| 1 | /* |
| 2 | * Memory Migration functionality - linux/mm/migration.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/memcontrol.h> |
| 34 | #include <linux/syscalls.h> |
| 35 | #include <linux/hugetlb.h> |
| 36 | #include <linux/hugetlb_cgroup.h> |
| 37 | #include <linux/gfp.h> |
| 38 | #include <linux/balloon_compaction.h> |
| 39 | #include <linux/mmu_notifier.h> |
| 40 | |
| 41 | #include <asm/tlbflush.h> |
| 42 | |
| 43 | #define CREATE_TRACE_POINTS |
| 44 | #include <trace/events/migrate.h> |
| 45 | |
| 46 | #include "internal.h" |
| 47 | |
| 48 | /* |
| 49 | * migrate_prep() needs to be called before we start compiling a list of pages |
| 50 | * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is |
| 51 | * undesirable, use migrate_prep_local() |
| 52 | */ |
| 53 | int migrate_prep(void) |
| 54 | { |
| 55 | /* |
| 56 | * Clear the LRU lists so pages can be isolated. |
| 57 | * Note that pages may be moved off the LRU after we have |
| 58 | * drained them. Those pages will fail to migrate like other |
| 59 | * pages that may be busy. |
| 60 | */ |
| 61 | lru_add_drain_all(); |
| 62 | |
| 63 | return 0; |
| 64 | } |
| 65 | |
| 66 | /* Do the necessary work of migrate_prep but not if it involves other CPUs */ |
| 67 | int migrate_prep_local(void) |
| 68 | { |
| 69 | lru_add_drain(); |
| 70 | |
| 71 | return 0; |
| 72 | } |
| 73 | |
| 74 | /* |
| 75 | * Put previously isolated pages back onto the appropriate lists |
| 76 | * from where they were once taken off for compaction/migration. |
| 77 | * |
| 78 | * This function shall be used whenever the isolated pageset has been |
| 79 | * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range() |
| 80 | * and isolate_huge_page(). |
| 81 | */ |
| 82 | void putback_movable_pages(struct list_head *l) |
| 83 | { |
| 84 | struct page *page; |
| 85 | struct page *page2; |
| 86 | |
| 87 | list_for_each_entry_safe(page, page2, l, lru) { |
| 88 | if (unlikely(PageHuge(page))) { |
| 89 | putback_active_hugepage(page); |
| 90 | continue; |
| 91 | } |
| 92 | list_del(&page->lru); |
| 93 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
| 94 | page_is_file_cache(page)); |
| 95 | if (unlikely(isolated_balloon_page(page))) |
| 96 | balloon_page_putback(page); |
| 97 | else |
| 98 | putback_lru_page(page); |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | /* |
| 103 | * Restore a potential migration pte to a working pte entry |
| 104 | */ |
| 105 | static int remove_migration_pte(struct page *new, struct vm_area_struct *vma, |
| 106 | unsigned long addr, void *old) |
| 107 | { |
| 108 | struct mm_struct *mm = vma->vm_mm; |
| 109 | swp_entry_t entry; |
| 110 | pmd_t *pmd; |
| 111 | pte_t *ptep, pte; |
| 112 | spinlock_t *ptl; |
| 113 | |
| 114 | if (unlikely(PageHuge(new))) { |
| 115 | ptep = huge_pte_offset(mm, addr); |
| 116 | if (!ptep) |
| 117 | goto out; |
| 118 | ptl = huge_pte_lockptr(hstate_vma(vma), mm, ptep); |
| 119 | } else { |
| 120 | pmd = mm_find_pmd(mm, addr); |
| 121 | if (!pmd) |
| 122 | goto out; |
| 123 | if (pmd_trans_huge(*pmd)) |
| 124 | goto out; |
| 125 | |
| 126 | ptep = pte_offset_map(pmd, addr); |
| 127 | |
| 128 | /* |
| 129 | * Peek to check is_swap_pte() before taking ptlock? No, we |
| 130 | * can race mremap's move_ptes(), which skips anon_vma lock. |
| 131 | */ |
| 132 | |
| 133 | ptl = pte_lockptr(mm, pmd); |
| 134 | } |
| 135 | |
| 136 | spin_lock(ptl); |
| 137 | pte = *ptep; |
| 138 | if (!is_swap_pte(pte)) |
| 139 | goto unlock; |
| 140 | |
| 141 | entry = pte_to_swp_entry(pte); |
| 142 | |
| 143 | if (!is_migration_entry(entry) || |
| 144 | migration_entry_to_page(entry) != old) |
| 145 | goto unlock; |
| 146 | |
| 147 | get_page(new); |
| 148 | pte = pte_mkold(mk_pte(new, vma->vm_page_prot)); |
| 149 | if (pte_swp_soft_dirty(*ptep)) |
| 150 | pte = pte_mksoft_dirty(pte); |
| 151 | if (is_write_migration_entry(entry)) |
| 152 | pte = pte_mkwrite(pte); |
| 153 | #ifdef CONFIG_HUGETLB_PAGE |
| 154 | if (PageHuge(new)) { |
| 155 | pte = pte_mkhuge(pte); |
| 156 | pte = arch_make_huge_pte(pte, vma, new, 0); |
| 157 | } |
| 158 | #endif |
| 159 | flush_dcache_page(new); |
| 160 | set_pte_at(mm, addr, ptep, pte); |
| 161 | |
| 162 | if (PageHuge(new)) { |
| 163 | if (PageAnon(new)) |
| 164 | hugepage_add_anon_rmap(new, vma, addr); |
| 165 | else |
| 166 | page_dup_rmap(new); |
| 167 | } else if (PageAnon(new)) |
| 168 | page_add_anon_rmap(new, vma, addr); |
| 169 | else |
| 170 | page_add_file_rmap(new); |
| 171 | |
| 172 | /* No need to invalidate - it was non-present before */ |
| 173 | update_mmu_cache(vma, addr, ptep); |
| 174 | unlock: |
| 175 | pte_unmap_unlock(ptep, ptl); |
| 176 | out: |
| 177 | return SWAP_AGAIN; |
| 178 | } |
| 179 | |
| 180 | /* |
| 181 | * Congratulations to trinity for discovering this bug. |
| 182 | * mm/fremap.c's remap_file_pages() accepts any range within a single vma to |
| 183 | * convert that vma to VM_NONLINEAR; and generic_file_remap_pages() will then |
| 184 | * replace the specified range by file ptes throughout (maybe populated after). |
| 185 | * If page migration finds a page within that range, while it's still located |
| 186 | * by vma_interval_tree rather than lost to i_mmap_nonlinear list, no problem: |
| 187 | * zap_pte() clears the temporary migration entry before mmap_sem is dropped. |
| 188 | * But if the migrating page is in a part of the vma outside the range to be |
| 189 | * remapped, then it will not be cleared, and remove_migration_ptes() needs to |
| 190 | * deal with it. Fortunately, this part of the vma is of course still linear, |
| 191 | * so we just need to use linear location on the nonlinear list. |
| 192 | */ |
| 193 | static int remove_linear_migration_ptes_from_nonlinear(struct page *page, |
| 194 | struct address_space *mapping, void *arg) |
| 195 | { |
| 196 | struct vm_area_struct *vma; |
| 197 | /* hugetlbfs does not support remap_pages, so no huge pgoff worries */ |
| 198 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
| 199 | unsigned long addr; |
| 200 | |
| 201 | list_for_each_entry(vma, |
| 202 | &mapping->i_mmap_nonlinear, shared.nonlinear) { |
| 203 | |
| 204 | addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); |
| 205 | if (addr >= vma->vm_start && addr < vma->vm_end) |
| 206 | remove_migration_pte(page, vma, addr, arg); |
| 207 | } |
| 208 | return SWAP_AGAIN; |
| 209 | } |
| 210 | |
| 211 | /* |
| 212 | * Get rid of all migration entries and replace them by |
| 213 | * references to the indicated page. |
| 214 | */ |
| 215 | static void remove_migration_ptes(struct page *old, struct page *new) |
| 216 | { |
| 217 | struct rmap_walk_control rwc = { |
| 218 | .rmap_one = remove_migration_pte, |
| 219 | .arg = old, |
| 220 | .file_nonlinear = remove_linear_migration_ptes_from_nonlinear, |
| 221 | }; |
| 222 | |
| 223 | rmap_walk(new, &rwc); |
| 224 | } |
| 225 | |
| 226 | /* |
| 227 | * Something used the pte of a page under migration. We need to |
| 228 | * get to the page and wait until migration is finished. |
| 229 | * When we return from this function the fault will be retried. |
| 230 | */ |
| 231 | static void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep, |
| 232 | spinlock_t *ptl) |
| 233 | { |
| 234 | pte_t pte; |
| 235 | swp_entry_t entry; |
| 236 | struct page *page; |
| 237 | |
| 238 | spin_lock(ptl); |
| 239 | pte = *ptep; |
| 240 | if (!is_swap_pte(pte)) |
| 241 | goto out; |
| 242 | |
| 243 | entry = pte_to_swp_entry(pte); |
| 244 | if (!is_migration_entry(entry)) |
| 245 | goto out; |
| 246 | |
| 247 | page = migration_entry_to_page(entry); |
| 248 | |
| 249 | /* |
| 250 | * Once radix-tree replacement of page migration started, page_count |
| 251 | * *must* be zero. And, we don't want to call wait_on_page_locked() |
| 252 | * against a page without get_page(). |
| 253 | * So, we use get_page_unless_zero(), here. Even failed, page fault |
| 254 | * will occur again. |
| 255 | */ |
| 256 | if (!get_page_unless_zero(page)) |
| 257 | goto out; |
| 258 | pte_unmap_unlock(ptep, ptl); |
| 259 | wait_on_page_locked(page); |
| 260 | put_page(page); |
| 261 | return; |
| 262 | out: |
| 263 | pte_unmap_unlock(ptep, ptl); |
| 264 | } |
| 265 | |
| 266 | void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, |
