blob: b4979d423d2be5b7885f4cd7e24f45bdf7aa27ca [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{
Christoph Lameterb20a3502006-03-22 00:09:12 -0800297 struct page **radix_pointer;
298
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
308 radix_pointer = (struct page **)radix_tree_lookup_slot(
309 &mapping->page_tree,
310 page_index(page));
311
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700312 if (page_count(page) != 2 + !!PagePrivate(page) ||
Christoph Lameterb20a3502006-03-22 00:09:12 -0800313 *radix_pointer != page) {
314 write_unlock_irq(&mapping->tree_lock);
Christoph Lametere23ca002006-04-10 22:52:57 -0700315 return -EAGAIN;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800316 }
317
318 /*
319 * Now we know that no one else is looking at the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800320 */
321 get_page(newpage);
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700322#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800323 if (PageSwapCache(page)) {
324 SetPageSwapCache(newpage);
325 set_page_private(newpage, page_private(page));
326 }
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700327#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800328
329 *radix_pointer = newpage;
330 __put_page(page);
331 write_unlock_irq(&mapping->tree_lock);
332
333 return 0;
334}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800335
336/*
337 * Copy the page to its new location
338 */
Christoph Lametere7340f72006-06-23 02:03:29 -0700339static void migrate_page_copy(struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800340{
341 copy_highpage(newpage, page);
342
343 if (PageError(page))
344 SetPageError(newpage);
345 if (PageReferenced(page))
346 SetPageReferenced(newpage);
347 if (PageUptodate(page))
348 SetPageUptodate(newpage);
349 if (PageActive(page))
350 SetPageActive(newpage);
351 if (PageChecked(page))
352 SetPageChecked(newpage);
353 if (PageMappedToDisk(page))
354 SetPageMappedToDisk(newpage);
355
356 if (PageDirty(page)) {
357 clear_page_dirty_for_io(page);
358 set_page_dirty(newpage);
359 }
360
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700361#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800362 ClearPageSwapCache(page);
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700363#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800364 ClearPageActive(page);
365 ClearPagePrivate(page);
366 set_page_private(page, 0);
367 page->mapping = NULL;
368
369 /*
370 * If any waiters have accumulated on the new page then
371 * wake them up.
372 */
373 if (PageWriteback(newpage))
374 end_page_writeback(newpage);
375}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800376
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700377/************************************************************
378 * Migration functions
379 ***********************************************************/
380
381/* Always fail migration. Used for mappings that are not movable */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700382int fail_migrate_page(struct address_space *mapping,
383 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700384{
385 return -EIO;
386}
387EXPORT_SYMBOL(fail_migrate_page);
388
Christoph Lameterb20a3502006-03-22 00:09:12 -0800389/*
390 * Common logic to directly migrate a single page suitable for
391 * pages that do not use PagePrivate.
392 *
393 * Pages are locked upon entry and exit.
394 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700395int migrate_page(struct address_space *mapping,
396 struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800397{
398 int rc;
399
400 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
401
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700402 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800403
404 if (rc)
405 return rc;
406
407 migrate_page_copy(newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800408 return 0;
409}
410EXPORT_SYMBOL(migrate_page);
411
David Howells93614012006-09-30 20:45:40 +0200412#ifdef CONFIG_BLOCK
Christoph Lameterb20a3502006-03-22 00:09:12 -0800413/*
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700414 * Migration function for pages with buffers. This function can only be used
415 * if the underlying filesystem guarantees that no other references to "page"
416 * exist.
