blob: 857a987e36904a5850a4d663c6d9e41e494ffe1f [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>
Pavel Emelyanovb4888932007-10-18 23:40:14 -070022#include <linux/nsproxy.h>
Christoph Lameterb20a3502006-03-22 00:09:12 -080023#include <linux/pagevec.h>
24#include <linux/rmap.h>
25#include <linux/topology.h>
26#include <linux/cpu.h>
27#include <linux/cpuset.h>
Christoph Lameter04e62a22006-06-23 02:03:38 -070028#include <linux/writeback.h>
Christoph Lameter742755a2006-06-23 02:03:55 -070029#include <linux/mempolicy.h>
30#include <linux/vmalloc.h>
David Quigley86c3a762006-06-23 02:04:02 -070031#include <linux/security.h>
Christoph Lameterb20a3502006-03-22 00:09:12 -080032
33#include "internal.h"
34
Christoph Lameterb20a3502006-03-22 00:09:12 -080035#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
36
37/*
38 * Isolate one page from the LRU lists. If successful put it onto
39 * the indicated list with elevated page count.
40 *
41 * Result:
42 * -EBUSY: page not on LRU list
43 * 0: page removed from LRU list and added to the specified list.
44 */
45int isolate_lru_page(struct page *page, struct list_head *pagelist)
46{
47 int ret = -EBUSY;
48
49 if (PageLRU(page)) {
50 struct zone *zone = page_zone(page);
51
52 spin_lock_irq(&zone->lru_lock);
KAMEZAWA Hiroyuki3dd9fe82007-07-26 10:41:08 -070053 if (PageLRU(page) && get_page_unless_zero(page)) {
Christoph Lameterb20a3502006-03-22 00:09:12 -080054 ret = 0;
Christoph Lameterb20a3502006-03-22 00:09:12 -080055 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 -0700118/*
119 * Restore a potential migration pte to a working pte entry
120 */
Christoph Lameter04e62a22006-06-23 02:03:38 -0700121static void remove_migration_pte(struct vm_area_struct *vma,
Christoph Lameter06972122006-06-23 02:03:35 -0700122 struct page *old, struct page *new)
123{
124 struct mm_struct *mm = vma->vm_mm;
125 swp_entry_t entry;
126 pgd_t *pgd;
127 pud_t *pud;
128 pmd_t *pmd;
129 pte_t *ptep, pte;
130 spinlock_t *ptl;
Christoph Lameter04e62a22006-06-23 02:03:38 -0700131 unsigned long addr = page_address_in_vma(new, vma);
132
133 if (addr == -EFAULT)
134 return;
Christoph Lameter06972122006-06-23 02:03:35 -0700135
136 pgd = pgd_offset(mm, addr);
137 if (!pgd_present(*pgd))
138 return;
139
140 pud = pud_offset(pgd, addr);
141 if (!pud_present(*pud))
142 return;
143
144 pmd = pmd_offset(pud, addr);
145 if (!pmd_present(*pmd))
146 return;
147
148 ptep = pte_offset_map(pmd, addr);
149
150 if (!is_swap_pte(*ptep)) {
151 pte_unmap(ptep);
152 return;
153 }
154
155 ptl = pte_lockptr(mm, pmd);
156 spin_lock(ptl);
157 pte = *ptep;
158 if (!is_swap_pte(pte))
159 goto out;
160
161 entry = pte_to_swp_entry(pte);
162
163 if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
164 goto out;
165
Christoph Lameter06972122006-06-23 02:03:35 -0700166 get_page(new);
167 pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
168 if (is_write_migration_entry(entry))
169 pte = pte_mkwrite(pte);
KAMEZAWA Hiroyuki97ee0522007-10-16 01:25:43 -0700170 flush_cache_page(vma, addr, pte_pfn(pte));
Christoph Lameter06972122006-06-23 02:03:35 -0700171 set_pte_at(mm, addr, ptep, pte);
Christoph Lameter04e62a22006-06-23 02:03:38 -0700172
173 if (PageAnon(new))
174 page_add_anon_rmap(new, vma, addr);
175 else
176 page_add_file_rmap(new);
177
178 /* No need to invalidate - it was non-present before */
179 update_mmu_cache(vma, addr, pte);
Christoph Lameter04e62a22006-06-23 02:03:38 -0700180
Christoph Lameter06972122006-06-23 02:03:35 -0700181out:
182 pte_unmap_unlock(ptep, ptl);
183}
184
185/*
Christoph Lameter04e62a22006-06-23 02:03:38 -0700186 * Note that remove_file_migration_ptes will only work on regular mappings,
187 * Nonlinear mappings do not use migration entries.