| 267 | unsigned long address) |
| 268 | { |
| 269 | spinlock_t *ptl = pte_lockptr(mm, pmd); |
| 270 | pte_t *ptep = pte_offset_map(pmd, address); |
| 271 | __migration_entry_wait(mm, ptep, ptl); |
| 272 | } |
| 273 | |
| 274 | void migration_entry_wait_huge(struct vm_area_struct *vma, |
| 275 | struct mm_struct *mm, pte_t *pte) |
| 276 | { |
| 277 | spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), mm, pte); |
| 278 | __migration_entry_wait(mm, pte, ptl); |
| 279 | } |
| 280 | |
| 281 | #ifdef CONFIG_BLOCK |
| 282 | /* Returns true if all buffers are successfully locked */ |
| 283 | static bool buffer_migrate_lock_buffers(struct buffer_head *head, |
| 284 | enum migrate_mode mode) |
| 285 | { |
| 286 | struct buffer_head *bh = head; |
| 287 | |
| 288 | /* Simple case, sync compaction */ |
| 289 | if (mode != MIGRATE_ASYNC) { |
| 290 | do { |
| 291 | get_bh(bh); |
| 292 | lock_buffer(bh); |
| 293 | bh = bh->b_this_page; |
| 294 | |
| 295 | } while (bh != head); |
| 296 | |
| 297 | return true; |
| 298 | } |
| 299 | |
| 300 | /* async case, we cannot block on lock_buffer so use trylock_buffer */ |
| 301 | do { |
| 302 | get_bh(bh); |
| 303 | if (!trylock_buffer(bh)) { |
| 304 | /* |
| 305 | * We failed to lock the buffer and cannot stall in |
| 306 | * async migration. Release the taken locks |
| 307 | */ |
| 308 | struct buffer_head *failed_bh = bh; |
| 309 | put_bh(failed_bh); |
| 310 | bh = head; |
| 311 | while (bh != failed_bh) { |
| 312 | unlock_buffer(bh); |
| 313 | put_bh(bh); |
| 314 | bh = bh->b_this_page; |
| 315 | } |
| 316 | return false; |
| 317 | } |
| 318 | |
| 319 | bh = bh->b_this_page; |
| 320 | } while (bh != head); |
| 321 | return true; |
| 322 | } |
| 323 | #else |
| 324 | static inline bool buffer_migrate_lock_buffers(struct buffer_head *head, |
| 325 | enum migrate_mode mode) |
| 326 | { |
| 327 | return true; |
| 328 | } |
| 329 | #endif /* CONFIG_BLOCK */ |
| 330 | |
| 331 | /* |
| 332 | * Replace the page in the mapping. |
| 333 | * |
| 334 | * The number of remaining references must be: |
| 335 | * 1 for anonymous pages without a mapping |
| 336 | * 2 for pages with a mapping |
| 337 | * 3 for pages with a mapping and PagePrivate/PagePrivate2 set. |
| 338 | */ |
| 339 | int migrate_page_move_mapping(struct address_space *mapping, |
| 340 | struct page *newpage, struct page *page, |
| 341 | struct buffer_head *head, enum migrate_mode mode, |
| 342 | int extra_count) |
| 343 | { |
| 344 | int expected_count = 1 + extra_count; |
| 345 | void **pslot; |
| 346 | |
| 347 | if (!mapping) { |
| 348 | /* Anonymous page without mapping */ |
| 349 | if (page_count(page) != expected_count) |
| 350 | return -EAGAIN; |
| 351 | return MIGRATEPAGE_SUCCESS; |
| 352 | } |
| 353 | |
| 354 | spin_lock_irq(&mapping->tree_lock); |
| 355 | |
| 356 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
| 357 | page_index(page)); |
| 358 | |
| 359 | expected_count += 1 + page_has_private(page); |
| 360 | if (page_count(page) != expected_count || |
| 361 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { |
| 362 | spin_unlock_irq(&mapping->tree_lock); |
| 363 | return -EAGAIN; |
| 364 | } |
| 365 | |
| 366 | if (!page_freeze_refs(page, expected_count)) { |
| 367 | spin_unlock_irq(&mapping->tree_lock); |
| 368 | return -EAGAIN; |
| 369 | } |
| 370 | |
| 371 | /* |
| 372 | * In the async migration case of moving a page with buffers, lock the |
| 373 | * buffers using trylock before the mapping is moved. If the mapping |
| 374 | * was moved, we later failed to lock the buffers and could not move |
| 375 | * the mapping back due to an elevated page count, we would have to |
| 376 | * block waiting on other references to be dropped. |
| 377 | */ |
| 378 | if (mode == MIGRATE_ASYNC && head && |
| 379 | !buffer_migrate_lock_buffers(head, mode)) { |
| 380 | page_unfreeze_refs(page, expected_count); |
| 381 | spin_unlock_irq(&mapping->tree_lock); |
| 382 | return -EAGAIN; |
| 383 | } |
| 384 | |
| 385 | /* |
| 386 | * Now we know that no one else is looking at the page. |
| 387 | */ |
| 388 | get_page(newpage); /* add cache reference */ |
| 389 | if (PageSwapCache(page)) { |
| 390 | SetPageSwapCache(newpage); |
| 391 | set_page_private(newpage, page_private(page)); |
| 392 | } |
| 393 | |
| 394 | radix_tree_replace_slot(pslot, newpage); |
| 395 | |
| 396 | /* |
| 397 | * Drop cache reference from old page by unfreezing |
| 398 | * to one less reference. |
| 399 | * We know this isn't the last reference. |
| 400 | */ |
| 401 | page_unfreeze_refs(page, expected_count - 1); |
| 402 | |
| 403 | /* |
| 404 | * If moved to a different zone then also account |
| 405 | * the page for that zone. Other VM counters will be |
| 406 | * taken care of when we establish references to the |
| 407 | * new page and drop references to the old page. |
| 408 | * |
| 409 | * Note that anonymous pages are accounted for |
| 410 | * via NR_FILE_PAGES and NR_ANON_PAGES if they |
| 411 | * are mapped to swap space. |
| 412 | */ |
| 413 | __dec_zone_page_state(page, NR_FILE_PAGES); |
| 414 | __inc_zone_page_state(newpage, NR_FILE_PAGES); |
| 415 | if (!PageSwapCache(page) && PageSwapBacked(page)) { |
| 416 | __dec_zone_page_state(page, NR_SHMEM); |
| 417 | __inc_zone_page_state(newpage, NR_SHMEM); |
| 418 | } |
| 419 | spin_unlock_irq(&mapping->tree_lock); |
| 420 | |
| 421 | return MIGRATEPAGE_SUCCESS; |
| 422 | } |
| 423 | |
| 424 | /* |
| 425 | * The expected number of remaining references is the same as that |
| 426 | * of migrate_page_move_mapping(). |
| 427 | */ |
| 428 | int migrate_huge_page_move_mapping(struct address_space *mapping, |
| 429 | struct page *newpage, struct page *page) |
| 430 | { |
| 431 | int expected_count; |
| 432 | void **pslot; |
| 433 | |
| 434 | if (!mapping) { |
| 435 | if (page_count(page) != 1) |
| 436 | return -EAGAIN; |
| 437 | return MIGRATEPAGE_SUCCESS; |
| 438 | } |
| 439 | |
| 440 | spin_lock_irq(&mapping->tree_lock); |
| 441 | |
| 442 | pslot = radix_tree_lookup_slot(&mapping->page_tree, |
| 443 | page_index(page)); |
| 444 | |
| 445 | expected_count = 2 + page_has_private(page); |
| 446 | if (page_count(page) != expected_count || |
| 447 | radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { |
| 448 | spin_unlock_irq(&mapping->tree_lock); |
| 449 | return -EAGAIN; |
| 450 | } |
| 451 | |
| 452 | if (!page_freeze_refs(page, expected_count)) { |
| 453 | spin_unlock_irq(&mapping->tree_lock); |
| 454 | return -EAGAIN; |
| 455 | } |
| 456 | |
| 457 | get_page(newpage); |
| 458 | |
| 459 | radix_tree_replace_slot(pslot, newpage); |
| 460 | |
| 461 | page_unfreeze_refs(page, expected_count - 1); |
| 462 | |
| 463 | spin_unlock_irq(&mapping->tree_lock); |
| 464 | return MIGRATEPAGE_SUCCESS; |
| 465 | } |
| 466 | |
| 467 | /* |
| 468 | * Gigantic pages are so large that we do not guarantee that page++ pointer |
| 469 | * arithmetic will work across the entire page. We need something more |
| 470 | * specialized. |
| 471 | */ |
| 472 | static void __copy_gigantic_page(struct page *dst, struct page *src, |
| 473 | int nr_pages) |
| 474 | { |
| 475 | int i; |
| 476 | struct page *dst_base = dst; |
| 477 | struct page *src_base = src; |
| 478 | |
| 479 | for (i = 0; i < nr_pages; ) { |
| 480 | cond_resched(); |
| 481 | copy_highpage(dst, src); |
| 482 | |
| 483 | i++; |
| 484 | dst = mem_map_next(dst, dst_base, i); |
| 485 | src = mem_map_next(src, src_base, i); |
| 486 | } |
| 487 | } |
| 488 | |
| 489 | static void copy_huge_page(struct page *dst, struct page *src) |
| 490 | { |
| 491 | int i; |
| 492 | int nr_pages; |
| 493 | |
| 494 | if (PageHuge(src)) { |
| 495 | /* hugetlbfs page */ |
| 496 | struct hstate *h = page_hstate(src); |
| 497 | nr_pages = pages_per_huge_page(h); |
| 498 | |
| 499 | if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) { |
| 500 | __copy_gigantic_page(dst, src, nr_pages); |
| 501 | return; |
| 502 | } |
| 503 | } else { |
| 504 | /* thp page */ |
| 505 | BUG_ON(!PageTransHuge(src)); |
| 506 | nr_pages = hpage_nr_pages(src); |
| 507 | } |
| 508 | |
| 509 | for (i = 0; i < nr_pages; i++) { |
| 510 | cond_resched(); |
| 511 | copy_highpage(dst + i, src + i); |
| 512 | } |
| 513 | } |
| 514 | |
