| 1 | /* |
| 2 | * Memory Migration functionality - linux/mm/migrate.c |
| 3 | * |
| 4 | * Copyright (C) 2006 Silicon Graphics, Inc., Christoph Lameter |
| 5 | * |
| 6 | * Page migration was first developed in the context of the memory hotplug |
| 7 | * project. The main authors of the migration code are: |
| 8 | * |
| 9 | * IWAMOTO Toshihiro <iwamoto@valinux.co.jp> |
| 10 | * Hirokazu Takahashi <taka@valinux.co.jp> |
| 11 | * Dave Hansen <haveblue@us.ibm.com> |
| 12 | * Christoph Lameter |
| 13 | */ |
| 14 | |
| 15 | #include <linux/migrate.h> |
| 16 | #include <linux/export.h> |
| 17 | #include <linux/swap.h> |
| 18 | #include <linux/swapops.h> |
| 19 | #include <linux/pagemap.h> |
| 20 | #include <linux/buffer_head.h> |
| 21 | #include <linux/mm_inline.h> |
| 22 | #include <linux/nsproxy.h> |
| 23 | #include <linux/pagevec.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/hugetlb.h> |
| 37 | #include <linux/hugetlb_cgroup.h> |
| 38 | #include <linux/gfp.h> |
| 39 | #include <linux/balloon_compaction.h> |
| 40 | #include <linux/mmu_notifier.h> |
| 41 | #include <linux/page_idle.h> |
| 42 | #include <linux/page_owner.h> |
| 43 | |
| 44 | #include <asm/tlbflush.h> |
| 45 | |
| 46 | #define CREATE_TRACE_POINTS |
| 47 | #include <trace/events/migrate.h> |
| 48 | |
| 49 | #include "internal.h" |
| 50 | |
| 51 | /* |
| 52 | * migrate_prep() needs to be called before we start compiling a list of pages |
| 53 | * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is |
| 54 | * undesirable, use migrate_prep_local() |
| 55 | */ |
| 56 | int migrate_prep(void) |
| 57 | { |
| 58 | /* |
| 59 | * Clear the LRU lists so pages can be isolated. |
| 60 | * Note that pages may be moved off the LRU after we have |
| 61 | * drained them. Those pages will fail to migrate like other |
| 62 | * pages that may be busy. |
| 63 | */ |
| 64 | lru_add_drain_all(); |
| 65 | |
| 66 | return 0; |
| 67 | } |
| 68 | |
| 69 | /* Do the necessary work of migrate_prep but not if it involves other CPUs */ |
| 70 | int migrate_prep_local(void) |
| 71 | { |
| 72 | lru_add_drain(); |
| 73 | |
| 74 | return 0; |
| 75 | } |
| 76 | |
| 77 | bool isolate_movable_page(struct page *page, isolate_mode_t mode) |
| 78 | { |
| 79 | struct address_space *mapping; |
| 80 | |
| 81 | /* |
| 82 | * Avoid burning cycles with pages that are yet under __free_pages(), |
| 83 | * or just got freed under us. |
| 84 | * |
| 85 | * In case we 'win' a race for a movable page being freed under us and |
| 86 | * raise its refcount preventing __free_pages() from doing its job |
| 87 | * the put_page() at the end of this block will take care of |
| 88 | * release this page, thus avoiding a nasty leakage. |
| 89 | */ |
| 90 | if (unlikely(!get_page_unless_zero(page))) |
| 91 | goto out; |
| 92 | |
| 93 | /* |
| 94 | * Check PageMovable before holding a PG_lock because page's owner |
| 95 | * assumes anybody doesn't touch PG_lock of newly allocated page |
| 96 | * so unconditionally grapping the lock ruins page's owner side. |
| 97 | */ |
| 98 | if (unlikely(!__PageMovable(page))) |
| 99 | goto out_putpage; |
| 100 | /* |
| 101 | * As movable pages are not isolated from LRU lists, concurrent |
| 102 | * compaction threads can race against page migration functions |
| 103 | * as well as race against the releasing a page. |
| 104 | * |
| 105 | * In order to avoid having an already isolated movable page |
| 106 | * being (wrongly) re-isolated while it is under migration, |
| 107 | * or to avoid attempting to isolate pages being released, |
| 108 | * lets be sure we have the page lock |
| 109 | * before proceeding with the movable page isolation steps. |
| 110 | */ |
| 111 | if (unlikely(!trylock_page(page))) |
| 112 | goto out_putpage; |
| 113 | |
| 114 | if (!PageMovable(page) || PageIsolated(page)) |
| 115 | goto out_no_isolated; |
| 116 | |
| 117 | mapping = page_mapping(page); |
| 118 | VM_BUG_ON_PAGE(!mapping, page); |
| 119 | |
| 120 | if (!mapping->a_ops->isolate_page(page, mode)) |
| 121 | goto out_no_isolated; |
| 122 | |
| 123 | /* Driver shouldn't use PG_isolated bit of page->flags */ |
| 124 | WARN_ON_ONCE(PageIsolated(page)); |
| 125 | __SetPageIsolated(page); |
| 126 | unlock_page(page); |
| 127 | |
| 128 | return true; |
| 129 | |
| 130 | out_no_isolated: |
| 131 | unlock_page(page); |
| 132 | out_putpage: |
| 133 | put_page(page); |
| 134 | out: |
| 135 | return false; |
| 136 | } |
| 137 | |
| 138 | /* It should be called on page which is PG_movable */ |
| 139 | void putback_movable_page(struct page *page) |
| 140 | { |
| 141 | struct address_space *mapping; |
| 142 | |
| 143 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
| 144 | VM_BUG_ON_PAGE(!PageMovable(page), page); |
| 145 | VM_BUG_ON_PAGE(!PageIsolated(page), page); |
| 146 | |
| 147 | mapping = page_mapping(page); |
| 148 | mapping->a_ops->putback_page(page); |
| 149 | __ClearPageIsolated(page); |
| 150 | } |
| 151 | |
| 152 | /* |
| 153 | * Put previously isolated pages back onto the appropriate lists |
| 154 | * from where they were once taken off for compaction/migration. |
| 155 | * |
| 156 | * This function shall be used whenever the isolated pageset has been |
| 157 | * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range() |
| 158 | * and isolate_huge_page(). |
| 159 | */ |
| 160 | void putback_movable_pages(struct list_head *l) |
| 161 | { |
| 162 | struct page *page; |
| 163 | struct page *page2; |
| 164 | |
| 165 | list_for_each_entry_safe(page, page2, l, lru) { |
| 166 | if (unlikely(PageHuge(page))) { |
| 167 | putback_active_hugepage(page); |
| 168 | continue; |
| 169 | } |
| 170 | list_del(&page->lru); |
| 171 | /* |
| 172 | * We isolated non-lru movable page so here we can use |
| 173 | * __PageMovable because LRU page's mapping cannot have |
| 174 | * PAGE_MAPPING_MOVABLE. |
| 175 | */ |
| 176 | if (unlikely(__PageMovable(page))) { |
| 177 | VM_BUG_ON_PAGE(!PageIsolated(page), page); |
| 178 | lock_page(page); |
| 179 | if (PageMovable(page)) |
| 180 | putback_movable_page(page); |
| 181 | else |
| 182 | __ClearPageIsolated(page); |
| 183 | unlock_page(page); |
| 184 | put_page(page); |
| 185 | } else { |
| 186 | putback_lru_page(page); |
| 187 | dec_node_page_state(page, NR_ISOLATED_ANON + |
| 188 | page_is_file_cache(page)); |
| 189 | } |
| 190 | } |
| 191 | } |
| 192 | |
| 193 | /* |
| 194 | * Restore a potential migration pte to a working pte entry |
| 195 | */ |
| 196 | static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, |
| 197 | unsigned long addr, void *old) |
| 198 | { |
| 199 | struct mm_struct *mm = vma->vm_mm; |
| 200 | swp_entry_t entry; |
| 201 | pmd_t *pmd; |
| 202 | pte_t *ptep, pte; |
| 203 | spinlock_t *ptl; |
| 204 | |
| 205 | if (unlikely(PageHuge(new))) { |
| 206 | ptep = huge_pte_offset(mm, addr); |
| 207 | if (!ptep) |
| 208 | goto out; |
| 209 | ptl = huge_pte_lockptr(hstate_vma(vma), mm, ptep); |
| 210 | } else { |
| 211 | pmd = mm_find_pmd(mm, addr); |
| 212 | if (!pmd) |
| 213 | goto out; |
| 214 | |
| 215 | ptep = pte_offset_map(pmd, addr); |
| 216 | |
| 217 | /* |
| 218 | * Peek to check is_swap_pte() before taking ptlock? No, we |
| 219 | * can race mremap's move_ptes(), which skips anon_vma lock. |
| 220 | */ |
| 221 | |
| 222 | ptl = pte_lockptr(mm, pmd); |
| 223 | } |
| 224 | |
| 225 | spin_lock(ptl); |
| 226 | pte = *ptep; |
| 227 | if (!is_swap_pte(pte)) |
| 228 | goto unlock; |
| 229 | |
| 230 | entry = pte_to_swp_entry(pte); |
| 231 | |
| 232 | if (!is_migration_entry(entry) || |
| 233 | migration_entry_to_page(entry) != old) |
| 234 | goto unlock; |
| 235 | |
| 236 | get_page(new); |
| 237 | pte = pte_mkold(mk_pte(new, READ_ONCE(vma->vm_page_prot))); |
| 238 | if (pte_swp_soft_dirty(*ptep)) |
| 239 | pte = pte_mksoft_dirty(pte); |
| 240 | |
| 241 | /* Recheck VMA as permissions can change since migration started */ |
| 242 | if (is_write_migration_entry(entry)) |
| 243 | pte = maybe_mkwrite(pte, vma); |
| 244 | |
| 245 | #ifdef CONFIG_HUGETLB_PAGE |
| 246 | if (PageHuge(new)) { |
| 247 | pte = pte_mkhuge(pte); |
| 248 | pte = arch_make_huge_pte(pte, vma, new, 0); |
| 249 | } |
| 250 | #endif |
| 251 | flush_dcache_page(new); |
| 252 | set_pte_at(mm, addr, ptep, pte); |
| 253 | |
| 254 | if (PageHuge(new)) { |
| 255 | if (PageAnon(new)) |
| 256 | hugepage_add_anon_rmap(new, vma, addr); |
| 257 | else |
| 258 | page_dup_rmap(new, true); |
| 259 | } else if (PageAnon(new)) |
| 260 | page_add_anon_rmap(new, vma, addr, false); |
| 261 | else |
| 262 | page_add_file_rmap(new, false); |
| 263 | |
| 264 | if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new)) |
| 265 | mlock_vma_page(new); |
| 266 | |
| 267 | /* No need to invalidate - it was non-present before */ |
| 268 | update_mmu_cache(vma, addr, ptep); |
| 269 | unlock: |
| 270 | pte_unmap_unlock(ptep, ptl); |
| 271 | out: |
| 272 | return SWAP_AGAIN; |
| 273 | } |
| 274 | |
| 275 | /* |
