761}
762
Christoph Lameter742755a2006-06-23 02:03:55 -0700763#ifdef CONFIG_NUMA
764/*
765 * Move a list of individual pages
766 */
767struct page_to_node {
768 unsigned long addr;
769 struct page *page;
770 int node;
771 int status;
772};
773
774static struct page *new_page_node(struct page *p, unsigned long private,
775 int **result)
776{
777 struct page_to_node *pm = (struct page_to_node *)private;
778
779 while (pm->node != MAX_NUMNODES && pm->page != p)
780 pm++;
781
782 if (pm->node == MAX_NUMNODES)
783 return NULL;
784
785 *result = &pm->status;
786
Mel Gorman769848c2007-07-17 04:03:05 -0700787 return alloc_pages_node(pm->node,
788 GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);
Christoph Lameter742755a2006-06-23 02:03:55 -0700789}
790
791/*
792 * Move a set of pages as indicated in the pm array. The addr
793 * field must be set to the virtual address of the page to be moved
794 * and the node number must contain a valid target node.
795 */
796static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
797 int migrate_all)
798{
799 int err;
800 struct page_to_node *pp;
801 LIST_HEAD(pagelist);
802
803 down_read(&mm->mmap_sem);
804
805 /*
806 * Build a list of pages to migrate
807 */
808 migrate_prep();
809 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
810 struct vm_area_struct *vma;
811 struct page *page;
812
813 /*
814 * A valid page pointer that will not match any of the
815 * pages that will be moved.
816 */
817 pp->page = ZERO_PAGE(0);
818
819 err = -EFAULT;
820 vma = find_vma(mm, pp->addr);
Christoph Lameter0dc952d2007-03-05 00:30:33 -0800821 if (!vma || !vma_migratable(vma))
Christoph Lameter742755a2006-06-23 02:03:55 -0700822 goto set_status;
823
824 page = follow_page(vma, pp->addr, FOLL_GET);
825 err = -ENOENT;
826 if (!page)
827 goto set_status;
828
829 if (PageReserved(page)) /* Check for zero page */
830 goto put_and_set;
831
832 pp->page = page;
833 err = page_to_nid(page);
834
835 if (err == pp->node)
836 /*
837 * Node already in the right place
838 */
839 goto put_and_set;
840
841 err = -EACCES;
842 if (page_mapcount(page) > 1 &&
843 !migrate_all)
844 goto put_and_set;
845
846 err = isolate_lru_page(page, &pagelist);
847put_and_set:
848 /*
849 * Either remove the duplicate refcount from
850 * isolate_lru_page() or drop the page ref if it was
851 * not isolated.
852 */
853 put_page(page);
854set_status:
855 pp->status = err;
856 }
857
858 if (!list_empty(&pagelist))
859 err = migrate_pages(&pagelist, new_page_node,
860 (unsigned long)pm);
861 else
862 err = -ENOENT;
863
864 up_read(&mm->mmap_sem);
865 return err;
866}
867
868/*
869 * Determine the nodes of a list of pages. The addr in the pm array
870 * must have been set to the virtual address of which we want to determine
871 * the node number.
872 */
873static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
874{
875 down_read(&mm->mmap_sem);
876
877 for ( ; pm->node != MAX_NUMNODES; pm++) {
878 struct vm_area_struct *vma;
879 struct page *page;
880 int err;
881
882 err = -EFAULT;
883 vma = find_vma(mm, pm->addr);
884 if (!vma)
885 goto set_status;
886
887 page = follow_page(vma, pm->addr, 0);
888 err = -ENOENT;
889 /* Use PageReserved to check for zero page */
890 if (!page || PageReserved(page))
891 goto set_status;
892
893 err = page_to_nid(page);
894set_status:
895 pm->status = err;
896 }
897
898 up_read(&mm->mmap_sem);
899 return 0;
900}
901
902/*
903 * Move a list of pages in the address space of the currently executing
904 * process.
