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(page_needs_cow_for_dma(vma, src_page))) { 1104 pte_free(dst_mm, pgtable); 1105 spin_unlock(src_ptl); 1106 spin_unlock(dst_ptl); 1107 __split_huge_pmd(vma, src_pmd, addr, false, NULL); 1108 return -EAGAIN; 1109 } 1110 1111 get_page(src_page); 1112 page_dup_rmap(src_page, true); 1113 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1114 mm_inc_nr_ptes(dst_mm); 1115 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1116 1117 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1118 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1119 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1120 1121 ret = 0; 1122 out_unlock: 1123 spin_unlock(src_ptl); 1124 spin_unlock(dst_ptl); 1125 out: 1126 return ret; 1127 } 1128 1129 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1130 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1131 pud_t *pud, int flags) 1132 { 1133 pud_t _pud; 1134 1135 _pud = pud_mkyoung(*pud); 1136 if (flags & FOLL_WRITE) 1137 _pud = pud_mkdirty(_pud); 1138 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1139 pud, _pud, flags & FOLL_WRITE)) 1140 update_mmu_cache_pud(vma, addr, pud); 1141 } 1142 1143 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1144 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1145 { 1146 unsigned long pfn = pud_pfn(*pud); 1147 struct mm_struct *mm = vma->vm_mm; 1148 struct page *page; 1149 1150 assert_spin_locked(pud_lockptr(mm, pud)); 1151 1152 if (flags & FOLL_WRITE && !pud_write(*pud)) 1153 return NULL; 1154 1155 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1156 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1157 (FOLL_PIN | FOLL_GET))) 1158 return NULL; 1159 1160 if (pud_present(*pud) && pud_devmap(*pud)) 1161 /* pass */; 1162 else 1163 return NULL; 1164 1165 if (flags & FOLL_TOUCH) 1166 touch_pud(vma, addr, pud, flags); 1167 1168 /* 1169 * device mapped pages can only be returned if the 1170 * caller will manage the page reference count. 1171 * 1172 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here: 1173 */ 1174 if (!(flags & (FOLL_GET | FOLL_PIN))) 1175 return ERR_PTR(-EEXIST); 1176 1177 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1178 *pgmap = get_dev_pagemap(pfn, *pgmap); 1179 if (!*pgmap) 1180 return ERR_PTR(-EFAULT); 1181 page = pfn_to_page(pfn); 1182 if (!try_grab_page(page, flags)) 1183 page = ERR_PTR(-ENOMEM); 1184 1185 return page; 1186 } 1187 1188 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1189 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1190 struct vm_area_struct *vma) 1191 { 1192 spinlock_t *dst_ptl, *src_ptl; 1193 pud_t pud; 1194 int ret; 1195 1196 dst_ptl = pud_lock(dst_mm, dst_pud); 1197 src_ptl = pud_lockptr(src_mm, src_pud); 1198 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1199 1200 ret = -EAGAIN; 1201 pud = *src_pud; 1202 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1203 goto out_unlock; 1204 1205 /* 1206 * When page table lock is held, the huge zero pud should not be 1207 * under splitting since we don't split the page itself, only pud to 1208 * a page table. 1209 */ 1210 if (is_huge_zero_pud(pud)) { 1211 /* No huge zero pud yet */ 1212 } 1213 1214 /* Please refer to comments in copy_huge_pmd() */ 1215 if (unlikely(page_needs_cow_for_dma(vma, pud_page(pud)))) { 1216 spin_unlock(src_ptl); 1217 spin_unlock(dst_ptl); 1218 __split_huge_pud(vma, src_pud, addr); 1219 return -EAGAIN; 1220 } 1221 1222 pudp_set_wrprotect(src_mm, addr, src_pud); 1223 pud = pud_mkold(pud_wrprotect(pud)); 1224 set_pud_at(dst_mm, addr, dst_pud, pud); 1225 1226 ret = 0; 1227 out_unlock: 1228 spin_unlock(src_ptl); 1229 spin_unlock(dst_ptl); 1230 return ret; 1231 } 1232 1233 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1234 { 1235 pud_t entry; 1236 unsigned long haddr; 1237 bool write = vmf->flags & FAULT_FLAG_WRITE; 1238 1239 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1240 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1241 goto unlock; 1242 1243 entry = pud_mkyoung(orig_pud); 1244 if (write) 1245 entry = pud_mkdirty(entry); 1246 haddr = vmf->address & HPAGE_PUD_MASK; 1247 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) 1248 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); 1249 1250 unlock: 1251 spin_unlock(vmf->ptl); 1252 } 1253 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1254 1255 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd) 1256 { 1257 pmd_t entry; 1258 unsigned long haddr; 1259 bool write = vmf->flags & FAULT_FLAG_WRITE; 1260 1261 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1262 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1263 goto unlock; 1264 1265 entry = pmd_mkyoung(orig_pmd); 1266 if (write) 1267 entry = pmd_mkdirty(entry); 1268 haddr = vmf->address & HPAGE_PMD_MASK; 1269 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) 1270 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); 1271 1272 unlock: 1273 spin_unlock(vmf->ptl); 1274 } 1275 1276 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) 1277 { 1278 struct vm_area_struct *vma = vmf->vma; 1279 struct page *page; 1280 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1281 1282 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1283 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1284 1285 if (is_huge_zero_pmd(orig_pmd)) 1286 goto fallback; 1287 1288 spin_lock(vmf->ptl); 1289 1290 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1291 spin_unlock(vmf->ptl); 1292 return 0; 1293 } 1294 1295 page = pmd_page(orig_pmd); 1296 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); 1297 1298 /* Lock page for reuse_swap_page() */ 1299 if (!trylock_page(page)) { 1300 get_page(page); 1301 spin_unlock(vmf->ptl); 1302 lock_page(page); 1303 spin_lock(vmf->ptl); 1304 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1305 spin_unlock(vmf->ptl); 1306 unlock_page(page); 1307 put_page(page); 1308 return 0; 1309 } 1310 put_page(page); 1311 } 1312 1313 /* 1314 * We can only reuse the page if nobody else maps the huge page or it's 1315 * part. 1316 */ 1317 if (reuse_swap_page(page, NULL)) { 1318 pmd_t entry; 1319 entry = pmd_mkyoung(orig_pmd); 1320 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1321 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1322 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1323 unlock_page(page); 1324 spin_unlock(vmf->ptl); 1325 return VM_FAULT_WRITE; 1326 } 1327 1328 unlock_page(page); 1329 spin_unlock(vmf->ptl); 1330 fallback: 1331 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1332 return VM_FAULT_FALLBACK; 1333 } 1334 1335 /* 1336 * FOLL_FORCE can write to even unwritable pmd's, but only 1337 * after we've gone through a COW cycle and they are dirty. 1338 */ 1339 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) 1340 { 1341 return pmd_write(pmd) || 1342 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); 1343 } 1344 1345 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1346 unsigned long addr, 1347 pmd_t *pmd, 1348 unsigned int flags) 1349 { 1350 struct mm_struct *mm = vma->vm_mm; 1351 struct page *page = NULL; 1352 1353 assert_spin_locked(pmd_lockptr(mm, pmd)); 1354 1355 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) 1356 goto out; 1357 1358 /* Avoid dumping huge zero page */ 1359 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1360 return ERR_PTR(-EFAULT); 1361 1362 /* Full NUMA hinting faults to serialise migration in fault paths */ 1363 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) 1364 goto out; 1365 1366 page = pmd_page(*pmd); 1367 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1368 1369 if (!try_grab_page(page, flags)) 1370 return ERR_PTR(-ENOMEM); 1371 1372 if (flags & FOLL_TOUCH) 1373 touch_pmd(vma, addr, pmd, flags); 1374 1375 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { 1376 /* 1377 * We don't mlock() pte-mapped THPs. This way we can avoid 1378 * leaking mlocked pages into non-VM_LOCKED VMAs. 1379 * 1380 * For anon THP: 1381 * 1382 * In most cases the pmd is the only mapping of the page as we 1383 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for 1384 * writable private mappings in populate_vma_page_range(). 