| 276 | * Get rid of all migration entries and replace them by |
| 277 | * references to the indicated page. |
| 278 | */ |
| 279 | void remove_migration_ptes(struct page *old, struct page *new, bool locked) |
| 280 | { |
| 281 | struct rmap_walk_control rwc = { |
| 282 | .rmap_one = remove_migration_pte, |
| 283 | .arg = old, |
| 284 | }; |
| 285 | |
| 286 | if (locked) |
| 287 | rmap_walk_locked(new, &rwc); |
| 288 | else |
| 289 | rmap_walk(new, &rwc); |
| 290 | } |
| 291 | |
| 292 | /* |
| 293 | * Something used the pte of a page under migration. We need to |
| 294 | * get to the page and wait until migration is finished. |
| 295 | * When we return from this function the fault will be retried. |
| 296 | */ |
| 297 | void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, |
| 298 | spinlock_t *ptl) |
| 299 | { |
| 300 | pte_t pte; |
| 301 | swp_entry_t entry; |
| 302 | struct page *page; |
| 303 | |
| 304 | spin_lock(ptl); |
| 305 | pte = *ptep; |
| 306 | if (!is_swap_pte(pte)) |
| 307 | goto out; |
| 308 | |
| 309 | entry = pte_to_swp_entry(pte); |
| 310 | if (!is_migration_entry(entry)) |
| 311 | goto out; |
| 312 | |
| 313 | page = migration_entry_to_page(entry); |
| 314 | |
| 315 | /* |
| 316 | * Once radix-tree replacement of page migration started, page_count |
| 317 | * *must* be zero. And, we don't want to call wait_on_page_locked() |
| 318 | * against a page without get_page(). |
| 319 | * So, we use get_page_unless_zero(), here. Even failed, page fault |
| 320 | * will occur again. |
| 321 | */ |
| 322 | if (!get_page_unless_zero(page)) |
| 323 | goto out; |
| 324 | pte_unmap_unlock(ptep, ptl); |
| 325 | wait_on_page_locked(page); |
| 326 | put_page(page); |
| 327 | return; |
| 328 | out: |
| 329 | pte_unmap_unlock(ptep, ptl); |
| 330 | } |
| 331 | |
| 332 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, |
| 333 | unsigned long address) |
| 334 | { |
| 335 | spinlock_t *ptl = pte_lockptr(mm, pmd); |
| 336 | pte_t *ptep = pte_offset_map(pmd, address); |
| 337 | __migration_entry_wait(mm, ptep, ptl); |
| 338 | } |
| 339 | |
| 340 | void migration_entry_wait_huge(struct vm_area_struct *vma, |
| 341 | struct mm_struct *mm, pte_t *pte) |
| 342 | { |
| 343 | spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte); |
| 344 | __migration_entry_wait(mm, pte, ptl); |
| 345 | } |
| 346 | |
| 347 | #ifdef CONFIG_BLOCK |
| 348 | /* Returns true if all buffers are successfully locked */ |
| 349 | static bool buffer_migrate_lock_buffers(struct buffer_head *head, |
| 350 | enum migrate_mode mode) |
| 351 | { |
| 352 | struct buffer_head *bh = head; |
| 353 | |
| 354 | /* Simple case, sync compaction */ |
| 355 | if (mode != MIGRATE_ASYNC) { |
| 356 | do { |
| 357 | get_bh(bh); |
| 358 | lock_buffer(bh); |
| 359 | bh = bh->b_this_page; |
| 360 | |
| 361 | } while (bh != head); |
| 362 | |
| 363 | return true; |
| 364 | } |
| 365 | |
| 366 | /* async case, we cannot block on lock_buffer so use trylock_buffer */ |
| 367 | do { |
| 368 | get_bh(bh); |
| 369 | if (!trylock_buffer(bh)) { |
| 370 | /* |
| 371 | * We failed to lock the buffer and cannot stall in |
| 372 | * async migration. Release the taken locks |
| 373 | */ |
| 374 | struct buffer_head *failed_bh = bh; |
| 375 | put_bh(failed_bh); |
| 376 | bh = head; |
| 377 | while (bh != failed_bh) { |
| 378 | unlock_buffer(bh); |
| 379 | put_bh(bh); |
| 380 | bh = bh->b_this_page; |
| 381 | } |
| 382 | return false; |
| 383 | } |
| 384 | |
| 385 | bh = bh->b_this_page; |
| 386 | } while (bh != head); |
| 387 | return true; |
| 388 | } |
| 389 | #else |
| 390 | static inline bool buffer_migrate_lock_buffers(struct buffer_head *head, |
| 391 | enum migrate_mode mode) |
| 392 | { |
| 393 | return true; |
| 394 | } |
| 395 | #endif /* CONFIG_BLOCK */ |
| 396 | |
| 397 | /* |
| 398 | * Replace the page in the mapping. |
| 399 | * |
| 400 | * The number of remaining references must be: |
| 401 | * 1 for anonymous pages without a mapping |
| 402 | * 2 for pages with a mapping |
| 403 | * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. |
| 404 | */ |
| 405 | int migrate_page_move_mapping(struct address_space *mapping, |
| 406 | struct page *newpage, struct page *page, |
| 407 | struct buffer_head *head, enum migrate_mode mode, |
| 408 | int extra_count) |
| 409 | { |
| 410 | struct zone *oldzone, *newzone; |
| 411 | int dirty; |
| 412 | int expected_count = 1 + extra_count; |
| 413 | void **pslot; |
| 414 | |
| 415 | if (!mapping) { |
| 416 | /* Anonymous page without mapping */ |
| 417 | if (page_count(page) != expected_count) |
| 418 | return -EAGAIN; |
| 419 | |
| 420 | /* No turning back from here */ |
| 421 | newpage->index = page->index; |
| 422 | newpage->mapping = page->mapping; |
| 423 | if (PageSwapBacked(page)) |
| 424 | __SetPageSwapBacked(newpage); |
| 425 | |
| 426 | return MIGRATEPAGE_SUCCESS; |
| 427 | } |
| 428 | |
| 429 | oldzone = page_zone(page); |
| 430 | newzone = page_zone(newpage); |
| 431 | |
| 432 | spin_lock_irq(&mapping->tree_lock); |
| 433 | |
| 434 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
| 435 | page_index(page)); |
| 436 | |
| 437 | expected_count += 1 + page_has_private(page); |
| 438 | if (page_count(page) != expected_count || |
| 439 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { |
| 440 | spin_unlock_irq(&mapping->tree_lock); |
| 441 | return -EAGAIN; |
| 442 | } |
| 443 | |
| 444 | if (!page_ref_freeze(page, expected_count)) { |
| 445 | spin_unlock_irq(&mapping->tree_lock); |
| 446 | return -EAGAIN; |
| 447 | } |
| 448 | |
| 449 | /* |
| 450 | * In the async migration case of moving a page with buffers, lock the |
| 451 | * buffers using trylock before the mapping is moved. If the mapping |
| 452 | * was moved, we later failed to lock the buffers and could not move |
| 453 | * the mapping back due to an elevated page count, we would have to |
| 454 | * block waiting on other references to be dropped. |
| 455 | */ |
| 456 | if (mode == MIGRATE_ASYNC && head && |
| 457 | !buffer_migrate_lock_buffers(head, mode)) { |
| 458 | page_ref_unfreeze(page, expected_count); |
| 459 | spin_unlock_irq(&mapping->tree_lock); |
| 460 | return -EAGAIN; |
| 461 | } |
| 462 | |
| 463 | /* |
| 464 | * Now we know that no one else is looking at the page: |
| 465 | * no turning back from here. |
| 466 | */ |
| 467 | newpage->index = page->index; |
| 468 | newpage->mapping = page->mapping; |
| 469 | get_page(newpage); /* add cache reference */ |
| 470 | if (PageSwapBacked(page)) { |
| 471 | __SetPageSwapBacked(newpage); |
| 472 | if (PageSwapCache(page)) { |
| 473 | SetPageSwapCache(newpage); |
| 474 | set_page_private(newpage, page_private(page)); |
| 475 | } |
| 476 | } else { |
| 477 | VM_BUG_ON_PAGE(PageSwapCache(page), page); |
| 478 | } |
| 479 | |
| 480 | /* Move dirty while page refs frozen and newpage not yet exposed */ |
| 481 | dirty = PageDirty(page); |
| 482 | if (dirty) { |
| 483 | ClearPageDirty(page); |
| 484 | SetPageDirty(newpage); |
| 485 | } |
| 486 | |
| 487 | radix_tree_replace_slot(&mapping->page_tree, pslot, newpage); |
| 488 | |
| 489 | /* |
| 490 | * Drop cache reference from old page by unfreezing |
| 491 | * to one less reference. |
| 492 | * We know this isn't the last reference. |
| 493 | */ |
| 494 | page_ref_unfreeze(page, expected_count - 1); |
| 495 | |
| 496 | spin_unlock(&mapping->tree_lock); |
| 497 | /* Leave irq disabled to prevent preemption while updating stats */ |
| 498 | |
| 499 | /* |
| 500 | * If moved to a different zone then also account |
| 501 | * the page for that zone. Other VM counters will be |
| 502 | * taken care of when we establish references to the |
| 503 | * new page and drop references to the old page. |
| 504 | * |
| 505 | * Note that anonymous pages are accounted for |
| 506 | * via NR_FILE_PAGES and NR_ANON_MAPPED if they |
| 507 | * are mapped to swap space. |
| 508 | */ |
| 509 | if (newzone != oldzone) { |
| 510 | __dec_node_state(oldzone->zone_pgdat, NR_FILE_PAGES); |
| 511 | __inc_node_state(newzone->zone_pgdat, NR_FILE_PAGES); |
| 512 | if (PageSwapBacked(page) && !PageSwapCache(page)) { |
| 513 | __dec_node_state(oldzone->zone_pgdat, NR_SHMEM); |
| 514 | __inc_node_state(newzone->zone_pgdat, NR_SHMEM); |
| 515 | } |
| 516 | if (dirty && mapping_cap_account_dirty(mapping)) { |
| 517 | __dec_node_state(oldzone->zone_pgdat, NR_FILE_DIRTY); |
| 518 | __dec_zone_state(oldzone, NR_ZONE_WRITE_PENDING); |
| 519 | __inc_node_state(newzone->zone_pgdat, NR_FILE_DIRTY); |
| 520 | __inc_zone_state(newzone, NR_ZONE_WRITE_PENDING); |
| 521 | } |
| 522 | } |
| 523 | local_irq_enable(); |
| 524 | |
| 525 | return MIGRATEPAGE_SUCCESS; |
| 526 | } |
| 527 | EXPORT_SYMBOL(migrate_page_move_mapping); |
| 528 | |
| 529 | /* |
| 530 | * The expected number of remaining references is the same as that |
| 531 | * of migrate_page_move_mapping(). |
| 532 | */ |
| 533 | int migrate_huge_page_move_mapping(struct address_space *mapping, |
