1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2009 Red Hat, Inc. 4 */ 5 6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 7 8 #include <linux/mm.h> 9 #include <linux/sched.h> 10 #include <linux/sched/coredump.h> 11 #include <linux/sched/numa_balancing.h> 12 #include <linux/highmem.h> 13 #include <linux/hugetlb.h> 14 #include <linux/mmu_notifier.h> 15 #include <linux/rmap.h> 16 #include <linux/swap.h> 17 #include <linux/shrinker.h> 18 #include <linux/mm_inline.h> 19 #include <linux/swapops.h> 20 #include <linux/dax.h> 21 #include <linux/khugepaged.h> 22 #include <linux/freezer.h> 23 #include <linux/pfn_t.h> 24 #include <linux/mman.h> 25 #include <linux/memremap.h> 26 #include <linux/pagemap.h> 27 #include <linux/debugfs.h> 28 #include <linux/migrate.h> 29 #include <linux/hashtable.h> 30 #include <linux/userfaultfd_k.h> 31 #include <linux/page_idle.h> 32 #include <linux/shmem_fs.h> 33 #include <linux/oom.h> 34 #include <linux/numa.h> 35 #include <linux/page_owner.h> 36 37 #include <asm/tlb.h> 38 #include <asm/pgalloc.h> 39 #include "internal.h" 40 41 /* 42 * By default, transparent hugepage support is disabled in order to avoid 43 * risking an increased memory footprint for applications that are not 44 * guaranteed to benefit from it. When transparent hugepage support is 45 * enabled, it is for all mappings, and khugepaged scans all mappings. 46 * Defrag is invoked by khugepaged hugepage allocations and by page faults 47 * for all hugepage allocations. 48 */ 49 unsigned long transparent_hugepage_flags __read_mostly = 50 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 51 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 52 #endif 53 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 55 #endif 56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 59 60 static struct shrinker deferred_split_shrinker; 61 62 static atomic_t huge_zero_refcount; 63 struct page *huge_zero_page __read_mostly; 64 65 bool transparent_hugepage_enabled(struct vm_area_struct *vma) 66 { 67 /* The addr is used to check if the vma size fits */ 68 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE; 69 70 if (!transhuge_vma_suitable(vma, addr)) 71 return false; 72 if (vma_is_anonymous(vma)) 73 return __transparent_hugepage_enabled(vma); 74 if (vma_is_shmem(vma)) 75 return shmem_huge_enabled(vma); 76 77 return false; 78 } 79 80 static struct page *get_huge_zero_page(void) 81 { 82 struct page *zero_page; 83 retry: 84 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 85 return READ_ONCE(huge_zero_page); 86 87 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 88 HPAGE_PMD_ORDER); 89 if (!zero_page) { 90 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 91 return NULL; 92 } 93 count_vm_event(THP_ZERO_PAGE_ALLOC); 94 preempt_disable(); 95 if (cmpxchg(&huge_zero_page, NULL, zero_page)) { 96 preempt_enable(); 97 __free_pages(zero_page, compound_order(zero_page)); 98 goto retry; 99 } 100 101 /* We take additional reference here. It will be put back by shrinker */ 102 atomic_set(&huge_zero_refcount, 2); 103 preempt_enable(); 104 return READ_ONCE(huge_zero_page); 105 } 106 107 static void put_huge_zero_page(void) 108 { 109 /* 110 * Counter should never go to zero here. Only shrinker can put 111 * last reference. 112 */ 113 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 114 } 115 116 struct page *mm_get_huge_zero_page(struct mm_struct *mm) 117 { 118 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 119 return READ_ONCE(huge_zero_page); 120 121 if (!get_huge_zero_page()) 122 return NULL; 123 124 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 125 put_huge_zero_page(); 126 127 return READ_ONCE(huge_zero_page); 128 } 129 130 void mm_put_huge_zero_page(struct mm_struct *mm) 131 { 132 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 133 put_huge_zero_page(); 134 } 135 136 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 137 struct shrink_control *sc) 138 { 139 /* we can free zero page only if last reference remains */ 140 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 141 } 142 143 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 144 struct shrink_control *sc) 145 { 146 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 147 struct page *zero_page = xchg(&huge_zero_page, NULL); 148 BUG_ON(zero_page == NULL); 149 __free_pages(zero_page, compound_order(zero_page)); 150 return HPAGE_PMD_NR; 151 } 152 153 return 0; 154 } 155 156 static struct shrinker huge_zero_page_shrinker = { 157 .count_objects = shrink_huge_zero_page_count, 158 .scan_objects = shrink_huge_zero_page_scan, 159 .seeks = DEFAULT_SEEKS, 160 }; 161 162 #ifdef CONFIG_SYSFS 163 static ssize_t enabled_show(struct kobject *kobj, 164 struct kobj_attribute *attr, char *buf) 165 { 166 const char *output; 167 168 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 169 output = "[always] madvise never"; 170 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 171 &transparent_hugepage_flags)) 172 output = "always [madvise] never"; 173 else 174 output = "always madvise [never]"; 175 176 return sysfs_emit(buf, "%s\n", output); 177 } 178 179 static ssize_t enabled_store(struct kobject *kobj, 180 struct kobj_attribute *attr, 181 const char *buf, size_t count) 182 { 183 ssize_t ret = count; 184 185 if (sysfs_streq(buf, "always")) { 186 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 187 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 188 } else if (sysfs_streq(buf, "madvise")) { 189 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 190 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 191 } else if (sysfs_streq(buf, "never")) { 192 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 193 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 194 } else 195 ret = -EINVAL; 196 197 if (ret > 0) { 198 int err = start_stop_khugepaged(); 199 if (err) 200 ret = err; 201 } 202 return ret; 203 } 204 static struct kobj_attribute enabled_attr = 205 __ATTR(enabled, 0644, enabled_show, enabled_store); 206 207 ssize_t single_hugepage_flag_show(struct kobject *kobj, 208 struct kobj_attribute *attr, char *buf, 209 enum transparent_hugepage_flag flag) 210 { 211 return sysfs_emit(buf, "%d\n", 212 !!test_bit(flag, &transparent_hugepage_flags)); 213 } 214 215 ssize_t single_hugepage_flag_store(struct kobject *kobj, 216 struct kobj_attribute *attr, 217 const char *buf, size_t count, 218 enum transparent_hugepage_flag flag) 219 { 220 unsigned long value; 221 int ret; 222 223 ret = kstrtoul(buf, 10, &value); 224 if (ret < 0) 225 return ret; 226 if (value > 1) 227 return -EINVAL; 228 229 if (value) 230 set_bit(flag, &transparent_hugepage_flags); 231 else 232 clear_bit(flag, &transparent_hugepage_flags); 233 234 return count; 235 } 236 237 static ssize_t defrag_show(struct kobject *kobj, 238 struct kobj_attribute *attr, char *buf) 239 { 240 const char *output; 241 242 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 243 &transparent_hugepage_flags)) 244 output = "[always] defer defer+madvise madvise never"; 245 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 246 &transparent_hugepage_flags)) 247 output = "always [defer] defer+madvise madvise never"; 248 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 249 &transparent_hugepage_flags)) 250 output = "always defer [defer+madvise] madvise never"; 251 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 252 &transparent_hugepage_flags)) 253 output = "always defer defer+madvise [madvise] never"; 254 else 255 output = "always defer defer+madvise madvise [never]"; 256 257 return sysfs_emit(buf, "%s\n", output); 258 } 259 260 static ssize_t defrag_store(struct kobject *kobj, 261 struct kobj_attribute *attr, 262 const char *buf, size_t count) 263 { 264 if (sysfs_streq(buf, "always")) { 265 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 266 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 268 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 269 } else if (sysfs_streq(buf, "defer+madvise")) { 270 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 271 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 272 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 273 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 274 } else if (sysfs_streq(buf, "defer")) { 275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 276 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 277 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 278 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 279 } else if (sysfs_streq(buf, "madvise")) { 280 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 281 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 282 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 283 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 284 } else if (sysfs_streq(buf, "never")) { 285 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 286 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 287 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 288 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 289 } else 290 return -EINVAL; 291 292 return count; 293 } 294 static struct kobj_attribute defrag_attr = 295 __ATTR(defrag, 0644, defrag_show, defrag_store); 296 297 static ssize_t use_zero_page_show(struct kobject *kobj, 298 struct kobj_attribute *attr, char *buf) 299 { 300 return single_hugepage_flag_show(kobj, attr, buf, 301 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 302 } 303 static ssize_t use_zero_page_store(struct kobject *kobj, 304 struct kobj_attribute *attr, const char *buf, size_t count) 305 { 306 return single_hugepage_flag_store(kobj, attr, buf, count, 307 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 308 } 309 static struct kobj_attribute use_zero_page_attr = 310 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); 311 312 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 313 struct kobj_attribute *attr, char *buf) 314 { 315 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); 316 } 317 static struct kobj_attribute hpage_pmd_size_attr = 318 __ATTR_RO(hpage_pmd_size); 319 320 static struct attribute *hugepage_attr[] = { 321 &enabled_attr.attr, 322 &defrag_attr.attr, 323 &use_zero_page_attr.attr, 324 &hpage_pmd_size_attr.attr, 325 #ifdef CONFIG_SHMEM 326 &shmem_enabled_attr.attr, 327 #endif 328 NULL, 329 }; 330 331 static const struct attribute_group hugepage_attr_group = { 332 .attrs = hugepage_attr, 333 }; 334 335 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 336 { 337 int err; 338 339 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 340 if (unlikely(!*hugepage_kobj)) { 341 pr_err("failed to create transparent hugepage kobject\n"); 342 return -ENOMEM; 343 } 344 345 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 346 if (err) { 347 pr_err("failed to register transparent hugepage group\n"); 348 goto delete_obj; 349 } 350 351 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 352 if (err) { 353 pr_err("failed to register transparent hugepage group\n"); 354 goto remove_hp_group; 355 } 356 357 return 0; 358 359 remove_hp_group: 360 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 361 delete_obj: 362 kobject_put(*hugepage_kobj); 363 return err; 364 } 365 366 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 367 { 368 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 369 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 370 kobject_put(hugepage_kobj); 371 } 372 #else 373 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 374 { 375 return 0; 376 } 377 378 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 379 { 380 } 381 #endif /* CONFIG_SYSFS */ 382 383 static int __init hugepage_init(void) 384 { 385 int err; 386 struct kobject *hugepage_kobj; 387 388 if (!has_transparent_hugepage()) { 389 /* 390 * Hardware doesn't support hugepages, hence disable 391 * DAX PMD support. 