Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * Memory Migration functionality - linux/mm/migrate.c
4 : *
5 : * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter
6 : *
7 : * Page migration was first developed in the context of the memory hotplug
8 : * project. The main authors of the migration code are:
9 : *
10 : * IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
11 : * Hirokazu Takahashi <taka@valinux.co.jp>
12 : * Dave Hansen <haveblue@us.ibm.com>
13 : * Christoph Lameter
14 : */
15 :
16 : #include <linux/migrate.h>
17 : #include <linux/export.h>
18 : #include <linux/swap.h>
19 : #include <linux/swapops.h>
20 : #include <linux/pagemap.h>
21 : #include <linux/buffer_head.h>
22 : #include <linux/mm_inline.h>
23 : #include <linux/nsproxy.h>
24 : #include <linux/pagevec.h>
25 : #include <linux/ksm.h>
26 : #include <linux/rmap.h>
27 : #include <linux/topology.h>
28 : #include <linux/cpu.h>
29 : #include <linux/cpuset.h>
30 : #include <linux/writeback.h>
31 : #include <linux/mempolicy.h>
32 : #include <linux/vmalloc.h>
33 : #include <linux/security.h>
34 : #include <linux/backing-dev.h>
35 : #include <linux/compaction.h>
36 : #include <linux/syscalls.h>
37 : #include <linux/compat.h>
38 : #include <linux/hugetlb.h>
39 : #include <linux/hugetlb_cgroup.h>
40 : #include <linux/gfp.h>
41 : #include <linux/pfn_t.h>
42 : #include <linux/memremap.h>
43 : #include <linux/userfaultfd_k.h>
44 : #include <linux/balloon_compaction.h>
45 : #include <linux/page_idle.h>
46 : #include <linux/page_owner.h>
47 : #include <linux/sched/mm.h>
48 : #include <linux/ptrace.h>
49 : #include <linux/oom.h>
50 : #include <linux/memory.h>
51 : #include <linux/random.h>
52 : #include <linux/sched/sysctl.h>
53 : #include <linux/memory-tiers.h>
54 :
55 : #include <asm/tlbflush.h>
56 :
57 : #include <trace/events/migrate.h>
58 :
59 : #include "internal.h"
60 :
61 0 : bool isolate_movable_page(struct page *page, isolate_mode_t mode)
62 : {
63 0 : struct folio *folio = folio_get_nontail_page(page);
64 : const struct movable_operations *mops;
65 :
66 : /*
67 : * Avoid burning cycles with pages that are yet under __free_pages(),
68 : * or just got freed under us.
69 : *
70 : * In case we 'win' a race for a movable page being freed under us and
71 : * raise its refcount preventing __free_pages() from doing its job
72 : * the put_page() at the end of this block will take care of
73 : * release this page, thus avoiding a nasty leakage.
74 : */
75 0 : if (!folio)
76 : goto out;
77 :
78 0 : if (unlikely(folio_test_slab(folio)))
79 : goto out_putfolio;
80 : /* Pairs with smp_wmb() in slab freeing, e.g. SLUB's __free_slab() */
81 0 : smp_rmb();
82 : /*
83 : * Check movable flag before taking the page lock because
84 : * we use non-atomic bitops on newly allocated page flags so
85 : * unconditionally grabbing the lock ruins page's owner side.
86 : */
87 0 : if (unlikely(!__folio_test_movable(folio)))
88 : goto out_putfolio;
89 : /* Pairs with smp_wmb() in slab allocation, e.g. SLUB's alloc_slab_page() */
90 0 : smp_rmb();
91 0 : if (unlikely(folio_test_slab(folio)))
92 : goto out_putfolio;
93 :
94 : /*
95 : * As movable pages are not isolated from LRU lists, concurrent
96 : * compaction threads can race against page migration functions
97 : * as well as race against the releasing a page.
98 : *
99 : * In order to avoid having an already isolated movable page
100 : * being (wrongly) re-isolated while it is under migration,
101 : * or to avoid attempting to isolate pages being released,
102 : * lets be sure we have the page lock
103 : * before proceeding with the movable page isolation steps.
104 : */
105 0 : if (unlikely(!folio_trylock(folio)))
106 : goto out_putfolio;
107 :
108 0 : if (!folio_test_movable(folio) || folio_test_isolated(folio))
109 : goto out_no_isolated;
110 :
111 0 : mops = folio_movable_ops(folio);
112 : VM_BUG_ON_FOLIO(!mops, folio);
113 :
114 0 : if (!mops->isolate_page(&folio->page, mode))
115 : goto out_no_isolated;
116 :
117 : /* Driver shouldn't use PG_isolated bit of page->flags */
118 0 : WARN_ON_ONCE(folio_test_isolated(folio));
119 0 : folio_set_isolated(folio);
120 0 : folio_unlock(folio);
121 :
122 0 : return true;
123 :
124 : out_no_isolated:
125 0 : folio_unlock(folio);
126 : out_putfolio:
127 : folio_put(folio);
128 : out:
129 : return false;
130 : }
131 :
132 : static void putback_movable_folio(struct folio *folio)
133 : {
134 0 : const struct movable_operations *mops = folio_movable_ops(folio);
135 :
136 0 : mops->putback_page(&folio->page);
137 0 : folio_clear_isolated(folio);
138 : }
139 :
140 : /*
141 : * Put previously isolated pages back onto the appropriate lists
142 : * from where they were once taken off for compaction/migration.
143 : *
144 : * This function shall be used whenever the isolated pageset has been
145 : * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
146 : * and isolate_hugetlb().
147 : */
148 0 : void putback_movable_pages(struct list_head *l)
149 : {
150 : struct folio *folio;
151 : struct folio *folio2;
152 :
153 0 : list_for_each_entry_safe(folio, folio2, l, lru) {
154 0 : if (unlikely(folio_test_hugetlb(folio))) {
155 : folio_putback_active_hugetlb(folio);
156 : continue;
157 : }
158 0 : list_del(&folio->lru);
159 : /*
160 : * We isolated non-lru movable folio so here we can use
161 : * __PageMovable because LRU folio's mapping cannot have
162 : * PAGE_MAPPING_MOVABLE.
163 : */
164 0 : if (unlikely(__folio_test_movable(folio))) {
165 : VM_BUG_ON_FOLIO(!folio_test_isolated(folio), folio);
166 0 : folio_lock(folio);
167 0 : if (folio_test_movable(folio))
168 : putback_movable_folio(folio);
169 : else
170 : folio_clear_isolated(folio);
171 0 : folio_unlock(folio);
172 : folio_put(folio);
173 : } else {
174 0 : node_stat_mod_folio(folio, NR_ISOLATED_ANON +
175 0 : folio_is_file_lru(folio), -folio_nr_pages(folio));
176 0 : folio_putback_lru(folio);
177 : }
178 : }
179 0 : }
180 :
181 : /*
182 : * Restore a potential migration pte to a working pte entry
183 : */
184 0 : static bool remove_migration_pte(struct folio *folio,
185 : struct vm_area_struct *vma, unsigned long addr, void *old)
186 : {
187 0 : DEFINE_FOLIO_VMA_WALK(pvmw, old, vma, addr, PVMW_SYNC | PVMW_MIGRATION);
188 :
189 0 : while (page_vma_mapped_walk(&pvmw)) {
190 0 : rmap_t rmap_flags = RMAP_NONE;
191 : pte_t pte;
192 : swp_entry_t entry;
193 : struct page *new;
194 0 : unsigned long idx = 0;
195 :
196 : /* pgoff is invalid for ksm pages, but they are never large */
197 0 : if (folio_test_large(folio) && !folio_test_hugetlb(folio))
198 0 : idx = linear_page_index(vma, pvmw.address) - pvmw.pgoff;
199 0 : new = folio_page(folio, idx);
200 :
201 : #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
202 : /* PMD-mapped THP migration entry */
203 : if (!pvmw.pte) {
204 : VM_BUG_ON_FOLIO(folio_test_hugetlb(folio) ||
205 : !folio_test_pmd_mappable(folio), folio);
206 : remove_migration_pmd(&pvmw, new);
207 : continue;
208 : }
209 : #endif
210 :
211 0 : folio_get(folio);
212 0 : pte = mk_pte(new, READ_ONCE(vma->vm_page_prot));
213 0 : if (pte_swp_soft_dirty(*pvmw.pte))
214 : pte = pte_mksoft_dirty(pte);
215 :
216 0 : entry = pte_to_swp_entry(*pvmw.pte);
217 0 : if (!is_migration_entry_young(entry))
218 : pte = pte_mkold(pte);
219 0 : if (folio_test_dirty(folio) && is_migration_entry_dirty(entry))
220 : pte = pte_mkdirty(pte);
221 0 : if (is_writable_migration_entry(entry))
222 : pte = pte_mkwrite(pte);
223 : else if (pte_swp_uffd_wp(*pvmw.pte))
224 : pte = pte_mkuffd_wp(pte);
225 :
226 0 : if (folio_test_anon(folio) && !is_readable_migration_entry(entry))
227 0 : rmap_flags |= RMAP_EXCLUSIVE;
228 :
229 0 : if (unlikely(is_device_private_page(new))) {
230 : if (pte_write(pte))
231 : entry = make_writable_device_private_entry(
232 : page_to_pfn(new));
233 : else
234 : entry = make_readable_device_private_entry(
235 : page_to_pfn(new));
236 : pte = swp_entry_to_pte(entry);
237 : if (pte_swp_soft_dirty(*pvmw.pte))
238 : pte = pte_swp_mksoft_dirty(pte);
239 : if (pte_swp_uffd_wp(*pvmw.pte))
240 : pte = pte_swp_mkuffd_wp(pte);
241 : }
242 :
243 : #ifdef CONFIG_HUGETLB_PAGE
244 : if (folio_test_hugetlb(folio)) {
245 : unsigned int shift = huge_page_shift(hstate_vma(vma));
246 :
247 : pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
248 : if (folio_test_anon(folio))
249 : hugepage_add_anon_rmap(new, vma, pvmw.address,
250 : rmap_flags);
251 : else
252 : page_dup_file_rmap(new, true);
253 : set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
254 : } else
255 : #endif
256 : {
257 0 : if (folio_test_anon(folio))
258 0 : page_add_anon_rmap(new, vma, pvmw.address,
259 : rmap_flags);
260 : else
261 0 : page_add_file_rmap(new, vma, false);
262 0 : set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
263 : }
264 0 : if (vma->vm_flags & VM_LOCKED)
265 0 : mlock_drain_local();
266 :
267 : trace_remove_migration_pte(pvmw.address, pte_val(pte),
268 : compound_order(new));
269 :
270 : /* No need to invalidate - it was non-present before */
271 : update_mmu_cache(vma, pvmw.address, pvmw.pte);
272 : }
273 :
274 0 : return true;
275 : }
276 :
277 : /*
278 : * Get rid of all migration entries and replace them by
279 : * references to the indicated page.
280 : */
281 0 : void remove_migration_ptes(struct folio *src, struct folio *dst, bool locked)
282 : {
283 0 : struct rmap_walk_control rwc = {
284 : .rmap_one = remove_migration_pte,
285 : .arg = src,
286 : };
287 :
288 0 : if (locked)
289 0 : rmap_walk_locked(dst, &rwc);
290 : else
291 0 : rmap_walk(dst, &rwc);
292 0 : }
293 :
294 : /*
295 : * Something used the pte of a page under migration. We need to
296 : * get to the page and wait until migration is finished.
297 : * When we return from this function the fault will be retried.
298 : */
299 0 : void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
300 : spinlock_t *ptl)
301 : {
302 : pte_t pte;
303 : swp_entry_t entry;
304 :
305 0 : spin_lock(ptl);
306 0 : pte = *ptep;
307 0 : if (!is_swap_pte(pte))
308 : goto out;
309 :
310 0 : entry = pte_to_swp_entry(pte);
311 0 : if (!is_migration_entry(entry))
312 : goto out;
313 :
314 0 : migration_entry_wait_on_locked(entry, ptep, ptl);
315 0 : return;
316 : out:
317 0 : pte_unmap_unlock(ptep, ptl);
318 : }
319 :
320 0 : void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
321 : unsigned long address)
322 : {
323 0 : spinlock_t *ptl = pte_lockptr(mm, pmd);
324 0 : pte_t *ptep = pte_offset_map(pmd, address);
325 0 : __migration_entry_wait(mm, ptep, ptl);
326 0 : }
327 :
328 : #ifdef CONFIG_HUGETLB_PAGE
329 : /*
330 : * The vma read lock must be held upon entry. Holding that lock prevents either
331 : * the pte or the ptl from being freed.
332 : *
333 : * This function will release the vma lock before returning.