| 534 | struct page *newpage, struct page *page) |
| 535 | { |
| 536 | int expected_count; |
| 537 | void **pslot; |
| 538 | |
| 539 | spin_lock_irq(&mapping->tree_lock); |
| 540 | |
| 541 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
| 542 | page_index(page)); |
| 543 | |
| 544 | expected_count = 2 + page_has_private(page); |
| 545 | if (page_count(page) != expected_count || |
| 546 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { |
| 547 | spin_unlock_irq(&mapping->tree_lock); |
| 548 | return -EAGAIN; |
| 549 | } |
| 550 | |
| 551 | if (!page_ref_freeze(page, expected_count)) { |
| 552 | spin_unlock_irq(&mapping->tree_lock); |
| 553 | return -EAGAIN; |
| 554 | } |
| 555 | |
| 556 | newpage->index = page->index; |
| 557 | newpage->mapping = page->mapping; |
| 558 | |
| 559 | get_page(newpage); |
| 560 | |
| 561 | radix_tree_replace_slot(&mapping->page_tree, pslot, newpage); |
| 562 | |
| 563 | page_ref_unfreeze(page, expected_count - 1); |
| 564 | |
| 565 | spin_unlock_irq(&mapping->tree_lock); |
| 566 | |
| 567 | return MIGRATEPAGE_SUCCESS; |
| 568 | } |
| 569 | |
| 570 | /* |
| 571 | * Gigantic pages are so large that we do not guarantee that page++ pointer |
| 572 | * arithmetic will work across the entire page. We need something more |
| 573 | * specialized. |
| 574 | */ |
| 575 | static void __copy_gigantic_page(struct page *dst, struct page *src, |
| 576 | int nr_pages) |
| 577 | { |
| 578 | int i; |
| 579 | struct page *dst_base = dst; |
| 580 | struct page *src_base = src; |
| 581 | |
| 582 | for (i = 0; i < nr_pages; ) { |
| 583 | cond_resched(); |
| 584 | copy_highpage(dst, src); |
| 585 | |
| 586 | i++; |
| 587 | dst = mem_map_next(dst, dst_base, i); |
| 588 | src = mem_map_next(src, src_base, i); |
| 589 | } |
| 590 | } |
| 591 | |
| 592 | static void copy_huge_page(struct page *dst, struct page *src) |
| 593 | { |
| 594 | int i; |
| 595 | int nr_pages; |
| 596 | |
| 597 | if (PageHuge(src)) { |
| 598 | /* hugetlbfs page */ |
| 599 | struct hstate *h = page_hstate(src); |
| 600 | nr_pages = pages_per_huge_page(h); |
| 601 | |
| 602 | if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) { |
| 603 | __copy_gigantic_page(dst, src, nr_pages); |
| 604 | return; |
| 605 | } |
| 606 | } else { |
| 607 | /* thp page */ |
| 608 | BUG_ON(!PageTransHuge(src)); |
| 609 | nr_pages = hpage_nr_pages(src); |
| 610 | } |
| 611 | |
| 612 | for (i = 0; i < nr_pages; i++) { |
| 613 | cond_resched(); |
| 614 | copy_highpage(dst + i, src + i); |
| 615 | } |
| 616 | } |
| 617 | |
| 618 | /* |
| 619 | * Copy the page to its new location |
| 620 | */ |
| 621 | void migrate_page_copy(struct page *newpage, struct page *page) |
| 622 | { |
| 623 | int cpupid; |
| 624 | |
| 625 | if (PageHuge(page) || PageTransHuge(page)) |
| 626 | copy_huge_page(newpage, page); |
| 627 | else |
| 628 | copy_highpage(newpage, page); |
| 629 | |
| 630 | if (PageError(page)) |
| 631 | SetPageError(newpage); |
| 632 | if (PageReferenced(page)) |
| 633 | SetPageReferenced(newpage); |
| 634 | if (PageUptodate(page)) |
| 635 | SetPageUptodate(newpage); |
| 636 | if (TestClearPageActive(page)) { |
| 637 | VM_BUG_ON_PAGE(PageUnevictable(page), page); |
| 638 | SetPageActive(newpage); |
| 639 | } else if (TestClearPageUnevictable(page)) |
| 640 | SetPageUnevictable(newpage); |
| 641 | if (PageChecked(page)) |
| 642 | SetPageChecked(newpage); |
| 643 | if (PageMappedToDisk(page)) |
| 644 | SetPageMappedToDisk(newpage); |
| 645 | |
| 646 | /* Move dirty on pages not done by migrate_page_move_mapping() */ |
| 647 | if (PageDirty(page)) |
| 648 | SetPageDirty(newpage); |
| 649 | |
| 650 | if (page_is_young(page)) |
| 651 | set_page_young(newpage); |
| 652 | if (page_is_idle(page)) |
| 653 | set_page_idle(newpage); |
| 654 | |
| 655 | /* |
| 656 | * Copy NUMA information to the new page, to prevent over-eager |
| 657 | * future migrations of this same page. |
| 658 | */ |
| 659 | cpupid = page_cpupid_xchg_last(page, -1); |
| 660 | page_cpupid_xchg_last(newpage, cpupid); |
| 661 | |
| 662 | ksm_migrate_page(newpage, page); |
| 663 | /* |
| 664 | * Please do not reorder this without considering how mm/ksm.c's |
| 665 | * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache(). |
| 666 | */ |
| 667 | if (PageSwapCache(page)) |
| 668 | ClearPageSwapCache(page); |
| 669 | ClearPagePrivate(page); |
| 670 | set_page_private(page, 0); |
| 671 | |
| 672 | /* |
| 673 | * If any waiters have accumulated on the new page then |
| 674 | * wake them up. |
| 675 | */ |
| 676 | if (PageWriteback(newpage)) |
| 677 | end_page_writeback(newpage); |
| 678 | |
| 679 | copy_page_owner(page, newpage); |
| 680 | |
| 681 | mem_cgroup_migrate(page, newpage); |
| 682 | } |
| 683 | EXPORT_SYMBOL(migrate_page_copy); |
| 684 | |
| 685 | /************************************************************ |
| 686 | * Migration functions |
| 687 | ***********************************************************/ |
| 688 | |
| 689 | /* |
| 690 | * Common logic to directly migrate a single LRU page suitable for |
| 691 | * pages that do not use PagePrivate/PagePrivate2. |
| 692 | * |
| 693 | * Pages are locked upon entry and exit. |
| 694 | */ |
| 695 | int migrate_page(struct address_space *mapping, |
| 696 | struct page *newpage, struct page *page, |
| 697 | enum migrate_mode mode) |
| 698 | { |
| 699 | int rc; |
| 700 | |
| 701 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ |
| 702 | |
| 703 | rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0); |
| 704 | |
| 705 | if (rc != MIGRATEPAGE_SUCCESS) |
| 706 | return rc; |
| 707 | |
| 708 | migrate_page_copy(newpage, page); |
| 709 | return MIGRATEPAGE_SUCCESS; |
| 710 | } |
| 711 | EXPORT_SYMBOL(migrate_page); |
| 712 | |
| 713 | #ifdef CONFIG_BLOCK |
| 714 | /* |
| 715 | * Migration function for pages with buffers. This function can only be used |
| 716 | * if the underlying filesystem guarantees that no other references to "page" |
| 717 | * exist. |
| 718 | */ |
| 719 | int buffer_migrate_page(struct address_space *mapping, |
| 720 | struct page *newpage, struct page *page, enum migrate_mode mode) |
| 721 | { |
| 722 | struct buffer_head *bh, *head; |
| 723 | int rc; |
| 724 | |
| 725 | if (!page_has_buffers(page)) |
| 726 | return migrate_page(mapping, newpage, page, mode); |
| 727 | |
| 728 | head = page_buffers(page); |
| 729 | |
| 730 | rc = migrate_page_move_mapping(mapping, newpage, page, head, mode, 0); |
| 731 | |
| 732 | if (rc != MIGRATEPAGE_SUCCESS) |
| 733 | return rc; |
| 734 | |
| 735 | /* |
| 736 | * In the async case, migrate_page_move_mapping locked the buffers |
| 737 | * with an IRQ-safe spinlock held. In the sync case, the buffers |
| 738 | * need to be locked now |
| 739 | */ |
| 740 | if (mode != MIGRATE_ASYNC) |
| 741 | BUG_ON(!buffer_migrate_lock_buffers(head, mode)); |
| 742 | |
| 743 | ClearPagePrivate(page); |
| 744 | set_page_private(newpage, page_private(page)); |
| 745 | set_page_private(page, 0); |
| 746 | put_page(page); |
| 747 | get_page(newpage); |
| 748 | |
| 749 | bh = head; |
| 750 | do { |
| 751 | set_bh_page(bh, newpage, bh_offset(bh)); |
| 752 | bh = bh->b_this_page; |
| 753 | |
| 754 | } while (bh != head); |
| 755 | |
| 756 | SetPagePrivate(newpage); |
| 757 | |
| 758 | migrate_page_copy(newpage, page); |
| 759 | |
| 760 | bh = head; |
| 761 | do { |
| 762 | unlock_buffer(bh); |
| 763 | put_bh(bh); |
| 764 | bh = bh->b_this_page; |
| 765 | |
| 766 | } while (bh != head); |
| 767 | |
| 768 | return MIGRATEPAGE_SUCCESS; |
| 769 | } |
| 770 | EXPORT_SYMBOL(buffer_migrate_page); |
| 771 | #endif |
| 772 | |
| 773 | /* |
| 774 | * Writeback a page to clean the dirty state |
| 775 | */ |
| 776 | static int writeout(struct address_space *mapping, struct page *page) |
| 777 | { |
| 778 | struct writeback_control wbc = { |
| 779 | .sync_mode = WB_SYNC_NONE, |
| 780 | .nr_to_write = 1, |
| 781 | .range_start = 0, |
| 782 | .range_end = LLONG_MAX, |
| 783 | .for_reclaim = 1 |
| 784 | }; |
| 785 | int rc; |
| 786 | |
| 787 | if (!mapping->a_ops->writepage) |
| 788 | /* No write method for the address space */ |
| 789 | return -EINVAL; |
| 790 | |
| 791 | if (!clear_page_dirty_for_io(page)) |
| 792 | /* Someone else already triggered a write */ |
| 793 | return -EAGAIN; |
| 794 | |
| 795 | /* |
| 796 | * A dirty page may imply that the underlying filesystem has |
| 797 | * the page on some queue. So the page must be clean for |
| 798 | * migration. Writeout may mean we loose the lock and the |
| 799 | * page state is no longer what we checked for earlier. |
| 800 | * At this point we know that the migration attempt cannot |
| 801 | * be successful. |
| 802 | */ |
| 803 | remove_migration_ptes(page, page, false); |
| 804 | |
| 805 | rc = mapping->a_ops->writepage(page, &wbc); |
| 806 | |
| 807 | if (rc != AOP_WRITEPAGE_ACTIVATE) |
| 808 | /* unlocked. Relock */ |
| 809 | lock_page(page); |
| 810 | |
| 811 | return (rc < 0) ? -EIO : -EAGAIN; |
