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/mm.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/backing-dev.h> 21 #include <linux/dax.h> 22 #include <linux/mm_types.h> 23 #include <linux/khugepaged.h> 24 #include <linux/freezer.h> 25 #include <linux/pfn_t.h> 26 #include <linux/mman.h> 27 #include <linux/memremap.h> 28 #include <linux/pagemap.h> 29 #include <linux/debugfs.h> 30 #include <linux/migrate.h> 31 #include <linux/hashtable.h> 32 #include <linux/userfaultfd_k.h> 33 #include <linux/page_idle.h> 34 #include <linux/shmem_fs.h> 35 #include <linux/oom.h> 36 #include <linux/numa.h> 37 #include <linux/page_owner.h> 38 #include <linux/sched/sysctl.h> 39 #include <linux/memory-tiers.h> 40 #include <linux/compat.h> 41 #include <linux/pgalloc_tag.h> 42 #include <linux/pagewalk.h> 43 44 #include <asm/tlb.h> 45 #include <asm/pgalloc.h> 46 #include "internal.h" 47 #include "swap.h" 48 49 #define CREATE_TRACE_POINTS 50 #include <trace/events/thp.h> 51 52 /* 53 * By default, transparent hugepage support is disabled in order to avoid 54 * risking an increased memory footprint for applications that are not 55 * guaranteed to benefit from it. When transparent hugepage support is 56 * enabled, it is for all mappings, and khugepaged scans all mappings. 57 * Defrag is invoked by khugepaged hugepage allocations and by page faults 58 * for all hugepage allocations. 59 */ 60 unsigned long transparent_hugepage_flags __read_mostly = 61 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 62 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 63 #endif 64 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 65 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 66 #endif 67 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 68 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 69 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 70 71 static struct shrinker *deferred_split_shrinker; 72 static unsigned long deferred_split_count(struct shrinker *shrink, 73 struct shrink_control *sc); 74 static unsigned long deferred_split_scan(struct shrinker *shrink, 75 struct shrink_control *sc); 76 static bool split_underused_thp = true; 77 78 static atomic_t huge_zero_refcount; 79 struct folio *huge_zero_folio __read_mostly; 80 unsigned long huge_zero_pfn __read_mostly = ~0UL; 81 unsigned long huge_anon_orders_always __read_mostly; 82 unsigned long huge_anon_orders_madvise __read_mostly; 83 unsigned long huge_anon_orders_inherit __read_mostly; 84 static bool anon_orders_configured __initdata; 85 86 static inline bool file_thp_enabled(struct vm_area_struct *vma) 87 { 88 struct inode *inode; 89 90 if (!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) 91 return false; 92 93 if (!vma->vm_file) 94 return false; 95 96 inode = file_inode(vma->vm_file); 97 98 return !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode); 99 } 100 101 unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, 102 unsigned long vm_flags, 103 unsigned long tva_flags, 104 unsigned long orders) 105 { 106 bool smaps = tva_flags & TVA_SMAPS; 107 bool in_pf = tva_flags & TVA_IN_PF; 108 bool enforce_sysfs = tva_flags & TVA_ENFORCE_SYSFS; 109 unsigned long supported_orders; 110 111 /* Check the intersection of requested and supported orders. */ 112 if (vma_is_anonymous(vma)) 113 supported_orders = THP_ORDERS_ALL_ANON; 114 else if (vma_is_special_huge(vma)) 115 supported_orders = THP_ORDERS_ALL_SPECIAL; 116 else 117 supported_orders = THP_ORDERS_ALL_FILE_DEFAULT; 118 119 orders &= supported_orders; 120 if (!orders) 121 return 0; 122 123 if (!vma->vm_mm) /* vdso */ 124 return 0; 125 126 if (thp_disabled_by_hw() || vma_thp_disabled(vma, vm_flags)) 127 return 0; 128 129 /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ 130 if (vma_is_dax(vma)) 131 return in_pf ? orders : 0; 132 133 /* 134 * khugepaged special VMA and hugetlb VMA. 135 * Must be checked after dax since some dax mappings may have 136 * VM_MIXEDMAP set. 137 */ 138 if (!in_pf && !smaps && (vm_flags & VM_NO_KHUGEPAGED)) 139 return 0; 140 141 /* 142 * Check alignment for file vma and size for both file and anon vma by 143 * filtering out the unsuitable orders. 144 * 145 * Skip the check for page fault. Huge fault does the check in fault 146 * handlers. 147 */ 148 if (!in_pf) { 149 int order = highest_order(orders); 150 unsigned long addr; 151 152 while (orders) { 153 addr = vma->vm_end - (PAGE_SIZE << order); 154 if (thp_vma_suitable_order(vma, addr, order)) 155 break; 156 order = next_order(&orders, order); 157 } 158 159 if (!orders) 160 return 0; 161 } 162 163 /* 164 * Enabled via shmem mount options or sysfs settings. 165 * Must be done before hugepage flags check since shmem has its 166 * own flags. 167 */ 168 if (!in_pf && shmem_file(vma->vm_file)) 169 return shmem_allowable_huge_orders(file_inode(vma->vm_file), 170 vma, vma->vm_pgoff, 0, 171 !enforce_sysfs); 172 173 if (!vma_is_anonymous(vma)) { 174 /* 175 * Enforce sysfs THP requirements as necessary. Anonymous vmas 176 * were already handled in thp_vma_allowable_orders(). 177 */ 178 if (enforce_sysfs && 179 (!hugepage_global_enabled() || (!(vm_flags & VM_HUGEPAGE) && 180 !hugepage_global_always()))) 181 return 0; 182 183 /* 184 * Trust that ->huge_fault() handlers know what they are doing 185 * in fault path. 186 */ 187 if (((in_pf || smaps)) && vma->vm_ops->huge_fault) 188 return orders; 189 /* Only regular file is valid in collapse path */ 190 if (((!in_pf || smaps)) && file_thp_enabled(vma)) 191 return orders; 192 return 0; 193 } 194 195 if (vma_is_temporary_stack(vma)) 196 return 0; 197 198 /* 199 * THPeligible bit of smaps should show 1 for proper VMAs even 200 * though anon_vma is not initialized yet. 201 * 202 * Allow page fault since anon_vma may be not initialized until 203 * the first page fault. 204 */ 205 if (!vma->anon_vma) 206 return (smaps || in_pf) ? orders : 0; 207 208 return orders; 209 } 210 211 static bool get_huge_zero_page(void) 212 { 213 struct folio *zero_folio; 214 retry: 215 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 216 return true; 217 218 zero_folio = folio_alloc((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 219 HPAGE_PMD_ORDER); 220 if (!zero_folio) { 221 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 222 return false; 223 } 224 /* Ensure zero folio won't have large_rmappable flag set. */ 225 folio_clear_large_rmappable(zero_folio); 226 preempt_disable(); 227 if (cmpxchg(&huge_zero_folio, NULL, zero_folio)) { 228 preempt_enable(); 229 folio_put(zero_folio); 230 goto retry; 231 } 232 WRITE_ONCE(huge_zero_pfn, folio_pfn(zero_folio)); 233 234 /* We take additional reference here. It will be put back by shrinker */ 235 atomic_set(&huge_zero_refcount, 2); 236 preempt_enable(); 237 count_vm_event(THP_ZERO_PAGE_ALLOC); 238 return true; 239 } 240 241 static void put_huge_zero_page(void) 242 { 243 /* 244 * Counter should never go to zero here. Only shrinker can put 245 * last reference. 246 */ 247 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 248 } 249 250 struct folio *mm_get_huge_zero_folio(struct mm_struct *mm) 251 { 252 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 253 return READ_ONCE(huge_zero_folio); 254 255 if (!get_huge_zero_page()) 256 return NULL; 257 258 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 259 put_huge_zero_page(); 260 261 return READ_ONCE(huge_zero_folio); 262 } 263 264 void mm_put_huge_zero_folio(struct mm_struct *mm) 265 { 266 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 267 put_huge_zero_page(); 268 } 269 270 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 271 struct shrink_control *sc) 272 { 273 /* we can free zero page only if last reference remains */ 274 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 275 } 276 277 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 278 struct shrink_control *sc) 279 { 280 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 281 struct folio *zero_folio = xchg(&huge_zero_folio, NULL); 282 BUG_ON(zero_folio == NULL); 283 WRITE_ONCE(huge_zero_pfn, ~0UL); 284 folio_put(zero_folio); 285 return HPAGE_PMD_NR; 286 } 287 288 return 0; 289 } 290 291 static struct shrinker *huge_zero_page_shrinker; 292 293 #ifdef CONFIG_SYSFS 294 static ssize_t enabled_show(struct kobject *kobj, 295 struct kobj_attribute *attr, char *buf) 296 { 297 const char *output; 298 299 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 300 output = "[always] madvise never"; 301 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 302 &transparent_hugepage_flags)) 303 output = "always [madvise] never"; 304 else 305 output = "always madvise [never]"; 306 307 return sysfs_emit(buf, "%s\n", output); 308 } 309 310 static ssize_t enabled_store(struct kobject *kobj, 311 struct kobj_attribute *attr, 312 const char *buf, size_t count) 313 { 314 ssize_t ret = count; 315 316 if (sysfs_streq(buf, "always")) { 317 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 318 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 319 } else if (sysfs_streq(buf, "madvise")) { 320 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 321 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 322 } else if (sysfs_streq(buf, "never")) { 323 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 324 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 325 } else 326 ret = -EINVAL; 327 328 if (ret > 0) { 329 int err = start_stop_khugepaged(); 330 if (err) 331 ret = err; 332 } 333 return ret; 334 } 335 336 static struct kobj_attribute enabled_attr = __ATTR_RW(enabled); 337 338 ssize_t single_hugepage_flag_show(struct kobject *kobj, 339 struct kobj_attribute *attr, char *buf, 340 enum transparent_hugepage_flag flag) 341 { 342 return sysfs_emit(buf, "%d\n", 343 !!test_bit(flag, &transparent_hugepage_flags)); 344 } 345 346 ssize_t single_hugepage_flag_store(struct kobject *kobj, 347 struct kobj_attribute *attr, 348 const char *buf, size_t count, 349 enum transparent_hugepage_flag flag) 350 { 351 unsigned long value; 352 int ret; 353 354 ret = kstrtoul(buf, 10, &value); 355 if (ret < 0) 356 return ret; 357 if (value > 1) 358 return -EINVAL; 359 360 if (value) 361 set_bit(flag, &transparent_hugepage_flags); 362 else 363 clear_bit(flag, &transparent_hugepage_flags); 364 365 return count; 366 } 367 368 static ssize_t defrag_show(struct kobject *kobj, 369 struct kobj_attribute *attr, char *buf) 370 { 371 const char *output; 372 373 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 374 &transparent_hugepage_flags)) 375 output = "[always] defer defer+madvise madvise never"; 376 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 377 &transparent_hugepage_flags)) 378 output = "always [defer] defer+madvise madvise never"; 379 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 380 &transparent_hugepage_flags)) 381 output = "always defer [defer+madvise] madvise never"; 382 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 383 &transparent_hugepage_flags)) 384 output = "always defer defer+madvise [madvise] never"; 385 else 386 output = "always defer defer+madvise madvise [never]"; 387 388 return sysfs_emit(buf, "%s\n", output); 389 } 390 391 static ssize_t defrag_store(struct kobject *kobj, 392 struct kobj_attribute *attr, 393 const char *buf, size_t count) 394 { 395 if (sysfs_streq(buf, "always")) { 396 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 397 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 398 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 399 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 400 } else if (sysfs_streq(buf, "defer+madvise")) { 401 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 402 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 403 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 404 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 405 } else if (sysfs_streq(buf, "defer")) { 406 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 407 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 408 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 409 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 410 } else if (sysfs_streq(buf, "madvise")) { 411 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 412 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 413 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 414 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 415 } else if (sysfs_streq(buf, "never")) { 416 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 417 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 418 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 419 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 420 } else 421 return -EINVAL; 422 423 return count; 424 } 425 static struct kobj_attribute defrag_attr = __ATTR_RW(defrag); 426 427 static ssize_t use_zero_page_show(struct kobject *kobj, 428 struct kobj_attribute *attr, char *buf) 429 { 430 return single_hugepage_flag_show(kobj, attr, buf, 431 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 432 } 433 static ssize_t use_zero_page_store(struct kobject *kobj, 434 struct kobj_attribute *attr, const char *buf, size_t count) 435 { 436 return single_hugepage_flag_store(kobj, attr, buf, count, 437 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 438 } 439 static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page); 440 441 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 442 struct kobj_attribute *attr, char *buf) 443 { 444 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); 445 } 446 static struct kobj_attribute hpage_pmd_size_attr = 447 __ATTR_RO(hpage_pmd_size); 448 449 static ssize_t split_underused_thp_show(struct kobject *kobj, 450 struct kobj_attribute *attr, char *buf) 451 { 452 return sysfs_emit(buf, "%d\n", split_underused_thp); 453 } 454 455 static ssize_t split_underused_thp_store(struct kobject *kobj, 456 struct kobj_attribute *attr, 457 const char *buf, size_t count) 458 { 459 int err = kstrtobool(buf, &split_underused_thp); 460 461 if (err < 0) 462 return err; 463 464 return count; 465 } 466 467 static struct kobj_attribute split_underused_thp_attr = __ATTR( 468 shrink_underused, 0644, split_underused_thp_show, split_underused_thp_store); 469 470 static struct attribute *hugepage_attr[] = { 471 &enabled_attr.attr, 472 &defrag_attr.attr, 473 &use_zero_page_attr.attr, 474 &hpage_pmd_size_attr.attr, 475 #ifdef CONFIG_SHMEM 476 &shmem_enabled_attr.attr, 477 #endif 478 &split_underused_thp_attr.attr, 479 NULL, 480 }; 481 482 static const struct attribute_group hugepage_attr_group = { 483 .attrs = hugepage_attr, 484 }; 485 486 static void hugepage_exit_sysfs(struct kobject *hugepage_kobj); 487 static void thpsize_release(struct kobject *kobj); 488 static DEFINE_SPINLOCK(huge_anon_orders_lock); 489 static LIST_HEAD(thpsize_list); 490 491 static ssize_t anon_enabled_show(struct kobject *kobj, 492 struct kobj_attribute *attr, char *buf) 493 { 494 int order = to_thpsize(kobj)->order; 495 const char *output; 496 497 if (test_bit(order, &huge_anon_orders_always)) 498 output = "[always] inherit madvise never"; 499 else if (test_bit(order, &huge_anon_orders_inherit)) 500 output = "always [inherit] madvise never"; 501 else if (test_bit(order, &huge_anon_orders_madvise)) 502 output = "always inherit [madvise] never"; 503 else 504 output = "always inherit madvise [never]"; 505 506 return sysfs_emit(buf, "%s\n", output); 507 } 508 509 static ssize_t anon_enabled_store(struct kobject *kobj, 510 struct kobj_attribute *attr, 511 const char *buf, size_t count) 512 { 513 int order = to_thpsize(kobj)->order; 514 ssize_t ret = count; 515 516 if (sysfs_streq(buf, "always")) { 517 spin_lock(&huge_anon_orders_lock); 518 clear_bit(order, &huge_anon_orders_inherit); 519 clear_bit(order, &huge_anon_orders_madvise); 520 set_bit(order, &huge_anon_orders_always); 521 spin_unlock(&huge_anon_orders_lock); 522 } else if (sysfs_streq(buf, "inherit")) { 523 spin_lock(&huge_anon_orders_lock); 524 clear_bit(order, &huge_anon_orders_always); 525 clear_bit(order, &huge_anon_orders_madvise); 526 set_bit(order, &huge_anon_orders_inherit); 527 spin_unlock(&huge_anon_orders_lock); 528 } else if (sysfs_streq(buf, "madvise")) { 529 spin_lock(&huge_anon_orders_lock); 530 clear_bit(order, &huge_anon_orders_always); 531 clear_bit(order, &huge_anon_orders_inherit); 532 set_bit(order, &huge_anon_orders_madvise); 533 spin_unlock(&huge_anon_orders_lock); 534 } else if (sysfs_streq(buf, "never")) { 535 spin_lock(&huge_anon_orders_lock); 