417 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700418int buffer_migrate_page(struct address_space *mapping,
419 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700420{
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700421 struct buffer_head *bh, *head;
422 int rc;
423
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700424 if (!page_has_buffers(page))
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700425 return migrate_page(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700426
427 head = page_buffers(page);
428
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700429 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700430
431 if (rc)
432 return rc;
433
434 bh = head;
435 do {
436 get_bh(bh);
437 lock_buffer(bh);
438 bh = bh->b_this_page;
439
440 } while (bh != head);
441
442 ClearPagePrivate(page);
443 set_page_private(newpage, page_private(page));
444 set_page_private(page, 0);
445 put_page(page);
446 get_page(newpage);
447
448 bh = head;
449 do {
450 set_bh_page(bh, newpage, bh_offset(bh));
451 bh = bh->b_this_page;
452
453 } while (bh != head);
454
455 SetPagePrivate(newpage);
456
457 migrate_page_copy(newpage, page);
458
459 bh = head;
460 do {
461 unlock_buffer(bh);
462 put_bh(bh);
463 bh = bh->b_this_page;
464
465 } while (bh != head);
466
467 return 0;
468}
469EXPORT_SYMBOL(buffer_migrate_page);
David Howells93614012006-09-30 20:45:40 +0200470#endif
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700471
Christoph Lameter04e62a22006-06-23 02:03:38 -0700472/*
473 * Writeback a page to clean the dirty state
474 */
475static int writeout(struct address_space *mapping, struct page *page)
476{
477 struct writeback_control wbc = {
478 .sync_mode = WB_SYNC_NONE,
479 .nr_to_write = 1,
480 .range_start = 0,
481 .range_end = LLONG_MAX,
482 .nonblocking = 1,
483 .for_reclaim = 1
484 };
485 int rc;
486
487 if (!mapping->a_ops->writepage)
488 /* No write method for the address space */
489 return -EINVAL;
490
491 if (!clear_page_dirty_for_io(page))
492 /* Someone else already triggered a write */
493 return -EAGAIN;
494
495 /*
496 * A dirty page may imply that the underlying filesystem has
497 * the page on some queue. So the page must be clean for
498 * migration. Writeout may mean we loose the lock and the
499 * page state is no longer what we checked for earlier.
500 * At this point we know that the migration attempt cannot
501 * be successful.
502 */
503 remove_migration_ptes(page, page);
504
505 rc = mapping->a_ops->writepage(page, &wbc);
506 if (rc < 0)
507 /* I/O Error writing */
508 return -EIO;
509
510 if (rc != AOP_WRITEPAGE_ACTIVATE)
511 /* unlocked. Relock */
512 lock_page(page);
513
514 return -EAGAIN;
515}
516
517/*
518 * Default handling if a filesystem does not provide a migration function.
519 */
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700520static int fallback_migrate_page(struct address_space *mapping,
521 struct page *newpage, struct page *page)
522{
Christoph Lameter04e62a22006-06-23 02:03:38 -0700523 if (PageDirty(page))
524 return writeout(mapping, page);
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700525
526 /*
527 * Buffers may be managed in a filesystem specific way.
528 * We must have no buffers or drop them.
529 */
David Howellsb398f6b2006-08-29 19:05:58 +0100530 if (PagePrivate(page) &&
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700531 !try_to_release_page(page, GFP_KERNEL))
532 return -EAGAIN;
533
534 return migrate_page(mapping, newpage, page);
535}
536
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700537/*
Christoph Lametere24f0b82006-06-23 02:03:51 -0700538 * Move a page to a newly allocated page
539 * The page is locked and all ptes have been successfully removed.
540 *
541 * The new page will have replaced the old page if this function
542 * is successful.
543 */
544static int move_to_new_page(struct page *newpage, struct page *page)
545{
546 struct address_space *mapping;
547 int rc;
548
549 /*
550 * Block others from accessing the page when we get around to
551 * establishing additional references. We are the only one
552 * holding a reference to the new page at this point.
553 */
554 if (TestSetPageLocked(newpage))
555 BUG();
556
557 /* Prepare mapping for the new page.*/
558 newpage->index = page->index;
559 newpage->mapping = page->mapping;
560
561 mapping = page_mapping(page);
562 if (!mapping)
563 rc = migrate_page(mapping, newpage, page);
564 else if (mapping->a_ops->migratepage)
565 /*
566 * Most pages have a mapping and most filesystems
567 * should provide a migration function. Anonymous
568 * pages are part of swap space which also has its
569 * own migration function. This is the most common
570 * path for page migration.
571 */
572 rc = mapping->a_ops->migratepage(mapping,
573 newpage, page);
574 else
575 rc = fallback_migrate_page(mapping, newpage, page);
576
577 if (!rc)
578 remove_migration_ptes(page, newpage);
579 else
580 newpage->mapping = NULL;
581
582 unlock_page(newpage);
583
584 return rc;
585}
586
587/*
588 * Obtain the lock on page, remove all ptes and migrate the page
589 * to the newly allocated page in newpage.
