| 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | /* |
| 3 | * linux/mm/swap.c |
| 4 | * |
| 5 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
| 6 | */ |
| 7 | |
| 8 | /* |
| 9 | * This file contains the default values for the operation of the |
| 10 | * Linux VM subsystem. Fine-tuning documentation can be found in |
| 11 | * Documentation/admin-guide/sysctl/vm.rst. |
| 12 | * Started 18.12.91 |
| 13 | * Swap aging added 23.2.95, Stephen Tweedie. |
| 14 | * Buffermem limits added 12.3.98, Rik van Riel. |
| 15 | */ |
| 16 | |
| 17 | #include <linux/mm.h> |
| 18 | #include <linux/sched.h> |
| 19 | #include <linux/kernel_stat.h> |
| 20 | #include <linux/swap.h> |
| 21 | #include <linux/mman.h> |
| 22 | #include <linux/pagemap.h> |
| 23 | #include <linux/pagevec.h> |
| 24 | #include <linux/init.h> |
| 25 | #include <linux/export.h> |
| 26 | #include <linux/mm_inline.h> |
| 27 | #include <linux/percpu_counter.h> |
| 28 | #include <linux/memremap.h> |
| 29 | #include <linux/percpu.h> |
| 30 | #include <linux/cpu.h> |
| 31 | #include <linux/notifier.h> |
| 32 | #include <linux/backing-dev.h> |
| 33 | #include <linux/memcontrol.h> |
| 34 | #include <linux/gfp.h> |
| 35 | #include <linux/uio.h> |
| 36 | #include <linux/hugetlb.h> |
| 37 | #include <linux/page_idle.h> |
| 38 | #include <linux/local_lock.h> |
| 39 | #include <linux/buffer_head.h> |
| 40 | |
| 41 | #include "internal.h" |
| 42 | |
| 43 | #define CREATE_TRACE_POINTS |
| 44 | #include <trace/events/pagemap.h> |
| 45 | |
| 46 | /* How many pages do we try to swap or page in/out together? */ |
| 47 | int page_cluster; |
| 48 | |
| 49 | /* Protecting only lru_rotate.pvec which requires disabling interrupts */ |
| 50 | struct lru_rotate { |
| 51 | local_lock_t lock; |
| 52 | struct pagevec pvec; |
| 53 | }; |
| 54 | static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = { |
| 55 | .lock = INIT_LOCAL_LOCK(lock), |
| 56 | }; |
| 57 | |
| 58 | /* |
| 59 | * The following struct pagevec are grouped together because they are protected |
| 60 | * by disabling preemption (and interrupts remain enabled). |
| 61 | */ |
| 62 | struct lru_pvecs { |
| 63 | local_lock_t lock; |
| 64 | struct pagevec lru_add; |
| 65 | struct pagevec lru_deactivate_file; |
| 66 | struct pagevec lru_deactivate; |
| 67 | struct pagevec lru_lazyfree; |
| 68 | #ifdef CONFIG_SMP |
| 69 | struct pagevec activate_page; |
| 70 | #endif |
| 71 | }; |
| 72 | static DEFINE_PER_CPU(struct lru_pvecs, lru_pvecs) = { |
| 73 | .lock = INIT_LOCAL_LOCK(lock), |
| 74 | }; |
| 75 | |
| 76 | /* |
| 77 | * This path almost never happens for VM activity - pages are normally |
| 78 | * freed via pagevecs. But it gets used by networking. |
| 79 | */ |
| 80 | static void __page_cache_release(struct page *page) |
| 81 | { |
| 82 | if (PageLRU(page)) { |
| 83 | struct folio *folio = page_folio(page); |
| 84 | struct lruvec *lruvec; |
| 85 | unsigned long flags; |
| 86 | |
| 87 | lruvec = folio_lruvec_lock_irqsave(folio, &flags); |
| 88 | del_page_from_lru_list(page, lruvec); |
| 89 | __clear_page_lru_flags(page); |
| 90 | unlock_page_lruvec_irqrestore(lruvec, flags); |
| 91 | } |
| 92 | __ClearPageWaiters(page); |
| 93 | } |
| 94 | |
| 95 | static void __put_single_page(struct page *page) |
| 96 | { |
| 97 | __page_cache_release(page); |
| 98 | mem_cgroup_uncharge(page_folio(page)); |
| 99 | free_unref_page(page, 0); |
| 100 | } |
| 101 | |
| 102 | static void __put_compound_page(struct page *page) |
| 103 | { |
| 104 | /* |
| 105 | * __page_cache_release() is supposed to be called for thp, not for |
| 106 | * hugetlb. This is because hugetlb page does never have PageLRU set |
| 107 | * (it's never listed to any LRU lists) and no memcg routines should |
| 108 | * be called for hugetlb (it has a separate hugetlb_cgroup.) |
| 109 | */ |
| 110 | if (!PageHuge(page)) |
| 111 | __page_cache_release(page); |
| 112 | destroy_compound_page(page); |
| 113 | } |
| 114 | |
| 115 | void __put_page(struct page *page) |
| 116 | { |
| 117 | if (is_zone_device_page(page)) { |
| 118 | put_dev_pagemap(page->pgmap); |
| 119 | |
| 120 | /* |
| 121 | * The page belongs to the device that created pgmap. Do |
| 122 | * not return it to page allocator. |
| 123 | */ |
| 124 | return; |
| 125 | } |
| 126 | |
| 127 | if (unlikely(PageCompound(page))) |
| 128 | __put_compound_page(page); |
| 129 | else |
| 130 | __put_single_page(page); |
| 131 | } |
| 132 | EXPORT_SYMBOL(__put_page); |
| 133 | |
| 134 | /** |
| 135 | * put_pages_list() - release a list of pages |
| 136 | * @pages: list of pages threaded on page->lru |
| 137 | * |
| 138 | * Release a list of pages which are strung together on page.lru. |
| 139 | */ |
| 140 | void put_pages_list(struct list_head *pages) |
| 141 | { |
| 142 | struct page *page, *next; |
| 143 | |
| 144 | list_for_each_entry_safe(page, next, pages, lru) { |
| 145 | if (!put_page_testzero(page)) { |
| 146 | list_del(&page->lru); |
| 147 | continue; |
| 148 | } |
| 149 | if (PageHead(page)) { |
| 150 | list_del(&page->lru); |
| 151 | __put_compound_page(page); |
| 152 | continue; |
| 153 | } |
| 154 | /* Cannot be PageLRU because it's passed to us using the lru */ |
| 155 | __ClearPageWaiters(page); |
| 156 | } |
| 157 | |
| 158 | free_unref_page_list(pages); |
| 159 | INIT_LIST_HEAD(pages); |
| 160 | } |
| 161 | EXPORT_SYMBOL(put_pages_list); |
| 162 | |
| 163 | /* |
| 164 | * get_kernel_pages() - pin kernel pages in memory |