392 */ 393 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX; 394 return -EINVAL; 395 } 396 397 /* 398 * hugepages can't be allocated by the buddy allocator 399 */ 400 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); 401 /* 402 * we use page->mapping and page->index in second tail page 403 * as list_head: assuming THP order >= 2 404 */ 405 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); 406 407 err = hugepage_init_sysfs(&hugepage_kobj); 408 if (err) 409 goto err_sysfs; 410 411 err = khugepaged_init(); 412 if (err) 413 goto err_slab; 414 415 err = register_shrinker(&huge_zero_page_shrinker); 416 if (err) 417 goto err_hzp_shrinker; 418 err = register_shrinker(&deferred_split_shrinker); 419 if (err) 420 goto err_split_shrinker; 421 422 /* 423 * By default disable transparent hugepages on smaller systems, 424 * where the extra memory used could hurt more than TLB overhead 425 * is likely to save. The admin can still enable it through /sys. 426 */ 427 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 428 transparent_hugepage_flags = 0; 429 return 0; 430 } 431 432 err = start_stop_khugepaged(); 433 if (err) 434 goto err_khugepaged; 435 436 return 0; 437 err_khugepaged: 438 unregister_shrinker(&deferred_split_shrinker); 439 err_split_shrinker: 440 unregister_shrinker(&huge_zero_page_shrinker); 441 err_hzp_shrinker: 442 khugepaged_destroy(); 443 err_slab: 444 hugepage_exit_sysfs(hugepage_kobj); 445 err_sysfs: 446 return err; 447 } 448 subsys_initcall(hugepage_init); 449 450 static int __init setup_transparent_hugepage(char *str) 451 { 452 int ret = 0; 453 if (!str) 454 goto out; 455 if (!strcmp(str, "always")) { 456 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 457 &transparent_hugepage_flags); 458 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 459 &transparent_hugepage_flags); 460 ret = 1; 461 } else if (!strcmp(str, "madvise")) { 462 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 463 &transparent_hugepage_flags); 464 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 465 &transparent_hugepage_flags); 466 ret = 1; 467 } else if (!strcmp(str, "never")) { 468 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 469 &transparent_hugepage_flags); 470 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 471 &transparent_hugepage_flags); 472 ret = 1; 473 } 474 out: 475 if (!ret) 476 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 477 return ret; 478 } 479 __setup("transparent_hugepage=", setup_transparent_hugepage); 480 481 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 482 { 483 if (likely(vma->vm_flags & VM_WRITE)) 484 pmd = pmd_mkwrite(pmd); 485 return pmd; 486 } 487 488 #ifdef CONFIG_MEMCG 489 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 490 { 491 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 492 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 493 494 if (memcg) 495 return &memcg->deferred_split_queue; 496 else 497 return &pgdat->deferred_split_queue; 498 } 499 #else 500 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 501 { 502 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 503 504 return &pgdat->deferred_split_queue; 505 } 506 #endif 507 508 void prep_transhuge_page(struct page *page) 509 { 510 /* 511 * we use page->mapping and page->indexlru in second tail page 512 * as list_head: assuming THP order >= 2 513 */ 514 515 INIT_LIST_HEAD(page_deferred_list(page)); 516 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); 517 } 518 519 bool is_transparent_hugepage(struct page *page) 520 { 521 if (!PageCompound(page)) 522 return false; 523 524 page = compound_head(page); 525 return is_huge_zero_page(page) || 526 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR; 527 } 528 EXPORT_SYMBOL_GPL(is_transparent_hugepage); 529 530 static unsigned long __thp_get_unmapped_area(struct file *filp, 531 unsigned long addr, unsigned long len, 532 loff_t off, unsigned long flags, unsigned long size) 533 { 534 loff_t off_end = off + len; 535 loff_t off_align = round_up(off, size); 536 unsigned long len_pad, ret; 537 538 if (off_end <= off_align || (off_end - off_align) < size) 539 return 0; 540 541 len_pad = len + size; 542 if (len_pad < len || (off + len_pad) < off) 543 return 0; 544 545 ret = current->mm->get_unmapped_area(filp, addr, len_pad, 546 off >> PAGE_SHIFT, flags); 547 548 /* 549 * The failure might be due to length padding. The caller will retry 550 * without the padding. 551 */ 552 if (IS_ERR_VALUE(ret)) 553 return 0; 554 555 /* 556 * Do not try to align to THP boundary if allocation at the address 557 * hint succeeds. 558 */ 559 if (ret == addr) 560 return addr; 561 562 ret += (off - ret) & (size - 1); 563 return ret; 564 } 565 566 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 567 unsigned long len, unsigned long pgoff, unsigned long flags) 568 { 569 unsigned long ret; 570 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 571 572 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD)) 573 goto out; 574 575 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE); 576 if (ret) 577 return ret; 578 out: 579 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 580 } 581 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 582 583 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 584 struct page *page, gfp_t gfp) 585 { 586 struct vm_area_struct *vma = vmf->vma; 587 pgtable_t pgtable; 588 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 589 vm_fault_t ret = 0; 590 591 VM_BUG_ON_PAGE(!PageCompound(page), page); 592 593 if (mem_cgroup_charge(page, vma->vm_mm, gfp)) { 594 put_page(page); 595 count_vm_event(THP_FAULT_FALLBACK); 596 count_vm_event(THP_FAULT_FALLBACK_CHARGE); 597 return VM_FAULT_FALLBACK; 598 } 599 cgroup_throttle_swaprate(page, gfp); 600 601 pgtable = pte_alloc_one(vma->vm_mm); 602 if (unlikely(!pgtable)) { 603 ret = VM_FAULT_OOM; 604 goto release; 605 } 606 607 clear_huge_page(page, vmf->address, HPAGE_PMD_NR); 608 /* 609 * The memory barrier inside __SetPageUptodate makes sure that 610 * clear_huge_page writes become visible before the set_pmd_at() 611 * write. 612 */ 613 __SetPageUptodate(page); 614 615 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 616 if (unlikely(!pmd_none(*vmf->pmd))) { 617 goto unlock_release; 618 } else { 619 pmd_t entry; 620 621 ret = check_stable_address_space(vma->vm_mm); 622 if (ret) 623 goto unlock_release; 624 625 /* Deliver the page fault to userland */ 626 if (userfaultfd_missing(vma)) { 627 vm_fault_t ret2; 628 629 spin_unlock(vmf->ptl); 630 put_page(page); 631 pte_free(vma->vm_mm, pgtable); 632 ret2 = handle_userfault(vmf, VM_UFFD_MISSING); 633 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK); 634 return ret2; 635 } 636 637 entry = mk_huge_pmd(page, vma->vm_page_prot); 638 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 639 page_add_new_anon_rmap(page, vma, haddr, true); 640 lru_cache_add_inactive_or_unevictable(page, vma); 641 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 642 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 643 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 644 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 645 mm_inc_nr_ptes(vma->vm_mm); 646 spin_unlock(vmf->ptl); 647 count_vm_event(THP_FAULT_ALLOC); 648 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); 649 } 650 651 return 0; 652 unlock_release: 653 spin_unlock(vmf->ptl); 654 release: 655 if (pgtable) 656 pte_free(vma->vm_mm, pgtable); 657 put_page(page); 658 return ret; 659 660 } 661 662 /* 663 * always: directly stall for all thp allocations 664 * defer: wake kswapd and fail if not immediately available 665 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 666 * fail if not immediately available 667 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 668 * available 669 * never: never stall for any thp allocation 670 */ 671 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) 672 { 673 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); 674 675 /* Always do synchronous compaction */ 676 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 677 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 678 679 /* Kick kcompactd and fail quickly */ 680 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 681 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; 682 683 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 684 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 685 return GFP_TRANSHUGE_LIGHT | 686 (vma_madvised ? __GFP_DIRECT_RECLAIM : 687 __GFP_KSWAPD_RECLAIM); 688 689 /* Only do synchronous compaction if madvised */ 690 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 691 return GFP_TRANSHUGE_LIGHT | 692 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 693 694 return GFP_TRANSHUGE_LIGHT; 695 } 696 697 /* Caller must hold page table lock. */ 698 static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, 699 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 700 struct page *zero_page) 701 { 702 pmd_t entry; 703 if (!pmd_none(*pmd)) 704 return; 705 entry = mk_pmd(zero_page, vma->vm_page_prot); 706 entry = pmd_mkhuge(entry); 707 if (pgtable) 708 pgtable_trans_huge_deposit(mm, pmd, pgtable); 709 set_pmd_at(mm, haddr, pmd, entry); 710 mm_inc_nr_ptes(mm); 711 } 712 713 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 714 { 715 struct vm_area_struct *vma = vmf->vma; 716 gfp_t gfp; 717 struct page *page; 718 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 719 720 if (!transhuge_vma_suitable(vma, haddr)) 721 return VM_FAULT_FALLBACK; 722 if (unlikely(anon_vma_prepare(vma))) 723 return VM_FAULT_OOM; 724 if (unlikely(khugepaged_enter(vma, vma->vm_flags))) 725 return VM_FAULT_OOM; 726 if (!(vmf->flags & FAULT_FLAG_WRITE) && 727 !mm_forbids_zeropage(vma->vm_mm) && 728 transparent_hugepage_use_zero_page()) { 729 pgtable_t pgtable; 730 struct page *zero_page; 731 vm_fault_t ret; 732 pgtable = pte_alloc_one(vma->vm_mm); 733 if (unlikely(!pgtable)) 734 return VM_FAULT_OOM; 735 zero_page = mm_get_huge_zero_page(vma->vm_mm); 736 if (unlikely(!zero_page)) { 737 pte_free(vma->vm_mm, pgtable); 738 count_vm_event(THP_FAULT_FALLBACK); 739 return VM_FAULT_FALLBACK; 740 } 741 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 742 ret = 0; 743 if (pmd_none(*vmf->pmd)) { 744 ret = check_stable_address_space(vma->vm_mm); 745 if (ret) { 746 spin_unlock(vmf->ptl); 747 pte_free(vma->vm_mm, pgtable); 748 } else if (userfaultfd_missing(vma)) { 749 spin_unlock(vmf->ptl); 750 pte_free(vma->vm_mm, pgtable); 751 ret = handle_userfault(vmf, VM_UFFD_MISSING); 752 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 753 } else { 754 set_huge_zero_page(pgtable, vma->vm_mm, vma, 755 haddr, vmf->pmd, zero_page); 756 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 757 spin_unlock(vmf->ptl); 758 } 759 } else { 760 spin_unlock(vmf->ptl); 761 pte_free(vma->vm_mm, pgtable); 762 } 763 return ret; 764 } 765 gfp = vma_thp_gfp_mask(vma); 766 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); 767 if (unlikely(!page)) { 768 count_vm_event(THP_FAULT_FALLBACK); 769 return VM_FAULT_FALLBACK; 770 } 771 prep_transhuge_page(page); 772 return __do_huge_pmd_anonymous_page(vmf, page, gfp); 773 } 774 775 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 776 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 777 pgtable_t pgtable) 778 { 779 struct mm_struct *mm = vma->vm_mm; 780 pmd_t entry; 781 spinlock_t *ptl; 782 783 ptl = pmd_lock(mm, pmd); 784 if (!pmd_none(*pmd)) { 785 if (write) { 786 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 787 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 788 goto out_unlock; 789 } 790 entry = pmd_mkyoung(*pmd); 791 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 792 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 793 update_mmu_cache_pmd(vma, addr, pmd); 794 } 795 796 goto out_unlock; 797 } 798 799 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 800 if (pfn_t_devmap(pfn)) 801 entry = pmd_mkdevmap(entry); 802 if (write) { 803 entry = pmd_mkyoung(pmd_mkdirty(entry)); 804 entry = maybe_pmd_mkwrite(entry, vma); 805 } 806 807 if (pgtable) { 808 pgtable_trans_huge_deposit(mm, pmd, pgtable); 809 mm_inc_nr_ptes(mm); 810 pgtable = NULL; 811 } 812 813 set_pmd_at(mm, addr, pmd, entry); 814 update_mmu_cache_pmd(vma, addr, pmd); 815 816 out_unlock: 817 spin_unlock(ptl); 818 if (pgtable) 819 pte_free(mm, pgtable); 820 } 821 822 /** 823 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn 824 * @vmf: Structure describing the fault 825 * @pfn: pfn to insert 826 * @pgprot: page protection to use 827 * @write: whether it's a write fault 828 * 829 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and 830 * also consult the vmf_insert_mixed_prot() documentation when 831 * @pgprot != @vmf->vma->vm_page_prot. 832 * 833 * Return: vm_fault_t value. 