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/coredump.h> 12 #include <linux/sched/numa_balancing.h> 13 #include <linux/highmem.h> 14 #include <linux/hugetlb.h> 15 #include <linux/mmu_notifier.h> 16 #include <linux/rmap.h> 17 #include <linux/swap.h> 18 #include <linux/shrinker.h> 19 #include <linux/mm_inline.h> 20 #include <linux/swapops.h> 21 #include <linux/backing-dev.h> 22 #include <linux/dax.h> 23 #include <linux/mm_types.h> 24 #include <linux/khugepaged.h> 25 #include <linux/freezer.h> 26 #include <linux/pfn_t.h> 27 #include <linux/mman.h> 28 #include <linux/memremap.h> 29 #include <linux/pagemap.h> 30 #include <linux/debugfs.h> 31 #include <linux/migrate.h> 32 #include <linux/hashtable.h> 33 #include <linux/userfaultfd_k.h> 34 #include <linux/page_idle.h> 35 #include <linux/shmem_fs.h> 36 #include <linux/oom.h> 37 #include <linux/numa.h> 38 #include <linux/page_owner.h> 39 #include <linux/sched/sysctl.h> 40 #include <linux/memory-tiers.h> 41 #include <linux/compat.h> 42 #include <linux/pgalloc_tag.h> 43 #include <linux/pagewalk.h> 44 45 #include <asm/tlb.h> 46 #include <asm/pgalloc.h> 47 #include "internal.h" 48 #include "swap.h" 49 50 #define CREATE_TRACE_POINTS 51 #include <trace/events/thp.h> 52 53 /* 54 * By default, transparent hugepage support is disabled in order to avoid 55 * risking an increased memory footprint for applications that are not 56 * guaranteed to benefit from it. When transparent hugepage support is 57 * enabled, it is for all mappings, and khugepaged scans all mappings. 58 * Defrag is invoked by khugepaged hugepage allocations and by page faults 59 * for all hugepage allocations. 60 */ 61 unsigned long transparent_hugepage_flags __read_mostly = 62 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 63 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 64 #endif 65 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 66 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 67 #endif 68 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 69 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 70 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 71 72 static struct shrinker *deferred_split_shrinker; 73 static unsigned long deferred_split_count(struct shrinker *shrink, 74 struct shrink_control *sc); 75 static unsigned long deferred_split_scan(struct shrinker *shrink, 76 struct shrink_control *sc); 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 85 unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, 86 unsigned long vm_flags, 87 unsigned long tva_flags, 88 unsigned long orders) 89 { 90 bool smaps = tva_flags & TVA_SMAPS; 91 bool in_pf = tva_flags & TVA_IN_PF; 92 bool enforce_sysfs = tva_flags & TVA_ENFORCE_SYSFS; 93 unsigned long supported_orders; 94 95 /* Check the intersection of requested and supported orders. */ 96 if (vma_is_anonymous(vma)) 97 supported_orders = THP_ORDERS_ALL_ANON; 98 else if (vma_is_dax(vma)) 99 supported_orders = THP_ORDERS_ALL_FILE_DAX; 100 else 101 supported_orders = THP_ORDERS_ALL_FILE_DEFAULT; 102 103 orders &= supported_orders; 104 if (!orders) 105 return 0; 106 107 if (!vma->vm_mm) /* vdso */ 108 return 0; 109 110 /* 111 * Explicitly disabled through madvise or prctl, or some 112 * architectures may disable THP for some mappings, for 113 * example, s390 kvm. 114 * */ 115 if ((vm_flags & VM_NOHUGEPAGE) || 116 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) 117 return 0; 118 /* 119 * If the hardware/firmware marked hugepage support disabled. 120 */ 121 if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED)) 122 return 0; 123 124 /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ 125 if (vma_is_dax(vma)) 126 return in_pf ? orders : 0; 127 128 /* 129 * khugepaged special VMA and hugetlb VMA. 130 * Must be checked after dax since some dax mappings may have 131 * VM_MIXEDMAP set. 132 */ 133 if (!in_pf && !smaps && (vm_flags & VM_NO_KHUGEPAGED)) 134 return 0; 135 136 /* 137 * Check alignment for file vma and size for both file and anon vma by 138 * filtering out the unsuitable orders. 139 * 140 * Skip the check for page fault. Huge fault does the check in fault 141 * handlers. 142 */ 143 if (!in_pf) { 144 int order = highest_order(orders); 145 unsigned long addr; 146 147 while (orders) { 148 addr = vma->vm_end - (PAGE_SIZE << order); 149 if (thp_vma_suitable_order(vma, addr, order)) 150 break; 151 order = next_order(&orders, order); 152 } 153 154 if (!orders) 155 return 0; 156 } 157 158 /* 159 * Enabled via shmem mount options or sysfs settings. 160 * Must be done before hugepage flags check since shmem has its 161 * own flags. 162 */ 163 if (!in_pf && shmem_file(vma->vm_file)) 164 return shmem_allowable_huge_orders(file_inode(vma->vm_file), 165 vma, vma->vm_pgoff, 166 !enforce_sysfs); 167 168 if (!vma_is_anonymous(vma)) { 169 /* 170 * Enforce sysfs THP requirements as necessary. Anonymous vmas 171 * were already handled in thp_vma_allowable_orders(). 172 */ 173 if (enforce_sysfs && 174 (!hugepage_global_enabled() || (!(vm_flags & VM_HUGEPAGE) && 175 !hugepage_global_always()))) 176 return 0; 177 178 /* 179 * Trust that ->huge_fault() handlers know what they are doing 180 * in fault path. 181 */ 182 if (((in_pf || smaps)) && vma->vm_ops->huge_fault) 183 return orders; 184 /* Only regular file is valid in collapse path */ 185 if (((!in_pf || smaps)) && file_thp_enabled(vma)) 186 return orders; 187 return 0; 188 } 189 190 if (vma_is_temporary_stack(vma)) 191 return 0; 192 193 /* 194 * THPeligible bit of smaps should show 1 for proper VMAs even 195 * though anon_vma is not initialized yet. 196 * 197 * Allow page fault since anon_vma may be not initialized until 198 * the first page fault. 199 */ 200 if (!vma->anon_vma) 201 return (smaps || in_pf) ? orders : 0; 202 203 return orders; 204 } 205 206 static bool get_huge_zero_page(void) 207 { 208 struct folio *zero_folio; 209 retry: 210 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 211 return true; 212 213 zero_folio = folio_alloc((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 214 HPAGE_PMD_ORDER); 215 if (!zero_folio) { 216 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 217 return false; 218 } 219 preempt_disable(); 220 if (cmpxchg(&huge_zero_folio, NULL, zero_folio)) { 221 preempt_enable(); 222 folio_put(zero_folio); 223 goto retry; 224 } 225 WRITE_ONCE(huge_zero_pfn, folio_pfn(zero_folio)); 226 227 /* We take additional reference here. It will be put back by shrinker */ 228 atomic_set(&huge_zero_refcount, 2); 229 preempt_enable(); 230 count_vm_event(THP_ZERO_PAGE_ALLOC); 231 return true; 232 } 233 234 static void put_huge_zero_page(void) 235 { 236 /* 237 * Counter should never go to zero here. Only shrinker can put 238 * last reference. 239 */ 240 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 241 } 242 243 struct folio *mm_get_huge_zero_folio(struct mm_struct *mm) 244 { 245 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 246 return READ_ONCE(huge_zero_folio); 247 248 if (!get_huge_zero_page()) 249 return NULL; 250 251 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 252 put_huge_zero_page(); 253 254 return READ_ONCE(huge_zero_folio); 255 } 256 257 void mm_put_huge_zero_folio(struct mm_struct *mm) 258 { 259 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 260 put_huge_zero_page(); 261 } 262 263 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 264 struct shrink_control *sc) 265 { 266 /* we can free zero page only if last reference remains */ 267 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 268 } 269 270 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 271 struct shrink_control *sc) 272 { 273 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 274 struct folio *zero_folio = xchg(&huge_zero_folio, NULL); 275 BUG_ON(zero_folio == NULL); 276 WRITE_ONCE(huge_zero_pfn, ~0UL); 277 folio_put(zero_folio); 278 return HPAGE_PMD_NR; 279 } 280 281 return 0; 282 } 283 284 static struct shrinker *huge_zero_page_shrinker; 285 286 #ifdef CONFIG_SYSFS 287 static ssize_t enabled_show(struct kobject *kobj, 288 struct kobj_attribute *attr, char *buf) 289 { 290 const char *output; 291 292 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 293 output = "[always] madvise never"; 294 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 295 &transparent_hugepage_flags)) 296 output = "always [madvise] never"; 297 else 298 output = "always madvise [never]"; 299 300 return sysfs_emit(buf, "%s\n", output); 301 } 302 303 static ssize_t enabled_store(struct kobject *kobj, 304 struct kobj_attribute *attr, 305 const char *buf, size_t count) 306 { 307 ssize_t ret = count; 308 309 if (sysfs_streq(buf, "always")) { 310 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 311 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 312 } else if (sysfs_streq(buf, "madvise")) { 313 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 314 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 315 } else if (sysfs_streq(buf, "never")) { 316 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 317 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 318 } else 319 ret = -EINVAL; 320 321 if (ret > 0) { 322 int err = start_stop_khugepaged(); 323 if (err) 324 ret = err; 325 } 326 return ret; 327 } 328 329 static struct kobj_attribute enabled_attr = __ATTR_RW(enabled); 330 331 ssize_t single_hugepage_flag_show(struct kobject *kobj, 332 struct kobj_attribute *attr, char *buf, 333 enum transparent_hugepage_flag flag) 334 { 335 return sysfs_emit(buf, "%d\n", 336 !!test_bit(flag, &transparent_hugepage_flags)); 337 } 338 339 ssize_t single_hugepage_flag_store(struct kobject *kobj, 340 struct kobj_attribute *attr, 341 const char *buf, size_t count, 342 enum transparent_hugepage_flag flag) 343 { 344 unsigned long value; 345 int ret; 346 347 ret = kstrtoul(buf, 10, &value); 348 if (ret < 0) 349 return ret; 350 if (value > 1) 351 return -EINVAL; 352 353 if (value) 354 set_bit(flag, &transparent_hugepage_flags); 355 else 356 clear_bit(flag, &transparent_hugepage_flags); 357 358 return count; 359 } 360 361 static ssize_t defrag_show(struct kobject *kobj, 362 struct kobj_attribute *attr, char *buf) 363 { 364 const char *output; 365 366 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 367 &transparent_hugepage_flags)) 368 output = "[always] defer defer+madvise madvise never"; 369 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 370 &transparent_hugepage_flags)) 371 output = "always [defer] defer+madvise madvise never"; 372 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 373 &transparent_hugepage_flags)) 374 output = "always defer [defer+madvise] madvise never"; 375 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 376 &transparent_hugepage_flags)) 377 output = "always defer defer+madvise [madvise] never"; 378 else 379 output = "always defer defer+madvise madvise [never]"; 380 381 return sysfs_emit(buf, "%s\n", output); 382 } 383 384 static ssize_t defrag_store(struct kobject *kobj, 385 struct kobj_attribute *attr, 386 const char *buf, size_t count) 387 { 388 if (sysfs_streq(buf, "always")) { 389 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 390 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 391 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 392 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 393 } else if (sysfs_streq(buf, "defer+madvise")) { 394 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 395 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 396 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 397 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 398 } else if (sysfs_streq(buf, "defer")) { 399 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 400 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 401 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 402 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 403 } else if (sysfs_streq(buf, "madvise")) { 404 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 405 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 406 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 407 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 408 } else if (sysfs_streq(buf, "never")) { 409 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 410 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 411 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 412 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 413 } else 414 return -EINVAL; 415 416 return count; 417 } 418 static struct kobj_attribute defrag_attr = __ATTR_RW(defrag); 419 420 static ssize_t use_zero_page_show(struct kobject *kobj, 421 struct kobj_attribute *attr, char *buf) 422 { 423 return single_hugepage_flag_show(kobj, attr, buf, 424 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 425 } 426 static ssize_t use_zero_page_store(struct kobject *kobj, 427 struct kobj_attribute *attr, const char *buf, size_t count) 428 { 429 return single_hugepage_flag_store(kobj, attr, buf, count, 430 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 431 } 432 static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page); 433 434 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 435 struct kobj_attribute *attr, char *buf) 436 { 437 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); 438 } 439 static struct kobj_attribute hpage_pmd_size_attr = 440 __ATTR_RO(hpage_pmd_size); 441 442 static struct attribute *hugepage_attr[] = { 443 &enabled_attr.attr, 444 &defrag_attr.attr, 445 &use_zero_page_attr.attr, 446 &hpage_pmd_size_attr.attr, 447 #ifdef CONFIG_SHMEM 448 &shmem_enabled_attr.attr, 449 #endif 450 NULL, 451 }; 452 453 static const struct attribute_group hugepage_attr_group = { 454 .attrs = hugepage_attr, 455 }; 456 457 static void hugepage_exit_sysfs(struct kobject *hugepage_kobj); 458 static void thpsize_release(struct kobject *kobj); 459 static DEFINE_SPINLOCK(huge_anon_orders_lock); 460 static LIST_HEAD(thpsize_list); 461 462 static ssize_t thpsize_enabled_show(struct kobject *kobj, 463 struct kobj_attribute *attr, char *buf) 464 { 465 int order = to_thpsize(kobj)->order; 466 const char *output; 467 468 if (test_bit(order, &huge_anon_orders_always)) 469 output = "[always] inherit madvise never"; 470 else if (test_bit(order, &huge_anon_orders_inherit)) 471 output = "always [inherit] madvise never"; 472 else if (test_bit(order, &huge_anon_orders_madvise)) 473 output = "always inherit [madvise] never"; 474 else 475 output = "always inherit madvise [never]"; 476 477 return sysfs_emit(buf, "%s\n", output); 478 } 479 480 static ssize_t thpsize_enabled_store(struct kobject *kobj, 481 struct kobj_attribute *attr, 482 const char *buf, size_t count) 483 { 484 int order = to_thpsize(kobj)->order; 485 ssize_t ret = count; 486 487 if (sysfs_streq(buf, "always")) { 488 spin_lock(&huge_anon_orders_lock); 489 clear_bit(order, &huge_anon_orders_inherit); 490 clear_bit(order, &huge_anon_orders_madvise); 491 set_bit(order, &huge_anon_orders_always); 492 spin_unlock(&huge_anon_orders_lock); 493 } else if (sysfs_streq(buf, "inherit")) { 494 spin_lock(&huge_anon_orders_lock); 495 clear_bit(order, &huge_anon_orders_always); 496 clear_bit(order, &huge_anon_orders_madvise); 497 set_bit(order, &huge_anon_orders_inherit); 498 spin_unlock(&huge_anon_orders_lock); 499 } else if (sysfs_streq(buf, "madvise")) { 500 spin_lock(&huge_anon_orders_lock); 501 clear_bit(order, &huge_anon_orders_always); 502 clear_bit(order, &huge_anon_orders_inherit); 503 set_bit(order, &huge_anon_orders_madvise); 504 spin_unlock(&huge_anon_orders_lock); 505 } else if (sysfs_streq(buf, "never")) { 506 spin_lock(&huge_anon_orders_lock); 507 clear_bit(order, &huge_anon_orders_always); 508 clear_bit(order, &huge_anon_orders_inherit); 509 clear_bit(order, &huge_anon_orders_madvise); 510 spin_unlock(&huge_anon_orders_lock); 511 } else 512 ret = -EINVAL; 513 514 if (ret > 0) { 515 int err; 516 517 err = start_stop_khugepaged(); 518 if (err) 519 ret = err; 520 } 521 return ret; 522 } 523 524 static struct kobj_attribute thpsize_enabled_attr = 525 __ATTR(enabled, 0644, thpsize_enabled_show, thpsize_enabled_store); 526 527 static struct attribute *thpsize_attrs[] = { 528 &thpsize_enabled_attr.attr, 529 #ifdef CONFIG_SHMEM 530 &thpsize_shmem_enabled_attr.attr, 531 #endif 532 NULL, 533 }; 534 535 static const struct attribute_group thpsize_attr_group = { 536 .attrs = thpsize_attrs, 537 }; 538 539 static const struct kobj_type thpsize_ktype = { 540 .release = &thpsize_release, 541 .sysfs_ops = &kobj_sysfs_ops, 542 }; 543 544 DEFINE_PER_CPU(struct mthp_stat, mthp_stats) = {{{0}}}; 545 546 static unsigned long sum_mthp_stat(int order, enum mthp_stat_item item) 547 { 548 unsigned long sum = 0; 549 int cpu; 550 551 for_each_possible_cpu(cpu) { 552 struct mthp_stat *this = &per_cpu(mthp_stats, cpu); 553 554 sum += this->stats[order][item]; 555 } 556 557 return sum; 558 } 559 560 #define DEFINE_MTHP_STAT_ATTR(_name, _index) \ 561 static ssize_t _name##_show(struct kobject *kobj, \ 562 struct kobj_attribute *attr, char *buf) \ 563 { \ 564 int order = to_thpsize(kobj)->order; \ 565 \ 566 return sysfs_emit(buf, "%lu\n", sum_mthp_stat(order, _index)); \ 567 } \ 568 static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 569 570 DEFINE_MTHP_STAT_ATTR(anon_fault_alloc, MTHP_STAT_ANON_FAULT_ALLOC); 571 DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK); 572 DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); 573 DEFINE_MTHP_STAT_ATTR(swpout, MTHP_STAT_SWPOUT); 574 DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK); 575 DEFINE_MTHP_STAT_ATTR(shmem_alloc, MTHP_STAT_SHMEM_ALLOC); 576 DEFINE_MTHP_STAT_ATTR(shmem_fallback, MTHP_STAT_SHMEM_FALLBACK); 577 DEFINE_MTHP_STAT_ATTR(shmem_fallback_charge, MTHP_STAT_SHMEM_FALLBACK_CHARGE); 578 DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT); 579 DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED); 580 DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED); 581 582 static struct attribute *stats_attrs[] = { 583 &anon_fault_alloc_attr.attr, 584 &anon_fault_fallback_attr.attr, 585 &anon_fault_fallback_charge_attr.attr, 586 &swpout_attr.attr, 587 &swpout_fallback_attr.attr, 588 &shmem_alloc_attr.attr, 589 &shmem_fallback_attr.attr, 590 &shmem_fallback_charge_attr.attr, 591 &split_attr.attr, 592 &split_failed_attr.attr, 593 &split_deferred_attr.attr, 594 NULL, 595 }; 596 597 static struct attribute_group stats_attr_group = { 598 .name = "stats", 599 .attrs = stats_attrs, 600 }; 601 602 static struct thpsize *thpsize_create(int order, struct kobject *parent) 603 { 604 unsigned long size = (PAGE_SIZE << order) / SZ_1K; 605 struct thpsize *thpsize; 606 int ret; 607 608 thpsize = kzalloc(sizeof(*thpsize), GFP_KERNEL); 609 if (!thpsize) 610 return ERR_PTR(-ENOMEM); 611 612 ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent, 613 "hugepages-%lukB", size); 614 if (ret) { 615 kfree(thpsize); 616 return ERR_PTR(ret); 617 } 618 619 ret = sysfs_create_group(&thpsize->kobj, &thpsize_attr_group); 620 if (ret) { 621 kobject_put(&thpsize->kobj); 622 return ERR_PTR(ret); 623 } 624 625 ret = sysfs_create_group(&thpsize->kobj, &stats_attr_group); 626 if (ret) { 627 kobject_put(&thpsize->kobj); 628 return ERR_PTR(ret); 629 } 630 631 thpsize->order = order; 632 return thpsize; 633 } 634 635 static void thpsize_release(struct kobject *kobj) 636 { 637 kfree(to_thpsize(kobj)); 638 } 639 640 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 641 { 642 int err; 643 struct thpsize *thpsize; 644 unsigned long orders; 645 int order; 646 647 /* 648 * Default to setting PMD-sized THP to inherit the global setting and 649 * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time 650 * constant so we have to do this here. 651 */ 652 huge_anon_orders_inherit = BIT(PMD_ORDER); 653 654 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 655 if (unlikely(!*hugepage_kobj)) { 656 pr_err("failed to create transparent hugepage kobject\n"); 657 return -ENOMEM; 658 } 659 660 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 661 if (err) { 662 pr_err("failed to register transparent hugepage group\n"); 663 goto delete_obj; 664 } 665 666 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 667 if (err) { 668 pr_err("failed to register transparent hugepage group\n"); 669 goto remove_hp_group; 670 } 671 672 orders = THP_ORDERS_ALL_ANON; 673 order = highest_order(orders); 674 while (orders) { 675 thpsize = thpsize_create(order, *hugepage_kobj); 676 if (IS_ERR(thpsize)) { 677 pr_err("failed to create thpsize for order %d\n", order); 678 err = PTR_ERR(thpsize); 679 goto remove_all; 680 } 681 list_add(&thpsize->node, &thpsize_list); 682 order = next_order(&orders, order); 683 } 684 685 return 0; 686 687 remove_all: 688 hugepage_exit_sysfs(*hugepage_kobj); 689 return err; 690 remove_hp_group: 691 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 692 delete_obj: 693 kobject_put(*hugepage_kobj); 694 return err; 695 } 696 697 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 698 { 699 struct thpsize *thpsize, *tmp; 700 701 list_for_each_entry_safe(thpsize, tmp, &thpsize_list, node) { 702 list_del(&thpsize->node); 703 kobject_put(&thpsize->kobj); 704 } 705 706 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 707 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 708 kobject_put(hugepage_kobj); 709 } 710 #else 711 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 712 { 713 return 0; 714 } 715 716 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 717 { 718 } 719 #endif /* CONFIG_SYSFS */ 720 721 static int __init thp_shrinker_init(void) 722 { 723 huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero"); 724 if (!huge_zero_page_shrinker) 725 return -ENOMEM; 726 727 deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE | 728 SHRINKER_MEMCG_AWARE | 729 SHRINKER_NONSLAB, 730 "thp-deferred_split"); 731 if (!deferred_split_shrinker) { 732 shrinker_free(huge_zero_page_shrinker); 733 return -ENOMEM; 734 } 735 736 huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count; 737 huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan; 738 shrinker_register(huge_zero_page_shrinker); 739 740 deferred_split_shrinker->count_objects = deferred_split_count; 741 deferred_split_shrinker->scan_objects = deferred_split_scan; 742 shrinker_register(deferred_split_shrinker); 743 744 return 0; 745 } 746 747 static void __init thp_shrinker_exit(void) 748 { 749 shrinker_free(huge_zero_page_shrinker); 750 shrinker_free(deferred_split_shrinker); 751 } 752 753 static int __init hugepage_init(void) 754 { 755 int err; 756 struct kobject *hugepage_kobj; 757 758 if (!has_transparent_hugepage()) { 759 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED; 760 return -EINVAL; 761 } 762 763 /* 764 * hugepages can't be allocated by the buddy allocator 765 */ 766 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER > MAX_PAGE_ORDER); 767 768 err = hugepage_init_sysfs(&hugepage_kobj); 769 if (err) 770 goto err_sysfs; 771 772 err = khugepaged_init(); 773 if (err) 774 goto err_slab; 775 776 err = thp_shrinker_init(); 777 if (err) 778 goto err_shrinker; 779 780 /* 781 * By default disable transparent hugepages on smaller systems, 782 * where the extra memory used could hurt more than TLB overhead 783 * is likely to save. The admin can still enable it through /sys. 784 */ 785 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 786 transparent_hugepage_flags = 0; 787 return 0; 788 } 789 790 err = start_stop_khugepaged(); 791 if (err) 792 goto err_khugepaged; 793 794 return 0; 795 err_khugepaged: 796 thp_shrinker_exit(); 797 err_shrinker: 798 khugepaged_destroy(); 799 err_slab: 800 hugepage_exit_sysfs(hugepage_kobj); 801 err_sysfs: 802 return err; 803 } 804 subsys_initcall(hugepage_init); 805 806 static int __init setup_transparent_hugepage(char *str) 807 { 808 int ret = 0; 809 if (!str) 810 goto out; 811 if (!strcmp(str, "always")) { 812 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 813 &transparent_hugepage_flags); 814 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 815 &transparent_hugepage_flags); 816 ret = 1; 817 } else if (!strcmp(str, "madvise")) { 818 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 819 &transparent_hugepage_flags); 820 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 821 &transparent_hugepage_flags); 822 ret = 1; 823 } else if (!strcmp(str, "never")) { 824 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 825 &transparent_hugepage_flags); 826 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 827 &transparent_hugepage_flags); 828 ret = 1; 829 } 830 out: 831 if (!ret) 832 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 833 return ret; 834 } 835 __setup("transparent_hugepage=", setup_transparent_hugepage); 836 837 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 838 { 839 if (likely(vma->vm_flags & VM_WRITE)) 840 pmd = pmd_mkwrite(pmd, vma); 841 return pmd; 842 } 843 844 #ifdef CONFIG_MEMCG 845 static inline 846 struct deferred_split *get_deferred_split_queue(struct folio *folio) 847 { 848 struct mem_cgroup *memcg = folio_memcg(folio); 849 struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); 850 851 if (memcg) 852 return &memcg->deferred_split_queue; 853 else 854 return &pgdat->deferred_split_queue; 855 } 856 #else 857 static inline 858 struct deferred_split *get_deferred_split_queue(struct folio *folio) 859 { 860 struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); 861 862 return &pgdat->deferred_split_queue; 863 } 864 #endif 865 866 static inline bool is_transparent_hugepage(const struct folio *folio) 867 { 868 if (!folio_test_large(folio)) 869 return false; 870 871 return is_huge_zero_folio(folio) || 872 folio_test_large_rmappable(folio); 873 } 874 875 static unsigned long __thp_get_unmapped_area(struct file *filp, 876 unsigned long addr, unsigned long len, 877 loff_t off, unsigned long flags, unsigned long size, 878 vm_flags_t vm_flags) 879 { 880 loff_t off_end = off + len; 881 loff_t off_align = round_up(off, size); 882 unsigned long len_pad, ret, off_sub; 883 884 if (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()) 885 return 0; 886 887 if (off_end <= off_align || (off_end - off_align) < size) 888 return 0; 889 890 len_pad = len + size; 891 if (len_pad < len || (off + len_pad) < off) 892 return 0; 893 894 ret = mm_get_unmapped_area_vmflags(current->mm, filp, addr, len_pad, 895 off >> PAGE_SHIFT, flags, vm_flags); 896 897 /* 898 * The failure might be due to length padding. The caller will retry 899 * without the padding. 900 */ 901 if (IS_ERR_VALUE(ret)) 902 return 0; 903 904 /* 905 * Do not try to align to THP boundary if allocation at the address 906 * hint succeeds. 907 */ 908 if (ret == addr) 909 return addr; 910 911 off_sub = (off - ret) & (size - 1); 912 913 if (test_bit(MMF_TOPDOWN, ¤t->mm->flags) && !off_sub) 914 return ret + size; 915 916 ret += off_sub; 917 return ret; 918 } 919 920 unsigned long thp_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, 921 unsigned long len, unsigned long pgoff, unsigned long flags, 922 vm_flags_t vm_flags) 923 { 924 unsigned long ret; 925 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 926 927 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE, vm_flags); 928 if (ret) 929 return ret; 930 931 return mm_get_unmapped_area_vmflags(current->mm, filp, addr, len, pgoff, flags, 932 vm_flags); 933 } 934 935 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 936 unsigned long len, unsigned long pgoff, unsigned long flags) 937 { 938 return thp_get_unmapped_area_vmflags(filp, addr, len, pgoff, flags, 0); 939 } 940 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 941 942 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 943 struct page *page, gfp_t gfp) 944 { 945 struct vm_area_struct *vma = vmf->vma; 946 struct folio *folio = page_folio(page); 947 pgtable_t pgtable; 948 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 949 vm_fault_t ret = 0; 950 951 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 952 953 if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) { 954 folio_put(folio); 955 count_vm_event(THP_FAULT_FALLBACK); 956 count_vm_event(THP_FAULT_FALLBACK_CHARGE); 957 count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK); 958 count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); 959 return VM_FAULT_FALLBACK; 960 } 961 folio_throttle_swaprate(folio, gfp); 962 963 pgtable = pte_alloc_one(vma->vm_mm); 964 if (unlikely(!pgtable)) { 965 ret = VM_FAULT_OOM; 966 goto release; 967 } 968 969 folio_zero_user(folio, vmf->address); 970 /* 971 * The memory barrier inside __folio_mark_uptodate makes sure that 972 * folio_zero_user writes become visible before the set_pmd_at() 973 * write. 