1385 * 1386 * The only scenario when we have the page shared here is if we 1387 * mlocking read-only mapping shared over fork(). We skip 1388 * mlocking such pages. 1389 * 1390 * For file THP: 1391 * 1392 * We can expect PageDoubleMap() to be stable under page lock: 1393 * for file pages we set it in page_add_file_rmap(), which 1394 * requires page to be locked. 1395 */ 1396 1397 if (PageAnon(page) && compound_mapcount(page) != 1) 1398 goto skip_mlock; 1399 if (PageDoubleMap(page) || !page->mapping) 1400 goto skip_mlock; 1401 if (!trylock_page(page)) 1402 goto skip_mlock; 1403 if (page->mapping && !PageDoubleMap(page)) 1404 mlock_vma_page(page); 1405 unlock_page(page); 1406 } 1407 skip_mlock: 1408 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1409 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1410 1411 out: 1412 return page; 1413 } 1414 1415 /* NUMA hinting page fault entry point for trans huge pmds */ 1416 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) 1417 { 1418 struct vm_area_struct *vma = vmf->vma; 1419 struct anon_vma *anon_vma = NULL; 1420 struct page *page; 1421 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1422 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id(); 1423 int target_nid, last_cpupid = -1; 1424 bool page_locked; 1425 bool migrated = false; 1426 bool was_writable; 1427 int flags = 0; 1428 1429 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1430 if (unlikely(!pmd_same(pmd, *vmf->pmd))) 1431 goto out_unlock; 1432 1433 /* 1434 * If there are potential migrations, wait for completion and retry 1435 * without disrupting NUMA hinting information. Do not relock and 1436 * check_same as the page may no longer be mapped. 1437 */ 1438 if (unlikely(pmd_trans_migrating(*vmf->pmd))) { 1439 page = pmd_page(*vmf->pmd); 1440 if (!get_page_unless_zero(page)) 1441 goto out_unlock; 1442 spin_unlock(vmf->ptl); 1443 put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE); 1444 goto out; 1445 } 1446 1447 page = pmd_page(pmd); 1448 BUG_ON(is_huge_zero_page(page)); 1449 page_nid = page_to_nid(page); 1450 last_cpupid = page_cpupid_last(page); 1451 count_vm_numa_event(NUMA_HINT_FAULTS); 1452 if (page_nid == this_nid) { 1453 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 1454 flags |= TNF_FAULT_LOCAL; 1455 } 1456 1457 /* See similar comment in do_numa_page for explanation */ 1458 if (!pmd_savedwrite(pmd)) 1459 flags |= TNF_NO_GROUP; 1460 1461 /* 1462 * Acquire the page lock to serialise THP migrations but avoid dropping 1463 * page_table_lock if at all possible 1464 */ 1465 page_locked = trylock_page(page); 1466 target_nid = mpol_misplaced(page, vma, haddr); 1467 if (target_nid == NUMA_NO_NODE) { 1468 /* If the page was locked, there are no parallel migrations */ 1469 if (page_locked) 1470 goto clear_pmdnuma; 1471 } 1472 1473 /* Migration could have started since the pmd_trans_migrating check */ 1474 if (!page_locked) { 1475 page_nid = NUMA_NO_NODE; 1476 if (!get_page_unless_zero(page)) 1477 goto out_unlock; 1478 spin_unlock(vmf->ptl); 1479 put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE); 1480 goto out; 1481 } 1482 1483 /* 1484 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma 1485 * to serialises splits 1486 */ 1487 get_page(page); 1488 spin_unlock(vmf->ptl); 1489 anon_vma = page_lock_anon_vma_read(page); 1490 1491 /* Confirm the PMD did not change while page_table_lock was released */ 1492 spin_lock(vmf->ptl); 1493 if (unlikely(!pmd_same(pmd, *vmf->pmd))) { 1494 unlock_page(page); 1495 put_page(page); 1496 page_nid = NUMA_NO_NODE; 1497 goto out_unlock; 1498 } 1499 1500 /* Bail if we fail to protect against THP splits for any reason */ 1501 if (unlikely(!anon_vma)) { 1502 put_page(page); 1503 page_nid = NUMA_NO_NODE; 1504 goto clear_pmdnuma; 1505 } 1506 1507 /* 1508 * Since we took the NUMA fault, we must have observed the !accessible 1509 * bit. Make sure all other CPUs agree with that, to avoid them 1510 * modifying the page we're about to migrate. 1511 * 1512 * Must be done under PTL such that we'll observe the relevant 1513 * inc_tlb_flush_pending(). 1514 * 1515 * We are not sure a pending tlb flush here is for a huge page 1516 * mapping or not. Hence use the tlb range variant 1517 */ 1518 if (mm_tlb_flush_pending(vma->vm_mm)) { 1519 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE); 1520 /* 1521 * change_huge_pmd() released the pmd lock before 1522 * invalidating the secondary MMUs sharing the primary 1523 * MMU pagetables (with ->invalidate_range()). The 1524 * mmu_notifier_invalidate_range_end() (which 1525 * internally calls ->invalidate_range()) in 1526 * change_pmd_range() will run after us, so we can't 1527 * rely on it here and we need an explicit invalidate. 1528 */ 1529 mmu_notifier_invalidate_range(vma->vm_mm, haddr, 1530 haddr + HPAGE_PMD_SIZE); 1531 } 1532 1533 /* 1534 * Migrate the THP to the requested node, returns with page unlocked 1535 * and access rights restored. 1536 */ 1537 spin_unlock(vmf->ptl); 1538 1539 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma, 1540 vmf->pmd, pmd, vmf->address, page, target_nid); 1541 if (migrated) { 1542 flags |= TNF_MIGRATED; 1543 page_nid = target_nid; 1544 } else 1545 flags |= TNF_MIGRATE_FAIL; 1546 1547 goto out; 1548 clear_pmdnuma: 1549 BUG_ON(!PageLocked(page)); 1550 was_writable = pmd_savedwrite(pmd); 1551 pmd = pmd_modify(pmd, vma->vm_page_prot); 1552 pmd = pmd_mkyoung(pmd); 1553 if (was_writable) 1554 pmd = pmd_mkwrite(pmd); 1555 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1556 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1557 unlock_page(page); 1558 out_unlock: 1559 spin_unlock(vmf->ptl); 1560 1561 out: 1562 if (anon_vma) 1563 page_unlock_anon_vma_read(anon_vma); 1564 1565 if (page_nid != NUMA_NO_NODE) 1566 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1567 flags); 1568 1569 return 0; 1570 } 1571 1572 /* 1573 * Return true if we do MADV_FREE successfully on entire pmd page. 1574 * Otherwise, return false. 