834 */ 835 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn, 836 pgprot_t pgprot, bool write) 837 { 838 unsigned long addr = vmf->address & PMD_MASK; 839 struct vm_area_struct *vma = vmf->vma; 840 pgtable_t pgtable = NULL; 841 842 /* 843 * If we had pmd_special, we could avoid all these restrictions, 844 * but we need to be consistent with PTEs and architectures that 845 * can't support a 'special' bit. 846 */ 847 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 848 !pfn_t_devmap(pfn)); 849 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 850 (VM_PFNMAP|VM_MIXEDMAP)); 851 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 852 853 if (addr < vma->vm_start || addr >= vma->vm_end) 854 return VM_FAULT_SIGBUS; 855 856 if (arch_needs_pgtable_deposit()) { 857 pgtable = pte_alloc_one(vma->vm_mm); 858 if (!pgtable) 859 return VM_FAULT_OOM; 860 } 861 862 track_pfn_insert(vma, &pgprot, pfn); 863 864 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 865 return VM_FAULT_NOPAGE; 866 } 867 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot); 868 869 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 870 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 871 { 872 if (likely(vma->vm_flags & VM_WRITE)) 873 pud = pud_mkwrite(pud); 874 return pud; 875 } 876 877 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 878 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) 879 { 880 struct mm_struct *mm = vma->vm_mm; 881 pud_t entry; 882 spinlock_t *ptl; 883 884 ptl = pud_lock(mm, pud); 885 if (!pud_none(*pud)) { 886 if (write) { 887 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 888 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 889 goto out_unlock; 890 } 891 entry = pud_mkyoung(*pud); 892 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 893 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 894 update_mmu_cache_pud(vma, addr, pud); 895 } 896 goto out_unlock; 897 } 898 899 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 900 if (pfn_t_devmap(pfn)) 901 entry = pud_mkdevmap(entry); 902 if (write) { 903 entry = pud_mkyoung(pud_mkdirty(entry)); 904 entry = maybe_pud_mkwrite(entry, vma); 905 } 906 set_pud_at(mm, addr, pud, entry); 907 update_mmu_cache_pud(vma, addr, pud); 908 909 out_unlock: 910 spin_unlock(ptl); 911 } 912 913 /** 914 * vmf_insert_pfn_pud_prot - insert a pud size pfn 915 * @vmf: Structure describing the fault 916 * @pfn: pfn to insert 917 * @pgprot: page protection to use 918 * @write: whether it's a write fault 919 * 920 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and 921 * also consult the vmf_insert_mixed_prot() documentation when 922 * @pgprot != @vmf->vma->vm_page_prot. 923 * 924 * Return: vm_fault_t value. 925 */ 926 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn, 927 pgprot_t pgprot, bool write) 928 { 929 unsigned long addr = vmf->address & PUD_MASK; 930 struct vm_area_struct *vma = vmf->vma; 931 932 /* 933 * If we had pud_special, we could avoid all these restrictions, 934 * but we need to be consistent with PTEs and architectures that 935 * can't support a 'special' bit. 936 */ 937 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 938 !pfn_t_devmap(pfn)); 939 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 940 (VM_PFNMAP|VM_MIXEDMAP)); 941 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 942 943 if (addr < vma->vm_start || addr >= vma->vm_end) 944 return VM_FAULT_SIGBUS; 945 946 track_pfn_insert(vma, &pgprot, pfn); 947 948 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); 949 return VM_FAULT_NOPAGE; 950 } 951 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot); 952 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 953 954 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 955 pmd_t *pmd, int flags) 956 { 957 pmd_t _pmd; 958 959 _pmd = pmd_mkyoung(*pmd); 960 if (flags & FOLL_WRITE) 961 _pmd = pmd_mkdirty(_pmd); 962 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 963 pmd, _pmd, flags & FOLL_WRITE)) 964 update_mmu_cache_pmd(vma, addr, pmd); 965 } 966 967 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 968 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 969 { 970 unsigned long pfn = pmd_pfn(*pmd); 971 struct mm_struct *mm = vma->vm_mm; 972 struct page *page; 973 974 assert_spin_locked(pmd_lockptr(mm, pmd)); 975 976 /* 977 * When we COW a devmap PMD entry, we split it into PTEs, so we should 978 * not be in this function with `flags & FOLL_COW` set. 979 */ 980 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); 981 982 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 983 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 984 (FOLL_PIN | FOLL_GET))) 985 return NULL; 986 987 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 988 return NULL; 989 990 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 991 /* pass */; 992 else 993 return NULL; 994 995 if (flags & FOLL_TOUCH) 996 touch_pmd(vma, addr, pmd, flags); 997 998 /* 999 * device mapped pages can only be returned if the 1000 * caller will manage the page reference count. 1001 */ 1002 if (!(flags & (FOLL_GET | FOLL_PIN))) 1003 return ERR_PTR(-EEXIST); 1004 1005 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 1006 *pgmap = get_dev_pagemap(pfn, *pgmap); 1007 if (!*pgmap) 1008 return ERR_PTR(-EFAULT); 1009 page = pfn_to_page(pfn); 1010 if (!try_grab_page(page, flags)) 1011 page = ERR_PTR(-ENOMEM); 1012 1013 return page; 1014 } 1015 1016 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1017 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1018 struct vm_area_struct *vma) 1019 { 1020 spinlock_t *dst_ptl, *src_ptl; 1021 struct page *src_page; 1022 pmd_t pmd; 1023 pgtable_t pgtable = NULL; 1024 int ret = -ENOMEM; 1025 1026 /* Skip if can be re-fill on fault */ 1027 if (!vma_is_anonymous(vma)) 1028 return 0; 1029 1030 pgtable = pte_alloc_one(dst_mm); 1031 if (unlikely(!pgtable)) 1032 goto out; 1033 1034 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1035 src_ptl = pmd_lockptr(src_mm, src_pmd); 1036 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1037 1038 ret = -EAGAIN; 1039 pmd = *src_pmd; 1040 1041 /* 1042 * Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA 1043 * does not have the VM_UFFD_WP, which means that the uffd 1044 * fork event is not enabled. 1045 */ 1046 if (!(vma->vm_flags & VM_UFFD_WP)) 1047 pmd = pmd_clear_uffd_wp(pmd); 1048 1049 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1050 if (unlikely(is_swap_pmd(pmd))) { 1051 swp_entry_t entry = pmd_to_swp_entry(pmd); 1052 1053 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1054 if (is_write_migration_entry(entry)) { 1055 make_migration_entry_read(&entry); 1056 pmd = swp_entry_to_pmd(entry); 1057 if (pmd_swp_soft_dirty(*src_pmd)) 1058 pmd = pmd_swp_mksoft_dirty(pmd); 1059 set_pmd_at(src_mm, addr, src_pmd, pmd); 1060 } 1061 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1062 mm_inc_nr_ptes(dst_mm); 1063 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1064 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1065 ret = 0; 1066 goto out_unlock; 1067 } 1068 #endif 1069 1070 if (unlikely(!pmd_trans_huge(pmd))) { 1071 pte_free(dst_mm, pgtable); 1072 goto out_unlock; 1073 } 1074 /* 1075 * When page table lock is held, the huge zero pmd should not be 1076 * under splitting since we don't split the page itself, only pmd to 1077 * a page table. 1078 */ 1079 if (is_huge_zero_pmd(pmd)) { 1080 struct page *zero_page; 1081 /* 1082 * get_huge_zero_page() will never allocate a new page here, 1083 * since we already have a zero page to copy. It just takes a 1084 * reference. 1085 */ 1086 zero_page = mm_get_huge_zero_page(dst_mm); 1087 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, 1088 zero_page); 1089 ret = 0; 1090 goto out_unlock; 1091 } 1092 1093 src_page = pmd_page(pmd); 1094 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1095 1096 /* 1097 * If this page is a potentially pinned page, split and retry the fault 1098 * with smaller page size. Normally this should not happen because the 1099 * userspace should use MADV_DONTFORK upon pinned regions. This is a 1100 * best effort that the pinned pages won't be replaced by another 1101 * random page during the coming copy-on-write. 1102 */ 1103 if (unlikely(is_cow_mapping(vma->vm_flags) && 1104 atomic_read(&src_mm->has_pinned) && 1105 page_maybe_dma_pinned(src_page))) { 1106 pte_free(dst_mm, pgtable); 1107 spin_unlock(src_ptl); 1108 spin_unlock(dst_ptl); 1109 __split_huge_pmd(vma, src_pmd, addr, false, NULL); 1110 return -EAGAIN; 1111 } 1112 1113 get_page(src_page); 1114 page_dup_rmap(src_page, true); 1115 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1116 mm_inc_nr_ptes(dst_mm); 1117 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1118 1119 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1120 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1121 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1122 1123 ret = 0; 1124 out_unlock: 1125 spin_unlock(src_ptl); 1126 spin_unlock(dst_ptl); 1127 out: 1128 return ret; 1129 } 1130 1131 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1132 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1133 pud_t *pud, int flags) 1134 { 1135 pud_t _pud; 1136 1137 _pud = pud_mkyoung(*pud); 1138 if (flags & FOLL_WRITE) 1139 _pud = pud_mkdirty(_pud); 1140 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1141 pud, _pud, flags & FOLL_WRITE)) 1142 update_mmu_cache_pud(vma, addr, pud); 1143 } 1144 1145 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1146 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1147 { 1148 unsigned long pfn = pud_pfn(*pud); 1149 struct mm_struct *mm = vma->vm_mm; 1150 struct page *page; 1151 1152 assert_spin_locked(pud_lockptr(mm, pud)); 1153 1154 if (flags & FOLL_WRITE && !pud_write(*pud)) 1155 return NULL; 1156 1157 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1158 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1159 (FOLL_PIN | FOLL_GET))) 1160 return NULL; 1161 1162 if (pud_present(*pud) && pud_devmap(*pud)) 1163 /* pass */; 1164 else 1165 return NULL; 1166 1167 if (flags & FOLL_TOUCH) 1168 touch_pud(vma, addr, pud, flags); 1169 1170 /* 1171 * device mapped pages can only be returned if the 1172 * caller will manage the page reference count. 