| 165 | * @kiov: An array of struct kvec structures |
| 166 | * @nr_segs: number of segments to pin |
| 167 | * @write: pinning for read/write, currently ignored |
| 168 | * @pages: array that receives pointers to the pages pinned. |
| 169 | * Should be at least nr_segs long. |
| 170 | * |
| 171 | * Returns number of pages pinned. This may be fewer than the number |
| 172 | * requested. If nr_pages is 0 or negative, returns 0. If no pages |
| 173 | * were pinned, returns -errno. Each page returned must be released |
| 174 | * with a put_page() call when it is finished with. |
| 175 | */ |
| 176 | int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write, |
| 177 | struct page **pages) |
| 178 | { |
| 179 | int seg; |
| 180 | |
| 181 | for (seg = 0; seg < nr_segs; seg++) { |
| 182 | if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE)) |
| 183 | return seg; |
| 184 | |
| 185 | pages[seg] = kmap_to_page(kiov[seg].iov_base); |
| 186 | get_page(pages[seg]); |
| 187 | } |
| 188 | |
| 189 | return seg; |
| 190 | } |
| 191 | EXPORT_SYMBOL_GPL(get_kernel_pages); |
| 192 | |
| 193 | static void pagevec_lru_move_fn(struct pagevec *pvec, |
| 194 | void (*move_fn)(struct page *page, struct lruvec *lruvec)) |
| 195 | { |
| 196 | int i; |
| 197 | struct lruvec *lruvec = NULL; |
| 198 | unsigned long flags = 0; |
| 199 | |
| 200 | for (i = 0; i < pagevec_count(pvec); i++) { |
| 201 | struct page *page = pvec->pages[i]; |
| 202 | struct folio *folio = page_folio(page); |
| 203 | |
| 204 | /* block memcg migration during page moving between lru */ |
| 205 | if (!TestClearPageLRU(page)) |
| 206 | continue; |
| 207 | |
| 208 | lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags); |
| 209 | (*move_fn)(page, lruvec); |
| 210 | |
| 211 | SetPageLRU(page); |
| 212 | } |
| 213 | if (lruvec) |
| 214 | unlock_page_lruvec_irqrestore(lruvec, flags); |
| 215 | release_pages(pvec->pages, pvec->nr); |
| 216 | pagevec_reinit(pvec); |
| 217 | } |
| 218 | |
| 219 | static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec) |
| 220 | { |
| 221 | struct folio *folio = page_folio(page); |
| 222 | |
| 223 | if (!folio_test_unevictable(folio)) { |
| 224 | lruvec_del_folio(lruvec, folio); |
| 225 | folio_clear_active(folio); |
| 226 | lruvec_add_folio_tail(lruvec, folio); |
| 227 | __count_vm_events(PGROTATED, folio_nr_pages(folio)); |
| 228 | } |
| 229 | } |
| 230 | |
| 231 | /* return true if pagevec needs to drain */ |
| 232 | static bool pagevec_add_and_need_flush(struct pagevec *pvec, struct page *page) |
| 233 | { |
| 234 | bool ret = false; |
| 235 | |
| 236 | if (!pagevec_add(pvec, page) || PageCompound(page) || |
| 237 | lru_cache_disabled()) |
| 238 | ret = true; |
| 239 | |
| 240 | return ret; |
| 241 | } |
| 242 | |
| 243 | /* |
| 244 | * Writeback is about to end against a folio which has been marked for |
| 245 | * immediate reclaim. If it still appears to be reclaimable, move it |
| 246 | * to the tail of the inactive list. |
| 247 | * |
| 248 | * folio_rotate_reclaimable() must disable IRQs, to prevent nasty races. |
| 249 | */ |
| 250 | void folio_rotate_reclaimable(struct folio *folio) |
| 251 | { |
| 252 | if (!folio_test_locked(folio) && !folio_test_dirty(folio) && |
| 253 | !folio_test_unevictable(folio) && folio_test_lru(folio)) { |
| 254 | struct pagevec *pvec; |
| 255 | unsigned long flags; |
| 256 | |
| 257 | folio_get(folio); |
| 258 | local_lock_irqsave(&lru_rotate.lock, flags); |
| 259 | pvec = this_cpu_ptr(&lru_rotate.pvec); |
| 260 | if (pagevec_add_and_need_flush(pvec, &folio->page)) |
| 261 | pagevec_lru_move_fn(pvec, pagevec_move_tail_fn); |
| 262 | local_unlock_irqrestore(&lru_rotate.lock, flags); |
| 263 | } |
| 264 | } |
| 265 | |
| 266 | void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages) |
| 267 | { |
| 268 | do { |
| 269 | unsigned long lrusize; |
| 270 | |
| 271 | /* |
| 272 | * Hold lruvec->lru_lock is safe here, since |
| 273 | * 1) The pinned lruvec in reclaim, or |
| 274 | * 2) From a pre-LRU page during refault (which also holds the |
| 275 | * rcu lock, so would be safe even if the page was on the LRU |
| 276 | * and could move simultaneously to a new lruvec). |
| 277 | */ |
| 278 | spin_lock_irq(&lruvec->lru_lock); |
| 279 | /* Record cost event */ |
| 280 | if (file) |
| 281 | lruvec->file_cost += nr_pages; |
| 282 | else |
| 283 | lruvec->anon_cost += nr_pages; |
| 284 | |
| 285 | /* |
| 286 | * Decay previous events |
| 287 | * |
| 288 | * Because workloads change over time (and to avoid |
| 289 | * overflow) we keep these statistics as a floating |
| 290 | * average, which ends up weighing recent refaults |
| 291 | * more than old ones. |
| 292 | */ |
| 293 | lrusize = lruvec_page_state(lruvec, NR_INACTIVE_ANON) + |
| 294 | lruvec_page_state(lruvec, NR_ACTIVE_ANON) + |
| 295 | lruvec_page_state(lruvec, NR_INACTIVE_FILE) + |
| 296 | lruvec_page_state(lruvec, NR_ACTIVE_FILE); |
| 297 | |
| 298 | if (lruvec->file_cost + lruvec->anon_cost > lrusize / 4) { |
| 299 | lruvec->file_cost /= 2; |
| 300 | lruvec->anon_cost /= 2; |
| 301 | } |
| 302 | spin_unlock_irq(&lruvec->lru_lock); |
| 303 | } while ((lruvec = parent_lruvec(lruvec))); |
| 304 | } |
| 305 | |
| 306 | void lru_note_cost_folio(struct folio *folio) |
| 307 | { |
| 308 | lru_note_cost(folio_lruvec(folio), folio_is_file_lru(folio), |
| 309 | folio_nr_pages(folio)); |
| 310 | } |
| 311 | |