| 515 | /* |
| 516 | * Copy the page to its new location |
| 517 | */ |
| 518 | void migrate_page_copy(struct page *newpage, struct page *page) |
| 519 | { |
| 520 | int cpupid; |
| 521 | |
| 522 | if (PageHuge(page) || PageTransHuge(page)) |
| 523 | copy_huge_page(newpage, page); |
| 524 | else |
| 525 | copy_highpage(newpage, page); |
| 526 | |
| 527 | if (PageError(page)) |
| 528 | SetPageError(newpage); |
| 529 | if (PageReferenced(page)) |
| 530 | SetPageReferenced(newpage); |
| 531 | if (PageUptodate(page)) |
| 532 | SetPageUptodate(newpage); |
| 533 | if (TestClearPageActive(page)) { |
| 534 | VM_BUG_ON_PAGE(PageUnevictable(page), page); |
| 535 | SetPageActive(newpage); |
| 536 | } else if (TestClearPageUnevictable(page)) |
| 537 | SetPageUnevictable(newpage); |
| 538 | if (PageChecked(page)) |
| 539 | SetPageChecked(newpage); |
| 540 | if (PageMappedToDisk(page)) |
| 541 | SetPageMappedToDisk(newpage); |
| 542 | |
| 543 | if (PageDirty(page)) { |
| 544 | clear_page_dirty_for_io(page); |
| 545 | /* |
| 546 | * Want to mark the page and the radix tree as dirty, and |
| 547 | * redo the accounting that clear_page_dirty_for_io undid, |
| 548 | * but we can't use set_page_dirty because that function |
| 549 | * is actually a signal that all of the page has become dirty. |
| 550 | * Whereas only part of our page may be dirty. |
| 551 | */ |
| 552 | if (PageSwapBacked(page)) |
| 553 | SetPageDirty(newpage); |
| 554 | else |
| 555 | __set_page_dirty_nobuffers(newpage); |
| 556 | } |
| 557 | |
| 558 | /* |
| 559 | * Copy NUMA information to the new page, to prevent over-eager |
| 560 | * future migrations of this same page. |
| 561 | */ |
| 562 | cpupid = page_cpupid_xchg_last(page, -1); |
| 563 | page_cpupid_xchg_last(newpage, cpupid); |
| 564 | |
| 565 | mlock_migrate_page(newpage, page); |
| 566 | ksm_migrate_page(newpage, page); |
| 567 | /* |
| 568 | * Please do not reorder this without considering how mm/ksm.c's |
| 569 | * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache(). |
| 570 | */ |
| 571 | ClearPageSwapCache(page); |
| 572 | ClearPagePrivate(page); |
| 573 | set_page_private(page, 0); |
| 574 | |
| 575 | /* |
| 576 | * If any waiters have accumulated on the new page then |
| 577 | * wake them up. |
| 578 | */ |
| 579 | if (PageWriteback(newpage)) |
| 580 | end_page_writeback(newpage); |
| 581 | } |
| 582 | |
| 583 | /************************************************************ |
| 584 | * Migration functions |
| 585 | ***********************************************************/ |
| 586 | |
| 587 | /* |
| 588 | * Common logic to directly migrate a single page suitable for |
| 589 | * pages that do not use PagePrivate/PagePrivate2. |
| 590 | * |
| 591 | * Pages are locked upon entry and exit. |
| 592 | */ |
| 593 | int migrate_page(struct address_space *mapping, |
| 594 | struct page *newpage, struct page *page, |
| 595 | enum migrate_mode mode) |
| 596 | { |
| 597 | int rc; |
| 598 | |
| 599 | BUG_ON(PageWriteback(page)); /* Writeback must be complete */ |
| 600 | |
| 601 | rc = migrate_page_move_mapping(mapping, newpage, page, NULL, mode, 0); |
| 602 | |
| 603 | if (rc != MIGRATEPAGE_SUCCESS) |
| 604 | return rc; |
| 605 | |
| 606 | migrate_page_copy(newpage, page); |
| 607 | return MIGRATEPAGE_SUCCESS; |
| 608 | } |
| 609 | EXPORT_SYMBOL(migrate_page); |
| 610 | |
| 611 | #ifdef CONFIG_BLOCK |
| 612 | /* |
| 613 | * Migration function for pages with buffers. This function can only be used |
| 614 | * if the underlying filesystem guarantees that no other references to "page" |
| 615 | * exist. |
| 616 | */ |
| 617 | int buffer_migrate_page(struct address_space *mapping, |
| 618 | struct page *newpage, struct page *page, enum migrate_mode mode) |
| 619 | { |
| 620 | struct buffer_head *bh, *head; |
| 621 | int rc; |
| 622 | |
| 623 | if (!page_has_buffers(page)) |
| 624 | return migrate_page(mapping, newpage, page, mode); |
| 625 | |
| 626 | head = page_buffers(page); |
| 627 | |
| 628 | rc = migrate_page_move_mapping(mapping, newpage, page, head, mode, 0); |
| 629 | |
| 630 | if (rc != MIGRATEPAGE_SUCCESS) |
| 631 | return rc; |
| 632 | |
| 633 | /* |
| 634 | * In the async case, migrate_page_move_mapping locked the buffers |
| 635 | * with an IRQ-safe spinlock held. In the sync case, the buffers |
| 636 | * need to be locked now |
| 637 | */ |
| 638 | if (mode != MIGRATE_ASYNC) |
| 639 | BUG_ON(!buffer_migrate_lock_buffers(head, mode)); |
| 640 | |
| 641 | ClearPagePrivate(page); |
| 642 | set_page_private(newpage, page_private(page)); |
| 643 | set_page_private(page, 0); |
| 644 | put_page(page); |
| 645 | get_page(newpage); |
| 646 | |
| 647 | bh = head; |
| 648 | do { |
| 649 | set_bh_page(bh, newpage, bh_offset(bh)); |
| 650 | bh = bh->b_this_page; |
| 651 | |
| 652 | } while (bh != head); |
| 653 | |
| 654 | SetPagePrivate(newpage); |
| 655 | |
| 656 | migrate_page_copy(newpage, page); |
| 657 | |
| 658 | bh = head; |
| 659 | do { |
| 660 | unlock_buffer(bh); |
| 661 | put_bh(bh); |
| 662 | bh = bh->b_this_page; |
| 663 | |
| 664 | } while (bh != head); |
| 665 | |
| 666 | return MIGRATEPAGE_SUCCESS; |
| 667 | } |
| 668 | EXPORT_SYMBOL(buffer_migrate_page); |
| 669 | #endif |
| 670 | |
| 671 | /* |
| 672 | * Writeback a page to clean the dirty state |
| 673 | */ |
| 674 | static int writeout(struct address_space *mapping, struct page *page) |
| 675 | { |
| 676 | struct writeback_control wbc = { |
| 677 | .sync_mode = WB_SYNC_NONE, |
| 678 | .nr_to_write = 1, |
| 679 | .range_start = 0, |
| 680 | .range_end = LLONG_MAX, |
| 681 | .for_reclaim = 1 |
| 682 | }; |
| 683 | int rc; |
| 684 | |
| 685 | if (!mapping->a_ops->writepage) |
| 686 | /* No write method for the address space */ |
| 687 | return -EINVAL; |
| 688 | |
| 689 | if (!clear_page_dirty_for_io(page)) |
| 690 | /* Someone else already triggered a write */ |
| 691 | return -EAGAIN; |
| 692 | |
| 693 | /* |
| 694 | * A dirty page may imply that the underlying filesystem has |
| 695 | * the page on some queue. So the page must be clean for |
| 696 | * migration. Writeout may mean we loose the lock and the |
| 697 | * page state is no longer what we checked for earlier. |
| 698 | * At this point we know that the migration attempt cannot |
| 699 | * be successful. |
| 700 | */ |
| 701 | remove_migration_ptes(page, page); |
| 702 | |
| 703 | rc = mapping->a_ops->writepage(page, &wbc); |
| 704 | |
| 705 | if (rc != AOP_WRITEPAGE_ACTIVATE) |
| 706 | /* unlocked. Relock */ |
| 707 | lock_page(page); |
| 708 | |
| 709 | return (rc < 0) ? -EIO : -EAGAIN; |
| 710 | } |
| 711 | |
| 712 | /* |
| 713 | * Default handling if a filesystem does not provide a migration function. |
| 714 | */ |
| 715 | static int fallback_migrate_page(struct address_space *mapping, |
| 716 | struct page *newpage, struct page *page, enum migrate_mode mode) |
| 717 | { |
| 718 | if (PageDirty(page)) { |
| 719 | /* Only writeback pages in full synchronous migration */ |
| 720 | if (mode != MIGRATE_SYNC) |
| 721 | return -EBUSY; |
| 722 | return writeout(mapping, page); |
| 723 | } |
| 724 | |
| 725 | /* |
| 726 | * Buffers may be managed in a filesystem specific way. |
| 727 | * We must have no buffers or drop them. |
| 728 | */ |
| 729 | if (page_has_private(page) && |
| 730 | !try_to_release_page(page, GFP_KERNEL)) |
| 731 | return -EAGAIN; |
| 732 | |
| 733 | return migrate_page(mapping, newpage, page, mode); |
| 734 | } |
| 735 | |
| 736 | /* |
| 737 | * Move a page to a newly allocated page |
| 738 | * The page is locked and all ptes have been successfully removed. |
| 739 | * |
| 740 | * The new page will have replaced the old page if this function |
| 741 | * is successful. |
| 742 | * |
| 743 | * Return value: |
| 744 | * < 0 - error code |
| 745 | * MIGRATEPAGE_SUCCESS - success |
| 746 | */ |
| 747 | static int move_to_new_page(struct page *newpage, struct page *page, |
| 748 | int remap_swapcache, enum migrate_mode mode) |
| 749 | { |
| 750 | struct address_space *mapping; |
| 751 | int rc; |
| 752 | |
| 753 | /* |
| 754 | * Block others from accessing the page when we get around to |
| 755 | * establishing additional references. We are the only one |
| 756 | * holding a reference to the new page at this point. |
| 757 | */ |