590 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700591static int unmap_and_move(new_page_t get_new_page, unsigned long private,
592 struct page *page, int force)
Christoph Lametere24f0b82006-06-23 02:03:51 -0700593{
594 int rc = 0;
Christoph Lameter742755a2006-06-23 02:03:55 -0700595 int *result = NULL;
596 struct page *newpage = get_new_page(page, private, &result);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700597
598 if (!newpage)
599 return -ENOMEM;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700600
601 if (page_count(page) == 1)
602 /* page was freed from under us. So we are done. */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700603 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700604
605 rc = -EAGAIN;
606 if (TestSetPageLocked(page)) {
607 if (!force)
Christoph Lameter95a402c2006-06-23 02:03:53 -0700608 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700609 lock_page(page);
610 }
611
612 if (PageWriteback(page)) {
613 if (!force)
614 goto unlock;
615 wait_on_page_writeback(page);
616 }
617
618 /*
619 * Establish migration ptes or remove ptes
620 */
Christoph Lametere6a15302006-06-25 05:46:49 -0700621 try_to_unmap(page, 1);
622 if (!page_mapped(page))
623 rc = move_to_new_page(newpage, page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700624
625 if (rc)
626 remove_migration_ptes(page, page);
Christoph Lametere6a15302006-06-25 05:46:49 -0700627
Christoph Lametere24f0b82006-06-23 02:03:51 -0700628unlock:
629 unlock_page(page);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700630
Christoph Lametere24f0b82006-06-23 02:03:51 -0700631 if (rc != -EAGAIN) {
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700632 /*
633 * A page that has been migrated has all references
634 * removed and will be freed. A page that has not been
635 * migrated will have kepts its references and be
636 * restored.
637 */
638 list_del(&page->lru);
639 move_to_lru(page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700640 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700641
642move_newpage:
643 /*
644 * Move the new page to the LRU. If migration was not successful
645 * then this will free the page.
646 */
647 move_to_lru(newpage);
Christoph Lameter742755a2006-06-23 02:03:55 -0700648 if (result) {
649 if (rc)
650 *result = rc;
651 else
652 *result = page_to_nid(newpage);
653 }
Christoph Lametere24f0b82006-06-23 02:03:51 -0700654 return rc;
655}
656
657/*
Christoph Lameterb20a3502006-03-22 00:09:12 -0800658 * migrate_pages
659 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700660 * The function takes one list of pages to migrate and a function
661 * that determines from the page to be migrated and the private data
662 * the target of the move and allocates the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800663 *
664 * The function returns after 10 attempts or if no pages
665 * are movable anymore because to has become empty
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700666 * or no retryable pages exist anymore. All pages will be
667 * retruned to the LRU or freed.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800668 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700669 * Return: Number of pages not migrated or error code.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800670 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700671int migrate_pages(struct list_head *from,
672 new_page_t get_new_page, unsigned long private)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800673{
Christoph Lametere24f0b82006-06-23 02:03:51 -0700674 int retry = 1;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800675 int nr_failed = 0;
676 int pass = 0;
677 struct page *page;
678 struct page *page2;
679 int swapwrite = current->flags & PF_SWAPWRITE;
680 int rc;
681
682 if (!swapwrite)
683 current->flags |= PF_SWAPWRITE;
684
Christoph Lametere24f0b82006-06-23 02:03:51 -0700685 for(pass = 0; pass < 10 && retry; pass++) {
686 retry = 0;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800687
Christoph Lametere24f0b82006-06-23 02:03:51 -0700688 list_for_each_entry_safe(page, page2, from, lru) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700689 cond_resched();
Christoph Lameterb20a3502006-03-22 00:09:12 -0800690
Christoph Lameter95a402c2006-06-23 02:03:53 -0700691 rc = unmap_and_move(get_new_page, private,
692 page, pass > 2);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800693
Christoph Lametere24f0b82006-06-23 02:03:51 -0700694 switch(rc) {