334 : */
335 : void __migration_entry_wait_huge(struct vm_area_struct *vma,
336 : pte_t *ptep, spinlock_t *ptl)
337 : {
338 : pte_t pte;
339 :
340 : hugetlb_vma_assert_locked(vma);
341 : spin_lock(ptl);
342 : pte = huge_ptep_get(ptep);
343 :
344 : if (unlikely(!is_hugetlb_entry_migration(pte))) {
345 : spin_unlock(ptl);
346 : hugetlb_vma_unlock_read(vma);
347 : } else {
348 : /*
349 : * If migration entry existed, safe to release vma lock
350 : * here because the pgtable page won't be freed without the
351 : * pgtable lock released. See comment right above pgtable
352 : * lock release in migration_entry_wait_on_locked().
353 : */
354 : hugetlb_vma_unlock_read(vma);
355 : migration_entry_wait_on_locked(pte_to_swp_entry(pte), NULL, ptl);
356 : }
357 : }
358 :
359 : void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *pte)
360 : {
361 : spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), vma->vm_mm, pte);
362 :
363 : __migration_entry_wait_huge(vma, pte, ptl);
364 : }
365 : #endif
366 :
367 : #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
368 : void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd)
369 : {
370 : spinlock_t *ptl;
371 :
372 : ptl = pmd_lock(mm, pmd);
373 : if (!is_pmd_migration_entry(*pmd))
374 : goto unlock;
375 : migration_entry_wait_on_locked(pmd_to_swp_entry(*pmd), NULL, ptl);
376 : return;
377 : unlock:
378 : spin_unlock(ptl);
379 : }
380 : #endif
381 :
382 : static int folio_expected_refs(struct address_space *mapping,
383 : struct folio *folio)
384 : {
385 0 : int refs = 1;
386 0 : if (!mapping)
387 : return refs;
388 :
389 0 : refs += folio_nr_pages(folio);
390 0 : if (folio_test_private(folio))
391 0 : refs++;
392 :
393 : return refs;
394 : }
395 :
396 : /*
397 : * Replace the page in the mapping.
398 : *
399 : * The number of remaining references must be:
400 : * 1 for anonymous pages without a mapping
401 : * 2 for pages with a mapping
402 : * 3 for pages with a mapping and PagePrivate/PagePrivate2 set.
403 : */
404 0 : int folio_migrate_mapping(struct address_space *mapping,
405 : struct folio *newfolio, struct folio *folio, int extra_count)
406 : {
407 0 : XA_STATE(xas, &mapping->i_pages, folio_index(folio));
408 : struct zone *oldzone, *newzone;
409 : int dirty;
410 0 : int expected_count = folio_expected_refs(mapping, folio) + extra_count;
411 0 : long nr = folio_nr_pages(folio);
412 :
413 0 : if (!mapping) {
414 : /* Anonymous page without mapping */
415 0 : if (folio_ref_count(folio) != expected_count)
416 : return -EAGAIN;
417 :
418 : /* No turning back from here */
419 0 : newfolio->index = folio->index;
420 0 : newfolio->mapping = folio->mapping;
421 0 : if (folio_test_swapbacked(folio))
422 : __folio_set_swapbacked(newfolio);
423 :
424 : return MIGRATEPAGE_SUCCESS;
425 : }
426 :
427 0 : oldzone = folio_zone(folio);
428 0 : newzone = folio_zone(newfolio);
429 :
430 0 : xas_lock_irq(&xas);
431 0 : if (!folio_ref_freeze(folio, expected_count)) {
432 0 : xas_unlock_irq(&xas);
433 0 : return -EAGAIN;
434 : }
435 :
436 : /*
437 : * Now we know that no one else is looking at the folio:
438 : * no turning back from here.
439 : */
440 0 : newfolio->index = folio->index;
441 0 : newfolio->mapping = folio->mapping;
442 0 : folio_ref_add(newfolio, nr); /* add cache reference */
443 0 : if (folio_test_swapbacked(folio)) {
444 0 : __folio_set_swapbacked(newfolio);
445 0 : if (folio_test_swapcache(folio)) {
446 0 : folio_set_swapcache(newfolio);
447 0 : newfolio->private = folio_get_private(folio);
448 : }
449 : } else {
450 : VM_BUG_ON_FOLIO(folio_test_swapcache(folio), folio);
451 : }
452 :
453 : /* Move dirty while page refs frozen and newpage not yet exposed */
454 0 : dirty = folio_test_dirty(folio);
455 0 : if (dirty) {
456 0 : folio_clear_dirty(folio);
457 : folio_set_dirty(newfolio);
458 : }
459 :
460 0 : xas_store(&xas, newfolio);
461 :
462 : /*
463 : * Drop cache reference from old page by unfreezing
464 : * to one less reference.
465 : * We know this isn't the last reference.
466 : */
467 0 : folio_ref_unfreeze(folio, expected_count - nr);
468 :
469 0 : xas_unlock(&xas);
470 : /* Leave irq disabled to prevent preemption while updating stats */
471 :
472 : /*
473 : * If moved to a different zone then also account
474 : * the page for that zone. Other VM counters will be
475 : * taken care of when we establish references to the
476 : * new page and drop references to the old page.
477 : *
478 : * Note that anonymous pages are accounted for
479 : * via NR_FILE_PAGES and NR_ANON_MAPPED if they
480 : * are mapped to swap space.
481 : */
482 0 : if (newzone != oldzone) {
483 : struct lruvec *old_lruvec, *new_lruvec;
484 : struct mem_cgroup *memcg;
485 :
486 0 : memcg = folio_memcg(folio);
487 0 : old_lruvec = mem_cgroup_lruvec(memcg, oldzone->zone_pgdat);
488 0 : new_lruvec = mem_cgroup_lruvec(memcg, newzone->zone_pgdat);
489 :
490 0 : __mod_lruvec_state(old_lruvec, NR_FILE_PAGES, -nr);
491 0 : __mod_lruvec_state(new_lruvec, NR_FILE_PAGES, nr);
492 0 : if (folio_test_swapbacked(folio) && !folio_test_swapcache(folio)) {
493 0 : __mod_lruvec_state(old_lruvec, NR_SHMEM, -nr);
494 0 : __mod_lruvec_state(new_lruvec, NR_SHMEM, nr);
495 : }
496 : #ifdef CONFIG_SWAP
497 0 : if (folio_test_swapcache(folio)) {
498 0 : __mod_lruvec_state(old_lruvec, NR_SWAPCACHE, -nr);
499 0 : __mod_lruvec_state(new_lruvec, NR_SWAPCACHE, nr);
500 : }
501 : #endif
502 0 : if (dirty && mapping_can_writeback(mapping)) {
503 0 : __mod_lruvec_state(old_lruvec, NR_FILE_DIRTY, -nr);
504 0 : __mod_zone_page_state(oldzone, NR_ZONE_WRITE_PENDING, -nr);
505 0 : __mod_lruvec_state(new_lruvec, NR_FILE_DIRTY, nr);
506 : __mod_zone_page_state(newzone, NR_ZONE_WRITE_PENDING, nr);
507 : }
508 : }
509 : local_irq_enable();
510 :
511 0 : return MIGRATEPAGE_SUCCESS;
512 : }
513 : EXPORT_SYMBOL(folio_migrate_mapping);
514 :
515 : /*
516 : * The expected number of remaining references is the same as that
517 : * of folio_migrate_mapping().
518 : */
519 0 : int migrate_huge_page_move_mapping(struct address_space *mapping,
520 : struct folio *dst, struct folio *src)
521 : {
522 0 : XA_STATE(xas, &mapping->i_pages, folio_index(src));
523 : int expected_count;
524 :
525 0 : xas_lock_irq(&xas);
526 0 : expected_count = 2 + folio_has_private(src);
527 0 : if (!folio_ref_freeze(src, expected_count)) {
528 0 : xas_unlock_irq(&xas);
529 0 : return -EAGAIN;
530 : }
531 :
532 0 : dst->index = src->index;
533 0 : dst->mapping = src->mapping;
534 :
535 0 : folio_get(dst);
536 :
537 0 : xas_store(&xas, dst);
538 :
539 0 : folio_ref_unfreeze(src, expected_count - 1);
540 :
541 0 : xas_unlock_irq(&xas);
542 :
543 0 : return MIGRATEPAGE_SUCCESS;
544 : }
545 :
546 : /*
547 : * Copy the flags and some other ancillary information
548 : */
549 0 : void folio_migrate_flags(struct folio *newfolio, struct folio *folio)
550 : {
551 : int cpupid;
552 :
553 0 : if (folio_test_error(folio))
554 : folio_set_error(newfolio);
555 0 : if (folio_test_referenced(folio))
556 : folio_set_referenced(newfolio);
557 0 : if (folio_test_uptodate(folio))
558 : folio_mark_uptodate(newfolio);
559 0 : if (folio_test_clear_active(folio)) {
560 : VM_BUG_ON_FOLIO(folio_test_unevictable(folio), folio);
561 : folio_set_active(newfolio);
562 0 : } else if (folio_test_clear_unevictable(folio))
563 : folio_set_unevictable(newfolio);
564 0 : if (folio_test_workingset(folio))
565 : folio_set_workingset(newfolio);
566 0 : if (folio_test_checked(folio))
567 : folio_set_checked(newfolio);
568 : /*
569 : * PG_anon_exclusive (-> PG_mappedtodisk) is always migrated via
570 : * migration entries. We can still have PG_anon_exclusive set on an
571 : * effectively unmapped and unreferenced first sub-pages of an
572 : * anonymous THP: we can simply copy it here via PG_mappedtodisk.
573 : */
574 0 : if (folio_test_mappedtodisk(folio))
575 : folio_set_mappedtodisk(newfolio);
576 :
577 : /* Move dirty on pages not done by folio_migrate_mapping() */
578 0 : if (folio_test_dirty(folio))
579 : folio_set_dirty(newfolio);
580 :
581 0 : if (folio_test_young(folio))
582 : folio_set_young(newfolio);
583 0 : if (folio_test_idle(folio))
584 : folio_set_idle(newfolio);
585 :
586 : /*
587 : * Copy NUMA information to the new page, to prevent over-eager
588 : * future migrations of this same page.
589 : */
590 0 : cpupid = page_cpupid_xchg_last(&folio->page, -1);
591 : /*
592 : * For memory tiering mode, when migrate between slow and fast
593 : * memory node, reset cpupid, because that is used to record
594 : * page access time in slow memory node.
595 : */
596 : if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) {
597 : bool f_toptier = node_is_toptier(page_to_nid(&folio->page));
598 : bool t_toptier = node_is_toptier(page_to_nid(&newfolio->page));
599 :
600 : if (f_toptier != t_toptier)
601 : cpupid = -1;
602 : }
603 0 : page_cpupid_xchg_last(&newfolio->page, cpupid);
604 :
605 0 : folio_migrate_ksm(newfolio, folio);
606 : /*
607 : * Please do not reorder this without considering how mm/ksm.c's
608 : * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
609 : */
610 0 : if (folio_test_swapcache(folio))
611 : folio_clear_swapcache(folio);
612 0 : folio_clear_private(folio);
613 :
614 : /* page->private contains hugetlb specific flags */
615 0 : if (!folio_test_hugetlb(folio))
616 0 : folio->private = NULL;
617 :
618 : /*
619 : * If any waiters have accumulated on the new page then
620 : * wake them up.
621 : */
622 0 : if (folio_test_writeback(newfolio))
623 0 : folio_end_writeback(newfolio);
624 :
625 : /*
626 : * PG_readahead shares the same bit with PG_reclaim. The above
627 : * end_page_writeback() may clear PG_readahead mistakenly, so set the
628 : * bit after that.
629 : */
630 0 : if (folio_test_readahead(folio))
631 : folio_set_readahead(newfolio);
632 :
633 0 : folio_copy_owner(newfolio, folio);
634 :
635 0 : if (!folio_test_hugetlb(folio))
636 : mem_cgroup_migrate(folio, newfolio);
637 0 : }
638 : EXPORT_SYMBOL(folio_migrate_flags);
639 :
640 0 : void folio_migrate_copy(struct folio *newfolio, struct folio *folio)
641 : {
642 0 : folio_copy(newfolio, folio);
643 0 : folio_migrate_flags(newfolio, folio);
644 0 : }
645 : EXPORT_SYMBOL(folio_migrate_copy);
646 :
647 : /************************************************************
648 : * Migration functions
649 : ***********************************************************/
650 :
651 0 : int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
652 : struct folio *src, enum migrate_mode mode, int extra_count)
653 : {
654 : int rc;
655 :
656 0 : BUG_ON(folio_test_writeback(src)); /* Writeback must be complete */
657 :
658 0 : rc = folio_migrate_mapping(mapping, dst, src, extra_count);
659 :
660 0 : if (rc != MIGRATEPAGE_SUCCESS)
661 : return rc;
662 :
663 0 : if (mode != MIGRATE_SYNC_NO_COPY)
664 : folio_migrate_copy(dst, src);
665 : else
666 0 : folio_migrate_flags(dst, src);
667 : return MIGRATEPAGE_SUCCESS;
668 : }
669 :
670 : /**
671 : * migrate_folio() - Simple folio migration.