| 758 | if (!trylock_page(newpage)) |
| 759 | BUG(); |
| 760 | |
| 761 | /* Prepare mapping for the new page.*/ |
| 762 | newpage->index = page->index; |
| 763 | newpage->mapping = page->mapping; |
| 764 | if (PageSwapBacked(page)) |
| 765 | SetPageSwapBacked(newpage); |
| 766 | |
| 767 | mapping = page_mapping(page); |
| 768 | if (!mapping) |
| 769 | rc = migrate_page(mapping, newpage, page, mode); |
| 770 | else if (mapping->a_ops->migratepage) |
| 771 | /* |
| 772 | * Most pages have a mapping and most filesystems provide a |
| 773 | * migratepage callback. Anonymous pages are part of swap |
| 774 | * space which also has its own migratepage callback. This |
| 775 | * is the most common path for page migration. |
| 776 | */ |
| 777 | rc = mapping->a_ops->migratepage(mapping, |
| 778 | newpage, page, mode); |
| 779 | else |
| 780 | rc = fallback_migrate_page(mapping, newpage, page, mode); |
| 781 | |
| 782 | if (rc != MIGRATEPAGE_SUCCESS) { |
| 783 | newpage->mapping = NULL; |
| 784 | } else { |
| 785 | if (remap_swapcache) |
| 786 | remove_migration_ptes(page, newpage); |
| 787 | page->mapping = NULL; |
| 788 | } |
| 789 | |
| 790 | unlock_page(newpage); |
| 791 | |
| 792 | return rc; |
| 793 | } |
| 794 | |
| 795 | static int __unmap_and_move(struct page *page, struct page *newpage, |
| 796 | int force, enum migrate_mode mode) |
| 797 | { |
| 798 | int rc = -EAGAIN; |
| 799 | int remap_swapcache = 1; |
| 800 | struct mem_cgroup *mem; |
| 801 | struct anon_vma *anon_vma = NULL; |
| 802 | |
| 803 | if (!trylock_page(page)) { |
| 804 | if (!force || mode == MIGRATE_ASYNC) |
| 805 | goto out; |
| 806 | |
| 807 | /* |
| 808 | * It's not safe for direct compaction to call lock_page. |
| 809 | * For example, during page readahead pages are added locked |
| 810 | * to the LRU. Later, when the IO completes the pages are |
| 811 | * marked uptodate and unlocked. However, the queueing |
| 812 | * could be merging multiple pages for one bio (e.g. |
| 813 | * mpage_readpages). If an allocation happens for the |
| 814 | * second or third page, the process can end up locking |
| 815 | * the same page twice and deadlocking. Rather than |
| 816 | * trying to be clever about what pages can be locked, |
| 817 | * avoid the use of lock_page for direct compaction |
| 818 | * altogether. |
| 819 | */ |
| 820 | if (current->flags & PF_MEMALLOC) |
| 821 | goto out; |
| 822 | |
| 823 | lock_page(page); |
| 824 | } |
| 825 | |
| 826 | /* charge against new page */ |
| 827 | mem_cgroup_prepare_migration(page, newpage, &mem); |
| 828 | |
| 829 | if (PageWriteback(page)) { |
| 830 | /* |
| 831 | * Only in the case of a full synchronous migration is it |
| 832 | * necessary to wait for PageWriteback. In the async case, |
| 833 | * the retry loop is too short and in the sync-light case, |
| 834 | * the overhead of stalling is too much |
| 835 | */ |
| 836 | if (mode != MIGRATE_SYNC) { |
| 837 | rc = -EBUSY; |
| 838 | goto uncharge; |
| 839 | } |
| 840 | if (!force) |
| 841 | goto uncharge; |
| 842 | wait_on_page_writeback(page); |
| 843 | } |
| 844 | /* |
| 845 | * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, |
| 846 | * we cannot notice that anon_vma is freed while we migrates a page. |
| 847 | * This get_anon_vma() delays freeing anon_vma pointer until the end |
| 848 | * of migration. File cache pages are no problem because of page_lock() |
| 849 | * File Caches may use write_page() or lock_page() in migration, then, |
| 850 | * just care Anon page here. |
| 851 | */ |
| 852 | if (PageAnon(page) && !PageKsm(page)) { |
| 853 | /* |
| 854 | * Only page_lock_anon_vma_read() understands the subtleties of |
| 855 | * getting a hold on an anon_vma from outside one of its mms. |
| 856 | */ |
| 857 | anon_vma = page_get_anon_vma(page); |
| 858 | if (anon_vma) { |
| 859 | /* |
| 860 | * Anon page |
| 861 | */ |
| 862 | } else if (PageSwapCache(page)) { |
| 863 | /* |
| 864 | * We cannot be sure that the anon_vma of an unmapped |
| 865 | * swapcache page is safe to use because we don't |
| 866 | * know in advance if the VMA that this page belonged |
| 867 | * to still exists. If the VMA and others sharing the |
| 868 | * data have been freed, then the anon_vma could |
| 869 | * already be invalid. |
| 870 | * |
| 871 | * To avoid this possibility, swapcache pages get |
| 872 | * migrated but are not remapped when migration |
| 873 | * completes |
| 874 | */ |
| 875 | remap_swapcache = 0; |
| 876 | } else { |
| 877 | goto uncharge; |
| 878 | } |
| 879 | } |
| 880 | |
| 881 | if (unlikely(balloon_page_movable(page))) { |
| 882 | /* |
| 883 | * A ballooned page does not need any special attention from |
| 884 | * physical to virtual reverse mapping procedures. |
| 885 | * Skip any attempt to unmap PTEs or to remap swap cache, |
| 886 | * in order to avoid burning cycles at rmap level, and perform |
| 887 | * the page migration right away (proteced by page lock). |
| 888 | */ |
| 889 | rc = balloon_page_migrate(newpage, page, mode); |
| 890 | goto uncharge; |
| 891 | } |
| 892 | |
| 893 | /* |
| 894 | * Corner case handling: |
| 895 | * 1. When a new swap-cache page is read into, it is added to the LRU |
| 896 | * and treated as swapcache but it has no rmap yet. |
| 897 | * Calling try_to_unmap() against a page->mapping==NULL page will |
| 898 | * trigger a BUG. So handle it here. |
| 899 | * 2. An orphaned page (see truncate_complete_page) might have |
| 900 | * fs-private metadata. The page can be picked up due to memory |
| 901 | * offlining. Everywhere else except page reclaim, the page is |
| 902 | * invisible to the vm, so the page can not be migrated. So try to |
| 903 | * free the metadata, so the page can be freed. |
| 904 | */ |
| 905 | if (!page->mapping) { |
| 906 | VM_BUG_ON_PAGE(PageAnon(page), page); |
| 907 | if (page_has_private(page)) { |
| 908 | try_to_free_buffers(page); |
| 909 | goto uncharge; |
| 910 | } |
| 911 | goto skip_unmap; |
| 912 | } |
| 913 | |
| 914 | /* Establish migration ptes or remove ptes */ |
| 915 | try_to_unmap(page, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); |
| 916 | |
| 917 | skip_unmap: |
| 918 | if (!page_mapped(page)) |
| 919 | rc = move_to_new_page(newpage, page, remap_swapcache, mode); |
| 920 | |
| 921 | if (rc && remap_swapcache) |
| 922 | remove_migration_ptes(page, page); |
| 923 | |
| 924 | /* Drop an anon_vma reference if we took one */ |
| 925 | if (anon_vma) |
| 926 | put_anon_vma(anon_vma); |
| 927 | |
| 928 | uncharge: |
| 929 | mem_cgroup_end_migration(mem, page, newpage, |
| 930 | (rc == MIGRATEPAGE_SUCCESS || |
| 931 | rc == MIGRATEPAGE_BALLOON_SUCCESS)); |
| 932 | unlock_page(page); |
| 933 | out: |
| 934 | return rc; |
| 935 | } |
| 936 | |
| 937 | /* |
| 938 | * Obtain the lock on page, remove all ptes and migrate the page |
| 939 | * to the newly allocated page in newpage. |
| 940 | */ |
| 941 | static int unmap_and_move(new_page_t get_new_page, unsigned long private, |
| 942 | struct page *page, int force, enum migrate_mode mode) |
| 943 | { |
| 944 | int rc = 0; |
| 945 | int *result = NULL; |
| 946 | struct page *newpage = get_new_page(page, private, &result); |
| 947 | |
| 948 | if (!newpage) |
| 949 | return -ENOMEM; |
| 950 | |
| 951 | if (page_count(page) == 1) { |
| 952 | /* page was freed from under us. So we are done. */ |
| 953 | goto out; |
| 954 | } |
| 955 | |
| 956 | if (unlikely(PageTransHuge(page))) |
| 957 | if (unlikely(split_huge_page(page))) |
| 958 | goto out; |
| 959 | |
| 960 | rc = __unmap_and_move(page, newpage, force, mode); |
| 961 | |
| 962 | if (unlikely(rc == MIGRATEPAGE_BALLOON_SUCCESS)) { |
| 963 | /* |
| 964 | * A ballooned page has been migrated already. |
| 965 | * Now, it's the time to wrap-up counters, |
| 966 | * handle the page back to Buddy and return. |
| 967 | */ |
| 968 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
| 969 | page_is_file_cache(page)); |
| 970 | balloon_page_free(page); |
| 971 | return MIGRATEPAGE_SUCCESS; |
| 972 | } |
| 973 | out: |
| 974 | if (rc != -EAGAIN) { |
| 975 | /* |
| 976 | * A page that has been migrated has all references |
| 977 | * removed and will be freed. A page that has not been |
| 978 | * migrated will have kepts its references and be |