1173 * 1174 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here: 1175 */ 1176 if (!(flags & (FOLL_GET | FOLL_PIN))) 1177 return ERR_PTR(-EEXIST); 1178 1179 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1180 *pgmap = get_dev_pagemap(pfn, *pgmap); 1181 if (!*pgmap) 1182 return ERR_PTR(-EFAULT); 1183 page = pfn_to_page(pfn); 1184 if (!try_grab_page(page, flags)) 1185 page = ERR_PTR(-ENOMEM); 1186 1187 return page; 1188 } 1189 1190 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1191 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1192 struct vm_area_struct *vma) 1193 { 1194 spinlock_t *dst_ptl, *src_ptl; 1195 pud_t pud; 1196 int ret; 1197 1198 dst_ptl = pud_lock(dst_mm, dst_pud); 1199 src_ptl = pud_lockptr(src_mm, src_pud); 1200 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1201 1202 ret = -EAGAIN; 1203 pud = *src_pud; 1204 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1205 goto out_unlock; 1206 1207 /* 1208 * When page table lock is held, the huge zero pud should not be 1209 * under splitting since we don't split the page itself, only pud to 1210 * a page table. 1211 */ 1212 if (is_huge_zero_pud(pud)) { 1213 /* No huge zero pud yet */ 1214 } 1215 1216 /* Please refer to comments in copy_huge_pmd() */ 1217 if (unlikely(is_cow_mapping(vma->vm_flags) && 1218 atomic_read(&src_mm->has_pinned) && 1219 page_maybe_dma_pinned(pud_page(pud)))) { 1220 spin_unlock(src_ptl); 1221 spin_unlock(dst_ptl); 1222 __split_huge_pud(vma, src_pud, addr); 1223 return -EAGAIN; 1224 } 1225 1226 pudp_set_wrprotect(src_mm, addr, src_pud); 1227 pud = pud_mkold(pud_wrprotect(pud)); 1228 set_pud_at(dst_mm, addr, dst_pud, pud); 1229 1230 ret = 0; 1231 out_unlock: 1232 spin_unlock(src_ptl); 1233 spin_unlock(dst_ptl); 1234 return ret; 1235 } 1236 1237 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1238 { 1239 pud_t entry; 1240 unsigned long haddr; 1241 bool write = vmf->flags & FAULT_FLAG_WRITE; 1242 1243 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1244 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1245 goto unlock; 1246 1247 entry = pud_mkyoung(orig_pud); 1248 if (write) 1249 entry = pud_mkdirty(entry); 1250 haddr = vmf->address & HPAGE_PUD_MASK; 1251 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) 1252 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); 1253 1254 unlock: 1255 spin_unlock(vmf->ptl); 1256 } 1257 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1258 1259 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd) 1260 { 1261 pmd_t entry; 1262 unsigned long haddr; 1263 bool write = vmf->flags & FAULT_FLAG_WRITE; 1264 1265 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1266 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1267 goto unlock; 1268 1269 entry = pmd_mkyoung(orig_pmd); 1270 if (write) 1271 entry = pmd_mkdirty(entry); 1272 haddr = vmf->address & HPAGE_PMD_MASK; 1273 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) 1274 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); 1275 1276 unlock: 1277 spin_unlock(vmf->ptl); 1278 } 1279 1280 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) 1281 { 1282 struct vm_area_struct *vma = vmf->vma; 1283 struct page *page; 1284 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1285 1286 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1287 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1288 1289 if (is_huge_zero_pmd(orig_pmd)) 1290 goto fallback; 1291 1292 spin_lock(vmf->ptl); 1293 1294 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1295 spin_unlock(vmf->ptl); 1296 return 0; 1297 } 1298 1299 page = pmd_page(orig_pmd); 1300 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); 1301 1302 /* Lock page for reuse_swap_page() */ 1303 if (!trylock_page(page)) { 1304 get_page(page); 1305 spin_unlock(vmf->ptl); 1306 lock_page(page); 1307 spin_lock(vmf->ptl); 1308 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1309 spin_unlock(vmf->ptl); 1310 unlock_page(page); 1311 put_page(page); 1312 return 0; 1313 } 1314 put_page(page); 1315 } 1316 1317 /* 1318 * We can only reuse the page if nobody else maps the huge page or it's 1319 * part. 1320 */ 1321 if (reuse_swap_page(page, NULL)) { 1322 pmd_t entry; 1323 entry = pmd_mkyoung(orig_pmd); 1324 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1325 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1326 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1327 unlock_page(page); 1328 spin_unlock(vmf->ptl); 1329 return VM_FAULT_WRITE; 1330 } 1331 1332 unlock_page(page); 1333 spin_unlock(vmf->ptl); 1334 fallback: 1335 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1336 return VM_FAULT_FALLBACK; 1337 } 1338 1339 /* 1340 * FOLL_FORCE can write to even unwritable pmd's, but only 1341 * after we've gone through a COW cycle and they are dirty. 1342 */ 1343 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) 1344 { 1345 return pmd_write(pmd) || 1346 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); 1347 } 1348 1349 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1350 unsigned long addr, 1351 pmd_t *pmd, 1352 unsigned int flags) 1353 { 1354 struct mm_struct *mm = vma->vm_mm; 1355 struct page *page = NULL; 1356 1357 assert_spin_locked(pmd_lockptr(mm, pmd)); 1358 1359 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) 1360 goto out; 1361 1362 /* Avoid dumping huge zero page */ 1363 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1364 return ERR_PTR(-EFAULT); 1365 1366 /* Full NUMA hinting faults to serialise migration in fault paths */ 1367 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) 1368 goto out; 1369 1370 page = pmd_page(*pmd); 1371 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1372 1373 if (!try_grab_page(page, flags)) 1374 return ERR_PTR(-ENOMEM); 1375 1376 if (flags & FOLL_TOUCH) 1377 touch_pmd(vma, addr, pmd, flags); 1378 1379 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { 1380 /* 1381 * We don't mlock() pte-mapped THPs. This way we can avoid 1382 * leaking mlocked pages into non-VM_LOCKED VMAs. 1383 * 1384 * For anon THP: 1385 * 1386 * In most cases the pmd is the only mapping of the page as we 1387 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for 1388 * writable private mappings in populate_vma_page_range(). 1389 * 1390 * The only scenario when we have the page shared here is if we 1391 * mlocking read-only mapping shared over fork(). We skip 1392 * mlocking such pages. 1393 * 1394 * For file THP: 1395 * 1396 * We can expect PageDoubleMap() to be stable under page lock: 1397 * for file pages we set it in page_add_file_rmap(), which 1398 * requires page to be locked. 1399 */ 1400 1401 if (PageAnon(page) && compound_mapcount(page) != 1) 1402 goto skip_mlock; 1403 if (PageDoubleMap(page) || !page->mapping) 1404 goto skip_mlock; 1405 if (!trylock_page(page)) 1406 goto skip_mlock; 1407 if (page->mapping && !PageDoubleMap(page)) 1408 mlock_vma_page(page); 1409 unlock_page(page); 1410 } 1411 skip_mlock: 1412 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1413 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1414 1415 out: 1416 return page; 1417 } 1418 1419 /* NUMA hinting page fault entry point for trans huge pmds */ 1420 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) 1421 { 1422 struct vm_area_struct *vma = vmf->vma; 1423 struct anon_vma *anon_vma = NULL; 1424 struct page *page; 1425 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1426 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id(); 1427 int target_nid, last_cpupid = -1; 1428 bool page_locked; 1429 bool migrated = false; 1430 bool was_writable; 1431 int flags = 0; 1432 1433 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1434 if (unlikely(!pmd_same(pmd, *vmf->pmd))) 1435 goto out_unlock; 1436 1437 /* 1438 * If there are potential migrations, wait for completion and retry 1439 * without disrupting NUMA hinting information. Do not relock and 1440 * check_same as the page may no longer be mapped. 1441 */ 1442 if (unlikely(pmd_trans_migrating(*vmf->pmd))) { 1443 page = pmd_page(*vmf->pmd); 1444 if (!get_page_unless_zero(page)) 1445 goto out_unlock; 1446 spin_unlock(vmf->ptl); 1447 put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE); 1448 goto out; 1449 } 1450 1451 page = pmd_page(pmd); 1452 BUG_ON(is_huge_zero_page(page)); 1453 page_nid = page_to_nid(page); 1454 last_cpupid = page_cpupid_last(page); 1455 count_vm_numa_event(NUMA_HINT_FAULTS); 1456 if (page_nid == this_nid) { 1457 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 1458 flags |= TNF_FAULT_LOCAL; 1459 } 1460 1461 /* See similar comment in do_numa_page for explanation */ 1462 if (!pmd_savedwrite(pmd)) 1463 flags |= TNF_NO_GROUP; 1464 1465 /* 1466 * Acquire the page lock to serialise THP migrations but avoid dropping 1467 * page_table_lock if at all possible 1468 */ 1469 page_locked = trylock_page(page); 1470 target_nid = mpol_misplaced(page, vma, haddr); 1471 if (target_nid == NUMA_NO_NODE) { 1472 /* If the page was locked, there are no parallel migrations */ 1473 if (page_locked) 1474 goto clear_pmdnuma; 1475 } 1476 1477 /* Migration could have started since the pmd_trans_migrating check */ 1478 if (!page_locked) { 1479 page_nid = NUMA_NO_NODE; 1480 if (!get_page_unless_zero(page)) 1481 goto out_unlock; 1482 spin_unlock(vmf->ptl); 1483 put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE); 1484 goto out; 1485 } 1486 1487 /* 1488 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma 1489 * to serialises splits 1490 */ 1491 get_page(page); 1492 spin_unlock(vmf->ptl); 1493 anon_vma = page_lock_anon_vma_read(page); 1494 1495 /* Confirm the PMD did not change while page_table_lock was released */ 1496 spin_lock(vmf->ptl); 1497 if (unlikely(!pmd_same(pmd, *vmf->pmd))) { 1498 unlock_page(page); 1499 put_page(page); 1500 page_nid = NUMA_NO_NODE; 1501 goto out_unlock; 1502 } 1503 1504 /* Bail if we fail to protect against THP splits for any reason */ 1505 if (unlikely(!anon_vma)) { 1506 put_page(page); 1507 page_nid = NUMA_NO_NODE; 1508 goto clear_pmdnuma; 1509 } 1510 1511 /* 1512 * Since we took the NUMA fault, we must have observed the !accessible 1513 * bit. Make sure all other CPUs agree with that, to avoid them 1514 * modifying the page we're about to migrate. 1515 * 1516 * Must be done under PTL such that we'll observe the relevant 1517 * inc_tlb_flush_pending(). 1518 * 1519 * We are not sure a pending tlb flush here is for a huge page 1520 * mapping or not. Hence use the tlb range variant 1521 */ 1522 if (mm_tlb_flush_pending(vma->vm_mm)) { 1523 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE); 1524 /* 1525 * change_huge_pmd() released the pmd lock before 1526 * invalidating the secondary MMUs sharing the primary 1527 * MMU pagetables (with ->invalidate_range()). The 1528 * mmu_notifier_invalidate_range_end() (which 1529 * internally calls ->invalidate_range()) in 1530 * change_pmd_range() will run after us, so we can't 1531 * rely on it here and we need an explicit invalidate. 1532 */ 1533 mmu_notifier_invalidate_range(vma->vm_mm, haddr, 1534 haddr + HPAGE_PMD_SIZE); 1535 } 1536 1537 /* 1538 * Migrate the THP to the requested node, returns with page unlocked 1539 * and access rights restored. 