188 */
189static void remove_file_migration_ptes(struct page *old, struct page *new)
190{
191 struct vm_area_struct *vma;
192 struct address_space *mapping = page_mapping(new);
193 struct prio_tree_iter iter;
194 pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
195
196 if (!mapping)
197 return;
198
199 spin_lock(&mapping->i_mmap_lock);
200
201 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff)
202 remove_migration_pte(vma, old, new);
203
204 spin_unlock(&mapping->i_mmap_lock);
205}
206
207/*
Christoph Lameter06972122006-06-23 02:03:35 -0700208 * Must hold mmap_sem lock on at least one of the vmas containing
209 * the page so that the anon_vma cannot vanish.
210 */
Christoph Lameter04e62a22006-06-23 02:03:38 -0700211static void remove_anon_migration_ptes(struct page *old, struct page *new)
Christoph Lameter06972122006-06-23 02:03:35 -0700212{
213 struct anon_vma *anon_vma;
214 struct vm_area_struct *vma;
215 unsigned long mapping;
216
217 mapping = (unsigned long)new->mapping;
218
219 if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
220 return;
221
222 /*
223 * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
224 */
225 anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
226 spin_lock(&anon_vma->lock);
227
228 list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
Christoph Lameter04e62a22006-06-23 02:03:38 -0700229 remove_migration_pte(vma, old, new);
Christoph Lameter06972122006-06-23 02:03:35 -0700230
231 spin_unlock(&anon_vma->lock);
232}
233
234/*
Christoph Lameter04e62a22006-06-23 02:03:38 -0700235 * Get rid of all migration entries and replace them by
236 * references to the indicated page.
237 */
238static void remove_migration_ptes(struct page *old, struct page *new)
239{
240 if (PageAnon(new))
241 remove_anon_migration_ptes(old, new);
242 else
243 remove_file_migration_ptes(old, new);
244}
245
246/*
Christoph Lameter06972122006-06-23 02:03:35 -0700247 * Something used the pte of a page under migration. We need to
248 * get to the page and wait until migration is finished.
249 * When we return from this function the fault will be retried.
250 *
251 * This function is called from do_swap_page().
252 */
253void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
254 unsigned long address)
255{
256 pte_t *ptep, pte;
257 spinlock_t *ptl;
258 swp_entry_t entry;
259 struct page *page;
260
261 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
262 pte = *ptep;
263 if (!is_swap_pte(pte))
264 goto out;
265
266 entry = pte_to_swp_entry(pte);
267 if (!is_migration_entry(entry))
268 goto out;
269
270 page = migration_entry_to_page(entry);
271
272 get_page(page);
273 pte_unmap_unlock(ptep, ptl);
274 wait_on_page_locked(page);
275 put_page(page);
276 return;
277out:
278 pte_unmap_unlock(ptep, ptl);
279}
280
Christoph Lameterb20a3502006-03-22 00:09:12 -0800281/*
Christoph Lameterc3fcf8a2006-06-23 02:03:32 -0700282 * Replace the page in the mapping.