| 312 | static void __folio_activate(struct folio *folio, struct lruvec *lruvec) |
| 313 | { |
| 314 | if (!folio_test_active(folio) && !folio_test_unevictable(folio)) { |
| 315 | long nr_pages = folio_nr_pages(folio); |
| 316 | |
| 317 | lruvec_del_folio(lruvec, folio); |
| 318 | folio_set_active(folio); |
| 319 | lruvec_add_folio(lruvec, folio); |
| 320 | trace_mm_lru_activate(folio); |
| 321 | |
| 322 | __count_vm_events(PGACTIVATE, nr_pages); |
| 323 | __count_memcg_events(lruvec_memcg(lruvec), PGACTIVATE, |
| 324 | nr_pages); |
| 325 | } |
| 326 | } |
| 327 | |
| 328 | #ifdef CONFIG_SMP |
| 329 | static void __activate_page(struct page *page, struct lruvec *lruvec) |
| 330 | { |
| 331 | return __folio_activate(page_folio(page), lruvec); |
| 332 | } |
| 333 | |
| 334 | static void activate_page_drain(int cpu) |
| 335 | { |
| 336 | struct pagevec *pvec = &per_cpu(lru_pvecs.activate_page, cpu); |
| 337 | |
| 338 | if (pagevec_count(pvec)) |
| 339 | pagevec_lru_move_fn(pvec, __activate_page); |
| 340 | } |
| 341 | |
| 342 | static bool need_activate_page_drain(int cpu) |
| 343 | { |
| 344 | return pagevec_count(&per_cpu(lru_pvecs.activate_page, cpu)) != 0; |
| 345 | } |
| 346 | |
| 347 | static void folio_activate(struct folio *folio) |
| 348 | { |
| 349 | if (folio_test_lru(folio) && !folio_test_active(folio) && |
| 350 | !folio_test_unevictable(folio)) { |
| 351 | struct pagevec *pvec; |
| 352 | |
| 353 | folio_get(folio); |
| 354 | local_lock(&lru_pvecs.lock); |
| 355 | pvec = this_cpu_ptr(&lru_pvecs.activate_page); |
| 356 | if (pagevec_add_and_need_flush(pvec, &folio->page)) |
| 357 | pagevec_lru_move_fn(pvec, __activate_page); |
| 358 | local_unlock(&lru_pvecs.lock); |
| 359 | } |
| 360 | } |
| 361 | |
| 362 | #else |
| 363 | static inline void activate_page_drain(int cpu) |
| 364 | { |
| 365 | } |
| 366 | |
| 367 | static void folio_activate(struct folio *folio) |
| 368 | { |
| 369 | struct lruvec *lruvec; |
| 370 | |
| 371 | if (folio_test_clear_lru(folio)) { |
| 372 | lruvec = folio_lruvec_lock_irq(folio); |
| 373 | __folio_activate(folio, lruvec); |
| 374 | unlock_page_lruvec_irq(lruvec); |
| 375 | folio_set_lru(folio); |
| 376 | } |
| 377 | } |
| 378 | #endif |
| 379 | |
| 380 | static void __lru_cache_activate_folio(struct folio *folio) |
| 381 | { |
| 382 | struct pagevec *pvec; |
| 383 | int i; |
| 384 | |
| 385 | local_lock(&lru_pvecs.lock); |
| 386 | pvec = this_cpu_ptr(&lru_pvecs.lru_add); |
| 387 | |
| 388 | /* |
| 389 | * Search backwards on the optimistic assumption that the page being |
| 390 | * activated has just been added to this pagevec. Note that only |
| 391 | * the local pagevec is examined as a !PageLRU page could be in the |
| 392 | * process of being released, reclaimed, migrated or on a remote |
| 393 | * pagevec that is currently being drained. Furthermore, marking |
| 394 | * a remote pagevec's page PageActive potentially hits a race where |
| 395 | * a page is marked PageActive just after it is added to the inactive |
| 396 | * list causing accounting errors and BUG_ON checks to trigger. |
| 397 | */ |
| 398 | for (i = pagevec_count(pvec) - 1; i >= 0; i--) { |
| 399 | struct page *pagevec_page = pvec->pages[i]; |
| 400 | |
| 401 | if (pagevec_page == &folio->page) { |
| 402 | folio_set_active(folio); |
| 403 | break; |
| 404 | } |
| 405 | } |
| 406 | |
| 407 | local_unlock(&lru_pvecs.lock); |
| 408 | } |
| 409 | |
| 410 | /* |
| 411 | * Mark a page as having seen activity. |
| 412 | * |
| 413 | * inactive,unreferenced -> inactive,referenced |
| 414 | * inactive,referenced -> active,unreferenced |
| 415 | * active,unreferenced -> active,referenced |
| 416 | * |
| 417 | * When a newly allocated page is not yet visible, so safe for non-atomic ops, |
| 418 | * __SetPageReferenced(page) may be substituted for mark_page_accessed(page). |
| 419 | */ |
| 420 | void folio_mark_accessed(struct folio *folio) |
| 421 | { |
| 422 | if (!folio_test_referenced(folio)) { |
| 423 | folio_set_referenced(folio); |
| 424 | } else if (folio_test_unevictable(folio)) { |
| 425 | /* |
| 426 | * Unevictable pages are on the "LRU_UNEVICTABLE" list. But, |
| 427 | * this list is never rotated or maintained, so marking an |
| 428 | * evictable page accessed has no effect. |
| 429 | */ |
| 430 | } else if (!folio_test_active(folio)) { |
| 431 | /* |
| 432 | * If the page is on the LRU, queue it for activation via |
| 433 | * lru_pvecs.activate_page. Otherwise, assume the page is on a |
| 434 | * pagevec, mark it active and it'll be moved to the active |
| 435 | * LRU on the next drain. |
| 436 | */ |
| 437 | if (folio_test_lru(folio)) |
| 438 | folio_activate(folio); |
| 439 | else |
| 440 | __lru_cache_activate_folio(folio); |
| 441 | folio_clear_referenced(folio); |
| 442 | workingset_activation(folio); |
| 443 | } |
| 444 | if (folio_test_idle(folio)) |
| 445 | folio_clear_idle(folio); |
| 446 | } |
| 447 | EXPORT_SYMBOL(folio_mark_accessed); |
| 448 | |
| 449 | /** |
| 450 | * folio_add_lru - Add a folio to an LRU list. |
| 451 | * @folio: The folio to be added to the LRU. |
| 452 | * |
| 453 | * Queue the folio for addition to the LRU. The decision on whether |
| 454 | * to add the page to the [in]active [file|anon] list is deferred until the |
| 455 | * pagevec is drained. This gives a chance for the caller of folio_add_lru() |
| 456 | * have the folio added to the active list using folio_mark_accessed(). |
| 457 | */ |