1575 */ 1576 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1577 pmd_t *pmd, unsigned long addr, unsigned long next) 1578 { 1579 spinlock_t *ptl; 1580 pmd_t orig_pmd; 1581 struct page *page; 1582 struct mm_struct *mm = tlb->mm; 1583 bool ret = false; 1584 1585 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1586 1587 ptl = pmd_trans_huge_lock(pmd, vma); 1588 if (!ptl) 1589 goto out_unlocked; 1590 1591 orig_pmd = *pmd; 1592 if (is_huge_zero_pmd(orig_pmd)) 1593 goto out; 1594 1595 if (unlikely(!pmd_present(orig_pmd))) { 1596 VM_BUG_ON(thp_migration_supported() && 1597 !is_pmd_migration_entry(orig_pmd)); 1598 goto out; 1599 } 1600 1601 page = pmd_page(orig_pmd); 1602 /* 1603 * If other processes are mapping this page, we couldn't discard 1604 * the page unless they all do MADV_FREE so let's skip the page. 1605 */ 1606 if (page_mapcount(page) != 1) 1607 goto out; 1608 1609 if (!trylock_page(page)) 1610 goto out; 1611 1612 /* 1613 * If user want to discard part-pages of THP, split it so MADV_FREE 1614 * will deactivate only them. 1615 */ 1616 if (next - addr != HPAGE_PMD_SIZE) { 1617 get_page(page); 1618 spin_unlock(ptl); 1619 split_huge_page(page); 1620 unlock_page(page); 1621 put_page(page); 1622 goto out_unlocked; 1623 } 1624 1625 if (PageDirty(page)) 1626 ClearPageDirty(page); 1627 unlock_page(page); 1628 1629 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1630 pmdp_invalidate(vma, addr, pmd); 1631 orig_pmd = pmd_mkold(orig_pmd); 1632 orig_pmd = pmd_mkclean(orig_pmd); 1633 1634 set_pmd_at(mm, addr, pmd, orig_pmd); 1635 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1636 } 1637 1638 mark_page_lazyfree(page); 1639 ret = true; 1640 out: 1641 spin_unlock(ptl); 1642 out_unlocked: 1643 return ret; 1644 } 1645 1646 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1647 { 1648 pgtable_t pgtable; 1649 1650 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1651 pte_free(mm, pgtable); 1652 mm_dec_nr_ptes(mm); 1653 } 1654 1655 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1656 pmd_t *pmd, unsigned long addr) 1657 { 1658 pmd_t orig_pmd; 1659 spinlock_t *ptl; 1660 1661 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1662 1663 ptl = __pmd_trans_huge_lock(pmd, vma); 1664 if (!ptl) 1665 return 0; 1666 /* 1667 * For architectures like ppc64 we look at deposited pgtable 1668 * when calling pmdp_huge_get_and_clear. So do the 1669 * pgtable_trans_huge_withdraw after finishing pmdp related 1670 * operations. 1671 */ 1672 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1673 tlb->fullmm); 1674 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1675 if (vma_is_special_huge(vma)) { 1676 if (arch_needs_pgtable_deposit()) 1677 zap_deposited_table(tlb->mm, pmd); 1678 spin_unlock(ptl); 1679 if (is_huge_zero_pmd(orig_pmd)) 1680 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1681 } else if (is_huge_zero_pmd(orig_pmd)) { 1682 zap_deposited_table(tlb->mm, pmd); 1683 spin_unlock(ptl); 1684 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1685 } else { 1686 struct page *page = NULL; 1687 int flush_needed = 1; 1688 1689 if (pmd_present(orig_pmd)) { 1690 page = pmd_page(orig_pmd); 1691 page_remove_rmap(page, true); 1692 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1693 VM_BUG_ON_PAGE(!PageHead(page), page); 1694 } else if (thp_migration_supported()) { 1695 swp_entry_t entry; 1696 1697 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1698 entry = pmd_to_swp_entry(orig_pmd); 1699 page = pfn_to_page(swp_offset(entry)); 1700 flush_needed = 0; 1701 } else 1702 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1703 1704 if (PageAnon(page)) { 1705 zap_deposited_table(tlb->mm, pmd); 1706 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1707 } else { 1708 if (arch_needs_pgtable_deposit()) 1709 zap_deposited_table(tlb->mm, pmd); 1710 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1711 } 1712 1713 spin_unlock(ptl); 1714 if (flush_needed) 1715 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1716 } 1717 return 1; 1718 } 1719 1720 #ifndef pmd_move_must_withdraw 1721 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1722 spinlock_t *old_pmd_ptl, 1723 struct vm_area_struct *vma) 1724 { 1725 /* 1726 * With split pmd lock we also need to move preallocated 1727 * PTE page table if new_pmd is on different PMD page table. 1728 * 1729 * We also don't deposit and withdraw tables for file pages. 1730 */ 1731 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1732 } 1733 #endif 1734 1735 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1736 { 1737 #ifdef CONFIG_MEM_SOFT_DIRTY 1738 if (unlikely(is_pmd_migration_entry(pmd))) 1739 pmd = pmd_swp_mksoft_dirty(pmd); 1740 else if (pmd_present(pmd)) 1741 pmd = pmd_mksoft_dirty(pmd); 1742 #endif 1743 return pmd; 1744 } 1745 1746 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1747 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1748 { 1749 spinlock_t *old_ptl, *new_ptl; 1750 pmd_t pmd; 1751 struct mm_struct *mm = vma->vm_mm; 1752 bool force_flush = false; 1753 1754 /* 1755 * The destination pmd shouldn't be established, free_pgtables() 1756 * should have release it. 1757 */ 1758 if (WARN_ON(!pmd_none(*new_pmd))) { 1759 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1760 return false; 1761 } 1762 1763 /* 1764 * We don't have to worry about the ordering of src and dst 1765 * ptlocks because exclusive mmap_lock prevents deadlock. 1766 */ 1767 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1768 if (old_ptl) { 1769 new_ptl = pmd_lockptr(mm, new_pmd); 1770 if (new_ptl != old_ptl) 1771 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1772 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1773 if (pmd_present(pmd)) 1774 force_flush = true; 1775 VM_BUG_ON(!pmd_none(*new_pmd)); 1776 1777 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1778 pgtable_t pgtable; 1779 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1780 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1781 } 1782 pmd = move_soft_dirty_pmd(pmd); 1783 set_pmd_at(mm, new_addr, new_pmd, pmd); 1784 if (force_flush) 1785 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1786 if (new_ptl != old_ptl) 1787 spin_unlock(new_ptl); 1788 spin_unlock(old_ptl); 1789 return true; 1790 } 1791 return false; 1792 } 1793 1794 /* 1795 * Returns 1796 * - 0 if PMD could not be locked 1797 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary 1798 * - HPAGE_PMD_NR is protections changed and TLB flush necessary 1799 */ 1800 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 1801 unsigned long addr, pgprot_t newprot, unsigned long cp_flags) 1802 { 1803 struct mm_struct *mm = vma->vm_mm; 1804 spinlock_t *ptl; 1805 pmd_t entry; 1806 bool preserve_write; 1807 int ret; 1808 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1809 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1810 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1811 1812 ptl = __pmd_trans_huge_lock(pmd, vma); 1813 if (!ptl) 1814 return 0; 1815 1816 preserve_write = prot_numa && pmd_write(*pmd); 1817 ret = 1; 1818 1819 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1820 if (is_swap_pmd(*pmd)) { 1821 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1822 1823 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1824 if (is_write_migration_entry(entry)) { 1825 pmd_t newpmd; 1826 /* 1827 * A protection check is difficult so 1828 * just be safe and disable write 1829 */ 1830 make_migration_entry_read(&entry); 1831 newpmd = swp_entry_to_pmd(entry); 1832 if (pmd_swp_soft_dirty(*pmd)) 1833 newpmd = pmd_swp_mksoft_dirty(newpmd); 1834 set_pmd_at(mm, addr, pmd, newpmd); 1835 } 1836 goto unlock; 1837 } 1838 #endif 1839 1840 /* 1841 * Avoid trapping faults against the zero page. The read-only 1842 * data is likely to be read-cached on the local CPU and 1843 * local/remote hits to the zero page are not interesting. 1844 */ 1845 if (prot_numa && is_huge_zero_pmd(*pmd)) 1846 goto unlock; 1847 1848 if (prot_numa && pmd_protnone(*pmd)) 1849 goto unlock; 1850 1851 /* 1852 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 1853 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1854 * which is also under mmap_read_lock(mm): 1855 * 1856 * CPU0: CPU1: 1857 * change_huge_pmd(prot_numa=1) 1858 * pmdp_huge_get_and_clear_notify() 1859 * madvise_dontneed() 1860 * zap_pmd_range() 1861 * pmd_trans_huge(*pmd) == 0 (without ptl) 1862 * // skip the pmd 1863 * set_pmd_at(); 1864 * // pmd is re-established 1865 * 1866 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1867 * which may break userspace. 