blob: 3ca6392e82cc57ccf5634fd0b27f99fd6556c9d1 [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>
Christoph Lametercde53532008-07-04 09:59:22 -070012 * Christoph Lameter
Christoph Lameterb20a3502006-03-22 00:09:12 -080013 */
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>
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080032#include <linux/memcontrol.h>
Adrian Bunk4f5ca262008-07-23 21:27:02 -070033#include <linux/syscalls.h>
Christoph Lameterb20a3502006-03-22 00:09:12 -080034
35#include "internal.h"
36
Christoph Lameterb20a3502006-03-22 00:09:12 -080037#define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru))
38
39/*
40 * Isolate one page from the LRU lists. If successful put it onto
41 * the indicated list with elevated page count.
42 *
43 * Result:
44 * -EBUSY: page not on LRU list
45 * 0: page removed from LRU list and added to the specified list.
46 */
47int isolate_lru_page(struct page *page, struct list_head *pagelist)
48{
49 int ret = -EBUSY;
50
51 if (PageLRU(page)) {
52 struct zone *zone = page_zone(page);
53
54 spin_lock_irq(&zone->lru_lock);
KAMEZAWA Hiroyuki3dd9fe82007-07-26 10:41:08 -070055 if (PageLRU(page) && get_page_unless_zero(page)) {
Christoph Lameterb20a3502006-03-22 00:09:12 -080056 ret = 0;
Christoph Lameterb20a3502006-03-22 00:09:12 -080057 ClearPageLRU(page);
58 if (PageActive(page))
59 del_page_from_active_list(zone, page);
60 else
61 del_page_from_inactive_list(zone, page);
62 list_add_tail(&page->lru, pagelist);
63 }
64 spin_unlock_irq(&zone->lru_lock);
65 }
66 return ret;
67}
68
69/*
Christoph Lameter742755a2006-06-23 02:03:55 -070070 * migrate_prep() needs to be called before we start compiling a list of pages
71 * to be migrated using isolate_lru_page().
Christoph Lameterb20a3502006-03-22 00:09:12 -080072 */
73int migrate_prep(void)
74{
Christoph Lameterb20a3502006-03-22 00:09:12 -080075 /*
76 * Clear the LRU lists so pages can be isolated.
77 * Note that pages may be moved off the LRU after we have
78 * drained them. Those pages will fail to migrate like other
79 * pages that may be busy.
80 */
81 lru_add_drain_all();
82
83 return 0;
84}
85
86static inline void move_to_lru(struct page *page)
87{
Christoph Lameterb20a3502006-03-22 00:09:12 -080088 if (PageActive(page)) {
89 /*
90 * lru_cache_add_active checks that
91 * the PG_active bit is off.
92 */
93 ClearPageActive(page);
94 lru_cache_add_active(page);
95 } else {
96 lru_cache_add(page);
97 }
98 put_page(page);
99}
100
101/*
102 * Add isolated pages on the list back to the LRU.
103 *
104 * returns the number of pages put back.
105 */
106int putback_lru_pages(struct list_head *l)
107{
108 struct page *page;
109 struct page *page2;
110 int count = 0;
111
112 list_for_each_entry_safe(page, page2, l, lru) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700113 list_del(&page->lru);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800114 move_to_lru(page);
115 count++;
116 }
117 return count;
118}
119
Christoph Lameter06972122006-06-23 02:03:35 -0700120/*
121 * Restore a potential migration pte to a working pte entry
122 */
Christoph Lameter04e62a22006-06-23 02:03:38 -0700123static void remove_migration_pte(struct vm_area_struct *vma,
Christoph Lameter06972122006-06-23 02:03:35 -0700124 struct page *old, struct page *new)
125{
126 struct mm_struct *mm = vma->vm_mm;
127 swp_entry_t entry;
128 pgd_t *pgd;
129 pud_t *pud;
130 pmd_t *pmd;
131 pte_t *ptep, pte;
132 spinlock_t *ptl;
Christoph Lameter04e62a22006-06-23 02:03:38 -0700133 unsigned long addr = page_address_in_vma(new, vma);
134
135 if (addr == -EFAULT)
136 return;
Christoph Lameter06972122006-06-23 02:03:35 -0700137
138 pgd = pgd_offset(mm, addr);
139 if (!pgd_present(*pgd))
140 return;
141
142 pud = pud_offset(pgd, addr);
143 if (!pud_present(*pud))
144 return;
145
146 pmd = pmd_offset(pud, addr);
147 if (!pmd_present(*pmd))
148 return;
149
150 ptep = pte_offset_map(pmd, addr);
151
152 if (!is_swap_pte(*ptep)) {
153 pte_unmap(ptep);
154 return;
155 }
156
157 ptl = pte_lockptr(mm, pmd);
158 spin_lock(ptl);
159 pte = *ptep;
160 if (!is_swap_pte(pte))
161 goto out;
162
163 entry = pte_to_swp_entry(pte);
164
165 if (!is_migration_entry(entry) || migration_entry_to_page(entry) != old)
166 goto out;
167
Hugh Dickins98837c72008-03-04 14:29:06 -0800168 /*
169 * Yes, ignore the return value from a GFP_ATOMIC mem_cgroup_charge.