| 458 | void folio_add_lru(struct folio *folio) |
| 459 | { |
| 460 | struct pagevec *pvec; |
| 461 | |
| 462 | VM_BUG_ON_FOLIO(folio_test_active(folio) && folio_test_unevictable(folio), folio); |
| 463 | VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); |
| 464 | |
| 465 | folio_get(folio); |
| 466 | local_lock(&lru_pvecs.lock); |
| 467 | pvec = this_cpu_ptr(&lru_pvecs.lru_add); |
| 468 | if (pagevec_add_and_need_flush(pvec, &folio->page)) |
| 469 | __pagevec_lru_add(pvec); |
| 470 | local_unlock(&lru_pvecs.lock); |
| 471 | } |
| 472 | EXPORT_SYMBOL(folio_add_lru); |
| 473 | |
| 474 | /** |
| 475 | * lru_cache_add_inactive_or_unevictable |
| 476 | * @page: the page to be added to LRU |
| 477 | * @vma: vma in which page is mapped for determining reclaimability |
| 478 | * |
| 479 | * Place @page on the inactive or unevictable LRU list, depending on its |
| 480 | * evictability. |
| 481 | */ |
| 482 | void lru_cache_add_inactive_or_unevictable(struct page *page, |
| 483 | struct vm_area_struct *vma) |
| 484 | { |
| 485 | bool unevictable; |
| 486 | |
| 487 | VM_BUG_ON_PAGE(PageLRU(page), page); |
| 488 | |
| 489 | unevictable = (vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) == VM_LOCKED; |
| 490 | if (unlikely(unevictable) && !TestSetPageMlocked(page)) { |
| 491 | int nr_pages = thp_nr_pages(page); |
| 492 | /* |
| 493 | * We use the irq-unsafe __mod_zone_page_state because this |
| 494 | * counter is not modified from interrupt context, and the pte |
| 495 | * lock is held(spinlock), which implies preemption disabled. |
| 496 | */ |
| 497 | __mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages); |
| 498 | count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages); |
| 499 | } |
| 500 | lru_cache_add(page); |
| 501 | } |
| 502 | |
| 503 | /* |
| 504 | * If the page can not be invalidated, it is moved to the |
| 505 | * inactive list to speed up its reclaim. It is moved to the |
| 506 | * head of the list, rather than the tail, to give the flusher |
| 507 | * threads some time to write it out, as this is much more |
| 508 | * effective than the single-page writeout from reclaim. |
| 509 | * |
| 510 | * If the page isn't page_mapped and dirty/writeback, the page |
| 511 | * could reclaim asap using PG_reclaim. |
| 512 | * |
| 513 | * 1. active, mapped page -> none |
| 514 | * 2. active, dirty/writeback page -> inactive, head, PG_reclaim |
| 515 | * 3. inactive, mapped page -> none |
| 516 | * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim |
| 517 | * 5. inactive, clean -> inactive, tail |
| 518 | * 6. Others -> none |
| 519 | * |
| 520 | * In 4, why it moves inactive's head, the VM expects the page would |
| 521 | * be write it out by flusher threads as this is much more effective |
| 522 | * than the single-page writeout from reclaim. |
| 523 | */ |
| 524 | static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec) |
| 525 | { |
| 526 | bool active = PageActive(page); |
| 527 | int nr_pages = thp_nr_pages(page); |
| 528 | |
| 529 | if (PageUnevictable(page)) |
| 530 | return; |
| 531 | |
| 532 | /* Some processes are using the page */ |
| 533 | if (page_mapped(page)) |
| 534 | return; |
| 535 | |
| 536 | del_page_from_lru_list(page, lruvec); |
| 537 | ClearPageActive(page); |
| 538 | ClearPageReferenced(page); |
| 539 | |
| 540 | if (PageWriteback(page) || PageDirty(page)) { |
| 541 | /* |
| 542 | * PG_reclaim could be raced with end_page_writeback |
| 543 | * It can make readahead confusing. But race window |
| 544 | * is _really_ small and it's non-critical problem. |
| 545 | */ |
| 546 | add_page_to_lru_list(page, lruvec); |
| 547 | SetPageReclaim(page); |
| 548 | } else { |
| 549 | /* |
| 550 | * The page's writeback ends up during pagevec |
| 551 | * We move that page into tail of inactive. |
| 552 | */ |
| 553 | add_page_to_lru_list_tail(page, lruvec); |
| 554 | __count_vm_events(PGROTATED, nr_pages); |
| 555 | } |
| 556 | |
| 557 | if (active) { |
| 558 | __count_vm_events(PGDEACTIVATE, nr_pages); |
| 559 | __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, |
| 560 | nr_pages); |
| 561 | } |
| 562 | } |
| 563 | |
| 564 | static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec) |
| 565 | { |
| 566 | if (PageActive(page) && !PageUnevictable(page)) { |
| 567 | int nr_pages = thp_nr_pages(page); |
| 568 | |
| 569 | del_page_from_lru_list(page, lruvec); |
| 570 | ClearPageActive(page); |
| 571 | ClearPageReferenced(page); |
| 572 | add_page_to_lru_list(page, lruvec); |
| 573 | |
| 574 | __count_vm_events(PGDEACTIVATE, nr_pages); |
| 575 | __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, |
| 576 | nr_pages); |
| 577 | } |
| 578 | } |
| 579 | |
| 580 | static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec) |
| 581 | { |
| 582 | if (PageAnon(page) && PageSwapBacked(page) && |
| 583 | !PageSwapCache(page) && !PageUnevictable(page)) { |
| 584 | int nr_pages = thp_nr_pages(page); |
| 585 | |
| 586 | del_page_from_lru_list(page, lruvec); |
| 587 | ClearPageActive(page); |
| 588 | ClearPageReferenced(page); |
| 589 | /* |
| 590 | * Lazyfree pages are clean anonymous pages. They have |
| 591 | * PG_swapbacked flag cleared, to distinguish them from normal |
| 592 | * anonymous pages |
| 593 | */ |
| 594 | ClearPageSwapBacked(page); |
| 595 | add_page_to_lru_list(page, lruvec); |
| 596 | |
| 597 | __count_vm_events(PGLAZYFREE, nr_pages); |
| 598 | __count_memcg_events(lruvec_memcg(lruvec), PGLAZYFREE, |