672 : * @mapping: The address_space containing the folio.
673 : * @dst: The folio to migrate the data to.
674 : * @src: The folio containing the current data.
675 : * @mode: How to migrate the page.
676 : *
677 : * Common logic to directly migrate a single LRU folio suitable for
678 : * folios that do not use PagePrivate/PagePrivate2.
679 : *
680 : * Folios are locked upon entry and exit.
681 : */
682 0 : int migrate_folio(struct address_space *mapping, struct folio *dst,
683 : struct folio *src, enum migrate_mode mode)
684 : {
685 0 : return migrate_folio_extra(mapping, dst, src, mode, 0);
686 : }
687 : EXPORT_SYMBOL(migrate_folio);
688 :
689 : #ifdef CONFIG_BLOCK
690 : /* Returns true if all buffers are successfully locked */
691 0 : static bool buffer_migrate_lock_buffers(struct buffer_head *head,
692 : enum migrate_mode mode)
693 : {
694 0 : struct buffer_head *bh = head;
695 :
696 : /* Simple case, sync compaction */
697 0 : if (mode != MIGRATE_ASYNC) {
698 : do {
699 0 : lock_buffer(bh);
700 0 : bh = bh->b_this_page;
701 :
702 0 : } while (bh != head);
703 :
704 : return true;
705 : }
706 :
707 : /* async case, we cannot block on lock_buffer so use trylock_buffer */
708 : do {
709 0 : if (!trylock_buffer(bh)) {
710 : /*
711 : * We failed to lock the buffer and cannot stall in
712 : * async migration. Release the taken locks
713 : */
714 : struct buffer_head *failed_bh = bh;
715 : bh = head;
716 0 : while (bh != failed_bh) {
717 0 : unlock_buffer(bh);
718 0 : bh = bh->b_this_page;
719 : }
720 : return false;
721 : }
722 :
723 0 : bh = bh->b_this_page;
724 0 : } while (bh != head);
725 : return true;
726 : }
727 :
728 0 : static int __buffer_migrate_folio(struct address_space *mapping,
729 : struct folio *dst, struct folio *src, enum migrate_mode mode,
730 : bool check_refs)
731 : {
732 : struct buffer_head *bh, *head;
733 : int rc;
734 : int expected_count;
735 :
736 0 : head = folio_buffers(src);
737 0 : if (!head)
738 0 : return migrate_folio(mapping, dst, src, mode);
739 :
740 : /* Check whether page does not have extra refs before we do more work */
741 0 : expected_count = folio_expected_refs(mapping, src);
742 0 : if (folio_ref_count(src) != expected_count)
743 : return -EAGAIN;
744 :
745 0 : if (!buffer_migrate_lock_buffers(head, mode))
746 : return -EAGAIN;
747 :
748 0 : if (check_refs) {
749 : bool busy;
750 : bool invalidated = false;
751 :
752 : recheck_buffers:
753 0 : busy = false;
754 0 : spin_lock(&mapping->private_lock);
755 0 : bh = head;
756 : do {
757 0 : if (atomic_read(&bh->b_count)) {
758 : busy = true;
759 : break;
760 : }
761 0 : bh = bh->b_this_page;
762 0 : } while (bh != head);
763 0 : if (busy) {
764 0 : if (invalidated) {
765 : rc = -EAGAIN;
766 : goto unlock_buffers;
767 : }
768 0 : spin_unlock(&mapping->private_lock);
769 0 : invalidate_bh_lrus();
770 0 : invalidated = true;
771 0 : goto recheck_buffers;
772 : }
773 : }
774 :
775 0 : rc = folio_migrate_mapping(mapping, dst, src, 0);
776 0 : if (rc != MIGRATEPAGE_SUCCESS)
777 : goto unlock_buffers;
778 :
779 0 : folio_attach_private(dst, folio_detach_private(src));
780 :
781 0 : bh = head;
782 : do {
783 0 : set_bh_page(bh, &dst->page, bh_offset(bh));
784 0 : bh = bh->b_this_page;
785 0 : } while (bh != head);
786 :
787 0 : if (mode != MIGRATE_SYNC_NO_COPY)
788 : folio_migrate_copy(dst, src);
789 : else
790 0 : folio_migrate_flags(dst, src);
791 :
792 : rc = MIGRATEPAGE_SUCCESS;
793 : unlock_buffers:
794 0 : if (check_refs)
795 0 : spin_unlock(&mapping->private_lock);
796 : bh = head;
797 : do {
798 0 : unlock_buffer(bh);
799 0 : bh = bh->b_this_page;
800 0 : } while (bh != head);
801 :
802 : return rc;
803 : }
804 :
805 : /**
806 : * buffer_migrate_folio() - Migration function for folios with buffers.
807 : * @mapping: The address space containing @src.
808 : * @dst: The folio to migrate to.
809 : * @src: The folio to migrate from.
810 : * @mode: How to migrate the folio.
811 : *
812 : * This function can only be used if the underlying filesystem guarantees
813 : * that no other references to @src exist. For example attached buffer
814 : * heads are accessed only under the folio lock. If your filesystem cannot
815 : * provide this guarantee, buffer_migrate_folio_norefs() may be more
816 : * appropriate.
817 : *
818 : * Return: 0 on success or a negative errno on failure.
819 : */
820 0 : int buffer_migrate_folio(struct address_space *mapping,
821 : struct folio *dst, struct folio *src, enum migrate_mode mode)
822 : {
823 0 : return __buffer_migrate_folio(mapping, dst, src, mode, false);
824 : }
825 : EXPORT_SYMBOL(buffer_migrate_folio);
826 :
827 : /**
828 : * buffer_migrate_folio_norefs() - Migration function for folios with buffers.
829 : * @mapping: The address space containing @src.
830 : * @dst: The folio to migrate to.
831 : * @src: The folio to migrate from.
832 : * @mode: How to migrate the folio.
833 : *
834 : * Like buffer_migrate_folio() except that this variant is more careful
835 : * and checks that there are also no buffer head references. This function
836 : * is the right one for mappings where buffer heads are directly looked
837 : * up and referenced (such as block device mappings).
838 : *
839 : * Return: 0 on success or a negative errno on failure.
840 : */
841 0 : int buffer_migrate_folio_norefs(struct address_space *mapping,
842 : struct folio *dst, struct folio *src, enum migrate_mode mode)
843 : {
844 0 : return __buffer_migrate_folio(mapping, dst, src, mode, true);
845 : }
846 : EXPORT_SYMBOL_GPL(buffer_migrate_folio_norefs);
847 : #endif
848 :
849 0 : int filemap_migrate_folio(struct address_space *mapping,
850 : struct folio *dst, struct folio *src, enum migrate_mode mode)
851 : {
852 : int ret;
853 :
854 0 : ret = folio_migrate_mapping(mapping, dst, src, 0);
855 0 : if (ret != MIGRATEPAGE_SUCCESS)
856 : return ret;
857 :
858 0 : if (folio_get_private(src))
859 0 : folio_attach_private(dst, folio_detach_private(src));
860 :
861 0 : if (mode != MIGRATE_SYNC_NO_COPY)
862 : folio_migrate_copy(dst, src);
863 : else
864 0 : folio_migrate_flags(dst, src);
865 : return MIGRATEPAGE_SUCCESS;
866 : }
867 : EXPORT_SYMBOL_GPL(filemap_migrate_folio);
868 :
869 : /*
870 : * Writeback a folio to clean the dirty state
871 : */
872 0 : static int writeout(struct address_space *mapping, struct folio *folio)
873 : {
874 0 : struct writeback_control wbc = {
875 : .sync_mode = WB_SYNC_NONE,
876 : .nr_to_write = 1,
877 : .range_start = 0,
878 : .range_end = LLONG_MAX,
879 : .for_reclaim = 1
880 : };
881 : int rc;
882 :
883 0 : if (!mapping->a_ops->writepage)
884 : /* No write method for the address space */
885 : return -EINVAL;
886 :
887 0 : if (!folio_clear_dirty_for_io(folio))
888 : /* Someone else already triggered a write */
889 : return -EAGAIN;
890 :
891 : /*
892 : * A dirty folio may imply that the underlying filesystem has
893 : * the folio on some queue. So the folio must be clean for
894 : * migration. Writeout may mean we lose the lock and the
895 : * folio state is no longer what we checked for earlier.
896 : * At this point we know that the migration attempt cannot
897 : * be successful.
898 : */
899 0 : remove_migration_ptes(folio, folio, false);
900 :
901 0 : rc = mapping->a_ops->writepage(&folio->page, &wbc);
902 :
903 0 : if (rc != AOP_WRITEPAGE_ACTIVATE)
904 : /* unlocked. Relock */
905 : folio_lock(folio);
906 :
907 0 : return (rc < 0) ? -EIO : -EAGAIN;
908 : }
909 :
910 : /*
911 : * Default handling if a filesystem does not provide a migration function.
912 : */
913 0 : static int fallback_migrate_folio(struct address_space *mapping,
914 : struct folio *dst, struct folio *src, enum migrate_mode mode)
915 : {
916 0 : if (folio_test_dirty(src)) {
917 : /* Only writeback folios in full synchronous migration */
918 0 : switch (mode) {
919 : case MIGRATE_SYNC:
920 : case MIGRATE_SYNC_NO_COPY:
921 : break;
922 : default:
923 : return -EBUSY;
924 : }
925 0 : return writeout(mapping, src);
926 : }
927 :
928 : /*
929 : * Buffers may be managed in a filesystem specific way.
930 : * We must have no buffers or drop them.
931 : */
932 0 : if (folio_test_private(src) &&
933 0 : !filemap_release_folio(src, GFP_KERNEL))
934 0 : return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY;
935 :
936 0 : return migrate_folio(mapping, dst, src, mode);
937 : }
938 :
939 : /*
940 : * Move a page to a newly allocated page
941 : * The page is locked and all ptes have been successfully removed.
942 : *
943 : * The new page will have replaced the old page if this function
944 : * is successful.
945 : *
946 : * Return value:
947 : * < 0 - error code
948 : * MIGRATEPAGE_SUCCESS - success
949 : */
950 0 : static int move_to_new_folio(struct folio *dst, struct folio *src,
951 : enum migrate_mode mode)
952 : {
953 0 : int rc = -EAGAIN;
954 0 : bool is_lru = !__PageMovable(&src->page);
955 :
956 : VM_BUG_ON_FOLIO(!folio_test_locked(src), src);
957 : VM_BUG_ON_FOLIO(!folio_test_locked(dst), dst);
958 :
959 0 : if (likely(is_lru)) {
960 0 : struct address_space *mapping = folio_mapping(src);
961 :
962 0 : if (!mapping)
963 0 : rc = migrate_folio(mapping, dst, src, mode);
964 0 : else if (mapping->a_ops->migrate_folio)
965 : /*
966 : * Most folios have a mapping and most filesystems
967 : * provide a migrate_folio callback. Anonymous folios
968 : * are part of swap space which also has its own
969 : * migrate_folio callback. This is the most common path
970 : * for page migration.
971 : */
972 0 : rc = mapping->a_ops->migrate_folio(mapping, dst, src,
973 : mode);
974 : else
975 0 : rc = fallback_migrate_folio(mapping, dst, src, mode);
976 : } else {
977 : const struct movable_operations *mops;
978 :
979 : /*
980 : * In case of non-lru page, it could be released after
981 : * isolation step. In that case, we shouldn't try migration.
982 : */
983 : VM_BUG_ON_FOLIO(!folio_test_isolated(src), src);
984 0 : if (!folio_test_movable(src)) {
985 0 : rc = MIGRATEPAGE_SUCCESS;
986 : folio_clear_isolated(src);
987 : goto out;
988 : }
989 :
990 0 : mops = folio_movable_ops(src);
991 0 : rc = mops->migrate_page(&dst->page, &src->page, mode);
992 0 : WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS &&
993 : !folio_test_isolated(src));
994 : }
995 :
996 : /*
997 : * When successful, old pagecache src->mapping must be cleared before
998 : * src is freed; but stats require that PageAnon be left as PageAnon.
999 : */
1000 0 : if (rc == MIGRATEPAGE_SUCCESS) {
1001 0 : if (__PageMovable(&src->page)) {
1002 : VM_BUG_ON_FOLIO(!folio_test_isolated(src), src);
1003 :
1004 : /*
1005 : * We clear PG_movable under page_lock so any compactor
1006 : * cannot try to migrate this page.
