blob: 7a66ca25dc8aa99b77f2a4f041fed0cd8194b6aa [file] [log] [blame]
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);
52 if (PageLRU(page)) {
53 ret = 0;
54 get_page(page);
55 ClearPageLRU(page);
56 if (PageActive(page))
57 del_page_from_active_list(zone, page);
58 else
59 del_page_from_inactive_list(zone, page);
60 list_add_tail(&page->lru, pagelist);
61 }
62 spin_unlock_irq(&zone->lru_lock);
63 }
64 return ret;
65}
66
67/*
Christoph Lameter742755a2006-06-23 02:03:55 -070068 * migrate_prep() needs to be called before we start compiling a list of pages
69 * to be migrated using isolate_lru_page().
Christoph Lameterb20a3502006-03-22 00:09:12 -080070 */
71int migrate_prep(void)
72{
Christoph Lameterb20a3502006-03-22 00:09:12 -080073 /*
74 * Clear the LRU lists so pages can be isolated.
75 * Note that pages may be moved off the LRU after we have
76 * drained them. Those pages will fail to migrate like other
77 * pages that may be busy.
78 */
79 lru_add_drain_all();
80
81 return 0;
82}
83
84static inline void move_to_lru(struct page *page)
85{
Christoph Lameterb20a3502006-03-22 00:09:12 -080086 if (PageActive(page)) {
87 /*
88 * lru_cache_add_active checks that
89 * the PG_active bit is off.
90 */
91 ClearPageActive(page);
92 lru_cache_add_active(page);
93 } else {
94 lru_cache_add(page);
95 }
96 put_page(page);
97}
98
99/*
100 * Add isolated pages on the list back to the LRU.
101 *
102 * returns the number of pages put back.
103 */
104int putback_lru_pages(struct list_head *l)
105{
106 struct page *page;
107 struct page *page2;
108 int count = 0;
109
110 list_for_each_entry_safe(page, page2, l, lru) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700111 list_del(&page->lru);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800112 move_to_lru(page);
113 count++;
114 }
115 return count;
116}
117
Christoph Lameter06972122006-06-23 02:03:35 -0700118static inline int is_swap_pte(pte_t pte)
119{
120 return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);
121}
122
123/*
124 * Restore a potential migration pte to a working pte entry
125 */
Christoph Lameter04e62a22006-06-23 02:03:38 -0700126static void remove_migration_pte(struct vm_area_struct *vma,
Christoph Lameter06972122006-06-23 02:03:35 -0700127 struct page *old, struct page *new)
128{
129 struct mm_struct *mm = vma->vm_mm;
130 swp_entry_t entry;
131 pgd_t *pgd;
132 pud_t *pud;
133 pmd_t *pmd;
134 pte_t *ptep, pte;
135 spinlock_t *ptl;
Christoph Lameter04e62a22006-06-23 02:03:38 -0700136 unsigned long addr = page_address_in_vma(new, vma);
137
138 if (addr == -EFAULT)
139 return;
Christoph Lameter06972122006-06-23 02:03:35 -0700140
141 pgd = pgd_offset(mm, addr);
142 if (!pgd_present(*pgd))
143 return;
144
145 pud = pud_offset(pgd, addr);
146 if (!pud_present(*pud))
147 return;
148
149 pmd = pmd_offset(pud, addr);
150 if (!pmd_present(*pmd))
151 return;
152
153 ptep = pte_offset_map(pmd, addr);
154
155 if (!is_swap_pte(*ptep)) {
156 pte_unmap(ptep);
157 return;
158 }
159
160 ptl = pte_lockptr(mm, pmd);
161 spin_lock(ptl);
162 pte = *ptep;
163 if (!is_swap_pte(pte))
164 goto out;
165
166 entry = pte_to_swp_entry(pte);
167
168 if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
169 goto out;
170
Christoph Lameter06972122006-06-23 02:03:35 -0700171 get_page(new);
172 pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
173 if (is_write_migration_entry(entry))
174 pte = pte_mkwrite(pte);
175 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);
184 lazy_mmu_prot_update(pte);
185
Christoph Lameter06972122006-06-23 02:03:35 -0700186out:
187 pte_unmap_unlock(ptep, ptl);
188}
189
190/*
Christoph Lameter04e62a22006-06-23 02:03:38 -0700191 * Note that remove_file_migration_ptes will only work on regular mappings,
192 * Nonlinear mappings do not use migration entries.