| 979 | * restored. |
| 980 | */ |
| 981 | list_del(&page->lru); |
| 982 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
| 983 | page_is_file_cache(page)); |
| 984 | putback_lru_page(page); |
| 985 | } |
| 986 | /* |
| 987 | * Move the new page to the LRU. If migration was not successful |
| 988 | * then this will free the page. |
| 989 | */ |
| 990 | putback_lru_page(newpage); |
| 991 | if (result) { |
| 992 | if (rc) |
| 993 | *result = rc; |
| 994 | else |
| 995 | *result = page_to_nid(newpage); |
| 996 | } |
| 997 | return rc; |
| 998 | } |
| 999 | |
| 1000 | /* |
| 1001 | * Counterpart of unmap_and_move_page() for hugepage migration. |
| 1002 | * |
| 1003 | * This function doesn't wait the completion of hugepage I/O |
| 1004 | * because there is no race between I/O and migration for hugepage. |
| 1005 | * Note that currently hugepage I/O occurs only in direct I/O |
| 1006 | * where no lock is held and PG_writeback is irrelevant, |
| 1007 | * and writeback status of all subpages are counted in the reference |
| 1008 | * count of the head page (i.e. if all subpages of a 2MB hugepage are |
| 1009 | * under direct I/O, the reference of the head page is 512 and a bit more.) |
| 1010 | * This means that when we try to migrate hugepage whose subpages are |
| 1011 | * doing direct I/O, some references remain after try_to_unmap() and |
| 1012 | * hugepage migration fails without data corruption. |
| 1013 | * |
| 1014 | * There is also no race when direct I/O is issued on the page under migration, |
| 1015 | * because then pte is replaced with migration swap entry and direct I/O code |
| 1016 | * will wait in the page fault for migration to complete. |
| 1017 | */ |
| 1018 | static int unmap_and_move_huge_page(new_page_t get_new_page, |
| 1019 | unsigned long private, struct page *hpage, |
| 1020 | int force, enum migrate_mode mode) |
| 1021 | { |
| 1022 | int rc = 0; |
| 1023 | int *result = NULL; |
| 1024 | struct page *new_hpage; |
| 1025 | struct anon_vma *anon_vma = NULL; |
| 1026 | |
| 1027 | /* |
| 1028 | * Movability of hugepages depends on architectures and hugepage size. |
| 1029 | * This check is necessary because some callers of hugepage migration |
| 1030 | * like soft offline and memory hotremove don't walk through page |
| 1031 | * tables or check whether the hugepage is pmd-based or not before |
| 1032 | * kicking migration. |
| 1033 | */ |
| 1034 | if (!hugepage_migration_support(page_hstate(hpage))) { |
| 1035 | putback_active_hugepage(hpage); |
| 1036 | return -ENOSYS; |
| 1037 | } |
| 1038 | |
| 1039 | new_hpage = get_new_page(hpage, private, &result); |
| 1040 | if (!new_hpage) |
| 1041 | return -ENOMEM; |
| 1042 | |
| 1043 | rc = -EAGAIN; |
| 1044 | |
| 1045 | if (!trylock_page(hpage)) { |
| 1046 | if (!force || mode != MIGRATE_SYNC) |
| 1047 | goto out; |
| 1048 | lock_page(hpage); |
| 1049 | } |
| 1050 | |
| 1051 | if (PageAnon(hpage)) |
| 1052 | anon_vma = page_get_anon_vma(hpage); |
| 1053 | |
| 1054 | try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS); |
| 1055 | |
| 1056 | if (!page_mapped(hpage)) |
| 1057 | rc = move_to_new_page(new_hpage, hpage, 1, mode); |
| 1058 | |
| 1059 | if (rc) |
| 1060 | remove_migration_ptes(hpage, hpage); |
| 1061 | |
| 1062 | if (anon_vma) |
| 1063 | put_anon_vma(anon_vma); |
| 1064 | |
| 1065 | if (!rc) |
| 1066 | hugetlb_cgroup_migrate(hpage, new_hpage); |
| 1067 | |
| 1068 | unlock_page(hpage); |
| 1069 | out: |
| 1070 | if (rc != -EAGAIN) |
| 1071 | putback_active_hugepage(hpage); |
| 1072 | put_page(new_hpage); |
| 1073 | if (result) { |
| 1074 | if (rc) |
| 1075 | *result = rc; |
| 1076 | else |
| 1077 | *result = page_to_nid(new_hpage); |
| 1078 | } |
| 1079 | return rc; |
| 1080 | } |
| 1081 | |
| 1082 | /* |
| 1083 | * migrate_pages - migrate the pages specified in a list, to the free pages |
| 1084 | * supplied as the target for the page migration |
| 1085 | * |
| 1086 | * @from: The list of pages to be migrated. |
| 1087 | * @get_new_page: The function used to allocate free pages to be used |
| 1088 | * as the target of the page migration. |
| 1089 | * @private: Private data to be passed on to get_new_page() |
| 1090 | * @mode: The migration mode that specifies the constraints for |
| 1091 | * page migration, if any. |
| 1092 | * @reason: The reason for page migration. |
| 1093 | * |
| 1094 | * The function returns after 10 attempts or if no pages are movable any more |
| 1095 | * because the list has become empty or no retryable pages exist any more. |
| 1096 | * The caller should call putback_lru_pages() to return pages to the LRU |
| 1097 | * or free list only if ret != 0. |
| 1098 | * |
| 1099 | * Returns the number of pages that were not migrated, or an error code. |
| 1100 | */ |
| 1101 | int migrate_pages(struct list_head *from, new_page_t get_new_page, |
| 1102 | unsigned long private, enum migrate_mode mode, int reason) |
| 1103 | { |
| 1104 | int retry = 1; |
| 1105 | int nr_failed = 0; |
| 1106 | int nr_succeeded = 0; |
| 1107 | int pass = 0; |
| 1108 | struct page *page; |
| 1109 | struct page *page2; |
| 1110 | int swapwrite = current->flags & PF_SWAPWRITE; |
| 1111 | int rc; |
| 1112 | |
| 1113 | if (!swapwrite) |
| 1114 | current->flags |= PF_SWAPWRITE; |
| 1115 | |
| 1116 | for(pass = 0; pass < 10 && retry; pass++) { |
| 1117 | retry = 0; |
| 1118 | |
| 1119 | list_for_each_entry_safe(page, page2, from, lru) { |
| 1120 | cond_resched(); |
| 1121 | |
| 1122 | if (PageHuge(page)) |
| 1123 | rc = unmap_and_move_huge_page(get_new_page, |
| 1124 | private, page, pass > 2, mode); |
| 1125 | else |
| 1126 | rc = unmap_and_move(get_new_page, private, |
| 1127 | page, pass > 2, mode); |
| 1128 | |
| 1129 | switch(rc) { |
| 1130 | case -ENOMEM: |
| 1131 | goto out; |
| 1132 | case -EAGAIN: |
| 1133 | retry++; |
| 1134 | break; |
| 1135 | case MIGRATEPAGE_SUCCESS: |
| 1136 | nr_succeeded++; |
| 1137 | break; |
| 1138 | default: |
| 1139 | /* |
| 1140 | * Permanent failure (-EBUSY, -ENOSYS, etc.): |
| 1141 | * unlike -EAGAIN case, the failed page is |
| 1142 | * removed from migration page list and not |
| 1143 | * retried in the next outer loop. |
| 1144 | */ |
| 1145 | nr_failed++; |
| 1146 | break; |
| 1147 | } |
| 1148 | } |
| 1149 | } |
| 1150 | rc = nr_failed + retry; |
| 1151 | out: |
| 1152 | if (nr_succeeded) |
| 1153 | count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); |
| 1154 | if (nr_failed) |
| 1155 | count_vm_events(PGMIGRATE_FAIL, nr_failed); |
| 1156 | trace_mm_migrate_pages(nr_succeeded, nr_failed, mode, reason); |
| 1157 | |
| 1158 | if (!swapwrite) |
| 1159 | current->flags &= ~PF_SWAPWRITE; |
| 1160 | |
| 1161 | return rc; |
| 1162 | } |
| 1163 | |
| 1164 | #ifdef CONFIG_NUMA |
| 1165 | /* |
| 1166 | * Move a list of individual pages |
| 1167 | */ |
| 1168 | struct page_to_node { |
| 1169 | unsigned long addr; |
| 1170 | struct page *page; |
| 1171 | int node; |
| 1172 | int status; |
| 1173 | }; |
| 1174 | |
| 1175 | static struct page *new_page_node(struct page *p, unsigned long private, |
| 1176 | int **result) |
| 1177 | { |
| 1178 | struct page_to_node *pm = (struct page_to_node *)private; |
| 1179 | |
| 1180 | while (pm->node != MAX_NUMNODES && pm->page != p) |
| 1181 | pm++; |
| 1182 | |
| 1183 | if (pm->node == MAX_NUMNODES) |
| 1184 | return NULL; |
| 1185 | |
| 1186 | *result = &pm->status; |
| 1187 | |
| 1188 | if (PageHuge(p)) |
| 1189 | return alloc_huge_page_node(page_hstate(compound_head(p)), |
| 1190 | pm->node); |
| 1191 | else |
| 1192 | return alloc_pages_exact_node(pm->node, |
| 1193 | GFP_HIGHUSER_MOVABLE | __GFP_THISNODE, 0); |
| 1194 | } |
| 1195 | |
| 1196 | /* |
| 1197 | * Move a set of pages as indicated in the pm array. The addr |
| 1198 | * field must be set to the virtual address of the page to be moved |
| 1199 | * and the node number must contain a valid target node. |
| 1200 | * The pm array ends with node = MAX_NUMNODES. |
| 1201 | */ |
| 1202 | static int do_move_page_to_node_array(struct mm_struct *mm, |
| 1203 | struct page_to_node *pm, |
| 1204 | int migrate_all) |
| 1205 | { |
| 1206 | int err; |
| 1207 | struct page_to_node *pp; |
| 1208 | LIST_HEAD(pagelist); |
| 1209 | |
| 1210 | down_read(&mm->mmap_sem); |
| 1211 | |