536 clear_bit(order, &huge_anon_orders_always); 537 clear_bit(order, &huge_anon_orders_inherit); 538 clear_bit(order, &huge_anon_orders_madvise); 539 spin_unlock(&huge_anon_orders_lock); 540 } else 541 ret = -EINVAL; 542 543 if (ret > 0) { 544 int err; 545 546 err = start_stop_khugepaged(); 547 if (err) 548 ret = err; 549 } 550 return ret; 551 } 552 553 static struct kobj_attribute anon_enabled_attr = 554 __ATTR(enabled, 0644, anon_enabled_show, anon_enabled_store); 555 556 static struct attribute *anon_ctrl_attrs[] = { 557 &anon_enabled_attr.attr, 558 NULL, 559 }; 560 561 static const struct attribute_group anon_ctrl_attr_grp = { 562 .attrs = anon_ctrl_attrs, 563 }; 564 565 static struct attribute *file_ctrl_attrs[] = { 566 #ifdef CONFIG_SHMEM 567 &thpsize_shmem_enabled_attr.attr, 568 #endif 569 NULL, 570 }; 571 572 static const struct attribute_group file_ctrl_attr_grp = { 573 .attrs = file_ctrl_attrs, 574 }; 575 576 static struct attribute *any_ctrl_attrs[] = { 577 NULL, 578 }; 579 580 static const struct attribute_group any_ctrl_attr_grp = { 581 .attrs = any_ctrl_attrs, 582 }; 583 584 static const struct kobj_type thpsize_ktype = { 585 .release = &thpsize_release, 586 .sysfs_ops = &kobj_sysfs_ops, 587 }; 588 589 DEFINE_PER_CPU(struct mthp_stat, mthp_stats) = {{{0}}}; 590 591 static unsigned long sum_mthp_stat(int order, enum mthp_stat_item item) 592 { 593 unsigned long sum = 0; 594 int cpu; 595 596 for_each_possible_cpu(cpu) { 597 struct mthp_stat *this = &per_cpu(mthp_stats, cpu); 598 599 sum += this->stats[order][item]; 600 } 601 602 return sum; 603 } 604 605 #define DEFINE_MTHP_STAT_ATTR(_name, _index) \ 606 static ssize_t _name##_show(struct kobject *kobj, \ 607 struct kobj_attribute *attr, char *buf) \ 608 { \ 609 int order = to_thpsize(kobj)->order; \ 610 \ 611 return sysfs_emit(buf, "%lu\n", sum_mthp_stat(order, _index)); \ 612 } \ 613 static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 614 615 DEFINE_MTHP_STAT_ATTR(anon_fault_alloc, MTHP_STAT_ANON_FAULT_ALLOC); 616 DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK); 617 DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); 618 DEFINE_MTHP_STAT_ATTR(zswpout, MTHP_STAT_ZSWPOUT); 619 DEFINE_MTHP_STAT_ATTR(swpin, MTHP_STAT_SWPIN); 620 DEFINE_MTHP_STAT_ATTR(swpin_fallback, MTHP_STAT_SWPIN_FALLBACK); 621 DEFINE_MTHP_STAT_ATTR(swpin_fallback_charge, MTHP_STAT_SWPIN_FALLBACK_CHARGE); 622 DEFINE_MTHP_STAT_ATTR(swpout, MTHP_STAT_SWPOUT); 623 DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK); 624 #ifdef CONFIG_SHMEM 625 DEFINE_MTHP_STAT_ATTR(shmem_alloc, MTHP_STAT_SHMEM_ALLOC); 626 DEFINE_MTHP_STAT_ATTR(shmem_fallback, MTHP_STAT_SHMEM_FALLBACK); 627 DEFINE_MTHP_STAT_ATTR(shmem_fallback_charge, MTHP_STAT_SHMEM_FALLBACK_CHARGE); 628 #endif 629 DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT); 630 DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED); 631 DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED); 632 DEFINE_MTHP_STAT_ATTR(nr_anon, MTHP_STAT_NR_ANON); 633 DEFINE_MTHP_STAT_ATTR(nr_anon_partially_mapped, MTHP_STAT_NR_ANON_PARTIALLY_MAPPED); 634 635 static struct attribute *anon_stats_attrs[] = { 636 &anon_fault_alloc_attr.attr, 637 &anon_fault_fallback_attr.attr, 638 &anon_fault_fallback_charge_attr.attr, 639 #ifndef CONFIG_SHMEM 640 &zswpout_attr.attr, 641 &swpin_attr.attr, 642 &swpin_fallback_attr.attr, 643 &swpin_fallback_charge_attr.attr, 644 &swpout_attr.attr, 645 &swpout_fallback_attr.attr, 646 #endif 647 &split_deferred_attr.attr, 648 &nr_anon_attr.attr, 649 &nr_anon_partially_mapped_attr.attr, 650 NULL, 651 }; 652 653 static struct attribute_group anon_stats_attr_grp = { 654 .name = "stats", 655 .attrs = anon_stats_attrs, 656 }; 657 658 static struct attribute *file_stats_attrs[] = { 659 #ifdef CONFIG_SHMEM 660 &shmem_alloc_attr.attr, 661 &shmem_fallback_attr.attr, 662 &shmem_fallback_charge_attr.attr, 663 #endif 664 NULL, 665 }; 666 667 static struct attribute_group file_stats_attr_grp = { 668 .name = "stats", 669 .attrs = file_stats_attrs, 670 }; 671 672 static struct attribute *any_stats_attrs[] = { 673 #ifdef CONFIG_SHMEM 674 &zswpout_attr.attr, 675 &swpin_attr.attr, 676 &swpin_fallback_attr.attr, 677 &swpin_fallback_charge_attr.attr, 678 &swpout_attr.attr, 679 &swpout_fallback_attr.attr, 680 #endif 681 &split_attr.attr, 682 &split_failed_attr.attr, 683 NULL, 684 }; 685 686 static struct attribute_group any_stats_attr_grp = { 687 .name = "stats", 688 .attrs = any_stats_attrs, 689 }; 690 691 static int sysfs_add_group(struct kobject *kobj, 692 const struct attribute_group *grp) 693 { 694 int ret = -ENOENT; 695 696 /* 697 * If the group is named, try to merge first, assuming the subdirectory 698 * was already created. This avoids the warning emitted by 699 * sysfs_create_group() if the directory already exists. 700 */ 701 if (grp->name) 702 ret = sysfs_merge_group(kobj, grp); 703 if (ret) 704 ret = sysfs_create_group(kobj, grp); 705 706 return ret; 707 } 708 709 static struct thpsize *thpsize_create(int order, struct kobject *parent) 710 { 711 unsigned long size = (PAGE_SIZE << order) / SZ_1K; 712 struct thpsize *thpsize; 713 int ret = -ENOMEM; 714 715 thpsize = kzalloc(sizeof(*thpsize), GFP_KERNEL); 716 if (!thpsize) 717 goto err; 718 719 thpsize->order = order; 720 721 ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent, 722 "hugepages-%lukB", size); 723 if (ret) { 724 kfree(thpsize); 725 goto err; 726 } 727 728 729 ret = sysfs_add_group(&thpsize->kobj, &any_ctrl_attr_grp); 730 if (ret) 731 goto err_put; 732 733 ret = sysfs_add_group(&thpsize->kobj, &any_stats_attr_grp); 734 if (ret) 735 goto err_put; 736 737 if (BIT(order) & THP_ORDERS_ALL_ANON) { 738 ret = sysfs_add_group(&thpsize->kobj, &anon_ctrl_attr_grp); 739 if (ret) 740 goto err_put; 741 742 ret = sysfs_add_group(&thpsize->kobj, &anon_stats_attr_grp); 743 if (ret) 744 goto err_put; 745 } 746 747 if (BIT(order) & THP_ORDERS_ALL_FILE_DEFAULT) { 748 ret = sysfs_add_group(&thpsize->kobj, &file_ctrl_attr_grp); 749 if (ret) 750 goto err_put; 751 752 ret = sysfs_add_group(&thpsize->kobj, &file_stats_attr_grp); 753 if (ret) 754 goto err_put; 755 } 756 757 return thpsize; 758 err_put: 759 kobject_put(&thpsize->kobj); 760 err: 761 return ERR_PTR(ret); 762 } 763 764 static void thpsize_release(struct kobject *kobj) 765 { 766 kfree(to_thpsize(kobj)); 767 } 768 769 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 770 { 771 int err; 772 struct thpsize *thpsize; 773 unsigned long orders; 774 int order; 775 776 /* 777 * Default to setting PMD-sized THP to inherit the global setting and 778 * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time 779 * constant so we have to do this here. 780 */ 781 if (!anon_orders_configured) 782 huge_anon_orders_inherit = BIT(PMD_ORDER); 783 784 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 785 if (unlikely(!*hugepage_kobj)) { 786 pr_err("failed to create transparent hugepage kobject\n"); 787 return -ENOMEM; 788 } 789 790 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 791 if (err) { 792 pr_err("failed to register transparent hugepage group\n"); 793 goto delete_obj; 794 } 795 796 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 797 if (err) { 798 pr_err("failed to register transparent hugepage group\n"); 799 goto remove_hp_group; 800 } 801 802 orders = THP_ORDERS_ALL_ANON | THP_ORDERS_ALL_FILE_DEFAULT; 803 order = highest_order(orders); 804 while (orders) { 805 thpsize = thpsize_create(order, *hugepage_kobj); 806 if (IS_ERR(thpsize)) { 807 pr_err("failed to create thpsize for order %d\n", order); 808 err = PTR_ERR(thpsize); 809 goto remove_all; 810 } 811 list_add(&thpsize->node, &thpsize_list); 812 order = next_order(&orders, order); 813 } 814 815 return 0; 816 817 remove_all: 818 hugepage_exit_sysfs(*hugepage_kobj); 819 return err; 820 remove_hp_group: 821 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 822 delete_obj: 823 kobject_put(*hugepage_kobj); 824 return err; 825 } 826 827 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 828 { 829 struct thpsize *thpsize, *tmp; 830 831 list_for_each_entry_safe(thpsize, tmp, &thpsize_list, node) { 832 list_del(&thpsize->node); 833 kobject_put(&thpsize->kobj); 834 } 835 836 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 837 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 838 kobject_put(hugepage_kobj); 839 } 840 #else 841 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 842 { 843 return 0; 844 } 845 846 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 847 { 848 } 849 #endif /* CONFIG_SYSFS */ 850 851 static int __init thp_shrinker_init(void) 852 { 853 huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero"); 854 if (!huge_zero_page_shrinker) 855 return -ENOMEM; 856 857 deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE | 858 SHRINKER_MEMCG_AWARE | 859 SHRINKER_NONSLAB, 860 "thp-deferred_split"); 861 if (!deferred_split_shrinker) { 862 shrinker_free(huge_zero_page_shrinker); 863 return -ENOMEM; 864 } 865 866 huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count; 867 huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan; 868 shrinker_register(huge_zero_page_shrinker); 869 870 deferred_split_shrinker->count_objects = deferred_split_count; 871 deferred_split_shrinker->scan_objects = deferred_split_scan; 872 shrinker_register(deferred_split_shrinker); 873 874 return 0; 875 } 876 877 static void __init thp_shrinker_exit(void) 878 { 879 shrinker_free(huge_zero_page_shrinker); 880 shrinker_free(deferred_split_shrinker); 881 } 882 883 static int __init hugepage_init(void) 884 { 885 int err; 886 struct kobject *hugepage_kobj; 887 888 if (!has_transparent_hugepage()) { 889 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED; 890 return -EINVAL; 891 } 892 893 /* 894 * hugepages can't be allocated by the buddy allocator 895 */ 896 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER > MAX_PAGE_ORDER); 897 898 err = hugepage_init_sysfs(&hugepage_kobj); 899 if (err) 900 goto err_sysfs; 901 902 err = khugepaged_init(); 903 if (err) 904 goto err_slab; 905 906 err = thp_shrinker_init(); 907 if (err) 908 goto err_shrinker; 909 910 /* 911 * By default disable transparent hugepages on smaller systems, 912 * where the extra memory used could hurt more than TLB overhead 913 * is likely to save. The admin can still enable it through /sys. 914 */ 915 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 916 transparent_hugepage_flags = 0; 917 return 0; 918 } 919 920 err = start_stop_khugepaged(); 921 if (err) 922 goto err_khugepaged; 923 924 return 0; 925 err_khugepaged: 926 thp_shrinker_exit(); 927 err_shrinker: 928 khugepaged_destroy(); 929 err_slab: 930 hugepage_exit_sysfs(hugepage_kobj); 931 err_sysfs: 932 return err; 933 } 934 subsys_initcall(hugepage_init); 935 936 static int __init setup_transparent_hugepage(char *str) 937 { 938 int ret = 0; 939 if (!str) 940 goto out; 941 if (!strcmp(str, "always")) { 942 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 943 &transparent_hugepage_flags); 944 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 945 &transparent_hugepage_flags); 946 ret = 1; 947 } else if (!strcmp(str, "madvise")) { 948 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 949 &transparent_hugepage_flags); 950 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 951 &transparent_hugepage_flags); 952 ret = 1; 953 } else if (!strcmp(str, "never")) { 954 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 955 &transparent_hugepage_flags); 956 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 957 &transparent_hugepage_flags); 958 ret = 1; 959 } 960 out: 961 if (!ret) 962 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 963 return ret; 964 } 965 __setup("transparent_hugepage=", setup_transparent_hugepage); 966 967 static char str_dup[PAGE_SIZE] __initdata; 968 static int __init setup_thp_anon(char *str) 969 { 970 char *token, *range, *policy, *subtoken; 971 unsigned long always, inherit, madvise; 972 char *start_size, *end_size; 973 int start, end, nr; 974 char *p; 975 976 if (!str || strlen(str) + 1 > PAGE_SIZE) 977 goto err; 978 strscpy(str_dup, str); 979 980 always = huge_anon_orders_always; 981 madvise = huge_anon_orders_madvise; 982 inherit = huge_anon_orders_inherit; 983 p = str_dup; 984 while ((token = strsep(&p, ";")) != NULL) { 985 range = strsep(&token, ":"); 986 policy = token; 987 988 if (!policy) 989 goto err; 990 991 while ((subtoken = strsep(&range, ",")) != NULL) { 992 if (strchr(subtoken, '-')) { 993 start_size = strsep(&subtoken, "-"); 994 end_size = subtoken; 995 996 start = get_order_from_str(start_size, THP_ORDERS_ALL_ANON); 997 end = get_order_from_str(end_size, THP_ORDERS_ALL_ANON); 998 } else { 999 start_size = end_size = subtoken; 1000 start = end = get_order_from_str(subtoken, 1001 THP_ORDERS_ALL_ANON); 1002 } 1003 1004 if (start == -EINVAL) { 1005 pr_err("invalid size %s in thp_anon boot parameter\n", start_size); 1006 goto err; 1007 } 1008 1009 if (end == -EINVAL) { 1010 pr_err("invalid size %s in thp_anon boot parameter\n", end_size); 1011 goto err; 1012 } 1013 1014 if (start < 0 || end < 0 || start > end) 1015 goto err; 1016 1017 nr = end - start + 1; 1018 if (!strcmp(policy, "always")) { 1019 bitmap_set(&always, start, nr); 1020 bitmap_clear(&inherit, start, nr); 1021 bitmap_clear(&madvise, start, nr); 1022 } else if (!strcmp(policy, "madvise")) { 1023 bitmap_set(&madvise, start, nr); 1024 bitmap_clear(&inherit, start, nr); 1025 bitmap_clear(&always, start, nr); 1026 } else if (!strcmp(policy, "inherit")) { 1027 bitmap_set(&inherit, start, nr); 1028 bitmap_clear(&madvise, start, nr); 1029 bitmap_clear(&always, start, nr); 1030 } else if (!strcmp(policy, "never")) { 1031 bitmap_clear(&inherit, start, nr); 1032 bitmap_clear(&madvise, start, nr); 1033 bitmap_clear(&always, start, nr); 1034 } else { 1035 pr_err("invalid policy %s in thp_anon boot parameter\n", policy); 1036 goto err; 1037 } 1038 } 1039 } 1040 1041 huge_anon_orders_always = always; 1042 huge_anon_orders_madvise = madvise; 1043 huge_anon_orders_inherit = inherit; 1044 anon_orders_configured = true; 1045 return 1; 1046 1047 err: 1048 pr_warn("thp_anon=%s: error parsing string, ignoring setting\n", str); 1049 return 0; 1050 } 1051 __setup("thp_anon=", setup_thp_anon); 1052 1053 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 1054 { 1055 if (likely(vma->vm_flags & VM_WRITE)) 1056 pmd = pmd_mkwrite(pmd, vma); 1057 return pmd; 1058 } 1059 1060 #ifdef CONFIG_MEMCG 1061 static inline 1062 struct deferred_split *get_deferred_split_queue(struct folio *folio) 1063 { 1064 struct mem_cgroup *memcg = folio_memcg(folio); 1065 struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); 1066 1067 if (memcg) 1068 return &memcg->deferred_split_queue; 1069 else 1070 return &pgdat->deferred_split_queue; 1071 } 1072 #else 1073 static inline 1074 struct deferred_split *get_deferred_split_queue(struct folio *folio) 1075 { 1076 struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); 1077 1078 return &pgdat->deferred_split_queue; 1079 } 1080 #endif 1081 1082 static inline bool is_transparent_hugepage(const struct folio *folio) 1083 { 1084 if (!folio_test_large(folio)) 1085 return false; 1086 1087 return is_huge_zero_folio(folio) || 1088 folio_test_large_rmappable(folio); 1089 } 1090 1091 static unsigned long __thp_get_unmapped_area(struct file *filp, 1092 unsigned long addr, unsigned long len, 1093 loff_t off, unsigned long flags, unsigned long size, 1094 vm_flags_t vm_flags) 1095 { 1096 loff_t off_end = off + len; 1097 loff_t off_align = round_up(off, size); 1098 unsigned long len_pad, ret, off_sub; 1099 1100 if (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()) 1101 return 0; 1102 1103 if (off_end <= off_align || (off_end - off_align) < size) 1104 return 0; 1105 1106 len_pad = len + size; 1107 if (len_pad < len || (off + len_pad) < off) 1108 return 0; 1109 1110 ret = mm_get_unmapped_area_vmflags(current->mm, filp, addr, len_pad, 1111 off >> PAGE_SHIFT, flags, vm_flags); 1112 1113 /* 1114 * The failure might be due to length padding. The caller will retry 1115 * without the padding. 1116 */ 1117 if (IS_ERR_VALUE(ret)) 1118 return 0; 1119 1120 /* 1121 * Do not try to align to THP boundary if allocation at the address 1122 * hint succeeds. 