1007 : */
1008 : folio_clear_isolated(src);
1009 : }
1010 :
1011 : /*
1012 : * Anonymous and movable src->mapping will be cleared by
1013 : * free_pages_prepare so don't reset it here for keeping
1014 : * the type to work PageAnon, for example.
1015 : */
1016 0 : if (!folio_mapping_flags(src))
1017 0 : src->mapping = NULL;
1018 :
1019 : if (likely(!folio_is_zone_device(dst)))
1020 : flush_dcache_folio(dst);
1021 : }
1022 : out:
1023 0 : return rc;
1024 : }
1025 :
1026 : /*
1027 : * To record some information during migration, we use some unused
1028 : * fields (mapping and private) of struct folio of the newly allocated
1029 : * destination folio. This is safe because nobody is using them
1030 : * except us.
1031 : */
1032 : union migration_ptr {
1033 : struct anon_vma *anon_vma;
1034 : struct address_space *mapping;
1035 : };
1036 : static void __migrate_folio_record(struct folio *dst,
1037 : unsigned long page_was_mapped,
1038 : struct anon_vma *anon_vma)
1039 : {
1040 0 : union migration_ptr ptr = { .anon_vma = anon_vma };
1041 0 : dst->mapping = ptr.mapping;
1042 0 : dst->private = (void *)page_was_mapped;
1043 : }
1044 :
1045 : static void __migrate_folio_extract(struct folio *dst,
1046 : int *page_was_mappedp,
1047 : struct anon_vma **anon_vmap)
1048 : {
1049 0 : union migration_ptr ptr = { .mapping = dst->mapping };
1050 0 : *anon_vmap = ptr.anon_vma;
1051 0 : *page_was_mappedp = (unsigned long)dst->private;
1052 0 : dst->mapping = NULL;
1053 0 : dst->private = NULL;
1054 : }
1055 :
1056 : /* Restore the source folio to the original state upon failure */
1057 0 : static void migrate_folio_undo_src(struct folio *src,
1058 : int page_was_mapped,
1059 : struct anon_vma *anon_vma,
1060 : bool locked,
1061 : struct list_head *ret)
1062 : {
1063 0 : if (page_was_mapped)
1064 0 : remove_migration_ptes(src, src, false);
1065 : /* Drop an anon_vma reference if we took one */
1066 0 : if (anon_vma)
1067 : put_anon_vma(anon_vma);
1068 0 : if (locked)
1069 0 : folio_unlock(src);
1070 0 : if (ret)
1071 0 : list_move_tail(&src->lru, ret);
1072 0 : }
1073 :
1074 : /* Restore the destination folio to the original state upon failure */
1075 0 : static void migrate_folio_undo_dst(struct folio *dst,
1076 : bool locked,
1077 : free_page_t put_new_page,
1078 : unsigned long private)
1079 : {
1080 0 : if (locked)
1081 0 : folio_unlock(dst);
1082 0 : if (put_new_page)
1083 0 : put_new_page(&dst->page, private);
1084 : else
1085 : folio_put(dst);
1086 0 : }
1087 :
1088 : /* Cleanup src folio upon migration success */
1089 0 : static void migrate_folio_done(struct folio *src,
1090 : enum migrate_reason reason)
1091 : {
1092 : /*
1093 : * Compaction can migrate also non-LRU pages which are
1094 : * not accounted to NR_ISOLATED_*. They can be recognized
1095 : * as __PageMovable
1096 : */
1097 0 : if (likely(!__folio_test_movable(src)))
1098 0 : mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON +
1099 0 : folio_is_file_lru(src), -folio_nr_pages(src));
1100 :
1101 0 : if (reason != MR_MEMORY_FAILURE)
1102 : /* We release the page in page_handle_poison. */
1103 : folio_put(src);
1104 0 : }
1105 :
1106 : /* Obtain the lock on page, remove all ptes. */
1107 0 : static int migrate_folio_unmap(new_page_t get_new_page, free_page_t put_new_page,
1108 : unsigned long private, struct folio *src,
1109 : struct folio **dstp, enum migrate_mode mode,
1110 : enum migrate_reason reason, struct list_head *ret)
1111 : {
1112 : struct folio *dst;
1113 0 : int rc = -EAGAIN;
1114 0 : struct page *newpage = NULL;
1115 0 : int page_was_mapped = 0;
1116 0 : struct anon_vma *anon_vma = NULL;
1117 0 : bool is_lru = !__PageMovable(&src->page);
1118 0 : bool locked = false;
1119 0 : bool dst_locked = false;
1120 :
1121 0 : if (folio_ref_count(src) == 1) {
1122 : /* Folio was freed from under us. So we are done. */
1123 0 : folio_clear_active(src);
1124 0 : folio_clear_unevictable(src);
1125 : /* free_pages_prepare() will clear PG_isolated. */
1126 0 : list_del(&src->lru);
1127 0 : migrate_folio_done(src, reason);
1128 0 : return MIGRATEPAGE_SUCCESS;
1129 : }
1130 :
1131 0 : newpage = get_new_page(&src->page, private);
1132 0 : if (!newpage)
1133 : return -ENOMEM;
1134 0 : dst = page_folio(newpage);
1135 0 : *dstp = dst;
1136 :
1137 0 : dst->private = NULL;
1138 :
1139 0 : if (!folio_trylock(src)) {
1140 0 : if (mode == MIGRATE_ASYNC)
1141 : goto out;
1142 :
1143 : /*
1144 : * It's not safe for direct compaction to call lock_page.
1145 : * For example, during page readahead pages are added locked
1146 : * to the LRU. Later, when the IO completes the pages are
1147 : * marked uptodate and unlocked. However, the queueing
1148 : * could be merging multiple pages for one bio (e.g.
1149 : * mpage_readahead). If an allocation happens for the
1150 : * second or third page, the process can end up locking
1151 : * the same page twice and deadlocking. Rather than
1152 : * trying to be clever about what pages can be locked,
1153 : * avoid the use of lock_page for direct compaction
1154 : * altogether.
1155 : */
1156 0 : if (current->flags & PF_MEMALLOC)
1157 : goto out;
1158 :
1159 : folio_lock(src);
1160 : }
1161 0 : locked = true;
1162 :
1163 0 : if (folio_test_writeback(src)) {
1164 : /*
1165 : * Only in the case of a full synchronous migration is it
1166 : * necessary to wait for PageWriteback. In the async case,
1167 : * the retry loop is too short and in the sync-light case,
1168 : * the overhead of stalling is too much
1169 : */
1170 0 : switch (mode) {
1171 : case MIGRATE_SYNC:
1172 : case MIGRATE_SYNC_NO_COPY:
1173 : break;
1174 : default:
1175 : rc = -EBUSY;
1176 : goto out;
1177 : }
1178 0 : folio_wait_writeback(src);
1179 : }
1180 :
1181 : /*
1182 : * By try_to_migrate(), src->mapcount goes down to 0 here. In this case,
1183 : * we cannot notice that anon_vma is freed while we migrate a page.
1184 : * This get_anon_vma() delays freeing anon_vma pointer until the end
1185 : * of migration. File cache pages are no problem because of page_lock()
1186 : * File Caches may use write_page() or lock_page() in migration, then,
1187 : * just care Anon page here.
1188 : *
1189 : * Only folio_get_anon_vma() understands the subtleties of
1190 : * getting a hold on an anon_vma from outside one of its mms.
1191 : * But if we cannot get anon_vma, then we won't need it anyway,
1192 : * because that implies that the anon page is no longer mapped
1193 : * (and cannot be remapped so long as we hold the page lock).
1194 : */
1195 0 : if (folio_test_anon(src) && !folio_test_ksm(src))
1196 0 : anon_vma = folio_get_anon_vma(src);
1197 :
1198 : /*
1199 : * Block others from accessing the new page when we get around to
1200 : * establishing additional references. We are usually the only one
1201 : * holding a reference to dst at this point. We used to have a BUG
1202 : * here if folio_trylock(dst) fails, but would like to allow for
1203 : * cases where there might be a race with the previous use of dst.
1204 : * This is much like races on refcount of oldpage: just don't BUG().
1205 : */
1206 0 : if (unlikely(!folio_trylock(dst)))
1207 : goto out;
1208 0 : dst_locked = true;
1209 :
1210 0 : if (unlikely(!is_lru)) {
1211 0 : __migrate_folio_record(dst, page_was_mapped, anon_vma);
1212 0 : return MIGRATEPAGE_UNMAP;
1213 : }
1214 :
1215 : /*
1216 : * Corner case handling:
1217 : * 1. When a new swap-cache page is read into, it is added to the LRU
1218 : * and treated as swapcache but it has no rmap yet.
1219 : * Calling try_to_unmap() against a src->mapping==NULL page will
1220 : * trigger a BUG. So handle it here.
1221 : * 2. An orphaned page (see truncate_cleanup_page) might have
1222 : * fs-private metadata. The page can be picked up due to memory
1223 : * offlining. Everywhere else except page reclaim, the page is
1224 : * invisible to the vm, so the page can not be migrated. So try to
1225 : * free the metadata, so the page can be freed.
1226 : */
1227 0 : if (!src->mapping) {
1228 0 : if (folio_test_private(src)) {
1229 0 : try_to_free_buffers(src);
1230 0 : goto out;
1231 : }
1232 0 : } else if (folio_mapped(src)) {
1233 : /* Establish migration ptes */
1234 : VM_BUG_ON_FOLIO(folio_test_anon(src) &&
1235 : !folio_test_ksm(src) && !anon_vma, src);
1236 0 : try_to_migrate(src, mode == MIGRATE_ASYNC ? TTU_BATCH_FLUSH : 0);
1237 0 : page_was_mapped = 1;
1238 : }
1239 :
1240 0 : if (!folio_mapped(src)) {
1241 0 : __migrate_folio_record(dst, page_was_mapped, anon_vma);
1242 0 : return MIGRATEPAGE_UNMAP;
1243 : }
1244 :
1245 : out:
1246 : /*
1247 : * A folio that has not been unmapped will be restored to
1248 : * right list unless we want to retry.
1249 : */
1250 0 : if (rc == -EAGAIN)
1251 0 : ret = NULL;
1252 :
1253 0 : migrate_folio_undo_src(src, page_was_mapped, anon_vma, locked, ret);
1254 0 : migrate_folio_undo_dst(dst, dst_locked, put_new_page, private);
1255 :
1256 0 : return rc;
1257 : }
1258 :
1259 : /* Migrate the folio to the newly allocated folio in dst. */
1260 0 : static int migrate_folio_move(free_page_t put_new_page, unsigned long private,
1261 : struct folio *src, struct folio *dst,
1262 : enum migrate_mode mode, enum migrate_reason reason,
1263 : struct list_head *ret)
1264 : {
1265 : int rc;
1266 0 : int page_was_mapped = 0;
1267 0 : struct anon_vma *anon_vma = NULL;
1268 0 : bool is_lru = !__PageMovable(&src->page);
1269 : struct list_head *prev;
1270 :
1271 0 : __migrate_folio_extract(dst, &page_was_mapped, &anon_vma);
1272 0 : prev = dst->lru.prev;
1273 0 : list_del(&dst->lru);
1274 :
1275 0 : rc = move_to_new_folio(dst, src, mode);
1276 0 : if (rc)
1277 : goto out;
1278 :
1279 0 : if (unlikely(!is_lru))
1280 : goto out_unlock_both;
1281 :
1282 : /*
1283 : * When successful, push dst to LRU immediately: so that if it
1284 : * turns out to be an mlocked page, remove_migration_ptes() will
1285 : * automatically build up the correct dst->mlock_count for it.
1286 : *
1287 : * We would like to do something similar for the old page, when
1288 : * unsuccessful, and other cases when a page has been temporarily
1289 : * isolated from the unevictable LRU: but this case is the easiest.
1290 : */
1291 0 : folio_add_lru(dst);
1292 0 : if (page_was_mapped)
1293 0 : lru_add_drain();
1294 :
1295 0 : if (page_was_mapped)
1296 0 : remove_migration_ptes(src, dst, false);
1297 :
1298 : out_unlock_both:
1299 0 : folio_unlock(dst);
1300 0 : set_page_owner_migrate_reason(&dst->page, reason);
1301 : /*
1302 : * If migration is successful, decrease refcount of dst,
1303 : * which will not free the page because new page owner increased
1304 : * refcounter.
1305 : */
1306 0 : folio_put(dst);
1307 :
1308 : /*
1309 : * A folio that has been migrated has all references removed
1310 : * and will be freed.