| 812 | } |
| 813 | |
| 814 | /* |
| 815 | * Default handling if a filesystem does not provide a migration function. |
| 816 | */ |
| 817 | static int fallback_migrate_page(struct address_space *mapping, |
| 818 | struct page *newpage, struct page *page, enum migrate_mode mode) |
| 819 | { |
| 820 | if (PageDirty(page)) { |
| 821 | /* Only writeback pages in full synchronous migration */ |
| 822 | if (mode != MIGRATE_SYNC) |
| 823 | return -EBUSY; |
| 824 | return writeout(mapping, page); |
| 825 | } |
| 826 | |
| 827 | /* |
| 828 | * Buffers may be managed in a filesystem specific way. |
| 829 | * We must have no buffers or drop them. |
| 830 | */ |
| 831 | if (page_has_private(page) && |
| 832 | !try_to_release_page(page, GFP_KERNEL)) |
| 833 | return -EAGAIN; |
| 834 | |
| 835 | return migrate_page(mapping, newpage, page, mode); |
| 836 | } |
| 837 | |
| 838 | /* |
| 839 | * Move a page to a newly allocated page |
| 840 | * The page is locked and all ptes have been successfully removed. |
| 841 | * |
| 842 | * The new page will have replaced the old page if this function |
| 843 | * is successful. |
| 844 | * |
| 845 | * Return value: |
| 846 | * < 0 - error code |
| 847 | * MIGRATEPAGE_SUCCESS - success |
| 848 | */ |
| 849 | static int move_to_new_page(struct page *newpage, struct page *page, |
| 850 | enum migrate_mode mode) |
| 851 | { |
| 852 | struct address_space *mapping; |
| 853 | int rc = -EAGAIN; |
| 854 | bool is_lru = !__PageMovable(page); |
| 855 | |
| 856 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
| 857 | VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); |
| 858 | |
| 859 | mapping = page_mapping(page); |
| 860 | |
| 861 | if (likely(is_lru)) { |
| 862 | if (!mapping) |
| 863 | rc = migrate_page(mapping, newpage, page, mode); |
| 864 | else if (mapping->a_ops->migratepage) |
| 865 | /* |
| 866 | * Most pages have a mapping and most filesystems |
| 867 | * provide a migratepage callback. Anonymous pages |
| 868 | * are part of swap space which also has its own |
| 869 | * migratepage callback. This is the most common path |
| 870 | * for page migration. |
| 871 | */ |
| 872 | rc = mapping->a_ops->migratepage(mapping, newpage, |
| 873 | page, mode); |
| 874 | else |
| 875 | rc = fallback_migrate_page(mapping, newpage, |
| 876 | page, mode); |
| 877 | } else { |
| 878 | /* |
| 879 | * In case of non-lru page, it could be released after |
| 880 | * isolation step. In that case, we shouldn't try migration. |
| 881 | */ |
| 882 | VM_BUG_ON_PAGE(!PageIsolated(page), page); |
| 883 | if (!PageMovable(page)) { |
| 884 | rc = MIGRATEPAGE_SUCCESS; |
| 885 | __ClearPageIsolated(page); |
| 886 | goto out; |
| 887 | } |
| 888 | |
| 889 | rc = mapping->a_ops->migratepage(mapping, newpage, |
| 890 | page, mode); |
| 891 | WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS && |
| 892 | !PageIsolated(page)); |
| 893 | } |
| 894 | |
| 895 | /* |
| 896 | * When successful, old pagecache page->mapping must be cleared before |
| 897 | * page is freed; but stats require that PageAnon be left as PageAnon. |
| 898 | */ |
| 899 | if (rc == MIGRATEPAGE_SUCCESS) { |
| 900 | if (__PageMovable(page)) { |
| 901 | VM_BUG_ON_PAGE(!PageIsolated(page), page); |
| 902 | |
| 903 | /* |
| 904 | * We clear PG_movable under page_lock so any compactor |
| 905 | * cannot try to migrate this page. |
| 906 | */ |
| 907 | __ClearPageIsolated(page); |
| 908 | } |
| 909 | |
| 910 | /* |
| 911 | * Anonymous and movable page->mapping will be cleard by |
| 912 | * free_pages_prepare so don't reset it here for keeping |
| 913 | * the type to work PageAnon, for example. |
| 914 | */ |
| 915 | if (!PageMappingFlags(page)) |
| 916 | page->mapping = NULL; |
| 917 | } |
| 918 | out: |
| 919 | return rc; |
| 920 | } |
| 921 | |
| 922 | static int __unmap_and_move(struct page *page, struct page *newpage, |
| 923 | int force, enum migrate_mode mode) |
| 924 | { |
| 925 | int rc = -EAGAIN; |
| 926 | int page_was_mapped = 0; |
| 927 | struct anon_vma *anon_vma = NULL; |
| 928 | bool is_lru = !__PageMovable(page); |
| 929 | |
| 930 | if (!trylock_page(page)) { |
| 931 | if (!force || mode == MIGRATE_ASYNC) |
| 932 | goto out; |
| 933 | |
| 934 | /* |
| 935 | * It's not safe for direct compaction to call lock_page. |
| 936 | * For example, during page readahead pages are added locked |
| 937 | * to the LRU. Later, when the IO completes the pages are |
| 938 | * marked uptodate and unlocked. However, the queueing |
| 939 | * could be merging multiple pages for one bio (e.g. |
| 940 | * mpage_readpages). If an allocation happens for the |
| 941 | * second or third page, the process can end up locking |
| 942 | * the same page twice and deadlocking. Rather than |
| 943 | * trying to be clever about what pages can be locked, |
| 944 | * avoid the use of lock_page for direct compaction |
| 945 | * altogether. |
| 946 | */ |
| 947 | if (current->flags & PF_MEMALLOC) |
| 948 | goto out; |
| 949 | |
| 950 | lock_page(page); |
| 951 | } |
| 952 | |
| 953 | if (PageWriteback(page)) { |
| 954 | /* |
| 955 | * Only in the case of a full synchronous migration is it |
| 956 | * necessary to wait for PageWriteback. In the async case, |
| 957 | * the retry loop is too short and in the sync-light case, |
| 958 | * the overhead of stalling is too much |
| 959 | */ |
| 960 | if (mode != MIGRATE_SYNC) { |
| 961 | rc = -EBUSY; |
| 962 | goto out_unlock; |
| 963 | } |
| 964 | if (!force) |
| 965 | goto out_unlock; |
| 966 | wait_on_page_writeback(page); |
| 967 | } |
| 968 | |
| 969 | /* |
| 970 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, |
| 971 | * we cannot notice that anon_vma is freed while we migrates a page. |
| 972 | * This get_anon_vma() delays freeing anon_vma pointer until the end |
| 973 | * of migration. File cache pages are no problem because of page_lock() |
| 974 | * File Caches may use write_page() or lock_page() in migration, then, |
| 975 | * just care Anon page here. |
| 976 | * |
| 977 | * Only page_get_anon_vma() understands the subtleties of |
| 978 | * getting a hold on an anon_vma from outside one of its mms. |
| 979 | * But if we cannot get anon_vma, then we won't need it anyway, |
| 980 | * because that implies that the anon page is no longer mapped |
| 981 | * (and cannot be remapped so long as we hold the page lock). |
| 982 | */ |
| 983 | if (PageAnon(page) && !PageKsm(page)) |
| 984 | anon_vma = page_get_anon_vma(page); |
| 985 | |
| 986 | /* |
| 987 | * Block others from accessing the new page when we get around to |
| 988 | * establishing additional references. We are usually the only one |
| 989 | * holding a reference to newpage at this point. We used to have a BUG |
| 990 | * here if trylock_page(newpage) fails, but would like to allow for |
| 991 | * cases where there might be a race with the previous use of newpage. |
| 992 | * This is much like races on refcount of oldpage: just don't BUG(). |
| 993 | */ |
| 994 | if (unlikely(!trylock_page(newpage))) |
| 995 | goto out_unlock; |
| 996 | |
| 997 | if (unlikely(!is_lru)) { |
| 998 | rc = move_to_new_page(newpage, page, mode); |
| 999 | goto out_unlock_both; |
| 1000 | } |
| 1001 | |
| 1002 | /* |
| 1003 | * Corner case handling: |
| 1004 | * 1. When a new swap-cache page is read into, it is added to the LRU |
| 1005 | * and treated as swapcache but it has no rmap yet. |
| 1006 | * Calling try_to_unmap() against a page->mapping==NULL page will |
| 1007 | * trigger a BUG. So handle it here. |
| 1008 | * 2. An orphaned page (see truncate_complete_page) might have |
| 1009 | * fs-private metadata. The page can be picked up due to memory |
| 1010 | * offlining. Everywhere else except page reclaim, the page is |
| 1011 | * invisible to the vm, so the page can not be migrated. So try to |
| 1012 | * free the metadata, so the page can be freed. |
| 1013 | */ |
| 1014 | if (!page->mapping) { |
| 1015 | VM_BUG_ON_PAGE(PageAnon(page), page); |
| 1016 | if (page_has_private(page)) { |
| 1017 | try_to_free_buffers(page); |
| 1018 | goto out_unlock_both; |
| 1019 | } |
| 1020 | } else if (page_mapped(page)) { |
| 1021 | /* Establish migration ptes */ |
| 1022 | VM_BUG_ON_PAGE(PageAnon(page) && !PageKsm(page) && !anon_vma, |
| 1023 | page); |
| 1024 | try_to_unmap(page, |
| 1025 | TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); |
| 1026 | page_was_mapped = 1; |
| 1027 | } |
| 1028 | |
| 1029 | if (!page_mapped(page)) |
| 1030 | rc = move_to_new_page(newpage, page, mode); |
| 1031 | |
| 1032 | if (page_was_mapped) |
| 1033 | remove_migration_ptes(page, |
| 1034 | rc == MIGRATEPAGE_SUCCESS ? newpage : page, false); |
| 1035 | |
| 1036 | out_unlock_both: |
| 1037 | unlock_page(newpage); |
| 1038 | out_unlock: |
| 1039 | /* Drop an anon_vma reference if we took one */ |
| 1040 | if (anon_vma) |
| 1041 | put_anon_vma(anon_vma); |
| 1042 | unlock_page(page); |
| 1043 | out: |
| 1044 | /* |