Christoph Lameter5b5c7122006-06-23 02:03:29 -0700283 *
284 * The number of remaining references must be:
285 * 1 for anonymous pages without a mapping
286 * 2 for pages with a mapping
287 * 3 for pages with a mapping and PagePrivate set.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800288 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700289static int migrate_page_move_mapping(struct address_space *mapping,
290 struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800291{
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800292 void **pslot;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800293
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700294 if (!mapping) {
Christoph Lameter0e8c7d02007-04-23 14:41:09 -0700295 /* Anonymous page without mapping */
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700296 if (page_count(page) != 1)
297 return -EAGAIN;
298 return 0;
299 }
300
Christoph Lameterb20a3502006-03-22 00:09:12 -0800301 write_lock_irq(&mapping->tree_lock);
302
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800303 pslot = radix_tree_lookup_slot(&mapping->page_tree,
304 page_index(page));
Christoph Lameterb20a3502006-03-22 00:09:12 -0800305
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700306 if (page_count(page) != 2 + !!PagePrivate(page) ||
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800307 (struct page *)radix_tree_deref_slot(pslot) != page) {
Christoph Lameterb20a3502006-03-22 00:09:12 -0800308 write_unlock_irq(&mapping->tree_lock);
Christoph Lametere23ca002006-04-10 22:52:57 -0700309 return -EAGAIN;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800310 }
311
312 /*
313 * Now we know that no one else is looking at the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800314 */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800315 get_page(newpage); /* add cache reference */
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700316#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800317 if (PageSwapCache(page)) {
318 SetPageSwapCache(newpage);
319 set_page_private(newpage, page_private(page));
320 }
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700321#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800322
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800323 radix_tree_replace_slot(pslot, newpage);
324
325 /*
326 * Drop cache reference from old page.
327 * We know this isn't the last reference.
328 */
Christoph Lameterb20a3502006-03-22 00:09:12 -0800329 __put_page(page);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800330
Christoph Lameter0e8c7d02007-04-23 14:41:09 -0700331 /*
332 * If moved to a different zone then also account
333 * the page for that zone. Other VM counters will be
334 * taken care of when we establish references to the
335 * new page and drop references to the old page.
336 *
337 * Note that anonymous pages are accounted for
338 * via NR_FILE_PAGES and NR_ANON_PAGES if they
339 * are mapped to swap space.
340 */
341 __dec_zone_page_state(page, NR_FILE_PAGES);
342 __inc_zone_page_state(newpage, NR_FILE_PAGES);
343
Christoph Lameterb20a3502006-03-22 00:09:12 -0800344 write_unlock_irq(&mapping->tree_lock);
345
346 return 0;
347}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800348
349/*
350 * Copy the page to its new location
351 */
Christoph Lametere7340f72006-06-23 02:03:29 -0700352static void migrate_page_copy(struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800353{
354 copy_highpage(newpage, page);
355
356 if (PageError(page))
357 SetPageError(newpage);
358 if (PageReferenced(page))
359 SetPageReferenced(newpage);
360 if (PageUptodate(page))
361 SetPageUptodate(newpage);
362 if (PageActive(page))
363 SetPageActive(newpage);
364 if (PageChecked(page))
365 SetPageChecked(newpage);
366 if (PageMappedToDisk(page))
367 SetPageMappedToDisk(newpage);
368
369 if (PageDirty(page)) {
370 clear_page_dirty_for_io(page);
371 set_page_dirty(newpage);
372 }
373
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700374#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800375 ClearPageSwapCache(page);
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700376#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800377 ClearPageActive(page);
378 ClearPagePrivate(page);
379 set_page_private(page, 0);
380 page->mapping = NULL;
381
382 /*
383 * If any waiters have accumulated on the new page then
384 * wake them up.
385 */
386 if (PageWriteback(newpage))
387 end_page_writeback(newpage);
388}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800389
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700390/************************************************************
391 * Migration functions
392 ***********************************************************/
393
394/* Always fail migration. Used for mappings that are not movable */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700395int fail_migrate_page(struct address_space *mapping,
396 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700397{
398 return -EIO;
399}
400EXPORT_SYMBOL(fail_migrate_page);
401
Christoph Lameterb20a3502006-03-22 00:09:12 -0800402/*
403 * Common logic to directly migrate a single page suitable for
404 * pages that do not use PagePrivate.
405 *
406 * Pages are locked upon entry and exit.
407 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700408int migrate_page(struct address_space *mapping,
409 struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800410{
411 int rc;
412
413 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
414
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700415 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800416
417 if (rc)
418 return rc;
419
420 migrate_page_copy(newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800421 return 0;
422}
423EXPORT_SYMBOL(migrate_page);
424
David Howells93614012006-09-30 20:45:40 +0200425#ifdef CONFIG_BLOCK
Christoph Lameterb20a3502006-03-22 00:09:12 -0800426/*
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700427 * Migration function for pages with buffers. This function can only be used
428 * if the underlying filesystem guarantees that no other references to "page"
429 * exist.