1311 : */
1312 0 : list_del(&src->lru);
1313 : /* Drop an anon_vma reference if we took one */
1314 0 : if (anon_vma)
1315 0 : put_anon_vma(anon_vma);
1316 0 : folio_unlock(src);
1317 0 : migrate_folio_done(src, reason);
1318 :
1319 0 : return rc;
1320 : out:
1321 : /*
1322 : * A folio that has not been migrated will be restored to
1323 : * right list unless we want to retry.
1324 : */
1325 0 : if (rc == -EAGAIN) {
1326 0 : list_add(&dst->lru, prev);
1327 0 : __migrate_folio_record(dst, page_was_mapped, anon_vma);
1328 0 : return rc;
1329 : }
1330 :
1331 0 : migrate_folio_undo_src(src, page_was_mapped, anon_vma, true, ret);
1332 0 : migrate_folio_undo_dst(dst, true, put_new_page, private);
1333 :
1334 0 : return rc;
1335 : }
1336 :
1337 : /*
1338 : * Counterpart of unmap_and_move_page() for hugepage migration.
1339 : *
1340 : * This function doesn't wait the completion of hugepage I/O
1341 : * because there is no race between I/O and migration for hugepage.
1342 : * Note that currently hugepage I/O occurs only in direct I/O
1343 : * where no lock is held and PG_writeback is irrelevant,
1344 : * and writeback status of all subpages are counted in the reference
1345 : * count of the head page (i.e. if all subpages of a 2MB hugepage are
1346 : * under direct I/O, the reference of the head page is 512 and a bit more.)
1347 : * This means that when we try to migrate hugepage whose subpages are
1348 : * doing direct I/O, some references remain after try_to_unmap() and
1349 : * hugepage migration fails without data corruption.
1350 : *
1351 : * There is also no race when direct I/O is issued on the page under migration,
1352 : * because then pte is replaced with migration swap entry and direct I/O code
1353 : * will wait in the page fault for migration to complete.
1354 : */
1355 : static int unmap_and_move_huge_page(new_page_t get_new_page,
1356 : free_page_t put_new_page, unsigned long private,
1357 : struct page *hpage, int force,
1358 : enum migrate_mode mode, int reason,
1359 : struct list_head *ret)
1360 : {
1361 : struct folio *dst, *src = page_folio(hpage);
1362 : int rc = -EAGAIN;
1363 : int page_was_mapped = 0;
1364 : struct page *new_hpage;
1365 : struct anon_vma *anon_vma = NULL;
1366 : struct address_space *mapping = NULL;
1367 :
1368 : if (folio_ref_count(src) == 1) {
1369 : /* page was freed from under us. So we are done. */
1370 : folio_putback_active_hugetlb(src);
1371 : return MIGRATEPAGE_SUCCESS;
1372 : }
1373 :
1374 : new_hpage = get_new_page(hpage, private);
1375 : if (!new_hpage)
1376 : return -ENOMEM;
1377 : dst = page_folio(new_hpage);
1378 :
1379 : if (!folio_trylock(src)) {
1380 : if (!force)
1381 : goto out;
1382 : switch (mode) {
1383 : case MIGRATE_SYNC:
1384 : case MIGRATE_SYNC_NO_COPY:
1385 : break;
1386 : default:
1387 : goto out;
1388 : }
1389 : folio_lock(src);
1390 : }
1391 :
1392 : /*
1393 : * Check for pages which are in the process of being freed. Without
1394 : * folio_mapping() set, hugetlbfs specific move page routine will not
1395 : * be called and we could leak usage counts for subpools.
1396 : */
1397 : if (hugetlb_folio_subpool(src) && !folio_mapping(src)) {
1398 : rc = -EBUSY;
1399 : goto out_unlock;
1400 : }
1401 :
1402 : if (folio_test_anon(src))
1403 : anon_vma = folio_get_anon_vma(src);
1404 :
1405 : if (unlikely(!folio_trylock(dst)))
1406 : goto put_anon;
1407 :
1408 : if (folio_mapped(src)) {
1409 : enum ttu_flags ttu = 0;
1410 :
1411 : if (!folio_test_anon(src)) {
1412 : /*
1413 : * In shared mappings, try_to_unmap could potentially
1414 : * call huge_pmd_unshare. Because of this, take
1415 : * semaphore in write mode here and set TTU_RMAP_LOCKED
1416 : * to let lower levels know we have taken the lock.
1417 : */
1418 : mapping = hugetlb_page_mapping_lock_write(hpage);
1419 : if (unlikely(!mapping))
1420 : goto unlock_put_anon;
1421 :
1422 : ttu = TTU_RMAP_LOCKED;
1423 : }
1424 :
1425 : try_to_migrate(src, ttu);
1426 : page_was_mapped = 1;
1427 :
1428 : if (ttu & TTU_RMAP_LOCKED)
1429 : i_mmap_unlock_write(mapping);
1430 : }
1431 :
1432 : if (!folio_mapped(src))
1433 : rc = move_to_new_folio(dst, src, mode);
1434 :
1435 : if (page_was_mapped)
1436 : remove_migration_ptes(src,
1437 : rc == MIGRATEPAGE_SUCCESS ? dst : src, false);
1438 :
1439 : unlock_put_anon:
1440 : folio_unlock(dst);
1441 :
1442 : put_anon:
1443 : if (anon_vma)
1444 : put_anon_vma(anon_vma);
1445 :
1446 : if (rc == MIGRATEPAGE_SUCCESS) {
1447 : move_hugetlb_state(src, dst, reason);
1448 : put_new_page = NULL;
1449 : }
1450 :
1451 : out_unlock:
1452 : folio_unlock(src);
1453 : out:
1454 : if (rc == MIGRATEPAGE_SUCCESS)
1455 : folio_putback_active_hugetlb(src);
1456 : else if (rc != -EAGAIN)
1457 : list_move_tail(&src->lru, ret);
1458 :
1459 : /*
1460 : * If migration was not successful and there's a freeing callback, use
1461 : * it. Otherwise, put_page() will drop the reference grabbed during
1462 : * isolation.
1463 : */
1464 : if (put_new_page)
1465 : put_new_page(new_hpage, private);
1466 : else
1467 : folio_putback_active_hugetlb(dst);
1468 :
1469 : return rc;
1470 : }
1471 :
1472 0 : static inline int try_split_folio(struct folio *folio, struct list_head *split_folios)
1473 : {
1474 : int rc;
1475 :
1476 0 : folio_lock(folio);
1477 0 : rc = split_folio_to_list(folio, split_folios);
1478 0 : folio_unlock(folio);
1479 : if (!rc)
1480 0 : list_move_tail(&folio->lru, split_folios);
1481 :
1482 0 : return rc;
1483 : }
1484 :
1485 : #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1486 : #define NR_MAX_BATCHED_MIGRATION HPAGE_PMD_NR
1487 : #else
1488 : #define NR_MAX_BATCHED_MIGRATION 512
1489 : #endif
1490 : #define NR_MAX_MIGRATE_PAGES_RETRY 10
1491 : #define NR_MAX_MIGRATE_ASYNC_RETRY 3
1492 : #define NR_MAX_MIGRATE_SYNC_RETRY \
1493 : (NR_MAX_MIGRATE_PAGES_RETRY - NR_MAX_MIGRATE_ASYNC_RETRY)
1494 :
1495 : struct migrate_pages_stats {
1496 : int nr_succeeded; /* Normal and large folios migrated successfully, in
1497 : units of base pages */
1498 : int nr_failed_pages; /* Normal and large folios failed to be migrated, in
1499 : units of base pages. Untried folios aren't counted */
1500 : int nr_thp_succeeded; /* THP migrated successfully */
1501 : int nr_thp_failed; /* THP failed to be migrated */
1502 : int nr_thp_split; /* THP split before migrating */
1503 : };
1504 :
1505 : /*
1506 : * Returns the number of hugetlb folios that were not migrated, or an error code
1507 : * after NR_MAX_MIGRATE_PAGES_RETRY attempts or if no hugetlb folios are movable
1508 : * any more because the list has become empty or no retryable hugetlb folios
1509 : * exist any more. It is caller's responsibility to call putback_movable_pages()
1510 : * only if ret != 0.
1511 : */
1512 : static int migrate_hugetlbs(struct list_head *from, new_page_t get_new_page,
1513 : free_page_t put_new_page, unsigned long private,
1514 : enum migrate_mode mode, int reason,
1515 : struct migrate_pages_stats *stats,
1516 : struct list_head *ret_folios)
1517 : {
1518 : int retry = 1;
1519 : int nr_failed = 0;
1520 : int nr_retry_pages = 0;
1521 : int pass = 0;
1522 : struct folio *folio, *folio2;
1523 : int rc, nr_pages;
1524 :
1525 0 : for (pass = 0; pass < NR_MAX_MIGRATE_PAGES_RETRY && retry; pass++) {
1526 0 : retry = 0;
1527 0 : nr_retry_pages = 0;
1528 :
1529 0 : list_for_each_entry_safe(folio, folio2, from, lru) {
1530 0 : if (!folio_test_hugetlb(folio))
1531 0 : continue;
1532 :
1533 : nr_pages = folio_nr_pages(folio);
1534 :
1535 : cond_resched();
1536 :
1537 : /*
1538 : * Migratability of hugepages depends on architectures and
1539 : * their size. This check is necessary because some callers
1540 : * of hugepage migration like soft offline and memory
1541 : * hotremove don't walk through page tables or check whether
1542 : * the hugepage is pmd-based or not before kicking migration.
1543 : */
1544 : if (!hugepage_migration_supported(folio_hstate(folio))) {
1545 : nr_failed++;
1546 : stats->nr_failed_pages += nr_pages;
1547 : list_move_tail(&folio->lru, ret_folios);
1548 : continue;
1549 : }
1550 :
1551 : rc = unmap_and_move_huge_page(get_new_page,
1552 : put_new_page, private,
1553 : &folio->page, pass > 2, mode,
1554 : reason, ret_folios);
1555 : /*
1556 : * The rules are:
1557 : * Success: hugetlb folio will be put back
1558 : * -EAGAIN: stay on the from list
1559 : * -ENOMEM: stay on the from list
1560 : * Other errno: put on ret_folios list
1561 : */
1562 : switch(rc) {
1563 : case -ENOMEM:
1564 : /*
1565 : * When memory is low, don't bother to try to migrate
1566 : * other folios, just exit.
1567 : */
1568 : stats->nr_failed_pages += nr_pages + nr_retry_pages;
1569 : return -ENOMEM;
1570 : case -EAGAIN:
1571 : retry++;
1572 : nr_retry_pages += nr_pages;
1573 : break;
1574 : case MIGRATEPAGE_SUCCESS:
1575 : stats->nr_succeeded += nr_pages;
1576 : break;
1577 : default:
1578 : /*
1579 : * Permanent failure (-EBUSY, etc.):
1580 : * unlike -EAGAIN case, the failed folio is
1581 : * removed from migration folio list and not
1582 : * retried in the next outer loop.
1583 : */
1584 : nr_failed++;
1585 : stats->nr_failed_pages += nr_pages;
1586 : break;
1587 : }
1588 : }
1589 : }
1590 : /*
1591 : * nr_failed is number of hugetlb folios failed to be migrated. After
1592 : * NR_MAX_MIGRATE_PAGES_RETRY attempts, give up and count retried hugetlb
1593 : * folios as failed.
1594 : */
1595 : nr_failed += retry;
1596 : stats->nr_failed_pages += nr_retry_pages;
1597 :
1598 : return nr_failed;
1599 : }
1600 :
1601 : /*
1602 : * migrate_pages_batch() first unmaps folios in the from list as many as
1603 : * possible, then move the unmapped folios.
1604 : *
1605 : * We only batch migration if mode == MIGRATE_ASYNC to avoid to wait a
1606 : * lock or bit when we have locked more than one folio. Which may cause
1607 : * deadlock (e.g., for loop device). So, if mode != MIGRATE_ASYNC, the
1608 : * length of the from list must be <= 1.