| 1045 | * If migration is successful, decrease refcount of the newpage |
| 1046 | * which will not free the page because new page owner increased |
| 1047 | * refcounter. As well, if it is LRU page, add the page to LRU |
| 1048 | * list in here. |
| 1049 | */ |
| 1050 | if (rc == MIGRATEPAGE_SUCCESS) { |
| 1051 | if (unlikely(__PageMovable(newpage))) |
| 1052 | put_page(newpage); |
| 1053 | else |
| 1054 | putback_lru_page(newpage); |
| 1055 | } |
| 1056 | |
| 1057 | return rc; |
| 1058 | } |
| 1059 | |
| 1060 | /* |
| 1061 | * gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move(). Work |
| 1062 | * around it. |
| 1063 | */ |
| 1064 | #if (GCC_VERSION >= 40700 && GCC_VERSION < 40900) && defined(CONFIG_ARM) |
| 1065 | #define ICE_noinline noinline |
| 1066 | #else |
| 1067 | #define ICE_noinline |
| 1068 | #endif |
| 1069 | |
| 1070 | /* |
| 1071 | * Obtain the lock on page, remove all ptes and migrate the page |
| 1072 | * to the newly allocated page in newpage. |
| 1073 | */ |
| 1074 | static ICE_noinline int unmap_and_move(new_page_t get_new_page, |
| 1075 | free_page_t put_new_page, |
| 1076 | unsigned long private, struct page *page, |
| 1077 | int force, enum migrate_mode mode, |
| 1078 | enum migrate_reason reason) |
| 1079 | { |
| 1080 | int rc = MIGRATEPAGE_SUCCESS; |
| 1081 | int *result = NULL; |
| 1082 | struct page *newpage; |
| 1083 | |
| 1084 | newpage = get_new_page(page, private, &result); |
| 1085 | if (!newpage) |
| 1086 | return -ENOMEM; |
| 1087 | |
| 1088 | if (page_count(page) == 1) { |
| 1089 | /* page was freed from under us. So we are done. */ |
| 1090 | ClearPageActive(page); |
| 1091 | ClearPageUnevictable(page); |
| 1092 | if (unlikely(__PageMovable(page))) { |
| 1093 | lock_page(page); |
| 1094 | if (!PageMovable(page)) |
| 1095 | __ClearPageIsolated(page); |
| 1096 | unlock_page(page); |
| 1097 | } |
| 1098 | if (put_new_page) |
| 1099 | put_new_page(newpage, private); |
| 1100 | else |
| 1101 | put_page(newpage); |
| 1102 | goto out; |
| 1103 | } |
| 1104 | |
| 1105 | if (unlikely(PageTransHuge(page))) { |
| 1106 | lock_page(page); |
| 1107 | rc = split_huge_page(page); |
| 1108 | unlock_page(page); |
| 1109 | if (rc) |
| 1110 | goto out; |
| 1111 | } |
| 1112 | |
| 1113 | rc = __unmap_and_move(page, newpage, force, mode); |
| 1114 | if (rc == MIGRATEPAGE_SUCCESS) |
| 1115 | set_page_owner_migrate_reason(newpage, reason); |
| 1116 | |
| 1117 | out: |
| 1118 | if (rc != -EAGAIN) { |
| 1119 | /* |
| 1120 | * A page that has been migrated has all references |
| 1121 | * removed and will be freed. A page that has not been |
| 1122 | * migrated will have kepts its references and be |
| 1123 | * restored. |
| 1124 | */ |
| 1125 | list_del(&page->lru); |
| 1126 | |
| 1127 | /* |
| 1128 | * Compaction can migrate also non-LRU pages which are |
| 1129 | * not accounted to NR_ISOLATED_*. They can be recognized |
| 1130 | * as __PageMovable |
| 1131 | */ |
| 1132 | if (likely(!__PageMovable(page))) |
| 1133 | dec_node_page_state(page, NR_ISOLATED_ANON + |
| 1134 | page_is_file_cache(page)); |
| 1135 | } |
| 1136 | |
| 1137 | /* |
| 1138 | * If migration is successful, releases reference grabbed during |
| 1139 | * isolation. Otherwise, restore the page to right list unless |
| 1140 | * we want to retry. |
| 1141 | */ |
| 1142 | if (rc == MIGRATEPAGE_SUCCESS) { |
| 1143 | put_page(page); |
| 1144 | if (reason == MR_MEMORY_FAILURE) { |
| 1145 | /* |
| 1146 | * Set PG_HWPoison on just freed page |
| 1147 | * intentionally. Although it's rather weird, |
| 1148 | * it's how HWPoison flag works at the moment. |
| 1149 | */ |
| 1150 | if (!test_set_page_hwpoison(page)) |
| 1151 | num_poisoned_pages_inc(); |
| 1152 | } |
| 1153 | } else { |
| 1154 | if (rc != -EAGAIN) { |
| 1155 | if (likely(!__PageMovable(page))) { |
| 1156 | putback_lru_page(page); |
| 1157 | goto put_new; |
| 1158 | } |
| 1159 | |
| 1160 | lock_page(page); |
| 1161 | if (PageMovable(page)) |
| 1162 | putback_movable_page(page); |
| 1163 | else |
| 1164 | __ClearPageIsolated(page); |
| 1165 | unlock_page(page); |
| 1166 | put_page(page); |
| 1167 | } |
| 1168 | put_new: |
| 1169 | if (put_new_page) |
| 1170 | put_new_page(newpage, private); |
| 1171 | else |
| 1172 | put_page(newpage); |
| 1173 | } |
| 1174 | |
| 1175 | if (result) { |
| 1176 | if (rc) |
| 1177 | *result = rc; |
| 1178 | else |
| 1179 | *result = page_to_nid(newpage); |
| 1180 | } |
| 1181 | return rc; |
| 1182 | } |
| 1183 | |
| 1184 | /* |
| 1185 | * Counterpart of unmap_and_move_page() for hugepage migration. |
| 1186 | * |
| 1187 | * This function doesn't wait the completion of hugepage I/O |
| 1188 | * because there is no race between I/O and migration for hugepage. |
| 1189 | * Note that currently hugepage I/O occurs only in direct I/O |
| 1190 | * where no lock is held and PG_writeback is irrelevant, |
| 1191 | * and writeback status of all subpages are counted in the reference |
| 1192 | * count of the head page (i.e. if all subpages of a 2MB hugepage are |
| 1193 | * under direct I/O, the reference of the head page is 512 and a bit more.) |
| 1194 | * This means that when we try to migrate hugepage whose subpages are |
| 1195 | * doing direct I/O, some references remain after try_to_unmap() and |
| 1196 | * hugepage migration fails without data corruption. |
| 1197 | * |
| 1198 | * There is also no race when direct I/O is issued on the page under migration, |
| 1199 | * because then pte is replaced with migration swap entry and direct I/O code |
| 1200 | * will wait in the page fault for migration to complete. |
| 1201 | */ |
| 1202 | static int unmap_and_move_huge_page(new_page_t get_new_page, |
| 1203 | free_page_t put_new_page, unsigned long private, |
| 1204 | struct page *hpage, int force, |
| 1205 | enum migrate_mode mode, int reason) |
| 1206 | { |
| 1207 | int rc = -EAGAIN; |
| 1208 | int *result = NULL; |
| 1209 | int page_was_mapped = 0; |
| 1210 | struct page *new_hpage; |
| 1211 | struct anon_vma *anon_vma = NULL; |
| 1212 | |
| 1213 | /* |
| 1214 | * Movability of hugepages depends on architectures and hugepage size. |
| 1215 | * This check is necessary because some callers of hugepage migration |
| 1216 | * like soft offline and memory hotremove don't walk through page |
| 1217 | * tables or check whether the hugepage is pmd-based or not before |
| 1218 | * kicking migration. |
| 1219 | */ |
| 1220 | if (!hugepage_migration_supported(page_hstate(hpage))) { |
| 1221 | putback_active_hugepage(hpage); |
| 1222 | return -ENOSYS; |
| 1223 | } |
| 1224 | |
| 1225 | new_hpage = get_new_page(hpage, private, &result); |
| 1226 | if (!new_hpage) |
| 1227 | return -ENOMEM; |
| 1228 | |
| 1229 | if (!trylock_page(hpage)) { |
| 1230 | if (!force || mode != MIGRATE_SYNC) |
| 1231 | goto out; |
| 1232 | lock_page(hpage); |
| 1233 | } |
| 1234 | |
| 1235 | if (PageAnon(hpage)) |
| 1236 | anon_vma = page_get_anon_vma(hpage); |
| 1237 | |
| 1238 | if (unlikely(!trylock_page(new_hpage))) |
| 1239 | goto put_anon; |
| 1240 | |
| 1241 | if (page_mapped(hpage)) { |
| 1242 | try_to_unmap(hpage, |
| 1243 | TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); |
| 1244 | page_was_mapped = 1; |
| 1245 | } |
| 1246 | |
| 1247 | if (!page_mapped(hpage)) |
| 1248 | rc = move_to_new_page(new_hpage, hpage, mode); |
| 1249 | |
| 1250 | if (page_was_mapped) |
| 1251 | remove_migration_ptes(hpage, |
| 1252 | rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage, false); |
| 1253 | |
| 1254 | unlock_page(new_hpage); |
| 1255 | |
| 1256 | put_anon: |
| 1257 | if (anon_vma) |
| 1258 | put_anon_vma(anon_vma); |
| 1259 | |
| 1260 | if (rc == MIGRATEPAGE_SUCCESS) { |
| 1261 | hugetlb_cgroup_migrate(hpage, new_hpage); |
| 1262 | put_new_page = NULL; |
| 1263 | set_page_owner_migrate_reason(new_hpage, reason); |
| 1264 | } |
| 1265 | |
| 1266 | unlock_page(hpage); |
| 1267 | out: |
| 1268 | if (rc != -EAGAIN) |
| 1269 | putback_active_hugepage(hpage); |
| 1270 | |
| 1271 | /* |
| 1272 | * If migration was not successful and there's a freeing callback, use |
| 1273 | * it. Otherwise, put_page() will drop the reference grabbed during |
| 1274 | * isolation. |
| 1275 | */ |
| 1276 | if (put_new_page) |
| 1277 | put_new_page(new_hpage, private); |
| 1278 | else |
| 1279 | putback_active_hugepage(new_hpage); |
| 1280 | |
| 1281 | if (result) { |
| 1282 | if (rc) |
| 1283 | *result = rc; |
| 1284 | else |
| 1285 | *result = page_to_nid(new_hpage); |
| 1286 | } |
| 1287 | return rc; |
| 1288 | } |
| 1289 | |
| 1290 | /* |
| 1291 | * migrate_pages - migrate the pages specified in a list, to the free pages |
| 1292 | * supplied as the target for the page migration |
| 1293 | * |
| 1294 | * @from: The list of pages to be migrated. |
| 1295 | * @get_new_page: The function used to allocate free pages to be used |
| 1296 | * as the target of the page migration. |
| 1297 | * @put_new_page: The function used to free target pages if migration |