430 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700431int buffer_migrate_page(struct address_space *mapping,
432 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700433{
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700434 struct buffer_head *bh, *head;
435 int rc;
436
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700437 if (!page_has_buffers(page))
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700438 return migrate_page(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700439
440 head = page_buffers(page);
441
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700442 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700443
444 if (rc)
445 return rc;
446
447 bh = head;
448 do {
449 get_bh(bh);
450 lock_buffer(bh);
451 bh = bh->b_this_page;
452
453 } while (bh != head);
454
455 ClearPagePrivate(page);
456 set_page_private(newpage, page_private(page));
457 set_page_private(page, 0);
458 put_page(page);
459 get_page(newpage);
460
461 bh = head;
462 do {
463 set_bh_page(bh, newpage, bh_offset(bh));
464 bh = bh->b_this_page;
465
466 } while (bh != head);
467
468 SetPagePrivate(newpage);
469
470 migrate_page_copy(newpage, page);
471
472 bh = head;
473 do {
474 unlock_buffer(bh);
475 put_bh(bh);
476 bh = bh->b_this_page;
477
478 } while (bh != head);
479
480 return 0;
481}
482EXPORT_SYMBOL(buffer_migrate_page);
David Howells93614012006-09-30 20:45:40 +0200483#endif
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700484
Christoph Lameter04e62a22006-06-23 02:03:38 -0700485/*
486 * Writeback a page to clean the dirty state
487 */
488static int writeout(struct address_space *mapping, struct page *page)
489{
490 struct writeback_control wbc = {
491 .sync_mode = WB_SYNC_NONE,
492 .nr_to_write = 1,
493 .range_start = 0,
494 .range_end = LLONG_MAX,
495 .nonblocking = 1,
496 .for_reclaim = 1
497 };
498 int rc;
499
500 if (!mapping->a_ops->writepage)
501 /* No write method for the address space */
502 return -EINVAL;
503
504 if (!clear_page_dirty_for_io(page))
505 /* Someone else already triggered a write */
506 return -EAGAIN;
507
508 /*
509 * A dirty page may imply that the underlying filesystem has
510 * the page on some queue. So the page must be clean for
511 * migration. Writeout may mean we loose the lock and the
512 * page state is no longer what we checked for earlier.
513 * At this point we know that the migration attempt cannot
514 * be successful.
515 */
516 remove_migration_ptes(page, page);
517
518 rc = mapping->a_ops->writepage(page, &wbc);
519 if (rc < 0)
520 /* I/O Error writing */
521 return -EIO;
522
523 if (rc != AOP_WRITEPAGE_ACTIVATE)
524 /* unlocked. Relock */
525 lock_page(page);
526
527 return -EAGAIN;
528}
529
530/*
531 * Default handling if a filesystem does not provide a migration function.
532 */
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700533static int fallback_migrate_page(struct address_space *mapping,
534 struct page *newpage, struct page *page)
535{
Christoph Lameter04e62a22006-06-23 02:03:38 -0700536 if (PageDirty(page))
537 return writeout(mapping, page);
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700538
539 /*
540 * Buffers may be managed in a filesystem specific way.
541 * We must have no buffers or drop them.
542 */
David Howellsb398f6b2006-08-29 19:05:58 +0100543 if (PagePrivate(page) &&
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700544 !try_to_release_page(page, GFP_KERNEL))
545 return -EAGAIN;
546
547 return migrate_page(mapping, newpage, page);
548}
549
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700550/*
Christoph Lametere24f0b82006-06-23 02:03:51 -0700551 * Move a page to a newly allocated page
552 * The page is locked and all ptes have been successfully removed.
553 *
554 * The new page will have replaced the old page if this function
555 * is successful.
556 */
557static int move_to_new_page(struct page *newpage, struct page *page)
558{
559 struct address_space *mapping;
560 int rc;
561
562 /*
563 * Block others from accessing the page when we get around to
564 * establishing additional references. We are the only one
565 * holding a reference to the new page at this point.