| 599 | nr_pages); |
| 600 | } |
| 601 | } |
| 602 | |
| 603 | /* |
| 604 | * Drain pages out of the cpu's pagevecs. |
| 605 | * Either "cpu" is the current CPU, and preemption has already been |
| 606 | * disabled; or "cpu" is being hot-unplugged, and is already dead. |
| 607 | */ |
| 608 | void lru_add_drain_cpu(int cpu) |
| 609 | { |
| 610 | struct pagevec *pvec = &per_cpu(lru_pvecs.lru_add, cpu); |
| 611 | |
| 612 | if (pagevec_count(pvec)) |
| 613 | __pagevec_lru_add(pvec); |
| 614 | |
| 615 | pvec = &per_cpu(lru_rotate.pvec, cpu); |
| 616 | /* Disabling interrupts below acts as a compiler barrier. */ |
| 617 | if (data_race(pagevec_count(pvec))) { |
| 618 | unsigned long flags; |
| 619 | |
| 620 | /* No harm done if a racing interrupt already did this */ |
| 621 | local_lock_irqsave(&lru_rotate.lock, flags); |
| 622 | pagevec_lru_move_fn(pvec, pagevec_move_tail_fn); |
| 623 | local_unlock_irqrestore(&lru_rotate.lock, flags); |
| 624 | } |
| 625 | |
| 626 | pvec = &per_cpu(lru_pvecs.lru_deactivate_file, cpu); |
| 627 | if (pagevec_count(pvec)) |
| 628 | pagevec_lru_move_fn(pvec, lru_deactivate_file_fn); |
| 629 | |
| 630 | pvec = &per_cpu(lru_pvecs.lru_deactivate, cpu); |
| 631 | if (pagevec_count(pvec)) |
| 632 | pagevec_lru_move_fn(pvec, lru_deactivate_fn); |
| 633 | |
| 634 | pvec = &per_cpu(lru_pvecs.lru_lazyfree, cpu); |
| 635 | if (pagevec_count(pvec)) |
| 636 | pagevec_lru_move_fn(pvec, lru_lazyfree_fn); |
| 637 | |
| 638 | activate_page_drain(cpu); |
| 639 | } |
| 640 | |
| 641 | /** |
| 642 | * deactivate_file_page - forcefully deactivate a file page |
| 643 | * @page: page to deactivate |
| 644 | * |
| 645 | * This function hints the VM that @page is a good reclaim candidate, |
| 646 | * for example if its invalidation fails due to the page being dirty |
| 647 | * or under writeback. |
| 648 | */ |
| 649 | void deactivate_file_page(struct page *page) |
| 650 | { |
| 651 | /* |
| 652 | * In a workload with many unevictable page such as mprotect, |
| 653 | * unevictable page deactivation for accelerating reclaim is pointless. |
| 654 | */ |
| 655 | if (PageUnevictable(page)) |
| 656 | return; |
| 657 | |
| 658 | if (likely(get_page_unless_zero(page))) { |
| 659 | struct pagevec *pvec; |
| 660 | |
| 661 | local_lock(&lru_pvecs.lock); |
| 662 | pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate_file); |
| 663 | |
| 664 | if (pagevec_add_and_need_flush(pvec, page)) |
| 665 | pagevec_lru_move_fn(pvec, lru_deactivate_file_fn); |
| 666 | local_unlock(&lru_pvecs.lock); |
| 667 | } |
| 668 | } |
| 669 | |
| 670 | /* |
| 671 | * deactivate_page - deactivate a page |
| 672 | * @page: page to deactivate |
| 673 | * |
| 674 | * deactivate_page() moves @page to the inactive list if @page was on the active |
| 675 | * list and was not an unevictable page. This is done to accelerate the reclaim |
| 676 | * of @page. |
| 677 | */ |
| 678 | void deactivate_page(struct page *page) |
| 679 | { |
| 680 | if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) { |
| 681 | struct pagevec *pvec; |
| 682 | |
| 683 | local_lock(&lru_pvecs.lock); |
| 684 | pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate); |
| 685 | get_page(page); |
| 686 | if (pagevec_add_and_need_flush(pvec, page)) |
| 687 | pagevec_lru_move_fn(pvec, lru_deactivate_fn); |
| 688 | local_unlock(&lru_pvecs.lock); |
| 689 | } |
| 690 | } |
| 691 | |
| 692 | /** |
| 693 | * mark_page_lazyfree - make an anon page lazyfree |
| 694 | * @page: page to deactivate |
| 695 | * |
| 696 | * mark_page_lazyfree() moves @page to the inactive file list. |
| 697 | * This is done to accelerate the reclaim of @page. |
| 698 | */ |
| 699 | void mark_page_lazyfree(struct page *page) |
| 700 | { |
| 701 | if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) && |
| 702 | !PageSwapCache(page) && !PageUnevictable(page)) { |
| 703 | struct pagevec *pvec; |
| 704 | |
| 705 | local_lock(&lru_pvecs.lock); |
| 706 | pvec = this_cpu_ptr(&lru_pvecs.lru_lazyfree); |
| 707 | get_page(page); |
| 708 | if (pagevec_add_and_need_flush(pvec, page)) |
| 709 | pagevec_lru_move_fn(pvec, lru_lazyfree_fn); |
| 710 | local_unlock(&lru_pvecs.lock); |
| 711 | } |
| 712 | } |
| 713 | |
| 714 | void lru_add_drain(void) |
| 715 | { |
| 716 | local_lock(&lru_pvecs.lock); |
| 717 | lru_add_drain_cpu(smp_processor_id()); |
| 718 | local_unlock(&lru_pvecs.lock); |
| 719 | } |
| 720 | |
| 721 | /* |
| 722 | * It's called from per-cpu workqueue context in SMP case so |
| 723 | * lru_add_drain_cpu and invalidate_bh_lrus_cpu should run on |
| 724 | * the same cpu. It shouldn't be a problem in !SMP case since |
| 725 | * the core is only one and the locks will disable preemption. |
| 726 | */ |
| 727 | static void lru_add_and_bh_lrus_drain(void) |
| 728 | { |
| 729 | local_lock(&lru_pvecs.lock); |
| 730 | lru_add_drain_cpu(smp_processor_id()); |
| 731 | local_unlock(&lru_pvecs.lock); |
| 732 | invalidate_bh_lrus_cpu(); |
| 733 | } |
| 734 | |
| 735 | void lru_add_drain_cpu_zone(struct zone *zone) |
| 736 | { |
| 737 | local_lock(&lru_pvecs.lock); |
| 738 | lru_add_drain_cpu(smp_processor_id()); |
| 739 | drain_local_pages(zone); |
| 740 | local_unlock(&lru_pvecs.lock); |
| 741 | } |
| 742 | |
| 743 | #ifdef CONFIG_SMP |
| 744 | |
| 745 | static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work); |
| 746 | |
| 747 | static void lru_add_drain_per_cpu(struct work_struct *dummy) |