| 1212 | /* |
| 1213 | * Build a list of pages to migrate |
| 1214 | */ |
| 1215 | for (pp = pm; pp->node != MAX_NUMNODES; pp++) { |
| 1216 | struct vm_area_struct *vma; |
| 1217 | struct page *page; |
| 1218 | |
| 1219 | err = -EFAULT; |
| 1220 | vma = find_vma(mm, pp->addr); |
| 1221 | if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma)) |
| 1222 | goto set_status; |
| 1223 | |
| 1224 | page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT); |
| 1225 | |
| 1226 | err = PTR_ERR(page); |
| 1227 | if (IS_ERR(page)) |
| 1228 | goto set_status; |
| 1229 | |
| 1230 | err = -ENOENT; |
| 1231 | if (!page) |
| 1232 | goto set_status; |
| 1233 | |
| 1234 | /* Use PageReserved to check for zero page */ |
| 1235 | if (PageReserved(page)) |
| 1236 | goto put_and_set; |
| 1237 | |
| 1238 | pp->page = page; |
| 1239 | err = page_to_nid(page); |
| 1240 | |
| 1241 | if (err == pp->node) |
| 1242 | /* |
| 1243 | * Node already in the right place |
| 1244 | */ |
| 1245 | goto put_and_set; |
| 1246 | |
| 1247 | err = -EACCES; |
| 1248 | if (page_mapcount(page) > 1 && |
| 1249 | !migrate_all) |
| 1250 | goto put_and_set; |
| 1251 | |
| 1252 | if (PageHuge(page)) { |
| 1253 | isolate_huge_page(page, &pagelist); |
| 1254 | goto put_and_set; |
| 1255 | } |
| 1256 | |
| 1257 | err = isolate_lru_page(page); |
| 1258 | if (!err) { |
| 1259 | list_add_tail(&page->lru, &pagelist); |
| 1260 | inc_zone_page_state(page, NR_ISOLATED_ANON + |
| 1261 | page_is_file_cache(page)); |
| 1262 | } |
| 1263 | put_and_set: |
| 1264 | /* |
| 1265 | * Either remove the duplicate refcount from |
| 1266 | * isolate_lru_page() or drop the page ref if it was |
| 1267 | * not isolated. |
| 1268 | */ |
| 1269 | put_page(page); |
| 1270 | set_status: |
| 1271 | pp->status = err; |
| 1272 | } |
| 1273 | |
| 1274 | err = 0; |
| 1275 | if (!list_empty(&pagelist)) { |
| 1276 | err = migrate_pages(&pagelist, new_page_node, |
| 1277 | (unsigned long)pm, MIGRATE_SYNC, MR_SYSCALL); |
| 1278 | if (err) |
| 1279 | putback_movable_pages(&pagelist); |
| 1280 | } |
| 1281 | |
| 1282 | up_read(&mm->mmap_sem); |
| 1283 | return err; |
| 1284 | } |
| 1285 | |
| 1286 | /* |
| 1287 | * Migrate an array of page address onto an array of nodes and fill |
| 1288 | * the corresponding array of status. |
| 1289 | */ |
| 1290 | static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, |
| 1291 | unsigned long nr_pages, |
| 1292 | const void __user * __user *pages, |
| 1293 | const int __user *nodes, |
| 1294 | int __user *status, int flags) |
| 1295 | { |
| 1296 | struct page_to_node *pm; |
| 1297 | unsigned long chunk_nr_pages; |
| 1298 | unsigned long chunk_start; |
| 1299 | int err; |
| 1300 | |
| 1301 | err = -ENOMEM; |
| 1302 | pm = (struct page_to_node *)__get_free_page(GFP_KERNEL); |
| 1303 | if (!pm) |
| 1304 | goto out; |
| 1305 | |
| 1306 | migrate_prep(); |
| 1307 | |
| 1308 | /* |
| 1309 | * Store a chunk of page_to_node array in a page, |
| 1310 | * but keep the last one as a marker |
| 1311 | */ |
| 1312 | chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1; |
| 1313 | |
| 1314 | for (chunk_start = 0; |
| 1315 | chunk_start < nr_pages; |
| 1316 | chunk_start += chunk_nr_pages) { |
| 1317 | int j; |
| 1318 | |
| 1319 | if (chunk_start + chunk_nr_pages > nr_pages) |
| 1320 | chunk_nr_pages = nr_pages - chunk_start; |
| 1321 | |
| 1322 | /* fill the chunk pm with addrs and nodes from user-space */ |
| 1323 | for (j = 0; j < chunk_nr_pages; j++) { |
| 1324 | const void __user *p; |
| 1325 | int node; |
| 1326 | |
| 1327 | err = -EFAULT; |
| 1328 | if (get_user(p, pages + j + chunk_start)) |
| 1329 | goto out_pm; |
| 1330 | pm[j].addr = (unsigned long) p; |
| 1331 | |
| 1332 | if (get_user(node, nodes + j + chunk_start)) |
| 1333 | goto out_pm; |
| 1334 | |
| 1335 | err = -ENODEV; |
| 1336 | if (node < 0 || node >= MAX_NUMNODES) |
| 1337 | goto out_pm; |
| 1338 | |
| 1339 | if (!node_state(node, N_MEMORY)) |
| 1340 | goto out_pm; |
| 1341 | |
| 1342 | err = -EACCES; |
| 1343 | if (!node_isset(node, task_nodes)) |
| 1344 | goto out_pm; |
| 1345 | |
| 1346 | pm[j].node = node; |
| 1347 | } |
| 1348 | |
| 1349 | /* End marker for this chunk */ |
| 1350 | pm[chunk_nr_pages].node = MAX_NUMNODES; |
| 1351 | |
| 1352 | /* Migrate this chunk */ |
| 1353 | err = do_move_page_to_node_array(mm, pm, |
| 1354 | flags & MPOL_MF_MOVE_ALL); |
| 1355 | if (err < 0) |
| 1356 | goto out_pm; |
| 1357 | |
| 1358 | /* Return status information */ |
| 1359 | for (j = 0; j < chunk_nr_pages; j++) |
| 1360 | if (put_user(pm[j].status, status + j + chunk_start)) { |
| 1361 | err = -EFAULT; |
| 1362 | goto out_pm; |
| 1363 | } |
| 1364 | } |
| 1365 | err = 0; |
| 1366 | |
| 1367 | out_pm: |
| 1368 | free_page((unsigned long)pm); |
| 1369 | out: |
| 1370 | return err; |
| 1371 | } |
| 1372 | |
| 1373 | /* |
| 1374 | * Determine the nodes of an array of pages and store it in an array of status. |
| 1375 | */ |
| 1376 | static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, |
| 1377 | const void __user **pages, int *status) |
| 1378 | { |
| 1379 | unsigned long i; |
| 1380 | |
| 1381 | down_read(&mm->mmap_sem); |
| 1382 | |
| 1383 | for (i = 0; i < nr_pages; i++) { |
| 1384 | unsigned long addr = (unsigned long)(*pages); |
| 1385 | struct vm_area_struct *vma; |
| 1386 | struct page *page; |
| 1387 | int err = -EFAULT; |
| 1388 | |
| 1389 | vma = find_vma(mm, addr); |
| 1390 | if (!vma || addr < vma->vm_start) |
| 1391 | goto set_status; |
| 1392 | |
| 1393 | page = follow_page(vma, addr, 0); |
| 1394 | |
| 1395 | err = PTR_ERR(page); |
| 1396 | if (IS_ERR(page)) |
| 1397 | goto set_status; |
| 1398 | |
| 1399 | err = -ENOENT; |
| 1400 | /* Use PageReserved to check for zero page */ |
| 1401 | if (!page || PageReserved(page)) |
| 1402 | goto set_status; |
| 1403 | |
| 1404 | err = page_to_nid(page); |
| 1405 | set_status: |
| 1406 | *status = err; |
| 1407 | |
| 1408 | pages++; |
| 1409 | status++; |
| 1410 | } |
| 1411 | |
| 1412 | up_read(&mm->mmap_sem); |
| 1413 | } |
| 1414 | |
| 1415 | /* |
| 1416 | * Determine the nodes of a user array of pages and store it in |
| 1417 | * a user array of status. |
| 1418 | */ |
| 1419 | static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, |
| 1420 | const void __user * __user *pages, |
| 1421 | int __user *status) |
| 1422 | { |
| 1423 | #define DO_PAGES_STAT_CHUNK_NR 16 |
| 1424 | const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR]; |
| 1425 | int chunk_status[DO_PAGES_STAT_CHUNK_NR]; |
| 1426 | |
| 1427 | while (nr_pages) { |
| 1428 | unsigned long chunk_nr; |
| 1429 | |
| 1430 | chunk_nr = nr_pages; |
| 1431 | if (chunk_nr > DO_PAGES_STAT_CHUNK_NR) |
| 1432 | chunk_nr = DO_PAGES_STAT_CHUNK_NR; |
| 1433 | |
| 1434 | if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages))) |
| 1435 | break; |
| 1436 | |
| 1437 | do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status); |
| 1438 | |
| 1439 | if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status))) |
| 1440 | break; |
| 1441 | |
| 1442 | pages += chunk_nr; |
| 1443 | status += chunk_nr; |
| 1444 | nr_pages -= chunk_nr; |
| 1445 | } |
| 1446 | return nr_pages ? -EFAULT : 0; |
| 1447 | } |
| 1448 | |
| 1449 | /* |
| 1450 | * Move a list of pages in the address space of the currently executing |
| 1451 | * process. |
| 1452 | */ |
| 1453 | SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, |
| 1454 | const void __user * __user *, pages, |
| 1455 | const int __user *, nodes, |
| 1456 | int __user *, status, int, flags) |
| 1457 | { |
| 1458 | const struct cred *cred = current_cred(), *tcred; |
| 1459 | struct task_struct *task; |
| 1460 | struct mm_struct *mm; |
| 1461 | int err; |
| 1462 | nodemask_t task_nodes; |
| 1463 | |
| 1464 | /* Check flags */ |
| 1465 | if (flags & ~(MPOL_MF_MOVE|MPOL_MF_MOVE_ALL)) |
| 1466 | return -EINVAL; |
| 1467 | |
| 1468 | if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE)) |
| 1469 | return -EPERM; |
| 1470 | |
| 1471 | /* Find the mm_struct */ |
| 1472 | rcu_read_lock(); |
| 1473 | task = pid ? find_task_by_vpid(pid) : current; |
| 1474 | if (!task) { |
| 1475 | rcu_read_unlock(); |
| 1476 | return -ESRCH; |
| 1477 | } |
| 1478 | get_task_struct(task); |
| 1479 | |
| 1480 | /* |