170 * Failure is not an option here: we're now expected to remove every
171 * migration pte, and will cause crashes otherwise. Normally this
172 * is not an issue: mem_cgroup_prepare_migration bumped up the old
173 * page_cgroup count for safety, that's now attached to the new page,
174 * so this charge should just be another incrementation of the count,
175 * to keep in balance with rmap.c's mem_cgroup_uncharging. But if
176 * there's been a force_empty, those reference counts may no longer
177 * be reliable, and this charge can actually fail: oh well, we don't
178 * make the situation any worse by proceeding as if it had succeeded.
179 */
180 mem_cgroup_charge(new, mm, GFP_ATOMIC);
181
Christoph Lameter06972122006-06-23 02:03:35 -0700182 get_page(new);
183 pte = pte_mkold(mk_pte(new, vma->vm_page_prot));
184 if (is_write_migration_entry(entry))
185 pte = pte_mkwrite(pte);
KAMEZAWA Hiroyuki97ee0522007-10-16 01:25:43 -0700186 flush_cache_page(vma, addr, pte_pfn(pte));
Christoph Lameter06972122006-06-23 02:03:35 -0700187 set_pte_at(mm, addr, ptep, pte);
Christoph Lameter04e62a22006-06-23 02:03:38 -0700188
189 if (PageAnon(new))
190 page_add_anon_rmap(new, vma, addr);
191 else
192 page_add_file_rmap(new);
193
194 /* No need to invalidate - it was non-present before */
195 update_mmu_cache(vma, addr, pte);
Christoph Lameter04e62a22006-06-23 02:03:38 -0700196
Christoph Lameter06972122006-06-23 02:03:35 -0700197out:
198 pte_unmap_unlock(ptep, ptl);
199}
200
201/*
Christoph Lameter04e62a22006-06-23 02:03:38 -0700202 * Note that remove_file_migration_ptes will only work on regular mappings,
203 * Nonlinear mappings do not use migration entries.
204 */
205static void remove_file_migration_ptes(struct page *old, struct page *new)
206{
207 struct vm_area_struct *vma;
208 struct address_space *mapping = page_mapping(new);
209 struct prio_tree_iter iter;
210 pgoff_t pgoff = new->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
211
212 if (!mapping)
213 return;
214
215 spin_lock(&mapping->i_mmap_lock);
216
217 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff)
218 remove_migration_pte(vma, old, new);
219
220 spin_unlock(&mapping->i_mmap_lock);
221}
222
223/*
Christoph Lameter06972122006-06-23 02:03:35 -0700224 * Must hold mmap_sem lock on at least one of the vmas containing
225 * the page so that the anon_vma cannot vanish.
226 */
Christoph Lameter04e62a22006-06-23 02:03:38 -0700227static void remove_anon_migration_ptes(struct page *old, struct page *new)
Christoph Lameter06972122006-06-23 02:03:35 -0700228{
229 struct anon_vma *anon_vma;
230 struct vm_area_struct *vma;
231 unsigned long mapping;
232
233 mapping = (unsigned long)new->mapping;
234
235 if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
236 return;
237
238 /*
239 * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
240 */
241 anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
242 spin_lock(&anon_vma->lock);
243
244 list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
Christoph Lameter04e62a22006-06-23 02:03:38 -0700245 remove_migration_pte(vma, old, new);
Christoph Lameter06972122006-06-23 02:03:35 -0700246
247 spin_unlock(&anon_vma->lock);
248}
249
250/*
Christoph Lameter04e62a22006-06-23 02:03:38 -0700251 * Get rid of all migration entries and replace them by
252 * references to the indicated page.
253 */
254static void remove_migration_ptes(struct page *old, struct page *new)
255{
256 if (PageAnon(new))
257 remove_anon_migration_ptes(old, new);
258 else
259 remove_file_migration_ptes(old, new);
260}
261
262/*
Christoph Lameter06972122006-06-23 02:03:35 -0700263 * Something used the pte of a page under migration. We need to
264 * get to the page and wait until migration is finished.
265 * When we return from this function the fault will be retried.
266 *
267 * This function is called from do_swap_page().
268 */
269void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
270 unsigned long address)
271{
272 pte_t *ptep, pte;
273 spinlock_t *ptl;
274 swp_entry_t entry;
275 struct page *page;
276
277 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
278 pte = *ptep;
279 if (!is_swap_pte(pte))
280 goto out;
281
282 entry = pte_to_swp_entry(pte);
283 if (!is_migration_entry(entry))
284 goto out;
285
286 page = migration_entry_to_page(entry);
287
Nick Piggine2867812008-07-25 19:45:30 -0700288 /*
289 * Once radix-tree replacement of page migration started, page_count
290 * *must* be zero. And, we don't want to call wait_on_page_locked()
291 * against a page without get_page().
292 * So, we use get_page_unless_zero(), here. Even failed, page fault
293 * will occur again.
294 */
295 if (!get_page_unless_zero(page))
296 goto out;
Christoph Lameter06972122006-06-23 02:03:35 -0700297 pte_unmap_unlock(ptep, ptl);
298 wait_on_page_locked(page);
299 put_page(page);
300 return;
301out:
302 pte_unmap_unlock(ptep, ptl);
303}
304
Christoph Lameterb20a3502006-03-22 00:09:12 -0800305/*
Christoph Lameterc3fcf8a2006-06-23 02:03:32 -0700306 * Replace the page in the mapping.