| 748 | { |
| 749 | lru_add_and_bh_lrus_drain(); |
| 750 | } |
| 751 | |
| 752 | /* |
| 753 | * Doesn't need any cpu hotplug locking because we do rely on per-cpu |
| 754 | * kworkers being shut down before our page_alloc_cpu_dead callback is |
| 755 | * executed on the offlined cpu. |
| 756 | * Calling this function with cpu hotplug locks held can actually lead |
| 757 | * to obscure indirect dependencies via WQ context. |
| 758 | */ |
| 759 | inline void __lru_add_drain_all(bool force_all_cpus) |
| 760 | { |
| 761 | /* |
| 762 | * lru_drain_gen - Global pages generation number |
| 763 | * |
| 764 | * (A) Definition: global lru_drain_gen = x implies that all generations |
| 765 | * 0 < n <= x are already *scheduled* for draining. |
| 766 | * |
| 767 | * This is an optimization for the highly-contended use case where a |
| 768 | * user space workload keeps constantly generating a flow of pages for |
| 769 | * each CPU. |
| 770 | */ |
| 771 | static unsigned int lru_drain_gen; |
| 772 | static struct cpumask has_work; |
| 773 | static DEFINE_MUTEX(lock); |
| 774 | unsigned cpu, this_gen; |
| 775 | |
| 776 | /* |
| 777 | * Make sure nobody triggers this path before mm_percpu_wq is fully |
| 778 | * initialized. |
| 779 | */ |
| 780 | if (WARN_ON(!mm_percpu_wq)) |
| 781 | return; |
| 782 | |
| 783 | /* |
| 784 | * Guarantee pagevec counter stores visible by this CPU are visible to |
| 785 | * other CPUs before loading the current drain generation. |
| 786 | */ |
| 787 | smp_mb(); |
| 788 | |
| 789 | /* |
| 790 | * (B) Locally cache global LRU draining generation number |
| 791 | * |
| 792 | * The read barrier ensures that the counter is loaded before the mutex |
| 793 | * is taken. It pairs with smp_mb() inside the mutex critical section |
| 794 | * at (D). |
| 795 | */ |
| 796 | this_gen = smp_load_acquire(&lru_drain_gen); |
| 797 | |
| 798 | mutex_lock(&lock); |
| 799 | |
| 800 | /* |
| 801 | * (C) Exit the draining operation if a newer generation, from another |
| 802 | * lru_add_drain_all(), was already scheduled for draining. Check (A). |
| 803 | */ |
| 804 | if (unlikely(this_gen != lru_drain_gen && !force_all_cpus)) |
| 805 | goto done; |
| 806 | |
| 807 | /* |
| 808 | * (D) Increment global generation number |
| 809 | * |
| 810 | * Pairs with smp_load_acquire() at (B), outside of the critical |
| 811 | * section. Use a full memory barrier to guarantee that the new global |
| 812 | * drain generation number is stored before loading pagevec counters. |
| 813 | * |
| 814 | * This pairing must be done here, before the for_each_online_cpu loop |
| 815 | * below which drains the page vectors. |
| 816 | * |
| 817 | * Let x, y, and z represent some system CPU numbers, where x < y < z. |
| 818 | * Assume CPU #z is in the middle of the for_each_online_cpu loop |
| 819 | * below and has already reached CPU #y's per-cpu data. CPU #x comes |
| 820 | * along, adds some pages to its per-cpu vectors, then calls |
| 821 | * lru_add_drain_all(). |
| 822 | * |
| 823 | * If the paired barrier is done at any later step, e.g. after the |
| 824 | * loop, CPU #x will just exit at (C) and miss flushing out all of its |
| 825 | * added pages. |
| 826 | */ |
| 827 | WRITE_ONCE(lru_drain_gen, lru_drain_gen + 1); |
| 828 | smp_mb(); |
| 829 | |
| 830 | cpumask_clear(&has_work); |
| 831 | for_each_online_cpu(cpu) { |
| 832 | struct work_struct *work = &per_cpu(lru_add_drain_work, cpu); |
| 833 | |
| 834 | if (force_all_cpus || |
| 835 | pagevec_count(&per_cpu(lru_pvecs.lru_add, cpu)) || |
| 836 | data_race(pagevec_count(&per_cpu(lru_rotate.pvec, cpu))) || |
| 837 | pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) || |
| 838 | pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, cpu)) || |
| 839 | pagevec_count(&per_cpu(lru_pvecs.lru_lazyfree, cpu)) || |
| 840 | need_activate_page_drain(cpu) || |
| 841 | has_bh_in_lru(cpu, NULL)) { |
| 842 | INIT_WORK(work, lru_add_drain_per_cpu); |
| 843 | queue_work_on(cpu, mm_percpu_wq, work); |
| 844 | __cpumask_set_cpu(cpu, &has_work); |
| 845 | } |
| 846 | } |
| 847 | |
| 848 | for_each_cpu(cpu, &has_work) |
| 849 | flush_work(&per_cpu(lru_add_drain_work, cpu)); |
| 850 | |
| 851 | done: |
| 852 | mutex_unlock(&lock); |
| 853 | } |
| 854 | |
| 855 | void lru_add_drain_all(void) |
| 856 | { |
| 857 | __lru_add_drain_all(false); |
| 858 | } |
| 859 | #else |
| 860 | void lru_add_drain_all(void) |
| 861 | { |
| 862 | lru_add_drain(); |
| 863 | } |
| 864 | #endif /* CONFIG_SMP */ |
| 865 | |
| 866 | atomic_t lru_disable_count = ATOMIC_INIT(0); |
| 867 | |
| 868 | /* |
| 869 | * lru_cache_disable() needs to be called before we start compiling |
| 870 | * a list of pages to be migrated using isolate_lru_page(). |
| 871 | * It drains pages on LRU cache and then disable on all cpus until |
| 872 | * lru_cache_enable is called. |
| 873 | * |
| 874 | * Must be paired with a call to lru_cache_enable(). |
| 875 | */ |
| 876 | void lru_cache_disable(void) |
| 877 | { |
| 878 | atomic_inc(&lru_disable_count); |
| 879 | #ifdef CONFIG_SMP |
| 880 | /* |
| 881 | * lru_add_drain_all in the force mode will schedule draining on |
| 882 | * all online CPUs so any calls of lru_cache_disabled wrapped by |
| 883 | * local_lock or preemption disabled would be ordered by that. |
| 884 | * The atomic operation doesn't need to have stronger ordering |
| 885 | * requirements because that is enforced by the scheduling |