193 */
194static void remove_file_migration_ptes(struct page *old, struct page *new)
195{
196 struct vm_area_struct *vma;
197 struct address_space *mapping = page_mapping(new);
198 struct prio_tree_iter iter;
199 pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
200
201 if (!mapping)
202 return;
203
204 spin_lock(&mapping->i_mmap_lock);
205
206 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff)
207 remove_migration_pte(vma, old, new);
208
209 spin_unlock(&mapping->i_mmap_lock);
210}
211
212/*
Christoph Lameter06972122006-06-23 02:03:35 -0700213 * Must hold mmap_sem lock on at least one of the vmas containing
214 * the page so that the anon_vma cannot vanish.
215 */
Christoph Lameter04e62a22006-06-23 02:03:38 -0700216static void remove_anon_migration_ptes(struct page *old, struct page *new)
Christoph Lameter06972122006-06-23 02:03:35 -0700217{
218 struct anon_vma *anon_vma;
219 struct vm_area_struct *vma;
220 unsigned long mapping;
221
222 mapping = (unsigned long)new->mapping;
223
224 if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
225 return;
226
227 /*
228 * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
229 */
230 anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
231 spin_lock(&anon_vma->lock);
232
233 list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
Christoph Lameter04e62a22006-06-23 02:03:38 -0700234 remove_migration_pte(vma, old, new);
Christoph Lameter06972122006-06-23 02:03:35 -0700235
236 spin_unlock(&anon_vma->lock);
237}
238
239/*
Christoph Lameter04e62a22006-06-23 02:03:38 -0700240 * Get rid of all migration entries and replace them by
241 * references to the indicated page.
242 */
243static void remove_migration_ptes(struct page *old, struct page *new)
244{
245 if (PageAnon(new))
246 remove_anon_migration_ptes(old, new);
247 else
248 remove_file_migration_ptes(old, new);
249}
250
251/*
Christoph Lameter06972122006-06-23 02:03:35 -0700252 * Something used the pte of a page under migration. We need to
253 * get to the page and wait until migration is finished.
254 * When we return from this function the fault will be retried.
255 *
256 * This function is called from do_swap_page().
257 */
258void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
259 unsigned long address)
260{
261 pte_t *ptep, pte;
262 spinlock_t *ptl;
263 swp_entry_t entry;
264 struct page *page;
265
266 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
267 pte = *ptep;
268 if (!is_swap_pte(pte))
269 goto out;
270
271 entry = pte_to_swp_entry(pte);
272 if (!is_migration_entry(entry))
273 goto out;
274
275 page = migration_entry_to_page(entry);
276
277 get_page(page);
278 pte_unmap_unlock(ptep, ptl);
279 wait_on_page_locked(page);
280 put_page(page);
281 return;
282out:
283 pte_unmap_unlock(ptep, ptl);
284}
285
Christoph Lameterb20a3502006-03-22 00:09:12 -0800286/*
Christoph Lameterc3fcf8a2006-06-23 02:03:32 -0700287 * Replace the page in the mapping.
Christoph Lameter5b5c7122006-06-23 02:03:29 -0700288 *
289 * The number of remaining references must be:
290 * 1 for anonymous pages without a mapping
291 * 2 for pages with a mapping
292 * 3 for pages with a mapping and PagePrivate set.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800293 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700294static int migrate_page_move_mapping(struct address_space *mapping,
295 struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800296{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800297 void **pslot;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800298
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700299 if (!mapping) {
300 /* Anonymous page */
301 if (page_count(page) != 1)
302 return -EAGAIN;
303 return 0;
304 }
305
Christoph Lameterb20a3502006-03-22 00:09:12 -0800306 write_lock_irq(&mapping->tree_lock);
307
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800308 pslot = radix_tree_lookup_slot(&mapping->page_tree,
309 page_index(page));
Christoph Lameterb20a3502006-03-22 00:09:12 -0800310
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700311 if (page_count(page) != 2 + !!PagePrivate(page) ||
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800312 (struct page *)radix_tree_deref_slot(pslot) != page) {
Christoph Lameterb20a3502006-03-22 00:09:12 -0800313 write_unlock_irq(&mapping->tree_lock);
Christoph Lametere23ca002006-04-10 22:52:57 -0700314 return -EAGAIN;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800315 }
316
317 /*
318 * Now we know that no one else is looking at the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800319 */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800320 get_page(newpage); /* add cache reference */
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700321#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800322 if (PageSwapCache(page)) {
323 SetPageSwapCache(newpage);
324 set_page_private(newpage, page_private(page));
325 }
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700326#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800327
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800328 radix_tree_replace_slot(pslot, newpage);
329
330 /*
331 * Drop cache reference from old page.