566 */
567 if (TestSetPageLocked(newpage))
568 BUG();
569
570 /* Prepare mapping for the new page.*/
571 newpage->index = page->index;
572 newpage->mapping = page->mapping;
573
574 mapping = page_mapping(page);
575 if (!mapping)
576 rc = migrate_page(mapping, newpage, page);
577 else if (mapping->a_ops->migratepage)
578 /*
579 * Most pages have a mapping and most filesystems
580 * should provide a migration function. Anonymous
581 * pages are part of swap space which also has its
582 * own migration function. This is the most common
583 * path for page migration.
584 */
585 rc = mapping->a_ops->migratepage(mapping,
586 newpage, page);
587 else
588 rc = fallback_migrate_page(mapping, newpage, page);
589
590 if (!rc)
591 remove_migration_ptes(page, newpage);
592 else
593 newpage->mapping = NULL;
594
595 unlock_page(newpage);
596
597 return rc;
598}
599
600/*
601 * Obtain the lock on page, remove all ptes and migrate the page
602 * to the newly allocated page in newpage.
603 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700604static int unmap_and_move(new_page_t get_new_page, unsigned long private,
605 struct page *page, int force)
Christoph Lametere24f0b82006-06-23 02:03:51 -0700606{
607 int rc = 0;
Christoph Lameter742755a2006-06-23 02:03:55 -0700608 int *result = NULL;
609 struct page *newpage = get_new_page(page, private, &result);
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700610 int rcu_locked = 0;
Christoph Lameter95a402c2006-06-23 02:03:53 -0700611
612 if (!newpage)
613 return -ENOMEM;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700614
615 if (page_count(page) == 1)
616 /* page was freed from under us. So we are done. */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700617 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700618
619 rc = -EAGAIN;
620 if (TestSetPageLocked(page)) {
621 if (!force)
Christoph Lameter95a402c2006-06-23 02:03:53 -0700622 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700623 lock_page(page);
624 }
625
626 if (PageWriteback(page)) {
627 if (!force)
628 goto unlock;
629 wait_on_page_writeback(page);
630 }
Christoph Lametere24f0b82006-06-23 02:03:51 -0700631 /*
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700632 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
633 * we cannot notice that anon_vma is freed while we migrates a page.
634 * This rcu_read_lock() delays freeing anon_vma pointer until the end
635 * of migration. File cache pages are no problem because of page_lock()
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700636 * File Caches may use write_page() or lock_page() in migration, then,
637 * just care Anon page here.
Christoph Lametere24f0b82006-06-23 02:03:51 -0700638 */
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700639 if (PageAnon(page)) {
640 rcu_read_lock();
641 rcu_locked = 1;
642 }
Shaohua Li62e1c552008-02-04 22:29:33 -0800643
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700644 /*
Shaohua Li62e1c552008-02-04 22:29:33 -0800645 * Corner case handling:
646 * 1. When a new swap-cache page is read into, it is added to the LRU
647 * and treated as swapcache but it has no rmap yet.
648 * Calling try_to_unmap() against a page->mapping==NULL page will
649 * trigger a BUG. So handle it here.
650 * 2. An orphaned page (see truncate_complete_page) might have
651 * fs-private metadata. The page can be picked up due to memory
652 * offlining. Everywhere else except page reclaim, the page is
653 * invisible to the vm, so the page can not be migrated. So try to
654 * free the metadata, so the page can be freed.
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700655 */
Shaohua Li62e1c552008-02-04 22:29:33 -0800656 if (!page->mapping) {
657 if (!PageAnon(page) && PagePrivate(page)) {
658 /*
659 * Go direct to try_to_free_buffers() here because
660 * a) that's what try_to_release_page() would do anyway
661 * b) we may be under rcu_read_lock() here, so we can't
662 * use GFP_KERNEL which is what try_to_release_page()
663 * needs to be effective.