1609 : */
1610 0 : static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page,
1611 : free_page_t put_new_page, unsigned long private,
1612 : enum migrate_mode mode, int reason, struct list_head *ret_folios,
1613 : struct list_head *split_folios, struct migrate_pages_stats *stats,
1614 : int nr_pass)
1615 : {
1616 0 : int retry = 1;
1617 0 : int large_retry = 1;
1618 0 : int thp_retry = 1;
1619 0 : int nr_failed = 0;
1620 0 : int nr_retry_pages = 0;
1621 0 : int nr_large_failed = 0;
1622 0 : int pass = 0;
1623 0 : bool is_large = false;
1624 0 : bool is_thp = false;
1625 0 : struct folio *folio, *folio2, *dst = NULL, *dst2;
1626 0 : int rc, rc_saved = 0, nr_pages;
1627 0 : LIST_HEAD(unmap_folios);
1628 0 : LIST_HEAD(dst_folios);
1629 0 : bool nosplit = (reason == MR_NUMA_MISPLACED);
1630 :
1631 : VM_WARN_ON_ONCE(mode != MIGRATE_ASYNC &&
1632 : !list_empty(from) && !list_is_singular(from));
1633 :
1634 0 : for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
1635 0 : retry = 0;
1636 0 : large_retry = 0;
1637 0 : thp_retry = 0;
1638 0 : nr_retry_pages = 0;
1639 :
1640 0 : list_for_each_entry_safe(folio, folio2, from, lru) {
1641 : /*
1642 : * Large folio statistics is based on the source large
1643 : * folio. Capture required information that might get
1644 : * lost during migration.
1645 : */
1646 0 : is_large = folio_test_large(folio);
1647 0 : is_thp = is_large && folio_test_pmd_mappable(folio);
1648 0 : nr_pages = folio_nr_pages(folio);
1649 :
1650 0 : cond_resched();
1651 :
1652 : /*
1653 : * Large folio migration might be unsupported or
1654 : * the allocation might be failed so we should retry
1655 : * on the same folio with the large folio split
1656 : * to normal folios.
1657 : *
1658 : * Split folios are put in split_folios, and
1659 : * we will migrate them after the rest of the
1660 : * list is processed.
1661 : */
1662 : if (!thp_migration_supported() && is_thp) {
1663 : nr_large_failed++;
1664 : stats->nr_thp_failed++;
1665 : if (!try_split_folio(folio, split_folios)) {
1666 : stats->nr_thp_split++;
1667 : continue;
1668 : }
1669 : stats->nr_failed_pages += nr_pages;
1670 : list_move_tail(&folio->lru, ret_folios);
1671 : continue;
1672 : }
1673 :
1674 0 : rc = migrate_folio_unmap(get_new_page, put_new_page, private,
1675 : folio, &dst, mode, reason, ret_folios);
1676 : /*
1677 : * The rules are:
1678 : * Success: folio will be freed
1679 : * Unmap: folio will be put on unmap_folios list,
1680 : * dst folio put on dst_folios list
1681 : * -EAGAIN: stay on the from list
1682 : * -ENOMEM: stay on the from list
1683 : * Other errno: put on ret_folios list
1684 : */
1685 0 : switch(rc) {
1686 : case -ENOMEM:
1687 : /*
1688 : * When memory is low, don't bother to try to migrate
1689 : * other folios, move unmapped folios, then exit.
1690 : */
1691 0 : if (is_large) {
1692 0 : nr_large_failed++;
1693 : stats->nr_thp_failed += is_thp;
1694 : /* Large folio NUMA faulting doesn't split to retry. */
1695 0 : if (!nosplit) {
1696 0 : int ret = try_split_folio(folio, split_folios);
1697 :
1698 0 : if (!ret) {
1699 : stats->nr_thp_split += is_thp;
1700 : break;
1701 0 : } else if (reason == MR_LONGTERM_PIN &&
1702 0 : ret == -EAGAIN) {
1703 : /*
1704 : * Try again to split large folio to
1705 : * mitigate the failure of longterm pinning.
1706 : */
1707 0 : large_retry++;
1708 0 : thp_retry += is_thp;
1709 0 : nr_retry_pages += nr_pages;
1710 : /* Undo duplicated failure counting. */
1711 0 : nr_large_failed--;
1712 : stats->nr_thp_failed -= is_thp;
1713 0 : break;
1714 : }
1715 : }
1716 : } else {
1717 0 : nr_failed++;
1718 : }
1719 :
1720 0 : stats->nr_failed_pages += nr_pages + nr_retry_pages;
1721 : /* nr_failed isn't updated for not used */
1722 0 : nr_large_failed += large_retry;
1723 : stats->nr_thp_failed += thp_retry;
1724 0 : rc_saved = rc;
1725 0 : if (list_empty(&unmap_folios))
1726 : goto out;
1727 : else
1728 : goto move;
1729 : case -EAGAIN:
1730 0 : if (is_large) {
1731 0 : large_retry++;
1732 0 : thp_retry += is_thp;
1733 : } else {
1734 0 : retry++;
1735 : }
1736 0 : nr_retry_pages += nr_pages;
1737 0 : break;
1738 : case MIGRATEPAGE_SUCCESS:
1739 0 : stats->nr_succeeded += nr_pages;
1740 : stats->nr_thp_succeeded += is_thp;
1741 0 : break;
1742 : case MIGRATEPAGE_UNMAP:
1743 0 : list_move_tail(&folio->lru, &unmap_folios);
1744 0 : list_add_tail(&dst->lru, &dst_folios);
1745 : break;
1746 : default:
1747 : /*
1748 : * Permanent failure (-EBUSY, etc.):
1749 : * unlike -EAGAIN case, the failed folio is
1750 : * removed from migration folio list and not
1751 : * retried in the next outer loop.
1752 : */
1753 0 : if (is_large) {
1754 0 : nr_large_failed++;
1755 : stats->nr_thp_failed += is_thp;
1756 : } else {
1757 0 : nr_failed++;
1758 : }
1759 :
1760 0 : stats->nr_failed_pages += nr_pages;
1761 0 : break;
1762 : }
1763 : }
1764 : }
1765 0 : nr_failed += retry;
1766 0 : nr_large_failed += large_retry;
1767 0 : stats->nr_thp_failed += thp_retry;
1768 0 : stats->nr_failed_pages += nr_retry_pages;
1769 : move:
1770 : /* Flush TLBs for all unmapped folios */
1771 : try_to_unmap_flush();
1772 :
1773 0 : retry = 1;
1774 0 : for (pass = 0; pass < nr_pass && (retry || large_retry); pass++) {
1775 0 : retry = 0;
1776 0 : large_retry = 0;
1777 0 : thp_retry = 0;
1778 0 : nr_retry_pages = 0;
1779 :
1780 0 : dst = list_first_entry(&dst_folios, struct folio, lru);
1781 0 : dst2 = list_next_entry(dst, lru);
1782 0 : list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
1783 0 : is_large = folio_test_large(folio);
1784 0 : is_thp = is_large && folio_test_pmd_mappable(folio);
1785 0 : nr_pages = folio_nr_pages(folio);
1786 :
1787 0 : cond_resched();
1788 :
1789 0 : rc = migrate_folio_move(put_new_page, private,
1790 : folio, dst, mode,
1791 : reason, ret_folios);
1792 : /*
1793 : * The rules are:
1794 : * Success: folio will be freed
1795 : * -EAGAIN: stay on the unmap_folios list
1796 : * Other errno: put on ret_folios list
1797 : */
1798 0 : switch(rc) {
1799 : case -EAGAIN:
1800 0 : if (is_large) {
1801 0 : large_retry++;
1802 0 : thp_retry += is_thp;
1803 : } else {
1804 0 : retry++;
1805 : }
1806 0 : nr_retry_pages += nr_pages;
1807 0 : break;
1808 : case MIGRATEPAGE_SUCCESS:
1809 0 : stats->nr_succeeded += nr_pages;
1810 : stats->nr_thp_succeeded += is_thp;
1811 0 : break;
1812 : default:
1813 0 : if (is_large) {
1814 0 : nr_large_failed++;
1815 : stats->nr_thp_failed += is_thp;
1816 : } else {
1817 0 : nr_failed++;
1818 : }
1819 :
1820 0 : stats->nr_failed_pages += nr_pages;
1821 0 : break;
1822 : }
1823 0 : dst = dst2;
1824 0 : dst2 = list_next_entry(dst, lru);
1825 : }
1826 : }
1827 0 : nr_failed += retry;
1828 0 : nr_large_failed += large_retry;
1829 0 : stats->nr_thp_failed += thp_retry;
1830 0 : stats->nr_failed_pages += nr_retry_pages;
1831 :
1832 0 : if (rc_saved)
1833 : rc = rc_saved;
1834 : else
1835 0 : rc = nr_failed + nr_large_failed;
1836 : out:
1837 : /* Cleanup remaining folios */
1838 0 : dst = list_first_entry(&dst_folios, struct folio, lru);
1839 0 : dst2 = list_next_entry(dst, lru);
1840 0 : list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) {
1841 0 : int page_was_mapped = 0;
1842 0 : struct anon_vma *anon_vma = NULL;
1843 :
1844 0 : __migrate_folio_extract(dst, &page_was_mapped, &anon_vma);
1845 0 : migrate_folio_undo_src(folio, page_was_mapped, anon_vma,
1846 : true, ret_folios);
1847 0 : list_del(&dst->lru);
1848 0 : migrate_folio_undo_dst(dst, true, put_new_page, private);
1849 0 : dst = dst2;
1850 0 : dst2 = list_next_entry(dst, lru);
1851 : }
1852 :
1853 0 : return rc;
1854 : }
1855 :
1856 0 : static int migrate_pages_sync(struct list_head *from, new_page_t get_new_page,
1857 : free_page_t put_new_page, unsigned long private,
1858 : enum migrate_mode mode, int reason, struct list_head *ret_folios,
1859 : struct list_head *split_folios, struct migrate_pages_stats *stats)
1860 : {
1861 0 : int rc, nr_failed = 0;
1862 0 : LIST_HEAD(folios);
1863 : struct migrate_pages_stats astats;
1864 :
1865 0 : memset(&astats, 0, sizeof(astats));
1866 : /* Try to migrate in batch with MIGRATE_ASYNC mode firstly */
1867 0 : rc = migrate_pages_batch(from, get_new_page, put_new_page, private, MIGRATE_ASYNC,
1868 : reason, &folios, split_folios, &astats,
1869 : NR_MAX_MIGRATE_ASYNC_RETRY);
1870 0 : stats->nr_succeeded += astats.nr_succeeded;
1871 0 : stats->nr_thp_succeeded += astats.nr_thp_succeeded;
1872 0 : stats->nr_thp_split += astats.nr_thp_split;
1873 0 : if (rc < 0) {
1874 0 : stats->nr_failed_pages += astats.nr_failed_pages;
1875 0 : stats->nr_thp_failed += astats.nr_thp_failed;
1876 : list_splice_tail(&folios, ret_folios);
1877 : return rc;
1878 : }
1879 0 : stats->nr_thp_failed += astats.nr_thp_split;
1880 0 : nr_failed += astats.nr_thp_split;
1881 : /*
1882 : * Fall back to migrate all failed folios one by one synchronously. All
1883 : * failed folios except split THPs will be retried, so their failure
1884 : * isn't counted
1885 : */
1886 : list_splice_tail_init(&folios, from);
1887 0 : while (!list_empty(from)) {
1888 0 : list_move(from->next, &folios);
1889 0 : rc = migrate_pages_batch(&folios, get_new_page, put_new_page,
1890 : private, mode, reason, ret_folios,
1891 : split_folios, stats, NR_MAX_MIGRATE_SYNC_RETRY);
1892 0 : list_splice_tail_init(&folios, ret_folios);
1893 0 : if (rc < 0)
1894 : return rc;
1895 0 : nr_failed += rc;
1896 : }
1897 :
1898 : return nr_failed;
1899 : }
1900 :
1901 : /*
1902 : * migrate_pages - migrate the folios specified in a list, to the free folios
1903 : * supplied as the target for the page migration
1904 : *
1905 : * @from: The list of folios to be migrated.
1906 : * @get_new_page: The function used to allocate free folios to be used
1907 : * as the target of the folio migration.
1908 : * @put_new_page: The function used to free target folios if migration
1909 : * fails, or NULL if no special handling is necessary.
1910 : * @private: Private data to be passed on to get_new_page()
1911 : * @mode: The migration mode that specifies the constraints for
1912 : * folio migration, if any.
1913 : * @reason: The reason for folio migration.
1914 : * @ret_succeeded: Set to the number of folios migrated successfully if
1915 : * the caller passes a non-NULL pointer.
1916 : *
1917 : * The function returns after NR_MAX_MIGRATE_PAGES_RETRY attempts or if no folios
1918 : * are movable any more because the list has become empty or no retryable folios
1919 : * exist any more. It is caller's responsibility to call putback_movable_pages()
1920 : * only if ret != 0.
1921 : *
1922 : * Returns the number of {normal folio, large folio, hugetlb} that were not
1923 : * migrated, or an error code. The number of large folio splits will be
1924 : * considered as the number of non-migrated large folio, no matter how many
1925 : * split folios of the large folio are migrated successfully.