Christoph Lameter5b5c7122006-06-23 02:03:29 -0700307 *
308 * The number of remaining references must be:
309 * 1 for anonymous pages without a mapping
310 * 2 for pages with a mapping
311 * 3 for pages with a mapping and PagePrivate set.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800312 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700313static int migrate_page_move_mapping(struct address_space *mapping,
314 struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800315{
Nick Piggine2867812008-07-25 19:45:30 -0700316 int expected_count;
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800317 void **pslot;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800318
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700319 if (!mapping) {
Christoph Lameter0e8c7d02007-04-23 14:41:09 -0700320 /* Anonymous page without mapping */
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700321 if (page_count(page) != 1)
322 return -EAGAIN;
323 return 0;
324 }
325
Christoph Lameterb20a3502006-03-22 00:09:12 -0800326 write_lock_irq(&mapping->tree_lock);
327
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800328 pslot = radix_tree_lookup_slot(&mapping->page_tree,
329 page_index(page));
Christoph Lameterb20a3502006-03-22 00:09:12 -0800330
Nick Piggine2867812008-07-25 19:45:30 -0700331 expected_count = 2 + !!PagePrivate(page);
332 if (page_count(page) != expected_count ||
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800333 (struct page *)radix_tree_deref_slot(pslot) != page) {
Christoph Lameterb20a3502006-03-22 00:09:12 -0800334 write_unlock_irq(&mapping->tree_lock);
Christoph Lametere23ca002006-04-10 22:52:57 -0700335 return -EAGAIN;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800336 }
337
Nick Piggine2867812008-07-25 19:45:30 -0700338 if (!page_freeze_refs(page, expected_count)) {
339 write_unlock_irq(&mapping->tree_lock);
340 return -EAGAIN;
341 }
342
Christoph Lameterb20a3502006-03-22 00:09:12 -0800343 /*
344 * Now we know that no one else is looking at the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800345 */
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800346 get_page(newpage); /* add cache reference */
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700347#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800348 if (PageSwapCache(page)) {
349 SetPageSwapCache(newpage);
350 set_page_private(newpage, page_private(page));
351 }
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700352#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800353
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800354 radix_tree_replace_slot(pslot, newpage);
355
Nick Piggine2867812008-07-25 19:45:30 -0700356 page_unfreeze_refs(page, expected_count);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800357 /*
358 * Drop cache reference from old page.
359 * We know this isn't the last reference.
360 */
Christoph Lameterb20a3502006-03-22 00:09:12 -0800361 __put_page(page);
Nick Piggin7cf9c2c2006-12-06 20:33:44 -0800362
Christoph Lameter0e8c7d02007-04-23 14:41:09 -0700363 /*
364 * If moved to a different zone then also account
365 * the page for that zone. Other VM counters will be
366 * taken care of when we establish references to the
367 * new page and drop references to the old page.
368 *
369 * Note that anonymous pages are accounted for
370 * via NR_FILE_PAGES and NR_ANON_PAGES if they
371 * are mapped to swap space.
372 */
373 __dec_zone_page_state(page, NR_FILE_PAGES);
374 __inc_zone_page_state(newpage, NR_FILE_PAGES);
375
Christoph Lameterb20a3502006-03-22 00:09:12 -0800376 write_unlock_irq(&mapping->tree_lock);
KAMEZAWA Hiroyukie8589cc2008-07-25 01:47:10 -0700377 if (!PageSwapCache(newpage)) {
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700378 mem_cgroup_uncharge_cache_page(page);
KAMEZAWA Hiroyukie8589cc2008-07-25 01:47:10 -0700379 }
Christoph Lameterb20a3502006-03-22 00:09:12 -0800380
381 return 0;
382}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800383
384/*
385 * Copy the page to its new location
386 */
Christoph Lametere7340f72006-06-23 02:03:29 -0700387static void migrate_page_copy(struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800388{
389 copy_highpage(newpage, page);
390
391 if (PageError(page))
392 SetPageError(newpage);
393 if (PageReferenced(page))
394 SetPageReferenced(newpage);
395 if (PageUptodate(page))
396 SetPageUptodate(newpage);
397 if (PageActive(page))
398 SetPageActive(newpage);
399 if (PageChecked(page))
400 SetPageChecked(newpage);
401 if (PageMappedToDisk(page))
402 SetPageMappedToDisk(newpage);
403
404 if (PageDirty(page)) {
405 clear_page_dirty_for_io(page);
Nick Piggin3a902c52008-04-30 00:55:16 -0700406 /*
407 * Want to mark the page and the radix tree as dirty, and
408 * redo the accounting that clear_page_dirty_for_io undid,
409 * but we can't use set_page_dirty because that function
410 * is actually a signal that all of the page has become dirty.
411 * Wheras only part of our page may be dirty.