1540 */ 1541 spin_unlock(vmf->ptl); 1542 1543 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma, 1544 vmf->pmd, pmd, vmf->address, page, target_nid); 1545 if (migrated) { 1546 flags |= TNF_MIGRATED; 1547 page_nid = target_nid; 1548 } else 1549 flags |= TNF_MIGRATE_FAIL; 1550 1551 goto out; 1552 clear_pmdnuma: 1553 BUG_ON(!PageLocked(page)); 1554 was_writable = pmd_savedwrite(pmd); 1555 pmd = pmd_modify(pmd, vma->vm_page_prot); 1556 pmd = pmd_mkyoung(pmd); 1557 if (was_writable) 1558 pmd = pmd_mkwrite(pmd); 1559 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1560 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1561 unlock_page(page); 1562 out_unlock: 1563 spin_unlock(vmf->ptl); 1564 1565 out: 1566 if (anon_vma) 1567 page_unlock_anon_vma_read(anon_vma); 1568 1569 if (page_nid != NUMA_NO_NODE) 1570 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1571 flags); 1572 1573 return 0; 1574 } 1575 1576 /* 1577 * Return true if we do MADV_FREE successfully on entire pmd page. 1578 * Otherwise, return false. 1579 */ 1580 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1581 pmd_t *pmd, unsigned long addr, unsigned long next) 1582 { 1583 spinlock_t *ptl; 1584 pmd_t orig_pmd; 1585 struct page *page; 1586 struct mm_struct *mm = tlb->mm; 1587 bool ret = false; 1588 1589 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1590 1591 ptl = pmd_trans_huge_lock(pmd, vma); 1592 if (!ptl) 1593 goto out_unlocked; 1594 1595 orig_pmd = *pmd; 1596 if (is_huge_zero_pmd(orig_pmd)) 1597 goto out; 1598 1599 if (unlikely(!pmd_present(orig_pmd))) { 1600 VM_BUG_ON(thp_migration_supported() && 1601 !is_pmd_migration_entry(orig_pmd)); 1602 goto out; 1603 } 1604 1605 page = pmd_page(orig_pmd); 1606 /* 1607 * If other processes are mapping this page, we couldn't discard 1608 * the page unless they all do MADV_FREE so let's skip the page. 1609 */ 1610 if (page_mapcount(page) != 1) 1611 goto out; 1612 1613 if (!trylock_page(page)) 1614 goto out; 1615 1616 /* 1617 * If user want to discard part-pages of THP, split it so MADV_FREE 1618 * will deactivate only them. 1619 */ 1620 if (next - addr != HPAGE_PMD_SIZE) { 1621 get_page(page); 1622 spin_unlock(ptl); 1623 split_huge_page(page); 1624 unlock_page(page); 1625 put_page(page); 1626 goto out_unlocked; 1627 } 1628 1629 if (PageDirty(page)) 1630 ClearPageDirty(page); 1631 unlock_page(page); 1632 1633 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1634 pmdp_invalidate(vma, addr, pmd); 1635 orig_pmd = pmd_mkold(orig_pmd); 1636 orig_pmd = pmd_mkclean(orig_pmd); 1637 1638 set_pmd_at(mm, addr, pmd, orig_pmd); 1639 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1640 } 1641 1642 mark_page_lazyfree(page); 1643 ret = true; 1644 out: 1645 spin_unlock(ptl); 1646 out_unlocked: 1647 return ret; 1648 } 1649 1650 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1651 { 1652 pgtable_t pgtable; 1653 1654 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1655 pte_free(mm, pgtable); 1656 mm_dec_nr_ptes(mm); 1657 } 1658 1659 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1660 pmd_t *pmd, unsigned long addr) 1661 { 1662 pmd_t orig_pmd; 1663 spinlock_t *ptl; 1664 1665 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1666 1667 ptl = __pmd_trans_huge_lock(pmd, vma); 1668 if (!ptl) 1669 return 0; 1670 /* 1671 * For architectures like ppc64 we look at deposited pgtable 1672 * when calling pmdp_huge_get_and_clear. So do the 1673 * pgtable_trans_huge_withdraw after finishing pmdp related 1674 * operations. 1675 */ 1676 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1677 tlb->fullmm); 1678 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1679 if (vma_is_special_huge(vma)) { 1680 if (arch_needs_pgtable_deposit()) 1681 zap_deposited_table(tlb->mm, pmd); 1682 spin_unlock(ptl); 1683 if (is_huge_zero_pmd(orig_pmd)) 1684 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1685 } else if (is_huge_zero_pmd(orig_pmd)) { 1686 zap_deposited_table(tlb->mm, pmd); 1687 spin_unlock(ptl); 1688 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1689 } else { 1690 struct page *page = NULL; 1691 int flush_needed = 1; 1692 1693 if (pmd_present(orig_pmd)) { 1694 page = pmd_page(orig_pmd); 1695 page_remove_rmap(page, true); 1696 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1697 VM_BUG_ON_PAGE(!PageHead(page), page); 1698 } else if (thp_migration_supported()) { 1699 swp_entry_t entry; 1700 1701 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1702 entry = pmd_to_swp_entry(orig_pmd); 1703 page = pfn_to_page(swp_offset(entry)); 1704 flush_needed = 0; 1705 } else 1706 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1707 1708 if (PageAnon(page)) { 1709 zap_deposited_table(tlb->mm, pmd); 1710 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1711 } else { 1712 if (arch_needs_pgtable_deposit()) 1713 zap_deposited_table(tlb->mm, pmd); 1714 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1715 } 1716 1717 spin_unlock(ptl); 1718 if (flush_needed) 1719 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1720 } 1721 return 1; 1722 } 1723 1724 #ifndef pmd_move_must_withdraw 1725 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1726 spinlock_t *old_pmd_ptl, 1727 struct vm_area_struct *vma) 1728 { 1729 /* 1730 * With split pmd lock we also need to move preallocated 1731 * PTE page table if new_pmd is on different PMD page table. 1732 * 1733 * We also don't deposit and withdraw tables for file pages. 1734 */ 1735 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1736 } 1737 #endif 1738 1739 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1740 { 1741 #ifdef CONFIG_MEM_SOFT_DIRTY 1742 if (unlikely(is_pmd_migration_entry(pmd))) 1743 pmd = pmd_swp_mksoft_dirty(pmd); 1744 else if (pmd_present(pmd)) 1745 pmd = pmd_mksoft_dirty(pmd); 1746 #endif 1747 return pmd; 1748 } 1749 1750 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1751 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1752 { 1753 spinlock_t *old_ptl, *new_ptl; 1754 pmd_t pmd; 1755 struct mm_struct *mm = vma->vm_mm; 1756 bool force_flush = false; 1757 1758 /* 1759 * The destination pmd shouldn't be established, free_pgtables() 1760 * should have release it. 1761 */ 1762 if (WARN_ON(!pmd_none(*new_pmd))) { 1763 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1764 return false; 1765 } 1766 1767 /* 1768 * We don't have to worry about the ordering of src and dst 1769 * ptlocks because exclusive mmap_lock prevents deadlock. 1770 */ 1771 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1772 if (old_ptl) { 1773 new_ptl = pmd_lockptr(mm, new_pmd); 1774 if (new_ptl != old_ptl) 1775 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1776 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1777 if (pmd_present(pmd)) 1778 force_flush = true; 1779 VM_BUG_ON(!pmd_none(*new_pmd)); 1780 1781 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1782 pgtable_t pgtable; 1783 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1784 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1785 } 1786 pmd = move_soft_dirty_pmd(pmd); 1787 set_pmd_at(mm, new_addr, new_pmd, pmd); 1788 if (force_flush) 1789 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1790 if (new_ptl != old_ptl) 1791 spin_unlock(new_ptl); 1792 spin_unlock(old_ptl); 1793 return true; 1794 } 1795 return false; 1796 } 1797 1798 /* 1799 * Returns 1800 * - 0 if PMD could not be locked 1801 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary 1802 * - HPAGE_PMD_NR is protections changed and TLB flush necessary 1803 */ 1804 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 1805 unsigned long addr, pgprot_t newprot, unsigned long cp_flags) 1806 { 1807 struct mm_struct *mm = vma->vm_mm; 1808 spinlock_t *ptl; 1809 pmd_t entry; 1810 bool preserve_write; 1811 int ret; 1812 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1813 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1814 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1815 1816 ptl = __pmd_trans_huge_lock(pmd, vma); 1817 if (!ptl) 1818 return 0; 1819 1820 preserve_write = prot_numa && pmd_write(*pmd); 1821 ret = 1; 1822 1823 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1824 if (is_swap_pmd(*pmd)) { 1825 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1826 1827 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1828 if (is_write_migration_entry(entry)) { 1829 pmd_t newpmd; 1830 /* 1831 * A protection check is difficult so 1832 * just be safe and disable write 1833 */ 1834 make_migration_entry_read(&entry); 1835 newpmd = swp_entry_to_pmd(entry); 1836 if (pmd_swp_soft_dirty(*pmd)) 1837 newpmd = pmd_swp_mksoft_dirty(newpmd); 1838 set_pmd_at(mm, addr, pmd, newpmd); 1839 } 1840 goto unlock; 1841 } 1842 #endif 1843 1844 /* 1845 * Avoid trapping faults against the zero page. The read-only 1846 * data is likely to be read-cached on the local CPU and 1847 * local/remote hits to the zero page are not interesting. 1848 */ 1849 if (prot_numa && is_huge_zero_pmd(*pmd)) 1850 goto unlock; 1851 1852 if (prot_numa && pmd_protnone(*pmd)) 1853 goto unlock; 1854 1855 /* 1856 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 1857 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1858 * which is also under mmap_read_lock(mm): 1859 * 1860 * CPU0: CPU1: 1861 * change_huge_pmd(prot_numa=1) 1862 * pmdp_huge_get_and_clear_notify() 1863 * madvise_dontneed() 1864 * zap_pmd_range() 1865 * pmd_trans_huge(*pmd) == 0 (without ptl) 1866 * // skip the pmd 1867 * set_pmd_at(); 1868 * // pmd is re-established 1869 * 1870 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1871 * which may break userspace. 1872 * 1873 * pmdp_invalidate() is required to make sure we don't miss 1874 * dirty/young flags set by hardware. 1875 */ 1876 entry = pmdp_invalidate(vma, addr, pmd); 1877 1878 entry = pmd_modify(entry, newprot); 1879 if (preserve_write) 1880 entry = pmd_mk_savedwrite(entry); 1881 if (uffd_wp) { 1882 entry = pmd_wrprotect(entry); 1883 entry = pmd_mkuffd_wp(entry); 1884 } else if (uffd_wp_resolve) { 1885 /* 1886 * Leave the write bit to be handled by PF interrupt 1887 * handler, then things like COW could be properly 1888 * handled. 1889 */ 1890 entry = pmd_clear_uffd_wp(entry); 1891 } 1892 ret = HPAGE_PMD_NR; 1893 set_pmd_at(mm, addr, pmd, entry); 1894 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); 1895 unlock: 1896 spin_unlock(ptl); 1897 return ret; 1898 } 1899 1900 /* 1901 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1902 * 1903 * Note that if it returns page table lock pointer, this routine returns without 1904 * unlocking page table lock. So callers must unlock it. 1905 */ 1906 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1907 { 1908 spinlock_t *ptl; 1909 ptl = pmd_lock(vma->vm_mm, pmd); 1910 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 1911 pmd_devmap(*pmd))) 1912 return ptl; 1913 spin_unlock(ptl); 1914 return NULL; 1915 } 1916 1917 /* 1918 * Returns true if a given pud maps a thp, false otherwise. 1919 * 1920 * Note that if it returns true, this routine returns without unlocking page 1921 * table lock. So callers must unlock it. 1922 */ 1923 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 1924 { 1925 spinlock_t *ptl; 1926 1927 ptl = pud_lock(vma->vm_mm, pud); 1928 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 1929 return ptl; 1930 spin_unlock(ptl); 1931 return NULL; 1932 } 1933 1934 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1935 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 1936 pud_t *pud, unsigned long addr) 1937 { 1938 spinlock_t *ptl; 1939 1940 ptl = __pud_trans_huge_lock(pud, vma); 1941 if (!ptl) 1942 return 0; 1943 /* 1944 * For architectures like ppc64 we look at deposited pgtable 1945 * when calling pudp_huge_get_and_clear. So do the 1946 * pgtable_trans_huge_withdraw after finishing pudp related 1947 * operations. 