1926 : */
1927 0 : int migrate_pages(struct list_head *from, new_page_t get_new_page,
1928 : free_page_t put_new_page, unsigned long private,
1929 : enum migrate_mode mode, int reason, unsigned int *ret_succeeded)
1930 : {
1931 : int rc, rc_gather;
1932 : int nr_pages;
1933 : struct folio *folio, *folio2;
1934 0 : LIST_HEAD(folios);
1935 0 : LIST_HEAD(ret_folios);
1936 0 : LIST_HEAD(split_folios);
1937 : struct migrate_pages_stats stats;
1938 :
1939 0 : trace_mm_migrate_pages_start(mode, reason);
1940 :
1941 0 : memset(&stats, 0, sizeof(stats));
1942 :
1943 0 : rc_gather = migrate_hugetlbs(from, get_new_page, put_new_page, private,
1944 : mode, reason, &stats, &ret_folios);
1945 : if (rc_gather < 0)
1946 : goto out;
1947 :
1948 : again:
1949 0 : nr_pages = 0;
1950 0 : list_for_each_entry_safe(folio, folio2, from, lru) {
1951 : /* Retried hugetlb folios will be kept in list */
1952 0 : if (folio_test_hugetlb(folio)) {
1953 : list_move_tail(&folio->lru, &ret_folios);
1954 : continue;
1955 : }
1956 :
1957 0 : nr_pages += folio_nr_pages(folio);
1958 0 : if (nr_pages >= NR_MAX_BATCHED_MIGRATION)
1959 : break;
1960 : }
1961 0 : if (nr_pages >= NR_MAX_BATCHED_MIGRATION)
1962 0 : list_cut_before(&folios, from, &folio2->lru);
1963 : else
1964 : list_splice_init(from, &folios);
1965 0 : if (mode == MIGRATE_ASYNC)
1966 0 : rc = migrate_pages_batch(&folios, get_new_page, put_new_page, private,
1967 : mode, reason, &ret_folios, &split_folios, &stats,
1968 : NR_MAX_MIGRATE_PAGES_RETRY);
1969 : else
1970 0 : rc = migrate_pages_sync(&folios, get_new_page, put_new_page, private,
1971 : mode, reason, &ret_folios, &split_folios, &stats);
1972 0 : list_splice_tail_init(&folios, &ret_folios);
1973 0 : if (rc < 0) {
1974 0 : rc_gather = rc;
1975 : list_splice_tail(&split_folios, &ret_folios);
1976 : goto out;
1977 : }
1978 0 : if (!list_empty(&split_folios)) {
1979 : /*
1980 : * Failure isn't counted since all split folios of a large folio
1981 : * is counted as 1 failure already. And, we only try to migrate
1982 : * with minimal effort, force MIGRATE_ASYNC mode and retry once.
1983 : */
1984 0 : migrate_pages_batch(&split_folios, get_new_page, put_new_page, private,
1985 : MIGRATE_ASYNC, reason, &ret_folios, NULL, &stats, 1);
1986 : list_splice_tail_init(&split_folios, &ret_folios);
1987 : }
1988 0 : rc_gather += rc;
1989 0 : if (!list_empty(from))
1990 : goto again;
1991 : out:
1992 : /*
1993 : * Put the permanent failure folio back to migration list, they
1994 : * will be put back to the right list by the caller.
1995 : */
1996 0 : list_splice(&ret_folios, from);
1997 :
1998 : /*
1999 : * Return 0 in case all split folios of fail-to-migrate large folios
2000 : * are migrated successfully.
2001 : */
2002 0 : if (list_empty(from))
2003 0 : rc_gather = 0;
2004 :
2005 0 : count_vm_events(PGMIGRATE_SUCCESS, stats.nr_succeeded);
2006 0 : count_vm_events(PGMIGRATE_FAIL, stats.nr_failed_pages);
2007 0 : count_vm_events(THP_MIGRATION_SUCCESS, stats.nr_thp_succeeded);
2008 0 : count_vm_events(THP_MIGRATION_FAIL, stats.nr_thp_failed);
2009 0 : count_vm_events(THP_MIGRATION_SPLIT, stats.nr_thp_split);
2010 0 : trace_mm_migrate_pages(stats.nr_succeeded, stats.nr_failed_pages,
2011 0 : stats.nr_thp_succeeded, stats.nr_thp_failed,
2012 0 : stats.nr_thp_split, mode, reason);
2013 :
2014 0 : if (ret_succeeded)
2015 0 : *ret_succeeded = stats.nr_succeeded;
2016 :
2017 0 : return rc_gather;
2018 : }
2019 :
2020 0 : struct page *alloc_migration_target(struct page *page, unsigned long private)
2021 : {
2022 0 : struct folio *folio = page_folio(page);
2023 : struct migration_target_control *mtc;
2024 : gfp_t gfp_mask;
2025 0 : unsigned int order = 0;
2026 0 : struct folio *hugetlb_folio = NULL;
2027 0 : struct folio *new_folio = NULL;
2028 : int nid;
2029 : int zidx;
2030 :
2031 0 : mtc = (struct migration_target_control *)private;
2032 0 : gfp_mask = mtc->gfp_mask;
2033 0 : nid = mtc->nid;
2034 0 : if (nid == NUMA_NO_NODE)
2035 0 : nid = folio_nid(folio);
2036 :
2037 0 : if (folio_test_hugetlb(folio)) {
2038 : struct hstate *h = folio_hstate(folio);
2039 :
2040 : gfp_mask = htlb_modify_alloc_mask(h, gfp_mask);
2041 : hugetlb_folio = alloc_hugetlb_folio_nodemask(h, nid,
2042 : mtc->nmask, gfp_mask);
2043 : return &hugetlb_folio->page;
2044 : }
2045 :
2046 0 : if (folio_test_large(folio)) {
2047 : /*
2048 : * clear __GFP_RECLAIM to make the migration callback
2049 : * consistent with regular THP allocations.
2050 : */
2051 0 : gfp_mask &= ~__GFP_RECLAIM;
2052 0 : gfp_mask |= GFP_TRANSHUGE;
2053 : order = folio_order(folio);
2054 : }
2055 0 : zidx = zone_idx(folio_zone(folio));
2056 0 : if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE)
2057 0 : gfp_mask |= __GFP_HIGHMEM;
2058 :
2059 0 : new_folio = __folio_alloc(gfp_mask, order, nid, mtc->nmask);
2060 :
2061 0 : return &new_folio->page;
2062 : }
2063 :
2064 : #ifdef CONFIG_NUMA
2065 :
2066 : static int store_status(int __user *status, int start, int value, int nr)
2067 : {
2068 : while (nr-- > 0) {
2069 : if (put_user(value, status + start))
2070 : return -EFAULT;
2071 : start++;
2072 : }
2073 :
2074 : return 0;
2075 : }
2076 :
2077 : static int do_move_pages_to_node(struct mm_struct *mm,
2078 : struct list_head *pagelist, int node)
2079 : {
2080 : int err;
2081 : struct migration_target_control mtc = {
2082 : .nid = node,
2083 : .gfp_mask = GFP_HIGHUSER_MOVABLE | __GFP_THISNODE,
2084 : };
2085 :
2086 : err = migrate_pages(pagelist, alloc_migration_target, NULL,
2087 : (unsigned long)&mtc, MIGRATE_SYNC, MR_SYSCALL, NULL);
2088 : if (err)
2089 : putback_movable_pages(pagelist);
2090 : return err;
2091 : }
2092 :
2093 : /*
2094 : * Resolves the given address to a struct page, isolates it from the LRU and
2095 : * puts it to the given pagelist.
2096 : * Returns:
2097 : * errno - if the page cannot be found/isolated
2098 : * 0 - when it doesn't have to be migrated because it is already on the
2099 : * target node
2100 : * 1 - when it has been queued
2101 : */
2102 : static int add_page_for_migration(struct mm_struct *mm, const void __user *p,
2103 : int node, struct list_head *pagelist, bool migrate_all)
2104 : {
2105 : struct vm_area_struct *vma;
2106 : unsigned long addr;
2107 : struct page *page;
2108 : int err;
2109 : bool isolated;
2110 :
2111 : mmap_read_lock(mm);
2112 : addr = (unsigned long)untagged_addr_remote(mm, p);
2113 :
2114 : err = -EFAULT;
2115 : vma = vma_lookup(mm, addr);
2116 : if (!vma || !vma_migratable(vma))
2117 : goto out;
2118 :
2119 : /* FOLL_DUMP to ignore special (like zero) pages */
2120 : page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
2121 :
2122 : err = PTR_ERR(page);
2123 : if (IS_ERR(page))
2124 : goto out;
2125 :
2126 : err = -ENOENT;
2127 : if (!page)
2128 : goto out;
2129 :
2130 : if (is_zone_device_page(page))
2131 : goto out_putpage;
2132 :
2133 : err = 0;
2134 : if (page_to_nid(page) == node)
2135 : goto out_putpage;
2136 :
2137 : err = -EACCES;
2138 : if (page_mapcount(page) > 1 && !migrate_all)
2139 : goto out_putpage;
2140 :
2141 : if (PageHuge(page)) {
2142 : if (PageHead(page)) {
2143 : isolated = isolate_hugetlb(page_folio(page), pagelist);
2144 : err = isolated ? 1 : -EBUSY;
2145 : }
2146 : } else {
2147 : struct page *head;
2148 :
2149 : head = compound_head(page);
2150 : isolated = isolate_lru_page(head);
2151 : if (!isolated) {
2152 : err = -EBUSY;
2153 : goto out_putpage;
2154 : }
2155 :
2156 : err = 1;
2157 : list_add_tail(&head->lru, pagelist);
2158 : mod_node_page_state(page_pgdat(head),
2159 : NR_ISOLATED_ANON + page_is_file_lru(head),
2160 : thp_nr_pages(head));
2161 : }
2162 : out_putpage:
2163 : /*
2164 : * Either remove the duplicate refcount from
2165 : * isolate_lru_page() or drop the page ref if it was
2166 : * not isolated.
2167 : */
2168 : put_page(page);
2169 : out:
2170 : mmap_read_unlock(mm);
2171 : return err;
2172 : }
2173 :
2174 : static int move_pages_and_store_status(struct mm_struct *mm, int node,
2175 : struct list_head *pagelist, int __user *status,
2176 : int start, int i, unsigned long nr_pages)
2177 : {
2178 : int err;
2179 :
2180 : if (list_empty(pagelist))
2181 : return 0;
2182 :
2183 : err = do_move_pages_to_node(mm, pagelist, node);
2184 : if (err) {
2185 : /*
2186 : * Positive err means the number of failed
2187 : * pages to migrate. Since we are going to
2188 : * abort and return the number of non-migrated
2189 : * pages, so need to include the rest of the
2190 : * nr_pages that have not been attempted as
2191 : * well.
2192 : */
2193 : if (err > 0)
2194 : err += nr_pages - i;
2195 : return err;
2196 : }
2197 : return store_status(status, start, node, i - start);
2198 : }
2199 :
2200 : /*
2201 : * Migrate an array of page address onto an array of nodes and fill
2202 : * the corresponding array of status.
2203 : */
2204 : static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
2205 : unsigned long nr_pages,
2206 : const void __user * __user *pages,
2207 : const int __user *nodes,
2208 : int __user *status, int flags)
2209 : {
2210 : int current_node = NUMA_NO_NODE;
2211 : LIST_HEAD(pagelist);
2212 : int start, i;
2213 : int err = 0, err1;
2214 :
2215 : lru_cache_disable();
2216 :
2217 : for (i = start = 0; i < nr_pages; i++) {
2218 : const void __user *p;
2219 : int node;
2220 :
2221 : err = -EFAULT;
2222 : if (get_user(p, pages + i))
2223 : goto out_flush;
2224 : if (get_user(node, nodes + i))
2225 : goto out_flush;
2226 :
2227 : err = -ENODEV;
2228 : if (node < 0 || node >= MAX_NUMNODES)
2229 : goto out_flush;
2230 : if (!node_state(node, N_MEMORY))
2231 : goto out_flush;
2232 :
2233 : err = -EACCES;
2234 : if (!node_isset(node, task_nodes))
2235 : goto out_flush;
2236 :
2237 : if (current_node == NUMA_NO_NODE) {
2238 : current_node = node;
2239 : start = i;
2240 : } else if (node != current_node) {
2241 : err = move_pages_and_store_status(mm, current_node,
2242 : &pagelist, status, start, i, nr_pages);
2243 : if (err)
2244 : goto out;
2245 : start = i;
2246 : current_node = node;
2247 : }
2248 :
2249 : /*
2250 : * Errors in the page lookup or isolation are not fatal and we simply
2251 : * report them via status
2252 : */
2253 : err = add_page_for_migration(mm, p, current_node, &pagelist,
2254 : flags & MPOL_MF_MOVE_ALL);
2255 :
2256 : if (err > 0) {
2257 : /* The page is successfully queued for migration */
2258 : continue;
2259 : }
2260 :
2261 : /*
2262 : * The move_pages() man page does not have an -EEXIST choice, so
2263 : * use -EFAULT instead.