1123 */ 1124 if (ret == addr) 1125 return addr; 1126 1127 off_sub = (off - ret) & (size - 1); 1128 1129 if (test_bit(MMF_TOPDOWN, ¤t->mm->flags) && !off_sub) 1130 return ret + size; 1131 1132 ret += off_sub; 1133 return ret; 1134 } 1135 1136 unsigned long thp_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, 1137 unsigned long len, unsigned long pgoff, unsigned long flags, 1138 vm_flags_t vm_flags) 1139 { 1140 unsigned long ret; 1141 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 1142 1143 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE, vm_flags); 1144 if (ret) 1145 return ret; 1146 1147 return mm_get_unmapped_area_vmflags(current->mm, filp, addr, len, pgoff, flags, 1148 vm_flags); 1149 } 1150 1151 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 1152 unsigned long len, unsigned long pgoff, unsigned long flags) 1153 { 1154 return thp_get_unmapped_area_vmflags(filp, addr, len, pgoff, flags, 0); 1155 } 1156 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 1157 1158 static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma, 1159 unsigned long addr) 1160 { 1161 gfp_t gfp = vma_thp_gfp_mask(vma); 1162 const int order = HPAGE_PMD_ORDER; 1163 struct folio *folio; 1164 1165 folio = vma_alloc_folio(gfp, order, vma, addr & HPAGE_PMD_MASK); 1166 1167 if (unlikely(!folio)) { 1168 count_vm_event(THP_FAULT_FALLBACK); 1169 count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK); 1170 return NULL; 1171 } 1172 1173 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 1174 if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) { 1175 folio_put(folio); 1176 count_vm_event(THP_FAULT_FALLBACK); 1177 count_vm_event(THP_FAULT_FALLBACK_CHARGE); 1178 count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK); 1179 count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); 1180 return NULL; 1181 } 1182 folio_throttle_swaprate(folio, gfp); 1183 1184 /* 1185 * When a folio is not zeroed during allocation (__GFP_ZERO not used) 1186 * or user folios require special handling, folio_zero_user() is used to 1187 * make sure that the page corresponding to the faulting address will be 1188 * hot in the cache after zeroing. 1189 */ 1190 if (user_alloc_needs_zeroing()) 1191 folio_zero_user(folio, addr); 1192 /* 1193 * The memory barrier inside __folio_mark_uptodate makes sure that 1194 * folio_zero_user writes become visible before the set_pmd_at() 1195 * write. 1196 */ 1197 __folio_mark_uptodate(folio); 1198 return folio; 1199 } 1200 1201 static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd, 1202 struct vm_area_struct *vma, unsigned long haddr) 1203 { 1204 pmd_t entry; 1205 1206 entry = mk_huge_pmd(&folio->page, vma->vm_page_prot); 1207 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1208 folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE); 1209 folio_add_lru_vma(folio, vma); 1210 set_pmd_at(vma->vm_mm, haddr, pmd, entry); 1211 update_mmu_cache_pmd(vma, haddr, pmd); 1212 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1213 count_vm_event(THP_FAULT_ALLOC); 1214 count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC); 1215 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); 1216 } 1217 1218 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf) 1219 { 1220 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1221 struct vm_area_struct *vma = vmf->vma; 1222 struct folio *folio; 1223 pgtable_t pgtable; 1224 vm_fault_t ret = 0; 1225 1226 folio = vma_alloc_anon_folio_pmd(vma, vmf->address); 1227 if (unlikely(!folio)) 1228 return VM_FAULT_FALLBACK; 1229 1230 pgtable = pte_alloc_one(vma->vm_mm); 1231 if (unlikely(!pgtable)) { 1232 ret = VM_FAULT_OOM; 1233 goto release; 1234 } 1235 1236 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1237 if (unlikely(!pmd_none(*vmf->pmd))) { 1238 goto unlock_release; 1239 } else { 1240 ret = check_stable_address_space(vma->vm_mm); 1241 if (ret) 1242 goto unlock_release; 1243 1244 /* Deliver the page fault to userland */ 1245 if (userfaultfd_missing(vma)) { 1246 spin_unlock(vmf->ptl); 1247 folio_put(folio); 1248 pte_free(vma->vm_mm, pgtable); 1249 ret = handle_userfault(vmf, VM_UFFD_MISSING); 1250 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 1251 return ret; 1252 } 1253 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 1254 map_anon_folio_pmd(folio, vmf->pmd, vma, haddr); 1255 mm_inc_nr_ptes(vma->vm_mm); 1256 deferred_split_folio(folio, false); 1257 spin_unlock(vmf->ptl); 1258 } 1259 1260 return 0; 1261 unlock_release: 1262 spin_unlock(vmf->ptl); 1263 release: 1264 if (pgtable) 1265 pte_free(vma->vm_mm, pgtable); 1266 folio_put(folio); 1267 return ret; 1268 1269 } 1270 1271 /* 1272 * always: directly stall for all thp allocations 1273 * defer: wake kswapd and fail if not immediately available 1274 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 1275 * fail if not immediately available 1276 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 1277 * available 1278 * never: never stall for any thp allocation 1279 */ 1280 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) 1281 { 1282 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); 1283 1284 /* Always do synchronous compaction */ 1285 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 1286 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 1287 1288 /* Kick kcompactd and fail quickly */ 1289 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 1290 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; 1291 1292 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 1293 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 1294 return GFP_TRANSHUGE_LIGHT | 1295 (vma_madvised ? __GFP_DIRECT_RECLAIM : 1296 __GFP_KSWAPD_RECLAIM); 1297 1298 /* Only do synchronous compaction if madvised */ 1299 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 1300 return GFP_TRANSHUGE_LIGHT | 1301 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 1302 1303 return GFP_TRANSHUGE_LIGHT; 1304 } 1305 1306 /* Caller must hold page table lock. */ 1307 static void set_huge_zero_folio(pgtable_t pgtable, struct mm_struct *mm, 1308 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 1309 struct folio *zero_folio) 1310 { 1311 pmd_t entry; 1312 if (!pmd_none(*pmd)) 1313 return; 1314 entry = mk_pmd(&zero_folio->page, vma->vm_page_prot); 1315 entry = pmd_mkhuge(entry); 1316 pgtable_trans_huge_deposit(mm, pmd, pgtable); 1317 set_pmd_at(mm, haddr, pmd, entry); 1318 mm_inc_nr_ptes(mm); 1319 } 1320 1321 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 1322 { 1323 struct vm_area_struct *vma = vmf->vma; 1324 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1325 vm_fault_t ret; 1326 1327 if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER)) 1328 return VM_FAULT_FALLBACK; 1329 ret = vmf_anon_prepare(vmf); 1330 if (ret) 1331 return ret; 1332 khugepaged_enter_vma(vma, vma->vm_flags); 1333 1334 if (!(vmf->flags & FAULT_FLAG_WRITE) && 1335 !mm_forbids_zeropage(vma->vm_mm) && 1336 transparent_hugepage_use_zero_page()) { 1337 pgtable_t pgtable; 1338 struct folio *zero_folio; 1339 vm_fault_t ret; 1340 1341 pgtable = pte_alloc_one(vma->vm_mm); 1342 if (unlikely(!pgtable)) 1343 return VM_FAULT_OOM; 1344 zero_folio = mm_get_huge_zero_folio(vma->vm_mm); 1345 if (unlikely(!zero_folio)) { 1346 pte_free(vma->vm_mm, pgtable); 1347 count_vm_event(THP_FAULT_FALLBACK); 1348 return VM_FAULT_FALLBACK; 1349 } 1350 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1351 ret = 0; 1352 if (pmd_none(*vmf->pmd)) { 1353 ret = check_stable_address_space(vma->vm_mm); 1354 if (ret) { 1355 spin_unlock(vmf->ptl); 1356 pte_free(vma->vm_mm, pgtable); 1357 } else if (userfaultfd_missing(vma)) { 1358 spin_unlock(vmf->ptl); 1359 pte_free(vma->vm_mm, pgtable); 1360 ret = handle_userfault(vmf, VM_UFFD_MISSING); 1361 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 1362 } else { 1363 set_huge_zero_folio(pgtable, vma->vm_mm, vma, 1364 haddr, vmf->pmd, zero_folio); 1365 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1366 spin_unlock(vmf->ptl); 1367 } 1368 } else { 1369 spin_unlock(vmf->ptl); 1370 pte_free(vma->vm_mm, pgtable); 1371 } 1372 return ret; 1373 } 1374 1375 return __do_huge_pmd_anonymous_page(vmf); 1376 } 1377 1378 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 1379 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 1380 pgtable_t pgtable) 1381 { 1382 struct mm_struct *mm = vma->vm_mm; 1383 pmd_t entry; 1384 spinlock_t *ptl; 1385 1386 ptl = pmd_lock(mm, pmd); 1387 if (!pmd_none(*pmd)) { 1388 if (write) { 1389 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 1390 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 1391 goto out_unlock; 1392 } 1393 entry = pmd_mkyoung(*pmd); 1394 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1395 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 1396 update_mmu_cache_pmd(vma, addr, pmd); 1397 } 1398 1399 goto out_unlock; 1400 } 1401 1402 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 1403 if (pfn_t_devmap(pfn)) 1404 entry = pmd_mkdevmap(entry); 1405 else 1406 entry = pmd_mkspecial(entry); 1407 if (write) { 1408 entry = pmd_mkyoung(pmd_mkdirty(entry)); 1409 entry = maybe_pmd_mkwrite(entry, vma); 1410 } 1411 1412 if (pgtable) { 1413 pgtable_trans_huge_deposit(mm, pmd, pgtable); 1414 mm_inc_nr_ptes(mm); 1415 pgtable = NULL; 1416 } 1417 1418 set_pmd_at(mm, addr, pmd, entry); 1419 update_mmu_cache_pmd(vma, addr, pmd); 1420 1421 out_unlock: 1422 spin_unlock(ptl); 1423 if (pgtable) 1424 pte_free(mm, pgtable); 1425 } 1426 1427 /** 1428 * vmf_insert_pfn_pmd - insert a pmd size pfn 1429 * @vmf: Structure describing the fault 1430 * @pfn: pfn to insert 1431 * @write: whether it's a write fault 1432 * 1433 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info. 1434 * 1435 * Return: vm_fault_t value. 1436 */ 1437 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) 1438 { 1439 unsigned long addr = vmf->address & PMD_MASK; 1440 struct vm_area_struct *vma = vmf->vma; 1441 pgprot_t pgprot = vma->vm_page_prot; 1442 pgtable_t pgtable = NULL; 1443 1444 /* 1445 * If we had pmd_special, we could avoid all these restrictions, 1446 * but we need to be consistent with PTEs and architectures that 1447 * can't support a 'special' bit. 1448 */ 1449 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 1450 !pfn_t_devmap(pfn)); 1451 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1452 (VM_PFNMAP|VM_MIXEDMAP)); 1453 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1454 1455 if (addr < vma->vm_start || addr >= vma->vm_end) 1456 return VM_FAULT_SIGBUS; 1457 1458 if (arch_needs_pgtable_deposit()) { 1459 pgtable = pte_alloc_one(vma->vm_mm); 1460 if (!pgtable) 1461 return VM_FAULT_OOM; 1462 } 1463 1464 track_pfn_insert(vma, &pgprot, pfn); 1465 1466 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 1467 return VM_FAULT_NOPAGE; 1468 } 1469 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); 1470 1471 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1472 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 1473 { 1474 if (likely(vma->vm_flags & VM_WRITE)) 1475 pud = pud_mkwrite(pud); 1476 return pud; 1477 } 1478 1479 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 1480 pud_t *pud, pfn_t pfn, bool write) 1481 { 1482 struct mm_struct *mm = vma->vm_mm; 1483 pgprot_t prot = vma->vm_page_prot; 1484 pud_t entry; 1485 spinlock_t *ptl; 1486 1487 ptl = pud_lock(mm, pud); 1488 if (!pud_none(*pud)) { 1489 if (write) { 1490 if (WARN_ON_ONCE(pud_pfn(*pud) != pfn_t_to_pfn(pfn))) 1491 goto out_unlock; 1492 entry = pud_mkyoung(*pud); 1493 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 1494 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 1495 update_mmu_cache_pud(vma, addr, pud); 1496 } 1497 goto out_unlock; 1498 } 1499 1500 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 1501 if (pfn_t_devmap(pfn)) 1502 entry = pud_mkdevmap(entry); 1503 else 1504 entry = pud_mkspecial(entry); 1505 if (write) { 1506 entry = pud_mkyoung(pud_mkdirty(entry)); 1507 entry = maybe_pud_mkwrite(entry, vma); 1508 } 1509 set_pud_at(mm, addr, pud, entry); 1510 update_mmu_cache_pud(vma, addr, pud); 1511 1512 out_unlock: 1513 spin_unlock(ptl); 1514 } 1515 1516 /** 1517 * vmf_insert_pfn_pud - insert a pud size pfn 1518 * @vmf: Structure describing the fault 1519 * @pfn: pfn to insert 1520 * @write: whether it's a write fault 1521 * 1522 * Insert a pud size pfn. See vmf_insert_pfn() for additional info. 1523 * 1524 * Return: vm_fault_t value. 1525 */ 1526 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) 1527 { 1528 unsigned long addr = vmf->address & PUD_MASK; 1529 struct vm_area_struct *vma = vmf->vma; 1530 pgprot_t pgprot = vma->vm_page_prot; 1531 1532 /* 1533 * If we had pud_special, we could avoid all these restrictions, 1534 * but we need to be consistent with PTEs and architectures that 1535 * can't support a 'special' bit. 1536 */ 1537 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 1538 !pfn_t_devmap(pfn)); 1539 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1540 (VM_PFNMAP|VM_MIXEDMAP)); 1541 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1542 1543 if (addr < vma->vm_start || addr >= vma->vm_end) 1544 return VM_FAULT_SIGBUS; 1545 1546 track_pfn_insert(vma, &pgprot, pfn); 1547 1548 insert_pfn_pud(vma, addr, vmf->pud, pfn, write); 1549 return VM_FAULT_NOPAGE; 1550 } 1551 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); 1552 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1553 1554 void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 1555 pmd_t *pmd, bool write) 1556 { 1557 pmd_t _pmd; 1558 1559 _pmd = pmd_mkyoung(*pmd); 1560 if (write) 1561 _pmd = pmd_mkdirty(_pmd); 1562 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 1563 pmd, _pmd, write)) 1564 update_mmu_cache_pmd(vma, addr, pmd); 1565 } 1566 1567 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 1568 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 1569 { 1570 unsigned long pfn = pmd_pfn(*pmd); 1571 struct mm_struct *mm = vma->vm_mm; 1572 struct page *page; 1573 int ret; 1574 1575 assert_spin_locked(pmd_lockptr(mm, pmd)); 1576 1577 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 1578 return NULL; 1579 1580 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 1581 /* pass */; 1582 else 1583 return NULL; 1584 1585 if (flags & FOLL_TOUCH) 1586 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1587 1588 /* 1589 * device mapped pages can only be returned if the 1590 * caller will manage the page reference count. 1591 */ 1592 if (!(flags & (FOLL_GET | FOLL_PIN))) 1593 return ERR_PTR(-EEXIST); 1594 1595 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 1596 *pgmap = get_dev_pagemap(pfn, *pgmap); 1597 if (!*pgmap) 1598 return ERR_PTR(-EFAULT); 1599 page = pfn_to_page(pfn); 1600 ret = try_grab_folio(page_folio(page), 1, flags); 1601 if (ret) 1602 page = ERR_PTR(ret); 1603 1604 return page; 1605 } 1606 1607 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1608 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1609 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) 1610 { 1611 spinlock_t *dst_ptl, *src_ptl; 1612 struct page *src_page; 1613 struct folio *src_folio; 1614 pmd_t pmd; 1615 pgtable_t pgtable = NULL; 1616 int ret = -ENOMEM; 1617 1618 pmd = pmdp_get_lockless(src_pmd); 1619 if (unlikely(pmd_present(pmd) && pmd_special(pmd))) { 1620 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1621 src_ptl = pmd_lockptr(src_mm, src_pmd); 1622 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1623 /* 1624 * No need to recheck the pmd, it can't change with write 1625 * mmap lock held here. 1626 * 1627 * Meanwhile, making sure it's not a CoW VMA with writable 1628 * mapping, otherwise it means either the anon page wrongly 1629 * applied special bit, or we made the PRIVATE mapping be 1630 * able to wrongly write to the backend MMIO. 1631 */ 1632 VM_WARN_ON_ONCE(is_cow_mapping(src_vma->vm_flags) && pmd_write(pmd)); 1633 goto set_pmd; 1634 } 1635 1636 /* Skip if can be re-fill on fault */ 1637 if (!vma_is_anonymous(dst_vma)) 1638 return 0; 1639 1640 pgtable = pte_alloc_one(dst_mm); 1641 if (unlikely(!pgtable)) 1642 goto out; 1643 1644 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1645 src_ptl = pmd_lockptr(src_mm, src_pmd); 1646 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1647 1648 ret = -EAGAIN; 1649 pmd = *src_pmd; 1650 1651 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1652 if (unlikely(is_swap_pmd(pmd))) { 1653 swp_entry_t entry = pmd_to_swp_entry(pmd); 1654 1655 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1656 if (!is_readable_migration_entry(entry)) { 1657 entry = make_readable_migration_entry( 1658 swp_offset(entry)); 1659 pmd = swp_entry_to_pmd(entry); 1660 if (pmd_swp_soft_dirty(*src_pmd)) 1661 pmd = pmd_swp_mksoft_dirty(pmd); 1662 if (pmd_swp_uffd_wp(*src_pmd)) 1663 pmd = pmd_swp_mkuffd_wp(pmd); 1664 set_pmd_at(src_mm, addr, src_pmd, pmd); 1665 } 1666 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1667 mm_inc_nr_ptes(dst_mm); 1668 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1669 if (!userfaultfd_wp(dst_vma)) 1670 pmd = pmd_swp_clear_uffd_wp(pmd); 1671 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1672 ret = 0; 1673 goto out_unlock; 1674 } 1675 #endif 1676 1677 if (unlikely(!pmd_trans_huge(pmd))) { 1678 pte_free(dst_mm, pgtable); 1679 goto out_unlock; 1680 } 1681 /* 1682 * When page table lock is held, the huge zero pmd should not be 1683 * under splitting since we don't split the page itself, only pmd to 1684 * a page table. 