974 */ 975 __folio_mark_uptodate(folio); 976 977 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 978 if (unlikely(!pmd_none(*vmf->pmd))) { 979 goto unlock_release; 980 } else { 981 pmd_t entry; 982 983 ret = check_stable_address_space(vma->vm_mm); 984 if (ret) 985 goto unlock_release; 986 987 /* Deliver the page fault to userland */ 988 if (userfaultfd_missing(vma)) { 989 spin_unlock(vmf->ptl); 990 folio_put(folio); 991 pte_free(vma->vm_mm, pgtable); 992 ret = handle_userfault(vmf, VM_UFFD_MISSING); 993 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 994 return ret; 995 } 996 997 entry = mk_huge_pmd(page, vma->vm_page_prot); 998 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 999 folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE); 1000 folio_add_lru_vma(folio, vma); 1001 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 1002 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 1003 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1004 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1005 mm_inc_nr_ptes(vma->vm_mm); 1006 spin_unlock(vmf->ptl); 1007 count_vm_event(THP_FAULT_ALLOC); 1008 count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC); 1009 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); 1010 } 1011 1012 return 0; 1013 unlock_release: 1014 spin_unlock(vmf->ptl); 1015 release: 1016 if (pgtable) 1017 pte_free(vma->vm_mm, pgtable); 1018 folio_put(folio); 1019 return ret; 1020 1021 } 1022 1023 /* 1024 * always: directly stall for all thp allocations 1025 * defer: wake kswapd and fail if not immediately available 1026 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 1027 * fail if not immediately available 1028 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 1029 * available 1030 * never: never stall for any thp allocation 1031 */ 1032 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) 1033 { 1034 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); 1035 1036 /* Always do synchronous compaction */ 1037 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 1038 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 1039 1040 /* Kick kcompactd and fail quickly */ 1041 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 1042 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; 1043 1044 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 1045 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 1046 return GFP_TRANSHUGE_LIGHT | 1047 (vma_madvised ? __GFP_DIRECT_RECLAIM : 1048 __GFP_KSWAPD_RECLAIM); 1049 1050 /* Only do synchronous compaction if madvised */ 1051 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 1052 return GFP_TRANSHUGE_LIGHT | 1053 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 1054 1055 return GFP_TRANSHUGE_LIGHT; 1056 } 1057 1058 /* Caller must hold page table lock. */ 1059 static void set_huge_zero_folio(pgtable_t pgtable, struct mm_struct *mm, 1060 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 1061 struct folio *zero_folio) 1062 { 1063 pmd_t entry; 1064 if (!pmd_none(*pmd)) 1065 return; 1066 entry = mk_pmd(&zero_folio->page, vma->vm_page_prot); 1067 entry = pmd_mkhuge(entry); 1068 pgtable_trans_huge_deposit(mm, pmd, pgtable); 1069 set_pmd_at(mm, haddr, pmd, entry); 1070 mm_inc_nr_ptes(mm); 1071 } 1072 1073 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 1074 { 1075 struct vm_area_struct *vma = vmf->vma; 1076 gfp_t gfp; 1077 struct folio *folio; 1078 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1079 vm_fault_t ret; 1080 1081 if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER)) 1082 return VM_FAULT_FALLBACK; 1083 ret = vmf_anon_prepare(vmf); 1084 if (ret) 1085 return ret; 1086 khugepaged_enter_vma(vma, vma->vm_flags); 1087 1088 if (!(vmf->flags & FAULT_FLAG_WRITE) && 1089 !mm_forbids_zeropage(vma->vm_mm) && 1090 transparent_hugepage_use_zero_page()) { 1091 pgtable_t pgtable; 1092 struct folio *zero_folio; 1093 vm_fault_t ret; 1094 1095 pgtable = pte_alloc_one(vma->vm_mm); 1096 if (unlikely(!pgtable)) 1097 return VM_FAULT_OOM; 1098 zero_folio = mm_get_huge_zero_folio(vma->vm_mm); 1099 if (unlikely(!zero_folio)) { 1100 pte_free(vma->vm_mm, pgtable); 1101 count_vm_event(THP_FAULT_FALLBACK); 1102 return VM_FAULT_FALLBACK; 1103 } 1104 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1105 ret = 0; 1106 if (pmd_none(*vmf->pmd)) { 1107 ret = check_stable_address_space(vma->vm_mm); 1108 if (ret) { 1109 spin_unlock(vmf->ptl); 1110 pte_free(vma->vm_mm, pgtable); 1111 } else if (userfaultfd_missing(vma)) { 1112 spin_unlock(vmf->ptl); 1113 pte_free(vma->vm_mm, pgtable); 1114 ret = handle_userfault(vmf, VM_UFFD_MISSING); 1115 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 1116 } else { 1117 set_huge_zero_folio(pgtable, vma->vm_mm, vma, 1118 haddr, vmf->pmd, zero_folio); 1119 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1120 spin_unlock(vmf->ptl); 1121 } 1122 } else { 1123 spin_unlock(vmf->ptl); 1124 pte_free(vma->vm_mm, pgtable); 1125 } 1126 return ret; 1127 } 1128 gfp = vma_thp_gfp_mask(vma); 1129 folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true); 1130 if (unlikely(!folio)) { 1131 count_vm_event(THP_FAULT_FALLBACK); 1132 count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK); 1133 return VM_FAULT_FALLBACK; 1134 } 1135 return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp); 1136 } 1137 1138 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 1139 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 1140 pgtable_t pgtable) 1141 { 1142 struct mm_struct *mm = vma->vm_mm; 1143 pmd_t entry; 1144 spinlock_t *ptl; 1145 1146 ptl = pmd_lock(mm, pmd); 1147 if (!pmd_none(*pmd)) { 1148 if (write) { 1149 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 1150 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 1151 goto out_unlock; 1152 } 1153 entry = pmd_mkyoung(*pmd); 1154 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1155 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 1156 update_mmu_cache_pmd(vma, addr, pmd); 1157 } 1158 1159 goto out_unlock; 1160 } 1161 1162 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 1163 if (pfn_t_devmap(pfn)) 1164 entry = pmd_mkdevmap(entry); 1165 if (write) { 1166 entry = pmd_mkyoung(pmd_mkdirty(entry)); 1167 entry = maybe_pmd_mkwrite(entry, vma); 1168 } 1169 1170 if (pgtable) { 1171 pgtable_trans_huge_deposit(mm, pmd, pgtable); 1172 mm_inc_nr_ptes(mm); 1173 pgtable = NULL; 1174 } 1175 1176 set_pmd_at(mm, addr, pmd, entry); 1177 update_mmu_cache_pmd(vma, addr, pmd); 1178 1179 out_unlock: 1180 spin_unlock(ptl); 1181 if (pgtable) 1182 pte_free(mm, pgtable); 1183 } 1184 1185 /** 1186 * vmf_insert_pfn_pmd - insert a pmd size pfn 1187 * @vmf: Structure describing the fault 1188 * @pfn: pfn to insert 1189 * @write: whether it's a write fault 1190 * 1191 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info. 1192 * 1193 * Return: vm_fault_t value. 1194 */ 1195 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) 1196 { 1197 unsigned long addr = vmf->address & PMD_MASK; 1198 struct vm_area_struct *vma = vmf->vma; 1199 pgprot_t pgprot = vma->vm_page_prot; 1200 pgtable_t pgtable = NULL; 1201 1202 /* 1203 * If we had pmd_special, we could avoid all these restrictions, 1204 * but we need to be consistent with PTEs and architectures that 1205 * can't support a 'special' bit. 1206 */ 1207 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 1208 !pfn_t_devmap(pfn)); 1209 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1210 (VM_PFNMAP|VM_MIXEDMAP)); 1211 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1212 1213 if (addr < vma->vm_start || addr >= vma->vm_end) 1214 return VM_FAULT_SIGBUS; 1215 1216 if (arch_needs_pgtable_deposit()) { 1217 pgtable = pte_alloc_one(vma->vm_mm); 1218 if (!pgtable) 1219 return VM_FAULT_OOM; 1220 } 1221 1222 track_pfn_insert(vma, &pgprot, pfn); 1223 1224 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 1225 return VM_FAULT_NOPAGE; 1226 } 1227 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); 1228 1229 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1230 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 1231 { 1232 if (likely(vma->vm_flags & VM_WRITE)) 1233 pud = pud_mkwrite(pud); 1234 return pud; 1235 } 1236 1237 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 1238 pud_t *pud, pfn_t pfn, bool write) 1239 { 1240 struct mm_struct *mm = vma->vm_mm; 1241 pgprot_t prot = vma->vm_page_prot; 1242 pud_t entry; 1243 spinlock_t *ptl; 1244 1245 ptl = pud_lock(mm, pud); 1246 if (!pud_none(*pud)) { 1247 if (write) { 1248 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 1249 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 1250 goto out_unlock; 1251 } 1252 entry = pud_mkyoung(*pud); 1253 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 1254 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 1255 update_mmu_cache_pud(vma, addr, pud); 1256 } 1257 goto out_unlock; 1258 } 1259 1260 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 1261 if (pfn_t_devmap(pfn)) 1262 entry = pud_mkdevmap(entry); 1263 if (write) { 1264 entry = pud_mkyoung(pud_mkdirty(entry)); 1265 entry = maybe_pud_mkwrite(entry, vma); 1266 } 1267 set_pud_at(mm, addr, pud, entry); 1268 update_mmu_cache_pud(vma, addr, pud); 1269 1270 out_unlock: 1271 spin_unlock(ptl); 1272 } 1273 1274 /** 1275 * vmf_insert_pfn_pud - insert a pud size pfn 1276 * @vmf: Structure describing the fault 1277 * @pfn: pfn to insert 1278 * @write: whether it's a write fault 1279 * 1280 * Insert a pud size pfn. See vmf_insert_pfn() for additional info. 1281 * 1282 * Return: vm_fault_t value. 1283 */ 1284 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) 1285 { 1286 unsigned long addr = vmf->address & PUD_MASK; 1287 struct vm_area_struct *vma = vmf->vma; 1288 pgprot_t pgprot = vma->vm_page_prot; 1289 1290 /* 1291 * If we had pud_special, we could avoid all these restrictions, 1292 * but we need to be consistent with PTEs and architectures that 1293 * can't support a 'special' bit. 1294 */ 1295 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 1296 !pfn_t_devmap(pfn)); 1297 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1298 (VM_PFNMAP|VM_MIXEDMAP)); 1299 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1300 1301 if (addr < vma->vm_start || addr >= vma->vm_end) 1302 return VM_FAULT_SIGBUS; 1303 1304 track_pfn_insert(vma, &pgprot, pfn); 1305 1306 insert_pfn_pud(vma, addr, vmf->pud, pfn, write); 1307 return VM_FAULT_NOPAGE; 1308 } 1309 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); 1310 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1311 1312 void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 1313 pmd_t *pmd, bool write) 1314 { 1315 pmd_t _pmd; 1316 1317 _pmd = pmd_mkyoung(*pmd); 1318 if (write) 1319 _pmd = pmd_mkdirty(_pmd); 1320 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 1321 pmd, _pmd, write)) 1322 update_mmu_cache_pmd(vma, addr, pmd); 1323 } 1324 1325 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 1326 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 1327 { 1328 unsigned long pfn = pmd_pfn(*pmd); 1329 struct mm_struct *mm = vma->vm_mm; 1330 struct page *page; 1331 int ret; 1332 1333 assert_spin_locked(pmd_lockptr(mm, pmd)); 1334 1335 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 1336 return NULL; 1337 1338 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 1339 /* pass */; 1340 else 1341 return NULL; 1342 1343 if (flags & FOLL_TOUCH) 1344 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1345 1346 /* 1347 * device mapped pages can only be returned if the 1348 * caller will manage the page reference count. 1349 */ 1350 if (!(flags & (FOLL_GET | FOLL_PIN))) 1351 return ERR_PTR(-EEXIST); 1352 1353 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 1354 *pgmap = get_dev_pagemap(pfn, *pgmap); 1355 if (!*pgmap) 1356 return ERR_PTR(-EFAULT); 1357 page = pfn_to_page(pfn); 1358 ret = try_grab_folio(page_folio(page), 1, flags); 1359 if (ret) 1360 page = ERR_PTR(ret); 1361 1362 return page; 1363 } 1364 1365 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1366 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1367 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) 1368 { 1369 spinlock_t *dst_ptl, *src_ptl; 1370 struct page *src_page; 1371 struct folio *src_folio; 1372 pmd_t pmd; 1373 pgtable_t pgtable = NULL; 1374 int ret = -ENOMEM; 1375 1376 /* Skip if can be re-fill on fault */ 1377 if (!vma_is_anonymous(dst_vma)) 1378 return 0; 1379 1380 pgtable = pte_alloc_one(dst_mm); 1381 if (unlikely(!pgtable)) 1382 goto out; 1383 1384 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1385 src_ptl = pmd_lockptr(src_mm, src_pmd); 1386 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1387 1388 ret = -EAGAIN; 1389 pmd = *src_pmd; 1390 1391 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1392 if (unlikely(is_swap_pmd(pmd))) { 1393 swp_entry_t entry = pmd_to_swp_entry(pmd); 1394 1395 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1396 if (!is_readable_migration_entry(entry)) { 1397 entry = make_readable_migration_entry( 1398 swp_offset(entry)); 1399 pmd = swp_entry_to_pmd(entry); 1400 if (pmd_swp_soft_dirty(*src_pmd)) 1401 pmd = pmd_swp_mksoft_dirty(pmd); 1402 if (pmd_swp_uffd_wp(*src_pmd)) 1403 pmd = pmd_swp_mkuffd_wp(pmd); 1404 set_pmd_at(src_mm, addr, src_pmd, pmd); 1405 } 1406 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1407 mm_inc_nr_ptes(dst_mm); 1408 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1409 if (!userfaultfd_wp(dst_vma)) 1410 pmd = pmd_swp_clear_uffd_wp(pmd); 1411 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1412 ret = 0; 1413 goto out_unlock; 1414 } 1415 #endif 1416 1417 if (unlikely(!pmd_trans_huge(pmd))) { 1418 pte_free(dst_mm, pgtable); 1419 goto out_unlock; 1420 } 1421 /* 1422 * When page table lock is held, the huge zero pmd should not be 1423 * under splitting since we don't split the page itself, only pmd to 1424 * a page table. 1425 */ 1426 if (is_huge_zero_pmd(pmd)) { 1427 /* 1428 * mm_get_huge_zero_folio() will never allocate a new 1429 * folio here, since we already have a zero page to 1430 * copy. It just takes a reference. 