412 */
413 __set_page_dirty_nobuffers(newpage);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800414 }
415
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700416#ifdef CONFIG_SWAP
Christoph Lameterb20a3502006-03-22 00:09:12 -0800417 ClearPageSwapCache(page);
Christoph Lameter6c5240a2006-06-23 02:03:37 -0700418#endif
Christoph Lameterb20a3502006-03-22 00:09:12 -0800419 ClearPageActive(page);
420 ClearPagePrivate(page);
421 set_page_private(page, 0);
422 page->mapping = NULL;
423
424 /*
425 * If any waiters have accumulated on the new page then
426 * wake them up.
427 */
428 if (PageWriteback(newpage))
429 end_page_writeback(newpage);
430}
Christoph Lameterb20a3502006-03-22 00:09:12 -0800431
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700432/************************************************************
433 * Migration functions
434 ***********************************************************/
435
436/* Always fail migration. Used for mappings that are not movable */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700437int fail_migrate_page(struct address_space *mapping,
438 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700439{
440 return -EIO;
441}
442EXPORT_SYMBOL(fail_migrate_page);
443
Christoph Lameterb20a3502006-03-22 00:09:12 -0800444/*
445 * Common logic to directly migrate a single page suitable for
446 * pages that do not use PagePrivate.
447 *
448 * Pages are locked upon entry and exit.
449 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700450int migrate_page(struct address_space *mapping,
451 struct page *newpage, struct page *page)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800452{
453 int rc;
454
455 BUG_ON(PageWriteback(page)); /* Writeback must be complete */
456
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700457 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800458
459 if (rc)
460 return rc;
461
462 migrate_page_copy(newpage, page);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800463 return 0;
464}
465EXPORT_SYMBOL(migrate_page);
466
David Howells93614012006-09-30 20:45:40 +0200467#ifdef CONFIG_BLOCK
Christoph Lameterb20a3502006-03-22 00:09:12 -0800468/*
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700469 * Migration function for pages with buffers. This function can only be used
470 * if the underlying filesystem guarantees that no other references to "page"
471 * exist.
472 */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700473int buffer_migrate_page(struct address_space *mapping,
474 struct page *newpage, struct page *page)
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700475{
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700476 struct buffer_head *bh, *head;
477 int rc;
478
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700479 if (!page_has_buffers(page))
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700480 return migrate_page(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700481
482 head = page_buffers(page);
483
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700484 rc = migrate_page_move_mapping(mapping, newpage, page);
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700485
486 if (rc)
487 return rc;
488
489 bh = head;
490 do {
491 get_bh(bh);
492 lock_buffer(bh);
493 bh = bh->b_this_page;
494
495 } while (bh != head);
496
497 ClearPagePrivate(page);
498 set_page_private(newpage, page_private(page));
499 set_page_private(page, 0);
500 put_page(page);
501 get_page(newpage);
502
503 bh = head;
504 do {
505 set_bh_page(bh, newpage, bh_offset(bh));
506 bh = bh->b_this_page;
507
508 } while (bh != head);
509
510 SetPagePrivate(newpage);
511
512 migrate_page_copy(newpage, page);
513
514 bh = head;
515 do {
516 unlock_buffer(bh);
517 put_bh(bh);
518 bh = bh->b_this_page;
519
520 } while (bh != head);
521
522 return 0;
523}
524EXPORT_SYMBOL(buffer_migrate_page);
David Howells93614012006-09-30 20:45:40 +0200525#endif
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700526
Christoph Lameter04e62a22006-06-23 02:03:38 -0700527/*
528 * Writeback a page to clean the dirty state
529 */
530static int writeout(struct address_space *mapping, struct page *page)
531{
532 struct writeback_control wbc = {
533 .sync_mode = WB_SYNC_NONE,
534 .nr_to_write = 1,
535 .range_start = 0,
536 .range_end = LLONG_MAX,
537 .nonblocking = 1,
538 .for_reclaim = 1
539 };
540 int rc;
541
542 if (!mapping->a_ops->writepage)
543 /* No write method for the address space */
544 return -EINVAL;
545
546 if (!clear_page_dirty_for_io(page))
547 /* Someone else already triggered a write */
548 return -EAGAIN;
549
550 /*
551 * A dirty page may imply that the underlying filesystem has
552 * the page on some queue. So the page must be clean for
553 * migration. Writeout may mean we loose the lock and the
554 * page state is no longer what we checked for earlier.
555 * At this point we know that the migration attempt cannot
556 * be successful.
557 */
558 remove_migration_ptes(page, page);
559
560 rc = mapping->a_ops->writepage(page, &wbc);
561 if (rc < 0)
562 /* I/O Error writing */
563 return -EIO;
564
565 if (rc != AOP_WRITEPAGE_ACTIVATE)
566 /* unlocked. Relock */
567 lock_page(page);
568
569 return -EAGAIN;
570}
571
572/*
573 * Default handling if a filesystem does not provide a migration function.
574 */
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700575static int fallback_migrate_page(struct address_space *mapping,
576 struct page *newpage, struct page *page)
577{
Christoph Lameter04e62a22006-06-23 02:03:38 -0700578 if (PageDirty(page))
579 return writeout(mapping, page);
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700580
581 /*
582 * Buffers may be managed in a filesystem specific way.
583 * We must have no buffers or drop them.