664 */
665 try_to_free_buffers(page);
666 }
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700667 goto rcu_unlock;
Shaohua Li62e1c552008-02-04 22:29:33 -0800668 }
669
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700670 /* Establish migration ptes or remove ptes */
Christoph Lametere6a15302006-06-25 05:46:49 -0700671 try_to_unmap(page, 1);
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700672
Christoph Lametere6a15302006-06-25 05:46:49 -0700673 if (!page_mapped(page))
674 rc = move_to_new_page(newpage, page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700675
676 if (rc)
677 remove_migration_ptes(page, page);
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700678rcu_unlock:
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700679 if (rcu_locked)
680 rcu_read_unlock();
Christoph Lametere6a15302006-06-25 05:46:49 -0700681
Christoph Lametere24f0b82006-06-23 02:03:51 -0700682unlock:
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700683
Christoph Lametere24f0b82006-06-23 02:03:51 -0700684 unlock_page(page);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700685
Christoph Lametere24f0b82006-06-23 02:03:51 -0700686 if (rc != -EAGAIN) {
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700687 /*
688 * A page that has been migrated has all references
689 * removed and will be freed. A page that has not been
690 * migrated will have kepts its references and be
691 * restored.
692 */
693 list_del(&page->lru);
694 move_to_lru(page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700695 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700696
697move_newpage:
698 /*
699 * Move the new page to the LRU. If migration was not successful
700 * then this will free the page.
701 */
702 move_to_lru(newpage);
Christoph Lameter742755a2006-06-23 02:03:55 -0700703 if (result) {
704 if (rc)
705 *result = rc;
706 else
707 *result = page_to_nid(newpage);
708 }
Christoph Lametere24f0b82006-06-23 02:03:51 -0700709 return rc;
710}
711
712/*
Christoph Lameterb20a3502006-03-22 00:09:12 -0800713 * migrate_pages
714 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700715 * The function takes one list of pages to migrate and a function
716 * that determines from the page to be migrated and the private data
717 * the target of the move and allocates the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800718 *
719 * The function returns after 10 attempts or if no pages
720 * are movable anymore because to has become empty
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700721 * or no retryable pages exist anymore. All pages will be
Gabriel Craciunescue9534b32007-10-20 02:13:26 +0200722 * returned to the LRU or freed.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800723 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700724 * Return: Number of pages not migrated or error code.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800725 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700726int migrate_pages(struct list_head *from,
727 new_page_t get_new_page, unsigned long private)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800728{
Christoph Lametere24f0b82006-06-23 02:03:51 -0700729 int retry = 1;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800730 int nr_failed = 0;
731 int pass = 0;
732 struct page *page;
733 struct page *page2;
734 int swapwrite = current->flags & PF_SWAPWRITE;
735 int rc;
736
737 if (!swapwrite)
738 current->flags |= PF_SWAPWRITE;
739
Christoph Lametere24f0b82006-06-23 02:03:51 -0700740 for(pass = 0; pass < 10 && retry; pass++) {
741 retry = 0;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800742
Christoph Lametere24f0b82006-06-23 02:03:51 -0700743 list_for_each_entry_safe(page, page2, from, lru) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700744 cond_resched();
Christoph Lameterb20a3502006-03-22 00:09:12 -0800745
Christoph Lameter95a402c2006-06-23 02:03:53 -0700746 rc = unmap_and_move(get_new_page, private,
747 page, pass > 2);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800748
Christoph Lametere24f0b82006-06-23 02:03:51 -0700749 switch(rc) {
Christoph Lameter95a402c2006-06-23 02:03:53 -0700750 case -ENOMEM:
751 goto out;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700752 case -EAGAIN:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700753 retry++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700754 break;
755 case 0:
Christoph Lametere24f0b82006-06-23 02:03:51 -0700756 break;
757 default:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700758 /* Permanent failure */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700759 nr_failed++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700760 break;
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700761 }
Christoph Lameterb20a3502006-03-22 00:09:12 -0800762 }
763 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700764 rc = 0;
765out:
Christoph Lameterb20a3502006-03-22 00:09:12 -0800766 if (!swapwrite)
767 current->flags &= ~PF_SWAPWRITE;
768
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700769 putback_lru_pages(from);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700770
771 if (rc)
772 return rc;
773
Christoph Lameterb20a3502006-03-22 00:09:12 -0800774 return nr_failed + retry;
775}
776
Christoph Lameter742755a2006-06-23 02:03:55 -0700777#ifdef CONFIG_NUMA
778/*
779 * Move a list of individual pages
780 */
781struct page_to_node {
782 unsigned long addr;
783 struct page *page;
784 int node;
785 int status;
786};
787
788static struct page *new_page_node(struct page *p, unsigned long private,
789 int **result)
790{
791 struct page_to_node *pm = (struct page_to_node *)private;
792
793 while (pm->node != MAX_NUMNODES && pm->page != p)
794 pm++;
795
796 if (pm->node == MAX_NUMNODES)
797 return NULL;
798
799 *result = &pm->status;
800
Mel Gorman769848c2007-07-17 04:03:05 -0700801 return alloc_pages_node(pm->node,
802 GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);
Christoph Lameter742755a2006-06-23 02:03:55 -0700803}
804
805/*
806 * Move a set of pages as indicated in the pm array. The addr
807 * field must be set to the virtual address of the page to be moved
808 * and the node number must contain a valid target node.