1868 * 1869 * pmdp_invalidate() is required to make sure we don't miss 1870 * dirty/young flags set by hardware. 1871 */ 1872 entry = pmdp_invalidate(vma, addr, pmd); 1873 1874 entry = pmd_modify(entry, newprot); 1875 if (preserve_write) 1876 entry = pmd_mk_savedwrite(entry); 1877 if (uffd_wp) { 1878 entry = pmd_wrprotect(entry); 1879 entry = pmd_mkuffd_wp(entry); 1880 } else if (uffd_wp_resolve) { 1881 /* 1882 * Leave the write bit to be handled by PF interrupt 1883 * handler, then things like COW could be properly 1884 * handled. 1885 */ 1886 entry = pmd_clear_uffd_wp(entry); 1887 } 1888 ret = HPAGE_PMD_NR; 1889 set_pmd_at(mm, addr, pmd, entry); 1890 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); 1891 unlock: 1892 spin_unlock(ptl); 1893 return ret; 1894 } 1895 1896 /* 1897 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1898 * 1899 * Note that if it returns page table lock pointer, this routine returns without 1900 * unlocking page table lock. So callers must unlock it. 1901 */ 1902 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1903 { 1904 spinlock_t *ptl; 1905 ptl = pmd_lock(vma->vm_mm, pmd); 1906 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 1907 pmd_devmap(*pmd))) 1908 return ptl; 1909 spin_unlock(ptl); 1910 return NULL; 1911 } 1912 1913 /* 1914 * Returns true if a given pud maps a thp, false otherwise. 1915 * 1916 * Note that if it returns true, this routine returns without unlocking page 1917 * table lock. So callers must unlock it. 1918 */ 1919 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 1920 { 1921 spinlock_t *ptl; 1922 1923 ptl = pud_lock(vma->vm_mm, pud); 1924 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 1925 return ptl; 1926 spin_unlock(ptl); 1927 return NULL; 1928 } 1929 1930 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1931 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 1932 pud_t *pud, unsigned long addr) 1933 { 1934 spinlock_t *ptl; 1935 1936 ptl = __pud_trans_huge_lock(pud, vma); 1937 if (!ptl) 1938 return 0; 1939 /* 1940 * For architectures like ppc64 we look at deposited pgtable 1941 * when calling pudp_huge_get_and_clear. So do the 1942 * pgtable_trans_huge_withdraw after finishing pudp related 1943 * operations. 1944 */ 1945 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 1946 tlb_remove_pud_tlb_entry(tlb, pud, addr); 1947 if (vma_is_special_huge(vma)) { 1948 spin_unlock(ptl); 1949 /* No zero page support yet */ 1950 } else { 1951 /* No support for anonymous PUD pages yet */ 1952 BUG(); 1953 } 1954 return 1; 1955 } 1956 1957 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 1958 unsigned long haddr) 1959 { 1960 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 1961 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 1962 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 1963 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 1964 1965 count_vm_event(THP_SPLIT_PUD); 1966 1967 pudp_huge_clear_flush_notify(vma, haddr, pud); 1968 } 1969 1970 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 1971 unsigned long address) 1972 { 1973 spinlock_t *ptl; 1974 struct mmu_notifier_range range; 1975 1976 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1977 address & HPAGE_PUD_MASK, 1978 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 1979 mmu_notifier_invalidate_range_start(&range); 1980 ptl = pud_lock(vma->vm_mm, pud); 1981 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 1982 goto out; 1983 __split_huge_pud_locked(vma, pud, range.start); 1984 1985 out: 1986 spin_unlock(ptl); 1987 /* 1988 * No need to double call mmu_notifier->invalidate_range() callback as 1989 * the above pudp_huge_clear_flush_notify() did already call it. 1990 */ 1991 mmu_notifier_invalidate_range_only_end(&range); 1992 } 1993 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1994 1995 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 1996 unsigned long haddr, pmd_t *pmd) 1997 { 1998 struct mm_struct *mm = vma->vm_mm; 1999 pgtable_t pgtable; 2000 pmd_t _pmd; 2001 int i; 2002 2003 /* 2004 * Leave pmd empty until pte is filled note that it is fine to delay 2005 * notification until mmu_notifier_invalidate_range_end() as we are 2006 * replacing a zero pmd write protected page with a zero pte write 2007 * protected page. 2008 * 2009 * See Documentation/vm/mmu_notifier.rst 2010 */ 2011 pmdp_huge_clear_flush(vma, haddr, pmd); 2012 2013 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2014 pmd_populate(mm, &_pmd, pgtable); 2015 2016 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 2017 pte_t *pte, entry; 2018 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 2019 entry = pte_mkspecial(entry); 2020 pte = pte_offset_map(&_pmd, haddr); 2021 VM_BUG_ON(!pte_none(*pte)); 2022 set_pte_at(mm, haddr, pte, entry); 2023 pte_unmap(pte); 2024 } 2025 smp_wmb(); /* make pte visible before pmd */ 2026 pmd_populate(mm, pmd, pgtable); 2027 } 2028 2029 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2030 unsigned long haddr, bool freeze) 2031 { 2032 struct mm_struct *mm = vma->vm_mm; 2033 struct page *page; 2034 pgtable_t pgtable; 2035 pmd_t old_pmd, _pmd; 2036 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 2037 unsigned long addr; 2038 int i; 2039 2040 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2041 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2042 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2043 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2044 && !pmd_devmap(*pmd)); 2045 2046 count_vm_event(THP_SPLIT_PMD); 2047 2048 if (!vma_is_anonymous(vma)) { 2049 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 2050 /* 2051 * We are going to unmap this huge page. So 2052 * just go ahead and zap it 2053 */ 2054 if (arch_needs_pgtable_deposit()) 2055 zap_deposited_table(mm, pmd); 2056 if (vma_is_special_huge(vma)) 2057 return; 2058 page = pmd_page(_pmd); 2059 if (!PageDirty(page) && pmd_dirty(_pmd)) 2060 set_page_dirty(page); 2061 if (!PageReferenced(page) && pmd_young(_pmd)) 2062 SetPageReferenced(page); 2063 page_remove_rmap(page, true); 2064 put_page(page); 2065 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2066 return; 2067 } else if (pmd_trans_huge(*pmd) && is_huge_zero_pmd(*pmd)) { 2068 /* 2069 * FIXME: Do we want to invalidate secondary mmu by calling 2070 * mmu_notifier_invalidate_range() see comments below inside 2071 * __split_huge_pmd() ? 2072 * 2073 * We are going from a zero huge page write protected to zero 2074 * small page also write protected so it does not seems useful 2075 * to invalidate secondary mmu at this time. 2076 */ 2077 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2078 } 2079 2080 /* 2081 * Up to this point the pmd is present and huge and userland has the 2082 * whole access to the hugepage during the split (which happens in 2083 * place). If we overwrite the pmd with the not-huge version pointing 2084 * to the pte here (which of course we could if all CPUs were bug 2085 * free), userland could trigger a small page size TLB miss on the 2086 * small sized TLB while the hugepage TLB entry is still established in 2087 * the huge TLB. Some CPU doesn't like that. 2088 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2089 * 383 on page 105. Intel should be safe but is also warns that it's 2090 * only safe if the permission and cache attributes of the two entries 2091 * loaded in the two TLB is identical (which should be the case here). 