905 */
906asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages,
907 const void __user * __user *pages,
908 const int __user *nodes,
909 int __user *status, int flags)
910{
911 int err = 0;
912 int i;
913 struct task_struct *task;
914 nodemask_t task_nodes;
915 struct mm_struct *mm;
916 struct page_to_node *pm = NULL;
917
918 /* Check flags */
919 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
920 return -EINVAL;
921
922 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
923 return -EPERM;
924
925 /* Find the mm_struct */
926 read_lock(&tasklist_lock);
927 task = pid ? find_task_by_pid(pid) : current;
928 if (!task) {
929 read_unlock(&tasklist_lock);
930 return -ESRCH;
931 }
932 mm = get_task_mm(task);
933 read_unlock(&tasklist_lock);
934
935 if (!mm)
936 return -EINVAL;
937
938 /*
939 * Check if this process has the right to modify the specified
940 * process. The right exists if the process has administrative
941 * capabilities, superuser privileges or the same
942 * userid as the target process.
943 */
944 if ((current->euid != task->suid) && (current->euid != task->uid) &&
945 (current->uid != task->suid) && (current->uid != task->uid) &&
946 !capable(CAP_SYS_NICE)) {
947 err = -EPERM;
948 goto out2;
949 }
950
David Quigley86c3a762006-06-23 02:04:02 -0700951 err = security_task_movememory(task);
952 if (err)
953 goto out2;
954
955
Christoph Lameter742755a2006-06-23 02:03:55 -0700956 task_nodes = cpuset_mems_allowed(task);
957
958 /* Limit nr_pages so that the multiplication may not overflow */
959 if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) {
960 err = -E2BIG;
961 goto out2;
962 }
963
964 pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node));
965 if (!pm) {
966 err = -ENOMEM;
967 goto out2;
968 }
969
970 /*
971 * Get parameters from user space and initialize the pm
972 * array. Return various errors if the user did something wrong.
973 */
974 for (i = 0; i < nr_pages; i++) {
Al Viro9d966d42007-10-14 19:34:10 +0100975 const void __user *p;
Christoph Lameter742755a2006-06-23 02:03:55 -0700976
977 err = -EFAULT;
978 if (get_user(p, pages + i))
979 goto out;
980
981 pm[i].addr = (unsigned long)p;
982 if (nodes) {
983 int node;
984
985 if (get_user(node, nodes + i))
986 goto out;
987
988 err = -ENODEV;
Christoph Lameter56bbd652007-10-16 01:25:35 -0700989 if (!node_state(node, N_HIGH_MEMORY))
Christoph Lameter742755a2006-06-23 02:03:55 -0700990 goto out;
991
992 err = -EACCES;
993 if (!node_isset(node, task_nodes))
994 goto out;
995
996 pm[i].node = node;
Stephen Rothwell8ce08462006-11-02 22:07:28 -0800997 } else
998 pm[i].node = 0; /* anything to not match MAX_NUMNODES */
Christoph Lameter742755a2006-06-23 02:03:55 -0700999 }
1000 /* End marker */
1001 pm[nr_pages].node = MAX_NUMNODES;
1002
1003 if (nodes)
1004 err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL);
1005 else
1006 err = do_pages_stat(mm, pm);
1007
1008 if (err >= 0)
1009 /* Return status information */
1010 for (i = 0; i < nr_pages; i++)
1011 if (put_user(pm[i].status, status + i))
1012 err = -EFAULT;
1013
1014out:
1015 vfree(pm);
1016out2:
1017 mmput(mm);
1018 return err;
1019}
1020#endif
1021
Christoph Lameter7b2259b2006-06-25 05:46:48 -07001022/*
1023 * Call migration functions in the vma_ops that may prepare
1024 * memory in a vm for migration. migration functions may perform
1025 * the migration for vmas that do not have an underlying page struct.
1026 */
1027int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
1028 const nodemask_t *from, unsigned long flags)
1029{
1030 struct vm_area_struct *vma;
1031 int err = 0;
1032
1033 for(vma = mm->mmap; vma->vm_next && !err; vma = vma->vm_next) {
1034 if (vma->vm_ops && vma->vm_ops->migrate) {
1035 err = vma->vm_ops->migrate(vma, to, from, flags);
1036 if (err)
1037 break;
1038 }
1039 }
1040 return err;
1041}