1685 */ 1686 if (is_huge_zero_pmd(pmd)) { 1687 /* 1688 * mm_get_huge_zero_folio() will never allocate a new 1689 * folio here, since we already have a zero page to 1690 * copy. It just takes a reference. 1691 */ 1692 mm_get_huge_zero_folio(dst_mm); 1693 goto out_zero_page; 1694 } 1695 1696 src_page = pmd_page(pmd); 1697 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1698 src_folio = page_folio(src_page); 1699 1700 folio_get(src_folio); 1701 if (unlikely(folio_try_dup_anon_rmap_pmd(src_folio, src_page, src_vma))) { 1702 /* Page maybe pinned: split and retry the fault on PTEs. */ 1703 folio_put(src_folio); 1704 pte_free(dst_mm, pgtable); 1705 spin_unlock(src_ptl); 1706 spin_unlock(dst_ptl); 1707 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); 1708 return -EAGAIN; 1709 } 1710 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1711 out_zero_page: 1712 mm_inc_nr_ptes(dst_mm); 1713 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1714 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1715 if (!userfaultfd_wp(dst_vma)) 1716 pmd = pmd_clear_uffd_wp(pmd); 1717 pmd = pmd_wrprotect(pmd); 1718 set_pmd: 1719 pmd = pmd_mkold(pmd); 1720 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1721 1722 ret = 0; 1723 out_unlock: 1724 spin_unlock(src_ptl); 1725 spin_unlock(dst_ptl); 1726 out: 1727 return ret; 1728 } 1729 1730 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1731 void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1732 pud_t *pud, bool write) 1733 { 1734 pud_t _pud; 1735 1736 _pud = pud_mkyoung(*pud); 1737 if (write) 1738 _pud = pud_mkdirty(_pud); 1739 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1740 pud, _pud, write)) 1741 update_mmu_cache_pud(vma, addr, pud); 1742 } 1743 1744 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1745 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1746 struct vm_area_struct *vma) 1747 { 1748 spinlock_t *dst_ptl, *src_ptl; 1749 pud_t pud; 1750 int ret; 1751 1752 dst_ptl = pud_lock(dst_mm, dst_pud); 1753 src_ptl = pud_lockptr(src_mm, src_pud); 1754 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1755 1756 ret = -EAGAIN; 1757 pud = *src_pud; 1758 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1759 goto out_unlock; 1760 1761 /* 1762 * TODO: once we support anonymous pages, use 1763 * folio_try_dup_anon_rmap_*() and split if duplicating fails. 1764 */ 1765 if (is_cow_mapping(vma->vm_flags) && pud_write(pud)) { 1766 pudp_set_wrprotect(src_mm, addr, src_pud); 1767 pud = pud_wrprotect(pud); 1768 } 1769 pud = pud_mkold(pud); 1770 set_pud_at(dst_mm, addr, dst_pud, pud); 1771 1772 ret = 0; 1773 out_unlock: 1774 spin_unlock(src_ptl); 1775 spin_unlock(dst_ptl); 1776 return ret; 1777 } 1778 1779 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1780 { 1781 bool write = vmf->flags & FAULT_FLAG_WRITE; 1782 1783 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1784 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1785 goto unlock; 1786 1787 touch_pud(vmf->vma, vmf->address, vmf->pud, write); 1788 unlock: 1789 spin_unlock(vmf->ptl); 1790 } 1791 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1792 1793 void huge_pmd_set_accessed(struct vm_fault *vmf) 1794 { 1795 bool write = vmf->flags & FAULT_FLAG_WRITE; 1796 1797 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1798 if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) 1799 goto unlock; 1800 1801 touch_pmd(vmf->vma, vmf->address, vmf->pmd, write); 1802 1803 unlock: 1804 spin_unlock(vmf->ptl); 1805 } 1806 1807 static vm_fault_t do_huge_zero_wp_pmd(struct vm_fault *vmf) 1808 { 1809 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1810 struct vm_area_struct *vma = vmf->vma; 1811 struct mmu_notifier_range range; 1812 struct folio *folio; 1813 vm_fault_t ret = 0; 1814 1815 folio = vma_alloc_anon_folio_pmd(vma, vmf->address); 1816 if (unlikely(!folio)) 1817 return VM_FAULT_FALLBACK; 1818 1819 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, haddr, 1820 haddr + HPAGE_PMD_SIZE); 1821 mmu_notifier_invalidate_range_start(&range); 1822 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1823 if (unlikely(!pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd))) 1824 goto release; 1825 ret = check_stable_address_space(vma->vm_mm); 1826 if (ret) 1827 goto release; 1828 (void)pmdp_huge_clear_flush(vma, haddr, vmf->pmd); 1829 map_anon_folio_pmd(folio, vmf->pmd, vma, haddr); 1830 goto unlock; 1831 release: 1832 folio_put(folio); 1833 unlock: 1834 spin_unlock(vmf->ptl); 1835 mmu_notifier_invalidate_range_end(&range); 1836 return ret; 1837 } 1838 1839 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) 1840 { 1841 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; 1842 struct vm_area_struct *vma = vmf->vma; 1843 struct folio *folio; 1844 struct page *page; 1845 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1846 pmd_t orig_pmd = vmf->orig_pmd; 1847 1848 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1849 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1850 1851 if (is_huge_zero_pmd(orig_pmd)) { 1852 vm_fault_t ret = do_huge_zero_wp_pmd(vmf); 1853 1854 if (!(ret & VM_FAULT_FALLBACK)) 1855 return ret; 1856 1857 /* Fallback to splitting PMD if THP cannot be allocated */ 1858 goto fallback; 1859 } 1860 1861 spin_lock(vmf->ptl); 1862 1863 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1864 spin_unlock(vmf->ptl); 1865 return 0; 1866 } 1867 1868 page = pmd_page(orig_pmd); 1869 folio = page_folio(page); 1870 VM_BUG_ON_PAGE(!PageHead(page), page); 1871 1872 /* Early check when only holding the PT lock. */ 1873 if (PageAnonExclusive(page)) 1874 goto reuse; 1875 1876 if (!folio_trylock(folio)) { 1877 folio_get(folio); 1878 spin_unlock(vmf->ptl); 1879 folio_lock(folio); 1880 spin_lock(vmf->ptl); 1881 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1882 spin_unlock(vmf->ptl); 1883 folio_unlock(folio); 1884 folio_put(folio); 1885 return 0; 1886 } 1887 folio_put(folio); 1888 } 1889 1890 /* Recheck after temporarily dropping the PT lock. */ 1891 if (PageAnonExclusive(page)) { 1892 folio_unlock(folio); 1893 goto reuse; 1894 } 1895 1896 /* 1897 * See do_wp_page(): we can only reuse the folio exclusively if 1898 * there are no additional references. Note that we always drain 1899 * the LRU cache immediately after adding a THP. 1900 */ 1901 if (folio_ref_count(folio) > 1902 1 + folio_test_swapcache(folio) * folio_nr_pages(folio)) 1903 goto unlock_fallback; 1904 if (folio_test_swapcache(folio)) 1905 folio_free_swap(folio); 1906 if (folio_ref_count(folio) == 1) { 1907 pmd_t entry; 1908 1909 folio_move_anon_rmap(folio, vma); 1910 SetPageAnonExclusive(page); 1911 folio_unlock(folio); 1912 reuse: 1913 if (unlikely(unshare)) { 1914 spin_unlock(vmf->ptl); 1915 return 0; 1916 } 1917 entry = pmd_mkyoung(orig_pmd); 1918 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1919 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1920 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1921 spin_unlock(vmf->ptl); 1922 return 0; 1923 } 1924 1925 unlock_fallback: 1926 folio_unlock(folio); 1927 spin_unlock(vmf->ptl); 1928 fallback: 1929 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1930 return VM_FAULT_FALLBACK; 1931 } 1932 1933 static inline bool can_change_pmd_writable(struct vm_area_struct *vma, 1934 unsigned long addr, pmd_t pmd) 1935 { 1936 struct page *page; 1937 1938 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) 1939 return false; 1940 1941 /* Don't touch entries that are not even readable (NUMA hinting). */ 1942 if (pmd_protnone(pmd)) 1943 return false; 1944 1945 /* Do we need write faults for softdirty tracking? */ 1946 if (pmd_needs_soft_dirty_wp(vma, pmd)) 1947 return false; 1948 1949 /* Do we need write faults for uffd-wp tracking? */ 1950 if (userfaultfd_huge_pmd_wp(vma, pmd)) 1951 return false; 1952 1953 if (!(vma->vm_flags & VM_SHARED)) { 1954 /* See can_change_pte_writable(). */ 1955 page = vm_normal_page_pmd(vma, addr, pmd); 1956 return page && PageAnon(page) && PageAnonExclusive(page); 1957 } 1958 1959 /* See can_change_pte_writable(). */ 1960 return pmd_dirty(pmd); 1961 } 1962 1963 /* NUMA hinting page fault entry point for trans huge pmds */ 1964 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) 1965 { 1966 struct vm_area_struct *vma = vmf->vma; 1967 struct folio *folio; 1968 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1969 int nid = NUMA_NO_NODE; 1970 int target_nid, last_cpupid; 1971 pmd_t pmd, old_pmd; 1972 bool writable = false; 1973 int flags = 0; 1974 1975 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1976 old_pmd = pmdp_get(vmf->pmd); 1977 1978 if (unlikely(!pmd_same(old_pmd, vmf->orig_pmd))) { 1979 spin_unlock(vmf->ptl); 1980 return 0; 1981 } 1982 1983 pmd = pmd_modify(old_pmd, vma->vm_page_prot); 1984 1985 /* 1986 * Detect now whether the PMD could be writable; this information 1987 * is only valid while holding the PT lock. 1988 */ 1989 writable = pmd_write(pmd); 1990 if (!writable && vma_wants_manual_pte_write_upgrade(vma) && 1991 can_change_pmd_writable(vma, vmf->address, pmd)) 1992 writable = true; 1993 1994 folio = vm_normal_folio_pmd(vma, haddr, pmd); 1995 if (!folio) 1996 goto out_map; 1997 1998 nid = folio_nid(folio); 1999 2000 target_nid = numa_migrate_check(folio, vmf, haddr, &flags, writable, 2001 &last_cpupid); 2002 if (target_nid == NUMA_NO_NODE) 2003 goto out_map; 2004 if (migrate_misplaced_folio_prepare(folio, vma, target_nid)) { 2005 flags |= TNF_MIGRATE_FAIL; 2006 goto out_map; 2007 } 2008 /* The folio is isolated and isolation code holds a folio reference. */ 2009 spin_unlock(vmf->ptl); 2010 writable = false; 2011 2012 if (!migrate_misplaced_folio(folio, target_nid)) { 2013 flags |= TNF_MIGRATED; 2014 nid = target_nid; 2015 task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags); 2016 return 0; 2017 } 2018 2019 flags |= TNF_MIGRATE_FAIL; 2020 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 2021 if (unlikely(!pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd))) { 2022 spin_unlock(vmf->ptl); 2023 return 0; 2024 } 2025 out_map: 2026 /* Restore the PMD */ 2027 pmd = pmd_modify(pmdp_get(vmf->pmd), vma->vm_page_prot); 2028 pmd = pmd_mkyoung(pmd); 2029 if (writable) 2030 pmd = pmd_mkwrite(pmd, vma); 2031 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 2032 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 2033 spin_unlock(vmf->ptl); 2034 2035 if (nid != NUMA_NO_NODE) 2036 task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags); 2037 return 0; 2038 } 2039 2040 /* 2041 * Return true if we do MADV_FREE successfully on entire pmd page. 2042 * Otherwise, return false. 2043 */ 2044 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 2045 pmd_t *pmd, unsigned long addr, unsigned long next) 2046 { 2047 spinlock_t *ptl; 2048 pmd_t orig_pmd; 2049 struct folio *folio; 2050 struct mm_struct *mm = tlb->mm; 2051 bool ret = false; 2052 2053 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 2054 2055 ptl = pmd_trans_huge_lock(pmd, vma); 2056 if (!ptl) 2057 goto out_unlocked; 2058 2059 orig_pmd = *pmd; 2060 if (is_huge_zero_pmd(orig_pmd)) 2061 goto out; 2062 2063 if (unlikely(!pmd_present(orig_pmd))) { 2064 VM_BUG_ON(thp_migration_supported() && 2065 !is_pmd_migration_entry(orig_pmd)); 2066 goto out; 2067 } 2068 2069 folio = pmd_folio(orig_pmd); 2070 /* 2071 * If other processes are mapping this folio, we couldn't discard 2072 * the folio unless they all do MADV_FREE so let's skip the folio. 2073 */ 2074 if (folio_likely_mapped_shared(folio)) 2075 goto out; 2076 2077 if (!folio_trylock(folio)) 2078 goto out; 2079 2080 /* 2081 * If user want to discard part-pages of THP, split it so MADV_FREE 2082 * will deactivate only them. 2083 */ 2084 if (next - addr != HPAGE_PMD_SIZE) { 2085 folio_get(folio); 2086 spin_unlock(ptl); 2087 split_folio(folio); 2088 folio_unlock(folio); 2089 folio_put(folio); 2090 goto out_unlocked; 2091 } 2092 2093 if (folio_test_dirty(folio)) 2094 folio_clear_dirty(folio); 2095 folio_unlock(folio); 2096 2097 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 2098 pmdp_invalidate(vma, addr, pmd); 2099 orig_pmd = pmd_mkold(orig_pmd); 2100 orig_pmd = pmd_mkclean(orig_pmd); 2101 2102 set_pmd_at(mm, addr, pmd, orig_pmd); 2103 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 2104 } 2105 2106 folio_mark_lazyfree(folio); 2107 ret = true; 2108 out: 2109 spin_unlock(ptl); 2110 out_unlocked: 2111 return ret; 2112 } 2113 2114 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 2115 { 2116 pgtable_t pgtable; 2117 2118 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2119 pte_free(mm, pgtable); 2120 mm_dec_nr_ptes(mm); 2121 } 2122 2123 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 2124 pmd_t *pmd, unsigned long addr) 2125 { 2126 pmd_t orig_pmd; 2127 spinlock_t *ptl; 2128 2129 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 2130 2131 ptl = __pmd_trans_huge_lock(pmd, vma); 2132 if (!ptl) 2133 return 0; 2134 /* 2135 * For architectures like ppc64 we look at deposited pgtable 2136 * when calling pmdp_huge_get_and_clear. So do the 2137 * pgtable_trans_huge_withdraw after finishing pmdp related 2138 * operations. 2139 */ 2140 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 2141 tlb->fullmm); 2142 arch_check_zapped_pmd(vma, orig_pmd); 2143 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 2144 if (vma_is_special_huge(vma)) { 2145 if (arch_needs_pgtable_deposit()) 2146 zap_deposited_table(tlb->mm, pmd); 2147 spin_unlock(ptl); 2148 } else if (is_huge_zero_pmd(orig_pmd)) { 2149 zap_deposited_table(tlb->mm, pmd); 2150 spin_unlock(ptl); 2151 } else { 2152 struct folio *folio = NULL; 2153 int flush_needed = 1; 2154 2155 if (pmd_present(orig_pmd)) { 2156 struct page *page = pmd_page(orig_pmd); 2157 2158 folio = page_folio(page); 2159 folio_remove_rmap_pmd(folio, page, vma); 2160 WARN_ON_ONCE(folio_mapcount(folio) < 0); 2161 VM_BUG_ON_PAGE(!PageHead(page), page); 2162 } else if (thp_migration_supported()) { 2163 swp_entry_t entry; 2164 2165 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 2166 entry = pmd_to_swp_entry(orig_pmd); 2167 folio = pfn_swap_entry_folio(entry); 2168 flush_needed = 0; 2169 } else 2170 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 2171 2172 if (folio_test_anon(folio)) { 2173 zap_deposited_table(tlb->mm, pmd); 2174 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 2175 } else { 2176 if (arch_needs_pgtable_deposit()) 2177 zap_deposited_table(tlb->mm, pmd); 2178 add_mm_counter(tlb->mm, mm_counter_file(folio), 2179 -HPAGE_PMD_NR); 2180 } 2181 2182 spin_unlock(ptl); 2183 if (flush_needed) 2184 tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE); 2185 } 2186 return 1; 2187 } 2188 2189 #ifndef pmd_move_must_withdraw 2190 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 2191 spinlock_t *old_pmd_ptl, 2192 struct vm_area_struct *vma) 2193 { 2194 /* 2195 * With split pmd lock we also need to move preallocated 2196 * PTE page table if new_pmd is on different PMD page table. 2197 * 2198 * We also don't deposit and withdraw tables for file pages. 2199 */ 2200 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 2201 } 2202 #endif 2203 2204 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 2205 { 2206 #ifdef CONFIG_MEM_SOFT_DIRTY 2207 if (unlikely(is_pmd_migration_entry(pmd))) 2208 pmd = pmd_swp_mksoft_dirty(pmd); 2209 else if (pmd_present(pmd)) 2210 pmd = pmd_mksoft_dirty(pmd); 2211 #endif 2212 return pmd; 2213 } 2214 2215 static pmd_t clear_uffd_wp_pmd(pmd_t pmd) 2216 { 2217 if (pmd_present(pmd)) 2218 pmd = pmd_clear_uffd_wp(pmd); 2219 else if (is_swap_pmd(pmd)) 2220 pmd = pmd_swp_clear_uffd_wp(pmd); 2221 2222 return pmd; 2223 } 2224 2225 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 2226 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 2227 { 2228 spinlock_t *old_ptl, *new_ptl; 2229 pmd_t pmd; 2230 struct mm_struct *mm = vma->vm_mm; 2231 bool force_flush = false; 2232 2233 /* 2234 * The destination pmd shouldn't be established, free_pgtables() 2235 * should have released it; but move_page_tables() might have already 2236 * inserted a page table, if racing against shmem/file collapse. 