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 44 #include <asm/tlb.h> 45 #include <asm/pgalloc.h> 46 #include "internal.h" 47 #include "swap.h" 48 49 #define CREATE_TRACE_POINTS 50 #include <trace/events/thp.h> 51 52 /* 53 * By default, transparent hugepage support is disabled in order to avoid 54 * risking an increased memory footprint for applications that are not 55 * guaranteed to benefit from it. When transparent hugepage support is 56 * enabled, it is for all mappings, and khugepaged scans all mappings. 57 * Defrag is invoked by khugepaged hugepage allocations and by page faults 58 * for all hugepage allocations. 59 */ 60 unsigned long transparent_hugepage_flags __read_mostly = 61 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 62 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 63 #endif 64 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 65 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 66 #endif 67 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 68 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 69 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 70 71 static struct shrinker *deferred_split_shrinker; 72 static unsigned long deferred_split_count(struct shrinker *shrink, 73 struct shrink_control *sc); 74 static unsigned long deferred_split_scan(struct shrinker *shrink, 75 struct shrink_control *sc); 76 77 static atomic_t huge_zero_refcount; 78 struct folio *huge_zero_folio __read_mostly; 79 unsigned long huge_zero_pfn __read_mostly = ~0UL; 80 unsigned long huge_anon_orders_always __read_mostly; 81 unsigned long huge_anon_orders_madvise __read_mostly; 82 unsigned long huge_anon_orders_inherit __read_mostly; 83 84 unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, 85 unsigned long vm_flags, 86 unsigned long tva_flags, 87 unsigned long orders) 88 { 89 bool smaps = tva_flags & TVA_SMAPS; 90 bool in_pf = tva_flags & TVA_IN_PF; 91 bool enforce_sysfs = tva_flags & TVA_ENFORCE_SYSFS; 92 unsigned long supported_orders; 93 94 /* Check the intersection of requested and supported orders. */ 95 if (vma_is_anonymous(vma)) 96 supported_orders = THP_ORDERS_ALL_ANON; 97 else if (vma_is_dax(vma)) 98 supported_orders = THP_ORDERS_ALL_FILE_DAX; 99 else 100 supported_orders = THP_ORDERS_ALL_FILE_DEFAULT; 101 102 orders &= supported_orders; 103 if (!orders) 104 return 0; 105 106 if (!vma->vm_mm) /* vdso */ 107 return 0; 108 109 /* 110 * Explicitly disabled through madvise or prctl, or some 111 * architectures may disable THP for some mappings, for 112 * example, s390 kvm. 113 * */ 114 if ((vm_flags & VM_NOHUGEPAGE) || 115 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) 116 return 0; 117 /* 118 * If the hardware/firmware marked hugepage support disabled. 119 */ 120 if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED)) 121 return 0; 122 123 /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ 124 if (vma_is_dax(vma)) 125 return in_pf ? orders : 0; 126 127 /* 128 * khugepaged special VMA and hugetlb VMA. 129 * Must be checked after dax since some dax mappings may have 130 * VM_MIXEDMAP set. 131 */ 132 if (!in_pf && !smaps && (vm_flags & VM_NO_KHUGEPAGED)) 133 return 0; 134 135 /* 136 * Check alignment for file vma and size for both file and anon vma by 137 * filtering out the unsuitable orders. 138 * 139 * Skip the check for page fault. Huge fault does the check in fault 140 * handlers. 141 */ 142 if (!in_pf) { 143 int order = highest_order(orders); 144 unsigned long addr; 145 146 while (orders) { 147 addr = vma->vm_end - (PAGE_SIZE << order); 148 if (thp_vma_suitable_order(vma, addr, order)) 149 break; 150 order = next_order(&orders, order); 151 } 152 153 if (!orders) 154 return 0; 155 } 156 157 /* 158 * Enabled via shmem mount options or sysfs settings. 159 * Must be done before hugepage flags check since shmem has its 160 * own flags. 161 */ 162 if (!in_pf && shmem_file(vma->vm_file)) 163 return shmem_allowable_huge_orders(file_inode(vma->vm_file), 164 vma, vma->vm_pgoff, 165 !enforce_sysfs); 166 167 if (!vma_is_anonymous(vma)) { 168 /* 169 * Enforce sysfs THP requirements as necessary. Anonymous vmas 170 * were already handled in thp_vma_allowable_orders(). 171 */ 172 if (enforce_sysfs && 173 (!hugepage_global_enabled() || (!(vm_flags & VM_HUGEPAGE) && 174 !hugepage_global_always()))) 175 return 0; 176 177 /* 178 * Trust that ->huge_fault() handlers know what they are doing 179 * in fault path. 180 */ 181 if (((in_pf || smaps)) && vma->vm_ops->huge_fault) 182 return orders; 183 /* Only regular file is valid in collapse path */ 184 if (((!in_pf || smaps)) && file_thp_enabled(vma)) 185 return orders; 186 return 0; 187 } 188 189 if (vma_is_temporary_stack(vma)) 190 return 0; 191 192 /* 193 * THPeligible bit of smaps should show 1 for proper VMAs even 194 * though anon_vma is not initialized yet. 195 * 196 * Allow page fault since anon_vma may be not initialized until 197 * the first page fault. 198 */ 199 if (!vma->anon_vma) 200 return (smaps || in_pf) ? orders : 0; 201 202 return orders; 203 } 204 205 static bool get_huge_zero_page(void) 206 { 207 struct folio *zero_folio; 208 retry: 209 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 210 return true; 211 212 zero_folio = folio_alloc((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 213 HPAGE_PMD_ORDER); 214 if (!zero_folio) { 215 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 216 return false; 217 } 218 preempt_disable(); 219 if (cmpxchg(&huge_zero_folio, NULL, zero_folio)) { 220 preempt_enable(); 221 folio_put(zero_folio); 222 goto retry; 223 } 224 WRITE_ONCE(huge_zero_pfn, folio_pfn(zero_folio)); 225 226 /* We take additional reference here. It will be put back by shrinker */ 227 atomic_set(&huge_zero_refcount, 2); 228 preempt_enable(); 229 count_vm_event(THP_ZERO_PAGE_ALLOC); 230 return true; 231 } 232 233 static void put_huge_zero_page(void) 234 { 235 /* 236 * Counter should never go to zero here. Only shrinker can put 237 * last reference. 238 */ 239 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 240 } 241 242 struct folio *mm_get_huge_zero_folio(struct mm_struct *mm) 243 { 244 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 245 return READ_ONCE(huge_zero_folio); 246 247 if (!get_huge_zero_page()) 248 return NULL; 249 250 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 251 put_huge_zero_page(); 252 253 return READ_ONCE(huge_zero_folio); 254 } 255 256 void mm_put_huge_zero_folio(struct mm_struct *mm) 257 { 258 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 259 put_huge_zero_page(); 260 } 261 262 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 263 struct shrink_control *sc) 264 { 265 /* we can free zero page only if last reference remains */ 266 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 267 } 268 269 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 270 struct shrink_control *sc) 271 { 272 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 273 struct folio *zero_folio = xchg(&huge_zero_folio, NULL); 274 BUG_ON(zero_folio == NULL); 275 WRITE_ONCE(huge_zero_pfn, ~0UL); 276 folio_put(zero_folio); 277 return HPAGE_PMD_NR; 278 } 279 280 return 0; 281 } 282 283 static struct shrinker *huge_zero_page_shrinker; 284 285 #ifdef CONFIG_SYSFS 286 static ssize_t enabled_show(struct kobject *kobj, 287 struct kobj_attribute *attr, char *buf) 288 { 289 const char *output; 290 291 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 292 output = "[always] madvise never"; 293 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 294 &transparent_hugepage_flags)) 295 output = "always [madvise] never"; 296 else 297 output = "always madvise [never]"; 298 299 return sysfs_emit(buf, "%s\n", output); 300 } 301 302 static ssize_t enabled_store(struct kobject *kobj, 303 struct kobj_attribute *attr, 304 const char *buf, size_t count) 305 { 306 ssize_t ret = count; 307 308 if (sysfs_streq(buf, "always")) { 309 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 310 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 311 } else if (sysfs_streq(buf, "madvise")) { 312 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 313 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 314 } else if (sysfs_streq(buf, "never")) { 315 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 316 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 317 } else 318 ret = -EINVAL; 319 320 if (ret > 0) { 321 int err = start_stop_khugepaged(); 322 if (err) 323 ret = err; 324 } 325 return ret; 326 } 327 328 static struct kobj_attribute enabled_attr = __ATTR_RW(enabled); 329 330 ssize_t single_hugepage_flag_show(struct kobject *kobj, 331 struct kobj_attribute *attr, char *buf, 332 enum transparent_hugepage_flag flag) 333 { 334 return sysfs_emit(buf, "%d\n", 335 !!test_bit(flag, &transparent_hugepage_flags)); 336 } 337 338 ssize_t single_hugepage_flag_store(struct kobject *kobj, 339 struct kobj_attribute *attr, 340 const char *buf, size_t count, 341 enum transparent_hugepage_flag flag) 342 { 343 unsigned long value; 344 int ret; 345 346 ret = kstrtoul(buf, 10, &value); 347 if (ret < 0) 348 return ret; 349 if (value > 1) 350 return -EINVAL; 351 352 if (value) 353 set_bit(flag, &transparent_hugepage_flags); 354 else 355 clear_bit(flag, &transparent_hugepage_flags); 356 357 return count; 358 } 359 360 static ssize_t defrag_show(struct kobject *kobj, 361 struct kobj_attribute *attr, char *buf) 362 { 363 const char *output; 364 365 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 366 &transparent_hugepage_flags)) 367 output = "[always] defer defer+madvise madvise never"; 368 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 369 &transparent_hugepage_flags)) 370 output = "always [defer] defer+madvise madvise never"; 371 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 372 &transparent_hugepage_flags)) 373 output = "always