1948 */ 1949 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 1950 tlb_remove_pud_tlb_entry(tlb, pud, addr); 1951 if (vma_is_special_huge(vma)) { 1952 spin_unlock(ptl); 1953 /* No zero page support yet */ 1954 } else { 1955 /* No support for anonymous PUD pages yet */ 1956 BUG(); 1957 } 1958 return 1; 1959 } 1960 1961 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 1962 unsigned long haddr) 1963 { 1964 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 1965 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 1966 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 1967 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 1968 1969 count_vm_event(THP_SPLIT_PUD); 1970 1971 pudp_huge_clear_flush_notify(vma, haddr, pud); 1972 } 1973 1974 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 1975 unsigned long address) 1976 { 1977 spinlock_t *ptl; 1978 struct mmu_notifier_range range; 1979 1980 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1981 address & HPAGE_PUD_MASK, 1982 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 1983 mmu_notifier_invalidate_range_start(&range); 1984 ptl = pud_lock(vma->vm_mm, pud); 1985 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 1986 goto out; 1987 __split_huge_pud_locked(vma, pud, range.start); 1988 1989 out: 1990 spin_unlock(ptl); 1991 /* 1992 * No need to double call mmu_notifier->invalidate_range() callback as 1993 * the above pudp_huge_clear_flush_notify() did already call it. 1994 */ 1995 mmu_notifier_invalidate_range_only_end(&range); 1996 } 1997 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1998 1999 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2000 unsigned long haddr, pmd_t *pmd) 2001 { 2002 struct mm_struct *mm = vma->vm_mm; 2003 pgtable_t pgtable; 2004 pmd_t _pmd; 2005 int i; 2006 2007 /* 2008 * Leave pmd empty until pte is filled note that it is fine to delay 2009 * notification until mmu_notifier_invalidate_range_end() as we are 2010 * replacing a zero pmd write protected page with a zero pte write 2011 * protected page. 2012 * 2013 * See Documentation/vm/mmu_notifier.rst 2014 */ 2015 pmdp_huge_clear_flush(vma, haddr, pmd); 2016 2017 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2018 pmd_populate(mm, &_pmd, pgtable); 2019 2020 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 2021 pte_t *pte, entry; 2022 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 2023 entry = pte_mkspecial(entry); 2024 pte = pte_offset_map(&_pmd, haddr); 2025 VM_BUG_ON(!pte_none(*pte)); 2026 set_pte_at(mm, haddr, pte, entry); 2027 pte_unmap(pte); 2028 } 2029 smp_wmb(); /* make pte visible before pmd */ 2030 pmd_populate(mm, pmd, pgtable); 2031 } 2032 2033 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2034 unsigned long haddr, bool freeze) 2035 { 2036 struct mm_struct *mm = vma->vm_mm; 2037 struct page *page; 2038 pgtable_t pgtable; 2039 pmd_t old_pmd, _pmd; 2040 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 2041 unsigned long addr; 2042 int i; 2043 2044 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2045 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2046 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2047 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2048 && !pmd_devmap(*pmd)); 2049 2050 count_vm_event(THP_SPLIT_PMD); 2051 2052 if (!vma_is_anonymous(vma)) { 2053 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 2054 /* 2055 * We are going to unmap this huge page. So 2056 * just go ahead and zap it 2057 */ 2058 if (arch_needs_pgtable_deposit()) 2059 zap_deposited_table(mm, pmd); 2060 if (vma_is_special_huge(vma)) 2061 return; 2062 page = pmd_page(_pmd); 2063 if (!PageDirty(page) && pmd_dirty(_pmd)) 2064 set_page_dirty(page); 2065 if (!PageReferenced(page) && pmd_young(_pmd)) 2066 SetPageReferenced(page); 2067 page_remove_rmap(page, true); 2068 put_page(page); 2069 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2070 return; 2071 } else if (pmd_trans_huge(*pmd) && is_huge_zero_pmd(*pmd)) { 2072 /* 2073 * FIXME: Do we want to invalidate secondary mmu by calling 2074 * mmu_notifier_invalidate_range() see comments below inside 2075 * __split_huge_pmd() ? 2076 * 2077 * We are going from a zero huge page write protected to zero 2078 * small page also write protected so it does not seems useful 2079 * to invalidate secondary mmu at this time. 2080 */ 2081 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2082 } 2083 2084 /* 2085 * Up to this point the pmd is present and huge and userland has the 2086 * whole access to the hugepage during the split (which happens in 2087 * place). If we overwrite the pmd with the not-huge version pointing 2088 * to the pte here (which of course we could if all CPUs were bug 2089 * free), userland could trigger a small page size TLB miss on the 2090 * small sized TLB while the hugepage TLB entry is still established in 2091 * the huge TLB. Some CPU doesn't like that. 2092 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2093 * 383 on page 105. Intel should be safe but is also warns that it's 2094 * only safe if the permission and cache attributes of the two entries 2095 * loaded in the two TLB is identical (which should be the case here). 2096 * But it is generally safer to never allow small and huge TLB entries 2097 * for the same virtual address to be loaded simultaneously. So instead 2098 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2099 * current pmd notpresent (atomically because here the pmd_trans_huge 2100 * must remain set at all times on the pmd until the split is complete 2101 * for this pmd), then we flush the SMP TLB and finally we write the 2102 * non-huge version of the pmd entry with pmd_populate. 2103 */ 2104 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2105 2106 pmd_migration = is_pmd_migration_entry(old_pmd); 2107 if (unlikely(pmd_migration)) { 2108 swp_entry_t entry; 2109 2110 entry = pmd_to_swp_entry(old_pmd); 2111 page = pfn_to_page(swp_offset(entry)); 2112 write = is_write_migration_entry(entry); 2113 young = false; 2114 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2115 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2116 } else { 2117 page = pmd_page(old_pmd); 2118 if (pmd_dirty(old_pmd)) 2119 SetPageDirty(page); 2120 write = pmd_write(old_pmd); 2121 young = pmd_young(old_pmd); 2122 soft_dirty = pmd_soft_dirty(old_pmd); 2123 uffd_wp = pmd_uffd_wp(old_pmd); 2124 } 2125 VM_BUG_ON_PAGE(!page_count(page), page); 2126 page_ref_add(page, HPAGE_PMD_NR - 1); 2127 2128 /* 2129 * Withdraw the table only after we mark the pmd entry invalid. 2130 * This's critical for some architectures (Power). 2131 */ 2132 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2133 pmd_populate(mm, &_pmd, pgtable); 2134 2135 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2136 pte_t entry, *pte; 2137 /* 2138 * Note that NUMA hinting access restrictions are not 2139 * transferred to avoid any possibility of altering 2140 * permissions across VMAs. 2141 */ 2142 if (freeze || pmd_migration) { 2143 swp_entry_t swp_entry; 2144 swp_entry = make_migration_entry(page + i, write); 2145 entry = swp_entry_to_pte(swp_entry); 2146 if (soft_dirty) 2147 entry = pte_swp_mksoft_dirty(entry); 2148 if (uffd_wp) 2149 entry = pte_swp_mkuffd_wp(entry); 2150 } else { 2151 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2152 entry = maybe_mkwrite(entry, vma); 2153 if (!write) 2154 entry = pte_wrprotect(entry); 2155 if (!young) 2156 entry = pte_mkold(entry); 2157 if (soft_dirty) 2158 entry = pte_mksoft_dirty(entry); 2159 if (uffd_wp) 2160 entry = pte_mkuffd_wp(entry); 2161 } 2162 pte = pte_offset_map(&_pmd, addr); 2163 BUG_ON(!pte_none(*pte)); 2164 set_pte_at(mm, addr, pte, entry); 2165 if (!pmd_migration) 2166 atomic_inc(&page[i]._mapcount); 2167 pte_unmap(pte); 2168 } 2169 2170 if (!pmd_migration) { 2171 /* 2172 * Set PG_double_map before dropping compound_mapcount to avoid 2173 * false-negative page_mapped(). 2174 */ 2175 if (compound_mapcount(page) > 1 && 2176 !TestSetPageDoubleMap(page)) { 2177 for (i = 0; i < HPAGE_PMD_NR; i++) 2178 atomic_inc(&page[i]._mapcount); 2179 } 2180 2181 lock_page_memcg(page); 2182 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { 2183 /* Last compound_mapcount is gone. */ 2184 __mod_lruvec_page_state(page, NR_ANON_THPS, 2185 -HPAGE_PMD_NR); 2186 if (TestClearPageDoubleMap(page)) { 2187 /* No need in mapcount reference anymore */ 2188 for (i = 0; i < HPAGE_PMD_NR; i++) 2189 atomic_dec(&page[i]._mapcount); 2190 } 2191 } 2192 unlock_page_memcg(page); 2193 } 2194 2195 smp_wmb(); /* make pte visible before pmd */ 2196 pmd_populate(mm, pmd, pgtable); 2197 2198 if (freeze) { 2199 for (i = 0; i < HPAGE_PMD_NR; i++) { 2200 page_remove_rmap(page + i, false); 2201 put_page(page + i); 2202 } 2203 } 2204 } 2205 2206 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2207 unsigned long address, bool freeze, struct page *page) 2208 { 2209 spinlock_t *ptl; 2210 struct mmu_notifier_range range; 2211 bool do_unlock_page = false; 2212 pmd_t _pmd; 2213 2214 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2215 address & HPAGE_PMD_MASK, 2216 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2217 mmu_notifier_invalidate_range_start(&range); 2218 ptl = pmd_lock(vma->vm_mm, pmd); 2219 2220 /* 2221 * If caller asks to setup a migration entries, we need a page to check 2222 * pmd against. Otherwise we can end up replacing wrong page. 2223 */ 2224 VM_BUG_ON(freeze && !page); 2225 if (page) { 2226 VM_WARN_ON_ONCE(!PageLocked(page)); 2227 if (page != pmd_page(*pmd)) 2228 goto out; 2229 } 2230 2231 repeat: 2232 if (pmd_trans_huge(*pmd)) { 2233 if (!page) { 2234 page = pmd_page(*pmd); 2235 /* 2236 * An anonymous page must be locked, to ensure that a 2237 * concurrent reuse_swap_page() sees stable mapcount; 2238 * but reuse_swap_page() is not used on shmem or file, 2239 * and page lock must not be taken when zap_pmd_range() 2240 * calls __split_huge_pmd() while i_mmap_lock is held. 2241 */ 2242 if (PageAnon(page)) { 2243 if (unlikely(!trylock_page(page))) { 2244 get_page(page); 2245 _pmd = *pmd; 2246 spin_unlock(ptl); 2247 lock_page(page); 2248 spin_lock(ptl); 2249 if (unlikely(!pmd_same(*pmd, _pmd))) { 2250 unlock_page(page); 2251 put_page(page); 2252 page = NULL; 2253 goto repeat; 2254 } 2255 put_page(page); 2256 } 2257 do_unlock_page = true; 2258 } 2259 } 2260 if (PageMlocked(page)) 2261 clear_page_mlock(page); 2262 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd))) 2263 goto out; 2264 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2265 out: 2266 spin_unlock(ptl); 2267 if (do_unlock_page) 2268 unlock_page(page); 2269 /* 2270 * No need to double call mmu_notifier->invalidate_range() callback. 2271 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2272 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2273 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2274 * fault will trigger a flush_notify before pointing to a new page 2275 * (it is fine if the secondary mmu keeps pointing to the old zero 2276 * page in the meantime) 2277 * 3) Split a huge pmd into pte pointing to the same page. No need 2278 * to invalidate secondary tlb entry they are all still valid. 