2237 */ 2238 if (!pmd_none(*new_pmd)) { 2239 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 2240 return false; 2241 } 2242 2243 /* 2244 * We don't have to worry about the ordering of src and dst 2245 * ptlocks because exclusive mmap_lock prevents deadlock. 2246 */ 2247 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 2248 if (old_ptl) { 2249 new_ptl = pmd_lockptr(mm, new_pmd); 2250 if (new_ptl != old_ptl) 2251 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 2252 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 2253 if (pmd_present(pmd)) 2254 force_flush = true; 2255 VM_BUG_ON(!pmd_none(*new_pmd)); 2256 2257 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 2258 pgtable_t pgtable; 2259 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 2260 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 2261 } 2262 pmd = move_soft_dirty_pmd(pmd); 2263 if (vma_has_uffd_without_event_remap(vma)) 2264 pmd = clear_uffd_wp_pmd(pmd); 2265 set_pmd_at(mm, new_addr, new_pmd, pmd); 2266 if (force_flush) 2267 flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 2268 if (new_ptl != old_ptl) 2269 spin_unlock(new_ptl); 2270 spin_unlock(old_ptl); 2271 return true; 2272 } 2273 return false; 2274 } 2275 2276 /* 2277 * Returns 2278 * - 0 if PMD could not be locked 2279 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary 2280 * or if prot_numa but THP migration is not supported 2281 * - HPAGE_PMD_NR if protections changed and TLB flush necessary 2282 */ 2283 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 2284 pmd_t *pmd, unsigned long addr, pgprot_t newprot, 2285 unsigned long cp_flags) 2286 { 2287 struct mm_struct *mm = vma->vm_mm; 2288 spinlock_t *ptl; 2289 pmd_t oldpmd, entry; 2290 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 2291 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 2292 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 2293 int ret = 1; 2294 2295 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 2296 2297 if (prot_numa && !thp_migration_supported()) 2298 return 1; 2299 2300 ptl = __pmd_trans_huge_lock(pmd, vma); 2301 if (!ptl) 2302 return 0; 2303 2304 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 2305 if (is_swap_pmd(*pmd)) { 2306 swp_entry_t entry = pmd_to_swp_entry(*pmd); 2307 struct folio *folio = pfn_swap_entry_folio(entry); 2308 pmd_t newpmd; 2309 2310 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 2311 if (is_writable_migration_entry(entry)) { 2312 /* 2313 * A protection check is difficult so 2314 * just be safe and disable write 2315 */ 2316 if (folio_test_anon(folio)) 2317 entry = make_readable_exclusive_migration_entry(swp_offset(entry)); 2318 else 2319 entry = make_readable_migration_entry(swp_offset(entry)); 2320 newpmd = swp_entry_to_pmd(entry); 2321 if (pmd_swp_soft_dirty(*pmd)) 2322 newpmd = pmd_swp_mksoft_dirty(newpmd); 2323 } else { 2324 newpmd = *pmd; 2325 } 2326 2327 if (uffd_wp) 2328 newpmd = pmd_swp_mkuffd_wp(newpmd); 2329 else if (uffd_wp_resolve) 2330 newpmd = pmd_swp_clear_uffd_wp(newpmd); 2331 if (!pmd_same(*pmd, newpmd)) 2332 set_pmd_at(mm, addr, pmd, newpmd); 2333 goto unlock; 2334 } 2335 #endif 2336 2337 if (prot_numa) { 2338 struct folio *folio; 2339 bool toptier; 2340 /* 2341 * Avoid trapping faults against the zero page. The read-only 2342 * data is likely to be read-cached on the local CPU and 2343 * local/remote hits to the zero page are not interesting. 2344 */ 2345 if (is_huge_zero_pmd(*pmd)) 2346 goto unlock; 2347 2348 if (pmd_protnone(*pmd)) 2349 goto unlock; 2350 2351 folio = pmd_folio(*pmd); 2352 toptier = node_is_toptier(folio_nid(folio)); 2353 /* 2354 * Skip scanning top tier node if normal numa 2355 * balancing is disabled 2356 */ 2357 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 2358 toptier) 2359 goto unlock; 2360 2361 if (folio_use_access_time(folio)) 2362 folio_xchg_access_time(folio, 2363 jiffies_to_msecs(jiffies)); 2364 } 2365 /* 2366 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 2367 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 2368 * which is also under mmap_read_lock(mm): 2369 * 2370 * CPU0: CPU1: 2371 * change_huge_pmd(prot_numa=1) 2372 * pmdp_huge_get_and_clear_notify() 2373 * madvise_dontneed() 2374 * zap_pmd_range() 2375 * pmd_trans_huge(*pmd) == 0 (without ptl) 2376 * // skip the pmd 2377 * set_pmd_at(); 2378 * // pmd is re-established 2379 * 2380 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 2381 * which may break userspace. 2382 * 2383 * pmdp_invalidate_ad() is required to make sure we don't miss 2384 * dirty/young flags set by hardware. 2385 */ 2386 oldpmd = pmdp_invalidate_ad(vma, addr, pmd); 2387 2388 entry = pmd_modify(oldpmd, newprot); 2389 if (uffd_wp) 2390 entry = pmd_mkuffd_wp(entry); 2391 else if (uffd_wp_resolve) 2392 /* 2393 * Leave the write bit to be handled by PF interrupt 2394 * handler, then things like COW could be properly 2395 * handled. 2396 */ 2397 entry = pmd_clear_uffd_wp(entry); 2398 2399 /* See change_pte_range(). */ 2400 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) && 2401 can_change_pmd_writable(vma, addr, entry)) 2402 entry = pmd_mkwrite(entry, vma); 2403 2404 ret = HPAGE_PMD_NR; 2405 set_pmd_at(mm, addr, pmd, entry); 2406 2407 if (huge_pmd_needs_flush(oldpmd, entry)) 2408 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); 2409 unlock: 2410 spin_unlock(ptl); 2411 return ret; 2412 } 2413 2414 /* 2415 * Returns: 2416 * 2417 * - 0: if pud leaf changed from under us 2418 * - 1: if pud can be skipped 2419 * - HPAGE_PUD_NR: if pud was successfully processed 2420 */ 2421 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 2422 int change_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 2423 pud_t *pudp, unsigned long addr, pgprot_t newprot, 2424 unsigned long cp_flags) 2425 { 2426 struct mm_struct *mm = vma->vm_mm; 2427 pud_t oldpud, entry; 2428 spinlock_t *ptl; 2429 2430 tlb_change_page_size(tlb, HPAGE_PUD_SIZE); 2431 2432 /* NUMA balancing doesn't apply to dax */ 2433 if (cp_flags & MM_CP_PROT_NUMA) 2434 return 1; 2435 2436 /* 2437 * Huge entries on userfault-wp only works with anonymous, while we 2438 * don't have anonymous PUDs yet. 2439 */ 2440 if (WARN_ON_ONCE(cp_flags & MM_CP_UFFD_WP_ALL)) 2441 return 1; 2442 2443 ptl = __pud_trans_huge_lock(pudp, vma); 2444 if (!ptl) 2445 return 0; 2446 2447 /* 2448 * Can't clear PUD or it can race with concurrent zapping. See 2449 * change_huge_pmd(). 2450 */ 2451 oldpud = pudp_invalidate(vma, addr, pudp); 2452 entry = pud_modify(oldpud, newprot); 2453 set_pud_at(mm, addr, pudp, entry); 2454 tlb_flush_pud_range(tlb, addr, HPAGE_PUD_SIZE); 2455 2456 spin_unlock(ptl); 2457 return HPAGE_PUD_NR; 2458 } 2459 #endif 2460 2461 #ifdef CONFIG_USERFAULTFD 2462 /* 2463 * The PT lock for src_pmd and dst_vma/src_vma (for reading) are locked by 2464 * the caller, but it must return after releasing the page_table_lock. 2465 * Just move the page from src_pmd to dst_pmd if possible. 2466 * Return zero if succeeded in moving the page, -EAGAIN if it needs to be 2467 * repeated by the caller, or other errors in case of failure. 2468 */ 2469 int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval, 2470 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, 2471 unsigned long dst_addr, unsigned long src_addr) 2472 { 2473 pmd_t _dst_pmd, src_pmdval; 2474 struct page *src_page; 2475 struct folio *src_folio; 2476 struct anon_vma *src_anon_vma; 2477 spinlock_t *src_ptl, *dst_ptl; 2478 pgtable_t src_pgtable; 2479 struct mmu_notifier_range range; 2480 int err = 0; 2481 2482 src_pmdval = *src_pmd; 2483 src_ptl = pmd_lockptr(mm, src_pmd); 2484 2485 lockdep_assert_held(src_ptl); 2486 vma_assert_locked(src_vma); 2487 vma_assert_locked(dst_vma); 2488 2489 /* Sanity checks before the operation */ 2490 if (WARN_ON_ONCE(!pmd_none(dst_pmdval)) || WARN_ON_ONCE(src_addr & ~HPAGE_PMD_MASK) || 2491 WARN_ON_ONCE(dst_addr & ~HPAGE_PMD_MASK)) { 2492 spin_unlock(src_ptl); 2493 return -EINVAL; 2494 } 2495 2496 if (!pmd_trans_huge(src_pmdval)) { 2497 spin_unlock(src_ptl); 2498 if (is_pmd_migration_entry(src_pmdval)) { 2499 pmd_migration_entry_wait(mm, &src_pmdval); 2500 return -EAGAIN; 2501 } 2502 return -ENOENT; 2503 } 2504 2505 src_page = pmd_page(src_pmdval); 2506 2507 if (!is_huge_zero_pmd(src_pmdval)) { 2508 if (unlikely(!PageAnonExclusive(src_page))) { 2509 spin_unlock(src_ptl); 2510 return -EBUSY; 2511 } 2512 2513 src_folio = page_folio(src_page); 2514 folio_get(src_folio); 2515 } else 2516 src_folio = NULL; 2517 2518 spin_unlock(src_ptl); 2519 2520 flush_cache_range(src_vma, src_addr, src_addr + HPAGE_PMD_SIZE); 2521 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, src_addr, 2522 src_addr + HPAGE_PMD_SIZE); 2523 mmu_notifier_invalidate_range_start(&range); 2524 2525 if (src_folio) { 2526 folio_lock(src_folio); 2527 2528 /* 2529 * split_huge_page walks the anon_vma chain without the page 2530 * lock. Serialize against it with the anon_vma lock, the page 2531 * lock is not enough. 2532 */ 2533 src_anon_vma = folio_get_anon_vma(src_folio); 2534 if (!src_anon_vma) { 2535 err = -EAGAIN; 2536 goto unlock_folio; 2537 } 2538 anon_vma_lock_write(src_anon_vma); 2539 } else 2540 src_anon_vma = NULL; 2541 2542 dst_ptl = pmd_lockptr(mm, dst_pmd); 2543 double_pt_lock(src_ptl, dst_ptl); 2544 if (unlikely(!pmd_same(*src_pmd, src_pmdval) || 2545 !pmd_same(*dst_pmd, dst_pmdval))) { 2546 err = -EAGAIN; 2547 goto unlock_ptls; 2548 } 2549 if (src_folio) { 2550 if (folio_maybe_dma_pinned(src_folio) || 2551 !PageAnonExclusive(&src_folio->page)) { 2552 err = -EBUSY; 2553 goto unlock_ptls; 2554 } 2555 2556 if (WARN_ON_ONCE(!folio_test_head(src_folio)) || 2557 WARN_ON_ONCE(!folio_test_anon(src_folio))) { 2558 err = -EBUSY; 2559 goto unlock_ptls; 2560 } 2561 2562 src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); 2563 /* Folio got pinned from under us. Put it back and fail the move. */ 2564 if (folio_maybe_dma_pinned(src_folio)) { 2565 set_pmd_at(mm, src_addr, src_pmd, src_pmdval); 2566 err = -EBUSY; 2567 goto unlock_ptls; 2568 } 2569 2570 folio_move_anon_rmap(src_folio, dst_vma); 2571 src_folio->index = linear_page_index(dst_vma, dst_addr); 2572 2573 _dst_pmd = mk_huge_pmd(&src_folio->page, dst_vma->vm_page_prot); 2574 /* Follow mremap() behavior and treat the entry dirty after the move */ 2575 _dst_pmd = pmd_mkwrite(pmd_mkdirty(_dst_pmd), dst_vma); 2576 } else { 2577 src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); 2578 _dst_pmd = mk_huge_pmd(src_page, dst_vma->vm_page_prot); 2579 } 2580 set_pmd_at(mm, dst_addr, dst_pmd, _dst_pmd); 2581 2582 src_pgtable = pgtable_trans_huge_withdraw(mm, src_pmd); 2583 pgtable_trans_huge_deposit(mm, dst_pmd, src_pgtable); 2584 unlock_ptls: 2585 double_pt_unlock(src_ptl, dst_ptl); 2586 if (src_anon_vma) { 2587 anon_vma_unlock_write(src_anon_vma); 2588 put_anon_vma(src_anon_vma); 2589 } 2590 unlock_folio: 2591 /* unblock rmap walks */ 2592 if (src_folio) 2593 folio_unlock(src_folio); 2594 mmu_notifier_invalidate_range_end(&range); 2595 if (src_folio) 2596 folio_put(src_folio); 2597 return err; 2598 } 2599 #endif /* CONFIG_USERFAULTFD */ 2600 2601 /* 2602 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 2603 * 2604 * Note that if it returns page table lock pointer, this routine returns without 2605 * unlocking page table lock. So callers must unlock it. 2606 */ 2607 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 2608 { 2609 spinlock_t *ptl; 2610 ptl = pmd_lock(vma->vm_mm, pmd); 2611 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 2612 pmd_devmap(*pmd))) 2613 return ptl; 2614 spin_unlock(ptl); 2615 return NULL; 2616 } 2617 2618 /* 2619 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. 2620 * 2621 * Note that if it returns page table lock pointer, this routine returns without 2622 * unlocking page table lock. So callers must unlock it. 2623 */ 2624 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 2625 { 2626 spinlock_t *ptl; 2627 2628 ptl = pud_lock(vma->vm_mm, pud); 2629 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 2630 return ptl; 2631 spin_unlock(ptl); 2632 return NULL; 2633 } 2634 2635 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 2636 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 2637 pud_t *pud, unsigned long addr) 2638 { 2639 spinlock_t *ptl; 2640 pud_t orig_pud; 2641 2642 ptl = __pud_trans_huge_lock(pud, vma); 2643 if (!ptl) 2644 return 0; 2645 2646 orig_pud = pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm); 2647 arch_check_zapped_pud(vma, orig_pud); 2648 tlb_remove_pud_tlb_entry(tlb, pud, addr); 2649 if (vma_is_special_huge(vma)) { 2650 spin_unlock(ptl); 2651 /* No zero page support yet */ 2652 } else { 2653 /* No support for anonymous PUD pages yet */ 2654 BUG(); 2655 } 2656 return 1; 2657 } 2658 2659 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 2660 unsigned long haddr) 2661 { 2662 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 2663 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2664 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 2665 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 2666 2667 count_vm_event(THP_SPLIT_PUD); 2668 2669 pudp_huge_clear_flush(vma, haddr, pud); 2670 } 2671 2672 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 2673 unsigned long address) 2674 { 2675 spinlock_t *ptl; 2676 struct mmu_notifier_range range; 2677 2678 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, 2679 address & HPAGE_PUD_MASK, 2680 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 2681 mmu_notifier_invalidate_range_start(&range); 2682 ptl = pud_lock(vma->vm_mm, pud); 2683 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 2684 goto out; 2685 __split_huge_pud_locked(vma, pud, range.start); 2686 2687 out: 2688 spin_unlock(ptl); 2689 mmu_notifier_invalidate_range_end(&range); 2690 } 2691 #else 2692 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 2693 unsigned long address) 2694 { 2695 } 2696 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 2697 2698 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2699 unsigned long haddr, pmd_t *pmd) 2700 { 2701 struct mm_struct *mm = vma->vm_mm; 2702 pgtable_t pgtable; 2703 pmd_t _pmd, old_pmd; 2704 unsigned long addr; 2705 pte_t *pte; 2706 int i; 2707 2708 /* 2709 * Leave pmd empty until pte is filled note that it is fine to delay 2710 * notification until mmu_notifier_invalidate_range_end() as we are 2711 * replacing a zero pmd write protected page with a zero pte write 2712 * protected page. 2713 * 2714 * See Documentation/mm/mmu_notifier.rst 2715 */ 2716 old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); 2717 2718 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2719 pmd_populate(mm, &_pmd, pgtable); 2720 2721 pte = pte_offset_map(&_pmd, haddr); 2722 VM_BUG_ON(!pte); 2723 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2724 pte_t entry; 2725 2726 entry = pfn_pte(my_zero_pfn(addr), vma->vm_page_prot); 2727 entry = pte_mkspecial(entry); 2728 if (pmd_uffd_wp(old_pmd)) 2729 entry = pte_mkuffd_wp(entry); 2730 VM_BUG_ON(!pte_none(ptep_get(pte))); 2731 set_pte_at(mm, addr, pte, entry); 2732 pte++; 2733 } 2734 pte_unmap(pte - 1); 2735 smp_wmb(); /* make pte visible before pmd */ 2736 pmd_populate(mm, pmd, pgtable); 2737 } 2738 2739 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2740 unsigned long haddr, bool freeze) 2741 { 2742 struct mm_struct *mm = vma->vm_mm; 2743 struct folio *folio; 2744 struct page *page; 2745 pgtable_t pgtable; 2746 pmd_t old_pmd, _pmd; 2747 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 2748 bool anon_exclusive = false, dirty = false; 2749 unsigned long addr; 2750 pte_t *pte; 2751 int i; 2752 2753 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2754 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2755 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2756 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2757 && !pmd_devmap(*pmd)); 2758 2759 count_vm_event(THP_SPLIT_PMD); 2760 2761 if (!vma_is_anonymous(vma)) { 2762 old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); 2763 /* 2764 * We are going to unmap this huge page. So 2765 * just go ahead and zap it 2766 */ 2767 if (arch_needs_pgtable_deposit()) 2768 zap_deposited_table(mm, pmd); 2769 if (vma_is_special_huge(vma)) 2770 return; 2771 if (unlikely(is_pmd_migration_entry(old_pmd))) { 2772 swp_entry_t entry; 2773 2774 entry = pmd_to_swp_entry(old_pmd); 2775 folio = pfn_swap_entry_folio(entry); 2776 } else { 2777 page = pmd_page(old_pmd); 2778 folio = page_folio(page); 2779 if (!folio_test_dirty(folio) && pmd_dirty(old_pmd)) 2780 folio_mark_dirty(folio); 2781 if (!folio_test_referenced(folio) && pmd_young(old_pmd)) 2782 folio_set_referenced(folio); 2783 folio_remove_rmap_pmd(folio, page, vma); 2784 folio_put(folio); 2785 } 2786 add_mm_counter(mm, mm_counter_file(folio), -HPAGE_PMD_NR); 2787 return; 2788 } 2789 2790 if (is_huge_zero_pmd(*pmd)) { 2791 /* 2792 * FIXME: Do we want to invalidate secondary mmu by calling 2793 * mmu_notifier_arch_invalidate_secondary_tlbs() see comments below 2794 * inside __split_huge_pmd() ? 