| 1298 | * fails, or NULL if no special handling is necessary. |
| 1299 | * @private: Private data to be passed on to get_new_page() |
| 1300 | * @mode: The migration mode that specifies the constraints for |
| 1301 | * page migration, if any. |
| 1302 | * @reason: The reason for page migration. |
| 1303 | * |
| 1304 | * The function returns after 10 attempts or if no pages are movable any more |
| 1305 | * because the list has become empty or no retryable pages exist any more. |
| 1306 | * The caller should call putback_movable_pages() to return pages to the LRU |
| 1307 | * or free list only if ret != 0. |
| 1308 | * |
| 1309 | * Returns the number of pages that were not migrated, or an error code. |
| 1310 | */ |
| 1311 | int migrate_pages(struct list_head *from, new_page_t get_new_page, |
| 1312 | free_page_t put_new_page, unsigned long private, |
| 1313 | enum migrate_mode mode, int reason) |
| 1314 | { |
| 1315 | int retry = 1; |
| 1316 | int nr_failed = 0; |
| 1317 | int nr_succeeded = 0; |
| 1318 | int pass = 0; |
| 1319 | struct page *page; |
| 1320 | struct page *page2; |
| 1321 | int swapwrite = current->flags & PF_SWAPWRITE; |
| 1322 | int rc; |
| 1323 | |
| 1324 | if (!swapwrite) |
| 1325 | current->flags |= PF_SWAPWRITE; |
| 1326 | |
| 1327 | for(pass = 0; pass < 10 && retry; pass++) { |
| 1328 | retry = 0; |
| 1329 | |
| 1330 | list_for_each_entry_safe(page, page2, from, lru) { |
| 1331 | cond_resched(); |
| 1332 | |
| 1333 | if (PageHuge(page)) |
| 1334 | rc = unmap_and_move_huge_page(get_new_page, |
| 1335 | put_new_page, private, page, |
| 1336 | pass > 2, mode, reason); |
| 1337 | else |
| 1338 | rc = unmap_and_move(get_new_page, put_new_page, |
| 1339 | private, page, pass > 2, mode, |
| 1340 | reason); |
| 1341 | |
| 1342 | switch(rc) { |
| 1343 | case -ENOMEM: |
| 1344 | nr_failed++; |
| 1345 | goto out; |
| 1346 | case -EAGAIN: |
| 1347 | retry++; |
| 1348 | break; |
| 1349 | case MIGRATEPAGE_SUCCESS: |
| 1350 | nr_succeeded++; |
| 1351 | break; |
| 1352 | default: |
| 1353 | /* |
| 1354 | * Permanent failure (-EBUSY, -ENOSYS, etc.): |
| 1355 | * unlike -EAGAIN case, the failed page is |
| 1356 | * removed from migration page list and not |
| 1357 | * retried in the next outer loop. |
| 1358 | */ |
| 1359 | nr_failed++; |
| 1360 | break; |
| 1361 | } |
| 1362 | } |
| 1363 | } |
| 1364 | nr_failed += retry; |
| 1365 | rc = nr_failed; |
| 1366 | out: |
| 1367 | if (nr_succeeded) |
| 1368 | count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); |
| 1369 | if (nr_failed) |
| 1370 | count_vm_events(PGMIGRATE_FAIL, nr_failed); |
| 1371 | trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason); |
| 1372 | |
| 1373 | if (!swapwrite) |
| 1374 | current->flags &= ~PF_SWAPWRITE; |
| 1375 | |
| 1376 | return rc; |
| 1377 | } |
| 1378 | |
| 1379 | #ifdef CONFIG_NUMA |
| 1380 | /* |
| 1381 | * Move a list of individual pages |
| 1382 | */ |
| 1383 | struct page_to_node { |
| 1384 | unsigned long addr; |
| 1385 | struct page *page; |
| 1386 | int node; |
| 1387 | int status; |
| 1388 | }; |
| 1389 | |
| 1390 | static struct page *new_page_node(struct page *p, unsigned long private, |
| 1391 | int **result) |
| 1392 | { |
| 1393 | struct page_to_node *pm = (struct page_to_node *)private; |
| 1394 | |
| 1395 | while (pm->node != MAX_NUMNODES && pm->page != p) |
| 1396 | pm++; |
| 1397 | |
| 1398 | if (pm->node == MAX_NUMNODES) |
| 1399 | return NULL; |
| 1400 | |
| 1401 | *result = &pm->status; |
| 1402 | |
| 1403 | if (PageHuge(p)) |
| 1404 | return alloc_huge_page_node(page_hstate(compound_head(p)), |
| 1405 | pm->node); |
| 1406 | else |
| 1407 | return __alloc_pages_node(pm->node, |
| 1408 | GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 0); |
| 1409 | } |
| 1410 | |
| 1411 | /* |
| 1412 | * Move a set of pages as indicated in the pm array. The addr |
| 1413 | * field must be set to the virtual address of the page to be moved |
| 1414 | * and the node number must contain a valid target node. |
| 1415 | * The pm array ends with node = MAX_NUMNODES. |
| 1416 | */ |
| 1417 | static int do_move_page_to_node_array(struct mm_struct *mm, |
| 1418 | struct page_to_node *pm, |
| 1419 | int migrate_all) |
| 1420 | { |
| 1421 | int err; |
| 1422 | struct page_to_node *pp; |
| 1423 | LIST_HEAD(pagelist); |
| 1424 | |
| 1425 | down_read(&mm->mmap_sem); |
| 1426 | |
| 1427 | /* |
| 1428 | * Build a list of pages to migrate |
| 1429 | */ |
| 1430 | for (pp = pm; pp->node != MAX_NUMNODES; pp++) { |
| 1431 | struct vm_area_struct *vma; |
| 1432 | struct page *page; |
| 1433 | |
| 1434 | err = -EFAULT; |
| 1435 | vma = find_vma(mm, pp->addr); |
| 1436 | if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma)) |
| 1437 | goto set_status; |
| 1438 | |
| 1439 | /* FOLL_DUMP to ignore special (like zero) pages */ |
| 1440 | page = follow_page(vma, pp->addr, |
| 1441 | FOLL_GET | FOLL_SPLIT | FOLL_DUMP); |
| 1442 | |
| 1443 | err = PTR_ERR(page); |
| 1444 | if (IS_ERR(page)) |
| 1445 | goto set_status; |
| 1446 | |
| 1447 | err = -ENOENT; |
| 1448 | if (!page) |
| 1449 | goto set_status; |
| 1450 | |
| 1451 | pp->page = page; |
| 1452 | err = page_to_nid(page); |
| 1453 | |
| 1454 | if (err == pp->node) |
| 1455 | /* |
| 1456 | * Node already in the right place |
| 1457 | */ |
| 1458 | goto put_and_set; |
| 1459 | |
| 1460 | err = -EACCES; |
| 1461 | if (page_mapcount(page) > 1 && |
| 1462 | !migrate_all) |
| 1463 | goto put_and_set; |
| 1464 | |
| 1465 | if (PageHuge(page)) { |
| 1466 | if (PageHead(page)) |
| 1467 | isolate_huge_page(page, &pagelist); |
| 1468 | goto put_and_set; |
| 1469 | } |
| 1470 | |
| 1471 | err = isolate_lru_page(page); |
| 1472 | if (!err) { |
| 1473 | list_add_tail(&page->lru, &pagelist); |
| 1474 | inc_node_page_state(page, NR_ISOLATED_ANON + |
| 1475 | page_is_file_cache(page)); |
| 1476 | } |
| 1477 | put_and_set: |
| 1478 | /* |
| 1479 | * Either remove the duplicate refcount from |
| 1480 | * isolate_lru_page() or drop the page ref if it was |
| 1481 | * not isolated. |
| 1482 | */ |
| 1483 | put_page(page); |
| 1484 | set_status: |
| 1485 | pp->status = err; |
| 1486 | } |
| 1487 | |
| 1488 | err = 0; |
| 1489 | if (!list_empty(&pagelist)) { |
| 1490 | err = migrate_pages(&pagelist, new_page_node, NULL, |
| 1491 | (unsigned long)pm, MIGRATE_SYNC, MR_SYSCALL); |
| 1492 | if (err) |
| 1493 | putback_movable_pages(&pagelist); |
| 1494 | } |
| 1495 | |
| 1496 | up_read(&mm->mmap_sem); |
| 1497 | return err; |
| 1498 | } |
| 1499 | |
| 1500 | /* |
| 1501 | * Migrate an array of page address onto an array of nodes and fill |
| 1502 | * the corresponding array of status. |
| 1503 | */ |
| 1504 | static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, |
| 1505 | unsigned long nr_pages, |
| 1506 | const void __user * __user *pages, |
| 1507 | const int __user *nodes, |
| 1508 | int __user *status, int flags) |
| 1509 | { |
| 1510 | struct page_to_node *pm; |
| 1511 | unsigned long chunk_nr_pages; |
| 1512 | unsigned long chunk_start; |
| 1513 | int err; |
| 1514 | |
| 1515 | err = -ENOMEM; |
| 1516 | pm = (struct page_to_node *)__get_free_page(GFP_KERNEL); |
| 1517 | if (!pm) |
| 1518 | goto out; |
| 1519 | |
| 1520 | migrate_prep(); |
| 1521 | |
| 1522 | /* |
| 1523 | * Store a chunk of page_to_node array in a page, |
| 1524 | * but keep the last one as a marker |
| 1525 | */ |
| 1526 | chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1; |
| 1527 | |
| 1528 | for (chunk_start = 0; |
| 1529 | chunk_start < nr_pages; |
| 1530 | chunk_start += chunk_nr_pages) { |
| 1531 | int j; |
| 1532 | |
| 1533 | if (chunk_start + chunk_nr_pages > nr_pages) |
| 1534 | chunk_nr_pages = nr_pages - chunk_start; |
| 1535 | |
| 1536 | /* fill the chunk pm with addrs and nodes from user-space */ |
| 1537 | for (j = 0; j < chunk_nr_pages; j++) { |
| 1538 | const void __user *p; |
| 1539 | int node; |
| 1540 | |
| 1541 | err = -EFAULT; |
| 1542 | if (get_user(p, pages + j + chunk_start)) |
| 1543 | goto out_pm; |
| 1544 | pm[j].addr = (unsigned long) p; |
| 1545 | |
| 1546 | if (get_user(node, nodes + j + chunk_start)) |
| 1547 | goto out_pm; |
| 1548 | |
| 1549 | err = -ENODEV; |
| 1550 | if (node < 0 || node >= MAX_NUMNODES) |
| 1551 | goto out_pm; |
| 1552 | |
| 1553 | if (!node_state(node, N_MEMORY)) |
| 1554 | goto out_pm; |
| 1555 | |
| 1556 | err = -EACCES; |
| 1557 | if (!node_isset(node, task_nodes)) |
| 1558 | goto out_pm; |
| 1559 | |
| 1560 | pm[j].node = node; |
| 1561 | } |
| 1562 | |
| 1563 | /* End marker for this chunk */ |
| 1564 | pm[chunk_nr_pages].node = MAX_NUMNODES; |
| 1565 | |
| 1566 | /* Migrate this chunk */ |
| 1567 | err = do_move_page_to_node_array(mm, pm, |
| 1568 | flags & MPOL_MF_MOVE_ALL); |
| 1569 | if (err < 0) |
| 1570 | goto out_pm; |
| 1571 | |
| 1572 | /* Return status information */ |
| 1573 | for (j = 0; j < chunk_nr_pages; j++) |
| 1574 | if (put_user(pm[j].status, status + j + chunk_start)) { |