1431 */ 1432 mm_get_huge_zero_folio(dst_mm); 1433 goto out_zero_page; 1434 } 1435 1436 src_page = pmd_page(pmd); 1437 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1438 src_folio = page_folio(src_page); 1439 1440 folio_get(src_folio); 1441 if (unlikely(folio_try_dup_anon_rmap_pmd(src_folio, src_page, src_vma))) { 1442 /* Page maybe pinned: split and retry the fault on PTEs. */ 1443 folio_put(src_folio); 1444 pte_free(dst_mm, pgtable); 1445 spin_unlock(src_ptl); 1446 spin_unlock(dst_ptl); 1447 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); 1448 return -EAGAIN; 1449 } 1450 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1451 out_zero_page: 1452 mm_inc_nr_ptes(dst_mm); 1453 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1454 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1455 if (!userfaultfd_wp(dst_vma)) 1456 pmd = pmd_clear_uffd_wp(pmd); 1457 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1458 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1459 1460 ret = 0; 1461 out_unlock: 1462 spin_unlock(src_ptl); 1463 spin_unlock(dst_ptl); 1464 out: 1465 return ret; 1466 } 1467 1468 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1469 void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1470 pud_t *pud, bool write) 1471 { 1472 pud_t _pud; 1473 1474 _pud = pud_mkyoung(*pud); 1475 if (write) 1476 _pud = pud_mkdirty(_pud); 1477 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1478 pud, _pud, write)) 1479 update_mmu_cache_pud(vma, addr, pud); 1480 } 1481 1482 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1483 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1484 struct vm_area_struct *vma) 1485 { 1486 spinlock_t *dst_ptl, *src_ptl; 1487 pud_t pud; 1488 int ret; 1489 1490 dst_ptl = pud_lock(dst_mm, dst_pud); 1491 src_ptl = pud_lockptr(src_mm, src_pud); 1492 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1493 1494 ret = -EAGAIN; 1495 pud = *src_pud; 1496 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1497 goto out_unlock; 1498 1499 /* 1500 * When page table lock is held, the huge zero pud should not be 1501 * under splitting since we don't split the page itself, only pud to 1502 * a page table. 1503 */ 1504 if (is_huge_zero_pud(pud)) { 1505 /* No huge zero pud yet */ 1506 } 1507 1508 /* 1509 * TODO: once we support anonymous pages, use 1510 * folio_try_dup_anon_rmap_*() and split if duplicating fails. 1511 */ 1512 pudp_set_wrprotect(src_mm, addr, src_pud); 1513 pud = pud_mkold(pud_wrprotect(pud)); 1514 set_pud_at(dst_mm, addr, dst_pud, pud); 1515 1516 ret = 0; 1517 out_unlock: 1518 spin_unlock(src_ptl); 1519 spin_unlock(dst_ptl); 1520 return ret; 1521 } 1522 1523 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1524 { 1525 bool write = vmf->flags & FAULT_FLAG_WRITE; 1526 1527 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1528 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1529 goto unlock; 1530 1531 touch_pud(vmf->vma, vmf->address, vmf->pud, write); 1532 unlock: 1533 spin_unlock(vmf->ptl); 1534 } 1535 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1536 1537 void huge_pmd_set_accessed(struct vm_fault *vmf) 1538 { 1539 bool write = vmf->flags & FAULT_FLAG_WRITE; 1540 1541 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1542 if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) 1543 goto unlock; 1544 1545 touch_pmd(vmf->vma, vmf->address, vmf->pmd, write); 1546 1547 unlock: 1548 spin_unlock(vmf->ptl); 1549 } 1550 1551 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) 1552 { 1553 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; 1554 struct vm_area_struct *vma = vmf->vma; 1555 struct folio *folio; 1556 struct page *page; 1557 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1558 pmd_t orig_pmd = vmf->orig_pmd; 1559 1560 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1561 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1562 1563 if (is_huge_zero_pmd(orig_pmd)) 1564 goto fallback; 1565 1566 spin_lock(vmf->ptl); 1567 1568 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1569 spin_unlock(vmf->ptl); 1570 return 0; 1571 } 1572 1573 page = pmd_page(orig_pmd); 1574 folio = page_folio(page); 1575 VM_BUG_ON_PAGE(!PageHead(page), page); 1576 1577 /* Early check when only holding the PT lock. */ 1578 if (PageAnonExclusive(page)) 1579 goto reuse; 1580 1581 if (!folio_trylock(folio)) { 1582 folio_get(folio); 1583 spin_unlock(vmf->ptl); 1584 folio_lock(folio); 1585 spin_lock(vmf->ptl); 1586 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1587 spin_unlock(vmf->ptl); 1588 folio_unlock(folio); 1589 folio_put(folio); 1590 return 0; 1591 } 1592 folio_put(folio); 1593 } 1594 1595 /* Recheck after temporarily dropping the PT lock. */ 1596 if (PageAnonExclusive(page)) { 1597 folio_unlock(folio); 1598 goto reuse; 1599 } 1600 1601 /* 1602 * See do_wp_page(): we can only reuse the folio exclusively if 1603 * there are no additional references. Note that we always drain 1604 * the LRU cache immediately after adding a THP. 1605 */ 1606 if (folio_ref_count(folio) > 1607 1 + folio_test_swapcache(folio) * folio_nr_pages(folio)) 1608 goto unlock_fallback; 1609 if (folio_test_swapcache(folio)) 1610 folio_free_swap(folio); 1611 if (folio_ref_count(folio) == 1) { 1612 pmd_t entry; 1613 1614 folio_move_anon_rmap(folio, vma); 1615 SetPageAnonExclusive(page); 1616 folio_unlock(folio); 1617 reuse: 1618 if (unlikely(unshare)) { 1619 spin_unlock(vmf->ptl); 1620 return 0; 1621 } 1622 entry = pmd_mkyoung(orig_pmd); 1623 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1624 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1625 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1626 spin_unlock(vmf->ptl); 1627 return 0; 1628 } 1629 1630 unlock_fallback: 1631 folio_unlock(folio); 1632 spin_unlock(vmf->ptl); 1633 fallback: 1634 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1635 return VM_FAULT_FALLBACK; 1636 } 1637 1638 static inline bool can_change_pmd_writable(struct vm_area_struct *vma, 1639 unsigned long addr, pmd_t pmd) 1640 { 1641 struct page *page; 1642 1643 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) 1644 return false; 1645 1646 /* Don't touch entries that are not even readable (NUMA hinting). */ 1647 if (pmd_protnone(pmd)) 1648 return false; 1649 1650 /* Do we need write faults for softdirty tracking? */ 1651 if (pmd_needs_soft_dirty_wp(vma, pmd)) 1652 return false; 1653 1654 /* Do we need write faults for uffd-wp tracking? */ 1655 if (userfaultfd_huge_pmd_wp(vma, pmd)) 1656 return false; 1657 1658 if (!(vma->vm_flags & VM_SHARED)) { 1659 /* See can_change_pte_writable(). */ 1660 page = vm_normal_page_pmd(vma, addr, pmd); 1661 return page && PageAnon(page) && PageAnonExclusive(page); 1662 } 1663 1664 /* See can_change_pte_writable(). */ 1665 return pmd_dirty(pmd); 1666 } 1667 1668 /* NUMA hinting page fault entry point for trans huge pmds */ 1669 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) 1670 { 1671 struct vm_area_struct *vma = vmf->vma; 1672 struct folio *folio; 1673 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1674 int nid = NUMA_NO_NODE; 1675 int target_nid, last_cpupid; 1676 pmd_t pmd, old_pmd; 1677 bool writable = false; 1678 int flags = 0; 1679 1680 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1681 old_pmd = pmdp_get(vmf->pmd); 1682 1683 if (unlikely(!pmd_same(old_pmd, vmf->orig_pmd))) { 1684 spin_unlock(vmf->ptl); 1685 return 0; 1686 } 1687 1688 pmd = pmd_modify(old_pmd, vma->vm_page_prot); 1689 1690 /* 1691 * Detect now whether the PMD could be writable; this information 1692 * is only valid while holding the PT lock. 1693 */ 1694 writable = pmd_write(pmd); 1695 if (!writable && vma_wants_manual_pte_write_upgrade(vma) && 1696 can_change_pmd_writable(vma, vmf->address, pmd)) 1697 writable = true; 1698 1699 folio = vm_normal_folio_pmd(vma, haddr, pmd); 1700 if (!folio) 1701 goto out_map; 1702 1703 nid = folio_nid(folio); 1704 1705 target_nid = numa_migrate_check(folio, vmf, haddr, &flags, writable, 1706 &last_cpupid); 1707 if (target_nid == NUMA_NO_NODE) 1708 goto out_map; 1709 if (migrate_misplaced_folio_prepare(folio, vma, target_nid)) { 1710 flags |= TNF_MIGRATE_FAIL; 1711 goto out_map; 1712 } 1713 /* The folio is isolated and isolation code holds a folio reference. */ 1714 spin_unlock(vmf->ptl); 1715 writable = false; 1716 1717 if (!migrate_misplaced_folio(folio, vma, target_nid)) { 1718 flags |= TNF_MIGRATED; 1719 nid = target_nid; 1720 task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags); 1721 return 0; 1722 } 1723 1724 flags |= TNF_MIGRATE_FAIL; 1725 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1726 if (unlikely(!pmd_same(pmdp_get(vmf->pmd), vmf->orig_pmd))) { 1727 spin_unlock(vmf->ptl); 1728 return 0; 1729 } 1730 out_map: 1731 /* Restore the PMD */ 1732 pmd = pmd_modify(pmdp_get(vmf->pmd), vma->vm_page_prot); 1733 pmd = pmd_mkyoung(pmd); 1734 if (writable) 1735 pmd = pmd_mkwrite(pmd, vma); 1736 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1737 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1738 spin_unlock(vmf->ptl); 1739 1740 if (nid != NUMA_NO_NODE) 1741 task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags); 1742 return 0; 1743 } 1744 1745 /* 1746 * Return true if we do MADV_FREE successfully on entire pmd page. 1747 * Otherwise, return false. 1748 */ 1749 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1750 pmd_t *pmd, unsigned long addr, unsigned long next) 1751 { 1752 spinlock_t *ptl; 1753 pmd_t orig_pmd; 1754 struct folio *folio; 1755 struct mm_struct *mm = tlb->mm; 1756 bool ret = false; 1757 1758 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1759 1760 ptl = pmd_trans_huge_lock(pmd, vma); 1761 if (!ptl) 1762 goto out_unlocked; 1763 1764 orig_pmd = *pmd; 1765 if (is_huge_zero_pmd(orig_pmd)) 1766 goto out; 1767 1768 if (unlikely(!pmd_present(orig_pmd))) { 1769 VM_BUG_ON(thp_migration_supported() && 1770 !is_pmd_migration_entry(orig_pmd)); 1771 goto out; 1772 } 1773 1774 folio = pmd_folio(orig_pmd); 1775 /* 1776 * If other processes are mapping this folio, we couldn't discard 1777 * the folio unless they all do MADV_FREE so let's skip the folio. 1778 */ 1779 if (folio_likely_mapped_shared(folio)) 1780 goto out; 1781 1782 if (!folio_trylock(folio)) 1783 goto out; 1784 1785 /* 1786 * If user want to discard part-pages of THP, split it so MADV_FREE 1787 * will deactivate only them. 1788 */ 1789 if (next - addr != HPAGE_PMD_SIZE) { 1790 folio_get(folio); 1791 spin_unlock(ptl); 1792 split_folio(folio); 1793 folio_unlock(folio); 1794 folio_put(folio); 1795 goto out_unlocked; 1796 } 1797 1798 if (folio_test_dirty(folio)) 1799 folio_clear_dirty(folio); 1800 folio_unlock(folio); 1801 1802 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1803 pmdp_invalidate(vma, addr, pmd); 1804 orig_pmd = pmd_mkold(orig_pmd); 1805 orig_pmd = pmd_mkclean(orig_pmd); 1806 1807 set_pmd_at(mm, addr, pmd, orig_pmd); 1808 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1809 } 1810 1811 folio_mark_lazyfree(folio); 1812 ret = true; 1813 out: 1814 spin_unlock(ptl); 1815 out_unlocked: 1816 return ret; 1817 } 1818 1819 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1820 { 1821 pgtable_t pgtable; 1822 1823 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1824 pte_free(mm, pgtable); 1825 mm_dec_nr_ptes(mm); 1826 } 1827 1828 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1829 pmd_t *pmd, unsigned long addr) 1830 { 1831 pmd_t orig_pmd; 1832 spinlock_t *ptl; 1833 1834 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1835 1836 ptl = __pmd_trans_huge_lock(pmd, vma); 1837 if (!ptl) 1838 return 0; 1839 /* 1840 * For architectures like ppc64 we look at deposited pgtable 1841 * when calling pmdp_huge_get_and_clear. So do the 1842 * pgtable_trans_huge_withdraw after finishing pmdp related 1843 * operations. 1844 */ 1845 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1846 tlb->fullmm); 1847 arch_check_zapped_pmd(vma, orig_pmd); 1848 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1849 if (vma_is_special_huge(vma)) { 1850 if (arch_needs_pgtable_deposit()) 1851 zap_deposited_table(tlb->mm, pmd); 1852 spin_unlock(ptl); 1853 } else if (is_huge_zero_pmd(orig_pmd)) { 1854 zap_deposited_table(tlb->mm, pmd); 1855 spin_unlock(ptl); 1856 } else { 1857 struct folio *folio = NULL; 1858 int flush_needed = 1; 1859 1860 if (pmd_present(orig_pmd)) { 1861 struct page *page = pmd_page(orig_pmd); 1862 1863 folio = page_folio(page); 1864 folio_remove_rmap_pmd(folio, page, vma); 1865 WARN_ON_ONCE(folio_mapcount(folio) < 0); 1866 VM_BUG_ON_PAGE(!PageHead(page), page); 1867 } else if (thp_migration_supported()) { 1868 swp_entry_t entry; 1869 1870 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1871 entry = pmd_to_swp_entry(orig_pmd); 1872 folio = pfn_swap_entry_folio(entry); 1873 flush_needed = 0; 1874 } else 1875 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1876 1877 if (folio_test_anon(folio)) { 1878 zap_deposited_table(tlb->mm, pmd); 1879 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1880 } else { 1881 if (arch_needs_pgtable_deposit()) 1882 zap_deposited_table(tlb->mm, pmd); 1883 add_mm_counter(tlb->mm, mm_counter_file(folio), 1884 -HPAGE_PMD_NR); 1885 } 1886 1887 spin_unlock(ptl); 1888 if (flush_needed) 1889 tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE); 1890 } 1891 return 1; 1892 } 1893 1894 #ifndef pmd_move_must_withdraw 1895 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1896 spinlock_t *old_pmd_ptl, 1897 struct vm_area_struct *vma) 1898 { 1899 /* 1900 * With split pmd lock we also need to move preallocated 1901 * PTE page table if new_pmd is on different PMD page table. 1902 * 1903 * We also don't deposit and withdraw tables for file pages. 1904 */ 1905 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1906 } 1907 #endif 1908 1909 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1910 { 1911 #ifdef CONFIG_MEM_SOFT_DIRTY 1912 if (unlikely(is_pmd_migration_entry(pmd))) 1913 pmd = pmd_swp_mksoft_dirty(pmd); 1914 else if (pmd_present(pmd)) 1915 pmd = pmd_mksoft_dirty(pmd); 1916 #endif 1917 return pmd; 1918 } 1919 1920 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1921 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1922 { 1923 spinlock_t *old_ptl, *new_ptl; 1924 pmd_t pmd; 1925 struct mm_struct *mm = vma->vm_mm; 1926 bool force_flush = false; 1927 1928 /* 1929 * The destination pmd shouldn't be established, free_pgtables() 1930 * should have released it; but move_page_tables() might have already 1931 * inserted a page table, if racing against shmem/file collapse. 1932 */ 1933 if (!pmd_none(*new_pmd)) { 1934 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1935 return false; 1936 } 1937 1938 /* 1939 * We don't have to worry about the ordering of src and dst 1940 * ptlocks because exclusive mmap_lock prevents deadlock. 