2795 * 2796 * We are going from a zero huge page write protected to zero 2797 * small page also write protected so it does not seems useful 2798 * to invalidate secondary mmu at this time. 2799 */ 2800 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2801 } 2802 2803 pmd_migration = is_pmd_migration_entry(*pmd); 2804 if (unlikely(pmd_migration)) { 2805 swp_entry_t entry; 2806 2807 old_pmd = *pmd; 2808 entry = pmd_to_swp_entry(old_pmd); 2809 page = pfn_swap_entry_to_page(entry); 2810 write = is_writable_migration_entry(entry); 2811 if (PageAnon(page)) 2812 anon_exclusive = is_readable_exclusive_migration_entry(entry); 2813 young = is_migration_entry_young(entry); 2814 dirty = is_migration_entry_dirty(entry); 2815 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2816 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2817 } else { 2818 /* 2819 * Up to this point the pmd is present and huge and userland has 2820 * the whole access to the hugepage during the split (which 2821 * happens in place). If we overwrite the pmd with the not-huge 2822 * version pointing to the pte here (which of course we could if 2823 * all CPUs were bug free), userland could trigger a small page 2824 * size TLB miss on the small sized TLB while the hugepage TLB 2825 * entry is still established in the huge TLB. Some CPU doesn't 2826 * like that. See 2827 * http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2828 * 383 on page 105. Intel should be safe but is also warns that 2829 * it's only safe if the permission and cache attributes of the 2830 * two entries loaded in the two TLB is identical (which should 2831 * be the case here). But it is generally safer to never allow 2832 * small and huge TLB entries for the same virtual address to be 2833 * loaded simultaneously. So instead of doing "pmd_populate(); 2834 * flush_pmd_tlb_range();" we first mark the current pmd 2835 * notpresent (atomically because here the pmd_trans_huge must 2836 * remain set at all times on the pmd until the split is 2837 * complete for this pmd), then we flush the SMP TLB and finally 2838 * we write the non-huge version of the pmd entry with 2839 * pmd_populate. 2840 */ 2841 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2842 page = pmd_page(old_pmd); 2843 folio = page_folio(page); 2844 if (pmd_dirty(old_pmd)) { 2845 dirty = true; 2846 folio_set_dirty(folio); 2847 } 2848 write = pmd_write(old_pmd); 2849 young = pmd_young(old_pmd); 2850 soft_dirty = pmd_soft_dirty(old_pmd); 2851 uffd_wp = pmd_uffd_wp(old_pmd); 2852 2853 VM_WARN_ON_FOLIO(!folio_ref_count(folio), folio); 2854 VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); 2855 2856 /* 2857 * Without "freeze", we'll simply split the PMD, propagating the 2858 * PageAnonExclusive() flag for each PTE by setting it for 2859 * each subpage -- no need to (temporarily) clear. 2860 * 2861 * With "freeze" we want to replace mapped pages by 2862 * migration entries right away. This is only possible if we 2863 * managed to clear PageAnonExclusive() -- see 2864 * set_pmd_migration_entry(). 2865 * 2866 * In case we cannot clear PageAnonExclusive(), split the PMD 2867 * only and let try_to_migrate_one() fail later. 2868 * 2869 * See folio_try_share_anon_rmap_pmd(): invalidate PMD first. 2870 */ 2871 anon_exclusive = PageAnonExclusive(page); 2872 if (freeze && anon_exclusive && 2873 folio_try_share_anon_rmap_pmd(folio, page)) 2874 freeze = false; 2875 if (!freeze) { 2876 rmap_t rmap_flags = RMAP_NONE; 2877 2878 folio_ref_add(folio, HPAGE_PMD_NR - 1); 2879 if (anon_exclusive) 2880 rmap_flags |= RMAP_EXCLUSIVE; 2881 folio_add_anon_rmap_ptes(folio, page, HPAGE_PMD_NR, 2882 vma, haddr, rmap_flags); 2883 } 2884 } 2885 2886 /* 2887 * Withdraw the table only after we mark the pmd entry invalid. 2888 * This's critical for some architectures (Power). 2889 */ 2890 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2891 pmd_populate(mm, &_pmd, pgtable); 2892 2893 pte = pte_offset_map(&_pmd, haddr); 2894 VM_BUG_ON(!pte); 2895 2896 /* 2897 * Note that NUMA hinting access restrictions are not transferred to 2898 * avoid any possibility of altering permissions across VMAs. 2899 */ 2900 if (freeze || pmd_migration) { 2901 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2902 pte_t entry; 2903 swp_entry_t swp_entry; 2904 2905 if (write) 2906 swp_entry = make_writable_migration_entry( 2907 page_to_pfn(page + i)); 2908 else if (anon_exclusive) 2909 swp_entry = make_readable_exclusive_migration_entry( 2910 page_to_pfn(page + i)); 2911 else 2912 swp_entry = make_readable_migration_entry( 2913 page_to_pfn(page + i)); 2914 if (young) 2915 swp_entry = make_migration_entry_young(swp_entry); 2916 if (dirty) 2917 swp_entry = make_migration_entry_dirty(swp_entry); 2918 entry = swp_entry_to_pte(swp_entry); 2919 if (soft_dirty) 2920 entry = pte_swp_mksoft_dirty(entry); 2921 if (uffd_wp) 2922 entry = pte_swp_mkuffd_wp(entry); 2923 2924 VM_WARN_ON(!pte_none(ptep_get(pte + i))); 2925 set_pte_at(mm, addr, pte + i, entry); 2926 } 2927 } else { 2928 pte_t entry; 2929 2930 entry = mk_pte(page, READ_ONCE(vma->vm_page_prot)); 2931 if (write) 2932 entry = pte_mkwrite(entry, vma); 2933 if (!young) 2934 entry = pte_mkold(entry); 2935 /* NOTE: this may set soft-dirty too on some archs */ 2936 if (dirty) 2937 entry = pte_mkdirty(entry); 2938 if (soft_dirty) 2939 entry = pte_mksoft_dirty(entry); 2940 if (uffd_wp) 2941 entry = pte_mkuffd_wp(entry); 2942 2943 for (i = 0; i < HPAGE_PMD_NR; i++) 2944 VM_WARN_ON(!pte_none(ptep_get(pte + i))); 2945 2946 set_ptes(mm, haddr, pte, entry, HPAGE_PMD_NR); 2947 } 2948 pte_unmap(pte); 2949 2950 if (!pmd_migration) 2951 folio_remove_rmap_pmd(folio, page, vma); 2952 if (freeze) 2953 put_page(page); 2954 2955 smp_wmb(); /* make pte visible before pmd */ 2956 pmd_populate(mm, pmd, pgtable); 2957 } 2958 2959 void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long address, 2960 pmd_t *pmd, bool freeze, struct folio *folio) 2961 { 2962 VM_WARN_ON_ONCE(folio && !folio_test_pmd_mappable(folio)); 2963 VM_WARN_ON_ONCE(!IS_ALIGNED(address, HPAGE_PMD_SIZE)); 2964 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); 2965 VM_BUG_ON(freeze && !folio); 2966 2967 /* 2968 * When the caller requests to set up a migration entry, we 2969 * require a folio to check the PMD against. Otherwise, there 2970 * is a risk of replacing the wrong folio. 2971 */ 2972 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || 2973 is_pmd_migration_entry(*pmd)) { 2974 if (folio && folio != pmd_folio(*pmd)) 2975 return; 2976 __split_huge_pmd_locked(vma, pmd, address, freeze); 2977 } 2978 } 2979 2980 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2981 unsigned long address, bool freeze, struct folio *folio) 2982 { 2983 spinlock_t *ptl; 2984 struct mmu_notifier_range range; 2985 2986 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, 2987 address & HPAGE_PMD_MASK, 2988 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2989 mmu_notifier_invalidate_range_start(&range); 2990 ptl = pmd_lock(vma->vm_mm, pmd); 2991 split_huge_pmd_locked(vma, range.start, pmd, freeze, folio); 2992 spin_unlock(ptl); 2993 mmu_notifier_invalidate_range_end(&range); 2994 } 2995 2996 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2997 bool freeze, struct folio *folio) 2998 { 2999 pmd_t *pmd = mm_find_pmd(vma->vm_mm, address); 3000 3001 if (!pmd) 3002 return; 3003 3004 __split_huge_pmd(vma, pmd, address, freeze, folio); 3005 } 3006 3007 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) 3008 { 3009 /* 3010 * If the new address isn't hpage aligned and it could previously 3011 * contain an hugepage: check if we need to split an huge pmd. 3012 */ 3013 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && 3014 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), 3015 ALIGN(address, HPAGE_PMD_SIZE))) 3016 split_huge_pmd_address(vma, address, false, NULL); 3017 } 3018 3019 void vma_adjust_trans_huge(struct vm_area_struct *vma, 3020 unsigned long start, 3021 unsigned long end, 3022 long adjust_next) 3023 { 3024 /* Check if we need to split start first. */ 3025 split_huge_pmd_if_needed(vma, start); 3026 3027 /* Check if we need to split end next. */ 3028 split_huge_pmd_if_needed(vma, end); 3029 3030 /* 3031 * If we're also updating the next vma vm_start, 3032 * check if we need to split it. 3033 */ 3034 if (adjust_next > 0) { 3035 struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end); 3036 unsigned long nstart = next->vm_start; 3037 nstart += adjust_next; 3038 split_huge_pmd_if_needed(next, nstart); 3039 } 3040 } 3041 3042 static void unmap_folio(struct folio *folio) 3043 { 3044 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SYNC | 3045 TTU_BATCH_FLUSH; 3046 3047 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 3048 3049 if (folio_test_pmd_mappable(folio)) 3050 ttu_flags |= TTU_SPLIT_HUGE_PMD; 3051 3052 /* 3053 * Anon pages need migration entries to preserve them, but file 3054 * pages can simply be left unmapped, then faulted back on demand. 3055 * If that is ever changed (perhaps for mlock), update remap_page(). 3056 */ 3057 if (folio_test_anon(folio)) 3058 try_to_migrate(folio, ttu_flags); 3059 else 3060 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); 3061 3062 try_to_unmap_flush(); 3063 } 3064 3065 static bool __discard_anon_folio_pmd_locked(struct vm_area_struct *vma, 3066 unsigned long addr, pmd_t *pmdp, 3067 struct folio *folio) 3068 { 3069 struct mm_struct *mm = vma->vm_mm; 3070 int ref_count, map_count; 3071 pmd_t orig_pmd = *pmdp; 3072 3073 if (folio_test_dirty(folio) || pmd_dirty(orig_pmd)) 3074 return false; 3075 3076 orig_pmd = pmdp_huge_clear_flush(vma, addr, pmdp); 3077 3078 /* 3079 * Syncing against concurrent GUP-fast: 3080 * - clear PMD; barrier; read refcount 3081 * - inc refcount; barrier; read PMD 3082 */ 3083 smp_mb(); 3084 3085 ref_count = folio_ref_count(folio); 3086 map_count = folio_mapcount(folio); 3087 3088 /* 3089 * Order reads for folio refcount and dirty flag 3090 * (see comments in __remove_mapping()). 3091 */ 3092 smp_rmb(); 3093 3094 /* 3095 * If the folio or its PMD is redirtied at this point, or if there 3096 * are unexpected references, we will give up to discard this folio 3097 * and remap it. 3098 * 3099 * The only folio refs must be one from isolation plus the rmap(s). 3100 */ 3101 if (folio_test_dirty(folio) || pmd_dirty(orig_pmd) || 3102 ref_count != map_count + 1) { 3103 set_pmd_at(mm, addr, pmdp, orig_pmd); 3104 return false; 3105 } 3106 3107 folio_remove_rmap_pmd(folio, pmd_page(orig_pmd), vma); 3108 zap_deposited_table(mm, pmdp); 3109 add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR); 3110 if (vma->vm_flags & VM_LOCKED) 3111 mlock_drain_local(); 3112 folio_put(folio); 3113 3114 return true; 3115 } 3116 3117 bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr, 3118 pmd_t *pmdp, struct folio *folio) 3119 { 3120 VM_WARN_ON_FOLIO(!folio_test_pmd_mappable(folio), folio); 3121 VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); 3122 VM_WARN_ON_ONCE(!IS_ALIGNED(addr, HPAGE_PMD_SIZE)); 3123 3124 if (folio_test_anon(folio) && !folio_test_swapbacked(folio)) 3125 return __discard_anon_folio_pmd_locked(vma, addr, pmdp, folio); 3126 3127 return false; 3128 } 3129 3130 static void remap_page(struct folio *folio, unsigned long nr, int flags) 3131 { 3132 int i = 0; 3133 3134 /* If unmap_folio() uses try_to_migrate() on file, remove this check */ 3135 if (!folio_test_anon(folio)) 3136 return; 3137 for (;;) { 3138 remove_migration_ptes(folio, folio, RMP_LOCKED | flags); 3139 i += folio_nr_pages(folio); 3140 if (i >= nr) 3141 break; 3142 folio = folio_next(folio); 3143 } 3144 } 3145 3146 static void lru_add_page_tail(struct folio *folio, struct page *tail, 3147 struct lruvec *lruvec, struct list_head *list) 3148 { 3149 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 3150 VM_BUG_ON_FOLIO(PageLRU(tail), folio); 3151 lockdep_assert_held(&lruvec->lru_lock); 3152 3153 if (list) { 3154 /* page reclaim is reclaiming a huge page */ 3155 VM_WARN_ON(folio_test_lru(folio)); 3156 get_page(tail); 3157 list_add_tail(&tail->lru, list); 3158 } else { 3159 /* head is still on lru (and we have it frozen) */ 3160 VM_WARN_ON(!folio_test_lru(folio)); 3161 if (folio_test_unevictable(folio)) 3162 tail->mlock_count = 0; 3163 else 3164 list_add_tail(&tail->lru, &folio->lru); 3165 SetPageLRU(tail); 3166 } 3167 } 3168 3169 static void __split_huge_page_tail(struct folio *folio, int tail, 3170 struct lruvec *lruvec, struct list_head *list, 3171 unsigned int new_order) 3172 { 3173 struct page *head = &folio->page; 3174 struct page *page_tail = head + tail; 3175 /* 3176 * Careful: new_folio is not a "real" folio before we cleared PageTail. 3177 * Don't pass it around before clear_compound_head(). 3178 */ 3179 struct folio *new_folio = (struct folio *)page_tail; 3180 3181 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 3182 3183 /* 3184 * Clone page flags before unfreezing refcount. 3185 * 3186 * After successful get_page_unless_zero() might follow flags change, 3187 * for example lock_page() which set PG_waiters. 3188 * 3189 * Note that for mapped sub-pages of an anonymous THP, 3190 * PG_anon_exclusive has been cleared in unmap_folio() and is stored in 3191 * the migration entry instead from where remap_page() will restore it. 3192 * We can still have PG_anon_exclusive set on effectively unmapped and 3193 * unreferenced sub-pages of an anonymous THP: we can simply drop 3194 * PG_anon_exclusive (-> PG_mappedtodisk) for these here. 3195 */ 3196 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 3197 page_tail->flags |= (head->flags & 3198 ((1L << PG_referenced) | 3199 (1L << PG_swapbacked) | 3200 (1L << PG_swapcache) | 3201 (1L << PG_mlocked) | 3202 (1L << PG_uptodate) | 3203 (1L << PG_active) | 3204 (1L << PG_workingset) | 3205 (1L << PG_locked) | 3206 (1L << PG_unevictable) | 3207 #ifdef CONFIG_ARCH_USES_PG_ARCH_2 3208 (1L << PG_arch_2) | 3209 #endif 3210 #ifdef CONFIG_ARCH_USES_PG_ARCH_3 3211 (1L << PG_arch_3) | 3212 #endif 3213 (1L << PG_dirty) | 3214 LRU_GEN_MASK | LRU_REFS_MASK)); 3215 3216 /* ->mapping in first and second tail page is replaced by other uses */ 3217 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 3218 page_tail); 3219 new_folio->mapping = folio->mapping; 3220 new_folio->index = folio->index + tail; 3221 3222 /* 3223 * page->private should not be set in tail pages. Fix up and warn once 3224 * if private is unexpectedly set. 3225 */ 3226 if (unlikely(page_tail->private)) { 3227 VM_WARN_ON_ONCE_PAGE(true, page_tail); 3228 page_tail->private = 0; 3229 } 3230 if (folio_test_swapcache(folio)) 3231 new_folio->swap.val = folio->swap.val + tail; 3232 3233 /* Page flags must be visible before we make the page non-compound. */ 3234 smp_wmb(); 3235 3236 /* 3237 * Clear PageTail before unfreezing page refcount. 3238 * 3239 * After successful get_page_unless_zero() might follow put_page() 3240 * which needs correct compound_head(). 3241 */ 3242 clear_compound_head(page_tail); 3243 if (new_order) { 3244 prep_compound_page(page_tail, new_order); 3245 folio_set_large_rmappable(new_folio); 3246 } 3247 3248 /* Finally unfreeze refcount. Additional reference from page cache. */ 3249 page_ref_unfreeze(page_tail, 3250 1 + ((!folio_test_anon(folio) || folio_test_swapcache(folio)) ? 