defer [defer+madvise] madvise never"; 374 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 375 &transparent_hugepage_flags)) 376 output = "always defer defer+madvise [madvise] never"; 377 else 378 output = "always defer defer+madvise madvise [never]"; 379 380 return sysfs_emit(buf, "%s\n", output); 381 } 382 383 static ssize_t defrag_store(struct kobject *kobj, 384 struct kobj_attribute *attr, 385 const char *buf, size_t count) 386 { 387 if (sysfs_streq(buf, "always")) { 388 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 389 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 390 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 391 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 392 } else if (sysfs_streq(buf, "defer+madvise")) { 393 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 394 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 395 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 396 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 397 } else if (sysfs_streq(buf, "defer")) { 398 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 399 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 400 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 401 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 402 } else if (sysfs_streq(buf, "madvise")) { 403 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 404 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 405 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 406 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 407 } else if (sysfs_streq(buf, "never")) { 408 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 409 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 410 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 411 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 412 } else 413 return -EINVAL; 414 415 return count; 416 } 417 static struct kobj_attribute defrag_attr = __ATTR_RW(defrag); 418 419 static ssize_t use_zero_page_show(struct kobject *kobj, 420 struct kobj_attribute *attr, char *buf) 421 { 422 return single_hugepage_flag_show(kobj, attr, buf, 423 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 424 } 425 static ssize_t use_zero_page_store(struct kobject *kobj, 426 struct kobj_attribute *attr, const char *buf, size_t count) 427 { 428 return single_hugepage_flag_store(kobj, attr, buf, count, 429 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 430 } 431 static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page); 432 433 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 434 struct kobj_attribute *attr, char *buf) 435 { 436 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); 437 } 438 static struct kobj_attribute hpage_pmd_size_attr = 439 __ATTR_RO(hpage_pmd_size); 440 441 static struct attribute *hugepage_attr[] = { 442 &enabled_attr.attr, 443 &defrag_attr.attr, 444 &use_zero_page_attr.attr, 445 &hpage_pmd_size_attr.attr, 446 #ifdef CONFIG_SHMEM 447 &shmem_enabled_attr.attr, 448 #endif 449 NULL, 450 }; 451 452 static const struct attribute_group hugepage_attr_group = { 453 .attrs = hugepage_attr, 454 }; 455 456 static void hugepage_exit_sysfs(struct kobject *hugepage_kobj); 457 static void thpsize_release(struct kobject *kobj); 458 static DEFINE_SPINLOCK(huge_anon_orders_lock); 459 static LIST_HEAD(thpsize_list); 460 461 static ssize_t thpsize_enabled_show(struct kobject *kobj, 462 struct kobj_attribute *attr, char *buf) 463 { 464 int order = to_thpsize(kobj)->order; 465 const char *output; 466 467 if (test_bit(order, &huge_anon_orders_always)) 468 output = "[always] inherit madvise never"; 469 else if (test_bit(order, &huge_anon_orders_inherit)) 470 output = "always [inherit] madvise never"; 471 else if (test_bit(order, &huge_anon_orders_madvise)) 472 output = "always inherit [madvise] never"; 473 else 474 output = "always inherit madvise [never]"; 475 476 return sysfs_emit(buf, "%s\n", output); 477 } 478 479 static ssize_t thpsize_enabled_store(struct kobject *kobj, 480 struct kobj_attribute *attr, 481 const char *buf, size_t count) 482 { 483 int order = to_thpsize(kobj)->order; 484 ssize_t ret = count; 485 486 if (sysfs_streq(buf, "always")) { 487 spin_lock(&huge_anon_orders_lock); 488 clear_bit(order, &huge_anon_orders_inherit); 489 clear_bit(order, &huge_anon_orders_madvise); 490 set_bit(order, &huge_anon_orders_always); 491 spin_unlock(&huge_anon_orders_lock); 492 } else if (sysfs_streq(buf, "inherit")) { 493 spin_lock(&huge_anon_orders_lock); 494 clear_bit(order, &huge_anon_orders_always); 495 clear_bit(order, &huge_anon_orders_madvise); 496 set_bit(order, &huge_anon_orders_inherit); 497 spin_unlock(&huge_anon_orders_lock); 498 } else if (sysfs_streq(buf, "madvise")) { 499 spin_lock(&huge_anon_orders_lock); 500 clear_bit(order, &huge_anon_orders_always); 501 clear_bit(order, &huge_anon_orders_inherit); 502 set_bit(order, &huge_anon_orders_madvise); 503 spin_unlock(&huge_anon_orders_lock); 504 } else if (sysfs_streq(buf, "never")) { 505 spin_lock(&huge_anon_orders_lock); 506 clear_bit(order, &huge_anon_orders_always); 507 clear_bit(order, &huge_anon_orders_inherit); 508 clear_bit(order, &huge_anon_orders_madvise); 509 spin_unlock(&huge_anon_orders_lock); 510 } else 511 ret = -EINVAL; 512 513 if (ret > 0) { 514 int err; 515 516 err = start_stop_khugepaged(); 517 if (err) 518 ret = err; 519 } 520 return ret; 521 } 522 523 static struct kobj_attribute thpsize_enabled_attr = 524 __ATTR(enabled, 0644, thpsize_enabled_show, thpsize_enabled_store); 525 526 static struct attribute *thpsize_attrs[] = { 527 &thpsize_enabled_attr.attr, 528 #ifdef CONFIG_SHMEM 529 &thpsize_shmem_enabled_attr.attr, 530 #endif 531 NULL, 532 }; 533 534 static const struct attribute_group thpsize_attr_group = { 535 .attrs = thpsize_attrs, 536 }; 537 538 static const struct kobj_type thpsize_ktype = { 539 .release = &thpsize_release, 540 .sysfs_ops = &kobj_sysfs_ops, 541 }; 542 543 DEFINE_PER_CPU(struct mthp_stat, mthp_stats) = {{{0}}}; 544 545 static unsigned long sum_mthp_stat(int order, enum mthp_stat_item item) 546 { 547 unsigned long sum = 0; 548 int cpu; 549 550 for_each_possible_cpu(cpu) { 551 struct mthp_stat *this = &per_cpu(mthp_stats, cpu); 552 553 sum += this->stats[order][item]; 554 } 555 556 return sum; 557 } 558 559 #define DEFINE_MTHP_STAT_ATTR(_name, _index) \ 560 static ssize_t _name##_show(struct kobject *kobj, \ 561 struct kobj_attribute *attr, char *buf) \ 562 { \ 563 int order = to_thpsize(kobj)->order; \ 564 \ 565 return sysfs_emit(buf, "%lu\n", sum_mthp_stat(order, _index)); \ 566 } \ 567 static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 568 569 DEFINE_MTHP_STAT_ATTR(anon_fault_alloc, MTHP_STAT_ANON_FAULT_ALLOC); 570 DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK); 571 DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); 572 DEFINE_MTHP_STAT_ATTR(swpout, MTHP_STAT_SWPOUT); 573 DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK); 574 DEFINE_MTHP_STAT_ATTR(shmem_alloc, MTHP_STAT_SHMEM_ALLOC); 575 DEFINE_MTHP_STAT_ATTR(shmem_fallback, MTHP_STAT_SHMEM_FALLBACK); 576 DEFINE_MTHP_STAT_ATTR(shmem_fallback_charge, MTHP_STAT_SHMEM_FALLBACK_CHARGE); 577 DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT); 578 DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED); 579 DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED); 580 581 static struct attribute *stats_attrs[] = { 582 &anon_fault_alloc_attr.attr, 583 &anon_fault_fallback_attr.attr, 584 &anon_fault_fallback_charge_attr.attr, 585 &swpout_attr.attr, 586 &swpout_fallback_attr.attr, 587 &shmem_alloc_attr.attr, 588 &shmem_fallback_attr.attr, 589 &shmem_fallback_charge_attr.attr, 590 &split_attr.attr, 591 &split_failed_attr.attr, 592 &split_deferred_attr.attr, 593 NULL, 594 }; 595 596 static struct attribute_group stats_attr_group = { 597 .name = "stats", 598 .attrs = stats_attrs, 599 }; 600 601 static struct thpsize *thpsize_create(int order, struct kobject *parent) 602 { 603 unsigned long size = (PAGE_SIZE << order) / SZ_1K; 604 struct thpsize *thpsize; 605 int ret; 606 607 thpsize = kzalloc(sizeof(*thpsize), GFP_KERNEL); 608 if (!thpsize) 609 return ERR_PTR(-ENOMEM); 610 611 ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent, 612 "hugepages-%lukB", size); 613 if (ret) { 614 kfree(thpsize); 615 return ERR_PTR(ret); 616 } 617 618 ret = sysfs_create_group(&thpsize->kobj, &thpsize_attr_group); 619 if (ret) { 620 kobject_put(&thpsize->kobj); 621 return ERR_PTR(ret); 622 } 623 624 ret = sysfs_create_group(&thpsize->kobj, &stats_attr_group); 625 if (ret) { 626 kobject_put(&thpsize->kobj); 627 return ERR_PTR(ret); 628 } 629 630 thpsize->order = order; 631 return thpsize; 632 } 633 634 static void thpsize_release(struct kobject *kobj) 635 { 636 kfree(to_thpsize(kobj)); 637 } 638 639 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 640 { 641 int err; 642 struct thpsize *thpsize; 643 unsigned long orders; 644 int order; 645 646 /* 647 * Default to setting PMD-sized THP to inherit the global setting and 648 * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time 649 * constant so we have to do this here. 650 */ 651 huge_anon_orders_inherit = BIT(PMD_ORDER); 652 653 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 654 if (unlikely(!