584 */
David Howellsb398f6b2006-08-29 19:05:58 +0100585 if (PagePrivate(page) &&
Christoph Lameter8351a6e2006-06-23 02:03:33 -0700586 !try_to_release_page(page, GFP_KERNEL))
587 return -EAGAIN;
588
589 return migrate_page(mapping, newpage, page);
590}
591
Christoph Lameter1d8b85c2006-06-23 02:03:28 -0700592/*
Christoph Lametere24f0b82006-06-23 02:03:51 -0700593 * Move a page to a newly allocated page
594 * The page is locked and all ptes have been successfully removed.
595 *
596 * The new page will have replaced the old page if this function
597 * is successful.
598 */
599static int move_to_new_page(struct page *newpage, struct page *page)
600{
601 struct address_space *mapping;
602 int rc;
603
604 /*
605 * Block others from accessing the page when we get around to
606 * establishing additional references. We are the only one
607 * holding a reference to the new page at this point.
608 */
609 if (TestSetPageLocked(newpage))
610 BUG();
611
612 /* Prepare mapping for the new page.*/
613 newpage->index = page->index;
614 newpage->mapping = page->mapping;
615
616 mapping = page_mapping(page);
617 if (!mapping)
618 rc = migrate_page(mapping, newpage, page);
619 else if (mapping->a_ops->migratepage)
620 /*
621 * Most pages have a mapping and most filesystems
622 * should provide a migration function. Anonymous
623 * pages are part of swap space which also has its
624 * own migration function. This is the most common
625 * path for page migration.
626 */
627 rc = mapping->a_ops->migratepage(mapping,
628 newpage, page);
629 else
630 rc = fallback_migrate_page(mapping, newpage, page);
631
KAMEZAWA Hiroyukiae41be32008-02-07 00:14:10 -0800632 if (!rc) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700633 remove_migration_ptes(page, newpage);
KAMEZAWA Hiroyukiae41be32008-02-07 00:14:10 -0800634 } else
Christoph Lametere24f0b82006-06-23 02:03:51 -0700635 newpage->mapping = NULL;
636
637 unlock_page(newpage);
638
639 return rc;
640}
641
642/*
643 * Obtain the lock on page, remove all ptes and migrate the page
644 * to the newly allocated page in newpage.
645 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700646static int unmap_and_move(new_page_t get_new_page, unsigned long private,
647 struct page *page, int force)
Christoph Lametere24f0b82006-06-23 02:03:51 -0700648{
649 int rc = 0;
Christoph Lameter742755a2006-06-23 02:03:55 -0700650 int *result = NULL;
651 struct page *newpage = get_new_page(page, private, &result);
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700652 int rcu_locked = 0;
KAMEZAWA Hiroyukiae41be32008-02-07 00:14:10 -0800653 int charge = 0;
Christoph Lameter95a402c2006-06-23 02:03:53 -0700654
655 if (!newpage)
656 return -ENOMEM;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700657
658 if (page_count(page) == 1)
659 /* page was freed from under us. So we are done. */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700660 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700661
KAMEZAWA Hiroyukie8589cc2008-07-25 01:47:10 -0700662 charge = mem_cgroup_prepare_migration(page, newpage);
663 if (charge == -ENOMEM) {
664 rc = -ENOMEM;
665 goto move_newpage;
666 }
667 /* prepare cgroup just returns 0 or -ENOMEM */
668 BUG_ON(charge);
669
Christoph Lametere24f0b82006-06-23 02:03:51 -0700670 rc = -EAGAIN;
671 if (TestSetPageLocked(page)) {
672 if (!force)
Christoph Lameter95a402c2006-06-23 02:03:53 -0700673 goto move_newpage;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700674 lock_page(page);
675 }
676
677 if (PageWriteback(page)) {
678 if (!force)
679 goto unlock;
680 wait_on_page_writeback(page);
681 }
Christoph Lametere24f0b82006-06-23 02:03:51 -0700682 /*
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700683 * By try_to_unmap(), page->mapcount goes down to 0 here. In this case,
684 * we cannot notice that anon_vma is freed while we migrates a page.
685 * This rcu_read_lock() delays freeing anon_vma pointer until the end
686 * of migration. File cache pages are no problem because of page_lock()
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700687 * File Caches may use write_page() or lock_page() in migration, then,
688 * just care Anon page here.
Christoph Lametere24f0b82006-06-23 02:03:51 -0700689 */
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700690 if (PageAnon(page)) {
691 rcu_read_lock();
692 rcu_locked = 1;
693 }
Shaohua Li62e1c552008-02-04 22:29:33 -0800694
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700695 /*
Shaohua Li62e1c552008-02-04 22:29:33 -0800696 * Corner case handling:
697 * 1. When a new swap-cache page is read into, it is added to the LRU
698 * and treated as swapcache but it has no rmap yet.
699 * Calling try_to_unmap() against a page->mapping==NULL page will
700 * trigger a BUG. So handle it here.
701 * 2. An orphaned page (see truncate_complete_page) might have
702 * fs-private metadata. The page can be picked up due to memory
703 * offlining. Everywhere else except page reclaim, the page is
704 * invisible to the vm, so the page can not be migrated. So try to
705 * free the metadata, so the page can be freed.