2264 : */
2265 : if (err == -EEXIST)
2266 : err = -EFAULT;
2267 :
2268 : /*
2269 : * If the page is already on the target node (!err), store the
2270 : * node, otherwise, store the err.
2271 : */
2272 : err = store_status(status, i, err ? : current_node, 1);
2273 : if (err)
2274 : goto out_flush;
2275 :
2276 : err = move_pages_and_store_status(mm, current_node, &pagelist,
2277 : status, start, i, nr_pages);
2278 : if (err) {
2279 : /* We have accounted for page i */
2280 : if (err > 0)
2281 : err--;
2282 : goto out;
2283 : }
2284 : current_node = NUMA_NO_NODE;
2285 : }
2286 : out_flush:
2287 : /* Make sure we do not overwrite the existing error */
2288 : err1 = move_pages_and_store_status(mm, current_node, &pagelist,
2289 : status, start, i, nr_pages);
2290 : if (err >= 0)
2291 : err = err1;
2292 : out:
2293 : lru_cache_enable();
2294 : return err;
2295 : }
2296 :
2297 : /*
2298 : * Determine the nodes of an array of pages and store it in an array of status.
2299 : */
2300 : static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
2301 : const void __user **pages, int *status)
2302 : {
2303 : unsigned long i;
2304 :
2305 : mmap_read_lock(mm);
2306 :
2307 : for (i = 0; i < nr_pages; i++) {
2308 : unsigned long addr = (unsigned long)(*pages);
2309 : struct vm_area_struct *vma;
2310 : struct page *page;
2311 : int err = -EFAULT;
2312 :
2313 : vma = vma_lookup(mm, addr);
2314 : if (!vma)
2315 : goto set_status;
2316 :
2317 : /* FOLL_DUMP to ignore special (like zero) pages */
2318 : page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
2319 :
2320 : err = PTR_ERR(page);
2321 : if (IS_ERR(page))
2322 : goto set_status;
2323 :
2324 : err = -ENOENT;
2325 : if (!page)
2326 : goto set_status;
2327 :
2328 : if (!is_zone_device_page(page))
2329 : err = page_to_nid(page);
2330 :
2331 : put_page(page);
2332 : set_status:
2333 : *status = err;
2334 :
2335 : pages++;
2336 : status++;
2337 : }
2338 :
2339 : mmap_read_unlock(mm);
2340 : }
2341 :
2342 : static int get_compat_pages_array(const void __user *chunk_pages[],
2343 : const void __user * __user *pages,
2344 : unsigned long chunk_nr)
2345 : {
2346 : compat_uptr_t __user *pages32 = (compat_uptr_t __user *)pages;
2347 : compat_uptr_t p;
2348 : int i;
2349 :
2350 : for (i = 0; i < chunk_nr; i++) {
2351 : if (get_user(p, pages32 + i))
2352 : return -EFAULT;
2353 : chunk_pages[i] = compat_ptr(p);
2354 : }
2355 :
2356 : return 0;
2357 : }
2358 :
2359 : /*
2360 : * Determine the nodes of a user array of pages and store it in
2361 : * a user array of status.
2362 : */
2363 : static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
2364 : const void __user * __user *pages,
2365 : int __user *status)
2366 : {
2367 : #define DO_PAGES_STAT_CHUNK_NR 16UL
2368 : const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
2369 : int chunk_status[DO_PAGES_STAT_CHUNK_NR];
2370 :
2371 : while (nr_pages) {
2372 : unsigned long chunk_nr = min(nr_pages, DO_PAGES_STAT_CHUNK_NR);
2373 :
2374 : if (in_compat_syscall()) {
2375 : if (get_compat_pages_array(chunk_pages, pages,
2376 : chunk_nr))
2377 : break;
2378 : } else {
2379 : if (copy_from_user(chunk_pages, pages,
2380 : chunk_nr * sizeof(*chunk_pages)))
2381 : break;
2382 : }
2383 :
2384 : do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
2385 :
2386 : if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
2387 : break;
2388 :
2389 : pages += chunk_nr;
2390 : status += chunk_nr;
2391 : nr_pages -= chunk_nr;
2392 : }
2393 : return nr_pages ? -EFAULT : 0;
2394 : }
2395 :
2396 : static struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes)
2397 : {
2398 : struct task_struct *task;
2399 : struct mm_struct *mm;
2400 :
2401 : /*
2402 : * There is no need to check if current process has the right to modify
2403 : * the specified process when they are same.
2404 : */
2405 : if (!pid) {
2406 : mmget(current->mm);
2407 : *mem_nodes = cpuset_mems_allowed(current);
2408 : return current->mm;
2409 : }
2410 :
2411 : /* Find the mm_struct */
2412 : rcu_read_lock();
2413 : task = find_task_by_vpid(pid);
2414 : if (!task) {
2415 : rcu_read_unlock();
2416 : return ERR_PTR(-ESRCH);
2417 : }
2418 : get_task_struct(task);
2419 :
2420 : /*
2421 : * Check if this process has the right to modify the specified
2422 : * process. Use the regular "ptrace_may_access()" checks.
2423 : */
2424 : if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
2425 : rcu_read_unlock();
2426 : mm = ERR_PTR(-EPERM);
2427 : goto out;
2428 : }
2429 : rcu_read_unlock();
2430 :
2431 : mm = ERR_PTR(security_task_movememory(task));
2432 : if (IS_ERR(mm))
2433 : goto out;
2434 : *mem_nodes = cpuset_mems_allowed(task);
2435 : mm = get_task_mm(task);
2436 : out:
2437 : put_task_struct(task);
2438 : if (!mm)
2439 : mm = ERR_PTR(-EINVAL);
2440 : return mm;
2441 : }
2442 :
2443 : /*
2444 : * Move a list of pages in the address space of the currently executing
2445 : * process.
2446 : */
2447 : static int kernel_move_pages(pid_t pid, unsigned long nr_pages,
2448 : const void __user * __user *pages,
2449 : const int __user *nodes,
2450 : int __user *status, int flags)
2451 : {
2452 : struct mm_struct *mm;
2453 : int err;
2454 : nodemask_t task_nodes;
2455 :
2456 : /* Check flags */
2457 : if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL))
2458 : return -EINVAL;
2459 :
2460 : if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
2461 : return -EPERM;
2462 :
2463 : mm = find_mm_struct(pid, &task_nodes);
2464 : if (IS_ERR(mm))
2465 : return PTR_ERR(mm);
2466 :
2467 : if (nodes)
2468 : err = do_pages_move(mm, task_nodes, nr_pages, pages,
2469 : nodes, status, flags);
2470 : else
2471 : err = do_pages_stat(mm, nr_pages, pages, status);
2472 :
2473 : mmput(mm);
2474 : return err;
2475 : }
2476 :
2477 : SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
2478 : const void __user * __user *, pages,
2479 : const int __user *, nodes,
2480 : int __user *, status, int, flags)
2481 : {
2482 : return kernel_move_pages(pid, nr_pages, pages, nodes, status, flags);
2483 : }
2484 :
2485 : #ifdef CONFIG_NUMA_BALANCING
2486 : /*
2487 : * Returns true if this is a safe migration target node for misplaced NUMA
2488 : * pages. Currently it only checks the watermarks which is crude.
2489 : */
2490 : static bool migrate_balanced_pgdat(struct pglist_data *pgdat,
2491 : unsigned long nr_migrate_pages)
2492 : {
2493 : int z;
2494 :
2495 : for (z = pgdat->nr_zones - 1; z >= 0; z--) {
2496 : struct zone *zone = pgdat->node_zones + z;
2497 :
2498 : if (!managed_zone(zone))
2499 : continue;
2500 :
2501 : /* Avoid waking kswapd by allocating pages_to_migrate pages. */
2502 : if (!zone_watermark_ok(zone, 0,
2503 : high_wmark_pages(zone) +
2504 : nr_migrate_pages,
2505 : ZONE_MOVABLE, 0))
2506 : continue;
2507 : return true;
2508 : }
2509 : return false;
2510 : }
2511 :
2512 : static struct page *alloc_misplaced_dst_page(struct page *page,
2513 : unsigned long data)
2514 : {
2515 : int nid = (int) data;
2516 : int order = compound_order(page);
2517 : gfp_t gfp = __GFP_THISNODE;
2518 : struct folio *new;
2519 :
2520 : if (order > 0)
2521 : gfp |= GFP_TRANSHUGE_LIGHT;
2522 : else {
2523 : gfp |= GFP_HIGHUSER_MOVABLE | __GFP_NOMEMALLOC | __GFP_NORETRY |
2524 : __GFP_NOWARN;
2525 : gfp &= ~__GFP_RECLAIM;
2526 : }
2527 : new = __folio_alloc_node(gfp, order, nid);
2528 :
2529 : return &new->page;
2530 : }
2531 :
2532 : static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
2533 : {
2534 : int nr_pages = thp_nr_pages(page);
2535 : int order = compound_order(page);
2536 :
2537 : VM_BUG_ON_PAGE(order && !PageTransHuge(page), page);
2538 :
2539 : /* Do not migrate THP mapped by multiple processes */
2540 : if (PageTransHuge(page) && total_mapcount(page) > 1)
2541 : return 0;
2542 :
2543 : /* Avoid migrating to a node that is nearly full */
2544 : if (!migrate_balanced_pgdat(pgdat, nr_pages)) {
2545 : int z;
2546 :
2547 : if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING))
2548 : return 0;
2549 : for (z = pgdat->nr_zones - 1; z >= 0; z--) {
2550 : if (managed_zone(pgdat->node_zones + z))
2551 : break;
2552 : }
2553 : wakeup_kswapd(pgdat->node_zones + z, 0, order, ZONE_MOVABLE);
2554 : return 0;
2555 : }
2556 :
2557 : if (!isolate_lru_page(page))
2558 : return 0;
2559 :
2560 : mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_is_file_lru(page),
2561 : nr_pages);
2562 :
2563 : /*
2564 : * Isolating the page has taken another reference, so the
2565 : * caller's reference can be safely dropped without the page
2566 : * disappearing underneath us during migration.
2567 : */
2568 : put_page(page);
2569 : return 1;
2570 : }
2571 :
2572 : /*
2573 : * Attempt to migrate a misplaced page to the specified destination
2574 : * node. Caller is expected to have an elevated reference count on
2575 : * the page that will be dropped by this function before returning.
2576 : */
2577 : int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
2578 : int node)
2579 : {
2580 : pg_data_t *pgdat = NODE_DATA(node);
2581 : int isolated;
2582 : int nr_remaining;
2583 : unsigned int nr_succeeded;
2584 : LIST_HEAD(migratepages);
2585 : int nr_pages = thp_nr_pages(page);
2586 :
2587 : /*
2588 : * Don't migrate file pages that are mapped in multiple processes
2589 : * with execute permissions as they are probably shared libraries.
2590 : */
2591 : if (page_mapcount(page) != 1 && page_is_file_lru(page) &&
2592 : (vma->vm_flags & VM_EXEC))
2593 : goto out;
2594 :
2595 : /*
2596 : * Also do not migrate dirty pages as not all filesystems can move
2597 : * dirty pages in MIGRATE_ASYNC mode which is a waste of cycles.
2598 : */
2599 : if (page_is_file_lru(page) && PageDirty(page))
2600 : goto out;
2601 :
2602 : isolated = numamigrate_isolate_page(pgdat, page);
2603 : if (!isolated)
2604 : goto out;
2605 :
2606 : list_add(&page->lru, &migratepages);
2607 : nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page,
2608 : NULL, node, MIGRATE_ASYNC,
2609 : MR_NUMA_MISPLACED, &nr_succeeded);
2610 : if (nr_remaining) {
2611 : if (!list_empty(&migratepages)) {
2612 : list_del(&page->lru);
2613 : mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON +
2614 : page_is_file_lru(page), -nr_pages);
2615 : putback_lru_page(page);
2616 : }
2617 : isolated = 0;
2618 : }
2619 : if (nr_succeeded) {
2620 : count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
2621 : if (!node_is_toptier(page_to_nid(page)) && node_is_toptier(node))
2622 : mod_node_page_state(pgdat, PGPROMOTE_SUCCESS,
2623 : nr_succeeded);
2624 : }
2625 : BUG_ON(!list_empty(&migratepages));
2626 : return isolated;
2627 :
2628 : out:
2629 : put_page(page);
2630 : return 0;
2631 : }
2632 : #endif /* CONFIG_NUMA_BALANCING */
2633 : #endif /* CONFIG_NUMA */
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