*hugepage_kobj)) { 655 pr_err("failed to create transparent hugepage kobject\n"); 656 return -ENOMEM; 657 } 658 659 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 660 if (err) { 661 pr_err("failed to register transparent hugepage group\n"); 662 goto delete_obj; 663 } 664 665 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 666 if (err) { 667 pr_err("failed to register transparent hugepage group\n"); 668 goto remove_hp_group; 669 } 670 671 orders = THP_ORDERS_ALL_ANON; 672 order = highest_order(orders); 673 while (orders) { 674 thpsize = thpsize_create(order, *hugepage_kobj); 675 if (IS_ERR(thpsize)) { 676 pr_err("failed to create thpsize for order %d\n", order); 677 err = PTR_ERR(thpsize); 678 goto remove_all; 679 } 680 list_add(&thpsize->node, &thpsize_list); 681 order = next_order(&orders, order); 682 } 683 684 return 0; 685 686 remove_all: 687 hugepage_exit_sysfs(*hugepage_kobj); 688 return err; 689 remove_hp_group: 690 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 691 delete_obj: 692 kobject_put(*hugepage_kobj); 693 return err; 694 } 695 696 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 697 { 698 struct thpsize *thpsize, *tmp; 699 700 list_for_each_entry_safe(thpsize, tmp, &thpsize_list, node) { 701 list_del(&thpsize->node); 702 kobject_put(&thpsize->kobj); 703 } 704 705 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 706 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 707 kobject_put(hugepage_kobj); 708 } 709 #else 710 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 711 { 712 return 0; 713 } 714 715 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 716 { 717 } 718 #endif /* CONFIG_SYSFS */ 719 720 static int __init thp_shrinker_init(void) 721 { 722 huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero"); 723 if (!huge_zero_page_shrinker) 724 return -ENOMEM; 725 726 deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE | 727 SHRINKER_MEMCG_AWARE | 728 SHRINKER_NONSLAB, 729 "thp-deferred_split"); 730 if (!deferred_split_shrinker) { 731 shrinker_free(huge_zero_page_shrinker); 732 return -ENOMEM; 733 } 734 735 huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count; 736 huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan; 737 shrinker_register(huge_zero_page_shrinker); 738 739 deferred_split_shrinker->count_objects = deferred_split_count; 740 deferred_split_shrinker->scan_objects = deferred_split_scan; 741 shrinker_register(deferred_split_shrinker); 742 743 return 0; 744 } 745 746 static void __init thp_shrinker_exit(void) 747 { 748 shrinker_free(huge_zero_page_shrinker); 749 shrinker_free(deferred_split_shrinker); 750 } 751 752 static int __init hugepage_init(void) 753 { 754 int err; 755 struct kobject *hugepage_kobj; 756 757 if (!has_transparent_hugepage()) { 758 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED; 759 return -EINVAL; 760 } 761 762 /* 763 * hugepages can't be allocated by the buddy allocator 764 */ 765 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER > MAX_PAGE_ORDER); 766 767 err = hugepage_init_sysfs(&hugepage_kobj); 768 if (err) 769 goto err_sysfs; 770 771 err = khugepaged_init(); 772 if (err) 773 goto err_slab; 774 775 err = thp_shrinker_init(); 776 if (err) 777 goto err_shrinker; 778 779 /* 780 * By default disable transparent hugepages on smaller systems, 781 * where the extra memory used could hurt more than TLB overhead 782 * is likely to save. The admin can still enable it through /sys. 783 */ 784 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 785 transparent_hugepage_flags = 0; 786 return 0; 787 } 788 789 err = start_stop_khugepaged(); 790 if (err) 791 goto err_khugepaged; 792 793 return 0; 794 err_khugepaged: 795 thp_shrinker_exit(); 796 err_shrinker: 797 khugepaged_destroy(); 798 err_slab: 799 hugepage_exit_sysfs(hugepage_kobj); 800 err_sysfs: 801 return err; 802 } 803 subsys_initcall(hugepage_init); 804 805 static int __init setup_transparent_hugepage(char *str) 806 { 807 int ret = 0; 808 if (!str) 809 goto out; 810 if (!strcmp(str, "always")) { 811 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 812 &transparent_hugepage_flags); 813 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 814 &transparent_hugepage_flags); 815 ret = 1; 816 } else if (!strcmp(str, "madvise")) { 817 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 818 &transparent_hugepage_flags); 819 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 820 &transparent_hugepage_flags); 821 ret = 1; 822 } else if (!strcmp(str, "never")) { 823 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 824 &transparent_hugepage_flags); 825 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 826 &transparent_hugepage_flags); 827 ret = 1; 828 } 829 out: 830 if (!ret) 831 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 832 return ret; 833 } 834 __setup("transparent_hugepage=", setup_transparent_hugepage); 835 836 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 837 { 838 if (likely(vma->vm_flags & VM_WRITE)) 839 pmd = pmd_mkwrite(pmd, vma); 840 return pmd; 841 } 842 843 #ifdef CONFIG_MEMCG 844 static inline 845 struct deferred_split *get_deferred_split_queue(struct folio *folio) 846 { 847 struct mem_cgroup *memcg = folio_memcg(folio); 848 struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); 849 850 if (memcg) 851 return &memcg->deferred_split_queue; 852 else 853 return &pgdat->deferred_split_queue; 854 } 855 #else 856 static inline 857 struct deferred_split *get_deferred_split_queue(struct folio *folio) 858 { 859 struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); 860 861 return &pgdat->deferred_split_queue; 862 } 863 #endif 864 865 static inline bool is_transparent_hugepage(const struct folio *folio) 866 { 867 if (!folio_test_large(folio)) 868 return false; 869 870 return is_huge_zero_folio(folio) || 871 folio_test_large_rmappable(folio); 872 } 873 874 static unsigned long __thp_get_unmapped_area(struct file *filp, 875 unsigned long addr, unsigned long len, 876 loff_t off, unsigned long flags, unsigned long size, 877 vm_flags_t vm_flags) 878 { 879 loff_t off_end = off + len; 880 loff_t off_align = round_up(off, size); 881 unsigned long len_pad, ret, off_sub; 882 883 if (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()) 884 return 0; 885 886 if (off_end <= off_align || (off_end - off_align) < size) 887 return 0; 888 889 len_pad = len + size; 890 if (len_pad < len || (off + len_pad) < off) 891 return 0; 892 893 ret = mm_get_unmapped_area_vmflags(current->mm, filp, addr, len_pad, 894 off >> PAGE_SHIFT, flags, vm_flags); 895 896 /* 897 * The failure might be due to length padding. The caller will retry 898 * without the padding. 899 */ 900 if (IS_ERR_VALUE(ret)) 901 return 0; 902 903 /* 904 * Do not try to align to THP boundary if allocation at the address 905 * hint succeeds. 906 */ 907 if (ret == addr) 908 return addr; 909 910 off_sub = (off - ret) & (size - 1); 911 912 if (test_bit(MMF_TOPDOWN, ¤t->mm->flags) && !off_sub) 913 return ret + size; 914 915 ret += off_sub; 916 return ret; 917 } 918 919 unsigned long thp_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, 920 unsigned long len, unsigned long pgoff, unsigned long flags, 921 vm_flags_t vm_flags) 922 { 923 unsigned long ret; 924 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 925 926 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE, vm_flags); 927 if (ret) 928 return ret; 929 930 return mm_get_unmapped_area_vmflags(current->mm, filp, addr, len, pgoff, flags, 931 vm_flags); 932 } 933 934 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 935 unsigned long len, unsigned long pgoff, unsigned long flags) 936 { 937 return thp_get_unmapped_area_vmflags(filp, addr, len, pgoff, flags, 0); 938 } 939 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 940 941 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 942 struct page *page, gfp_t gfp) 943 { 944 struct vm_area_struct *vma = vmf->vma; 945 struct folio *folio = page_folio(page); 946 pgtable_t pgtable; 947 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 948 vm_fault_t ret = 0; 949 950 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 951 952 if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) { 953 folio_put(folio); 954 count_vm_event(THP_FAULT_FALLBACK); 955 count_vm_event(THP_FAULT_FALLBACK_CHARGE); 956 count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK); 957 count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE); 958 return VM_FAULT_FALLBACK; 959 } 960 folio_throttle_swaprate(folio, gfp); 961 962 pgtable = pte_alloc_one(vma->vm_mm); 963 if (unlikely(!pgtable)) { 964 ret = VM_FAULT_OOM; 965 goto release; 966 } 967 968 folio_zero_user(folio, vmf->address); 969 /* 970 * The memory barrier inside __folio_mark_uptodate makes sure that 971 * folio_zero_user writes become visible before the set_pmd_at() 972 * write. 973 */ 974 __folio_mark_uptodate(folio); 975 976 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 977 if (unlikely(!pmd_none(*vmf->pmd))) { 978 goto unlock_release; 979 } else { 980 pmd_t entry; 981 982 ret = check_stable_address_space(vma->vm_mm); 983 if (ret) 984 goto unlock_release; 985 986 /* Deliver the page fault to userland */ 987 if (userfaultfd_missing(vma)) { 988 spin_unlock(vmf->ptl); 989 folio_put(folio); 990 pte_free(vma->vm_mm, pgtable); 991 ret = handle_userfault(vmf, VM_UFFD_MISSING); 992 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 993 return ret; 994 } 995 996 entry = mk_huge_pmd(page, vma->vm_page_prot); 997 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 998 folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE); 999 folio_add_lru_vma(folio, vma); 1000 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 1001 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 1002 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1003 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1004 mm_inc_nr_ptes(vma->vm_mm); 1005 spin_unlock(vmf->ptl); 1006 count_vm_event(THP_FAULT_ALLOC); 1007 count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC); 1008 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); 1009 } 1010 1011 return 0; 1012 unlock_release: 1013 spin_unlock(vmf->ptl); 1014 release: 1015 if (pgtable) 1016 pte_free(vma->vm_mm, pgtable); 1017 folio_put(folio); 1018 return ret; 1019 1020 } 1021 1022 /* 1023 * always: directly stall for all thp allocations 1024 * defer: wake kswapd and fail if not immediately available 1025 