Christoph Lameter95a402c2006-06-23 02:03:53 -0700695 case -ENOMEM:
696 goto out;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700697 case -EAGAIN:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700698 retry++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700699 break;
700 case 0:
Christoph Lametere24f0b82006-06-23 02:03:51 -0700701 break;
702 default:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700703 /* Permanent failure */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700704 nr_failed++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700705 break;
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700706 }
Christoph Lameterb20a3502006-03-22 00:09:12 -0800707 }
708 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700709 rc = 0;
710out:
Christoph Lameterb20a3502006-03-22 00:09:12 -0800711 if (!swapwrite)
712 current->flags &= ~PF_SWAPWRITE;
713
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700714 putback_lru_pages(from);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700715
716 if (rc)
717 return rc;
718
Christoph Lameterb20a3502006-03-22 00:09:12 -0800719 return nr_failed + retry;
720}
721
Christoph Lameter742755a2006-06-23 02:03:55 -0700722#ifdef CONFIG_NUMA
723/*
724 * Move a list of individual pages
725 */
726struct page_to_node {
727 unsigned long addr;
728 struct page *page;
729 int node;
730 int status;
731};
732
733static struct page *new_page_node(struct page *p, unsigned long private,
734 int **result)
735{
736 struct page_to_node *pm = (struct page_to_node *)private;
737
738 while (pm->node != MAX_NUMNODES && pm->page != p)
739 pm++;
740
741 if (pm->node == MAX_NUMNODES)
742 return NULL;
743
744 *result = &pm->status;
745
Christoph Lameter980128f2006-09-25 23:31:46 -0700746 return alloc_pages_node(pm->node, GFP_HIGHUSER | GFP_THISNODE, 0);
Christoph Lameter742755a2006-06-23 02:03:55 -0700747}
748
749/*
750 * Move a set of pages as indicated in the pm array. The addr
751 * field must be set to the virtual address of the page to be moved
752 * and the node number must contain a valid target node.
753 */
754static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
755 int migrate_all)
756{
757 int err;
758 struct page_to_node *pp;
759 LIST_HEAD(pagelist);
760
761 down_read(&mm->mmap_sem);
762
763 /*
764 * Build a list of pages to migrate
765 */
766 migrate_prep();
767 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
768 struct vm_area_struct *vma;
769 struct page *page;
770
771 /*
772 * A valid page pointer that will not match any of the
773 * pages that will be moved.
774 */
775 pp->page = ZERO_PAGE(0);
776
777 err = -EFAULT;
778 vma = find_vma(mm, pp->addr);
779 if (!vma)
780 goto set_status;
781
782 page = follow_page(vma, pp->addr, FOLL_GET);
783 err = -ENOENT;
784 if (!page)
785 goto set_status;
786
787 if (PageReserved(page)) /* Check for zero page */
788 goto put_and_set;
789
790 pp->page = page;
791 err = page_to_nid(page);
792
793 if (err == pp->node)
794 /*
795 * Node already in the right place
796 */
797 goto put_and_set;
798
799 err = -EACCES;
800 if (page_mapcount(page) > 1 &&
801 !migrate_all)
802 goto put_and_set;
803
804 err = isolate_lru_page(page, &pagelist);
805put_and_set:
806 /*
807 * Either remove the duplicate refcount from
808 * isolate_lru_page() or drop the page ref if it was
809 * not isolated.
810 */
811 put_page(page);
812set_status:
813 pp->status = err;
814 }
815
816 if (!list_empty(&pagelist))
817 err = migrate_pages(&pagelist, new_page_node,
818 (unsigned long)pm);
819 else
820 err = -ENOENT;
821
822 up_read(&mm->mmap_sem);
823 return err;
824}
825
826/*
827 * Determine the nodes of a list of pages. The addr in the pm array
828 * must have been set to the virtual address of which we want to determine
829 * the node number.
830 */
831static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
832{
833 down_read(&mm->mmap_sem);
834
835 for ( ; pm->node != MAX_NUMNODES; pm++) {
836 struct vm_area_struct *vma;
837 struct page *page;
838 int err;
839
840 err = -EFAULT;
841 vma = find_vma(mm, pm->addr);
842 if (!vma)
843 goto set_status;
844
845 page = follow_page(vma, pm->addr, 0);
846 err = -ENOENT;
847 /* Use PageReserved to check for zero page */
848 if (!page || PageReserved(page))
849 goto set_status;
850
851 err = page_to_nid(page);
852set_status:
853 pm->status = err;
854 }
855
856 up_read(&mm->mmap_sem);
857 return 0;
858}
859
860/*
861 * Move a list of pages in the address space of the currently executing
862 * process.