1941 */ 1942 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1943 if (old_ptl) { 1944 new_ptl = pmd_lockptr(mm, new_pmd); 1945 if (new_ptl != old_ptl) 1946 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1947 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1948 if (pmd_present(pmd)) 1949 force_flush = true; 1950 VM_BUG_ON(!pmd_none(*new_pmd)); 1951 1952 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1953 pgtable_t pgtable; 1954 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1955 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1956 } 1957 pmd = move_soft_dirty_pmd(pmd); 1958 set_pmd_at(mm, new_addr, new_pmd, pmd); 1959 if (force_flush) 1960 flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1961 if (new_ptl != old_ptl) 1962 spin_unlock(new_ptl); 1963 spin_unlock(old_ptl); 1964 return true; 1965 } 1966 return false; 1967 } 1968 1969 /* 1970 * Returns 1971 * - 0 if PMD could not be locked 1972 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary 1973 * or if prot_numa but THP migration is not supported 1974 * - HPAGE_PMD_NR if protections changed and TLB flush necessary 1975 */ 1976 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1977 pmd_t *pmd, unsigned long addr, pgprot_t newprot, 1978 unsigned long cp_flags) 1979 { 1980 struct mm_struct *mm = vma->vm_mm; 1981 spinlock_t *ptl; 1982 pmd_t oldpmd, entry; 1983 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1984 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1985 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1986 int ret = 1; 1987 1988 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1989 1990 if (prot_numa && !thp_migration_supported()) 1991 return 1; 1992 1993 ptl = __pmd_trans_huge_lock(pmd, vma); 1994 if (!ptl) 1995 return 0; 1996 1997 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1998 if (is_swap_pmd(*pmd)) { 1999 swp_entry_t entry = pmd_to_swp_entry(*pmd); 2000 struct folio *folio = pfn_swap_entry_folio(entry); 2001 pmd_t newpmd; 2002 2003 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 2004 if (is_writable_migration_entry(entry)) { 2005 /* 2006 * A protection check is difficult so 2007 * just be safe and disable write 2008 */ 2009 if (folio_test_anon(folio)) 2010 entry = make_readable_exclusive_migration_entry(swp_offset(entry)); 2011 else 2012 entry = make_readable_migration_entry(swp_offset(entry)); 2013 newpmd = swp_entry_to_pmd(entry); 2014 if (pmd_swp_soft_dirty(*pmd)) 2015 newpmd = pmd_swp_mksoft_dirty(newpmd); 2016 } else { 2017 newpmd = *pmd; 2018 } 2019 2020 if (uffd_wp) 2021 newpmd = pmd_swp_mkuffd_wp(newpmd); 2022 else if (uffd_wp_resolve) 2023 newpmd = pmd_swp_clear_uffd_wp(newpmd); 2024 if (!pmd_same(*pmd, newpmd)) 2025 set_pmd_at(mm, addr, pmd, newpmd); 2026 goto unlock; 2027 } 2028 #endif 2029 2030 if (prot_numa) { 2031 struct folio *folio; 2032 bool toptier; 2033 /* 2034 * Avoid trapping faults against the zero page. The read-only 2035 * data is likely to be read-cached on the local CPU and 2036 * local/remote hits to the zero page are not interesting. 2037 */ 2038 if (is_huge_zero_pmd(*pmd)) 2039 goto unlock; 2040 2041 if (pmd_protnone(*pmd)) 2042 goto unlock; 2043 2044 folio = pmd_folio(*pmd); 2045 toptier = node_is_toptier(folio_nid(folio)); 2046 /* 2047 * Skip scanning top tier node if normal numa 2048 * balancing is disabled 2049 */ 2050 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 2051 toptier) 2052 goto unlock; 2053 2054 if (folio_use_access_time(folio)) 2055 folio_xchg_access_time(folio, 2056 jiffies_to_msecs(jiffies)); 2057 } 2058 /* 2059 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 2060 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 2061 * which is also under mmap_read_lock(mm): 2062 * 2063 * CPU0: CPU1: 2064 * change_huge_pmd(prot_numa=1) 2065 * pmdp_huge_get_and_clear_notify() 2066 * madvise_dontneed() 2067 * zap_pmd_range() 2068 * pmd_trans_huge(*pmd) == 0 (without ptl) 2069 * // skip the pmd 2070 * set_pmd_at(); 2071 * // pmd is re-established 2072 * 2073 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 2074 * which may break userspace. 2075 * 2076 * pmdp_invalidate_ad() is required to make sure we don't miss 2077 * dirty/young flags set by hardware. 2078 */ 2079 oldpmd = pmdp_invalidate_ad(vma, addr, pmd); 2080 2081 entry = pmd_modify(oldpmd, newprot); 2082 if (uffd_wp) 2083 entry = pmd_mkuffd_wp(entry); 2084 else if (uffd_wp_resolve) 2085 /* 2086 * Leave the write bit to be handled by PF interrupt 2087 * handler, then things like COW could be properly 2088 * handled. 2089 */ 2090 entry = pmd_clear_uffd_wp(entry); 2091 2092 /* See change_pte_range(). */ 2093 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) && 2094 can_change_pmd_writable(vma, addr, entry)) 2095 entry = pmd_mkwrite(entry, vma); 2096 2097 ret = HPAGE_PMD_NR; 2098 set_pmd_at(mm, addr, pmd, entry); 2099 2100 if (huge_pmd_needs_flush(oldpmd, entry)) 2101 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); 2102 unlock: 2103 spin_unlock(ptl); 2104 return ret; 2105 } 2106 2107 #ifdef CONFIG_USERFAULTFD 2108 /* 2109 * The PT lock for src_pmd and dst_vma/src_vma (for reading) are locked by 2110 * the caller, but it must return after releasing the page_table_lock. 2111 * Just move the page from src_pmd to dst_pmd if possible. 2112 * Return zero if succeeded in moving the page, -EAGAIN if it needs to be 2113 * repeated by the caller, or other errors in case of failure. 2114 */ 2115 int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval, 2116 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, 2117 unsigned long dst_addr, unsigned long src_addr) 2118 { 2119 pmd_t _dst_pmd, src_pmdval; 2120 struct page *src_page; 2121 struct folio *src_folio; 2122 struct anon_vma *src_anon_vma; 2123 spinlock_t *src_ptl, *dst_ptl; 2124 pgtable_t src_pgtable; 2125 struct mmu_notifier_range range; 2126 int err = 0; 2127 2128 src_pmdval = *src_pmd; 2129 src_ptl = pmd_lockptr(mm, src_pmd); 2130 2131 lockdep_assert_held(src_ptl); 2132 vma_assert_locked(src_vma); 2133 vma_assert_locked(dst_vma); 2134 2135 /* Sanity checks before the operation */ 2136 if (WARN_ON_ONCE(!pmd_none(dst_pmdval)) || WARN_ON_ONCE(src_addr & ~HPAGE_PMD_MASK) || 2137 WARN_ON_ONCE(dst_addr & ~HPAGE_PMD_MASK)) { 2138 spin_unlock(src_ptl); 2139 return -EINVAL; 2140 } 2141 2142 if (!pmd_trans_huge(src_pmdval)) { 2143 spin_unlock(src_ptl); 2144 if (is_pmd_migration_entry(src_pmdval)) { 2145 pmd_migration_entry_wait(mm, &src_pmdval); 2146 return -EAGAIN; 2147 } 2148 return -ENOENT; 2149 } 2150 2151 src_page = pmd_page(src_pmdval); 2152 2153 if (!is_huge_zero_pmd(src_pmdval)) { 2154 if (unlikely(!PageAnonExclusive(src_page))) { 2155 spin_unlock(src_ptl); 2156 return -EBUSY; 2157 } 2158 2159 src_folio = page_folio(src_page); 2160 folio_get(src_folio); 2161 } else 2162 src_folio = NULL; 2163 2164 spin_unlock(src_ptl); 2165 2166 flush_cache_range(src_vma, src_addr, src_addr + HPAGE_PMD_SIZE); 2167 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, src_addr, 2168 src_addr + HPAGE_PMD_SIZE); 2169 mmu_notifier_invalidate_range_start(&range); 2170 2171 if (src_folio) { 2172 folio_lock(src_folio); 2173 2174 /* 2175 * split_huge_page walks the anon_vma chain without the page 2176 * lock. Serialize against it with the anon_vma lock, the page 2177 * lock is not enough. 2178 */ 2179 src_anon_vma = folio_get_anon_vma(src_folio); 2180 if (!src_anon_vma) { 2181 err = -EAGAIN; 2182 goto unlock_folio; 2183 } 2184 anon_vma_lock_write(src_anon_vma); 2185 } else 2186 src_anon_vma = NULL; 2187 2188 dst_ptl = pmd_lockptr(mm, dst_pmd); 2189 double_pt_lock(src_ptl, dst_ptl); 2190 if (unlikely(!pmd_same(*src_pmd, src_pmdval) || 2191 !pmd_same(*dst_pmd, dst_pmdval))) { 2192 err = -EAGAIN; 2193 goto unlock_ptls; 2194 } 2195 if (src_folio) { 2196 if (folio_maybe_dma_pinned(src_folio) || 2197 !PageAnonExclusive(&src_folio->page)) { 2198 err = -EBUSY; 2199 goto unlock_ptls; 2200 } 2201 2202 if (WARN_ON_ONCE(!folio_test_head(src_folio)) || 2203 WARN_ON_ONCE(!folio_test_anon(src_folio))) { 2204 err = -EBUSY; 2205 goto unlock_ptls; 2206 } 2207 2208 src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); 2209 /* Folio got pinned from under us. Put it back and fail the move. */ 2210 if (folio_maybe_dma_pinned(src_folio)) { 2211 set_pmd_at(mm, src_addr, src_pmd, src_pmdval); 2212 err = -EBUSY; 2213 goto unlock_ptls; 2214 } 2215 2216 folio_move_anon_rmap(src_folio, dst_vma); 2217 src_folio->index = linear_page_index(dst_vma, dst_addr); 2218 2219 _dst_pmd = mk_huge_pmd(&src_folio->page, dst_vma->vm_page_prot); 2220 /* Follow mremap() behavior and treat the entry dirty after the move */ 2221 _dst_pmd = pmd_mkwrite(pmd_mkdirty(_dst_pmd), dst_vma); 2222 } else { 2223 src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); 2224 _dst_pmd = mk_huge_pmd(src_page, dst_vma->vm_page_prot); 2225 } 2226 set_pmd_at(mm, dst_addr, dst_pmd, _dst_pmd); 2227 2228 src_pgtable = pgtable_trans_huge_withdraw(mm, src_pmd); 2229 pgtable_trans_huge_deposit(mm, dst_pmd, src_pgtable); 2230 unlock_ptls: 2231 double_pt_unlock(src_ptl, dst_ptl); 2232 if (src_anon_vma) { 2233 anon_vma_unlock_write(src_anon_vma); 2234 put_anon_vma(src_anon_vma); 2235 } 2236 unlock_folio: 2237 /* unblock rmap walks */ 2238 if (src_folio) 2239 folio_unlock(src_folio); 2240 mmu_notifier_invalidate_range_end(&range); 2241 if (src_folio) 2242 folio_put(src_folio); 2243 return err; 2244 } 2245 #endif /* CONFIG_USERFAULTFD */ 2246 2247 /* 2248 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 2249 * 2250 * Note that if it returns page table lock pointer, this routine returns without 2251 * unlocking page table lock. So callers must unlock it. 2252 */ 2253 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 2254 { 2255 spinlock_t *ptl; 2256 ptl = pmd_lock(vma->vm_mm, pmd); 2257 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 2258 pmd_devmap(*pmd))) 2259 return ptl; 2260 spin_unlock(ptl); 2261 return NULL; 2262 } 2263 2264 /* 2265 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. 2266 * 2267 * Note that if it returns page table lock pointer, this routine returns without 2268 * unlocking page table lock. So callers must unlock it. 2269 */ 2270 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 2271 { 2272 spinlock_t *ptl; 2273 2274 ptl = pud_lock(vma->vm_mm, pud); 2275 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 2276 return ptl; 2277 spin_unlock(ptl); 2278 return NULL; 2279 } 2280 2281 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 2282 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 2283 pud_t *pud, unsigned long addr) 2284 { 2285 spinlock_t *ptl; 2286 2287 ptl = __pud_trans_huge_lock(pud, vma); 2288 if (!ptl) 2289 return 0; 2290 2291 pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm); 2292 tlb_remove_pud_tlb_entry(tlb, pud, addr); 2293 if (vma_is_special_huge(vma)) { 2294 spin_unlock(ptl); 2295 /* No zero page support yet */ 2296 } else { 2297 /* No support for anonymous PUD pages yet */ 2298 BUG(); 2299 } 2300 return 1; 2301 } 2302 2303 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 2304 unsigned long haddr) 2305 { 2306 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 2307 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2308 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 2309 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 2310 2311 count_vm_event(THP_SPLIT_PUD); 2312 2313 pudp_huge_clear_flush(vma, haddr, pud); 2314 } 2315 2316 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 2317 unsigned long address) 2318 { 2319 spinlock_t *ptl; 2320 struct mmu_notifier_range range; 2321 2322 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, 2323 address & HPAGE_PUD_MASK, 2324 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 2325 mmu_notifier_invalidate_range_start(&range); 2326 ptl = pud_lock(vma->vm_mm, pud); 2327 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 2328 goto out; 2329 __split_huge_pud_locked(vma, pud, range.start); 2330 2331 out: 2332 spin_unlock(ptl); 2333 mmu_notifier_invalidate_range_end(&range); 2334 } 2335 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 2336 2337 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2338 unsigned long haddr, pmd_t *pmd) 2339 { 2340 struct mm_struct *mm = vma->vm_mm; 2341 pgtable_t pgtable; 2342 pmd_t _pmd, old_pmd; 2343 unsigned long addr; 2344 pte_t *pte; 2345 int i; 2346 2347 /* 2348 * Leave pmd empty until pte is filled note that it is fine to delay 2349 * notification until mmu_notifier_invalidate_range_end() as we are 2350 * replacing a zero pmd write protected page with a zero pte write 2351 * protected page. 2352 * 2353 * See Documentation/mm/mmu_notifier.rst 2354 */ 2355 old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); 2356 2357 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2358 pmd_populate(mm, &_pmd, pgtable); 2359 2360 pte = pte_offset_map(&_pmd, haddr); 2361 VM_BUG_ON(!pte); 2362 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2363 pte_t entry; 2364 2365 entry = pfn_pte(my_zero_pfn(addr), vma->vm_page_prot); 2366 entry = pte_mkspecial(entry); 2367 if (pmd_uffd_wp(old_pmd)) 2368 entry = pte_mkuffd_wp(entry); 2369 VM_BUG_ON(!pte_none(ptep_get(pte))); 2370 set_pte_at(mm, addr, pte, entry); 2371 pte++; 2372 } 2373 pte_unmap(pte - 1); 2374 smp_wmb(); /* make pte visible before pmd */ 2375 pmd_populate(mm, pmd, pgtable); 2376 } 2377 2378 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2379 unsigned long haddr, bool freeze) 2380 { 2381 struct mm_struct *mm = vma->vm_mm; 2382 struct folio *folio; 2383 struct page *page; 2384 pgtable_t pgtable; 2385 pmd_t old_pmd, _pmd; 2386 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 2387 bool anon_exclusive = false, dirty = false; 2388 unsigned long addr; 2389 pte_t *pte; 2390 int i; 2391 2392 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2393 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2394 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2395 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2396 && !pmd_devmap(*pmd)); 2397 2398 count_vm_event(THP_SPLIT_PMD); 2399 2400 if (!vma_is_anonymous(vma)) { 2401 old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); 2402 /* 2403 * We are going to unmap this huge page. So 2404 * just go ahead and zap it 2405 */ 2406 if (arch_needs_pgtable_deposit()) 2407 zap_deposited_table(mm, pmd); 2408 if (vma_is_special_huge(vma)) 2409 return; 2410 if (unlikely(is_pmd_migration_entry(old_pmd))) { 2411 swp_entry_t entry; 2412 2413 entry = pmd_to_swp_entry(old_pmd); 2414 folio = pfn_swap_entry_folio(entry); 2415 } else { 2416 page = pmd_page(old_pmd); 2417 folio = page_folio(page); 2418 if (!folio_test_dirty(folio) && pmd_dirty(old_pmd)) 2419 folio_mark_dirty(folio); 2420 if (!folio_test_referenced(folio) && pmd_young(old_pmd)) 2421 folio_set_referenced(folio); 2422 folio_remove_rmap_pmd(folio, page, vma); 2423 folio_put(folio); 2424 } 2425 add_mm_counter(mm, mm_counter_file(folio), -HPAGE_PMD_NR); 2426 return; 2427 } 2428 2429 if (is_huge_zero_pmd(*pmd)) { 2430 /* 2431 * FIXME: Do we want to invalidate secondary mmu by calling 2432 * mmu_notifier_arch_invalidate_secondary_tlbs() see comments below 2433 * inside __split_huge_pmd() ? 