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 1026 * fail if not immediately available 1027 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 1028 * available 1029 * never: never stall for any thp allocation 1030 */ 1031 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) 1032 { 1033 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); 1034 1035 /* Always do synchronous compaction */ 1036 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 1037 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 1038 1039 /* Kick kcompactd and fail quickly */ 1040 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 1041 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; 1042 1043 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 1044 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 1045 return GFP_TRANSHUGE_LIGHT | 1046 (vma_madvised ? __GFP_DIRECT_RECLAIM : 1047 __GFP_KSWAPD_RECLAIM); 1048 1049 /* Only do synchronous compaction if madvised */ 1050 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 1051 return GFP_TRANSHUGE_LIGHT | 1052 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 1053 1054 return GFP_TRANSHUGE_LIGHT; 1055 } 1056 1057 /* Caller must hold page table lock. */ 1058 static void set_huge_zero_folio(pgtable_t pgtable, struct mm_struct *mm, 1059 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 1060 struct folio *zero_folio) 1061 { 1062 pmd_t entry; 1063 if (!pmd_none(*pmd)) 1064 return; 1065 entry = mk_pmd(&zero_folio->page, vma->vm_page_prot); 1066 entry = pmd_mkhuge(entry); 1067 pgtable_trans_huge_deposit(mm, pmd, pgtable); 1068 set_pmd_at(mm, haddr, pmd, entry); 1069 mm_inc_nr_ptes(mm); 1070 } 1071 1072 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 1073 { 1074 struct vm_area_struct *vma = vmf->vma; 1075 gfp_t gfp; 1076 struct folio *folio; 1077 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1078 vm_fault_t ret; 1079 1080 if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER)) 1081 return VM_FAULT_FALLBACK; 1082 ret = vmf_anon_prepare(vmf); 1083 if (ret) 1084 return ret; 1085 khugepaged_enter_vma(vma, vma->vm_flags); 1086 1087 if (!(vmf->flags & FAULT_FLAG_WRITE) && 1088 !mm_forbids_zeropage(vma->vm_mm) && 1089 transparent_hugepage_use_zero_page()) { 1090 pgtable_t pgtable; 1091 struct folio *zero_folio; 1092 vm_fault_t ret; 1093 1094 pgtable = pte_alloc_one(vma->vm_mm); 1095 if (unlikely(!pgtable)) 1096 return VM_FAULT_OOM; 1097 zero_folio = mm_get_huge_zero_folio(vma->vm_mm); 1098 if (unlikely(!zero_folio)) { 1099 pte_free(vma->vm_mm, pgtable); 1100 count_vm_event(THP_FAULT_FALLBACK); 1101 return VM_FAULT_FALLBACK; 1102 } 1103 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1104 ret = 0; 1105 if (pmd_none(*vmf->pmd)) { 1106 ret = check_stable_address_space(vma->vm_mm); 1107 if (ret) { 1108 spin_unlock(vmf->ptl); 1109 pte_free(vma->vm_mm, pgtable); 1110 } else if (userfaultfd_missing(vma)) { 1111 spin_unlock(vmf->ptl); 1112 pte_free(vma->vm_mm, pgtable); 1113 ret = handle_userfault(vmf, VM_UFFD_MISSING); 1114 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 1115 } else { 1116 set_huge_zero_folio(pgtable, vma->vm_mm, vma, 1117 haddr, vmf->pmd, zero_folio); 1118 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1119 spin_unlock(vmf->ptl); 1120 } 1121 } else { 1122 spin_unlock(vmf->ptl); 1123 pte_free(vma->vm_mm, pgtable); 1124 } 1125 return ret; 1126 } 1127 gfp = vma_thp_gfp_mask(vma); 1128 folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true); 1129 if (unlikely(!folio)) { 1130 count_vm_event(THP_FAULT_FALLBACK); 1131 count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_FALLBACK); 1132 return VM_FAULT_FALLBACK; 1133 } 1134 return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp); 1135 } 1136 1137 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 1138 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 1139 pgtable_t pgtable) 1140 { 1141 struct mm_struct *mm = vma->vm_mm; 1142 pmd_t entry; 1143 spinlock_t *ptl; 1144 1145 ptl = pmd_lock(mm, pmd); 1146 if (!pmd_none(*pmd)) { 1147 if (write) { 1148 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 1149 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 1150 goto out_unlock; 1151 } 1152 entry = pmd_mkyoung(*pmd); 1153 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1154 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 1155 update_mmu_cache_pmd(vma, addr, pmd); 1156 } 1157 1158 goto out_unlock; 1159 } 1160 1161 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 1162 if (pfn_t_devmap(pfn)) 1163 entry = pmd_mkdevmap(entry); 1164 if (write) { 1165 entry = pmd_mkyoung(pmd_mkdirty(entry)); 1166 entry = maybe_pmd_mkwrite(entry, vma); 1167 } 1168 1169 if (pgtable) { 1170 pgtable_trans_huge_deposit(mm, pmd, pgtable); 1171 mm_inc_nr_ptes(mm); 1172 pgtable = NULL; 1173 } 1174 1175 set_pmd_at(mm, addr, pmd, entry); 1176 update_mmu_cache_pmd(vma, addr, pmd); 1177 1178 out_unlock: 1179 spin_unlock(ptl); 1180 if (pgtable) 1181 pte_free(mm, pgtable); 1182 } 1183 1184 /** 1185 * vmf_insert_pfn_pmd - insert a pmd size pfn 1186 * @vmf: Structure describing the fault 1187 * @pfn: pfn to insert 1188 * @write: whether it's a write fault 1189 * 1190 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info. 1191 * 1192 * Return: vm_fault_t value. 1193 */ 1194 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) 1195 { 1196 unsigned long addr = vmf->address & PMD_MASK; 1197 struct vm_area_struct *vma = vmf->vma; 1198 pgprot_t pgprot = vma->vm_page_prot; 1199 pgtable_t pgtable = NULL; 1200 1201 /* 1202 * If we had pmd_special, we could avoid all these restrictions, 1203 * but we need to be consistent with PTEs and architectures that 1204 * can't support a 'special' bit. 1205 */ 1206 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 1207 !pfn_t_devmap(pfn)); 1208 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1209 (VM_PFNMAP|VM_MIXEDMAP)); 1210 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1211 1212 if (addr < vma->vm_start || addr >= vma->vm_end) 1213 return VM_FAULT_SIGBUS; 1214 1215 if (arch_needs_pgtable_deposit()) { 1216 pgtable = pte_alloc_one(vma->vm_mm); 1217 if (!pgtable) 1218 return VM_FAULT_OOM; 1219 } 1220 1221 track_pfn_insert(vma, &pgprot, pfn); 1222 1223 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 1224 return VM_FAULT_NOPAGE; 1225 } 1226 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); 1227 1228 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1229 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 1230 { 1231 if (likely(vma->vm_flags & VM_WRITE)) 1232 pud = pud_mkwrite(pud); 1233 return pud; 1234 } 1235 1236 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 1237 pud_t *pud, pfn_t pfn, bool write) 1238 { 1239 struct mm_struct *mm = vma->vm_mm; 1240 pgprot_t prot = vma->vm_page_prot; 1241 pud_t entry; 1242 spinlock_t *ptl; 1243 1244 ptl = pud_lock(mm, pud); 1245 if (!pud_none(*pud)) { 1246 if (write) { 1247 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 1248 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 1249 goto out_unlock; 1250 } 1251 entry = pud_mkyoung(*pud); 1252 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 1253 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 1254 update_mmu_cache_pud(vma, addr, pud); 1255 } 1256 goto out_unlock; 1257 } 1258 1259 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 1260 if (pfn_t_devmap(pfn)) 1261 entry = pud_mkdevmap(entry); 1262 if (write) { 1263 entry = pud_mkyoung(pud_mkdirty(entry)); 1264 entry = maybe_pud_mkwrite(entry, vma); 1265 } 1266 set_pud_at(mm, addr, pud, entry); 1267 update_mmu_cache_pud(vma, addr, pud); 1268 1269 out_unlock: 1270 spin_unlock(ptl); 1271 } 1272 1273 /** 1274 * vmf_insert_pfn_pud - insert a pud size pfn 1275 * @vmf: Structure describing the fault 1276 * @pfn: pfn to insert 1277 * @write: whether it's a write fault 1278 * 1279 * Insert a pud size pfn. See vmf_insert_pfn() for additional info. 1280 * 1281 * Return: vm_fault_t value. 1282 */ 1283 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) 1284 { 1285 unsigned long addr = vmf->address & PUD_MASK; 1286 struct vm_area_struct *vma = vmf->vma; 1287 pgprot_t pgprot = vma->vm_page_prot; 1288 1289 /* 1290 * If we had pud_special, we could avoid all these restrictions, 1291 * but we need to be consistent with PTEs and architectures that 1292 * can't support a 'special' bit. 1293 */ 1294 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 1295 !pfn_t_devmap(pfn)); 1296 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1297 (VM_PFNMAP|VM_MIXEDMAP)); 1298 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1299 1300 if (addr < vma->vm_start || addr >= vma->vm_end) 1301 return VM_FAULT_SIGBUS; 1302 1303 track_pfn_insert(vma, &pgprot, pfn); 1304 1305 insert_pfn_pud(vma, addr, vmf->pud, pfn, write); 1306 return VM_FAULT_NOPAGE; 1307 } 1308 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); 1309 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1310 1311 void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 1312 pmd_t *pmd, bool write) 1313 { 1314 pmd_t _pmd; 1315 1316 _pmd = pmd_mkyoung(*pmd); 1317 if (write) 1318 _pmd = pmd_mkdirty(_pmd); 1319 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 1320 pmd, _pmd, write)) 1321 update_mmu_cache_pmd(vma, addr, pmd); 1322 } 1323 1324 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 1325 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 1326 { 1327 unsigned long pfn = pmd_pfn(*pmd); 1328 struct mm_struct *mm = vma->vm_mm; 1329 struct page *page; 1330 int ret; 1331 1332 assert_spin_locked(pmd_lockptr(mm, pmd)); 1333 1334 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 1335 return NULL; 1336 1337 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 1338 /* pass */; 1339 else 1340 return NULL; 1341 1342 if (flags & FOLL_TOUCH) 1343 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1344 1345 /* 1346 * device mapped pages can only be returned if the 1347 * caller will manage the page reference count. 