| 886 | * guarantees. |
| 887 | */ |
| 888 | __lru_add_drain_all(true); |
| 889 | #else |
| 890 | lru_add_and_bh_lrus_drain(); |
| 891 | #endif |
| 892 | } |
| 893 | |
| 894 | /** |
| 895 | * release_pages - batched put_page() |
| 896 | * @pages: array of pages to release |
| 897 | * @nr: number of pages |
| 898 | * |
| 899 | * Decrement the reference count on all the pages in @pages. If it |
| 900 | * fell to zero, remove the page from the LRU and free it. |
| 901 | */ |
| 902 | void release_pages(struct page **pages, int nr) |
| 903 | { |
| 904 | int i; |
| 905 | LIST_HEAD(pages_to_free); |
| 906 | struct lruvec *lruvec = NULL; |
| 907 | unsigned long flags = 0; |
| 908 | unsigned int lock_batch; |
| 909 | |
| 910 | for (i = 0; i < nr; i++) { |
| 911 | struct page *page = pages[i]; |
| 912 | struct folio *folio = page_folio(page); |
| 913 | |
| 914 | /* |
| 915 | * Make sure the IRQ-safe lock-holding time does not get |
| 916 | * excessive with a continuous string of pages from the |
| 917 | * same lruvec. The lock is held only if lruvec != NULL. |
| 918 | */ |
| 919 | if (lruvec && ++lock_batch == SWAP_CLUSTER_MAX) { |
| 920 | unlock_page_lruvec_irqrestore(lruvec, flags); |
| 921 | lruvec = NULL; |
| 922 | } |
| 923 | |
| 924 | page = &folio->page; |
| 925 | if (is_huge_zero_page(page)) |
| 926 | continue; |
| 927 | |
| 928 | if (is_zone_device_page(page)) { |
| 929 | if (lruvec) { |
| 930 | unlock_page_lruvec_irqrestore(lruvec, flags); |
| 931 | lruvec = NULL; |
| 932 | } |
| 933 | /* |
| 934 | * ZONE_DEVICE pages that return 'false' from |
| 935 | * page_is_devmap_managed() do not require special |
| 936 | * processing, and instead, expect a call to |
| 937 | * put_page_testzero(). |
| 938 | */ |
| 939 | if (page_is_devmap_managed(page)) { |
| 940 | put_devmap_managed_page(page); |
| 941 | continue; |
| 942 | } |
| 943 | if (put_page_testzero(page)) |
| 944 | put_dev_pagemap(page->pgmap); |
| 945 | continue; |
| 946 | } |
| 947 | |
| 948 | if (!put_page_testzero(page)) |
| 949 | continue; |
| 950 | |
| 951 | if (PageCompound(page)) { |
| 952 | if (lruvec) { |
| 953 | unlock_page_lruvec_irqrestore(lruvec, flags); |
| 954 | lruvec = NULL; |
| 955 | } |
| 956 | __put_compound_page(page); |
| 957 | continue; |
| 958 | } |
| 959 | |
| 960 | if (PageLRU(page)) { |
| 961 | struct lruvec *prev_lruvec = lruvec; |
| 962 | |
| 963 | lruvec = folio_lruvec_relock_irqsave(folio, lruvec, |
| 964 | &flags); |
| 965 | if (prev_lruvec != lruvec) |
| 966 | lock_batch = 0; |
| 967 | |
| 968 | del_page_from_lru_list(page, lruvec); |
| 969 | __clear_page_lru_flags(page); |
| 970 | } |
| 971 | |
| 972 | __ClearPageWaiters(page); |
| 973 | |
| 974 | list_add(&page->lru, &pages_to_free); |
| 975 | } |
| 976 | if (lruvec) |
| 977 | unlock_page_lruvec_irqrestore(lruvec, flags); |
| 978 | |
| 979 | mem_cgroup_uncharge_list(&pages_to_free); |
| 980 | free_unref_page_list(&pages_to_free); |
| 981 | } |
| 982 | EXPORT_SYMBOL(release_pages); |
| 983 | |
| 984 | /* |
| 985 | * The pages which we're about to release may be in the deferred lru-addition |
| 986 | * queues. That would prevent them from really being freed right now. That's |
| 987 | * OK from a correctness point of view but is inefficient - those pages may be |
| 988 | * cache-warm and we want to give them back to the page allocator ASAP. |
| 989 | * |
| 990 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() |
| 991 | * and __pagevec_lru_add_active() call release_pages() directly to avoid |
| 992 | * mutual recursion. |
| 993 | */ |
| 994 | void __pagevec_release(struct pagevec *pvec) |
| 995 | { |
| 996 | if (!pvec->percpu_pvec_drained) { |
| 997 | lru_add_drain(); |
| 998 | pvec->percpu_pvec_drained = true; |
| 999 | } |
| 1000 | release_pages(pvec->pages, pagevec_count(pvec)); |
| 1001 | pagevec_reinit(pvec); |
| 1002 | } |
| 1003 | EXPORT_SYMBOL(__pagevec_release); |
| 1004 | |
| 1005 | static void __pagevec_lru_add_fn(struct folio *folio, struct lruvec *lruvec) |
| 1006 | { |
| 1007 | int was_unevictable = folio_test_clear_unevictable(folio); |
| 1008 | long nr_pages = folio_nr_pages(folio); |
| 1009 | |
| 1010 | VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); |
| 1011 | |
| 1012 | /* |
| 1013 | * A folio becomes evictable in two ways: |
| 1014 | * 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()]. |
| 1015 | * 2) Before acquiring LRU lock to put the folio on the correct LRU |
| 1016 | * and then |
| 1017 | * a) do PageLRU check with lock [check_move_unevictable_pages] |
| 1018 | * b) do PageLRU check before lock [clear_page_mlock] |
| 1019 | * |
| 1020 | * (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need |
| 1021 | * following strict ordering: |
| 1022 | * |
| 1023 | * #0: __pagevec_lru_add_fn #1: clear_page_mlock |
| 1024 | * |
| 1025 | * folio_set_lru() folio_test_clear_mlocked() |
| 1026 | * smp_mb() // explicit ordering // above provides strict |
| 1027 | * // ordering |
| 1028 | * folio_test_mlocked() folio_test_lru() |
| 1029 | * |
| 1030 | * |
| 1031 | * if '#1' does not observe setting of PG_lru by '#0' and |
| 1032 | * fails isolation, the explicit barrier will make sure that |
| 1033 | * folio_evictable check will put the folio on the correct |
| 1034 | * LRU. Without smp_mb(), folio_set_lru() can be reordered |
| 1035 | * after folio_test_mlocked() check and can make '#1' fail the |
| 1036 | * isolation of the folio whose mlocked bit is cleared (#0 is |