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700706 */
Shaohua Li62e1c552008-02-04 22:29:33 -0800707 if (!page->mapping) {
708 if (!PageAnon(page) && PagePrivate(page)) {
709 /*
710 * Go direct to try_to_free_buffers() here because
711 * a) that's what try_to_release_page() would do anyway
712 * b) we may be under rcu_read_lock() here, so we can't
713 * use GFP_KERNEL which is what try_to_release_page()
714 * needs to be effective.
715 */
716 try_to_free_buffers(page);
717 }
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700718 goto rcu_unlock;
Shaohua Li62e1c552008-02-04 22:29:33 -0800719 }
720
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700721 /* Establish migration ptes or remove ptes */
Christoph Lametere6a15302006-06-25 05:46:49 -0700722 try_to_unmap(page, 1);
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700723
Christoph Lametere6a15302006-06-25 05:46:49 -0700724 if (!page_mapped(page))
725 rc = move_to_new_page(newpage, page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700726
KAMEZAWA Hiroyukie8589cc2008-07-25 01:47:10 -0700727 if (rc)
Christoph Lametere24f0b82006-06-23 02:03:51 -0700728 remove_migration_ptes(page, page);
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700729rcu_unlock:
KAMEZAWA Hiroyuki989f89c2007-08-30 23:56:21 -0700730 if (rcu_locked)
731 rcu_read_unlock();
Christoph Lametere6a15302006-06-25 05:46:49 -0700732
Christoph Lametere24f0b82006-06-23 02:03:51 -0700733unlock:
KAMEZAWA Hiroyukidc386d42007-07-26 10:41:07 -0700734
Christoph Lametere24f0b82006-06-23 02:03:51 -0700735 unlock_page(page);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700736
Christoph Lametere24f0b82006-06-23 02:03:51 -0700737 if (rc != -EAGAIN) {
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700738 /*
739 * A page that has been migrated has all references
740 * removed and will be freed. A page that has not been
741 * migrated will have kepts its references and be
742 * restored.
743 */
744 list_del(&page->lru);
745 move_to_lru(page);
Christoph Lametere24f0b82006-06-23 02:03:51 -0700746 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700747
748move_newpage:
KAMEZAWA Hiroyukie8589cc2008-07-25 01:47:10 -0700749 if (!charge)
750 mem_cgroup_end_migration(newpage);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700751 /*
752 * Move the new page to the LRU. If migration was not successful
753 * then this will free the page.
754 */
755 move_to_lru(newpage);
Christoph Lameter742755a2006-06-23 02:03:55 -0700756 if (result) {
757 if (rc)
758 *result = rc;
759 else
760 *result = page_to_nid(newpage);
761 }
Christoph Lametere24f0b82006-06-23 02:03:51 -0700762 return rc;
763}
764
765/*
Christoph Lameterb20a3502006-03-22 00:09:12 -0800766 * migrate_pages
767 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700768 * The function takes one list of pages to migrate and a function
769 * that determines from the page to be migrated and the private data
770 * the target of the move and allocates the page.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800771 *
772 * The function returns after 10 attempts or if no pages
773 * are movable anymore because to has become empty
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700774 * or no retryable pages exist anymore. All pages will be
Gabriel Craciunescue9534b32007-10-20 02:13:26 +0200775 * returned to the LRU or freed.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800776 *
Christoph Lameter95a402c2006-06-23 02:03:53 -0700777 * Return: Number of pages not migrated or error code.
Christoph Lameterb20a3502006-03-22 00:09:12 -0800778 */
Christoph Lameter95a402c2006-06-23 02:03:53 -0700779int migrate_pages(struct list_head *from,
780 new_page_t get_new_page, unsigned long private)
Christoph Lameterb20a3502006-03-22 00:09:12 -0800781{
Christoph Lametere24f0b82006-06-23 02:03:51 -0700782 int retry = 1;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800783 int nr_failed = 0;
784 int pass = 0;
785 struct page *page;
786 struct page *page2;
787 int swapwrite = current->flags & PF_SWAPWRITE;
788 int rc;
789
790 if (!swapwrite)
791 current->flags |= PF_SWAPWRITE;
792
Christoph Lametere24f0b82006-06-23 02:03:51 -0700793 for(pass = 0; pass < 10 && retry; pass++) {
794 retry = 0;
Christoph Lameterb20a3502006-03-22 00:09:12 -0800795
Christoph Lametere24f0b82006-06-23 02:03:51 -0700796 list_for_each_entry_safe(page, page2, from, lru) {
Christoph Lametere24f0b82006-06-23 02:03:51 -0700797 cond_resched();
Christoph Lameterb20a3502006-03-22 00:09:12 -0800798
Christoph Lameter95a402c2006-06-23 02:03:53 -0700799 rc = unmap_and_move(get_new_page, private,
800 page, pass > 2);
Christoph Lameterb20a3502006-03-22 00:09:12 -0800801
Christoph Lametere24f0b82006-06-23 02:03:51 -0700802 switch(rc) {
Christoph Lameter95a402c2006-06-23 02:03:53 -0700803 case -ENOMEM:
804 goto out;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700805 case -EAGAIN:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700806 retry++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700807 break;
808 case 0:
Christoph Lametere24f0b82006-06-23 02:03:51 -0700809 break;
810 default:
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700811 /* Permanent failure */
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700812 nr_failed++;
Christoph Lametere24f0b82006-06-23 02:03:51 -0700813 break;
Christoph Lameter2d1db3b2006-06-23 02:03:33 -0700814 }
Christoph Lameterb20a3502006-03-22 00:09:12 -0800815 }
816 }
Christoph Lameter95a402c2006-06-23 02:03:53 -0700817 rc = 0;
818out:
Christoph Lameterb20a3502006-03-22 00:09:12 -0800819 if (!swapwrite)
820 current->flags &= ~PF_SWAPWRITE;
821
Christoph Lameteraaa994b2006-06-23 02:03:52 -0700822 putback_lru_pages(from);
Christoph Lameter95a402c2006-06-23 02:03:53 -0700823
824 if (rc)
825 return rc;
826
Christoph Lameterb20a3502006-03-22 00:09:12 -0800827 return nr_failed + retry;
828}
829
Christoph Lameter742755a2006-06-23 02:03:55 -0700830#ifdef CONFIG_NUMA
831/*
832 * Move a list of individual pages
833 */
834struct page_to_node {
835 unsigned long addr;
836 struct page *page;
837 int node;
838 int status;
839};
840
841static struct page *new_page_node(struct page *p, unsigned long private,
842 int **result)
843{
844 struct page_to_node *pm = (struct page_to_node *)private;
845
846 while (pm->node != MAX_NUMNODES && pm->page != p)
847 pm++;
848
849 if (pm->node == MAX_NUMNODES)
850 return NULL;
851
852 *result = &pm->status;
853
Mel Gorman769848c2007-07-17 04:03:05 -0700854 return alloc_pages_node(pm->node,
855 GFP_HIGHUSER_MOVABLE | GFP_THISNODE, 0);
Christoph Lameter742755a2006-06-23 02:03:55 -0700856}
857
858/*
859 * Move a set of pages as indicated in the pm array. The addr
860 * field must be set to the virtual address of the page to be moved
861 * and the node number must contain a valid target node.
862 */
863static int do_move_pages(struct mm_struct *mm, struct page_to_node *pm,
864 int migrate_all)
865{
866 int err;
867 struct page_to_node *pp;
868 LIST_HEAD(pagelist);
869
870 down_read(&mm->mmap_sem);
871
872 /*
873 * Build a list of pages to migrate
874 */
875 migrate_prep();
876 for (pp = pm; pp->node != MAX_NUMNODES; pp++) {
877 struct vm_area_struct *vma;
878 struct page *page;
879
880 /*
881 * A valid page pointer that will not match any of the
882 * pages that will be moved.
883 */
884 pp->page = ZERO_PAGE(0);
885
886 err = -EFAULT;
887 vma = find_vma(mm, pp->addr);
Christoph Lameter0dc952d2007-03-05 00:30:33 -0800888 if (!vma || !vma_migratable(vma))
Christoph Lameter742755a2006-06-23 02:03:55 -0700889 goto set_status;
890
891 page = follow_page(vma, pp->addr, FOLL_GET);
Linus Torvalds89f5b7d2008-06-20 11:18:25 -0700892
893 err = PTR_ERR(page);
894 if (IS_ERR(page))
895 goto set_status;
896
Christoph Lameter742755a2006-06-23 02:03:55 -0700897 err = -ENOENT;
898 if (!page)
899 goto set_status;
900
901 if (PageReserved(page)) /* Check for zero page */
902 goto put_and_set;
903
904 pp->page = page;
905 err = page_to_nid(page);
906
907 if (err == pp->node)
908 /*
909 * Node already in the right place
910 */
911 goto put_and_set;
912
913 err = -EACCES;
914 if (page_mapcount(page) > 1 &&
915 !migrate_all)
916 goto put_and_set;
917
918 err = isolate_lru_page(page, &pagelist);
919put_and_set:
920 /*
921 * Either remove the duplicate refcount from
922 * isolate_lru_page() or drop the page ref if it was
923 * not isolated.
924 */
925 put_page(page);
926set_status:
927 pp->status = err;
928 }
929
930 if (!list_empty(&pagelist))
931 err = migrate_pages(&pagelist, new_page_node,
932 (unsigned long)pm);
933 else
934 err = -ENOENT;
935
936 up_read(&mm->mmap_sem);
937 return err;
938}
939
940/*
941 * Determine the nodes of a list of pages. The addr in the pm array
942 * must have been set to the virtual address of which we want to determine
943 * the node number.
944 */
945static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
946{
947 down_read(&mm->mmap_sem);
948
949 for ( ; pm->node != MAX_NUMNODES; pm++) {
950 struct vm_area_struct *vma;
951 struct page *page;
952 int err;
953
954 err = -EFAULT;
955 vma = find_vma(mm, pm->addr);
956 if (!vma)
957 goto set_status;
958
959 page = follow_page(vma, pm->addr, 0);
Linus Torvalds89f5b7d2008-06-20 11:18:25 -0700960
961 err = PTR_ERR(page);
962 if (IS_ERR(page))
963 goto set_status;
964
Christoph Lameter742755a2006-06-23 02:03:55 -0700965 err = -ENOENT;
966 /* Use PageReserved to check for zero page */
967 if (!page || PageReserved(page))
968 goto set_status;
969
970 err = page_to_nid(page);
971set_status:
972 pm->status = err;
973 }
974
975 up_read(&mm->mmap_sem);
976 return 0;
977}
978
979/*
980 * Move a list of pages in the address space of the currently executing
981 * process.