2434 * 2435 * We are going from a zero huge page write protected to zero 2436 * small page also write protected so it does not seems useful 2437 * to invalidate secondary mmu at this time. 2438 */ 2439 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2440 } 2441 2442 pmd_migration = is_pmd_migration_entry(*pmd); 2443 if (unlikely(pmd_migration)) { 2444 swp_entry_t entry; 2445 2446 old_pmd = *pmd; 2447 entry = pmd_to_swp_entry(old_pmd); 2448 page = pfn_swap_entry_to_page(entry); 2449 write = is_writable_migration_entry(entry); 2450 if (PageAnon(page)) 2451 anon_exclusive = is_readable_exclusive_migration_entry(entry); 2452 young = is_migration_entry_young(entry); 2453 dirty = is_migration_entry_dirty(entry); 2454 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2455 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2456 } else { 2457 /* 2458 * Up to this point the pmd is present and huge and userland has 2459 * the whole access to the hugepage during the split (which 2460 * happens in place). If we overwrite the pmd with the not-huge 2461 * version pointing to the pte here (which of course we could if 2462 * all CPUs were bug free), userland could trigger a small page 2463 * size TLB miss on the small sized TLB while the hugepage TLB 2464 * entry is still established in the huge TLB. Some CPU doesn't 2465 * like that. See 2466 * http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2467 * 383 on page 105. Intel should be safe but is also warns that 2468 * it's only safe if the permission and cache attributes of the 2469 * two entries loaded in the two TLB is identical (which should 2470 * be the case here). But it is generally safer to never allow 2471 * small and huge TLB entries for the same virtual address to be 2472 * loaded simultaneously. So instead of doing "pmd_populate(); 2473 * flush_pmd_tlb_range();" we first mark the current pmd 2474 * notpresent (atomically because here the pmd_trans_huge must 2475 * remain set at all times on the pmd until the split is 2476 * complete for this pmd), then we flush the SMP TLB and finally 2477 * we write the non-huge version of the pmd entry with 2478 * pmd_populate. 2479 */ 2480 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2481 page = pmd_page(old_pmd); 2482 folio = page_folio(page); 2483 if (pmd_dirty(old_pmd)) { 2484 dirty = true; 2485 folio_set_dirty(folio); 2486 } 2487 write = pmd_write(old_pmd); 2488 young = pmd_young(old_pmd); 2489 soft_dirty = pmd_soft_dirty(old_pmd); 2490 uffd_wp = pmd_uffd_wp(old_pmd); 2491 2492 VM_WARN_ON_FOLIO(!folio_ref_count(folio), folio); 2493 VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); 2494 2495 /* 2496 * Without "freeze", we'll simply split the PMD, propagating the 2497 * PageAnonExclusive() flag for each PTE by setting it for 2498 * each subpage -- no need to (temporarily) clear. 2499 * 2500 * With "freeze" we want to replace mapped pages by 2501 * migration entries right away. This is only possible if we 2502 * managed to clear PageAnonExclusive() -- see 2503 * set_pmd_migration_entry(). 2504 * 2505 * In case we cannot clear PageAnonExclusive(), split the PMD 2506 * only and let try_to_migrate_one() fail later. 2507 * 2508 * See folio_try_share_anon_rmap_pmd(): invalidate PMD first. 2509 */ 2510 anon_exclusive = PageAnonExclusive(page); 2511 if (freeze && anon_exclusive && 2512 folio_try_share_anon_rmap_pmd(folio, page)) 2513 freeze = false; 2514 if (!freeze) { 2515 rmap_t rmap_flags = RMAP_NONE; 2516 2517 folio_ref_add(folio, HPAGE_PMD_NR - 1); 2518 if (anon_exclusive) 2519 rmap_flags |= RMAP_EXCLUSIVE; 2520 folio_add_anon_rmap_ptes(folio, page, HPAGE_PMD_NR, 2521 vma, haddr, rmap_flags); 2522 } 2523 } 2524 2525 /* 2526 * Withdraw the table only after we mark the pmd entry invalid. 2527 * This's critical for some architectures (Power). 2528 */ 2529 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2530 pmd_populate(mm, &_pmd, pgtable); 2531 2532 pte = pte_offset_map(&_pmd, haddr); 2533 VM_BUG_ON(!pte); 2534 2535 /* 2536 * Note that NUMA hinting access restrictions are not transferred to 2537 * avoid any possibility of altering permissions across VMAs. 2538 */ 2539 if (freeze || pmd_migration) { 2540 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2541 pte_t entry; 2542 swp_entry_t swp_entry; 2543 2544 if (write) 2545 swp_entry = make_writable_migration_entry( 2546 page_to_pfn(page + i)); 2547 else if (anon_exclusive) 2548 swp_entry = make_readable_exclusive_migration_entry( 2549 page_to_pfn(page + i)); 2550 else 2551 swp_entry = make_readable_migration_entry( 2552 page_to_pfn(page + i)); 2553 if (young) 2554 swp_entry = make_migration_entry_young(swp_entry); 2555 if (dirty) 2556 swp_entry = make_migration_entry_dirty(swp_entry); 2557 entry = swp_entry_to_pte(swp_entry); 2558 if (soft_dirty) 2559 entry = pte_swp_mksoft_dirty(entry); 2560 if (uffd_wp) 2561 entry = pte_swp_mkuffd_wp(entry); 2562 2563 VM_WARN_ON(!pte_none(ptep_get(pte + i))); 2564 set_pte_at(mm, addr, pte + i, entry); 2565 } 2566 } else { 2567 pte_t entry; 2568 2569 entry = mk_pte(page, READ_ONCE(vma->vm_page_prot)); 2570 if (write) 2571 entry = pte_mkwrite(entry, vma); 2572 if (!young) 2573 entry = pte_mkold(entry); 2574 /* NOTE: this may set soft-dirty too on some archs */ 2575 if (dirty) 2576 entry = pte_mkdirty(entry); 2577 if (soft_dirty) 2578 entry = pte_mksoft_dirty(entry); 2579 if (uffd_wp) 2580 entry = pte_mkuffd_wp(entry); 2581 2582 for (i = 0; i < HPAGE_PMD_NR; i++) 2583 VM_WARN_ON(!pte_none(ptep_get(pte + i))); 2584 2585 set_ptes(mm, haddr, pte, entry, HPAGE_PMD_NR); 2586 } 2587 pte_unmap(pte); 2588 2589 if (!pmd_migration) 2590 folio_remove_rmap_pmd(folio, page, vma); 2591 if (freeze) 2592 put_page(page); 2593 2594 smp_wmb(); /* make pte visible before pmd */ 2595 pmd_populate(mm, pmd, pgtable); 2596 } 2597 2598 void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long address, 2599 pmd_t *pmd, bool freeze, struct folio *folio) 2600 { 2601 VM_WARN_ON_ONCE(folio && !folio_test_pmd_mappable(folio)); 2602 VM_WARN_ON_ONCE(!IS_ALIGNED(address, HPAGE_PMD_SIZE)); 2603 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); 2604 VM_BUG_ON(freeze && !folio); 2605 2606 /* 2607 * When the caller requests to set up a migration entry, we 2608 * require a folio to check the PMD against. Otherwise, there 2609 * is a risk of replacing the wrong folio. 2610 */ 2611 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || 2612 is_pmd_migration_entry(*pmd)) { 2613 if (folio && folio != pmd_folio(*pmd)) 2614 return; 2615 __split_huge_pmd_locked(vma, pmd, address, freeze); 2616 } 2617 } 2618 2619 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2620 unsigned long address, bool freeze, struct folio *folio) 2621 { 2622 spinlock_t *ptl; 2623 struct mmu_notifier_range range; 2624 2625 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, 2626 address & HPAGE_PMD_MASK, 2627 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2628 mmu_notifier_invalidate_range_start(&range); 2629 ptl = pmd_lock(vma->vm_mm, pmd); 2630 split_huge_pmd_locked(vma, range.start, pmd, freeze, folio); 2631 spin_unlock(ptl); 2632 mmu_notifier_invalidate_range_end(&range); 2633 } 2634 2635 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2636 bool freeze, struct folio *folio) 2637 { 2638 pmd_t *pmd = mm_find_pmd(vma->vm_mm, address); 2639 2640 if (!pmd) 2641 return; 2642 2643 __split_huge_pmd(vma, pmd, address, freeze, folio); 2644 } 2645 2646 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) 2647 { 2648 /* 2649 * If the new address isn't hpage aligned and it could previously 2650 * contain an hugepage: check if we need to split an huge pmd. 2651 */ 2652 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && 2653 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), 2654 ALIGN(address, HPAGE_PMD_SIZE))) 2655 split_huge_pmd_address(vma, address, false, NULL); 2656 } 2657 2658 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2659 unsigned long start, 2660 unsigned long end, 2661 long adjust_next) 2662 { 2663 /* Check if we need to split start first. */ 2664 split_huge_pmd_if_needed(vma, start); 2665 2666 /* Check if we need to split end next. */ 2667 split_huge_pmd_if_needed(vma, end); 2668 2669 /* 2670 * If we're also updating the next vma vm_start, 2671 * check if we need to split it. 2672 */ 2673 if (adjust_next > 0) { 2674 struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end); 2675 unsigned long nstart = next->vm_start; 2676 nstart += adjust_next; 2677 split_huge_pmd_if_needed(next, nstart); 2678 } 2679 } 2680 2681 static void unmap_folio(struct folio *folio) 2682 { 2683 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SYNC | 2684 TTU_BATCH_FLUSH; 2685 2686 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 2687 2688 if (folio_test_pmd_mappable(folio)) 2689 ttu_flags |= TTU_SPLIT_HUGE_PMD; 2690 2691 /* 2692 * Anon pages need migration entries to preserve them, but file 2693 * pages can simply be left unmapped, then faulted back on demand. 2694 * If that is ever changed (perhaps for mlock), update remap_page(). 2695 */ 2696 if (folio_test_anon(folio)) 2697 try_to_migrate(folio, ttu_flags); 2698 else 2699 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); 2700 2701 try_to_unmap_flush(); 2702 } 2703 2704 static bool __discard_anon_folio_pmd_locked(struct vm_area_struct *vma, 2705 unsigned long addr, pmd_t *pmdp, 2706 struct folio *folio) 2707 { 2708 struct mm_struct *mm = vma->vm_mm; 2709 int ref_count, map_count; 2710 pmd_t orig_pmd = *pmdp; 2711 2712 if (folio_test_dirty(folio) || pmd_dirty(orig_pmd)) 2713 return false; 2714 2715 orig_pmd = pmdp_huge_clear_flush(vma, addr, pmdp); 2716 2717 /* 2718 * Syncing against concurrent GUP-fast: 2719 * - clear PMD; barrier; read refcount 2720 * - inc refcount; barrier; read PMD 2721 */ 2722 smp_mb(); 2723 2724 ref_count = folio_ref_count(folio); 2725 map_count = folio_mapcount(folio); 2726 2727 /* 2728 * Order reads for folio refcount and dirty flag 2729 * (see comments in __remove_mapping()). 2730 */ 2731 smp_rmb(); 2732 2733 /* 2734 * If the folio or its PMD is redirtied at this point, or if there 2735 * are unexpected references, we will give up to discard this folio 2736 * and remap it. 2737 * 2738 * The only folio refs must be one from isolation plus the rmap(s). 2739 */ 2740 if (folio_test_dirty(folio) || pmd_dirty(orig_pmd) || 2741 ref_count != map_count + 1) { 2742 set_pmd_at(mm, addr, pmdp, orig_pmd); 2743 return false; 2744 } 2745 2746 folio_remove_rmap_pmd(folio, pmd_page(orig_pmd), vma); 2747 zap_deposited_table(mm, pmdp); 2748 add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR); 2749 if (vma->vm_flags & VM_LOCKED) 2750 mlock_drain_local(); 2751 folio_put(folio); 2752 2753 return true; 2754 } 2755 2756 bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr, 2757 pmd_t *pmdp, struct folio *folio) 2758 { 2759 VM_WARN_ON_FOLIO(!folio_test_pmd_mappable(folio), folio); 2760 VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); 2761 VM_WARN_ON_ONCE(!IS_ALIGNED(addr, HPAGE_PMD_SIZE)); 2762 2763 if (folio_test_anon(folio) && !folio_test_swapbacked(folio)) 2764 return __discard_anon_folio_pmd_locked(vma, addr, pmdp, folio); 2765 2766 return false; 2767 } 2768 2769 static void remap_page(struct folio *folio, unsigned long nr) 2770 { 2771 int i = 0; 2772 2773 /* If unmap_folio() uses try_to_migrate() on file, remove this check */ 2774 if (!folio_test_anon(folio)) 2775 return; 2776 for (;;) { 2777 remove_migration_ptes(folio, folio, true); 2778 i += folio_nr_pages(folio); 2779 if (i >= nr) 2780 break; 2781 folio = folio_next(folio); 2782 } 2783 } 2784 2785 static void lru_add_page_tail(struct page *head, struct page *tail, 2786 struct lruvec *lruvec, struct list_head *list) 2787 { 2788 VM_BUG_ON_PAGE(!PageHead(head), head); 2789 VM_BUG_ON_PAGE(PageLRU(tail), head); 2790 lockdep_assert_held(&lruvec->lru_lock); 2791 2792 if (list) { 2793 /* page reclaim is reclaiming a huge page */ 2794 VM_WARN_ON(PageLRU(head)); 2795 get_page(tail); 2796 list_add_tail(&tail->lru, list); 2797 } else { 2798 /* head is still on lru (and we have it frozen) */ 2799 VM_WARN_ON(!PageLRU(head)); 2800 if (PageUnevictable(tail)) 2801 tail->mlock_count = 0; 2802 else 2803 list_add_tail(&tail->lru, &head->lru); 2804 SetPageLRU(tail); 2805 } 2806 } 2807 2808 static void __split_huge_page_tail(struct folio *folio, int tail, 2809 struct lruvec *lruvec, struct list_head *list, 2810 unsigned int new_order) 2811 { 2812 struct page *head = &folio->page; 2813 struct page *page_tail = head + tail; 2814 /* 2815 * Careful: new_folio is not a "real" folio before we cleared PageTail. 2816 * Don't pass it around before clear_compound_head(). 2817 */ 2818 struct folio *new_folio = (struct folio *)page_tail; 2819 2820 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2821 2822 /* 2823 * Clone page flags before unfreezing refcount. 2824 * 2825 * After successful get_page_unless_zero() might follow flags change, 2826 * for example lock_page() which set PG_waiters. 