2279 * any further changes to individual pte will notify. So no need 2280 * to call mmu_notifier->invalidate_range() 2281 */ 2282 mmu_notifier_invalidate_range_only_end(&range); 2283 } 2284 2285 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2286 bool freeze, struct page *page) 2287 { 2288 pgd_t *pgd; 2289 p4d_t *p4d; 2290 pud_t *pud; 2291 pmd_t *pmd; 2292 2293 pgd = pgd_offset(vma->vm_mm, address); 2294 if (!pgd_present(*pgd)) 2295 return; 2296 2297 p4d = p4d_offset(pgd, address); 2298 if (!p4d_present(*p4d)) 2299 return; 2300 2301 pud = pud_offset(p4d, address); 2302 if (!pud_present(*pud)) 2303 return; 2304 2305 pmd = pmd_offset(pud, address); 2306 2307 __split_huge_pmd(vma, pmd, address, freeze, page); 2308 } 2309 2310 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2311 unsigned long start, 2312 unsigned long end, 2313 long adjust_next) 2314 { 2315 /* 2316 * If the new start address isn't hpage aligned and it could 2317 * previously contain an hugepage: check if we need to split 2318 * an huge pmd. 2319 */ 2320 if (start & ~HPAGE_PMD_MASK && 2321 (start & HPAGE_PMD_MASK) >= vma->vm_start && 2322 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2323 split_huge_pmd_address(vma, start, false, NULL); 2324 2325 /* 2326 * If the new end address isn't hpage aligned and it could 2327 * previously contain an hugepage: check if we need to split 2328 * an huge pmd. 2329 */ 2330 if (end & ~HPAGE_PMD_MASK && 2331 (end & HPAGE_PMD_MASK) >= vma->vm_start && 2332 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2333 split_huge_pmd_address(vma, end, false, NULL); 2334 2335 /* 2336 * If we're also updating the vma->vm_next->vm_start, if the new 2337 * vm_next->vm_start isn't hpage aligned and it could previously 2338 * contain an hugepage: check if we need to split an huge pmd. 2339 */ 2340 if (adjust_next > 0) { 2341 struct vm_area_struct *next = vma->vm_next; 2342 unsigned long nstart = next->vm_start; 2343 nstart += adjust_next; 2344 if (nstart & ~HPAGE_PMD_MASK && 2345 (nstart & HPAGE_PMD_MASK) >= next->vm_start && 2346 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) 2347 split_huge_pmd_address(next, nstart, false, NULL); 2348 } 2349 } 2350 2351 static void unmap_page(struct page *page) 2352 { 2353 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | 2354 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD; 2355 bool unmap_success; 2356 2357 VM_BUG_ON_PAGE(!PageHead(page), page); 2358 2359 if (PageAnon(page)) 2360 ttu_flags |= TTU_SPLIT_FREEZE; 2361 2362 unmap_success = try_to_unmap(page, ttu_flags); 2363 VM_BUG_ON_PAGE(!unmap_success, page); 2364 } 2365 2366 static void remap_page(struct page *page, unsigned int nr) 2367 { 2368 int i; 2369 if (PageTransHuge(page)) { 2370 remove_migration_ptes(page, page, true); 2371 } else { 2372 for (i = 0; i < nr; i++) 2373 remove_migration_ptes(page + i, page + i, true); 2374 } 2375 } 2376 2377 static void lru_add_page_tail(struct page *head, struct page *tail, 2378 struct lruvec *lruvec, struct list_head *list) 2379 { 2380 VM_BUG_ON_PAGE(!PageHead(head), head); 2381 VM_BUG_ON_PAGE(PageCompound(tail), head); 2382 VM_BUG_ON_PAGE(PageLRU(tail), head); 2383 lockdep_assert_held(&lruvec->lru_lock); 2384 2385 if (list) { 2386 /* page reclaim is reclaiming a huge page */ 2387 VM_WARN_ON(PageLRU(head)); 2388 get_page(tail); 2389 list_add_tail(&tail->lru, list); 2390 } else { 2391 /* head is still on lru (and we have it frozen) */ 2392 VM_WARN_ON(!PageLRU(head)); 2393 SetPageLRU(tail); 2394 list_add_tail(&tail->lru, &head->lru); 2395 } 2396 } 2397 2398 static void __split_huge_page_tail(struct page *head, int tail, 2399 struct lruvec *lruvec, struct list_head *list) 2400 { 2401 struct page *page_tail = head + tail; 2402 2403 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2404 2405 /* 2406 * Clone page flags before unfreezing refcount. 2407 * 2408 * After successful get_page_unless_zero() might follow flags change, 2409 * for example lock_page() which set PG_waiters. 2410 */ 2411 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2412 page_tail->flags |= (head->flags & 2413 ((1L << PG_referenced) | 2414 (1L << PG_swapbacked) | 2415 (1L << PG_swapcache) | 2416 (1L << PG_mlocked) | 2417 (1L << PG_uptodate) | 2418 (1L << PG_active) | 2419 (1L << PG_workingset) | 2420 (1L << PG_locked) | 2421 (1L << PG_unevictable) | 2422 #ifdef CONFIG_64BIT 2423 (1L << PG_arch_2) | 2424 #endif 2425 (1L << PG_dirty))); 2426 2427 /* ->mapping in first tail page is compound_mapcount */ 2428 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2429 page_tail); 2430 page_tail->mapping = head->mapping; 2431 page_tail->index = head->index + tail; 2432 2433 /* Page flags must be visible before we make the page non-compound. */ 2434 smp_wmb(); 2435 2436 /* 2437 * Clear PageTail before unfreezing page refcount. 2438 * 2439 * After successful get_page_unless_zero() might follow put_page() 2440 * which needs correct compound_head(). 2441 */ 2442 clear_compound_head(page_tail); 2443 2444 /* Finally unfreeze refcount. Additional reference from page cache. */ 2445 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2446 PageSwapCache(head))); 2447 2448 if (page_is_young(head)) 2449 set_page_young(page_tail); 2450 if (page_is_idle(head)) 2451 set_page_idle(page_tail); 2452 2453 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2454 2455 /* 2456 * always add to the tail because some iterators expect new 2457 * pages to show after the currently processed elements - e.g. 2458 * migrate_pages 2459 */ 2460 lru_add_page_tail(head, page_tail, lruvec, list); 2461 } 2462 2463 static void __split_huge_page(struct page *page, struct list_head *list, 2464 pgoff_t end) 2465 { 2466 struct page *head = compound_head(page); 2467 struct lruvec *lruvec; 2468 struct address_space *swap_cache = NULL; 2469 unsigned long offset = 0; 2470 unsigned int nr = thp_nr_pages(head); 2471 int i; 2472 2473 /* complete memcg works before add pages to LRU */ 2474 mem_cgroup_split_huge_fixup(head); 2475 2476 if (PageAnon(head) && PageSwapCache(head)) { 2477 swp_entry_t entry = { .val = page_private(head) }; 2478 2479 offset = swp_offset(entry); 2480 swap_cache = swap_address_space(entry); 2481 xa_lock(&swap_cache->i_pages); 2482 } 2483 2484 /* lock lru list/PageCompound, ref freezed by page_ref_freeze */ 2485 lruvec = lock_page_lruvec(head); 2486 2487 for (i = nr - 1; i >= 1; i--) { 2488 __split_huge_page_tail(head, i, lruvec, list); 2489 /* Some pages can be beyond i_size: drop them from page cache */ 2490 if (head[i].index >= end) { 2491 ClearPageDirty(head + i); 2492 __delete_from_page_cache(head + i, NULL); 2493 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) 2494 shmem_uncharge(head->mapping->host, 1); 2495 put_page(head + i); 2496 } else if (!PageAnon(page)) { 2497 __xa_store(&head->mapping->i_pages, head[i].index, 2498 head + i, 0); 2499 } else if (swap_cache) { 2500 __xa_store(&swap_cache->i_pages, offset + i, 2501 head + i, 0); 2502 } 2503 } 2504 2505 ClearPageCompound(head); 2506 unlock_page_lruvec(lruvec); 2507 /* Caller disabled irqs, so they are still disabled here */ 2508 2509 split_page_owner(head, nr); 2510 2511 /* See comment in __split_huge_page_tail() */ 2512 if (PageAnon(head)) { 2513 /* Additional pin to swap cache */ 2514 if (PageSwapCache(head)) { 2515 page_ref_add(head, 2); 2516 xa_unlock(&swap_cache->i_pages); 2517 } else { 2518 page_ref_inc(head); 2519 } 2520 } else { 2521 /* Additional pin to page cache */ 2522 page_ref_add(head, 2); 2523 xa_unlock(&head->mapping->i_pages); 2524 } 2525 local_irq_enable(); 2526 2527 remap_page(head, nr); 2528 2529 if (PageSwapCache(head)) { 2530 swp_entry_t entry = { .val = page_private(head) }; 2531 2532 split_swap_cluster(entry); 2533 } 2534 2535 for (i = 0; i < nr; i++) { 2536 struct page *subpage = head + i; 2537 if (subpage == page) 2538 continue; 2539 unlock_page(subpage); 2540 2541 /* 2542 * Subpages may be freed if there wasn't any mapping 2543 * like if add_to_swap() is running on a lru page that 2544 * had its mapping zapped. And freeing these pages 2545 * requires taking the lru_lock so we do the put_page 2546 * of the tail pages after the split is complete. 2547 */ 2548 put_page(subpage); 2549 } 2550 } 2551 2552 int total_mapcount(struct page *page) 2553 { 2554 int i, compound, nr, ret; 2555 2556 VM_BUG_ON_PAGE(PageTail(page), page); 2557 2558 if (likely(!PageCompound(page))) 2559 return atomic_read(&page->_mapcount) + 1; 2560 2561 compound = compound_mapcount(page); 2562 nr = compound_nr(page); 2563 if (PageHuge(page)) 2564 return compound; 2565 ret = compound; 2566 for (i = 0; i < nr; i++) 2567 ret += atomic_read(&page[i]._mapcount) + 1; 2568 /* File pages has compound_mapcount included in _mapcount */ 2569 if (!PageAnon(page)) 2570 return ret - compound * nr; 2571 if (PageDoubleMap(page)) 2572 ret -= nr; 2573 return ret; 2574 } 2575 2576 /* 2577 * This calculates accurately how many mappings a transparent hugepage 2578 * has (unlike page_mapcount() which isn't fully accurate). This full 2579 * accuracy is primarily needed to know if copy-on-write faults can 2580 * reuse the page and change the mapping to read-write instead of 2581 * copying them. At the same time this returns the total_mapcount too. 2582 * 2583 * The function returns the highest mapcount any one of the subpages 2584 * has. If the return value is one, even if different processes are 2585 * mapping different subpages of the transparent hugepage, they can 2586 * all reuse it, because each process is reusing a different subpage. 2587 * 2588 * The total_mapcount is instead counting all virtual mappings of the 2589 * subpages. If the total_mapcount is equal to "one", it tells the 2590 * caller all mappings belong to the same "mm" and in turn the 2591 * anon_vma of the transparent hugepage can become the vma->anon_vma 2592 * local one as no other process may be mapping any of the subpages. 2593 * 2594 * It would be more accurate to replace page_mapcount() with 2595 * page_trans_huge_mapcount(), however we only use 2596 * page_trans_huge_mapcount() in the copy-on-write faults where we 2597 * need full accuracy to avoid breaking page pinning, because 2598 * page_trans_huge_mapcount() is slower than page_mapcount(). 2599 */ 2600 int page_trans_huge_mapcount(struct page *page, int *total_mapcount) 2601 { 2602 int i, ret, _total_mapcount, mapcount; 2603 2604 /* hugetlbfs shouldn't call it */ 2605 VM_BUG_ON_PAGE(PageHuge(page), page); 2606 2607 if (likely(!PageTransCompound(page))) { 2608 mapcount = atomic_read(&page->_mapcount) + 1; 2609 if (total_mapcount) 2610 *total_mapcount = mapcount; 2611 return mapcount; 2612 } 2613 2614 page = compound_head(page); 2615 2616 _total_mapcount = ret = 0; 2617 for (i = 0; i < thp_nr_pages(page); i++) { 2618 mapcount = atomic_read(&page[i]._mapcount) + 1; 2619 ret = max(ret, mapcount); 2620 _total_mapcount += mapcount; 2621 } 2622 if (PageDoubleMap(page)) { 2623 ret -= 1; 2624 _total_mapcount -= thp_nr_pages(page); 2625 } 2626 mapcount = compound_mapcount(page); 2627 ret += mapcount; 2628 _total_mapcount += mapcount; 2629 if (total_mapcount) 2630 *total_mapcount = _total_mapcount; 2631 return ret; 2632 } 2633 2634 /* Racy check whether the huge page can be split */ 2635 bool can_split_huge_page(struct page *page, int *pextra_pins) 2636 { 2637 int extra_pins; 2638 2639 /* Additional pins from page cache */ 2640 if (PageAnon(page)) 2641 extra_pins = PageSwapCache(page) ? thp_nr_pages(page) : 0; 2642 else 2643 extra_pins = thp_nr_pages(page); 2644 if (pextra_pins) 2645 *pextra_pins = extra_pins; 2646 return total_mapcount(page) == page_count(page) - extra_pins - 1; 2647 } 2648 2649 /* 2650 * This function splits huge page into normal pages. @page can point to any 2651 * subpage of huge page to split. Split doesn't change the position of @page. 2652 * 2653 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2654 * The huge page must be locked. 2655 * 2656 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2657 * 2658 * Both head page and tail pages will inherit mapping, flags, and so on from 2659 * the hugepage. 