809 */
810static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
811 int migrate_all)
812{
813 int err;
814 struct page_to_node *pp;
815 LIST_HEAD(pagelist);
816
817 down_read(&mm->mmap_sem);
818
819 /*
820 * Build a list of pages to migrate
821 */
822 migrate_prep();
823 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
824 struct vm_area_struct *vma;
825 struct page *page;
826
827 /*
828 * A valid page pointer that will not match any of the
829 * pages that will be moved.
830 */
831 pp->page = ZERO_PAGE(0);
832
833 err = -EFAULT;
834 vma = find_vma(mm, pp->addr);
Christoph Lameter0dc952d2007-03-05 00:30:33 -0800835 if (!vma || !vma_migratable(vma))
Christoph Lameter742755a2006-06-23 02:03:55 -0700836 goto set_status;
837
838 page = follow_page(vma, pp->addr, FOLL_GET);
839 err = -ENOENT;
840 if (!page)
841 goto set_status;
842
843 if (PageReserved(page)) /* Check for zero page */
844 goto put_and_set;
845
846 pp->page = page;
847 err = page_to_nid(page);
848
849 if (err == pp->node)
850 /*
851 * Node already in the right place
852 */
853 goto put_and_set;
854
855 err = -EACCES;
856 if (page_mapcount(page) > 1 &&
857 !migrate_all)
858 goto put_and_set;
859
860 err = isolate_lru_page(page, &pagelist);
861put_and_set:
862 /*
863 * Either remove the duplicate refcount from
864 * isolate_lru_page() or drop the page ref if it was
865 * not isolated.
866 */
867 put_page(page);
868set_status:
869 pp->status = err;
870 }
871
872 if (!list_empty(&pagelist))
873 err = migrate_pages(&pagelist, new_page_node,
874 (unsigned long)pm);
875 else
876 err = -ENOENT;
877
878 up_read(&mm->mmap_sem);
879 return err;
880}
881
882/*
883 * Determine the nodes of a list of pages. The addr in the pm array
884 * must have been set to the virtual address of which we want to determine
885 * the node number.
886 */
887static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
888{
889 down_read(&mm->mmap_sem);
890
891 for ( ; pm->node != MAX_NUMNODES; pm++) {
892 struct vm_area_struct *vma;
893 struct page *page;
894 int err;
895
896 err = -EFAULT;
897 vma = find_vma(mm, pm->addr);
898 if (!vma)
899 goto set_status;
900
901 page = follow_page(vma, pm->addr, 0);
902 err = -ENOENT;
903 /* Use PageReserved to check for zero page */
904 if (!page || PageReserved(page))
905 goto set_status;
906
907 err = page_to_nid(page);
908set_status:
909 pm->status = err;
910 }
911
912 up_read(&mm->mmap_sem);
913 return 0;
914}
915
916/*
917 * Move a list of pages in the address space of the currently executing
918 * process.
