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