2092 * But it is generally safer to never allow small and huge TLB entries 2093 * for the same virtual address to be loaded simultaneously. So instead 2094 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2095 * current pmd notpresent (atomically because here the pmd_trans_huge 2096 * must remain set at all times on the pmd until the split is complete 2097 * for this pmd), then we flush the SMP TLB and finally we write the 2098 * non-huge version of the pmd entry with pmd_populate. 2099 */ 2100 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2101 2102 pmd_migration = is_pmd_migration_entry(old_pmd); 2103 if (unlikely(pmd_migration)) { 2104 swp_entry_t entry; 2105 2106 entry = pmd_to_swp_entry(old_pmd); 2107 page = pfn_to_page(swp_offset(entry)); 2108 write = is_write_migration_entry(entry); 2109 young = false; 2110 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2111 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2112 } else { 2113 page = pmd_page(old_pmd); 2114 if (pmd_dirty(old_pmd)) 2115 SetPageDirty(page); 2116 write = pmd_write(old_pmd); 2117 young = pmd_young(old_pmd); 2118 soft_dirty = pmd_soft_dirty(old_pmd); 2119 uffd_wp = pmd_uffd_wp(old_pmd); 2120 } 2121 VM_BUG_ON_PAGE(!page_count(page), page); 2122 page_ref_add(page, HPAGE_PMD_NR - 1); 2123 2124 /* 2125 * Withdraw the table only after we mark the pmd entry invalid. 2126 * This's critical for some architectures (Power). 2127 */ 2128 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2129 pmd_populate(mm, &_pmd, pgtable); 2130 2131 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2132 pte_t entry, *pte; 2133 /* 2134 * Note that NUMA hinting access restrictions are not 2135 * transferred to avoid any possibility of altering 2136 * permissions across VMAs. 2137 */ 2138 if (freeze || pmd_migration) { 2139 swp_entry_t swp_entry; 2140 swp_entry = make_migration_entry(page + i, write); 2141 entry = swp_entry_to_pte(swp_entry); 2142 if (soft_dirty) 2143 entry = pte_swp_mksoft_dirty(entry); 2144 if (uffd_wp) 2145 entry = pte_swp_mkuffd_wp(entry); 2146 } else { 2147 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2148 entry = maybe_mkwrite(entry, vma); 2149 if (!write) 2150 entry = pte_wrprotect(entry); 2151 if (!young) 2152 entry = pte_mkold(entry); 2153 if (soft_dirty) 2154 entry = pte_mksoft_dirty(entry); 2155 if (uffd_wp) 2156 entry = pte_mkuffd_wp(entry); 2157 } 2158 pte = pte_offset_map(&_pmd, addr); 2159 BUG_ON(!pte_none(*pte)); 2160 set_pte_at(mm, addr, pte, entry); 2161 if (!pmd_migration) 2162 atomic_inc(&page[i]._mapcount); 2163 pte_unmap(pte); 2164 } 2165 2166 if (!pmd_migration) { 2167 /* 2168 * Set PG_double_map before dropping compound_mapcount to avoid 2169 * false-negative page_mapped(). 2170 */ 2171 if (compound_mapcount(page) > 1 && 2172 !TestSetPageDoubleMap(page)) { 2173 for (i = 0; i < HPAGE_PMD_NR; i++) 2174 atomic_inc(&page[i]._mapcount); 2175 } 2176 2177 lock_page_memcg(page); 2178 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { 2179 /* Last compound_mapcount is gone. */ 2180 __mod_lruvec_page_state(page, NR_ANON_THPS, 2181 -HPAGE_PMD_NR); 2182 if (TestClearPageDoubleMap(page)) { 2183 /* No need in mapcount reference anymore */ 2184 for (i = 0; i < HPAGE_PMD_NR; i++) 2185 atomic_dec(&page[i]._mapcount); 2186 } 2187 } 2188 unlock_page_memcg(page); 2189 } 2190 2191 smp_wmb(); /* make pte visible before pmd */ 2192 pmd_populate(mm, pmd, pgtable); 2193 2194 if (freeze) { 2195 for (i = 0; i < HPAGE_PMD_NR; i++) { 2196 page_remove_rmap(page + i, false); 2197 put_page(page + i); 2198 } 2199 } 2200 } 2201 2202 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2203 unsigned long address, bool freeze, struct page *page) 2204 { 2205 spinlock_t *ptl; 2206 struct mmu_notifier_range range; 2207 bool do_unlock_page = false; 2208 pmd_t _pmd; 2209 2210 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2211 address & HPAGE_PMD_MASK, 2212 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2213 mmu_notifier_invalidate_range_start(&range); 2214 ptl = pmd_lock(vma->vm_mm, pmd); 2215 2216 /* 2217 * If caller asks to setup a migration entries, we need a page to check 2218 * pmd against. Otherwise we can end up replacing wrong page. 2219 */ 2220 VM_BUG_ON(freeze && !page); 2221 if (page) { 2222 VM_WARN_ON_ONCE(!PageLocked(page)); 2223 if (page != pmd_page(*pmd)) 2224 goto out; 2225 } 2226 2227 repeat: 2228 if (pmd_trans_huge(*pmd)) { 2229 if (!page) { 2230 page = pmd_page(*pmd); 2231 /* 2232 * An anonymous page must be locked, to ensure that a 2233 * concurrent reuse_swap_page() sees stable mapcount; 2234 * but reuse_swap_page() is not used on shmem or file, 2235 * and page lock must not be taken when zap_pmd_range() 2236 * calls __split_huge_pmd() while i_mmap_lock is held. 2237 */ 2238 if (PageAnon(page)) { 2239 if (unlikely(!trylock_page(page))) { 2240 get_page(page); 2241 _pmd = *pmd; 2242 spin_unlock(ptl); 2243 lock_page(page); 2244 spin_lock(ptl); 2245 if (unlikely(!pmd_same(*pmd, _pmd))) { 2246 unlock_page(page); 2247 put_page(page); 2248 page = NULL; 2249 goto repeat; 2250 } 2251 put_page(page); 2252 } 2253 do_unlock_page = true; 2254 } 2255 } 2256 if (PageMlocked(page)) 2257 clear_page_mlock(page); 2258 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd))) 2259 goto out; 2260 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2261 out: 2262 spin_unlock(ptl); 2263 if (do_unlock_page) 2264 unlock_page(page); 2265 /* 2266 * No need to double call mmu_notifier->invalidate_range() callback. 2267 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2268 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2269 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2270 * fault will trigger a flush_notify before pointing to a new page 2271 * (it is fine if the secondary mmu keeps pointing to the old zero 2272 * page in the meantime) 2273 * 3) Split a huge pmd into pte pointing to the same page. No need 2274 * to invalidate secondary tlb entry they are all still valid. 2275 * any further changes to individual pte will notify. So no need 2276 * to call mmu_notifier->invalidate_range() 2277 */ 2278 mmu_notifier_invalidate_range_only_end(&range); 2279 } 2280 2281 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2282 bool freeze, struct page *page) 2283 { 2284 pgd_t *pgd; 2285 p4d_t *p4d; 2286 pud_t *pud; 2287 pmd_t *pmd; 2288 2289 pgd = pgd_offset(vma->vm_mm, address); 2290 if (!pgd_present(*pgd)) 2291 return; 2292 2293 p4d = p4d_offset(pgd, address); 2294 if (!p4d_present(*p4d)) 2295 return; 2296 2297 pud = pud_offset(p4d, address); 2298 if (!pud_present(*pud)) 2299 return; 2300 2301 pmd = pmd_offset(pud, address); 2302 2303 __split_huge_pmd(vma, pmd, address, freeze, page); 2304 } 2305 2306 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2307 unsigned long start, 2308 unsigned long end, 2309 long adjust_next) 2310 { 2311 /* 2312 * If the new start address isn't hpage aligned and it could 2313 * previously contain an hugepage: check if we need to split 2314 * an huge pmd. 2315 */ 2316 if (start & ~HPAGE_PMD_MASK && 2317 (start & HPAGE_PMD_MASK) >= vma->vm_start && 2318 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2319 split_huge_pmd_address(vma, start, false, NULL); 