1348 */ 1349 if (!(flags & (FOLL_GET | FOLL_PIN))) 1350 return ERR_PTR(-EEXIST); 1351 1352 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 1353 *pgmap = get_dev_pagemap(pfn, *pgmap); 1354 if (!*pgmap) 1355 return ERR_PTR(-EFAULT); 1356 page = pfn_to_page(pfn); 1357 ret = try_grab_folio(page_folio(page), 1, flags); 1358 if (ret) 1359 page = ERR_PTR(ret); 1360 1361 return page; 1362 } 1363 1364 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1365 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1366 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) 1367 { 1368 spinlock_t *dst_ptl, *src_ptl; 1369 struct page *src_page; 1370 struct folio *src_folio; 1371 pmd_t pmd; 1372 pgtable_t pgtable = NULL; 1373 int ret = -ENOMEM; 1374 1375 /* Skip if can be re-fill on fault */ 1376 if (!vma_is_anonymous(dst_vma)) 1377 return 0; 1378 1379 pgtable = pte_alloc_one(dst_mm); 1380 if (unlikely(!pgtable)) 1381 goto out; 1382 1383 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1384 src_ptl = pmd_lockptr(src_mm, src_pmd); 1385 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1386 1387 ret = -EAGAIN; 1388 pmd = *src_pmd; 1389 1390 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1391 if (unlikely(is_swap_pmd(pmd))) { 1392 swp_entry_t entry = pmd_to_swp_entry(pmd); 1393 1394 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1395 if (!is_readable_migration_entry(entry)) { 1396 entry = make_readable_migration_entry( 1397 swp_offset(entry)); 1398 pmd = swp_entry_to_pmd(entry); 1399 if (pmd_swp_soft_dirty(*src_pmd)) 1400 pmd = pmd_swp_mksoft_dirty(pmd); 1401 if (pmd_swp_uffd_wp(*src_pmd)) 1402 pmd = pmd_swp_mkuffd_wp(pmd); 1403 set_pmd_at(src_mm, addr, src_pmd, pmd); 1404 } 1405 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1406 mm_inc_nr_ptes(dst_mm); 1407 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1408 if (!userfaultfd_wp(dst_vma)) 1409 pmd = pmd_swp_clear_uffd_wp(pmd); 1410 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1411 ret = 0; 1412 goto out_unlock; 1413 } 1414 #endif 1415 1416 if (unlikely(!pmd_trans_huge(pmd))) { 1417 pte_free(dst_mm, pgtable); 1418 goto out_unlock; 1419 } 1420 /* 1421 * When page table lock is held, the huge zero pmd should not be 1422 * under splitting since we don't split the page itself, only pmd to 1423 * a page table. 1424 */ 1425 if (is_huge_zero_pmd(pmd)) { 1426 /* 1427 * mm_get_huge_zero_folio() will never allocate a new 1428 * folio here, since we already have a zero page to 1429 * copy. It just takes a reference. 1430 */ 1431 mm_get_huge_zero_folio(dst_mm); 1432 goto out_zero_page; 1433 } 1434 1435 src_page = pmd_page(pmd); 1436 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1437 src_folio = page_folio(src_page); 1438 1439 folio_get(src_folio); 1440 if (unlikely(folio_try_dup_anon_rmap_pmd(src_folio, src_page, src_vma))) { 1441 /* Page maybe pinned: split and retry the fault on PTEs. */ 1442 folio_put(src_folio); 1443 pte_free(dst_mm, pgtable); 1444 spin_unlock(src_ptl); 1445 spin_unlock(dst_ptl); 1446 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); 1447 return -EAGAIN; 1448 } 1449 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1450 out_zero_page: 1451 mm_inc_nr_ptes(dst_mm); 1452 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1453 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1454 if (!userfaultfd_wp(dst_vma)) 1455 pmd = pmd_clear_uffd_wp(pmd); 1456 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1457 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1458 1459 ret = 0; 1460 out_unlock: 1461 spin_unlock(src_ptl); 1462 spin_unlock(dst_ptl); 1463 out: 1464 return ret; 1465 } 1466 1467 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1468 void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1469 pud_t *pud, bool write) 1470 { 1471 pud_t _pud; 1472 1473 _pud = pud_mkyoung(*pud); 1474 if (write) 1475 _pud = pud_mkdirty(_pud); 1476 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1477 pud, _pud, write)) 1478 update_mmu_cache_pud(vma, addr, pud); 1479 } 1480 1481 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1482 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1483 struct vm_area_struct *vma) 1484 { 1485 spinlock_t *dst_ptl, *src_ptl; 1486 pud_t pud; 1487 int ret; 1488 1489 dst_ptl = pud_lock(dst_mm, dst_pud); 1490 src_ptl = pud_lockptr(src_mm, src_pud); 1491 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1492 1493 ret = -EAGAIN; 1494 pud = *src_pud; 1495 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1496 goto out_unlock; 1497 1498 /* 1499 * When page table lock is held, the huge zero pud should not be 1500 * under splitting since we don't split the page itself, only pud to 1501 * a page table. 1502 */ 1503 if (is_huge_zero_pud(pud)) { 1504 /* No huge zero pud yet */ 1505 } 1506 1507 /* 1508 * TODO: once we support anonymous pages, use 1509 * folio_try_dup_anon_rmap_*() and split if duplicating fails. 1510 */ 1511 pudp_set_wrprotect(src_mm, addr, src_pud); 1512 pud = pud_mkold(pud_wrprotect(pud)); 1513 set_pud_at(dst_mm, addr, dst_pud, pud); 1514 1515 ret = 0; 1516 out_unlock: 1517 spin_unlock(src_ptl); 1518 spin_unlock(dst_ptl); 1519 return ret; 1520 } 1521 1522 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1523 { 1524 bool write = vmf->flags & FAULT_FLAG_WRITE; 1525 1526 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1527 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1528 goto unlock; 1529 1530 touch_pud(vmf->vma, vmf->address, vmf->pud, write); 1531 unlock: 1532 spin_unlock(vmf->ptl); 1533 } 1534 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1535 1536 void huge_pmd_set_accessed(struct vm_fault *vmf) 1537 { 1538 bool write = vmf->flags & FAULT_FLAG_WRITE; 1539 1540 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1541 if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) 1542 goto unlock; 1543 1544 touch_pmd(vmf->vma, vmf->address, vmf->pmd, write); 1545 1546 unlock: 1547 spin_unlock(vmf->ptl); 1548 } 1549 1550 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) 1551 { 1552 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; 1553 struct vm_area_struct *vma = vmf->vma; 1554 struct folio *folio; 1555 struct page *page; 1556 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1557 pmd_t orig_pmd = vmf->orig_pmd; 1558 1559 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1560 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1561 1562 if (is_huge_zero_pmd(orig_pmd)) 1563 goto fallback; 1564 1565 spin_lock(vmf->ptl); 1566 1567 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1568 spin_unlock(vmf->ptl); 1569 return 0; 1570 } 1571 1572 page = pmd_page(orig_pmd); 1573 folio = page_folio(page); 1574 VM_BUG_ON_PAGE(!PageHead(page), page); 1575 1576 /* Early check when only holding the PT lock. */ 1577 if (PageAnonExclusive(page)) 1578 goto reuse; 1579 1580 if (!folio_trylock(folio)) { 1581 folio_get(folio); 1582 spin_unlock(vmf->ptl); 1583 folio_lock(folio); 1584 spin_lock(vmf->ptl); 1585 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1586 spin_unlock(vmf->ptl); 1587 folio_unlock(folio); 1588 folio_put(folio); 1589 return 0; 1590 } 1591 folio_put(folio); 1592 } 1593 1594 /* Recheck after temporarily dropping the PT lock. */ 1595 if (PageAnonExclusive(page)) { 1596 folio_unlock(folio); 1597 goto reuse; 1598 } 1599 1600 /* 1601 * See do_wp_page(): we can only reuse the folio exclusively if 1602 * there are no additional references. Note that we always drain 1603 * the LRU cache immediately after adding a THP. 1604 */ 1605 if (folio_ref_count(folio) > 1606 1 + folio_test_swapcache(folio) * folio_nr_pages(folio)) 1607 goto unlock_fallback; 1608 if (folio_test_swapcache(folio)) 1609 folio_free_swap(folio); 1610 if (folio_ref_count(folio) == 1) { 1611 pmd_t entry; 1612 1613 folio_move_anon_rmap(folio, vma); 1614 SetPageAnonExclusive(page); 1615 folio_unlock(folio); 1616 reuse: 1617 if (unlikely(unshare)) { 1618 spin_unlock(vmf->ptl); 1619 return 0; 1620 } 1621 entry = pmd_mkyoung(orig_pmd); 1622 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1623 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1624 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1625 spin_unlock(vmf->ptl); 1626 return 0; 1627 } 1628 1629 unlock_fallback: 1630 folio_unlock(folio); 1631 spin_unlock(vmf->ptl); 1632 fallback: 1633 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1634 return VM_FAULT_FALLBACK; 1635 } 1636 1637 static inline bool can_change_pmd_writable(struct vm_area_struct *vma, 1638 unsigned long addr, pmd_t pmd) 1639 { 1640 struct page *page; 1641 1642 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) 1643 return false; 1644 1645 /* Don't touch entries that are not even readable (NUMA hinting). */ 1646 if (pmd_protnone(pmd)) 1647 return false; 1648 1649 /* Do we need write faults for softdirty tracking? */ 1650 if (pmd_needs_soft_dirty_wp(vma, pmd)) 1651 return false; 1652 1653 /* Do we need write faults for uffd-wp tracking? */ 1654 if (userfaultfd_huge_pmd_wp(vma, pmd)) 1655 return false; 1656 1657 if (!