332 * We know this isn't the last reference.
333 */
Christoph Lameterb20a3502006-03-22 00:09:12 -0800334 __put_page(page);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800335
Christoph Lameterb20a3502006-03-22 00:09:12 -0800336 write_unlock_irq(&mapping->tree_lock);
337
338 return 0;
339}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800340
341/*
342 * Copy the page to its new location
343 */
Christoph Lametere7340f72006-06-23 02:03:29 -0700344static void migrate_page_copy(struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800345{
346 copy_highpage(newpage, page);
347
348 if (PageError(page))
349 SetPageError(newpage);
350 if (PageReferenced(page))
351 SetPageReferenced(newpage);
352 if (PageUptodate(page))
353 SetPageUptodate(newpage);
354 if (PageActive(page))
355 SetPageActive(newpage);
356 if (PageChecked(page))
357 SetPageChecked(newpage);
358 if (PageMappedToDisk(page))
359 SetPageMappedToDisk(newpage);
360
361 if (PageDirty(page)) {
362 clear_page_dirty_for_io(page);
363 set_page_dirty(newpage);
364 }
365
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700366#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800367 ClearPageSwapCache(page);
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700368#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800369 ClearPageActive(page);
370 ClearPagePrivate(page);
371 set_page_private(page, 0);
372 page->mapping = NULL;
373
374 /*
375 * If any waiters have accumulated on the new page then
376 * wake them up.
377 */
378 if (PageWriteback(newpage))
379 end_page_writeback(newpage);
380}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800381
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700382/************************************************************
383 * Migration functions
384 ***********************************************************/
385
386/* Always fail migration. Used for mappings that are not movable */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700387int fail_migrate_page(struct address_space *mapping,
388 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700389{
390 return -EIO;
391}
392EXPORT_SYMBOL(fail_migrate_page);
393
Christoph Lameterb20a3502006-03-22 00:09:12 -0800394/*
395 * Common logic to directly migrate a single page suitable for
396 * pages that do not use PagePrivate.
397 *
398 * Pages are locked upon entry and exit.
399 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700400int migrate_page(struct address_space *mapping,
401 struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800402{
403 int rc;
404
405 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
406
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700407 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800408
409 if (rc)
410 return rc;
411
412 migrate_page_copy(newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800413 return 0;
414}
415EXPORT_SYMBOL(migrate_page);
416
David Howells93614012006-09-30 20:45:40 +0200417#ifdef CONFIG_BLOCK
Christoph Lameterb20a3502006-03-22 00:09:12 -0800418/*
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700419 * Migration function for pages with buffers. This function can only be used
420 * if the underlying filesystem guarantees that no other references to "page"
421 * exist.