2320 2321 /* 2322 * If the new end address isn't hpage aligned and it could 2323 * previously contain an hugepage: check if we need to split 2324 * an huge pmd. 2325 */ 2326 if (end & ~HPAGE_PMD_MASK && 2327 (end & HPAGE_PMD_MASK) >= vma->vm_start && 2328 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2329 split_huge_pmd_address(vma, end, false, NULL); 2330 2331 /* 2332 * If we're also updating the vma->vm_next->vm_start, if the new 2333 * vm_next->vm_start isn't hpage aligned and it could previously 2334 * contain an hugepage: check if we need to split an huge pmd. 2335 */ 2336 if (adjust_next > 0) { 2337 struct vm_area_struct *next = vma->vm_next; 2338 unsigned long nstart = next->vm_start; 2339 nstart += adjust_next; 2340 if (nstart & ~HPAGE_PMD_MASK && 2341 (nstart & HPAGE_PMD_MASK) >= next->vm_start && 2342 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) 2343 split_huge_pmd_address(next, nstart, false, NULL); 2344 } 2345 } 2346 2347 static void unmap_page(struct page *page) 2348 { 2349 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | 2350 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD; 2351 bool unmap_success; 2352 2353 VM_BUG_ON_PAGE(!PageHead(page), page); 2354 2355 if (PageAnon(page)) 2356 ttu_flags |= TTU_SPLIT_FREEZE; 2357 2358 unmap_success = try_to_unmap(page, ttu_flags); 2359 VM_BUG_ON_PAGE(!unmap_success, page); 2360 } 2361 2362 static void remap_page(struct page *page, unsigned int nr) 2363 { 2364 int i; 2365 if (PageTransHuge(page)) { 2366 remove_migration_ptes(page, page, true); 2367 } else { 2368 for (i = 0; i < nr; i++) 2369 remove_migration_ptes(page + i, page + i, true); 2370 } 2371 } 2372 2373 static void lru_add_page_tail(struct page *head, struct page *tail, 2374 struct lruvec *lruvec, struct list_head *list) 2375 { 2376 VM_BUG_ON_PAGE(!PageHead(head), head); 2377 VM_BUG_ON_PAGE(PageCompound(tail), head); 2378 VM_BUG_ON_PAGE(PageLRU(tail), head); 2379 lockdep_assert_held(&lruvec->lru_lock); 2380 2381 if (list) { 2382 /* page reclaim is reclaiming a huge page */ 2383 VM_WARN_ON(PageLRU(head)); 2384 get_page(tail); 2385 list_add_tail(&tail->lru, list); 2386 } else { 2387 /* head is still on lru (and we have it frozen) */ 2388 VM_WARN_ON(!PageLRU(head)); 2389 SetPageLRU(tail); 2390 list_add_tail(&tail->lru, &head->lru); 2391 } 2392 } 2393 2394 static void __split_huge_page_tail(struct page *head, int tail, 2395 struct lruvec *lruvec, struct list_head *list) 2396 { 2397 struct page *page_tail = head + tail; 2398 2399 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2400 2401 /* 2402 * Clone page flags before unfreezing refcount. 2403 * 2404 * After successful get_page_unless_zero() might follow flags change, 2405 * for example lock_page() which set PG_waiters. 2406 */ 2407 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2408 page_tail->flags |= (head->flags & 2409 ((1L << PG_referenced) | 2410 (1L << PG_swapbacked) | 2411 (1L << PG_swapcache) | 2412 (1L << PG_mlocked) | 2413 (1L << PG_uptodate) | 2414 (1L << PG_active) | 2415 (1L << PG_workingset) | 2416 (1L << PG_locked) | 2417 (1L << PG_unevictable) | 2418 #ifdef CONFIG_64BIT 2419 (1L << PG_arch_2) | 2420 #endif 2421 (1L << PG_dirty))); 2422 2423 /* ->mapping in first tail page is compound_mapcount */ 2424 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2425 page_tail); 2426 page_tail->mapping = head->mapping; 2427 page_tail->index = head->index + tail; 2428 2429 /* Page flags must be visible before we make the page non-compound. */ 2430 smp_wmb(); 2431 2432 /* 2433 * Clear PageTail before unfreezing page refcount. 2434 * 2435 * After successful get_page_unless_zero() might follow put_page() 2436 * which needs correct compound_head(). 2437 */ 2438 clear_compound_head(page_tail); 2439 2440 /* Finally unfreeze refcount. Additional reference from page cache. */ 2441 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2442 PageSwapCache(head))); 2443 2444 if (page_is_young(head)) 2445 set_page_young(page_tail); 2446 if (page_is_idle(head)) 2447 set_page_idle(page_tail); 2448 2449 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2450 2451 /* 2452 * always add to the tail because some iterators expect new 2453 * pages to show after the currently processed elements - e.g. 2454 * migrate_pages 2455 */ 2456 lru_add_page_tail(head, page_tail, lruvec, list); 2457 } 2458 2459 static void __split_huge_page(struct page *page, struct list_head *list, 2460 pgoff_t end) 2461 { 2462 struct page *head = compound_head(page); 2463 struct lruvec *lruvec; 2464 struct address_space *swap_cache = NULL; 2465 unsigned long offset = 0; 2466 unsigned int nr = thp_nr_pages(head); 2467 int i; 2468 2469 /* complete memcg works before add pages to LRU */ 2470 split_page_memcg(head, nr); 2471 2472 if (PageAnon(head) && PageSwapCache(head)) { 2473 swp_entry_t entry = { .val = page_private(head) }; 2474 2475 offset = swp_offset(entry); 2476 swap_cache = swap_address_space(entry); 2477 xa_lock(&swap_cache->i_pages); 2478 } 2479 2480 /* lock lru list/PageCompound, ref freezed by page_ref_freeze */ 2481 lruvec = lock_page_lruvec(head); 2482 2483 for (i = nr - 1; i >= 1; i--) { 2484 __split_huge_page_tail(head, i, lruvec, list); 2485 /* Some pages can be beyond i_size: drop them from page cache */ 2486 if (head[i].index >= end) { 2487 ClearPageDirty(head + i); 2488 __delete_from_page_cache(head + i, NULL); 2489 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) 2490 shmem_uncharge(head->mapping->host, 1); 2491 put_page(head + i); 2492 } else if (!PageAnon(page)) { 2493 __xa_store(&head->mapping->i_pages, head[i].index, 2494 head + i, 0); 2495 } else if (swap_cache) { 2496 __xa_store(&swap_cache->i_pages, offset + i, 2497 head + i, 0); 2498 } 2499 } 2500 2501 ClearPageCompound(head); 2502 unlock_page_lruvec(lruvec); 2503 /* Caller disabled irqs, so they are still disabled here */ 2504 2505 split_page_owner(head, nr); 2506 2507 /* See comment in __split_huge_page_tail() */ 2508 if (PageAnon(head)) { 2509 /* Additional pin to swap cache */ 2510 if (PageSwapCache(head)) { 2511 page_ref_add(head, 2); 2512 xa_unlock(&swap_cache->i_pages); 2513 } else { 2514 page_ref_inc(head); 2515 } 2516 } else { 2517 /* Additional pin to page cache */ 2518 page_ref_add(head, 2); 2519 xa_unlock(&head->mapping->i_pages); 2520 } 2521 local_irq_enable(); 2522 2523 remap_page(head, nr); 2524 2525 if (PageSwapCache(head)) { 2526 swp_entry_t entry = { .val = page_private(head) }; 2527 2528 split_swap_cluster(entry); 2529 } 2530 2531 for (i = 0; i < nr; i++) { 2532 struct page *subpage = head + i; 2533 if (subpage == page) 2534 continue; 2535 unlock_page(subpage); 2536 2537 /* 2538 * Subpages may be freed if there wasn't any mapping 2539 * like if add_to_swap() is running on a lru page that 2540 * had its mapping zapped. And freeing these pages 2541 * requires taking the lru_lock so we do the put_page 2542 * of the tail pages after the split is complete. 