| 1481 | * Check if this process has the right to modify the specified |
| 1482 | * process. The right exists if the process has administrative |
| 1483 | * capabilities, superuser privileges or the same |
| 1484 | * userid as the target process. |
| 1485 | */ |
| 1486 | tcred = __task_cred(task); |
| 1487 | if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) && |
| 1488 | !uid_eq(cred->uid, tcred->suid) && !uid_eq(cred->uid, tcred->uid) && |
| 1489 | !capable(CAP_SYS_NICE)) { |
| 1490 | rcu_read_unlock(); |
| 1491 | err = -EPERM; |
| 1492 | goto out; |
| 1493 | } |
| 1494 | rcu_read_unlock(); |
| 1495 | |
| 1496 | err = security_task_movememory(task); |
| 1497 | if (err) |
| 1498 | goto out; |
| 1499 | |
| 1500 | task_nodes = cpuset_mems_allowed(task); |
| 1501 | mm = get_task_mm(task); |
| 1502 | put_task_struct(task); |
| 1503 | |
| 1504 | if (!mm) |
| 1505 | return -EINVAL; |
| 1506 | |
| 1507 | if (nodes) |
| 1508 | err = do_pages_move(mm, task_nodes, nr_pages, pages, |
| 1509 | nodes, status, flags); |
| 1510 | else |
| 1511 | err = do_pages_stat(mm, nr_pages, pages, status); |
| 1512 | |
| 1513 | mmput(mm); |
| 1514 | return err; |
| 1515 | |
| 1516 | out: |
| 1517 | put_task_struct(task); |
| 1518 | return err; |
| 1519 | } |
| 1520 | |
| 1521 | /* |
| 1522 | * Call migration functions in the vma_ops that may prepare |
| 1523 | * memory in a vm for migration. migration functions may perform |
| 1524 | * the migration for vmas that do not have an underlying page struct. |
| 1525 | */ |
| 1526 | int migrate_vmas(struct mm_struct *mm, const nodemask_t *to, |
| 1527 | const nodemask_t *from, unsigned long flags) |
| 1528 | { |
| 1529 | struct vm_area_struct *vma; |
| 1530 | int err = 0; |
| 1531 | |
| 1532 | for (vma = mm->mmap; vma && !err; vma = vma->vm_next) { |
| 1533 | if (vma->vm_ops && vma->vm_ops->migrate) { |
| 1534 | err = vma->vm_ops->migrate(vma, to, from, flags); |
| 1535 | if (err) |
| 1536 | break; |
| 1537 | } |
| 1538 | } |
| 1539 | return err; |
| 1540 | } |
| 1541 | |
| 1542 | #ifdef CONFIG_NUMA_BALANCING |
| 1543 | /* |
| 1544 | * Returns true if this is a safe migration target node for misplaced NUMA |
| 1545 | * pages. Currently it only checks the watermarks which crude |
| 1546 | */ |
| 1547 | static bool migrate_balanced_pgdat(struct pglist_data *pgdat, |
| 1548 | unsigned long nr_migrate_pages) |
| 1549 | { |
| 1550 | int z; |
| 1551 | for (z = pgdat->nr_zones - 1; z >= 0; z--) { |
| 1552 | struct zone *zone = pgdat->node_zones + z; |
| 1553 | |
| 1554 | if (!populated_zone(zone)) |
| 1555 | continue; |
| 1556 | |
| 1557 | if (!zone_reclaimable(zone)) |
| 1558 | continue; |
| 1559 | |
| 1560 | /* Avoid waking kswapd by allocating pages_to_migrate pages. */ |
| 1561 | if (!zone_watermark_ok(zone, 0, |
| 1562 | high_wmark_pages(zone) + |
| 1563 | nr_migrate_pages, |
| 1564 | 0, 0)) |
| 1565 | continue; |
| 1566 | return true; |
| 1567 | } |
| 1568 | return false; |
| 1569 | } |
| 1570 | |
| 1571 | static struct page *alloc_misplaced_dst_page(struct page *page, |
| 1572 | unsigned long data, |
| 1573 | int **result) |
| 1574 | { |
| 1575 | int nid = (int) data; |
| 1576 | struct page *newpage; |
| 1577 | |
| 1578 | newpage = alloc_pages_exact_node(nid, |
| 1579 | (GFP_HIGHUSER_MOVABLE | |
| 1580 | __GFP_THISNODE | __GFP_NOMEMALLOC | |
| 1581 | __GFP_NORETRY | __GFP_NOWARN) & |
| 1582 | ~GFP_IOFS, 0); |
| 1583 | |
| 1584 | return newpage; |
| 1585 | } |
| 1586 | |
| 1587 | /* |
| 1588 | * page migration rate limiting control. |
| 1589 | * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs |
| 1590 | * window of time. Default here says do not migrate more than 1280M per second. |
| 1591 | * If a node is rate-limited then PTE NUMA updates are also rate-limited. However |
| 1592 | * as it is faults that reset the window, pte updates will happen unconditionally |
| 1593 | * if there has not been a fault since @pteupdate_interval_millisecs after the |
| 1594 | * throttle window closed. |
| 1595 | */ |
| 1596 | static unsigned int migrate_interval_millisecs __read_mostly = 100; |
| 1597 | static unsigned int pteupdate_interval_millisecs __read_mostly = 1000; |
| 1598 | static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT); |
| 1599 | |
| 1600 | /* Returns true if NUMA migration is currently rate limited */ |
| 1601 | bool migrate_ratelimited(int node) |
| 1602 | { |
| 1603 | pg_data_t *pgdat = NODE_DATA(node); |
| 1604 | |
| 1605 | if (time_after(jiffies, pgdat->numabalancing_migrate_next_window + |
| 1606 | msecs_to_jiffies(pteupdate_interval_millisecs))) |
| 1607 | return false; |
| 1608 | |
| 1609 | if (pgdat->numabalancing_migrate_nr_pages < ratelimit_pages) |
| 1610 | return false; |
| 1611 | |
| 1612 | return true; |
| 1613 | } |
| 1614 | |
| 1615 | /* Returns true if the node is migrate rate-limited after the update */ |
| 1616 | static bool numamigrate_update_ratelimit(pg_data_t *pgdat, |
| 1617 | unsigned long nr_pages) |
| 1618 | { |
| 1619 | /* |
| 1620 | * Rate-limit the amount of data that is being migrated to a node. |
| 1621 | * Optimal placement is no good if the memory bus is saturated and |
| 1622 | * all the time is being spent migrating! |
| 1623 | */ |
| 1624 | if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) { |
| 1625 | spin_lock(&pgdat->numabalancing_migrate_lock); |
| 1626 | pgdat->numabalancing_migrate_nr_pages = 0; |
| 1627 | pgdat->numabalancing_migrate_next_window = jiffies + |
| 1628 | msecs_to_jiffies(migrate_interval_millisecs); |
| 1629 | spin_unlock(&pgdat->numabalancing_migrate_lock); |
| 1630 | } |
| 1631 | if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) { |
| 1632 | trace_mm_numa_migrate_ratelimit(current, pgdat->node_id, |
| 1633 | nr_pages); |
| 1634 | return true; |
| 1635 | } |
| 1636 | |
| 1637 | /* |
| 1638 | * This is an unlocked non-atomic update so errors are possible. |
| 1639 | * The consequences are failing to migrate when we potentiall should |
| 1640 | * have which is not severe enough to warrant locking. If it is ever |
| 1641 | * a problem, it can be converted to a per-cpu counter. |
| 1642 | */ |
| 1643 | pgdat->numabalancing_migrate_nr_pages += nr_pages; |
| 1644 | return false; |
| 1645 | } |
| 1646 | |
| 1647 | static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) |
| 1648 | { |
| 1649 | int page_lru; |
| 1650 | |
| 1651 | VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page); |
| 1652 | |
| 1653 | /* Avoid migrating to a node that is nearly full */ |
| 1654 | if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page))) |
| 1655 | return 0; |
| 1656 | |
| 1657 | if (isolate_lru_page(page)) |
| 1658 | return 0; |
| 1659 | |
| 1660 | /* |
| 1661 | * migrate_misplaced_transhuge_page() skips page migration's usual |
| 1662 | * check on page_count(), so we must do it here, now that the page |
| 1663 | * has been isolated: a GUP pin, or any other pin, prevents migration. |
| 1664 | * The expected page count is 3: 1 for page's mapcount and 1 for the |
| 1665 | * caller's pin and 1 for the reference taken by isolate_lru_page(). |
| 1666 | */ |
| 1667 | if (PageTransHuge(page) && page_count(page) != 3) { |
| 1668 | putback_lru_page(page); |
| 1669 | return 0; |
| 1670 | } |
| 1671 | |
| 1672 | page_lru = page_is_file_cache(page); |
| 1673 | mod_zone_page_state(page_zone(page), NR_ISOLATED_ANON + page_lru, |
| 1674 | hpage_nr_pages(page)); |
| 1675 | |
| 1676 | /* |
| 1677 | * Isolating the page has taken another reference, so the |
| 1678 | * caller's reference can be safely dropped without the page |
| 1679 | * disappearing underneath us during migration. |
| 1680 | */ |
| 1681 | put_page(page); |
| 1682 | return 1; |
| 1683 | } |
| 1684 | |
| 1685 | bool pmd_trans_migrating(pmd_t pmd) |
| 1686 | { |
| 1687 | struct page *page = pmd_page(pmd); |
| 1688 | return PageLocked(page); |
| 1689 | } |
| 1690 | |
| 1691 | void wait_migrate_huge_page(struct anon_vma *anon_vma, pmd_t *pmd) |
| 1692 | { |
| 1693 | struct page *page = pmd_page(*pmd); |
| 1694 | wait_on_page_locked(page); |
| 1695 | } |
| 1696 | |
| 1697 | /* |
| 1698 | * Attempt to migrate a misplaced page to the specified destination |
| 1699 | * node. Caller is expected to have an elevated reference count on |