863 */
864asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages,
865 const void __user * __user *pages,
866 const int __user *nodes,
867 int __user *status, int flags)
868{
869 int err = 0;
870 int i;
871 struct task_struct *task;
872 nodemask_t task_nodes;
873 struct mm_struct *mm;
874 struct page_to_node *pm = NULL;
875
876 /* Check flags */
877 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
878 return -EINVAL;
879
880 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
881 return -EPERM;
882
883 /* Find the mm_struct */
884 read_lock(&tasklist_lock);
885 task = pid ? find_task_by_pid(pid) : current;
886 if (!task) {
887 read_unlock(&tasklist_lock);
888 return -ESRCH;
889 }
890 mm = get_task_mm(task);
891 read_unlock(&tasklist_lock);
892
893 if (!mm)
894 return -EINVAL;
895
896 /*
897 * Check if this process has the right to modify the specified
898 * process. The right exists if the process has administrative
899 * capabilities, superuser privileges or the same
900 * userid as the target process.
901 */
902 if ((current->euid != task->suid) && (current->euid != task->uid) &&
903 (current->uid != task->suid) && (current->uid != task->uid) &&
904 !capable(CAP_SYS_NICE)) {
905 err = -EPERM;
906 goto out2;
907 }
908
David Quigley86c3a762006-06-23 02:04:02 -0700909 err = security_task_movememory(task);
910 if (err)
911 goto out2;
912
913
Christoph Lameter742755a2006-06-23 02:03:55 -0700914 task_nodes = cpuset_mems_allowed(task);
915
916 /* Limit nr_pages so that the multiplication may not overflow */
917 if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) {
918 err = -E2BIG;
919 goto out2;
920 }
921
922 pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node));
923 if (!pm) {
924 err = -ENOMEM;
925 goto out2;
926 }
927
928 /*
929 * Get parameters from user space and initialize the pm
930 * array. Return various errors if the user did something wrong.
931 */
932 for (i = 0; i < nr_pages; i++) {
933 const void *p;
934
935 err = -EFAULT;
936 if (get_user(p, pages + i))
937 goto out;
938
939 pm[i].addr = (unsigned long)p;
940 if (nodes) {
941 int node;
942
943 if (get_user(node, nodes + i))
944 goto out;
945
946 err = -ENODEV;
947 if (!node_online(node))
948 goto out;
949
950 err = -EACCES;
951 if (!node_isset(node, task_nodes))
952 goto out;
953
954 pm[i].node = node;
Stephen Rothwell8ce08462006-11-02 22:07:28 -0800955 } else
956 pm[i].node = 0; /* anything to not match MAX_NUMNODES */
Christoph Lameter742755a2006-06-23 02:03:55 -0700957 }
958 /* End marker */
959 pm[nr_pages].node = MAX_NUMNODES;
960
961 if (nodes)
962 err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL);
963 else
964 err = do_pages_stat(mm, pm);
965
966 if (err >= 0)
967 /* Return status information */
968 for (i = 0; i < nr_pages; i++)
969 if (put_user(pm[i].status, status + i))
970 err = -EFAULT;
971
972out:
973 vfree(pm);
974out2:
975 mmput(mm);
976 return err;
977}
978#endif
979
Christoph Lameter7b2259b2006-06-25 05:46:48 -0700980/*
981 * Call migration functions in the vma_ops that may prepare
982 * memory in a vm for migration. migration functions may perform
983 * the migration for vmas that do not have an underlying page struct.
984 */
985int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
986 const nodemask_t *from, unsigned long flags)
987{
988 struct vm_area_struct *vma;
989 int err = 0;
990
991 for(vma = mm->mmap; vma->vm_next && !err; vma = vma->vm_next) {
992 if (vma->vm_ops && vma->vm_ops->migrate) {
993 err = vma->vm_ops->migrate(vma, to, from, flags);
994 if (err)
995 break;
996 }
997 }
998 return err;
999}