982 */
983asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages,
984 const void __user * __user *pages,
985 const int __user *nodes,
986 int __user *status, int flags)
987{
988 int err = 0;
989 int i;
990 struct task_struct *task;
991 nodemask_t task_nodes;
992 struct mm_struct *mm;
993 struct page_to_node *pm = NULL;
994
995 /* Check flags */
996 if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
997 return -EINVAL;
998
999 if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
1000 return -EPERM;
1001
1002 /* Find the mm_struct */
1003 read_lock(&tasklist_lock);
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -07001004 task = pid ? find_task_by_vpid(pid) : current;
Christoph Lameter742755a2006-06-23 02:03:55 -07001005 if (!task) {
1006 read_unlock(&tasklist_lock);
1007 return -ESRCH;
1008 }
1009 mm = get_task_mm(task);
1010 read_unlock(&tasklist_lock);
1011
1012 if (!mm)
1013 return -EINVAL;
1014
1015 /*
1016 * Check if this process has the right to modify the specified
1017 * process. The right exists if the process has administrative
1018 * capabilities, superuser privileges or the same
1019 * userid as the target process.
1020 */
1021 if ((current->euid != task->suid) && (current->euid != task->uid) &&
1022 (current->uid != task->suid) && (current->uid != task->uid) &&
1023 !capable(CAP_SYS_NICE)) {
1024 err = -EPERM;
1025 goto out2;
1026 }
1027
David Quigley86c3a762006-06-23 02:04:02 -07001028 err = security_task_movememory(task);
1029 if (err)
1030 goto out2;
1031
1032
Christoph Lameter742755a2006-06-23 02:03:55 -07001033 task_nodes = cpuset_mems_allowed(task);
1034
1035 /* Limit nr_pages so that the multiplication may not overflow */
1036 if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) {
1037 err = -E2BIG;
1038 goto out2;
1039 }
1040
1041 pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node));
1042 if (!pm) {
1043 err = -ENOMEM;
1044 goto out2;
1045 }
1046
1047 /*
1048 * Get parameters from user space and initialize the pm
1049 * array. Return various errors if the user did something wrong.
1050 */
1051 for (i = 0; i < nr_pages; i++) {
Al Viro9d966d42007-10-14 19:34:10 +01001052 const void __user *p;
Christoph Lameter742755a2006-06-23 02:03:55 -07001053
1054 err = -EFAULT;
1055 if (get_user(p, pages + i))
1056 goto out;
1057
1058 pm[i].addr = (unsigned long)p;
1059 if (nodes) {
1060 int node;
1061
1062 if (get_user(node, nodes + i))
1063 goto out;
1064
1065 err = -ENODEV;
Christoph Lameter56bbd652007-10-16 01:25:35 -07001066 if (!node_state(node, N_HIGH_MEMORY))
Christoph Lameter742755a2006-06-23 02:03:55 -07001067 goto out;
1068
1069 err = -EACCES;
1070 if (!node_isset(node, task_nodes))
1071 goto out;
1072
1073 pm[i].node = node;
Stephen Rothwell8ce08462006-11-02 22:07:28 -08001074 } else
1075 pm[i].node = 0; /* anything to not match MAX_NUMNODES */
Christoph Lameter742755a2006-06-23 02:03:55 -07001076 }
1077 /* End marker */
1078 pm[nr_pages].node = MAX_NUMNODES;
1079
1080 if (nodes)
1081 err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL);
1082 else
1083 err = do_pages_stat(mm, pm);
1084
1085 if (err >= 0)
1086 /* Return status information */
1087 for (i = 0; i < nr_pages; i++)
1088 if (put_user(pm[i].status, status + i))
1089 err = -EFAULT;
1090
1091out:
1092 vfree(pm);
1093out2:
1094 mmput(mm);
1095 return err;
1096}
Christoph Lameter742755a2006-06-23 02:03:55 -07001097
Christoph Lameter7b2259b2006-06-25 05:46:48 -07001098/*
1099 * Call migration functions in the vma_ops that may prepare
1100 * memory in a vm for migration. migration functions may perform
1101 * the migration for vmas that do not have an underlying page struct.
1102 */
1103int migrate_vmas(struct mm_struct *mm, const nodemask_t *to,
1104 const nodemask_t *from, unsigned long flags)
1105{
1106 struct vm_area_struct *vma;
1107 int err = 0;
1108
1109 for(vma = mm->mmap; vma->vm_next && !err; vma = vma->vm_next) {
1110 if (vma->vm_ops && vma->vm_ops->migrate) {
1111 err = vma->vm_ops->migrate(vma, to, from, flags);
1112 if (err)
1113 break;
1114 }
1115 }
1116 return err;
1117}
Gerald Schaefer83d16742008-07-23 21:28:22 -07001118#endif