| 1575 | err = -EFAULT; |
| 1576 | goto out_pm; |
| 1577 | } |
| 1578 | } |
| 1579 | err = 0; |
| 1580 | |
| 1581 | out_pm: |
| 1582 | free_page((unsigned long)pm); |
| 1583 | out: |
| 1584 | return err; |
| 1585 | } |
| 1586 | |
| 1587 | /* |
| 1588 | * Determine the nodes of an array of pages and store it in an array of status. |
| 1589 | */ |
| 1590 | static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, |
| 1591 | const void __user **pages, int *status) |
| 1592 | { |
| 1593 | unsigned long i; |
| 1594 | |
| 1595 | down_read(&mm->mmap_sem); |
| 1596 | |
| 1597 | for (i = 0; i < nr_pages; i++) { |
| 1598 | unsigned long addr = (unsigned long)(*pages); |
| 1599 | struct vm_area_struct *vma; |
| 1600 | struct page *page; |
| 1601 | int err = -EFAULT; |
| 1602 | |
| 1603 | vma = find_vma(mm, addr); |
| 1604 | if (!vma || addr < vma->vm_start) |
| 1605 | goto set_status; |
| 1606 | |
| 1607 | /* FOLL_DUMP to ignore special (like zero) pages */ |
| 1608 | page = follow_page(vma, addr, FOLL_DUMP); |
| 1609 | |
| 1610 | err = PTR_ERR(page); |
| 1611 | if (IS_ERR(page)) |
| 1612 | goto set_status; |
| 1613 | |
| 1614 | err = page ? page_to_nid(page) : -ENOENT; |
| 1615 | set_status: |
| 1616 | *status = err; |
| 1617 | |
| 1618 | pages++; |
| 1619 | status++; |
| 1620 | } |
| 1621 | |
| 1622 | up_read(&mm->mmap_sem); |
| 1623 | } |
| 1624 | |
| 1625 | /* |
| 1626 | * Determine the nodes of a user array of pages and store it in |
| 1627 | * a user array of status. |
| 1628 | */ |
| 1629 | static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, |
| 1630 | const void __user * __user *pages, |
| 1631 | int __user *status) |
| 1632 | { |
| 1633 | #define DO_PAGES_STAT_CHUNK_NR 16 |
| 1634 | const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; |
| 1635 | int chunk_status[DO_PAGES_STAT_CHUNK_NR]; |
| 1636 | |
| 1637 | while (nr_pages) { |
| 1638 | unsigned long chunk_nr; |
| 1639 | |
| 1640 | chunk_nr = nr_pages; |
| 1641 | if (chunk_nr > DO_PAGES_STAT_CHUNK_NR) |
| 1642 | chunk_nr = DO_PAGES_STAT_CHUNK_NR; |
| 1643 | |
| 1644 | if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages))) |
| 1645 | break; |
| 1646 | |
| 1647 | do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); |
| 1648 | |
| 1649 | if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status))) |
| 1650 | break; |
| 1651 | |
| 1652 | pages += chunk_nr; |
| 1653 | status += chunk_nr; |
| 1654 | nr_pages -= chunk_nr; |
| 1655 | } |
| 1656 | return nr_pages ? -EFAULT : 0; |
| 1657 | } |
| 1658 | |
| 1659 | /* |
| 1660 | * Move a list of pages in the address space of the currently executing |
| 1661 | * process. |
| 1662 | */ |
| 1663 | SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, |
| 1664 | const void __user * __user *, pages, |
| 1665 | const int __user *, nodes, |
| 1666 | int __user *, status, int, flags) |
| 1667 | { |
| 1668 | const struct cred *cred = current_cred(), *tcred; |
| 1669 | struct task_struct *task; |
| 1670 | struct mm_struct *mm; |
| 1671 | int err; |
| 1672 | nodemask_t task_nodes; |
| 1673 | |
| 1674 | /* Check flags */ |
| 1675 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) |
| 1676 | return -EINVAL; |
| 1677 | |
| 1678 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) |
| 1679 | return -EPERM; |
| 1680 | |
| 1681 | /* Find the mm_struct */ |
| 1682 | rcu_read_lock(); |
| 1683 | task = pid ? find_task_by_vpid(pid) : current; |
| 1684 | if (!task) { |
| 1685 | rcu_read_unlock(); |
| 1686 | return -ESRCH; |
| 1687 | } |
| 1688 | get_task_struct(task); |
| 1689 | |
| 1690 | /* |
| 1691 | * Check if this process has the right to modify the specified |
| 1692 | * process. The right exists if the process has administrative |
| 1693 | * capabilities, superuser privileges or the same |
| 1694 | * userid as the target process. |
| 1695 | */ |
| 1696 | tcred = __task_cred(task); |
| 1697 | if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) && |
| 1698 | !uid_eq(cred->uid, tcred->suid) && !uid_eq(cred->uid, tcred->uid) && |
| 1699 | !capable(CAP_SYS_NICE)) { |
| 1700 | rcu_read_unlock(); |
| 1701 | err = -EPERM; |
| 1702 | goto out; |
| 1703 | } |
| 1704 | rcu_read_unlock(); |
| 1705 | |
| 1706 | err = security_task_movememory(task); |
| 1707 | if (err) |
| 1708 | goto out; |
| 1709 | |
| 1710 | task_nodes = cpuset_mems_allowed(task); |
| 1711 | mm = get_task_mm(task); |
| 1712 | put_task_struct(task); |
| 1713 | |
| 1714 | if (!mm) |
| 1715 | return -EINVAL; |
| 1716 | |
| 1717 | if (nodes) |
| 1718 | err = do_pages_move(mm, task_nodes, nr_pages, pages, |
| 1719 | nodes, status, flags); |
| 1720 | else |
| 1721 | err = do_pages_stat(mm, nr_pages, pages, status); |
| 1722 | |
| 1723 | mmput(mm); |
| 1724 | return err; |
| 1725 | |
| 1726 | out: |
| 1727 | put_task_struct(task); |
| 1728 | return err; |
| 1729 | } |
| 1730 | |
| 1731 | #ifdef CONFIG_NUMA_BALANCING |
| 1732 | /* |
| 1733 | * Returns true if this is a safe migration target node for misplaced NUMA |
| 1734 | * pages. Currently it only checks the watermarks which crude |
| 1735 | */ |
| 1736 | static bool migrate_balanced_pgdat(struct pglist_data *pgdat, |
| 1737 | unsigned long nr_migrate_pages) |
| 1738 | { |
| 1739 | int z; |
| 1740 | |
| 1741 | if (!pgdat_reclaimable(pgdat)) |
| 1742 | return false; |
| 1743 | |
| 1744 | for (z = pgdat->nr_zones - 1; z >= 0; z--) { |
| 1745 | struct zone *zone = pgdat->node_zones + z; |
| 1746 | |
| 1747 | if (!populated_zone(zone)) |
| 1748 | continue; |
| 1749 | |
| 1750 | /* Avoid waking kswapd by allocating pages_to_migrate pages. */ |
| 1751 | if (!zone_watermark_ok(zone, 0, |
| 1752 | high_wmark_pages(zone) + |
| 1753 | nr_migrate_pages, |
| 1754 | 0, 0)) |
| 1755 | continue; |
| 1756 | return true; |
| 1757 | } |
| 1758 | return false; |
| 1759 | } |
| 1760 | |
| 1761 | static struct page *alloc_misplaced_dst_page(struct page *page, |
| 1762 | unsigned long data, |
| 1763 | int **result) |
| 1764 | { |
| 1765 | int nid = (int) data; |
| 1766 | struct page *newpage; |
| 1767 | |
| 1768 | newpage = __alloc_pages_node(nid, |
| 1769 | (GFP_HIGHUSER_MOVABLE | |
| 1770 | __GFP_THISNODE | __GFP_NOMEMALLOC | |
| 1771 | __GFP_NORETRY | __GFP_NOWARN) & |
| 1772 | ~__GFP_RECLAIM, 0); |
| 1773 | |
| 1774 | return newpage; |
| 1775 | } |
| 1776 | |
| 1777 | /* |
| 1778 | * page migration rate limiting control. |
| 1779 | * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs |
| 1780 | * window of time. Default here says do not migrate more than 1280M per second. |
| 1781 | */ |
| 1782 | static unsigned int migrate_interval_millisecs __read_mostly = 100; |
| 1783 | static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT); |
| 1784 | |
| 1785 | /* Returns true if the node is migrate rate-limited after the update */ |
| 1786 | static bool numamigrate_update_ratelimit(pg_data_t *pgdat, |
| 1787 | unsigned long nr_pages) |
| 1788 | { |
| 1789 | /* |
| 1790 | * Rate-limit the amount of data that is being migrated to a node. |
| 1791 | * Optimal placement is no good if the memory bus is saturated and |
| 1792 | * all the time is being spent migrating! |
| 1793 | */ |
| 1794 | if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) { |
| 1795 | spin_lock(&pgdat->numabalancing_migrate_lock); |
| 1796 | pgdat->numabalancing_migrate_nr_pages = 0; |
| 1797 | pgdat->numabalancing_migrate_next_window = jiffies + |
| 1798 | msecs_to_jiffies(migrate_interval_millisecs); |
| 1799 | spin_unlock(&pgdat->numabalancing_migrate_lock); |
| 1800 | } |
| 1801 | if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) { |
| 1802 | trace_mm_numa_migrate_ratelimit(current, pgdat->node_id, |
| 1803 | nr_pages); |
| 1804 | return true; |
| 1805 | } |
| 1806 | |
| 1807 | /* |
| 1808 | * This is an unlocked non-atomic update so errors are possible. |
| 1809 | * The consequences are failing to migrate when we potentiall should |
| 1810 | * have which is not severe enough to warrant locking. If it is ever |
| 1811 | * a problem, it can be converted to a per-cpu counter. |
| 1812 | */ |
| 1813 | pgdat->numabalancing_migrate_nr_pages += nr_pages; |
| 1814 | return false; |
| 1815 | } |
| 1816 | |
| 1817 | static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) |
| 1818 | { |
| 1819 | int page_lru; |
| 1820 | |
| 1821 | VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page); |
| 1822 | |
| 1823 | /* Avoid migrating to a node that is nearly full */ |
| 1824 | if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page))) |
| 1825 | return 0; |
| 1826 | |
| 1827 | if (isolate_lru_page(page)) |
| 1828 | return 0; |
| 1829 | |
| 1830 | /* |
| 1831 | * migrate_misplaced_transhuge_page() skips page migration's usual |
| 1832 | * check on page_count(), so we must do it here, now that the page |
| 1833 | * has been isolated: a GUP pin, or any other pin, prevents migration. |
| 1834 | * The expected page count is 3: 1 for page's mapcount and 1 for the |