3251 folio_nr_pages(new_folio) : 0)); 3252 3253 if (folio_test_young(folio)) 3254 folio_set_young(new_folio); 3255 if (folio_test_idle(folio)) 3256 folio_set_idle(new_folio); 3257 3258 folio_xchg_last_cpupid(new_folio, folio_last_cpupid(folio)); 3259 3260 /* 3261 * always add to the tail because some iterators expect new 3262 * pages to show after the currently processed elements - e.g. 3263 * migrate_pages 3264 */ 3265 lru_add_page_tail(folio, page_tail, lruvec, list); 3266 } 3267 3268 static void __split_huge_page(struct page *page, struct list_head *list, 3269 pgoff_t end, unsigned int new_order) 3270 { 3271 struct folio *folio = page_folio(page); 3272 struct page *head = &folio->page; 3273 struct lruvec *lruvec; 3274 struct address_space *swap_cache = NULL; 3275 unsigned long offset = 0; 3276 int i, nr_dropped = 0; 3277 unsigned int new_nr = 1 << new_order; 3278 int order = folio_order(folio); 3279 unsigned int nr = 1 << order; 3280 3281 /* complete memcg works before add pages to LRU */ 3282 split_page_memcg(head, order, new_order); 3283 3284 if (folio_test_anon(folio) && folio_test_swapcache(folio)) { 3285 offset = swap_cache_index(folio->swap); 3286 swap_cache = swap_address_space(folio->swap); 3287 xa_lock(&swap_cache->i_pages); 3288 } 3289 3290 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ 3291 lruvec = folio_lruvec_lock(folio); 3292 3293 folio_clear_has_hwpoisoned(folio); 3294 3295 for (i = nr - new_nr; i >= new_nr; i -= new_nr) { 3296 struct folio *tail; 3297 __split_huge_page_tail(folio, i, lruvec, list, new_order); 3298 tail = page_folio(head + i); 3299 /* Some pages can be beyond EOF: drop them from page cache */ 3300 if (tail->index >= end) { 3301 if (shmem_mapping(folio->mapping)) 3302 nr_dropped++; 3303 else if (folio_test_clear_dirty(tail)) 3304 folio_account_cleaned(tail, 3305 inode_to_wb(folio->mapping->host)); 3306 __filemap_remove_folio(tail, NULL); 3307 folio_put(tail); 3308 } else if (!folio_test_anon(folio)) { 3309 __xa_store(&folio->mapping->i_pages, tail->index, 3310 tail, 0); 3311 } else if (swap_cache) { 3312 __xa_store(&swap_cache->i_pages, offset + i, 3313 tail, 0); 3314 } 3315 } 3316 3317 if (!new_order) 3318 ClearPageCompound(head); 3319 else { 3320 struct folio *new_folio = (struct folio *)head; 3321 3322 folio_set_order(new_folio, new_order); 3323 } 3324 unlock_page_lruvec(lruvec); 3325 /* Caller disabled irqs, so they are still disabled here */ 3326 3327 split_page_owner(head, order, new_order); 3328 pgalloc_tag_split(folio, order, new_order); 3329 3330 /* See comment in __split_huge_page_tail() */ 3331 if (folio_test_anon(folio)) { 3332 /* Additional pin to swap cache */ 3333 if (folio_test_swapcache(folio)) { 3334 folio_ref_add(folio, 1 + new_nr); 3335 xa_unlock(&swap_cache->i_pages); 3336 } else { 3337 folio_ref_inc(folio); 3338 } 3339 } else { 3340 /* Additional pin to page cache */ 3341 folio_ref_add(folio, 1 + new_nr); 3342 xa_unlock(&folio->mapping->i_pages); 3343 } 3344 local_irq_enable(); 3345 3346 if (nr_dropped) 3347 shmem_uncharge(folio->mapping->host, nr_dropped); 3348 remap_page(folio, nr, PageAnon(head) ? RMP_USE_SHARED_ZEROPAGE : 0); 3349 3350 /* 3351 * set page to its compound_head when split to non order-0 pages, so 3352 * we can skip unlocking it below, since PG_locked is transferred to 3353 * the compound_head of the page and the caller will unlock it. 3354 */ 3355 if (new_order) 3356 page = compound_head(page); 3357 3358 for (i = 0; i < nr; i += new_nr) { 3359 struct page *subpage = head + i; 3360 struct folio *new_folio = page_folio(subpage); 3361 if (subpage == page) 3362 continue; 3363 folio_unlock(new_folio); 3364 3365 /* 3366 * Subpages may be freed if there wasn't any mapping 3367 * like if add_to_swap() is running on a lru page that 3368 * had its mapping zapped. And freeing these pages 3369 * requires taking the lru_lock so we do the put_page 3370 * of the tail pages after the split is complete. 3371 */ 3372 free_page_and_swap_cache(subpage); 3373 } 3374 } 3375 3376 /* Racy check whether the huge page can be split */ 3377 bool can_split_folio(struct folio *folio, int caller_pins, int *pextra_pins) 3378 { 3379 int extra_pins; 3380 3381 /* Additional pins from page cache */ 3382 if (folio_test_anon(folio)) 3383 extra_pins = folio_test_swapcache(folio) ? 3384 folio_nr_pages(folio) : 0; 3385 else 3386 extra_pins = folio_nr_pages(folio); 3387 if (pextra_pins) 3388 *pextra_pins = extra_pins; 3389 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 3390 caller_pins; 3391 } 3392 3393 /* 3394 * This function splits a large folio into smaller folios of order @new_order. 3395 * @page can point to any page of the large folio to split. The split operation 3396 * does not change the position of @page. 3397 * 3398 * Prerequisites: 3399 * 3400 * 1) The caller must hold a reference on the @page's owning folio, also known 3401 * as the large folio. 3402 * 3403 * 2) The large folio must be locked. 3404 * 3405 * 3) The folio must not be pinned. Any unexpected folio references, including 3406 * GUP pins, will result in the folio not getting split; instead, the caller 3407 * will receive an -EAGAIN. 3408 * 3409 * 4) @new_order > 1, usually. Splitting to order-1 anonymous folios is not 3410 * supported for non-file-backed folios, because folio->_deferred_list, which 3411 * is used by partially mapped folios, is stored in subpage 2, but an order-1 3412 * folio only has subpages 0 and 1. File-backed order-1 folios are supported, 3413 * since they do not use _deferred_list. 3414 * 3415 * After splitting, the caller's folio reference will be transferred to @page, 3416 * resulting in a raised refcount of @page after this call. The other pages may 3417 * be freed if they are not mapped. 3418 * 3419 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 3420 * 3421 * Pages in @new_order will inherit the mapping, flags, and so on from the 3422 * huge page. 3423 * 3424 * Returns 0 if the huge page was split successfully. 3425 * 3426 * Returns -EAGAIN if the folio has unexpected reference (e.g., GUP) or if 3427 * the folio was concurrently removed from the page cache. 3428 * 3429 * Returns -EBUSY when trying to split the huge zeropage, if the folio is 3430 * under writeback, if fs-specific folio metadata cannot currently be 3431 * released, or if some unexpected race happened (e.g., anon VMA disappeared, 3432 * truncation). 3433 * 3434 * Callers should ensure that the order respects the address space mapping 3435 * min-order if one is set for non-anonymous folios. 3436 * 3437 * Returns -EINVAL when trying to split to an order that is incompatible 3438 * with the folio. Splitting to order 0 is compatible with all folios. 3439 */ 3440 int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, 3441 unsigned int new_order) 3442 { 3443 struct folio *folio = page_folio(page); 3444 struct deferred_split *ds_queue = get_deferred_split_queue(folio); 3445 /* reset xarray order to new order after split */ 3446 XA_STATE_ORDER(xas, &folio->mapping->i_pages, folio->index, new_order); 3447 bool is_anon = folio_test_anon(folio); 3448 struct address_space *mapping = NULL; 3449 struct anon_vma *anon_vma = NULL; 3450 int order = folio_order(folio); 3451 int extra_pins, ret; 3452 pgoff_t end; 3453 bool is_hzp; 3454 3455 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); 3456 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 3457 3458 if (new_order >= folio_order(folio)) 3459 return -EINVAL; 3460 3461 if (is_anon) { 3462 /* order-1 is not supported for anonymous THP. */ 3463 if (new_order == 1) { 3464 VM_WARN_ONCE(1, "Cannot split to order-1 folio"); 3465 return -EINVAL; 3466 } 3467 } else if (new_order) { 3468 /* Split shmem folio to non-zero order not supported */ 3469 if (shmem_mapping(folio->mapping)) { 3470 VM_WARN_ONCE(1, 3471 "Cannot split shmem folio to non-0 order"); 3472 return -EINVAL; 3473 } 3474 /* 3475 * No split if the file system does not support large folio. 3476 * Note that we might still have THPs in such mappings due to 3477 * CONFIG_READ_ONLY_THP_FOR_FS. But in that case, the mapping 3478 * does not actually support large folios properly. 3479 */ 3480 if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && 3481 !mapping_large_folio_support(folio->mapping)) { 3482 VM_WARN_ONCE(1, 3483 "Cannot split file folio to non-0 order"); 3484 return -EINVAL; 3485 } 3486 } 3487 3488 /* Only swapping a whole PMD-mapped folio is supported */ 3489 if (folio_test_swapcache(folio) && new_order) 3490 return -EINVAL; 3491 3492 is_hzp = is_huge_zero_folio(folio); 3493 if (is_hzp) { 3494 pr_warn_ratelimited("Called split_huge_page for huge zero page\n"); 3495 return -EBUSY; 3496 } 3497 3498 if (folio_test_writeback(folio)) 3499 return -EBUSY; 3500 3501 if (is_anon) { 3502 /* 3503 * The caller does not necessarily hold an mmap_lock that would 3504 * prevent the anon_vma disappearing so we first we take a 3505 * reference to it and then lock the anon_vma for write. This 3506 * is similar to folio_lock_anon_vma_read except the write lock 3507 * is taken to serialise against parallel split or collapse 3508 * operations. 3509 */ 3510 anon_vma = folio_get_anon_vma(folio); 3511 if (!anon_vma) { 3512 ret = -EBUSY; 3513 goto out; 3514 } 3515 end = -1; 3516 mapping = NULL; 3517 anon_vma_lock_write(anon_vma); 3518 } else { 3519 unsigned int min_order; 3520 gfp_t gfp; 3521 3522 mapping = folio->mapping; 3523 3524 /* Truncated ? */ 3525 if (!mapping) { 3526 ret = -EBUSY; 3527 goto out; 3528 } 3529 3530 min_order = mapping_min_folio_order(folio->mapping); 3531 if (new_order < min_order) { 3532 VM_WARN_ONCE(1, "Cannot split mapped folio below min-order: %u", 3533 min_order); 3534 ret = -EINVAL; 3535 goto out; 3536 } 3537 3538 gfp = current_gfp_context(mapping_gfp_mask(mapping) & 3539 GFP_RECLAIM_MASK); 3540 3541 if (!filemap_release_folio(folio, gfp)) { 3542 ret = -EBUSY; 3543 goto out; 3544 } 3545 3546 xas_split_alloc(&xas, folio, folio_order(folio), gfp); 3547 if (xas_error(&xas)) { 3548 ret = xas_error(&xas); 3549 goto out; 3550 } 3551 3552 anon_vma = NULL; 3553 i_mmap_lock_read(mapping); 3554 3555 /* 3556 *__split_huge_page() may need to trim off pages beyond EOF: 3557 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 3558 * which cannot be nested inside the page tree lock. So note 3559 * end now: i_size itself may be changed at any moment, but 3560 * folio lock is good enough to serialize the trimming. 3561 */ 3562 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 3563 if (shmem_mapping(mapping)) 3564 end = shmem_fallocend(mapping->host, end); 3565 } 3566 3567 /* 3568 * Racy check if we can split the page, before unmap_folio() will 3569 * split PMDs 3570 */ 3571 if (!can_split_folio(folio, 1, &extra_pins)) { 3572 ret = -EAGAIN; 3573 goto out_unlock; 3574 } 3575 3576 unmap_folio(folio); 3577 3578 /* block interrupt reentry in xa_lock and spinlock */ 3579 local_irq_disable(); 3580 if (mapping) { 3581 /* 3582 * Check if the folio is present in page cache. 3583 * We assume all tail are present too, if folio is there. 3584 */ 3585 xas_lock(&xas); 3586 xas_reset(&xas); 3587 if (xas_load(&xas) != folio) 3588 goto fail; 3589 } 3590 3591 /* Prevent deferred_split_scan() touching ->_refcount */ 3592 spin_lock(&ds_queue->split_queue_lock); 3593 if (folio_ref_freeze(folio, 1 + extra_pins)) { 3594 if (folio_order(folio) > 1 && 3595 !list_empty(&folio->_deferred_list)) { 3596 ds_queue->split_queue_len--; 3597 if (folio_test_partially_mapped(folio)) { 3598 folio_clear_partially_mapped(folio); 3599 mod_mthp_stat(folio_order(folio), 3600 MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); 3601 } 3602 /* 3603 * Reinitialize page_deferred_list after removing the 3604 * page from the split_queue, otherwise a subsequent 3605 * split will see list corruption when checking the 3606 * page_deferred_list. 3607 */ 3608 list_del_init(&folio->_deferred_list); 3609 } 3610 spin_unlock(&ds_queue->split_queue_lock); 3611 if (mapping) { 3612 int nr = folio_nr_pages(folio); 3613 3614 xas_split(&xas, folio, folio_order(folio)); 3615 if (folio_test_pmd_mappable(folio) && 3616 new_order < HPAGE_PMD_ORDER) { 3617 if (folio_test_swapbacked(folio)) { 3618 __lruvec_stat_mod_folio(folio, 3619 NR_SHMEM_THPS, -nr); 3620 } else { 3621 __lruvec_stat_mod_folio(folio, 3622 NR_FILE_THPS, -nr); 3623 filemap_nr_thps_dec(mapping); 3624 } 3625 } 3626 } 3627 3628 if (is_anon) { 3629 mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); 3630 mod_mthp_stat(new_order, MTHP_STAT_NR_ANON, 1 << (order - new_order)); 3631 } 3632 __split_huge_page(page, list, end, new_order); 3633 ret = 0; 3634 } else { 3635 spin_unlock(&ds_queue->split_queue_lock); 3636 fail: 3637 if (mapping) 3638 xas_unlock(&xas); 3639 local_irq_enable(); 3640 remap_page(folio, folio_nr_pages(folio), 0); 3641 ret = -EAGAIN; 3642 } 3643 3644 out_unlock: 3645 if (anon_vma) { 3646 anon_vma_unlock_write(anon_vma); 3647 put_anon_vma(anon_vma); 3648 } 3649 if (mapping) 3650 i_mmap_unlock_read(mapping); 3651 out: 3652 xas_destroy(&xas); 3653 if (order == HPAGE_PMD_ORDER) 3654 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 3655 count_mthp_stat(order, !ret ? MTHP_STAT_SPLIT : MTHP_STAT_SPLIT_FAILED); 3656 return ret; 3657 } 3658 3659 int min_order_for_split(struct folio *folio) 3660 { 3661 if (folio_test_anon(folio)) 3662 return 0; 3663 3664 if (!folio->mapping) { 3665 if (folio_test_pmd_mappable(folio)) 3666 count_vm_event(THP_SPLIT_PAGE_FAILED); 3667 return -EBUSY; 3668 } 3669 3670 return mapping_min_folio_order(folio->mapping); 3671 } 3672 3673 int split_folio_to_list(struct folio *folio, struct list_head *list) 3674 { 3675 int ret = min_order_for_split(folio); 3676 3677 if (ret < 0) 3678 return ret; 3679 3680 return split_huge_page_to_list_to_order(&folio->page, list, ret); 3681 } 3682 3683 /* 3684 * __folio_unqueue_deferred_split() is not to be called directly: 3685 * the folio_unqueue_deferred_split() inline wrapper in mm/internal.h 3686 * limits its calls to those folios which may have a _deferred_list for 3687 * queueing THP splits, and that list is (racily observed to be) non-empty. 3688 * 3689 * It is unsafe to call folio_unqueue_deferred_split() until folio refcount is 3690 * zero: because even when split_queue_lock is held, a non-empty _deferred_list 3691 * might be in use on deferred_split_scan()'s unlocked on-stack list. 3692 * 3693 * If memory cgroups are enabled, split_queue_lock is in the mem_cgroup: it is 3694 * therefore important to unqueue deferred split before changing folio memcg. 3695 */ 3696 bool __folio_unqueue_deferred_split(struct folio *folio) 3697 { 3698 struct deferred_split *ds_queue; 3699 unsigned long flags; 3700 bool unqueued = false; 3701 3702 WARN_ON_ONCE(folio_ref_count(folio)); 3703 WARN_ON_ONCE(!mem_cgroup_disabled() && !folio_memcg(folio)); 3704 3705 ds_queue = get_deferred_split_queue(folio); 3706 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3707 if (!list_empty(&folio->_deferred_list)) { 3708 ds_queue->split_queue_len--; 3709 if (folio_test_partially_mapped(folio)) { 3710 folio_clear_partially_mapped(folio); 3711 mod_mthp_stat(folio_order(folio), 3712 MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); 3713 } 3714 list_del_init(&folio->_deferred_list); 3715 unqueued = true; 3716 } 3717 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3718 3719 return unqueued; /* useful for debug warnings */ 3720 } 3721 3722 /* partially_mapped=false won't clear PG_partially_mapped folio flag */ 3723 void deferred_split_folio(struct folio *folio, bool partially_mapped) 3724 { 3725 struct deferred_split *ds_queue = get_deferred_split_queue(folio); 3726 #ifdef CONFIG_MEMCG 3727 struct mem_cgroup *memcg = folio_memcg(folio); 3728 #endif 3729 unsigned long flags; 3730 3731 /* 3732 * Order 1 folios have no space for a deferred list, but we also 3733 * won't waste much memory by not adding them to the deferred list. 3734 */ 3735 if (folio_order(folio) <= 1) 3736 return; 3737 3738 if (!partially_mapped && !split_underused_thp) 3739 return; 3740 3741 /* 3742 * Exclude swapcache: originally to avoid a corrupt deferred split 3743 * queue. Nowadays that is fully prevented by mem_cgroup_swapout(); 3744 * but if page reclaim is already handling the same folio, it is 3745 * unnecessary to handle it again in the shrinker, so excluding 3746 * swapcache here may still be a useful optimization. 