2543 */ 2544 put_page(subpage); 2545 } 2546 } 2547 2548 int total_mapcount(struct page *page) 2549 { 2550 int i, compound, nr, ret; 2551 2552 VM_BUG_ON_PAGE(PageTail(page), page); 2553 2554 if (likely(!PageCompound(page))) 2555 return atomic_read(&page->_mapcount) + 1; 2556 2557 compound = compound_mapcount(page); 2558 nr = compound_nr(page); 2559 if (PageHuge(page)) 2560 return compound; 2561 ret = compound; 2562 for (i = 0; i < nr; i++) 2563 ret += atomic_read(&page[i]._mapcount) + 1; 2564 /* File pages has compound_mapcount included in _mapcount */ 2565 if (!PageAnon(page)) 2566 return ret - compound * nr; 2567 if (PageDoubleMap(page)) 2568 ret -= nr; 2569 return ret; 2570 } 2571 2572 /* 2573 * This calculates accurately how many mappings a transparent hugepage 2574 * has (unlike page_mapcount() which isn't fully accurate). This full 2575 * accuracy is primarily needed to know if copy-on-write faults can 2576 * reuse the page and change the mapping to read-write instead of 2577 * copying them. At the same time this returns the total_mapcount too. 2578 * 2579 * The function returns the highest mapcount any one of the subpages 2580 * has. If the return value is one, even if different processes are 2581 * mapping different subpages of the transparent hugepage, they can 2582 * all reuse it, because each process is reusing a different subpage. 2583 * 2584 * The total_mapcount is instead counting all virtual mappings of the 2585 * subpages. If the total_mapcount is equal to "one", it tells the 2586 * caller all mappings belong to the same "mm" and in turn the 2587 * anon_vma of the transparent hugepage can become the vma->anon_vma 2588 * local one as no other process may be mapping any of the subpages. 2589 * 2590 * It would be more accurate to replace page_mapcount() with 2591 * page_trans_huge_mapcount(), however we only use 2592 * page_trans_huge_mapcount() in the copy-on-write faults where we 2593 * need full accuracy to avoid breaking page pinning, because 2594 * page_trans_huge_mapcount() is slower than page_mapcount(). 2595 */ 2596 int page_trans_huge_mapcount(struct page *page, int *total_mapcount) 2597 { 2598 int i, ret, _total_mapcount, mapcount; 2599 2600 /* hugetlbfs shouldn't call it */ 2601 VM_BUG_ON_PAGE(PageHuge(page), page); 2602 2603 if (likely(!PageTransCompound(page))) { 2604 mapcount = atomic_read(&page->_mapcount) + 1; 2605 if (total_mapcount) 2606 *total_mapcount = mapcount; 2607 return mapcount; 2608 } 2609 2610 page = compound_head(page); 2611 2612 _total_mapcount = ret = 0; 2613 for (i = 0; i < thp_nr_pages(page); i++) { 2614 mapcount = atomic_read(&page[i]._mapcount) + 1; 2615 ret = max(ret, mapcount); 2616 _total_mapcount += mapcount; 2617 } 2618 if (PageDoubleMap(page)) { 2619 ret -= 1; 2620 _total_mapcount -= thp_nr_pages(page); 2621 } 2622 mapcount = compound_mapcount(page); 2623 ret += mapcount; 2624 _total_mapcount += mapcount; 2625 if (total_mapcount) 2626 *total_mapcount = _total_mapcount; 2627 return ret; 2628 } 2629 2630 /* Racy check whether the huge page can be split */ 2631 bool can_split_huge_page(struct page *page, int *pextra_pins) 2632 { 2633 int extra_pins; 2634 2635 /* Additional pins from page cache */ 2636 if (PageAnon(page)) 2637 extra_pins = PageSwapCache(page) ? thp_nr_pages(page) : 0; 2638 else 2639 extra_pins = thp_nr_pages(page); 2640 if (pextra_pins) 2641 *pextra_pins = extra_pins; 2642 return total_mapcount(page) == page_count(page) - extra_pins - 1; 2643 } 2644 2645 /* 2646 * This function splits huge page into normal pages. @page can point to any 2647 * subpage of huge page to split. Split doesn't change the position of @page. 2648 * 2649 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2650 * The huge page must be locked. 2651 * 2652 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2653 * 2654 * Both head page and tail pages will inherit mapping, flags, and so on from 2655 * the hugepage. 2656 * 2657 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2658 * they are not mapped. 2659 * 2660 * Returns 0 if the hugepage is split successfully. 2661 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2662 * us. 2663 */ 2664 int split_huge_page_to_list(struct page *page, struct list_head *list) 2665 { 2666 struct page *head = compound_head(page); 2667 struct deferred_split *ds_queue = get_deferred_split_queue(head); 2668 struct anon_vma *anon_vma = NULL; 2669 struct address_space *mapping = NULL; 2670 int count, mapcount, extra_pins, ret; 2671 pgoff_t end; 2672 2673 VM_BUG_ON_PAGE(is_huge_zero_page(head), head); 2674 VM_BUG_ON_PAGE(!PageLocked(head), head); 2675 VM_BUG_ON_PAGE(!PageCompound(head), head); 2676 2677 if (PageWriteback(head)) 2678 return -EBUSY; 2679 2680 if (PageAnon(head)) { 2681 /* 2682 * The caller does not necessarily hold an mmap_lock that would 2683 * prevent the anon_vma disappearing so we first we take a 2684 * reference to it and then lock the anon_vma for write. This 2685 * is similar to page_lock_anon_vma_read except the write lock 2686 * is taken to serialise against parallel split or collapse 2687 * operations. 2688 */ 2689 anon_vma = page_get_anon_vma(head); 2690 if (!anon_vma) { 2691 ret = -EBUSY; 2692 goto out; 2693 } 2694 end = -1; 2695 mapping = NULL; 2696 anon_vma_lock_write(anon_vma); 2697 } else { 2698 mapping = head->mapping; 2699 2700 /* Truncated ? */ 2701 if (!mapping) { 2702 ret = -EBUSY; 2703 goto out; 2704 } 2705 2706 anon_vma = NULL; 2707 i_mmap_lock_read(mapping); 2708 2709 /* 2710 *__split_huge_page() may need to trim off pages beyond EOF: 2711 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2712 * which cannot be nested inside the page tree lock. So note 2713 * end now: i_size itself may be changed at any moment, but 2714 * head page lock is good enough to serialize the trimming. 2715 */ 2716 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2717 } 2718 2719 /* 2720 * Racy check if we can split the page, before unmap_page() will 2721 * split PMDs 2722 */ 2723 if (!can_split_huge_page(head, &extra_pins)) { 2724 ret = -EBUSY; 2725 goto out_unlock; 2726 } 2727 2728 unmap_page(head); 2729 VM_BUG_ON_PAGE(compound_mapcount(head), head); 2730 2731 /* block interrupt reentry in xa_lock and spinlock */ 2732 local_irq_disable(); 2733 if (mapping) { 2734 XA_STATE(xas, &mapping->i_pages, page_index(head)); 2735 2736 /* 2737 * Check if the head page is present in page cache. 2738 * We assume all tail are present too, if head is there. 2739 */ 2740 xa_lock(&mapping->i_pages); 2741 if (xas_load(&xas) != head) 2742 goto fail; 2743 } 2744 2745 /* Prevent deferred_split_scan() touching ->_refcount */ 2746 spin_lock(&ds_queue->split_queue_lock); 2747 count = page_count(head); 2748 mapcount = total_mapcount(head); 2749 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) { 2750 if (!list_empty(page_deferred_list(head))) { 2751 ds_queue->split_queue_len--; 2752 list_del(page_deferred_list(head)); 2753 } 2754 spin_unlock(&ds_queue->split_queue_lock); 2755 if (mapping) { 2756 int nr = thp_nr_pages(head); 2757 2758 if (PageSwapBacked(head)) 2759 __mod_lruvec_page_state(head, NR_SHMEM_THPS, 2760 -nr); 2761 else 2762 __mod_lruvec_page_state(head, NR_FILE_THPS, 2763 -nr); 2764 } 2765 2766 __split_huge_page(page, list, end); 2767 ret = 0; 2768 } else { 2769 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { 2770 pr_alert("total_mapcount: %u, page_count(): %u\n", 2771 mapcount, count); 2772 if (PageTail(page)) 2773 dump_page(head, NULL); 2774 dump_page(page, "total_mapcount(head) > 0"); 2775 BUG(); 2776 } 2777 spin_unlock(&ds_queue->split_queue_lock); 2778 fail: if (mapping) 2779 xa_unlock(&mapping->i_pages); 2780 local_irq_enable(); 2781 remap_page(head, thp_nr_pages(head)); 2782 ret = -EBUSY; 2783 } 2784 2785 out_unlock: 2786 if (anon_vma) { 2787 anon_vma_unlock_write(anon_vma); 2788 put_anon_vma(anon_vma); 2789 } 2790 if (mapping) 2791 i_mmap_unlock_read(mapping); 2792 out: 2793 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2794 return ret; 2795 } 2796 2797 void free_transhuge_page(struct page *page) 2798 { 2799 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2800 unsigned long flags; 2801 2802 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2803 if (!list_empty(page_deferred_list(page))) { 2804 ds_queue->split_queue_len--; 2805 list_del(page_deferred_list(page)); 2806 } 2807 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2808 free_compound_page(page); 2809 } 2810 2811 void deferred_split_huge_page(struct page *page) 2812 { 2813 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2814 #ifdef CONFIG_MEMCG 2815 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 2816 #endif 2817 unsigned long flags; 2818 2819 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2820 2821 /* 2822 * The try_to_unmap() in page reclaim path might reach here too, 2823 * this may cause a race condition to corrupt deferred split queue. 