| 1037 | * also looking at the same folio) and the evictable folio will |
| 1038 | * be stranded on an unevictable LRU. |
| 1039 | */ |
| 1040 | folio_set_lru(folio); |
| 1041 | smp_mb__after_atomic(); |
| 1042 | |
| 1043 | if (folio_evictable(folio)) { |
| 1044 | if (was_unevictable) |
| 1045 | __count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages); |
| 1046 | } else { |
| 1047 | folio_clear_active(folio); |
| 1048 | folio_set_unevictable(folio); |
| 1049 | if (!was_unevictable) |
| 1050 | __count_vm_events(UNEVICTABLE_PGCULLED, nr_pages); |
| 1051 | } |
| 1052 | |
| 1053 | lruvec_add_folio(lruvec, folio); |
| 1054 | trace_mm_lru_insertion(folio); |
| 1055 | } |
| 1056 | |
| 1057 | /* |
| 1058 | * Add the passed pages to the LRU, then drop the caller's refcount |
| 1059 | * on them. Reinitialises the caller's pagevec. |
| 1060 | */ |
| 1061 | void __pagevec_lru_add(struct pagevec *pvec) |
| 1062 | { |
| 1063 | int i; |
| 1064 | struct lruvec *lruvec = NULL; |
| 1065 | unsigned long flags = 0; |
| 1066 | |
| 1067 | for (i = 0; i < pagevec_count(pvec); i++) { |
| 1068 | struct folio *folio = page_folio(pvec->pages[i]); |
| 1069 | |
| 1070 | lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags); |
| 1071 | __pagevec_lru_add_fn(folio, lruvec); |
| 1072 | } |
| 1073 | if (lruvec) |
| 1074 | unlock_page_lruvec_irqrestore(lruvec, flags); |
| 1075 | release_pages(pvec->pages, pvec->nr); |
| 1076 | pagevec_reinit(pvec); |
| 1077 | } |
| 1078 | |
| 1079 | /** |
| 1080 | * folio_batch_remove_exceptionals() - Prune non-folios from a batch. |
| 1081 | * @fbatch: The batch to prune |
| 1082 | * |
| 1083 | * find_get_entries() fills a batch with both folios and shadow/swap/DAX |
| 1084 | * entries. This function prunes all the non-folio entries from @fbatch |
| 1085 | * without leaving holes, so that it can be passed on to folio-only batch |
| 1086 | * operations. |
| 1087 | */ |
| 1088 | void folio_batch_remove_exceptionals(struct folio_batch *fbatch) |
| 1089 | { |
| 1090 | unsigned int i, j; |
| 1091 | |
| 1092 | for (i = 0, j = 0; i < folio_batch_count(fbatch); i++) { |
| 1093 | struct folio *folio = fbatch->folios[i]; |
| 1094 | if (!xa_is_value(folio)) |
| 1095 | fbatch->folios[j++] = folio; |
| 1096 | } |
| 1097 | fbatch->nr = j; |
| 1098 | } |
| 1099 | |
| 1100 | /** |
| 1101 | * pagevec_lookup_range - gang pagecache lookup |
| 1102 | * @pvec: Where the resulting pages are placed |
| 1103 | * @mapping: The address_space to search |
| 1104 | * @start: The starting page index |
| 1105 | * @end: The final page index |
| 1106 | * |
| 1107 | * pagevec_lookup_range() will search for & return a group of up to PAGEVEC_SIZE |
| 1108 | * pages in the mapping starting from index @start and upto index @end |
| 1109 | * (inclusive). The pages are placed in @pvec. pagevec_lookup() takes a |
| 1110 | * reference against the pages in @pvec. |
| 1111 | * |
| 1112 | * The search returns a group of mapping-contiguous pages with ascending |
| 1113 | * indexes. There may be holes in the indices due to not-present pages. We |
| 1114 | * also update @start to index the next page for the traversal. |
| 1115 | * |
| 1116 | * pagevec_lookup_range() returns the number of pages which were found. If this |
| 1117 | * number is smaller than PAGEVEC_SIZE, the end of specified range has been |
| 1118 | * reached. |
| 1119 | */ |
| 1120 | unsigned pagevec_lookup_range(struct pagevec *pvec, |
| 1121 | struct address_space *mapping, pgoff_t *start, pgoff_t end) |
| 1122 | { |
| 1123 | pvec->nr = find_get_pages_range(mapping, start, end, PAGEVEC_SIZE, |
| 1124 | pvec->pages); |
| 1125 | return pagevec_count(pvec); |
| 1126 | } |
| 1127 | EXPORT_SYMBOL(pagevec_lookup_range); |
| 1128 | |
| 1129 | unsigned pagevec_lookup_range_tag(struct pagevec *pvec, |
| 1130 | struct address_space *mapping, pgoff_t *index, pgoff_t end, |
| 1131 | xa_mark_t tag) |
| 1132 | { |
| 1133 | pvec->nr = find_get_pages_range_tag(mapping, index, end, tag, |
| 1134 | PAGEVEC_SIZE, pvec->pages); |
| 1135 | return pagevec_count(pvec); |
| 1136 | } |
| 1137 | EXPORT_SYMBOL(pagevec_lookup_range_tag); |
| 1138 | |
| 1139 | /* |
| 1140 | * Perform any setup for the swap system |
| 1141 | */ |
| 1142 | void __init swap_setup(void) |
| 1143 | { |
| 1144 | unsigned long megs = totalram_pages() >> (20 - PAGE_SHIFT); |
| 1145 | |
| 1146 | /* Use a smaller cluster for small-memory machines */ |
| 1147 | if (megs < 16) |
| 1148 | page_cluster = 2; |
| 1149 | else |
| 1150 | page_cluster = 3; |
| 1151 | /* |
| 1152 | * Right now other parts of the system means that we |
| 1153 | * _really_ don't want to cluster much more |
| 1154 | */ |
| 1155 | } |
| 1156 | |
| 1157 | #ifdef CONFIG_DEV_PAGEMAP_OPS |
| 1158 | void put_devmap_managed_page(struct page *page) |
| 1159 | { |
| 1160 | int count; |
| 1161 | |
| 1162 | if (WARN_ON_ONCE(!page_is_devmap_managed(page))) |
| 1163 | return; |
| 1164 | |
| 1165 | count = page_ref_dec_return(page); |
| 1166 | |
| 1167 | /* |
| 1168 | * devmap page refcounts are 1-based, rather than 0-based: if |
| 1169 | * refcount is 1, then the page is free and the refcount is |
| 1170 | * stable because nobody holds a reference on the page. |
| 1171 | */ |
| 1172 | if (count == 1) |
| 1173 | free_devmap_managed_page(page); |
| 1174 | else if (!count) |
| 1175 | __put_page(page); |
| 1176 | } |
| 1177 | EXPORT_SYMBOL(put_devmap_managed_page); |
| 1178 | #endif |