919 */
920asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages,
921 const void __user * __user *pages,
922 const int __user *nodes,
923 int __user *status, int flags)
924{
925 int err = 0;
926 int i;
927 struct task_struct *task;
928 nodemask_t task_nodes;
929 struct mm_struct *mm;
930 struct page_to_node *pm = NULL;
931
932 /* Check flags */
933 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
934 return -EINVAL;
935
936 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
937 return -EPERM;
938
939 /* Find the mm_struct */
940 read_lock(&tasklist_lock);
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -0700941 task = pid ? find_task_by_vpid(pid) : current;
Christoph Lameter742755a2006-06-23 02:03:55 -0700942 if (!task) {
943 read_unlock(&tasklist_lock);
944 return -ESRCH;
945 }
946 mm = get_task_mm(task);
947 read_unlock(&tasklist_lock);
948
949 if (!mm)
950 return -EINVAL;
951
952 /*
953 * Check if this process has the right to modify the specified
954 * process. The right exists if the process has administrative
955 * capabilities, superuser privileges or the same
956 * userid as the target process.
957 */
958 if ((current->euid != task->suid) && (current->euid != task->uid) &&
959 (current->uid != task->suid) && (current->uid != task->uid) &&
960 !capable(CAP_SYS_NICE)) {
961 err = -EPERM;
962 goto out2;
963 }
964
David Quigley86c3a762006-06-23 02:04:02 -0700965 err = security_task_movememory(task);
966 if (err)
967 goto out2;
968
969
Christoph Lameter742755a2006-06-23 02:03:55 -0700970 task_nodes = cpuset_mems_allowed(task);
971
972 /* Limit nr_pages so that the multiplication may not overflow */
973 if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) {
974 err = -E2BIG;
975 goto out2;
976 }
977
978 pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node));
979 if (!pm) {
980 err = -ENOMEM;
981 goto out2;
982 }
983
984 /*
985 * Get parameters from user space and initialize the pm
986 * array. Return various errors if the user did something wrong.
987 */
988 for (i = 0; i < nr_pages; i++) {
Al Viro9d966d42007-10-14 19:34:10 +0100989 const void __user *p;
Christoph Lameter742755a2006-06-23 02:03:55 -0700990
991 err = -EFAULT;
992 if (get_user(p, pages + i))
993 goto out;
994
995 pm[i].addr = (unsigned long)p;
996 if (nodes) {
997 int node;
998
999 if (get_user(node, nodes + i))
1000 goto out;
1001
1002 err = -ENODEV;
Christoph Lameter56bbd652007-10-16 01:25:35 -07001003 if (!node_state(node, N_HIGH_MEMORY))
Christoph Lameter742755a2006-06-23 02:03:55 -07001004 goto out;
1005
1006 err = -EACCES;
1007 if (!node_isset(node, task_nodes))
1008 goto out;
1009
1010 pm[i].node = node;
Stephen Rothwell8ce08462006-11-02 22:07:28 -08001011 } else
1012 pm[i].node = 0; /* anything to not match MAX_NUMNODES */
Christoph Lameter742755a2006-06-23 02:03:55 -07001013 }
1014 /* End marker */
1015 pm[nr_pages].node = MAX_NUMNODES;
1016
1017 if (nodes)
1018 err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL);
1019 else
1020 err = do_pages_stat(mm, pm);
1021
1022 if (err >= 0)
1023 /* Return status information */
1024 for (i = 0; i < nr_pages; i++)
1025 if (put_user(pm[i].status, status + i))
1026 err = -EFAULT;
1027
1028out:
1029 vfree(pm);
1030out2:
1031 mmput(mm);
1032 return err;
1033}
1034#endif
1035
Christoph Lameter7b2259b2006-06-25 05:46:48 -07001036/*
1037 * Call migration functions in the vma_ops that may prepare
1038 * memory in a vm for migration. migration functions may perform
1039 * the migration for vmas that do not have an underlying page struct.
1040 */
1041int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
1042 const nodemask_t *from, unsigned long flags)
1043{
1044 struct vm_area_struct *vma;
1045 int err = 0;
1046
1047 for(vma = mm->mmap; vma->vm_next && !err; vma = vma->vm_next) {
1048 if (vma->vm_ops && vma->vm_ops->migrate) {
1049 err = vma->vm_ops->migrate(vma, to, from, flags);
1050 if (err)
1051 break;
1052 }
1053 }
1054 return err;
1055}