2827 * 2828 * Note that for mapped sub-pages of an anonymous THP, 2829 * PG_anon_exclusive has been cleared in unmap_folio() and is stored in 2830 * the migration entry instead from where remap_page() will restore it. 2831 * We can still have PG_anon_exclusive set on effectively unmapped and 2832 * unreferenced sub-pages of an anonymous THP: we can simply drop 2833 * PG_anon_exclusive (-> PG_mappedtodisk) for these here. 2834 */ 2835 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2836 page_tail->flags |= (head->flags & 2837 ((1L << PG_referenced) | 2838 (1L << PG_swapbacked) | 2839 (1L << PG_swapcache) | 2840 (1L << PG_mlocked) | 2841 (1L << PG_uptodate) | 2842 (1L << PG_active) | 2843 (1L << PG_workingset) | 2844 (1L << PG_locked) | 2845 (1L << PG_unevictable) | 2846 #ifdef CONFIG_ARCH_USES_PG_ARCH_X 2847 (1L << PG_arch_2) | 2848 (1L << PG_arch_3) | 2849 #endif 2850 (1L << PG_dirty) | 2851 LRU_GEN_MASK | LRU_REFS_MASK)); 2852 2853 /* ->mapping in first and second tail page is replaced by other uses */ 2854 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2855 page_tail); 2856 page_tail->mapping = head->mapping; 2857 page_tail->index = head->index + tail; 2858 2859 /* 2860 * page->private should not be set in tail pages. Fix up and warn once 2861 * if private is unexpectedly set. 2862 */ 2863 if (unlikely(page_tail->private)) { 2864 VM_WARN_ON_ONCE_PAGE(true, page_tail); 2865 page_tail->private = 0; 2866 } 2867 if (folio_test_swapcache(folio)) 2868 new_folio->swap.val = folio->swap.val + tail; 2869 2870 /* Page flags must be visible before we make the page non-compound. */ 2871 smp_wmb(); 2872 2873 /* 2874 * Clear PageTail before unfreezing page refcount. 2875 * 2876 * After successful get_page_unless_zero() might follow put_page() 2877 * which needs correct compound_head(). 2878 */ 2879 clear_compound_head(page_tail); 2880 if (new_order) { 2881 prep_compound_page(page_tail, new_order); 2882 folio_set_large_rmappable(new_folio); 2883 } 2884 2885 /* Finally unfreeze refcount. Additional reference from page cache. */ 2886 page_ref_unfreeze(page_tail, 2887 1 + ((!folio_test_anon(folio) || folio_test_swapcache(folio)) ? 2888 folio_nr_pages(new_folio) : 0)); 2889 2890 if (folio_test_young(folio)) 2891 folio_set_young(new_folio); 2892 if (folio_test_idle(folio)) 2893 folio_set_idle(new_folio); 2894 2895 folio_xchg_last_cpupid(new_folio, folio_last_cpupid(folio)); 2896 2897 /* 2898 * always add to the tail because some iterators expect new 2899 * pages to show after the currently processed elements - e.g. 2900 * migrate_pages 2901 */ 2902 lru_add_page_tail(head, page_tail, lruvec, list); 2903 } 2904 2905 static void __split_huge_page(struct page *page, struct list_head *list, 2906 pgoff_t end, unsigned int new_order) 2907 { 2908 struct folio *folio = page_folio(page); 2909 struct page *head = &folio->page; 2910 struct lruvec *lruvec; 2911 struct address_space *swap_cache = NULL; 2912 unsigned long offset = 0; 2913 int i, nr_dropped = 0; 2914 unsigned int new_nr = 1 << new_order; 2915 int order = folio_order(folio); 2916 unsigned int nr = 1 << order; 2917 2918 /* complete memcg works before add pages to LRU */ 2919 split_page_memcg(head, order, new_order); 2920 2921 if (folio_test_anon(folio) && folio_test_swapcache(folio)) { 2922 offset = swap_cache_index(folio->swap); 2923 swap_cache = swap_address_space(folio->swap); 2924 xa_lock(&swap_cache->i_pages); 2925 } 2926 2927 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ 2928 lruvec = folio_lruvec_lock(folio); 2929 2930 ClearPageHasHWPoisoned(head); 2931 2932 for (i = nr - new_nr; i >= new_nr; i -= new_nr) { 2933 __split_huge_page_tail(folio, i, lruvec, list, new_order); 2934 /* Some pages can be beyond EOF: drop them from page cache */ 2935 if (head[i].index >= end) { 2936 struct folio *tail = page_folio(head + i); 2937 2938 if (shmem_mapping(folio->mapping)) 2939 nr_dropped++; 2940 else if (folio_test_clear_dirty(tail)) 2941 folio_account_cleaned(tail, 2942 inode_to_wb(folio->mapping->host)); 2943 __filemap_remove_folio(tail, NULL); 2944 folio_put(tail); 2945 } else if (!PageAnon(page)) { 2946 __xa_store(&folio->mapping->i_pages, head[i].index, 2947 head + i, 0); 2948 } else if (swap_cache) { 2949 __xa_store(&swap_cache->i_pages, offset + i, 2950 head + i, 0); 2951 } 2952 } 2953 2954 if (!new_order) 2955 ClearPageCompound(head); 2956 else { 2957 struct folio *new_folio = (struct folio *)head; 2958 2959 folio_set_order(new_folio, new_order); 2960 } 2961 unlock_page_lruvec(lruvec); 2962 /* Caller disabled irqs, so they are still disabled here */ 2963 2964 split_page_owner(head, order, new_order); 2965 pgalloc_tag_split(head, 1 << order); 2966 2967 /* See comment in __split_huge_page_tail() */ 2968 if (folio_test_anon(folio)) { 2969 /* Additional pin to swap cache */ 2970 if (folio_test_swapcache(folio)) { 2971 folio_ref_add(folio, 1 + new_nr); 2972 xa_unlock(&swap_cache->i_pages); 2973 } else { 2974 folio_ref_inc(folio); 2975 } 2976 } else { 2977 /* Additional pin to page cache */ 2978 folio_ref_add(folio, 1 + new_nr); 2979 xa_unlock(&folio->mapping->i_pages); 2980 } 2981 local_irq_enable(); 2982 2983 if (nr_dropped) 2984 shmem_uncharge(folio->mapping->host, nr_dropped); 2985 remap_page(folio, nr); 2986 2987 /* 2988 * set page to its compound_head when split to non order-0 pages, so 2989 * we can skip unlocking it below, since PG_locked is transferred to 2990 * the compound_head of the page and the caller will unlock it. 2991 */ 2992 if (new_order) 2993 page = compound_head(page); 2994 2995 for (i = 0; i < nr; i += new_nr) { 2996 struct page *subpage = head + i; 2997 struct folio *new_folio = page_folio(subpage); 2998 if (subpage == page) 2999 continue; 3000 folio_unlock(new_folio); 3001 3002 /* 3003 * Subpages may be freed if there wasn't any mapping 3004 * like if add_to_swap() is running on a lru page that 3005 * had its mapping zapped. And freeing these pages 3006 * requires taking the lru_lock so we do the put_page 3007 * of the tail pages after the split is complete. 3008 */ 3009 free_page_and_swap_cache(subpage); 3010 } 3011 } 3012 3013 /* Racy check whether the huge page can be split */ 3014 bool can_split_folio(struct folio *folio, int caller_pins, int *pextra_pins) 3015 { 3016 int extra_pins; 3017 3018 /* Additional pins from page cache */ 3019 if (folio_test_anon(folio)) 3020 extra_pins = folio_test_swapcache(folio) ? 3021 folio_nr_pages(folio) : 0; 3022 else 3023 extra_pins = folio_nr_pages(folio); 3024 if (pextra_pins) 3025 *pextra_pins = extra_pins; 3026 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 3027 caller_pins; 3028 } 3029 3030 /* 3031 * This function splits a large folio into smaller folios of order @new_order. 3032 * @page can point to any page of the large folio to split. The split operation 3033 * does not change the position of @page. 3034 * 3035 * Prerequisites: 3036 * 3037 * 1) The caller must hold a reference on the @page's owning folio, also known 3038 * as the large folio. 3039 * 3040 * 2) The large folio must be locked. 3041 * 3042 * 3) The folio must not be pinned. Any unexpected folio references, including 3043 * GUP pins, will result in the folio not getting split; instead, the caller 3044 * will receive an -EAGAIN. 3045 * 3046 * 4) @new_order > 1, usually. Splitting to order-1 anonymous folios is not 3047 * supported for non-file-backed folios, because folio->_deferred_list, which 3048 * is used by partially mapped folios, is stored in subpage 2, but an order-1 3049 * folio only has subpages 0 and 1. File-backed order-1 folios are supported, 3050 * since they do not use _deferred_list. 3051 * 3052 * After splitting, the caller's folio reference will be transferred to @page, 3053 * resulting in a raised refcount of @page after this call. The other pages may 3054 * be freed if they are not mapped. 3055 * 3056 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 3057 * 3058 * Pages in @new_order will inherit the mapping, flags, and so on from the 3059 * huge page. 3060 * 3061 * Returns 0 if the huge page was split successfully. 3062 * 3063 * Returns -EAGAIN if the folio has unexpected reference (e.g., GUP) or if 3064 * the folio was concurrently removed from the page cache. 3065 * 3066 * Returns -EBUSY when trying to split the huge zeropage, if the folio is 3067 * under writeback, if fs-specific folio metadata cannot currently be 3068 * released, or if some unexpected race happened (e.g., anon VMA disappeared, 3069 * truncation). 3070 * 3071 * Returns -EINVAL when trying to split to an order that is incompatible 3072 * with the folio. Splitting to order 0 is compatible with all folios. 3073 */ 3074 int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, 3075 unsigned int new_order) 3076 { 3077 struct folio *folio = page_folio(page); 3078 struct deferred_split *ds_queue = get_deferred_split_queue(folio); 3079 /* reset xarray order to new order after split */ 3080 XA_STATE_ORDER(xas, &folio->mapping->i_pages, folio->index, new_order); 3081 struct anon_vma *anon_vma = NULL; 3082 struct address_space *mapping = NULL; 3083 int order = folio_order(folio); 3084 int extra_pins, ret; 3085 pgoff_t end; 3086 bool is_hzp; 3087 3088 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); 3089 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 3090 3091 if (new_order >= folio_order(folio)) 3092 return -EINVAL; 3093 3094 if (folio_test_anon(folio)) { 3095 /* order-1 is not supported for anonymous THP. */ 3096 if (new_order == 1) { 3097 VM_WARN_ONCE(1, "Cannot split to order-1 folio"); 3098 return -EINVAL; 3099 } 3100 } else if (new_order) { 3101 /* Split shmem folio to non-zero order not supported */ 3102 if (shmem_mapping(folio->mapping)) { 3103 VM_WARN_ONCE(1, 3104 "Cannot split shmem folio to non-0 order"); 3105 return -EINVAL; 3106 } 3107 /* 3108 * No split if the file system does not support large folio. 3109 * Note that we might still have THPs in such mappings due to 3110 * CONFIG_READ_ONLY_THP_FOR_FS. But in that case, the mapping 3111 * does not actually support large folios properly. 3112 */ 3113 if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && 3114 !mapping_large_folio_support(folio->mapping)) { 3115 VM_WARN_ONCE(1, 3116 "Cannot split file folio to non-0 order"); 3117 return -EINVAL; 3118 } 3119 } 3120 3121 /* Only swapping a whole PMD-mapped folio is supported */ 3122 if (folio_test_swapcache(folio) && new_order) 3123 return -EINVAL; 3124 3125 is_hzp = is_huge_zero_folio(folio); 3126 if (is_hzp) { 3127 pr_warn_ratelimited("Called split_huge_page for huge zero page\n"); 3128 return -EBUSY; 3129 } 3130 3131 if (folio_test_writeback(folio)) 3132 return -EBUSY; 3133 3134 if (folio_test_anon(folio)) { 3135 /* 3136 * The caller does not necessarily hold an mmap_lock that would 3137 * prevent the anon_vma disappearing so we first we take a 3138 * reference to it and then lock the anon_vma for write. This 3139 * is similar to folio_lock_anon_vma_read except the write lock 3140 * is taken to serialise against parallel split or collapse 3141 * operations. 3142 */ 3143 anon_vma = folio_get_anon_vma(folio); 3144 if (!anon_vma) { 3145 ret = -EBUSY; 3146 goto out; 3147 } 3148 end = -1; 3149 mapping = NULL; 3150 anon_vma_lock_write(anon_vma); 3151 } else { 3152 gfp_t gfp; 3153 3154 mapping = folio->mapping; 3155 3156 /* Truncated ? */ 3157 if (!mapping) { 3158 ret = -EBUSY; 3159 goto out; 3160 } 3161 3162 gfp = current_gfp_context(mapping_gfp_mask(mapping) & 3163 GFP_RECLAIM_MASK); 3164 3165 if (!filemap_release_folio(folio, gfp)) { 3166 ret = -EBUSY; 3167 goto out; 3168 } 3169 3170 xas_split_alloc(&xas, folio, folio_order(folio), gfp); 3171 if (xas_error(&xas)) { 3172 ret = xas_error(&xas); 3173 goto out; 3174 } 3175 3176 anon_vma = NULL; 3177 i_mmap_lock_read(mapping); 3178 3179 /* 3180 *__split_huge_page() may need to trim off pages beyond EOF: 3181 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 3182 * which cannot be nested inside the page tree lock. So note 3183 * end now: i_size itself may be changed at any moment, but 3184 * folio lock is good enough to serialize the trimming. 3185 */ 3186 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 3187 if (shmem_mapping(mapping)) 3188 end = shmem_fallocend(mapping->host, end); 3189 } 3190 3191 /* 3192 * Racy check if we can split the page, before unmap_folio() will 3193 * split PMDs 3194 */ 3195 if (!can_split_folio(folio, 1, &extra_pins)) { 3196 ret = -EAGAIN; 3197 goto out_unlock; 3198 } 3199 3200 unmap_folio(folio); 3201 3202 /* block interrupt reentry in xa_lock and spinlock */ 3203 local_irq_disable(); 3204 if (mapping) { 3205 /* 3206 * Check if the folio is present in page cache. 3207 * We assume all tail are present too, if folio is there. 3208 */ 3209 xas_lock(&xas); 3210 xas_reset(&xas); 3211 if (xas_load(&xas) != folio) 3212 goto fail; 3213 } 3214 3215 /* Prevent deferred_split_scan() touching ->_refcount */ 3216 spin_lock(&ds_queue->split_queue_lock); 3217 if (folio_ref_freeze(folio, 1 + extra_pins)) { 3218 if (folio_order(folio) > 1 && 3219 !list_empty(&folio->_deferred_list)) { 3220 ds_queue->split_queue_len--; 3221 /* 3222 * Reinitialize page_deferred_list after removing the 3223 * page from the split_queue, otherwise a subsequent 3224 * split will see list corruption when checking the 3225 * page_deferred_list. 3226 */ 3227 list_del_init(&folio->_deferred_list); 3228 } 3229 spin_unlock(&ds_queue->split_queue_lock); 3230 if (mapping) { 3231 int nr = folio_nr_pages(folio); 3232 3233 xas_split(&xas, folio, folio_order(folio)); 3234 if (folio_test_pmd_mappable(folio) && 3235 new_order < HPAGE_PMD_ORDER) { 3236 if (folio_test_swapbacked(folio)) { 3237 __lruvec_stat_mod_folio(folio, 3238 NR_SHMEM_THPS, -nr); 3239 } else { 3240 __lruvec_stat_mod_folio(folio, 3241 NR_FILE_THPS, -nr); 3242 filemap_nr_thps_dec(mapping); 3243 } 3244 } 3245 } 3246 3247 __split_huge_page(page, list, end, new_order); 3248 ret = 0; 3249 } else { 3250 spin_unlock(&ds_queue->split_queue_lock); 3251 fail: 3252 if (mapping) 3253 xas_unlock(&xas); 3254 local_irq_enable(); 3255 remap_page(folio, folio_nr_pages(folio)); 3256 ret = -EAGAIN; 3257 } 3258 3259 out_unlock: 3260 if (anon_vma) { 3261 anon_vma_unlock_write(anon_vma); 3262 put_anon_vma(anon_vma); 3263 } 3264 if (mapping) 3265 i_mmap_unlock_read(mapping); 3266 out: 3267 xas_destroy(&xas); 3268 if (order == HPAGE_PMD_ORDER) 3269 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 3270 count_mthp_stat(order, !ret ? MTHP_STAT_SPLIT : MTHP_STAT_SPLIT_FAILED); 3271 return ret; 3272 } 3273 3274 void __folio_undo_large_rmappable(struct folio *folio) 3275 { 3276 struct deferred_split *ds_queue; 3277 unsigned long flags; 3278 3279 ds_queue = get_deferred_split_queue(folio); 3280 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3281 if (!list_empty(&folio->_deferred_list)) { 3282 ds_queue->split_queue_len--; 3283 list_del_init(&folio->_deferred_list); 3284 } 3285 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3286 } 3287 3288 void deferred_split_folio(struct folio *folio) 3289 { 3290 struct deferred_split *ds_queue = get_deferred_split_queue(folio); 3291 #ifdef CONFIG_MEMCG 3292 struct mem_cgroup *memcg = folio_memcg(folio); 3293 #endif 3294 unsigned long flags; 3295 3296 /* 3297 * Order 1 folios have no space for a deferred list, but we also 3298 * won't waste much memory by not adding them to the deferred list. 3299 */ 3300 if (folio_order(folio) <= 1) 3301 return; 3302 3303 /* 3304 * The try_to_unmap() in page reclaim path might reach here too, 3305 * this may cause a race condition to corrupt deferred split queue. 