| 1700 | * the page that will be dropped by this function before returning. |
| 1701 | */ |
| 1702 | int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma, |
| 1703 | int node) |
| 1704 | { |
| 1705 | pg_data_t *pgdat = NODE_DATA(node); |
| 1706 | int isolated; |
| 1707 | int nr_remaining; |
| 1708 | LIST_HEAD(migratepages); |
| 1709 | |
| 1710 | /* |
| 1711 | * Don't migrate file pages that are mapped in multiple processes |
| 1712 | * with execute permissions as they are probably shared libraries. |
| 1713 | */ |
| 1714 | if (page_mapcount(page) != 1 && page_is_file_cache(page) && |
| 1715 | (vma->vm_flags & VM_EXEC)) |
| 1716 | goto out; |
| 1717 | |
| 1718 | /* |
| 1719 | * Rate-limit the amount of data that is being migrated to a node. |
| 1720 | * Optimal placement is no good if the memory bus is saturated and |
| 1721 | * all the time is being spent migrating! |
| 1722 | */ |
| 1723 | if (numamigrate_update_ratelimit(pgdat, 1)) |
| 1724 | goto out; |
| 1725 | |
| 1726 | isolated = numamigrate_isolate_page(pgdat, page); |
| 1727 | if (!isolated) |
| 1728 | goto out; |
| 1729 | |
| 1730 | list_add(&page->lru, &migratepages); |
| 1731 | nr_remaining = migrate_pages(&migratepages, alloc_misplaced_dst_page, |
| 1732 | node, MIGRATE_ASYNC, MR_NUMA_MISPLACED); |
| 1733 | if (nr_remaining) { |
| 1734 | if (!list_empty(&migratepages)) { |
| 1735 | list_del(&page->lru); |
| 1736 | dec_zone_page_state(page, NR_ISOLATED_ANON + |
| 1737 | page_is_file_cache(page)); |
| 1738 | putback_lru_page(page); |
| 1739 | } |
| 1740 | isolated = 0; |
| 1741 | } else |
| 1742 | count_vm_numa_event(NUMA_PAGE_MIGRATE); |
| 1743 | BUG_ON(!list_empty(&migratepages)); |
| 1744 | return isolated; |
| 1745 | |
| 1746 | out: |
| 1747 | put_page(page); |
| 1748 | return 0; |
| 1749 | } |
| 1750 | #endif /* CONFIG_NUMA_BALANCING */ |
| 1751 | |
| 1752 | #if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE) |
| 1753 | /* |
| 1754 | * Migrates a THP to a given target node. page must be locked and is unlocked |
| 1755 | * before returning. |
| 1756 | */ |
| 1757 | int migrate_misplaced_transhuge_page(struct mm_struct *mm, |
| 1758 | struct vm_area_struct *vma, |
| 1759 | pmd_t *pmd, pmd_t entry, |
| 1760 | unsigned long address, |
| 1761 | struct page *page, int node) |
| 1762 | { |
| 1763 | spinlock_t *ptl; |
| 1764 | pg_data_t *pgdat = NODE_DATA(node); |
| 1765 | int isolated = 0; |
| 1766 | struct page *new_page = NULL; |
| 1767 | struct mem_cgroup *memcg = NULL; |
| 1768 | int page_lru = page_is_file_cache(page); |
| 1769 | unsigned long mmun_start = address & HPAGE_PMD_MASK; |
| 1770 | unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE; |
| 1771 | pmd_t orig_entry; |
| 1772 | |
| 1773 | /* |
| 1774 | * Rate-limit the amount of data that is being migrated to a node. |
| 1775 | * Optimal placement is no good if the memory bus is saturated and |
| 1776 | * all the time is being spent migrating! |
| 1777 | */ |
| 1778 | if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR)) |
| 1779 | goto out_dropref; |
| 1780 | |
| 1781 | new_page = alloc_pages_node(node, |
| 1782 | (GFP_TRANSHUGE | __GFP_THISNODE) & ~__GFP_WAIT, |
| 1783 | HPAGE_PMD_ORDER); |
| 1784 | if (!new_page) |
| 1785 | goto out_fail; |
| 1786 | |
| 1787 | isolated = numamigrate_isolate_page(pgdat, page); |
| 1788 | if (!isolated) { |
| 1789 | put_page(new_page); |
| 1790 | goto out_fail; |
| 1791 | } |
| 1792 | |
| 1793 | if (mm_tlb_flush_pending(mm)) |
| 1794 | flush_tlb_range(vma, mmun_start, mmun_end); |
| 1795 | |
| 1796 | /* Prepare a page as a migration target */ |
| 1797 | __set_page_locked(new_page); |
| 1798 | SetPageSwapBacked(new_page); |
| 1799 | |
| 1800 | /* anon mapping, we can simply copy page->mapping to the new page: */ |
| 1801 | new_page->mapping = page->mapping; |
| 1802 | new_page->index = page->index; |
| 1803 | migrate_page_copy(new_page, page); |
| 1804 | WARN_ON(PageLRU(new_page)); |
| 1805 | |
| 1806 | /* Recheck the target PMD */ |
| 1807 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
| 1808 | ptl = pmd_lock(mm, pmd); |
| 1809 | if (unlikely(!pmd_same(*pmd, entry) || page_count(page) != 2)) { |
| 1810 | fail_putback: |
| 1811 | spin_unlock(ptl); |
| 1812 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
| 1813 | |
| 1814 | /* Reverse changes made by migrate_page_copy() */ |
| 1815 | if (TestClearPageActive(new_page)) |
| 1816 | SetPageActive(page); |
| 1817 | if (TestClearPageUnevictable(new_page)) |
| 1818 | SetPageUnevictable(page); |
| 1819 | mlock_migrate_page(page, new_page); |
| 1820 | |
| 1821 | unlock_page(new_page); |
| 1822 | put_page(new_page); /* Free it */ |
| 1823 | |
| 1824 | /* Retake the callers reference and putback on LRU */ |
| 1825 | get_page(page); |
| 1826 | putback_lru_page(page); |
| 1827 | mod_zone_page_state(page_zone(page), |
| 1828 | NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR); |
| 1829 | |
| 1830 | goto out_unlock; |
| 1831 | } |
| 1832 | |
| 1833 | /* |
| 1834 | * Traditional migration needs to prepare the memcg charge |
| 1835 | * transaction early to prevent the old page from being |
| 1836 | * uncharged when installing migration entries. Here we can |
| 1837 | * save the potential rollback and start the charge transfer |
| 1838 | * only when migration is already known to end successfully. |
| 1839 | */ |
| 1840 | mem_cgroup_prepare_migration(page, new_page, &memcg); |
| 1841 | |
| 1842 | orig_entry = *pmd; |
| 1843 | entry = mk_pmd(new_page, vma->vm_page_prot); |
| 1844 | entry = pmd_mkhuge(entry); |
| 1845 | entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); |
| 1846 | |
| 1847 | /* |
| 1848 | * Clear the old entry under pagetable lock and establish the new PTE. |
| 1849 | * Any parallel GUP will either observe the old page blocking on the |
| 1850 | * page lock, block on the page table lock or observe the new page. |
| 1851 | * The SetPageUptodate on the new page and page_add_new_anon_rmap |
| 1852 | * guarantee the copy is visible before the pagetable update. |
| 1853 | */ |
| 1854 | flush_cache_range(vma, mmun_start, mmun_end); |
| 1855 | page_add_new_anon_rmap(new_page, vma, mmun_start); |
| 1856 | pmdp_clear_flush(vma, mmun_start, pmd); |
| 1857 | set_pmd_at(mm, mmun_start, pmd, entry); |
| 1858 | flush_tlb_range(vma, mmun_start, mmun_end); |
| 1859 | update_mmu_cache_pmd(vma, address, &entry); |
| 1860 | |
| 1861 | if (page_count(page) != 2) { |
| 1862 | set_pmd_at(mm, mmun_start, pmd, orig_entry); |
| 1863 | flush_tlb_range(vma, mmun_start, mmun_end); |
| 1864 | update_mmu_cache_pmd(vma, address, &entry); |
| 1865 | page_remove_rmap(new_page); |
| 1866 | goto fail_putback; |
| 1867 | } |
| 1868 | |
| 1869 | page_remove_rmap(page); |
| 1870 | |
| 1871 | /* |
| 1872 | * Finish the charge transaction under the page table lock to |
| 1873 | * prevent split_huge_page() from dividing up the charge |
| 1874 | * before it's fully transferred to the new page. |
| 1875 | */ |
| 1876 | mem_cgroup_end_migration(memcg, page, new_page, true); |
| 1877 | spin_unlock(ptl); |
| 1878 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
| 1879 | |
| 1880 | unlock_page(new_page); |
| 1881 | unlock_page(page); |
| 1882 | put_page(page); /* Drop the rmap reference */ |
| 1883 | put_page(page); /* Drop the LRU isolation reference */ |
| 1884 | |
| 1885 | count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR); |
| 1886 | count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR); |
| 1887 | |
| 1888 | mod_zone_page_state(page_zone(page), |
| 1889 | NR_ISOLATED_ANON + page_lru, |
| 1890 | -HPAGE_PMD_NR); |
| 1891 | return isolated; |
| 1892 | |
| 1893 | out_fail: |
| 1894 | count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); |
| 1895 | out_dropref: |
| 1896 | ptl = pmd_lock(mm, pmd); |
| 1897 | if (pmd_same(*pmd, entry)) { |
| 1898 | entry = pmd_mknonnuma(entry); |
| 1899 | set_pmd_at(mm, mmun_start, pmd, entry); |
| 1900 | update_mmu_cache_pmd(vma, address, &entry); |
| 1901 | } |
| 1902 | spin_unlock(ptl); |
| 1903 | |
| 1904 | out_unlock: |
| 1905 | unlock_page(page); |
| 1906 | put_page(page); |
| 1907 | return 0; |
| 1908 | } |
| 1909 | #endif /* CONFIG_NUMA_BALANCING */ |
| 1910 | |
| 1911 | #endif /* CONFIG_NUMA */ |