| 1835 | * caller's pin and 1 for the reference taken by isolate_lru_page(). |
| 1836 | */ |
| 1837 | if (PageTransHuge(page) && page_count(page) != 3) { |
| 1838 | putback_lru_page(page); |
| 1839 | return 0; |
| 1840 | } |
| 1841 | |
| 1842 | page_lru = page_is_file_cache(page); |
| 1843 | mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_lru, |
| 1844 | hpage_nr_pages(page)); |
| 1845 | |
| 1846 | /* |
| 1847 | * Isolating the page has taken another reference, so the |
| 1848 | * caller's reference can be safely dropped without the page |
| 1849 | * disappearing underneath us during migration. |
| 1850 | */ |
| 1851 | put_page(page); |
| 1852 | return 1; |
| 1853 | } |
| 1854 | |
| 1855 | bool pmd_trans_migrating(pmd_t pmd) |
| 1856 | { |
| 1857 | struct page *page = pmd_page(pmd); |
| 1858 | return PageLocked(page); |
| 1859 | } |
| 1860 | |
| 1861 | /* |
| 1862 | * Attempt to migrate a misplaced page to the specified destination |
| 1863 | * node. Caller is expected to have an elevated reference count on |
| 1864 | * the page that will be dropped by this function before returning. |
| 1865 | */ |
| 1866 | int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma, |
| 1867 | int node) |
| 1868 | { |
| 1869 | pg_data_t *pgdat = NODE_DATA(node); |
| 1870 | int isolated; |
| 1871 | int nr_remaining; |
| 1872 | LIST_HEAD(migratepages); |
| 1873 | |
| 1874 | /* |
| 1875 | * Don't migrate file pages that are mapped in multiple processes |
| 1876 | * with execute permissions as they are probably shared libraries. |
| 1877 | */ |
| 1878 | if (page_mapcount(page) != 1 && page_is_file_cache(page) && |
| 1879 | (vma->vm_flags & VM_EXEC)) |
| 1880 | goto out; |
| 1881 | |
| 1882 | /* |
| 1883 | * Rate-limit the amount of data that is being migrated to a node. |
| 1884 | * Optimal placement is no good if the memory bus is saturated and |
| 1885 | * all the time is being spent migrating! |
| 1886 | */ |
| 1887 | if (numamigrate_update_ratelimit(pgdat, 1)) |
| 1888 | goto out; |
| 1889 | |
| 1890 | isolated = numamigrate_isolate_page(pgdat, page); |
| 1891 | if (!isolated) |
| 1892 | goto out; |
| 1893 | |
| 1894 | list_add(&page->lru, &migratepages); |
| 1895 | nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page, |
| 1896 | NULL, node, MIGRATE_ASYNC, |
| 1897 | MR_NUMA_MISPLACED); |
| 1898 | if (nr_remaining) { |
| 1899 | if (!list_empty(&migratepages)) { |
| 1900 | list_del(&page->lru); |
| 1901 | dec_node_page_state(page, NR_ISOLATED_ANON + |
| 1902 | page_is_file_cache(page)); |
| 1903 | putback_lru_page(page); |
| 1904 | } |
| 1905 | isolated = 0; |
| 1906 | } else |
| 1907 | count_vm_numa_event(NUMA_PAGE_MIGRATE); |
| 1908 | BUG_ON(!list_empty(&migratepages)); |
| 1909 | return isolated; |
| 1910 | |
| 1911 | out: |
| 1912 | put_page(page); |
| 1913 | return 0; |
| 1914 | } |
| 1915 | #endif /* CONFIG_NUMA_BALANCING */ |
| 1916 | |
| 1917 | #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE) |
| 1918 | /* |
| 1919 | * Migrates a THP to a given target node. page must be locked and is unlocked |
| 1920 | * before returning. |
| 1921 | */ |
| 1922 | int migrate_misplaced_transhuge_page(struct mm_struct *mm, |
| 1923 | struct vm_area_struct *vma, |
| 1924 | pmd_t *pmd, pmd_t entry, |
| 1925 | unsigned long address, |
| 1926 | struct page *page, int node) |
| 1927 | { |
| 1928 | spinlock_t *ptl; |
| 1929 | pg_data_t *pgdat = NODE_DATA(node); |
| 1930 | int isolated = 0; |
| 1931 | struct page *new_page = NULL; |
| 1932 | int page_lru = page_is_file_cache(page); |
| 1933 | unsigned long mmun_start = address & HPAGE_PMD_MASK; |
| 1934 | unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE; |
| 1935 | pmd_t orig_entry; |
| 1936 | |
| 1937 | /* |
| 1938 | * Rate-limit the amount of data that is being migrated to a node. |
| 1939 | * Optimal placement is no good if the memory bus is saturated and |
| 1940 | * all the time is being spent migrating! |
| 1941 | */ |
| 1942 | if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR)) |
| 1943 | goto out_dropref; |
| 1944 | |
| 1945 | new_page = alloc_pages_node(node, |
| 1946 | (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE), |
| 1947 | HPAGE_PMD_ORDER); |
| 1948 | if (!new_page) |
| 1949 | goto out_fail; |
| 1950 | prep_transhuge_page(new_page); |
| 1951 | |
| 1952 | isolated = numamigrate_isolate_page(pgdat, page); |
| 1953 | if (!isolated) { |
| 1954 | put_page(new_page); |
| 1955 | goto out_fail; |
| 1956 | } |
| 1957 | /* |
| 1958 | * We are not sure a pending tlb flush here is for a huge page |
| 1959 | * mapping or not. Hence use the tlb range variant |
| 1960 | */ |
| 1961 | if (mm_tlb_flush_pending(mm)) |
| 1962 | flush_tlb_range(vma, mmun_start, mmun_end); |
| 1963 | |
| 1964 | /* Prepare a page as a migration target */ |
| 1965 | __SetPageLocked(new_page); |
| 1966 | __SetPageSwapBacked(new_page); |
| 1967 | |
| 1968 | /* anon mapping, we can simply copy page->mapping to the new page: */ |
| 1969 | new_page->mapping = page->mapping; |
| 1970 | new_page->index = page->index; |
| 1971 | migrate_page_copy(new_page, page); |
| 1972 | WARN_ON(PageLRU(new_page)); |
| 1973 | |
| 1974 | /* Recheck the target PMD */ |
| 1975 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
| 1976 | ptl = pmd_lock(mm, pmd); |
| 1977 | if (unlikely(!pmd_same(*pmd, entry) || page_count(page) != 2)) { |
| 1978 | fail_putback: |
| 1979 | spin_unlock(ptl); |
| 1980 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
| 1981 | |
| 1982 | /* Reverse changes made by migrate_page_copy() */ |
| 1983 | if (TestClearPageActive(new_page)) |
| 1984 | SetPageActive(page); |
| 1985 | if (TestClearPageUnevictable(new_page)) |
| 1986 | SetPageUnevictable(page); |
| 1987 | |
| 1988 | unlock_page(new_page); |
| 1989 | put_page(new_page); /* Free it */ |
| 1990 | |
| 1991 | /* Retake the callers reference and putback on LRU */ |
| 1992 | get_page(page); |
| 1993 | putback_lru_page(page); |
| 1994 | mod_node_page_state(page_pgdat(page), |
| 1995 | NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR); |
| 1996 | |
| 1997 | goto out_unlock; |
| 1998 | } |
| 1999 | |
| 2000 | orig_entry = *pmd; |
| 2001 | entry = mk_huge_pmd(new_page, vma->vm_page_prot); |
| 2002 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); |
| 2003 | |
| 2004 | /* |
| 2005 | * Clear the old entry under pagetable lock and establish the new PTE. |
| 2006 | * Any parallel GUP will either observe the old page blocking on the |
| 2007 | * page lock, block on the page table lock or observe the new page. |
| 2008 | * The SetPageUptodate on the new page and page_add_new_anon_rmap |
| 2009 | * guarantee the copy is visible before the pagetable update. |
| 2010 | */ |
| 2011 | flush_cache_range(vma, mmun_start, mmun_end); |
| 2012 | page_add_anon_rmap(new_page, vma, mmun_start, true); |
| 2013 | pmdp_huge_clear_flush_notify(vma, mmun_start, pmd); |
| 2014 | set_pmd_at(mm, mmun_start, pmd, entry); |
| 2015 | update_mmu_cache_pmd(vma, address, &entry); |
| 2016 | |
| 2017 | if (page_count(page) != 2) { |
| 2018 | set_pmd_at(mm, mmun_start, pmd, orig_entry); |
| 2019 | flush_pmd_tlb_range(vma, mmun_start, mmun_end); |
| 2020 | mmu_notifier_invalidate_range(mm, mmun_start, mmun_end); |
| 2021 | update_mmu_cache_pmd(vma, address, &entry); |
| 2022 | page_remove_rmap(new_page, true); |
| 2023 | goto fail_putback; |
| 2024 | } |
| 2025 | |
| 2026 | mlock_migrate_page(new_page, page); |
| 2027 | page_remove_rmap(page, true); |
| 2028 | set_page_owner_migrate_reason(new_page, MR_NUMA_MISPLACED); |
| 2029 | |
| 2030 | spin_unlock(ptl); |
| 2031 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
| 2032 | |
| 2033 | /* Take an "isolate" reference and put new page on the LRU. */ |
| 2034 | get_page(new_page); |
| 2035 | putback_lru_page(new_page); |
| 2036 | |
| 2037 | unlock_page(new_page); |
| 2038 | unlock_page(page); |
| 2039 | put_page(page); /* Drop the rmap reference */ |
| 2040 | put_page(page); /* Drop the LRU isolation reference */ |
| 2041 | |
| 2042 | count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR); |
| 2043 | count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR); |
| 2044 | |
| 2045 | mod_node_page_state(page_pgdat(page), |
| 2046 | NR_ISOLATED_ANON + page_lru, |
| 2047 | -HPAGE_PMD_NR); |
| 2048 | return isolated; |
| 2049 | |
| 2050 | out_fail: |
| 2051 | count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); |
| 2052 | out_dropref: |
| 2053 | ptl = pmd_lock(mm, pmd); |
| 2054 | if (pmd_same(*pmd, entry)) { |
| 2055 | entry = pmd_modify(entry, vma->vm_page_prot); |
| 2056 | set_pmd_at(mm, mmun_start, pmd, entry); |
| 2057 | update_mmu_cache_pmd(vma, address, &entry); |
| 2058 | } |
| 2059 | spin_unlock(ptl); |
| 2060 | |
| 2061 | out_unlock: |
| 2062 | unlock_page(page); |
| 2063 | put_page(page); |
| 2064 | return 0; |
| 2065 | } |
| 2066 | #endif /* CONFIG_NUMA_BALANCING */ |
| 2067 | |
| 2068 | #endif /* CONFIG_NUMA */ |