3306 * And, if page reclaim is already handling the same folio, it is 3307 * unnecessary to handle it again in shrinker. 3308 * 3309 * Check the swapcache flag to determine if the folio is being 3310 * handled by page reclaim since THP swap would add the folio into 3311 * swap cache before calling try_to_unmap(). 3312 */ 3313 if (folio_test_swapcache(folio)) 3314 return; 3315 3316 if (!list_empty(&folio->_deferred_list)) 3317 return; 3318 3319 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3320 if (list_empty(&folio->_deferred_list)) { 3321 if (folio_test_pmd_mappable(folio)) 3322 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 3323 count_mthp_stat(folio_order(folio), MTHP_STAT_SPLIT_DEFERRED); 3324 list_add_tail(&folio->_deferred_list, &ds_queue->split_queue); 3325 ds_queue->split_queue_len++; 3326 #ifdef CONFIG_MEMCG 3327 if (memcg) 3328 set_shrinker_bit(memcg, folio_nid(folio), 3329 deferred_split_shrinker->id); 3330 #endif 3331 } 3332 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3333 } 3334 3335 static unsigned long deferred_split_count(struct shrinker *shrink, 3336 struct shrink_control *sc) 3337 { 3338 struct pglist_data *pgdata = NODE_DATA(sc->nid); 3339 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 3340 3341 #ifdef CONFIG_MEMCG 3342 if (sc->memcg) 3343 ds_queue = &sc->memcg->deferred_split_queue; 3344 #endif 3345 return READ_ONCE(ds_queue->split_queue_len); 3346 } 3347 3348 static unsigned long deferred_split_scan(struct shrinker *shrink, 3349 struct shrink_control *sc) 3350 { 3351 struct pglist_data *pgdata = NODE_DATA(sc->nid); 3352 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 3353 unsigned long flags; 3354 LIST_HEAD(list); 3355 struct folio *folio, *next; 3356 int split = 0; 3357 3358 #ifdef CONFIG_MEMCG 3359 if (sc->memcg) 3360 ds_queue = &sc->memcg->deferred_split_queue; 3361 #endif 3362 3363 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3364 /* Take pin on all head pages to avoid freeing them under us */ 3365 list_for_each_entry_safe(folio, next, &ds_queue->split_queue, 3366 _deferred_list) { 3367 if (folio_try_get(folio)) { 3368 list_move(&folio->_deferred_list, &list); 3369 } else { 3370 /* We lost race with folio_put() */ 3371 list_del_init(&folio->_deferred_list); 3372 ds_queue->split_queue_len--; 3373 } 3374 if (!--sc->nr_to_scan) 3375 break; 3376 } 3377 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3378 3379 list_for_each_entry_safe(folio, next, &list, _deferred_list) { 3380 if (!folio_trylock(folio)) 3381 goto next; 3382 /* split_huge_page() removes page from list on success */ 3383 if (!split_folio(folio)) 3384 split++; 3385 folio_unlock(folio); 3386 next: 3387 folio_put(folio); 3388 } 3389 3390 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3391 list_splice_tail(&list, &ds_queue->split_queue); 3392 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3393 3394 /* 3395 * Stop shrinker if we didn't split any page, but the queue is empty. 3396 * This can happen if pages were freed under us. 3397 */ 3398 if (!split && list_empty(&ds_queue->split_queue)) 3399 return SHRINK_STOP; 3400 return split; 3401 } 3402 3403 #ifdef CONFIG_DEBUG_FS 3404 static void split_huge_pages_all(void) 3405 { 3406 struct zone *zone; 3407 struct page *page; 3408 struct folio *folio; 3409 unsigned long pfn, max_zone_pfn; 3410 unsigned long total = 0, split = 0; 3411 3412 pr_debug("Split all THPs\n"); 3413 for_each_zone(zone) { 3414 if (!managed_zone(zone)) 3415 continue; 3416 max_zone_pfn = zone_end_pfn(zone); 3417 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 3418 int nr_pages; 3419 3420 page = pfn_to_online_page(pfn); 3421 if (!page || PageTail(page)) 3422 continue; 3423 folio = page_folio(page); 3424 if (!folio_try_get(folio)) 3425 continue; 3426 3427 if (unlikely(page_folio(page) != folio)) 3428 goto next; 3429 3430 if (zone != folio_zone(folio)) 3431 goto next; 3432 3433 if (!folio_test_large(folio) 3434 || folio_test_hugetlb(folio) 3435 || !folio_test_lru(folio)) 3436 goto next; 3437 3438 total++; 3439 folio_lock(folio); 3440 nr_pages = folio_nr_pages(folio); 3441 if (!split_folio(folio)) 3442 split++; 3443 pfn += nr_pages - 1; 3444 folio_unlock(folio); 3445 next: 3446 folio_put(folio); 3447 cond_resched(); 3448 } 3449 } 3450 3451 pr_debug("%lu of %lu THP split\n", split, total); 3452 } 3453 3454 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) 3455 { 3456 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || 3457 is_vm_hugetlb_page(vma); 3458 } 3459 3460 static int split_huge_pages_pid(int pid, unsigned long vaddr_start, 3461 unsigned long vaddr_end, unsigned int new_order) 3462 { 3463 int ret = 0; 3464 struct task_struct *task; 3465 struct mm_struct *mm; 3466 unsigned long total = 0, split = 0; 3467 unsigned long addr; 3468 3469 vaddr_start &= PAGE_MASK; 3470 vaddr_end &= PAGE_MASK; 3471 3472 /* Find the task_struct from pid */ 3473 rcu_read_lock(); 3474 task = find_task_by_vpid(pid); 3475 if (!task) { 3476 rcu_read_unlock(); 3477 ret = -ESRCH; 3478 goto out; 3479 } 3480 get_task_struct(task); 3481 rcu_read_unlock(); 3482 3483 /* Find the mm_struct */ 3484 mm = get_task_mm(task); 3485 put_task_struct(task); 3486 3487 if (!mm) { 3488 ret = -EINVAL; 3489 goto out; 3490 } 3491 3492 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n", 3493 pid, vaddr_start, vaddr_end); 3494 3495 mmap_read_lock(mm); 3496 /* 3497 * always increase addr by PAGE_SIZE, since we could have a PTE page 3498 * table filled with PTE-mapped THPs, each of which is distinct. 3499 */ 3500 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { 3501 struct vm_area_struct *vma = vma_lookup(mm, addr); 3502 struct folio_walk fw; 3503 struct folio *folio; 3504 3505 if (!vma) 3506 break; 3507 3508 /* skip special VMA and hugetlb VMA */ 3509 if (vma_not_suitable_for_thp_split(vma)) { 3510 addr = vma->vm_end; 3511 continue; 3512 } 3513 3514 folio = folio_walk_start(&fw, vma, addr, 0); 3515 if (!folio) 3516 continue; 3517 3518 if (!is_transparent_hugepage(folio)) 3519 goto next; 3520 3521 if (new_order >= folio_order(folio)) 3522 goto next; 3523 3524 total++; 3525 /* 3526 * For folios with private, split_huge_page_to_list_to_order() 3527 * will try to drop it before split and then check if the folio 3528 * can be split or not. So skip the check here. 3529 */ 3530 if (!folio_test_private(folio) && 3531 !can_split_folio(folio, 0, NULL)) 3532 goto next; 3533 3534 if (!folio_trylock(folio)) 3535 goto next; 3536 folio_get(folio); 3537 folio_walk_end(&fw, vma); 3538 3539 if (!split_folio_to_order(folio, new_order)) 3540 split++; 3541 3542 folio_unlock(folio); 3543 folio_put(folio); 3544 3545 cond_resched(); 3546 continue; 3547 next: 3548 folio_walk_end(&fw, vma); 3549 cond_resched(); 3550 } 3551 mmap_read_unlock(mm); 3552 mmput(mm); 3553 3554 pr_debug("%lu of %lu THP split\n", split, total); 3555 3556 out: 3557 return ret; 3558 } 3559 3560 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, 3561 pgoff_t off_end, unsigned int new_order) 3562 { 3563 struct filename *file; 3564 struct file *candidate; 3565 struct address_space *mapping; 3566 int ret = -EINVAL; 3567 pgoff_t index; 3568 int nr_pages = 1; 3569 unsigned long total = 0, split = 0; 3570 3571 file = getname_kernel(file_path); 3572 if (IS_ERR(file)) 3573 return ret; 3574 3575 candidate = file_open_name(file, O_RDONLY, 0); 3576 if (IS_ERR(candidate)) 3577 goto out; 3578 3579 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", 3580 file_path, off_start, off_end); 3581 3582 mapping = candidate->f_mapping; 3583 3584 for (index = off_start; index < off_end; index += nr_pages) { 3585 struct folio *folio = filemap_get_folio(mapping, index); 3586 3587 nr_pages = 1; 3588 if (IS_ERR(folio)) 3589 continue; 3590 3591 if (!folio_test_large(folio)) 3592 goto next; 3593 3594 total++; 3595 nr_pages = folio_nr_pages(folio); 3596 3597 if (new_order >= folio_order(folio)) 3598 goto next; 3599 3600 if (!folio_trylock(folio)) 3601 goto next; 3602 3603 if (!split_folio_to_order(folio, new_order)) 3604 split++; 3605 3606 folio_unlock(folio); 3607 next: 3608 folio_put(folio); 3609 cond_resched(); 3610 } 3611 3612 filp_close(candidate, NULL); 3613 ret = 0; 3614 3615 pr_debug("%lu of %lu file-backed THP split\n", split, total); 3616 out: 3617 putname(file); 3618 return ret; 3619 } 3620 3621 #define MAX_INPUT_BUF_SZ 255 3622 3623 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, 3624 size_t count, loff_t *ppops) 3625 { 3626 static DEFINE_MUTEX(split_debug_mutex); 3627 ssize_t ret; 3628 /* 3629 * hold pid, start_vaddr, end_vaddr, new_order or 3630 * file_path, off_start, off_end, new_order 3631 */ 3632 char input_buf[MAX_INPUT_BUF_SZ]; 3633 int pid; 3634 unsigned long vaddr_start, vaddr_end; 3635 unsigned int new_order = 0; 3636 3637 ret = mutex_lock_interruptible(&split_debug_mutex); 3638 if (ret) 3639 return ret; 3640 3641 ret = -EFAULT; 3642 3643 memset(input_buf, 0, MAX_INPUT_BUF_SZ); 3644 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) 3645 goto out; 3646 3647 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; 3648 3649 if (input_buf[0] == '/') { 3650 char *tok; 3651 char *buf = input_buf; 3652 char file_path[MAX_INPUT_BUF_SZ]; 3653 pgoff_t off_start = 0, off_end = 0; 3654 size_t input_len = strlen(input_buf); 3655 3656 tok = strsep(&buf, ","); 3657 if (tok) { 3658 strcpy(file_path, tok); 3659 } else { 3660 ret = -EINVAL; 3661 goto out; 3662 } 3663 3664 ret = sscanf(buf, "0x%lx,0x%lx,%d", &off_start, &off_end, &new_order); 3665 if (ret != 2 && ret != 3) { 3666 ret = -EINVAL; 3667 goto out; 3668 } 3669 ret = split_huge_pages_in_file(file_path, off_start, off_end, new_order); 3670 if (!ret) 3671 ret = input_len; 3672 3673 goto out; 3674 } 3675 3676 ret = sscanf(input_buf, "%d,0x%lx,0x%lx,%d", &pid, &vaddr_start, &vaddr_end, &new_order); 3677 if (ret == 1 && pid == 1) { 3678 split_huge_pages_all(); 3679 ret = strlen(input_buf); 3680 goto out; 3681 } else if (ret != 3 && ret != 4) { 3682 ret = -EINVAL; 3683 goto out; 3684 } 3685 3686 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end, new_order); 3687 if (!ret) 3688 ret = strlen(input_buf); 3689 out: 3690 mutex_unlock(&split_debug_mutex); 3691 return ret; 3692 3693 } 3694 3695 static const struct file_operations split_huge_pages_fops = { 3696 .owner = THIS_MODULE, 3697 .write = split_huge_pages_write, 3698 .llseek = no_llseek, 3699 }; 3700 3701 static int __init split_huge_pages_debugfs(void) 3702 { 3703 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 3704 &split_huge_pages_fops); 3705 return 0; 3706 } 3707 late_initcall(split_huge_pages_debugfs); 3708 #endif 3709 3710 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 3711 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 3712 struct page *page) 3713 { 3714 struct folio *folio = page_folio(page); 3715 struct vm_area_struct *vma = pvmw->vma; 3716 struct mm_struct *mm = vma->vm_mm; 3717 unsigned long address = pvmw->address; 3718 bool anon_exclusive; 3719 pmd_t pmdval; 3720 swp_entry_t entry; 3721 pmd_t pmdswp; 3722 3723 if (!(pvmw->pmd && !pvmw->pte)) 3724 return 0; 3725 3726 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 3727 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 3728 3729 /* See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */ 3730 anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(page); 3731 if (anon_exclusive && folio_try_share_anon_rmap_pmd(folio, page)) { 3732 set_pmd_at(mm, address, pvmw->pmd, pmdval); 3733 return -EBUSY; 3734 } 3735 3736 if (pmd_dirty(pmdval)) 3737 folio_mark_dirty(folio); 3738 if (pmd_write(pmdval)) 3739 entry = make_writable_migration_entry(page_to_pfn(page)); 3740 else if (anon_exclusive) 3741 entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); 3742 else 3743 entry = make_readable_migration_entry(page_to_pfn(page)); 3744 if (pmd_young(pmdval)) 3745 entry = make_migration_entry_young(entry); 3746 if (pmd_dirty(pmdval)) 3747 entry = make_migration_entry_dirty(entry); 3748 pmdswp = swp_entry_to_pmd(entry); 3749 if (pmd_soft_dirty(pmdval)) 3750 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3751 if (pmd_uffd_wp(pmdval)) 3752 pmdswp = pmd_swp_mkuffd_wp(pmdswp); 3753 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3754 folio_remove_rmap_pmd(folio, page, vma); 3755 folio_put(folio); 3756 trace_set_migration_pmd(address, pmd_val(pmdswp)); 3757 3758 return 0; 3759 } 3760 3761 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3762 { 3763 struct folio *folio = page_folio(new); 3764 struct vm_area_struct *vma = pvmw->vma; 3765 struct mm_struct *mm = vma->vm_mm; 3766 unsigned long address = pvmw->address; 3767 unsigned long haddr = address & HPAGE_PMD_MASK; 3768 pmd_t pmde; 3769 swp_entry_t entry; 3770 3771 if (!(pvmw->pmd && !pvmw->pte)) 3772 return; 3773 3774 entry = pmd_to_swp_entry(*pvmw->pmd); 3775 folio_get(folio); 3776 pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot)); 3777 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3778 pmde = pmd_mksoft_dirty(pmde); 3779 if (is_writable_migration_entry(entry)) 3780 pmde = pmd_mkwrite(pmde, vma); 3781 if (pmd_swp_uffd_wp(*pvmw->pmd)) 3782 pmde = pmd_mkuffd_wp(pmde); 3783 if (!is_migration_entry_young(entry)) 3784 pmde = pmd_mkold(pmde); 3785 /* NOTE: this may contain setting soft-dirty on some archs */ 3786 if (folio_test_dirty(folio) && is_migration_entry_dirty(entry)) 3787 pmde = pmd_mkdirty(pmde); 3788 3789 if (folio_test_anon(folio)) { 3790 rmap_t rmap_flags = RMAP_NONE; 3791 3792 if (!is_readable_migration_entry(entry)) 3793 rmap_flags |= RMAP_EXCLUSIVE; 3794 3795 folio_add_anon_rmap_pmd(folio, new, vma, haddr, rmap_flags); 3796 } else { 3797 folio_add_file_rmap_pmd(folio, new, vma); 3798 } 3799 VM_BUG_ON(pmd_write(pmde) && folio_test_anon(folio) && !PageAnonExclusive(new)); 3800 set_pmd_at(mm, haddr, pvmw->pmd, pmde); 3801 3802 /* No need to invalidate - it was non-present before */ 3803 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3804 trace_remove_migration_pmd(address, pmd_val(pmde)); 3805 } 3806 #endif 3807