422 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700423int buffer_migrate_page(struct address_space *mapping,
424 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700425{
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700426 struct buffer_head *bh, *head;
427 int rc;
428
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700429 if (!page_has_buffers(page))
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700430 return migrate_page(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700431
432 head = page_buffers(page);
433
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700434 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700435
436 if (rc)
437 return rc;
438
439 bh = head;
440 do {
441 get_bh(bh);
442 lock_buffer(bh);
443 bh = bh->b_this_page;
444
445 } while (bh != head);
446
447 ClearPagePrivate(page);
448 set_page_private(newpage, page_private(page));
449 set_page_private(page, 0);
450 put_page(page);
451 get_page(newpage);
452
453 bh = head;
454 do {
455 set_bh_page(bh, newpage, bh_offset(bh));
456 bh = bh->b_this_page;
457
458 } while (bh != head);
459
460 SetPagePrivate(newpage);
461
462 migrate_page_copy(newpage, page);
463
464 bh = head;
465 do {
466 unlock_buffer(bh);
467 put_bh(bh);
468 bh = bh->b_this_page;
469
470 } while (bh != head);
471
472 return 0;
473}
474EXPORT_SYMBOL(buffer_migrate_page);
David Howells93614012006-09-30 20:45:40 +0200475#endif
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700476
Christoph Lameter04e62a22006-06-23 02:03:38 -0700477/*
478 * Writeback a page to clean the dirty state
479 */
480static int writeout(struct address_space *mapping, struct page *page)
481{
482 struct writeback_control wbc = {
483 .sync_mode = WB_SYNC_NONE,
484 .nr_to_write = 1,
485 .range_start = 0,
486 .range_end = LLONG_MAX,
487 .nonblocking = 1,
488 .for_reclaim = 1
489 };
490 int rc;
491
492 if (!mapping->a_ops->writepage)
493 /* No write method for the address space */
494 return -EINVAL;
495
496 if (!clear_page_dirty_for_io(page))
497 /* Someone else already triggered a write */
498 return -EAGAIN;
499
500 /*
501 * A dirty page may imply that the underlying filesystem has
502 * the page on some queue. So the page must be clean for
503 * migration. Writeout may mean we loose the lock and the
504 * page state is no longer what we checked for earlier.
505 * At this point we know that the migration attempt cannot
506 * be successful.
507 */
508 remove_migration_ptes(page, page);
509
510 rc = mapping->a_ops->writepage(page, &wbc);
511 if (rc < 0)
512 /* I/O Error writing */
513 return -EIO;
514
515 if (rc != AOP_WRITEPAGE_ACTIVATE)
516 /* unlocked. Relock */
517 lock_page(page);
518
519 return -EAGAIN;
520}
521
522/*
523 * Default handling if a filesystem does not provide a migration function.
524 */
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700525static int fallback_migrate_page(struct address_space *mapping,
526 struct page *newpage, struct page *page)
527{
Christoph Lameter04e62a22006-06-23 02:03:38 -0700528 if (PageDirty(page))
529 return writeout(mapping, page);
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700530
531 /*
532 * Buffers may be managed in a filesystem specific way.
533 * We must have no buffers or drop them.
534 */
David Howellsb398f6b2006-08-29 19:05:58 +0100535 if (PagePrivate(page) &&
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700536 !try_to_release_page(page, GFP_KERNEL))
537 return -EAGAIN;
538
539 return migrate_page(mapping, newpage, page);
540}
541
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700542/*
Christoph Lametere24f0b82006-06-23 02:03:51 -0700543 * Move a page to a newly allocated page
544 * The page is locked and all ptes have been successfully removed.
545 *
546 * The new page will have replaced the old page if this function
547 * is successful.
548 */
549static int move_to_new_page(struct page *newpage, struct page *page)
550{
551 struct address_space *mapping;
552 int rc;
553
554 /*
555 * Block others from accessing the page when we get around to
556 * establishing additional references. We are the only one
557 * holding a reference to the new page at this point.
558 */
559 if (TestSetPageLocked(newpage))
560 BUG();
561
562 /* Prepare mapping for the new page.*/
563 newpage->index = page->index;
564 newpage->mapping = page->mapping;
565
566 mapping = page_mapping(page);
567 if (!mapping)
568 rc = migrate_page(mapping, newpage, page);
569 else if (mapping->a_ops->migratepage)
570 /*
571 * Most pages have a mapping and most filesystems
572 * should provide a migration function. Anonymous
573 * pages are part of swap space which also has its
574 * own migration function. This is the most common
575 * path for page migration.
576 */
577 rc = mapping->a_ops->migratepage(mapping,
578 newpage, page);
579 else
580 rc = fallback_migrate_page(mapping, newpage, page);
581
582 if (!rc)
583 remove_migration_ptes(page, newpage);
584 else
585 newpage->mapping = NULL;
586
587 unlock_page(newpage);
588
589 return rc;
590}
591
592/*
593 * Obtain the lock on page, remove all ptes and migrate the page
594 * to the newly allocated page in newpage.