(vma->vm_flags & VM_SHARED)) { 1658 /* See can_change_pte_writable(). */ 1659 page = vm_normal_page_pmd(vma, addr, pmd); 1660 return page && PageAnon(page) && PageAnonExclusive(page); 1661 } 1662 1663 /* See can_change_pte_writable(). */ 1664 return pmd_dirty(pmd); 1665 } 1666 1667 /* NUMA hinting page fault entry point for trans huge pmds */ 1668 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) 1669 { 1670 struct vm_area_struct *vma = vmf->vma; 1671 pmd_t oldpmd = vmf->orig_pmd; 1672 pmd_t pmd; 1673 struct folio *folio; 1674 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1675 int nid = NUMA_NO_NODE; 1676 int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK); 1677 bool writable = false; 1678 int flags = 0; 1679 1680 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1681 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1682 spin_unlock(vmf->ptl); 1683 return 0; 1684 } 1685 1686 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1687 1688 /* 1689 * Detect now whether the PMD could be writable; this information 1690 * is only valid while holding the PT lock. 1691 */ 1692 writable = pmd_write(pmd); 1693 if (!writable && vma_wants_manual_pte_write_upgrade(vma) && 1694 can_change_pmd_writable(vma, vmf->address, pmd)) 1695 writable = true; 1696 1697 folio = vm_normal_folio_pmd(vma, haddr, pmd); 1698 if (!folio) 1699 goto out_map; 1700 1701 /* See similar comment in do_numa_page for explanation */ 1702 if (!writable) 1703 flags |= TNF_NO_GROUP; 1704 1705 nid = folio_nid(folio); 1706 /* 1707 * For memory tiering mode, cpupid of slow memory page is used 1708 * to record page access time. So use default value. 1709 */ 1710 if (!folio_use_access_time(folio)) 1711 last_cpupid = folio_last_cpupid(folio); 1712 target_nid = numa_migrate_prep(folio, vmf, haddr, nid, &flags); 1713 if (target_nid == NUMA_NO_NODE) 1714 goto out_map; 1715 if (migrate_misplaced_folio_prepare(folio, vma, target_nid)) { 1716 flags |= TNF_MIGRATE_FAIL; 1717 goto out_map; 1718 } 1719 /* The folio is isolated and isolation code holds a folio reference. */ 1720 spin_unlock(vmf->ptl); 1721 writable = false; 1722 1723 if (!migrate_misplaced_folio(folio, vma, target_nid)) { 1724 flags |= TNF_MIGRATED; 1725 nid = target_nid; 1726 task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags); 1727 return 0; 1728 } 1729 1730 flags |= TNF_MIGRATE_FAIL; 1731 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1732 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1733 spin_unlock(vmf->ptl); 1734 return 0; 1735 } 1736 out_map: 1737 /* Restore the PMD */ 1738 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1739 pmd = pmd_mkyoung(pmd); 1740 if (writable) 1741 pmd = pmd_mkwrite(pmd, vma); 1742 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1743 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1744 spin_unlock(vmf->ptl); 1745 1746 if (nid != NUMA_NO_NODE) 1747 task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags); 1748 return 0; 1749 } 1750 1751 /* 1752 * Return true if we do MADV_FREE successfully on entire pmd page. 1753 * Otherwise, return false. 1754 */ 1755 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1756 pmd_t *pmd, unsigned long addr, unsigned long next) 1757 { 1758 spinlock_t *ptl; 1759 pmd_t orig_pmd; 1760 struct folio *folio; 1761 struct mm_struct *mm = tlb->mm; 1762 bool ret = false; 1763 1764 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1765 1766 ptl = pmd_trans_huge_lock(pmd, vma); 1767 if (!ptl) 1768 goto out_unlocked; 1769 1770 orig_pmd = *pmd; 1771 if (is_huge_zero_pmd(orig_pmd)) 1772 goto out; 1773 1774 if (unlikely(!pmd_present(orig_pmd))) { 1775 VM_BUG_ON(thp_migration_supported() && 1776 !is_pmd_migration_entry(orig_pmd)); 1777 goto out; 1778 } 1779 1780 folio = pmd_folio(orig_pmd); 1781 /* 1782 * If other processes are mapping this folio, we couldn't discard 1783 * the folio unless they all do MADV_FREE so let's skip the folio. 1784 */ 1785 if (folio_likely_mapped_shared(folio)) 1786 goto out; 1787 1788 if (!folio_trylock(folio)) 1789 goto out; 1790 1791 /* 1792 * If user want to discard part-pages of THP, split it so MADV_FREE 1793 * will deactivate only them. 1794 */ 1795 if (next - addr != HPAGE_PMD_SIZE) { 1796 folio_get(folio); 1797 spin_unlock(ptl); 1798 split_folio(folio); 1799 folio_unlock(folio); 1800 folio_put(folio); 1801 goto out_unlocked; 1802 } 1803 1804 if (folio_test_dirty(folio)) 1805 folio_clear_dirty(folio); 1806 folio_unlock(folio); 1807 1808 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1809 pmdp_invalidate(vma, addr, pmd); 1810 orig_pmd = pmd_mkold(orig_pmd); 1811 orig_pmd = pmd_mkclean(orig_pmd); 1812 1813 set_pmd_at(mm, addr, pmd, orig_pmd); 1814 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1815 } 1816 1817 folio_mark_lazyfree(folio); 1818 ret = true; 1819 out: 1820 spin_unlock(ptl); 1821 out_unlocked: 1822 return ret; 1823 } 1824 1825 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1826 { 1827 pgtable_t pgtable; 1828 1829 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1830 pte_free(mm, pgtable); 1831 mm_dec_nr_ptes(mm); 1832 } 1833 1834 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1835 pmd_t *pmd, unsigned long addr) 1836 { 1837 pmd_t orig_pmd; 1838 spinlock_t *ptl; 1839 1840 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1841 1842 ptl = __pmd_trans_huge_lock(pmd, vma); 1843 if (!ptl) 1844 return 0; 1845 /* 1846 * For architectures like ppc64 we look at deposited pgtable 1847 * when calling pmdp_huge_get_and_clear. So do the 1848 * pgtable_trans_huge_withdraw after finishing pmdp related 1849 * operations. 1850 */ 1851 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1852 tlb->fullmm); 1853 arch_check_zapped_pmd(vma, orig_pmd); 1854 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1855 if (vma_is_special_huge(vma)) { 1856 if (arch_needs_pgtable_deposit()) 1857 zap_deposited_table(tlb->mm, pmd); 1858 spin_unlock(ptl); 1859 } else if (is_huge_zero_pmd(orig_pmd)) { 1860 zap_deposited_table(tlb->mm, pmd); 1861 spin_unlock(ptl); 1862 } else { 1863 struct folio *folio = NULL; 1864 int flush_needed = 1; 1865 1866 if (pmd_present(orig_pmd)) { 1867 struct page *page = pmd_page(orig_pmd); 1868 1869 folio = page_folio(page); 1870 folio_remove_rmap_pmd(folio, page, vma); 1871 WARN_ON_ONCE(folio_mapcount(folio) < 0); 1872 VM_BUG_ON_PAGE(!PageHead(page), page); 1873 } else if (thp_migration_supported()) { 1874 swp_entry_t entry; 1875 1876 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1877 entry = pmd_to_swp_entry(orig_pmd); 1878 folio = pfn_swap_entry_folio(entry); 1879 flush_needed = 0; 1880 } else 1881 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1882 1883 if (folio_test_anon(folio)) { 1884 zap_deposited_table(tlb->mm, pmd); 1885 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1886 } else { 1887 if (arch_needs_pgtable_deposit()) 1888 zap_deposited_table(tlb->mm, pmd); 1889 add_mm_counter(tlb->mm, mm_counter_file(folio), 1890 -HPAGE_PMD_NR); 1891 } 1892 1893 spin_unlock(ptl); 1894 if (flush_needed) 1895 tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE); 1896 } 1897 return 1; 1898 } 1899 1900 #ifndef pmd_move_must_withdraw 1901 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1902 spinlock_t *old_pmd_ptl, 1903 struct vm_area_struct *vma) 1904 { 1905 /* 1906 * With split pmd lock we also need to move preallocated 1907 * PTE page table if new_pmd is on different PMD page table. 1908 * 1909 * We also don't deposit and withdraw tables for file pages. 1910 */ 1911 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1912 } 1913 #endif 1914 1915 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1916 { 1917 #ifdef CONFIG_MEM_SOFT_DIRTY 1918 if (unlikely(is_pmd_migration_entry(pmd))) 1919 pmd = pmd_swp_mksoft_dirty(pmd); 1920 else if (pmd_present(pmd)) 1921 pmd = pmd_mksoft_dirty(pmd); 1922 #endif 1923 return pmd; 1924 } 1925 1926 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1927 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1928 { 1929 spinlock_t *old_ptl, *new_ptl; 1930 pmd_t pmd; 1931 struct mm_struct *mm = vma->vm_mm; 1932 bool force_flush = false; 1933 1934 /* 1935 * The destination pmd shouldn't be established, free_pgtables() 1936 * should have released it; but move_page_tables() might have already 1937 * inserted a page table, if racing against shmem/file collapse. 1938 */ 1939 if (!pmd_none(*new_pmd)) { 1940 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1941 return false; 1942 } 1943 1944 /* 1945 * We don't have to worry about the ordering of src and dst 1946 * ptlocks because exclusive mmap_lock prevents deadlock. 1947 */ 1948 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1949 if (old_ptl) { 1950 new_ptl = pmd_lockptr(mm, new_pmd); 1951 if (new_ptl != old_ptl) 1952 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1953 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1954 if (pmd_present(pmd)) 1955 force_flush = true; 1956 VM_BUG_ON(!pmd_none(*new_pmd)); 1957 1958 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1959 pgtable_t pgtable; 1960 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1961 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1962 } 1963 pmd = move_soft_dirty_pmd(pmd); 1964 set_pmd_at(mm, new_addr, new_pmd, pmd); 1965 if (force_flush) 1966 flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1967 if (new_ptl != old_ptl) 1968 spin_unlock(new_ptl); 1969 spin_unlock(old_ptl); 1970 return true; 1971 } 1972 return false; 1973 } 1974 1975 /* 1976 * Returns 1977 * - 0 if PMD could not be locked 1978 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary 1979 * or if prot_numa but THP migration is not supported 1980 * - HPAGE_PMD_NR if protections changed and TLB flush necessary 1981 */ 1982 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1983 pmd_t *pmd, unsigned long addr, pgprot_t newprot, 1984 unsigned long cp_flags) 1985 { 1986 struct mm_struct *mm = vma->vm_mm; 1987 spinlock_t *ptl; 1988 pmd_t oldpmd, entry; 1989 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1990 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1991 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1992 int ret = 1; 1993 1994 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1995 1996 if (prot_numa && !thp_migration_supported()) 1997 return 1; 1998 1999 ptl = __pmd_trans_huge_lock(pmd, vma); 2000 if (!ptl) 2001 return 0; 2002 2003 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 2004 if (is_swap_pmd(*pmd)) { 2005 swp_entry_t entry = pmd_to_swp_entry(*pmd); 2006 struct folio *folio = pfn_swap_entry_folio(entry); 2007 pmd_t newpmd; 2008 2009 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 2010 if (is_writable_migration_entry(entry)) { 2011 /* 2012 * A protection check is difficult so 2013 * just be safe and disable write 2014 */ 2015 if (folio_test_anon(folio)) 2016 entry = make_readable_exclusive_migration_entry(swp_offset(entry)); 2017 else 2018 entry = make_readable_migration_entry(swp_offset(entry)); 2019 newpmd = swp_entry_to_pmd(entry); 2020 if (pmd_swp_soft_dirty(*pmd)) 2021 newpmd = pmd_swp_mksoft_dirty(newpmd); 2022 } else { 2023 newpmd = *pmd; 2024 } 2025 2026 if (uffd_wp) 2027 newpmd = pmd_swp_mkuffd_wp(newpmd); 2028 else if (uffd_wp_resolve) 2029 newpmd = pmd_swp_clear_uffd_wp(newpmd); 2030 if (!pmd_same(*pmd, newpmd)) 2031 set_pmd_at(mm, addr, pmd, newpmd); 2032 goto unlock; 2033 } 2034 #endif 2035 2036 if (prot_numa) { 2037 struct folio *folio; 2038 bool toptier; 2039 /* 2040 * Avoid trapping faults against the zero page. The read-only 2041 * data is likely to be read-cached on the local CPU and 2042 * local/remote hits to the zero page are not interesting. 