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