595 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700596static int unmap_and_move(new_page_t get_new_page, unsigned long private,
597 struct page *page, int force)
Christoph Lametere24f0b82006-06-23 02:03:51 -0700598{
599 int rc = 0;
Christoph Lameter742755a2006-06-23 02:03:55 -0700600 int *result = NULL;
601 struct page *newpage = get_new_page(page, private, &result);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700602
603 if (!newpage)
604 return -ENOMEM;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700605
606 if (page_count(page) == 1)
607 /* page was freed from under us. So we are done. */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700608 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700609
610 rc = -EAGAIN;
611 if (TestSetPageLocked(page)) {
612 if (!force)
Christoph Lameter95a402c2006-06-23 02:03:53 -0700613 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700614 lock_page(page);
615 }
616
617 if (PageWriteback(page)) {
618 if (!force)
619 goto unlock;
620 wait_on_page_writeback(page);
621 }
622
623 /*
624 * Establish migration ptes or remove ptes
625 */
Christoph Lametere6a15302006-06-25 05:46:49 -0700626 try_to_unmap(page, 1);
627 if (!page_mapped(page))
628 rc = move_to_new_page(newpage, page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700629
630 if (rc)
631 remove_migration_ptes(page, page);
Christoph Lametere6a15302006-06-25 05:46:49 -0700632
Christoph Lametere24f0b82006-06-23 02:03:51 -0700633unlock:
634 unlock_page(page);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700635
Christoph Lametere24f0b82006-06-23 02:03:51 -0700636 if (rc != -EAGAIN) {
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700637 /*
638 * A page that has been migrated has all references
639 * removed and will be freed. A page that has not been
640 * migrated will have kepts its references and be
641 * restored.
642 */
643 list_del(&page->lru);
644 move_to_lru(page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700645 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700646
647move_newpage:
648 /*
649 * Move the new page to the LRU. If migration was not successful
650 * then this will free the page.
651 */
652 move_to_lru(newpage);
Christoph Lameter742755a2006-06-23 02:03:55 -0700653 if (result) {
654 if (rc)
655 *result = rc;
656 else
657 *result = page_to_nid(newpage);
658 }
Christoph Lametere24f0b82006-06-23 02:03:51 -0700659 return rc;
660}
661
662/*
Christoph Lameterb20a3502006-03-22 00:09:12 -0800663 * migrate_pages
664 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700665 * The function takes one list of pages to migrate and a function
666 * that determines from the page to be migrated and the private data
667 * the target of the move and allocates the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800668 *
669 * The function returns after 10 attempts or if no pages
670 * are movable anymore because to has become empty
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700671 * or no retryable pages exist anymore. All pages will be
672 * retruned to the LRU or freed.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800673 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700674 * Return: Number of pages not migrated or error code.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800675 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700676int migrate_pages(struct list_head *from,
677 new_page_t get_new_page, unsigned long private)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800678{
Christoph Lametere24f0b82006-06-23 02:03:51 -0700679 int retry = 1;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800680 int nr_failed = 0;
681 int pass = 0;
682 struct page *page;
683 struct page *page2;
684 int swapwrite = current->flags & PF_SWAPWRITE;
685 int rc;
686
687 if (!swapwrite)
688 current->flags |= PF_SWAPWRITE;
689
Christoph Lametere24f0b82006-06-23 02:03:51 -0700690 for(pass = 0; pass < 10 && retry; pass++) {
691 retry = 0;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800692
Christoph Lametere24f0b82006-06-23 02:03:51 -0700693 list_for_each_entry_safe(page, page2, from, lru) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700694 cond_resched();
Christoph Lameterb20a3502006-03-22 00:09:12 -0800695
Christoph Lameter95a402c2006-06-23 02:03:53 -0700696 rc = unmap_and_move(get_new_page, private,
697 page, pass > 2);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800698
Christoph Lametere24f0b82006-06-23 02:03:51 -0700699 switch(rc) {
Christoph Lameter95a402c2006-06-23 02:03:53 -0700700 case -ENOMEM:
701 goto out;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700702 case -EAGAIN:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700703 retry++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700704 break;
705 case 0:
Christoph Lametere24f0b82006-06-23 02:03:51 -0700706 break;
707 default:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700708 /* Permanent failure */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700709 nr_failed++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700710 break;
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700711 }
Christoph Lameterb20a3502006-03-22 00:09:12 -0800712 }
713 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700714 rc = 0;
715out:
Christoph Lameterb20a3502006-03-22 00:09:12 -0800716 if (!swapwrite)
717 current->flags &= ~PF_SWAPWRITE;
718
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700719 putback_lru_pages(from);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700720
721 if (rc)
722 return rc;
723
Christoph Lameterb20a3502006-03-22 00:09:12 -0800724 return nr_failed + retry;
725}
726
Christoph Lameter742755a2006-06-23 02:03:55 -0700727#ifdef CONFIG_NUMA
728/*
729 * Move a list of individual pages
730 */
731struct page_to_node {
732 unsigned long addr;
733 struct page *page;
734 int node;
735 int status;
736};
737
738static struct page *new_page_node(struct page *p, unsigned long private,
739 int **result)
740{
741 struct page_to_node *pm = (struct page_to_node *)private;
742
743 while (pm->node != MAX_NUMNODES && pm->page != p)
744 pm++;
745
746 if (pm->node == MAX_NUMNODES)
747 return NULL;
748
749 *result = &pm->status;
750
Christoph Lameter980128f2006-09-25 23:31:46 -0700751 return alloc_pages_node(pm->node, GFP_HIGHUSER | GFP_THISNODE, 0);
Christoph Lameter742755a2006-06-23 02:03:55 -0700752}
753
754/*
755 * Move a set of pages as indicated in the pm array. The addr
756 * field must be set to the virtual address of the page to be moved
757 * and the node number must contain a valid target node.
758 */
759static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
760 int migrate_all)
761{
762 int err;
763 struct page_to_node *pp;
764 LIST_HEAD(pagelist);
765
766 down_read(&mm->mmap_sem);
767
768 /*
769 * Build a list of pages to migrate
770 */
771 migrate_prep();
772 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
773 struct vm_area_struct *vma;
774 struct page *page;
775
776 /*
777 * A valid page pointer that will not match any of the
778 * pages that will be moved.
779 */
780 pp->page = ZERO_PAGE(0);
781
782 err = -EFAULT;
783 vma = find_vma(mm, pp->addr);
Christoph Lameter0dc952d2007-03-05 00:30:33 -0800784 if (!vma || !vma_migratable(vma))
Christoph Lameter742755a2006-06-23 02:03:55 -0700785 goto set_status;
786
787 page = follow_page(vma, pp->addr, FOLL_GET);
788 err = -ENOENT;
789 if (!page)
790 goto set_status;
791
792 if (PageReserved(page)) /* Check for zero page */
793 goto put_and_set;
794
795 pp->page = page;
796 err = page_to_nid(page);
797
798 if (err == pp->node)
799 /*
800 * Node already in the right place
801 */
802 goto put_and_set;
803
804 err = -EACCES;
805 if (page_mapcount(page) > 1 &&
806 !migrate_all)
807 goto put_and_set;
808
809 err = isolate_lru_page(page, &pagelist);
810put_and_set:
811 /*
812 * Either remove the duplicate refcount from
813 * isolate_lru_page() or drop the page ref if it was
814 * not isolated.
815 */
816 put_page(page);
817set_status:
818 pp->status = err;
819 }
820
821 if (!list_empty(&pagelist))
822 err = migrate_pages(&pagelist, new_page_node,
823 (unsigned long)pm);
824 else
825 err = -ENOENT;
826
827 up_read(&mm->mmap_sem);
828 return err;
829}
830
831/*
832 * Determine the nodes of a list of pages. The addr in the pm array
833 * must have been set to the virtual address of which we want to determine
834 * the node number.
835 */
836static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
837{
838 down_read(&mm->mmap_sem);
839
840 for ( ; pm->node != MAX_NUMNODES; pm++) {
841 struct vm_area_struct *vma;
842 struct page *page;
843 int err;
844
845 err = -EFAULT;
846 vma = find_vma(mm, pm->addr);
847 if (!vma)
848 goto set_status;
849
850 page = follow_page(vma, pm->addr, 0);
851 err = -ENOENT;
852 /* Use PageReserved to check for zero page */
853 if (!page || PageReserved(page))
854 goto set_status;
855
856 err = page_to_nid(page);
857set_status:
858 pm->status = err;
859 }
860
861 up_read(&mm->mmap_sem);
862 return 0;
863}
864
865/*
866 * Move a list of pages in the address space of the currently executing
867 * process.