3747 */ 3748 if (folio_test_swapcache(folio)) 3749 return; 3750 3751 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3752 if (partially_mapped) { 3753 if (!folio_test_partially_mapped(folio)) { 3754 folio_set_partially_mapped(folio); 3755 if (folio_test_pmd_mappable(folio)) 3756 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 3757 count_mthp_stat(folio_order(folio), MTHP_STAT_SPLIT_DEFERRED); 3758 mod_mthp_stat(folio_order(folio), MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, 1); 3759 3760 } 3761 } else { 3762 /* partially mapped folios cannot become non-partially mapped */ 3763 VM_WARN_ON_FOLIO(folio_test_partially_mapped(folio), folio); 3764 } 3765 if (list_empty(&folio->_deferred_list)) { 3766 list_add_tail(&folio->_deferred_list, &ds_queue->split_queue); 3767 ds_queue->split_queue_len++; 3768 #ifdef CONFIG_MEMCG 3769 if (memcg) 3770 set_shrinker_bit(memcg, folio_nid(folio), 3771 deferred_split_shrinker->id); 3772 #endif 3773 } 3774 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3775 } 3776 3777 static unsigned long deferred_split_count(struct shrinker *shrink, 3778 struct shrink_control *sc) 3779 { 3780 struct pglist_data *pgdata = NODE_DATA(sc->nid); 3781 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 3782 3783 #ifdef CONFIG_MEMCG 3784 if (sc->memcg) 3785 ds_queue = &sc->memcg->deferred_split_queue; 3786 #endif 3787 return READ_ONCE(ds_queue->split_queue_len); 3788 } 3789 3790 static bool thp_underused(struct folio *folio) 3791 { 3792 int num_zero_pages = 0, num_filled_pages = 0; 3793 void *kaddr; 3794 int i; 3795 3796 if (khugepaged_max_ptes_none == HPAGE_PMD_NR - 1) 3797 return false; 3798 3799 for (i = 0; i < folio_nr_pages(folio); i++) { 3800 kaddr = kmap_local_folio(folio, i * PAGE_SIZE); 3801 if (!memchr_inv(kaddr, 0, PAGE_SIZE)) { 3802 num_zero_pages++; 3803 if (num_zero_pages > khugepaged_max_ptes_none) { 3804 kunmap_local(kaddr); 3805 return true; 3806 } 3807 } else { 3808 /* 3809 * Another path for early exit once the number 3810 * of non-zero filled pages exceeds threshold. 3811 */ 3812 num_filled_pages++; 3813 if (num_filled_pages >= HPAGE_PMD_NR - khugepaged_max_ptes_none) { 3814 kunmap_local(kaddr); 3815 return false; 3816 } 3817 } 3818 kunmap_local(kaddr); 3819 } 3820 return false; 3821 } 3822 3823 static unsigned long deferred_split_scan(struct shrinker *shrink, 3824 struct shrink_control *sc) 3825 { 3826 struct pglist_data *pgdata = NODE_DATA(sc->nid); 3827 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 3828 unsigned long flags; 3829 LIST_HEAD(list); 3830 struct folio *folio, *next, *prev = NULL; 3831 int split = 0, removed = 0; 3832 3833 #ifdef CONFIG_MEMCG 3834 if (sc->memcg) 3835 ds_queue = &sc->memcg->deferred_split_queue; 3836 #endif 3837 3838 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3839 /* Take pin on all head pages to avoid freeing them under us */ 3840 list_for_each_entry_safe(folio, next, &ds_queue->split_queue, 3841 _deferred_list) { 3842 if (folio_try_get(folio)) { 3843 list_move(&folio->_deferred_list, &list); 3844 } else { 3845 /* We lost race with folio_put() */ 3846 if (folio_test_partially_mapped(folio)) { 3847 folio_clear_partially_mapped(folio); 3848 mod_mthp_stat(folio_order(folio), 3849 MTHP_STAT_NR_ANON_PARTIALLY_MAPPED, -1); 3850 } 3851 list_del_init(&folio->_deferred_list); 3852 ds_queue->split_queue_len--; 3853 } 3854 if (!--sc->nr_to_scan) 3855 break; 3856 } 3857 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3858 3859 list_for_each_entry_safe(folio, next, &list, _deferred_list) { 3860 bool did_split = false; 3861 bool underused = false; 3862 3863 if (!folio_test_partially_mapped(folio)) { 3864 underused = thp_underused(folio); 3865 if (!underused) 3866 goto next; 3867 } 3868 if (!folio_trylock(folio)) 3869 goto next; 3870 if (!split_folio(folio)) { 3871 did_split = true; 3872 if (underused) 3873 count_vm_event(THP_UNDERUSED_SPLIT_PAGE); 3874 split++; 3875 } 3876 folio_unlock(folio); 3877 next: 3878 /* 3879 * split_folio() removes folio from list on success. 3880 * Only add back to the queue if folio is partially mapped. 3881 * If thp_underused returns false, or if split_folio fails 3882 * in the case it was underused, then consider it used and 3883 * don't add it back to split_queue. 3884 */ 3885 if (did_split) { 3886 ; /* folio already removed from list */ 3887 } else if (!folio_test_partially_mapped(folio)) { 3888 list_del_init(&folio->_deferred_list); 3889 removed++; 3890 } else { 3891 /* 3892 * That unlocked list_del_init() above would be unsafe, 3893 * unless its folio is separated from any earlier folios 3894 * left on the list (which may be concurrently unqueued) 3895 * by one safe folio with refcount still raised. 3896 */ 3897 swap(folio, prev); 3898 } 3899 if (folio) 3900 folio_put(folio); 3901 } 3902 3903 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3904 list_splice_tail(&list, &ds_queue->split_queue); 3905 ds_queue->split_queue_len -= removed; 3906 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3907 3908 if (prev) 3909 folio_put(prev); 3910 3911 /* 3912 * Stop shrinker if we didn't split any page, but the queue is empty. 3913 * This can happen if pages were freed under us. 3914 */ 3915 if (!split && list_empty(&ds_queue->split_queue)) 3916 return SHRINK_STOP; 3917 return split; 3918 } 3919 3920 #ifdef CONFIG_DEBUG_FS 3921 static void split_huge_pages_all(void) 3922 { 3923 struct zone *zone; 3924 struct page *page; 3925 struct folio *folio; 3926 unsigned long pfn, max_zone_pfn; 3927 unsigned long total = 0, split = 0; 3928 3929 pr_debug("Split all THPs\n"); 3930 for_each_zone(zone) { 3931 if (!managed_zone(zone)) 3932 continue; 3933 max_zone_pfn = zone_end_pfn(zone); 3934 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 3935 int nr_pages; 3936 3937 page = pfn_to_online_page(pfn); 3938 if (!page || PageTail(page)) 3939 continue; 3940 folio = page_folio(page); 3941 if (!folio_try_get(folio)) 3942 continue; 3943 3944 if (unlikely(page_folio(page) != folio)) 3945 goto next; 3946 3947 if (zone != folio_zone(folio)) 3948 goto next; 3949 3950 if (!folio_test_large(folio) 3951 || folio_test_hugetlb(folio) 3952 || !folio_test_lru(folio)) 3953 goto next; 3954 3955 total++; 3956 folio_lock(folio); 3957 nr_pages = folio_nr_pages(folio); 3958 if (!split_folio(folio)) 3959 split++; 3960 pfn += nr_pages - 1; 3961 folio_unlock(folio); 3962 next: 3963 folio_put(folio); 3964 cond_resched(); 3965 } 3966 } 3967 3968 pr_debug("%lu of %lu THP split\n", split, total); 3969 } 3970 3971 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) 3972 { 3973 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || 3974 is_vm_hugetlb_page(vma); 3975 } 3976 3977 static int split_huge_pages_pid(int pid, unsigned long vaddr_start, 3978 unsigned long vaddr_end, unsigned int new_order) 3979 { 3980 int ret = 0; 3981 struct task_struct *task; 3982 struct mm_struct *mm; 3983 unsigned long total = 0, split = 0; 3984 unsigned long addr; 3985 3986 vaddr_start &= PAGE_MASK; 3987 vaddr_end &= PAGE_MASK; 3988 3989 task = find_get_task_by_vpid(pid); 3990 if (!task) { 3991 ret = -ESRCH; 3992 goto out; 3993 } 3994 3995 /* Find the mm_struct */ 3996 mm = get_task_mm(task); 3997 put_task_struct(task); 3998 3999 if (!mm) { 4000 ret = -EINVAL; 4001 goto out; 4002 } 4003 4004 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n", 4005 pid, vaddr_start, vaddr_end); 4006 4007 mmap_read_lock(mm); 4008 /* 4009 * always increase addr by PAGE_SIZE, since we could have a PTE page 4010 * table filled with PTE-mapped THPs, each of which is distinct. 4011 */ 4012 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { 4013 struct vm_area_struct *vma = vma_lookup(mm, addr); 4014 struct folio_walk fw; 4015 struct folio *folio; 4016 struct address_space *mapping; 4017 unsigned int target_order = new_order; 4018 4019 if (!vma) 4020 break; 4021 4022 /* skip special VMA and hugetlb VMA */ 4023 if (vma_not_suitable_for_thp_split(vma)) { 4024 addr = vma->vm_end; 4025 continue; 4026 } 4027 4028 folio = folio_walk_start(&fw, vma, addr, 0); 4029 if (!folio) 4030 continue; 4031 4032 if (!is_transparent_hugepage(folio)) 4033 goto next; 4034 4035 if (!folio_test_anon(folio)) { 4036 mapping = folio->mapping; 4037 target_order = max(new_order, 4038 mapping_min_folio_order(mapping)); 4039 } 4040 4041 if (target_order >= folio_order(folio)) 4042 goto next; 4043 4044 total++; 4045 /* 4046 * For folios with private, split_huge_page_to_list_to_order() 4047 * will try to drop it before split and then check if the folio 4048 * can be split or not. So skip the check here. 4049 */ 4050 if (!folio_test_private(folio) && 4051 !can_split_folio(folio, 0, NULL)) 4052 goto next; 4053 4054 if (!folio_trylock(folio)) 4055 goto next; 4056 folio_get(folio); 4057 folio_walk_end(&fw, vma); 4058 4059 if (!folio_test_anon(folio) && folio->mapping != mapping) 4060 goto unlock; 4061 4062 if (!split_folio_to_order(folio, target_order)) 4063 split++; 4064 4065 unlock: 4066 4067 folio_unlock(folio); 4068 folio_put(folio); 4069 4070 cond_resched(); 4071 continue; 4072 next: 4073 folio_walk_end(&fw, vma); 4074 cond_resched(); 4075 } 4076 mmap_read_unlock(mm); 4077 mmput(mm); 4078 4079 pr_debug("%lu of %lu THP split\n", split, total); 4080 4081 out: 4082 return ret; 4083 } 4084 4085 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, 4086 pgoff_t off_end, unsigned int new_order) 4087 { 4088 struct filename *file; 4089 struct file *candidate; 4090 struct address_space *mapping; 4091 int ret = -EINVAL; 4092 pgoff_t index; 4093 int nr_pages = 1; 4094 unsigned long total = 0, split = 0; 4095 unsigned int min_order; 4096 unsigned int target_order; 4097 4098 file = getname_kernel(file_path); 4099 if (IS_ERR(file)) 4100 return ret; 4101 4102 candidate = file_open_name(file, O_RDONLY, 0); 4103 if (IS_ERR(candidate)) 4104 goto out; 4105 4106 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", 4107 file_path, off_start, off_end); 4108 4109 mapping = candidate->f_mapping; 4110 min_order = mapping_min_folio_order(mapping); 4111 target_order = max(new_order, min_order); 4112 4113 for (index = off_start; index < off_end; index += nr_pages) { 4114 struct folio *folio = filemap_get_folio(mapping, index); 4115 4116 nr_pages = 1; 4117 if (IS_ERR(folio)) 4118 continue; 4119 4120 if (!folio_test_large(folio)) 4121 goto next; 4122 4123 total++; 4124 nr_pages = folio_nr_pages(folio); 4125 4126 if (target_order >= folio_order(folio)) 4127 goto next; 4128 4129 if (!folio_trylock(folio)) 4130 goto next; 4131 4132 if (folio->mapping != mapping) 4133 goto unlock; 4134 4135 if (!split_folio_to_order(folio, target_order)) 4136 split++; 4137 4138 unlock: 4139 folio_unlock(folio); 4140 next: 4141 folio_put(folio); 4142 cond_resched(); 4143 } 4144 4145 filp_close(candidate, NULL); 4146 ret = 0; 4147 4148 pr_debug("%lu of %lu file-backed THP split\n", split, total); 4149 out: 4150 putname(file); 4151 return ret; 4152 } 4153 4154 #define MAX_INPUT_BUF_SZ 255 4155 4156 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, 4157 size_t count, loff_t *ppops) 4158 { 4159 static DEFINE_MUTEX(split_debug_mutex); 4160 ssize_t ret; 4161 /* 4162 * hold pid, start_vaddr, end_vaddr, new_order or 4163 * file_path, off_start, off_end, new_order 4164 */ 4165 char input_buf[MAX_INPUT_BUF_SZ]; 4166 int pid; 4167 unsigned long vaddr_start, vaddr_end; 4168 unsigned int new_order = 0; 4169 4170 ret = mutex_lock_interruptible(&split_debug_mutex); 4171 if (ret) 4172 return ret; 4173 4174 ret = -EFAULT; 4175 4176 memset(input_buf, 0, MAX_INPUT_BUF_SZ); 4177 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) 4178 goto out; 4179 4180 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; 4181 4182 if (input_buf[0] == '/') { 4183 char *tok; 4184 char *tok_buf = input_buf; 4185 char file_path[MAX_INPUT_BUF_SZ]; 4186 pgoff_t off_start = 0, off_end = 0; 4187 size_t input_len = strlen(input_buf); 4188 4189 tok = strsep(&tok_buf, ","); 4190 if (tok && tok_buf) { 4191 strscpy(file_path, tok); 4192 } else { 4193 ret = -EINVAL; 4194 goto out; 4195 } 4196 4197 ret = sscanf(tok_buf, "0x%lx,0x%lx,%d", &off_start, 4198 &off_end, &new_order); 4199 if (ret != 2 && ret != 3) { 4200 ret = -EINVAL; 4201 goto out; 4202 } 4203 ret = split_huge_pages_in_file(file_path, off_start, off_end, new_order); 4204 if (!ret) 4205 ret = input_len; 4206 4207 goto out; 4208 } 4209 4210 ret = sscanf(input_buf, "%d,0x%lx,0x%lx,%d", &pid, &vaddr_start, &vaddr_end, &new_order); 4211 if (ret == 1 && pid == 1) { 4212 split_huge_pages_all(); 4213 ret = strlen(input_buf); 4214 goto out; 4215 } else if (ret != 3 && ret != 4) { 4216 ret = -EINVAL; 4217 goto out; 4218 } 4219 4220 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end, new_order); 4221 if (!ret) 4222 ret = strlen(input_buf); 4223 out: 4224 mutex_unlock(&split_debug_mutex); 4225 return ret; 4226 4227 } 4228 4229 static const struct file_operations split_huge_pages_fops = { 4230 .owner = THIS_MODULE, 4231 .write = split_huge_pages_write, 4232 }; 4233 4234 static int __init split_huge_pages_debugfs(void) 4235 { 4236 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 4237 &split_huge_pages_fops); 4238 return 0; 4239 } 4240 late_initcall(split_huge_pages_debugfs); 4241 #endif 4242 4243 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 4244 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 4245 struct page *page) 4246 { 4247 struct folio *folio = page_folio(page); 4248 struct vm_area_struct *vma = pvmw->vma; 4249 struct mm_struct *mm = vma->vm_mm; 4250 unsigned long address = pvmw->address; 4251 bool anon_exclusive; 4252 pmd_t pmdval; 4253 swp_entry_t entry; 4254 pmd_t pmdswp; 4255 4256 if (!(pvmw->pmd && !pvmw->pte)) 4257 return 0; 4258 4259 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 4260 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 4261 4262 /* See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */ 4263 anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(page); 4264 if (anon_exclusive && folio_try_share_anon_rmap_pmd(folio, page)) { 4265 set_pmd_at(mm, address, pvmw->pmd, pmdval); 4266 return -EBUSY; 4267 } 4268 4269 if (pmd_dirty(pmdval)) 4270 folio_mark_dirty(folio); 4271 if (pmd_write(pmdval)) 4272 entry = make_writable_migration_entry(page_to_pfn(page)); 4273 else if (anon_exclusive) 4274 entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); 4275 else 4276 entry = make_readable_migration_entry(page_to_pfn(page)); 4277 if (pmd_young(pmdval)) 4278 entry = make_migration_entry_young(entry); 4279 if (pmd_dirty(pmdval)) 4280 entry = make_migration_entry_dirty(entry); 4281 pmdswp = swp_entry_to_pmd(entry); 4282 if (pmd_soft_dirty(pmdval)) 4283 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 4284 if (pmd_uffd_wp(pmdval)) 4285 pmdswp = pmd_swp_mkuffd_wp(pmdswp); 4286 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 4287 folio_remove_rmap_pmd(folio, page, vma); 4288 folio_put(folio); 4289 trace_set_migration_pmd(address, pmd_val(pmdswp)); 4290 4291 return 0; 4292 } 4293 4294 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 4295 { 4296 struct folio *folio = page_folio(new); 4297 struct vm_area_struct *vma = pvmw->vma; 4298 struct mm_struct *mm = vma->vm_mm; 4299 unsigned long address = pvmw->address; 4300 unsigned long haddr = address & HPAGE_PMD_MASK; 4301 pmd_t pmde; 4302 swp_entry_t entry; 4303 4304 if (!(pvmw->pmd && !pvmw->pte)) 4305 return; 4306 4307 entry = pmd_to_swp_entry(*pvmw->pmd); 4308 folio_get(folio); 4309 pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot)); 4310 if (pmd_swp_soft_dirty(*pvmw->pmd)) 4311 pmde = pmd_mksoft_dirty(pmde); 4312 if (is_writable_migration_entry(entry)) 4313 pmde = pmd_mkwrite(pmde, vma); 4314 if (pmd_swp_uffd_wp(*pvmw->pmd)) 4315 pmde = pmd_mkuffd_wp(pmde); 4316 if (!is_migration_entry_young(entry)) 4317 pmde = pmd_mkold(pmde); 4318 /* NOTE: this may contain setting soft-dirty on some archs */ 4319 if (folio_test_dirty(folio) && is_migration_entry_dirty(entry)) 4320 pmde = pmd_mkdirty(pmde); 4321 4322 if (folio_test_anon(folio)) { 4323 rmap_t rmap_flags = RMAP_NONE; 4324 4325 if (!is_readable_migration_entry(entry)) 4326 rmap_flags |= RMAP_EXCLUSIVE; 4327 4328 folio_add_anon_rmap_pmd(folio, new, vma, haddr, rmap_flags); 4329 } else { 4330 folio_add_file_rmap_pmd(folio, new, vma); 4331 } 4332 VM_BUG_ON(pmd_write(pmde) && folio_test_anon(folio) && !PageAnonExclusive(new)); 4333 set_pmd_at(mm, haddr, pvmw->pmd, pmde); 4334 4335 /* No need to invalidate - it was non-present before */ 4336 update_mmu_cache_pmd(vma, address, pvmw->pmd); 4337 trace_remove_migration_pmd(address, pmd_val(pmde)); 4338 } 4339 #endif 4340