2660 * 2661 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2662 * they are not mapped. 2663 * 2664 * Returns 0 if the hugepage is split successfully. 2665 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2666 * us. 2667 */ 2668 int split_huge_page_to_list(struct page *page, struct list_head *list) 2669 { 2670 struct page *head = compound_head(page); 2671 struct deferred_split *ds_queue = get_deferred_split_queue(head); 2672 struct anon_vma *anon_vma = NULL; 2673 struct address_space *mapping = NULL; 2674 int count, mapcount, extra_pins, ret; 2675 pgoff_t end; 2676 2677 VM_BUG_ON_PAGE(is_huge_zero_page(head), head); 2678 VM_BUG_ON_PAGE(!PageLocked(head), head); 2679 VM_BUG_ON_PAGE(!PageCompound(head), head); 2680 2681 if (PageWriteback(head)) 2682 return -EBUSY; 2683 2684 if (PageAnon(head)) { 2685 /* 2686 * The caller does not necessarily hold an mmap_lock that would 2687 * prevent the anon_vma disappearing so we first we take a 2688 * reference to it and then lock the anon_vma for write. This 2689 * is similar to page_lock_anon_vma_read except the write lock 2690 * is taken to serialise against parallel split or collapse 2691 * operations. 2692 */ 2693 anon_vma = page_get_anon_vma(head); 2694 if (!anon_vma) { 2695 ret = -EBUSY; 2696 goto out; 2697 } 2698 end = -1; 2699 mapping = NULL; 2700 anon_vma_lock_write(anon_vma); 2701 } else { 2702 mapping = head->mapping; 2703 2704 /* Truncated ? */ 2705 if (!mapping) { 2706 ret = -EBUSY; 2707 goto out; 2708 } 2709 2710 anon_vma = NULL; 2711 i_mmap_lock_read(mapping); 2712 2713 /* 2714 *__split_huge_page() may need to trim off pages beyond EOF: 2715 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2716 * which cannot be nested inside the page tree lock. So note 2717 * end now: i_size itself may be changed at any moment, but 2718 * head page lock is good enough to serialize the trimming. 2719 */ 2720 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2721 } 2722 2723 /* 2724 * Racy check if we can split the page, before unmap_page() will 2725 * split PMDs 2726 */ 2727 if (!can_split_huge_page(head, &extra_pins)) { 2728 ret = -EBUSY; 2729 goto out_unlock; 2730 } 2731 2732 unmap_page(head); 2733 VM_BUG_ON_PAGE(compound_mapcount(head), head); 2734 2735 /* block interrupt reentry in xa_lock and spinlock */ 2736 local_irq_disable(); 2737 if (mapping) { 2738 XA_STATE(xas, &mapping->i_pages, page_index(head)); 2739 2740 /* 2741 * Check if the head page is present in page cache. 2742 * We assume all tail are present too, if head is there. 2743 */ 2744 xa_lock(&mapping->i_pages); 2745 if (xas_load(&xas) != head) 2746 goto fail; 2747 } 2748 2749 /* Prevent deferred_split_scan() touching ->_refcount */ 2750 spin_lock(&ds_queue->split_queue_lock); 2751 count = page_count(head); 2752 mapcount = total_mapcount(head); 2753 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) { 2754 if (!list_empty(page_deferred_list(head))) { 2755 ds_queue->split_queue_len--; 2756 list_del(page_deferred_list(head)); 2757 } 2758 spin_unlock(&ds_queue->split_queue_lock); 2759 if (mapping) { 2760 int nr = thp_nr_pages(head); 2761 2762 if (PageSwapBacked(head)) 2763 __mod_lruvec_page_state(head, NR_SHMEM_THPS, 2764 -nr); 2765 else 2766 __mod_lruvec_page_state(head, NR_FILE_THPS, 2767 -nr); 2768 } 2769 2770 __split_huge_page(page, list, end); 2771 ret = 0; 2772 } else { 2773 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { 2774 pr_alert("total_mapcount: %u, page_count(): %u\n", 2775 mapcount, count); 2776 if (PageTail(page)) 2777 dump_page(head, NULL); 2778 dump_page(page, "total_mapcount(head) > 0"); 2779 BUG(); 2780 } 2781 spin_unlock(&ds_queue->split_queue_lock); 2782 fail: if (mapping) 2783 xa_unlock(&mapping->i_pages); 2784 local_irq_enable(); 2785 remap_page(head, thp_nr_pages(head)); 2786 ret = -EBUSY; 2787 } 2788 2789 out_unlock: 2790 if (anon_vma) { 2791 anon_vma_unlock_write(anon_vma); 2792 put_anon_vma(anon_vma); 2793 } 2794 if (mapping) 2795 i_mmap_unlock_read(mapping); 2796 out: 2797 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2798 return ret; 2799 } 2800 2801 void free_transhuge_page(struct page *page) 2802 { 2803 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2804 unsigned long flags; 2805 2806 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2807 if (!list_empty(page_deferred_list(page))) { 2808 ds_queue->split_queue_len--; 2809 list_del(page_deferred_list(page)); 2810 } 2811 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2812 free_compound_page(page); 2813 } 2814 2815 void deferred_split_huge_page(struct page *page) 2816 { 2817 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2818 #ifdef CONFIG_MEMCG 2819 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 2820 #endif 2821 unsigned long flags; 2822 2823 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2824 2825 /* 2826 * The try_to_unmap() in page reclaim path might reach here too, 2827 * this may cause a race condition to corrupt deferred split queue. 2828 * And, if page reclaim is already handling the same page, it is 2829 * unnecessary to handle it again in shrinker. 2830 * 2831 * Check PageSwapCache to determine if the page is being 2832 * handled by page reclaim since THP swap would add the page into 2833 * swap cache before calling try_to_unmap(). 2834 */ 2835 if (PageSwapCache(page)) 2836 return; 2837 2838 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2839 if (list_empty(page_deferred_list(page))) { 2840 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2841 list_add_tail(page_deferred_list(page), &ds_queue->split_queue); 2842 ds_queue->split_queue_len++; 2843 #ifdef CONFIG_MEMCG 2844 if (memcg) 2845 memcg_set_shrinker_bit(memcg, page_to_nid(page), 2846 deferred_split_shrinker.id); 2847 #endif 2848 } 2849 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2850 } 2851 2852 static unsigned long deferred_split_count(struct shrinker *shrink, 2853 struct shrink_control *sc) 2854 { 2855 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2856 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2857 2858 #ifdef CONFIG_MEMCG 2859 if (sc->memcg) 2860 ds_queue = &sc->memcg->deferred_split_queue; 2861 #endif 2862 return READ_ONCE(ds_queue->split_queue_len); 2863 } 2864 2865 static unsigned long deferred_split_scan(struct shrinker *shrink, 2866 struct shrink_control *sc) 2867 { 2868 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2869 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2870 unsigned long flags; 2871 LIST_HEAD(list), *pos, *next; 2872 struct page *page; 2873 int split = 0; 2874 2875 #ifdef CONFIG_MEMCG 2876 if (sc->memcg) 2877 ds_queue = &sc->memcg->deferred_split_queue; 2878 #endif 2879 2880 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2881 /* Take pin on all head pages to avoid freeing them under us */ 2882 list_for_each_safe(pos, next, &ds_queue->split_queue) { 2883 page = list_entry((void *)pos, struct page, mapping); 2884 page = compound_head(page); 2885 if (get_page_unless_zero(page)) { 2886 list_move(page_deferred_list(page), &list); 2887 } else { 2888 /* We lost race with put_compound_page() */ 2889 list_del_init(page_deferred_list(page)); 2890 ds_queue->split_queue_len--; 2891 } 2892 if (!--sc->nr_to_scan) 2893 break; 2894 } 2895 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2896 2897 list_for_each_safe(pos, next, &list) { 2898 page = list_entry((void *)pos, struct page, mapping); 2899 if (!trylock_page(page)) 2900 goto next; 2901 /* split_huge_page() removes page from list on success */ 2902 if (!split_huge_page(page)) 2903 split++; 2904 unlock_page(page); 2905 next: 2906 put_page(page); 2907 } 2908 2909 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2910 list_splice_tail(&list, &ds_queue->split_queue); 2911 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2912 2913 /* 2914 * Stop shrinker if we didn't split any page, but the queue is empty. 2915 * This can happen if pages were freed under us. 2916 */ 2917 if (!split && list_empty(&ds_queue->split_queue)) 2918 return SHRINK_STOP; 2919 return split; 2920 } 2921 2922 static struct shrinker deferred_split_shrinker = { 2923 .count_objects = deferred_split_count, 2924 .scan_objects = deferred_split_scan, 2925 .seeks = DEFAULT_SEEKS, 2926 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | 2927 SHRINKER_NONSLAB, 2928 }; 2929 2930 #ifdef CONFIG_DEBUG_FS 2931 static int split_huge_pages_set(void *data, u64 val) 2932 { 2933 struct zone *zone; 2934 struct page *page; 2935 unsigned long pfn, max_zone_pfn; 2936 unsigned long total = 0, split = 0; 2937 2938 if (val != 1) 2939 return -EINVAL; 2940 2941 for_each_populated_zone(zone) { 2942 max_zone_pfn = zone_end_pfn(zone); 2943 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2944 if (!pfn_valid(pfn)) 2945 continue; 2946 2947 page = pfn_to_page(pfn); 2948 if (!get_page_unless_zero(page)) 2949 continue; 2950 2951 if (zone != page_zone(page)) 2952 goto next; 2953 2954 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 2955 goto next; 2956 2957 total++; 2958 lock_page(page); 2959 if (!split_huge_page(page)) 2960 split++; 2961 unlock_page(page); 2962 next: 2963 put_page(page); 2964 } 2965 } 2966 2967 pr_info("%lu of %lu THP split\n", split, total); 2968 2969 return 0; 2970 } 2971 DEFINE_DEBUGFS_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, 2972 "%llu\n"); 2973 2974 static int __init split_huge_pages_debugfs(void) 2975 { 2976 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 2977 &split_huge_pages_fops); 2978 return 0; 2979 } 2980 late_initcall(split_huge_pages_debugfs); 2981 #endif 2982 2983 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 2984 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 2985 struct page *page) 2986 { 2987 struct vm_area_struct *vma = pvmw->vma; 2988 struct mm_struct *mm = vma->vm_mm; 2989 unsigned long address = pvmw->address; 2990 pmd_t pmdval; 2991 swp_entry_t entry; 2992 pmd_t pmdswp; 2993 2994 if (!(pvmw->pmd && !pvmw->pte)) 2995 return; 2996 2997 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 2998 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 2999 if (pmd_dirty(pmdval)) 3000 set_page_dirty(page); 3001 entry = make_migration_entry(page, pmd_write(pmdval)); 3002 pmdswp = swp_entry_to_pmd(entry); 3003 if (pmd_soft_dirty(pmdval)) 3004 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3005 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3006 page_remove_rmap(page, true); 3007 put_page(page); 3008 } 3009 3010 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3011 { 3012 struct vm_area_struct *vma = pvmw->vma; 3013 struct mm_struct *mm = vma->vm_mm; 3014 unsigned long address = pvmw->address; 3015 unsigned long mmun_start = address & HPAGE_PMD_MASK; 3016 pmd_t pmde; 3017 swp_entry_t entry; 3018 3019 if (!(pvmw->pmd && !pvmw->pte)) 3020 return; 3021 3022 entry = pmd_to_swp_entry(*pvmw->pmd); 3023 get_page(new); 3024 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot)); 3025 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3026 pmde = pmd_mksoft_dirty(pmde); 3027 if (is_write_migration_entry(entry)) 3028 pmde = maybe_pmd_mkwrite(pmde, vma); 3029 3030 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE); 3031 if (PageAnon(new)) 3032 page_add_anon_rmap(new, vma, mmun_start, true); 3033 else 3034 page_add_file_rmap(new, true); 3035 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde); 3036 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new)) 3037 mlock_vma_page(new); 3038 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3039 } 3040 #endif 3041