868 */
869asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages,
870 const void __user * __user *pages,
871 const int __user *nodes,
872 int __user *status, int flags)
873{
874 int err = 0;
875 int i;
876 struct task_struct *task;
877 nodemask_t task_nodes;
878 struct mm_struct *mm;
879 struct page_to_node *pm = NULL;
880
881 /* Check flags */
882 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
883 return -EINVAL;
884
885 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
886 return -EPERM;
887
888 /* Find the mm_struct */
889 read_lock(&tasklist_lock);
890 task = pid ? find_task_by_pid(pid) : current;
891 if (!task) {
892 read_unlock(&tasklist_lock);
893 return -ESRCH;
894 }
895 mm = get_task_mm(task);
896 read_unlock(&tasklist_lock);
897
898 if (!mm)
899 return -EINVAL;
900
901 /*
902 * Check if this process has the right to modify the specified
903 * process. The right exists if the process has administrative
904 * capabilities, superuser privileges or the same
905 * userid as the target process.
906 */
907 if ((current->euid != task->suid) && (current->euid != task->uid) &&
908 (current->uid != task->suid) && (current->uid != task->uid) &&
909 !capable(CAP_SYS_NICE)) {
910 err = -EPERM;
911 goto out2;
912 }
913
David Quigley86c3a762006-06-23 02:04:02 -0700914 err = security_task_movememory(task);
915 if (err)
916 goto out2;
917
918
Christoph Lameter742755a2006-06-23 02:03:55 -0700919 task_nodes = cpuset_mems_allowed(task);
920
921 /* Limit nr_pages so that the multiplication may not overflow */
922 if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) {
923 err = -E2BIG;
924 goto out2;
925 }
926
927 pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node));
928 if (!pm) {
929 err = -ENOMEM;
930 goto out2;
931 }
932
933 /*
934 * Get parameters from user space and initialize the pm
935 * array. Return various errors if the user did something wrong.
936 */
937 for (i = 0; i < nr_pages; i++) {
938 const void *p;
939
940 err = -EFAULT;
941 if (get_user(p, pages + i))
942 goto out;
943
944 pm[i].addr = (unsigned long)p;
945 if (nodes) {
946 int node;
947
948 if (get_user(node, nodes + i))
949 goto out;
950
951 err = -ENODEV;
952 if (!node_online(node))
953 goto out;
954
955 err = -EACCES;
956 if (!node_isset(node, task_nodes))
957 goto out;
958
959 pm[i].node = node;
Stephen Rothwell8ce08462006-11-02 22:07:28 -0800960 } else
961 pm[i].node = 0; /* anything to not match MAX_NUMNODES */
Christoph Lameter742755a2006-06-23 02:03:55 -0700962 }
963 /* End marker */
964 pm[nr_pages].node = MAX_NUMNODES;
965
966 if (nodes)
967 err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL);
968 else
969 err = do_pages_stat(mm, pm);
970
971 if (err >= 0)
972 /* Return status information */
973 for (i = 0; i < nr_pages; i++)
974 if (put_user(pm[i].status, status + i))
975 err = -EFAULT;
976
977out:
978 vfree(pm);
979out2:
980 mmput(mm);
981 return err;
982}
983#endif
984
Christoph Lameter7b2259b2006-06-25 05:46:48 -0700985/*
986 * Call migration functions in the vma_ops that may prepare
987 * memory in a vm for migration. migration functions may perform
988 * the migration for vmas that do not have an underlying page struct.
989 */
990int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
991 const nodemask_t *from, unsigned long flags)
992{
993 struct vm_area_struct *vma;
994 int err = 0;
995
996 for(vma = mm->mmap; vma->vm_next && !err; vma = vma->vm_next) {
997 if (vma->vm_ops && vma->vm_ops->migrate) {
998 err = vma->vm_ops->migrate(vma, to, from, flags);
999 if (err)
1000 break;
1001 }
1002 }
1003 return err;
1004}