2824 * And, if page reclaim is already handling the same page, it is 2825 * unnecessary to handle it again in shrinker. 2826 * 2827 * Check PageSwapCache to determine if the page is being 2828 * handled by page reclaim since THP swap would add the page into 2829 * swap cache before calling try_to_unmap(). 2830 */ 2831 if (PageSwapCache(page)) 2832 return; 2833 2834 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2835 if (list_empty(page_deferred_list(page))) { 2836 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2837 list_add_tail(page_deferred_list(page), &ds_queue->split_queue); 2838 ds_queue->split_queue_len++; 2839 #ifdef CONFIG_MEMCG 2840 if (memcg) 2841 memcg_set_shrinker_bit(memcg, page_to_nid(page), 2842 deferred_split_shrinker.id); 2843 #endif 2844 } 2845 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2846 } 2847 2848 static unsigned long deferred_split_count(struct shrinker *shrink, 2849 struct shrink_control *sc) 2850 { 2851 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2852 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2853 2854 #ifdef CONFIG_MEMCG 2855 if (sc->memcg) 2856 ds_queue = &sc->memcg->deferred_split_queue; 2857 #endif 2858 return READ_ONCE(ds_queue->split_queue_len); 2859 } 2860 2861 static unsigned long deferred_split_scan(struct shrinker *shrink, 2862 struct shrink_control *sc) 2863 { 2864 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2865 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2866 unsigned long flags; 2867 LIST_HEAD(list), *pos, *next; 2868 struct page *page; 2869 int split = 0; 2870 2871 #ifdef CONFIG_MEMCG 2872 if (sc->memcg) 2873 ds_queue = &sc->memcg->deferred_split_queue; 2874 #endif 2875 2876 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2877 /* Take pin on all head pages to avoid freeing them under us */ 2878 list_for_each_safe(pos, next, &ds_queue->split_queue) { 2879 page = list_entry((void *)pos, struct page, mapping); 2880 page = compound_head(page); 2881 if (get_page_unless_zero(page)) { 2882 list_move(page_deferred_list(page), &list); 2883 } else { 2884 /* We lost race with put_compound_page() */ 2885 list_del_init(page_deferred_list(page)); 2886 ds_queue->split_queue_len--; 2887 } 2888 if (!--sc->nr_to_scan) 2889 break; 2890 } 2891 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2892 2893 list_for_each_safe(pos, next, &list) { 2894 page = list_entry((void *)pos, struct page, mapping); 2895 if (!trylock_page(page)) 2896 goto next; 2897 /* split_huge_page() removes page from list on success */ 2898 if (!split_huge_page(page)) 2899 split++; 2900 unlock_page(page); 2901 next: 2902 put_page(page); 2903 } 2904 2905 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2906 list_splice_tail(&list, &ds_queue->split_queue); 2907 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2908 2909 /* 2910 * Stop shrinker if we didn't split any page, but the queue is empty. 2911 * This can happen if pages were freed under us. 2912 */ 2913 if (!split && list_empty(&ds_queue->split_queue)) 2914 return SHRINK_STOP; 2915 return split; 2916 } 2917 2918 static struct shrinker deferred_split_shrinker = { 2919 .count_objects = deferred_split_count, 2920 .scan_objects = deferred_split_scan, 2921 .seeks = DEFAULT_SEEKS, 2922 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | 2923 SHRINKER_NONSLAB, 2924 }; 2925 2926 #ifdef CONFIG_DEBUG_FS 2927 static int split_huge_pages_set(void *data, u64 val) 2928 { 2929 struct zone *zone; 2930 struct page *page; 2931 unsigned long pfn, max_zone_pfn; 2932 unsigned long total = 0, split = 0; 2933 2934 if (val != 1) 2935 return -EINVAL; 2936 2937 for_each_populated_zone(zone) { 2938 max_zone_pfn = zone_end_pfn(zone); 2939 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2940 if (!pfn_valid(pfn)) 2941 continue; 2942 2943 page = pfn_to_page(pfn); 2944 if (!get_page_unless_zero(page)) 2945 continue; 2946 2947 if (zone != page_zone(page)) 2948 goto next; 2949 2950 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 2951 goto next; 2952 2953 total++; 2954 lock_page(page); 2955 if (!split_huge_page(page)) 2956 split++; 2957 unlock_page(page); 2958 next: 2959 put_page(page); 2960 } 2961 } 2962 2963 pr_info("%lu of %lu THP split\n", split, total); 2964 2965 return 0; 2966 } 2967 DEFINE_DEBUGFS_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, 2968 "%llu\n"); 2969 2970 static int __init split_huge_pages_debugfs(void) 2971 { 2972 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 2973 &split_huge_pages_fops); 2974 return 0; 2975 } 2976 late_initcall(split_huge_pages_debugfs); 2977 #endif 2978 2979 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 2980 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 2981 struct page *page) 2982 { 2983 struct vm_area_struct *vma = pvmw->vma; 2984 struct mm_struct *mm = vma->vm_mm; 2985 unsigned long address = pvmw->address; 2986 pmd_t pmdval; 2987 swp_entry_t entry; 2988 pmd_t pmdswp; 2989 2990 if (!(pvmw->pmd && !pvmw->pte)) 2991 return; 2992 2993 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 2994 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 2995 if (pmd_dirty(pmdval)) 2996 set_page_dirty(page); 2997 entry = make_migration_entry(page, pmd_write(pmdval)); 2998 pmdswp = swp_entry_to_pmd(entry); 2999 if (pmd_soft_dirty(pmdval)) 3000 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3001 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3002 page_remove_rmap(page, true); 3003 put_page(page); 3004 } 3005 3006 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3007 { 3008 struct vm_area_struct *vma = pvmw->vma; 3009 struct mm_struct *mm = vma->vm_mm; 3010 unsigned long address = pvmw->address; 3011 unsigned long mmun_start = address & HPAGE_PMD_MASK; 3012 pmd_t pmde; 3013 swp_entry_t entry; 3014 3015 if (!(pvmw->pmd && !pvmw->pte)) 3016 return; 3017 3018 entry = pmd_to_swp_entry(*pvmw->pmd); 3019 get_page(new); 3020 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot)); 3021 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3022 pmde = pmd_mksoft_dirty(pmde); 3023 if (is_write_migration_entry(entry)) 3024 pmde = maybe_pmd_mkwrite(pmde, vma); 3025 3026 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE); 3027 if (PageAnon(new)) 3028 page_add_anon_rmap(new, vma, mmun_start, true); 3029 else 3030 page_add_file_rmap(new, true); 3031 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde); 3032 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new)) 3033 mlock_vma_page(new); 3034 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3035 } 3036 #endif 3037