2043 */ 2044 if (is_huge_zero_pmd(*pmd)) 2045 goto unlock; 2046 2047 if (pmd_protnone(*pmd)) 2048 goto unlock; 2049 2050 folio = pmd_folio(*pmd); 2051 toptier = node_is_toptier(folio_nid(folio)); 2052 /* 2053 * Skip scanning top tier node if normal numa 2054 * balancing is disabled 2055 */ 2056 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 2057 toptier) 2058 goto unlock; 2059 2060 if (folio_use_access_time(folio)) 2061 folio_xchg_access_time(folio, 2062 jiffies_to_msecs(jiffies)); 2063 } 2064 /* 2065 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 2066 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 2067 * which is also under mmap_read_lock(mm): 2068 * 2069 * CPU0: CPU1: 2070 * change_huge_pmd(prot_numa=1) 2071 * pmdp_huge_get_and_clear_notify() 2072 * madvise_dontneed() 2073 * zap_pmd_range() 2074 * pmd_trans_huge(*pmd) == 0 (without ptl) 2075 * // skip the pmd 2076 * set_pmd_at(); 2077 * // pmd is re-established 2078 * 2079 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 2080 * which may break userspace. 2081 * 2082 * pmdp_invalidate_ad() is required to make sure we don't miss 2083 * dirty/young flags set by hardware. 2084 */ 2085 oldpmd = pmdp_invalidate_ad(vma, addr, pmd); 2086 2087 entry = pmd_modify(oldpmd, newprot); 2088 if (uffd_wp) 2089 entry = pmd_mkuffd_wp(entry); 2090 else if (uffd_wp_resolve) 2091 /* 2092 * Leave the write bit to be handled by PF interrupt 2093 * handler, then things like COW could be properly 2094 * handled. 2095 */ 2096 entry = pmd_clear_uffd_wp(entry); 2097 2098 /* See change_pte_range(). */ 2099 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) && 2100 can_change_pmd_writable(vma, addr, entry)) 2101 entry = pmd_mkwrite(entry, vma); 2102 2103 ret = HPAGE_PMD_NR; 2104 set_pmd_at(mm, addr, pmd, entry); 2105 2106 if (huge_pmd_needs_flush(oldpmd, entry)) 2107 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); 2108 unlock: 2109 spin_unlock(ptl); 2110 return ret; 2111 } 2112 2113 #ifdef CONFIG_USERFAULTFD 2114 /* 2115 * The PT lock for src_pmd and dst_vma/src_vma (for reading) are locked by 2116 * the caller, but it must return after releasing the page_table_lock. 2117 * Just move the page from src_pmd to dst_pmd if possible. 2118 * Return zero if succeeded in moving the page, -EAGAIN if it needs to be 2119 * repeated by the caller, or other errors in case of failure. 2120 */ 2121 int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval, 2122 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma, 2123 unsigned long dst_addr, unsigned long src_addr) 2124 { 2125 pmd_t _dst_pmd, src_pmdval; 2126 struct page *src_page; 2127 struct folio *src_folio; 2128 struct anon_vma *src_anon_vma; 2129 spinlock_t *src_ptl, *dst_ptl; 2130 pgtable_t src_pgtable; 2131 struct mmu_notifier_range range; 2132 int err = 0; 2133 2134 src_pmdval = *src_pmd; 2135 src_ptl = pmd_lockptr(mm, src_pmd); 2136 2137 lockdep_assert_held(src_ptl); 2138 vma_assert_locked(src_vma); 2139 vma_assert_locked(dst_vma); 2140 2141 /* Sanity checks before the operation */ 2142 if (WARN_ON_ONCE(!pmd_none(dst_pmdval)) || WARN_ON_ONCE(src_addr & ~HPAGE_PMD_MASK) || 2143 WARN_ON_ONCE(dst_addr & ~HPAGE_PMD_MASK)) { 2144 spin_unlock(src_ptl); 2145 return -EINVAL; 2146 } 2147 2148 if (!pmd_trans_huge(src_pmdval)) { 2149 spin_unlock(src_ptl); 2150 if (is_pmd_migration_entry(src_pmdval)) { 2151 pmd_migration_entry_wait(mm, &src_pmdval); 2152 return -EAGAIN; 2153 } 2154 return -ENOENT; 2155 } 2156 2157 src_page = pmd_page(src_pmdval); 2158 2159 if (!is_huge_zero_pmd(src_pmdval)) { 2160 if (unlikely(!PageAnonExclusive(src_page))) { 2161 spin_unlock(src_ptl); 2162 return -EBUSY; 2163 } 2164 2165 src_folio = page_folio(src_page); 2166 folio_get(src_folio); 2167 } else 2168 src_folio = NULL; 2169 2170 spin_unlock(src_ptl); 2171 2172 flush_cache_range(src_vma, src_addr, src_addr + HPAGE_PMD_SIZE); 2173 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, src_addr, 2174 src_addr + HPAGE_PMD_SIZE); 2175 mmu_notifier_invalidate_range_start(&range); 2176 2177 if (src_folio) { 2178 folio_lock(src_folio); 2179 2180 /* 2181 * split_huge_page walks the anon_vma chain without the page 2182 * lock. Serialize against it with the anon_vma lock, the page 2183 * lock is not enough. 2184 */ 2185 src_anon_vma = folio_get_anon_vma(src_folio); 2186 if (!src_anon_vma) { 2187 err = -EAGAIN; 2188 goto unlock_folio; 2189 } 2190 anon_vma_lock_write(src_anon_vma); 2191 } else 2192 src_anon_vma = NULL; 2193 2194 dst_ptl = pmd_lockptr(mm, dst_pmd); 2195 double_pt_lock(src_ptl, dst_ptl); 2196 if (unlikely(!pmd_same(*src_pmd, src_pmdval) || 2197 !pmd_same(*dst_pmd, dst_pmdval))) { 2198 err = -EAGAIN; 2199 goto unlock_ptls; 2200 } 2201 if (src_folio) { 2202 if (folio_maybe_dma_pinned(src_folio) || 2203 !PageAnonExclusive(&src_folio->page)) { 2204 err = -EBUSY; 2205 goto unlock_ptls; 2206 } 2207 2208 if (WARN_ON_ONCE(!folio_test_head(src_folio)) || 2209 WARN_ON_ONCE(!folio_test_anon(src_folio))) { 2210 err = -EBUSY; 2211 goto unlock_ptls; 2212 } 2213 2214 src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); 2215 /* Folio got pinned from under us. Put it back and fail the move. */ 2216 if (folio_maybe_dma_pinned(src_folio)) { 2217 set_pmd_at(mm, src_addr, src_pmd, src_pmdval); 2218 err = -EBUSY; 2219 goto unlock_ptls; 2220 } 2221 2222 folio_move_anon_rmap(src_folio, dst_vma); 2223 src_folio->index = linear_page_index(dst_vma, dst_addr); 2224 2225 _dst_pmd = mk_huge_pmd(&src_folio->page, dst_vma->vm_page_prot); 2226 /* Follow mremap() behavior and treat the entry dirty after the move */ 2227 _dst_pmd = pmd_mkwrite(pmd_mkdirty(_dst_pmd), dst_vma); 2228 } else { 2229 src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd); 2230 _dst_pmd = mk_huge_pmd(src_page, dst_vma->vm_page_prot); 2231 } 2232 set_pmd_at(mm, dst_addr, dst_pmd, _dst_pmd); 2233 2234 src_pgtable = pgtable_trans_huge_withdraw(mm, src_pmd); 2235 pgtable_trans_huge_deposit(mm, dst_pmd, src_pgtable); 2236 unlock_ptls: 2237 double_pt_unlock(src_ptl, dst_ptl); 2238 if (src_anon_vma) { 2239 anon_vma_unlock_write(src_anon_vma); 2240 put_anon_vma(src_anon_vma); 2241 } 2242 unlock_folio: 2243 /* unblock rmap walks */ 2244 if (src_folio) 2245 folio_unlock(src_folio); 2246 mmu_notifier_invalidate_range_end(&range); 2247 if (src_folio) 2248 folio_put(src_folio); 2249 return err; 2250 } 2251 #endif /* CONFIG_USERFAULTFD */ 2252 2253 /* 2254 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 2255 * 2256 * Note that if it returns page table lock pointer, this routine returns without 2257 * unlocking page table lock. So callers must unlock it. 2258 */ 2259 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 2260 { 2261 spinlock_t *ptl; 2262 ptl = pmd_lock(vma->vm_mm, pmd); 2263 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 2264 pmd_devmap(*pmd))) 2265 return ptl; 2266 spin_unlock(ptl); 2267 return NULL; 2268 } 2269 2270 /* 2271 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. 2272 * 2273 * Note that if it returns page table lock pointer, this routine returns without 2274 * unlocking page table lock. So callers must unlock it. 2275 */ 2276 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 2277 { 2278 spinlock_t *ptl; 2279 2280 ptl = pud_lock(vma->vm_mm, pud); 2281 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 2282 return ptl; 2283 spin_unlock(ptl); 2284 return NULL; 2285 } 2286 2287 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 2288 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 2289 pud_t *pud, unsigned long addr) 2290 { 2291 spinlock_t *ptl; 2292 2293 ptl = __pud_trans_huge_lock(pud, vma); 2294 if (!ptl) 2295 return 0; 2296 2297 pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm); 2298 tlb_remove_pud_tlb_entry(tlb, pud, addr); 2299 if (vma_is_special_huge(vma)) { 2300 spin_unlock(ptl); 2301 /* No zero page support yet */ 2302 } else { 2303 /* No support for anonymous PUD pages yet */ 2304 BUG(); 2305 } 2306 return 1; 2307 } 2308 2309 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 2310 unsigned long haddr) 2311 { 2312 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 2313 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2314 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 2315 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 2316 2317 count_vm_event(THP_SPLIT_PUD); 2318 2319 pudp_huge_clear_flush(vma, haddr, pud); 2320 } 2321 2322 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 2323 unsigned long address) 2324 { 2325 spinlock_t *ptl; 2326 struct mmu_notifier_range range; 2327 2328 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, 2329 address & HPAGE_PUD_MASK, 2330 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 2331 mmu_notifier_invalidate_range_start(&range); 2332 ptl = pud_lock(vma->vm_mm, pud); 2333 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 2334 goto out; 2335 __split_huge_pud_locked(vma, pud, range.start); 2336 2337 out: 2338 spin_unlock(ptl); 2339 mmu_notifier_invalidate_range_end(&range); 2340 } 2341 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 2342 2343 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2344 unsigned long haddr, pmd_t *pmd) 2345 { 2346 struct mm_struct *mm = vma->vm_mm; 2347 pgtable_t pgtable; 2348 pmd_t _pmd, old_pmd; 2349 unsigned long addr; 2350 pte_t *pte; 2351 int i; 2352 2353 /* 2354 * Leave pmd empty until pte is filled note that it is fine to delay 2355 * notification until mmu_notifier_invalidate_range_end() as we are 2356 * replacing a zero pmd write protected page with a zero pte write 2357 * protected page. 2358 * 2359 * See Documentation/mm/mmu_notifier.rst 2360 */ 2361 old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); 2362 2363 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2364 pmd_populate(mm, &_pmd, pgtable); 2365 2366 pte = pte_offset_map(&_pmd, haddr); 2367 VM_BUG_ON(!pte); 2368 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2369 pte_t entry; 2370 2371 entry = pfn_pte(my_zero_pfn(addr), vma->vm_page_prot); 2372 entry = pte_mkspecial(entry); 2373 if (pmd_uffd_wp(old_pmd)) 2374 entry = pte_mkuffd_wp(entry); 2375 VM_BUG_ON(!pte_none(ptep_get(pte))); 2376 set_pte_at(mm, addr, pte, entry); 2377 pte++; 2378 } 2379 pte_unmap(pte - 1); 2380 smp_wmb(); /* make pte visible before pmd */ 2381 pmd_populate(mm, pmd, pgtable); 2382 } 2383 2384 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2385 unsigned long haddr, bool freeze) 2386 { 2387 struct mm_struct *mm = vma->vm_mm; 2388 struct folio *folio; 2389 struct page *page; 2390 pgtable_t pgtable; 2391 pmd_t old_pmd, _pmd; 2392 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 2393 bool anon_exclusive = false, dirty = false; 2394 unsigned long addr; 2395 pte_t *pte; 2396 int i; 2397 2398 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2399 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2400 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2401 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2402 && !pmd_devmap(*pmd)); 2403 2404 count_vm_event(THP_SPLIT_PMD); 2405 2406 if (!vma_is_anonymous(vma)) { 2407 old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); 2408 /* 2409 * We are going to unmap this huge page. So 2410 * just go ahead and zap it 2411 */ 2412 if (arch_needs_pgtable_deposit()) 2413 zap_deposited_table(mm, pmd); 2414 if (vma_is_special_huge(vma)) 2415 return; 2416 if (unlikely(is_pmd_migration_entry(old_pmd))) { 2417 swp_entry_t entry; 2418 2419 entry = pmd_to_swp_entry(old_pmd); 2420 folio = pfn_swap_entry_folio(entry); 2421 } else { 2422 page = pmd_page(old_pmd); 2423 folio = page_folio(page); 2424 if (!folio_test_dirty(folio) && pmd_dirty(old_pmd)) 2425 folio_mark_dirty(folio); 2426 if (!folio_test_referenced(folio) && pmd_young(old_pmd)) 2427 folio_set_referenced(folio); 2428 folio_remove_rmap_pmd(folio, page, vma); 2429 folio_put(folio); 2430 } 2431 add_mm_counter(mm, mm_counter_file(folio), -HPAGE_PMD_NR); 2432 return; 2433 } 2434 2435 if (is_huge_zero_pmd(*pmd)) { 2436 /* 2437 * FIXME: Do we want to invalidate secondary mmu by calling 2438 * mmu_notifier_arch_invalidate_secondary_tlbs() see comments below 2439 * inside __split_huge_pmd() ? 2440 * 2441 * We are going from a zero huge page write protected to zero 2442 * small page also write protected so it does not seems useful 2443 * to invalidate secondary mmu at this time. 2444 */ 2445 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2446 } 2447 2448 pmd_migration = is_pmd_migration_entry(*pmd); 2449 if (unlikely(pmd_migration)) { 2450 swp_entry_t entry; 2451 2452 old_pmd = *pmd; 2453 entry = pmd_to_swp_entry(old_pmd); 2454 page = pfn_swap_entry_to_page(entry); 2455 write = is_writable_migration_entry(entry); 2456 if (PageAnon(page)) 2457 anon_exclusive = is_readable_exclusive_migration_entry(entry); 2458 young = is_migration_entry_young(entry); 2459 dirty = is_migration_entry_dirty(entry); 2460 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2461 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2462 } else { 2463 /* 2464 * Up to this point the pmd is present and huge and userland has 2465 * the whole access to the hugepage during the split (which 2466 * happens in place). If we overwrite the pmd with the not-huge 2467 * version pointing to the pte here (which of course we could if 2468 * all CPUs were bug free), userland could trigger a small page 2469 * size TLB miss on the small sized TLB while the hugepage TLB 2470 * entry is still established in the huge TLB. Some CPU doesn't 2471 * like that. See 2472 * http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2473 * 383 on page 105. Intel should be safe but is also warns that 2474 * it's only safe if the permission and cache attributes of the 2475 * two entries loaded in the two TLB is identical (which should 2476 * be the case here). But it is generally safer to never allow 2477 * small and huge TLB entries for the same virtual address to be 2478 * loaded simultaneously. So instead of doing "pmd_populate(); 2479 * flush_pmd_tlb_range();" we first mark the current pmd 2480 * notpresent (atomically because here the pmd_trans_huge must 2481 * remain set at all times on the pmd until the split is 2482 * complete for this pmd), then we flush the SMP TLB and finally 2483 * we write the non-huge version of the pmd entry with 2484 * pmd_populate. 2485 */ 2486 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2487 page = pmd_page(old_pmd); 2488 folio = page_folio(page); 2489 if (pmd_dirty(old_pmd)) { 2490 dirty = true; 2491 folio_set_dirty(folio); 2492 } 2493 write = pmd_write(old_pmd); 2494 young = pmd_young(old_pmd); 2495 soft_dirty = pmd_soft_dirty(old_pmd); 2496 uffd_wp = pmd_uffd_wp(old_pmd); 2497 2498 VM_WARN_ON_FOLIO(!folio_ref_count(folio), folio); 2499 VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio); 2500 2501 /* 2502 * Without "freeze", we'll simply split the PMD, propagating the 2503 * PageAnonExclusive() flag for each PTE by setting it for 2504 * each subpage -- no need to (temporarily) clear. 2505 * 2506 * With "freeze" we want to replace mapped pages by 2507 * migration entries right away. This is only possible if we 2508 * managed to clear PageAnonExclusive() -- see 2509 * set_pmd_migration_entry(). 2510 * 2511 * In case we cannot clear PageAnonExclusive(), split the PMD 2512 * only and let try_to_migrate_one() fail later. 2513 * 2514 * See folio_try_share_anon_rmap_pmd(): invalidate PMD first. 2515 */ 2516 anon_exclusive = PageAnonExclusive(page); 2517 if (freeze && anon_exclusive && 2518 folio_try_share_anon_rmap_pmd(folio, page)) 2519 freeze = false; 2520 if (!freeze) { 2521 rmap_t rmap_flags = RMAP_NONE; 2522 2523 folio_ref_add(folio, HPAGE_PMD_NR - 1); 2524 if (anon_exclusive) 2525 rmap_flags |= RMAP_EXCLUSIVE; 2526 folio_add_anon_rmap_ptes(folio, page, HPAGE_PMD_NR, 2527 vma, haddr, rmap_flags); 2528 } 2529 } 2530 2531 /* 2532 * Withdraw the table only after we mark the pmd entry invalid. 2533 * This's critical for some architectures (Power). 2534 */ 2535 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2536 pmd_populate(mm, &_pmd, pgtable); 2537 2538 pte = pte_offset_map(&_pmd, haddr); 2539 VM_BUG_ON(!pte); 2540 2541 /* 2542 * Note that NUMA hinting access restrictions are not transferred to 2543 * avoid any possibility of altering permissions across VMAs. 2544 */ 2545 if (freeze || pmd_migration) { 2546 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2547 pte_t entry; 2548 swp_entry_t swp_entry; 2549 2550 if (write) 2551 swp_entry = make_writable_migration_entry( 2552 page_to_pfn(page + i)); 2553 else if (anon_exclusive) 2554 swp_entry = make_readable_exclusive_migration_entry( 2555 page_to_pfn(page + i)); 2556 else 2557 swp_entry = make_readable_migration_entry( 2558 page_to_pfn(page + i)); 2559 if (young) 2560 swp_entry = make_migration_entry_young(swp_entry); 2561 if (dirty) 2562 swp_entry = make_migration_entry_dirty(swp_entry); 2563 entry = swp_entry_to_pte(swp_entry); 2564 if (soft_dirty) 2565 entry = pte_swp_mksoft_dirty(entry); 2566 if (uffd_wp) 2567 entry = pte_swp_mkuffd_wp(entry); 2568 2569 VM_WARN_ON(!pte_none(ptep_get(pte + i))); 2570 set_pte_at(mm, addr, pte + i, entry); 2571 } 2572 } else { 2573 pte_t entry; 2574 2575 entry = mk_pte(page, READ_ONCE(vma->vm_page_prot)); 2576 if (write) 2577 entry = pte_mkwrite(entry, vma); 2578 if (!young) 2579 entry = pte_mkold(entry); 2580 /* NOTE: this may set soft-dirty too on some archs */ 2581 if (dirty) 2582 entry = pte_mkdirty(entry); 2583 if (soft_dirty) 2584 entry = pte_mksoft_dirty(entry); 2585 if (uffd_wp) 2586 entry = pte_mkuffd_wp(entry); 2587 2588 for (i = 0; i < HPAGE_PMD_NR; i++) 2589 VM_WARN_ON(!pte_none(ptep_get(pte + i))); 2590 2591 set_ptes(mm, haddr, pte, entry, HPAGE_PMD_NR); 2592 } 2593 pte_unmap(pte); 2594 2595 if (!pmd_migration) 2596 folio_remove_rmap_pmd(folio, page, vma); 2597 if (freeze) 2598 put_page(page); 2599 2600 smp_wmb(); /* make pte visible before pmd */ 2601 pmd_populate(mm, pmd, pgtable); 2602 } 2603 2604 void split_huge_pmd_locked(struct vm_area_struct *vma, unsigned long address, 2605 pmd_t *pmd, bool freeze, struct folio *folio) 2606 { 2607 VM_WARN_ON_ONCE(folio && !folio_test_pmd_mappable(folio)); 2608 VM_WARN_ON_ONCE(!IS_ALIGNED(address, HPAGE_PMD_SIZE)); 2609 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); 2610 VM_BUG_ON(freeze && !folio); 2611 2612 /* 2613 * When the caller requests to set up a migration entry, we 2614 * require a folio to check the PMD against. Otherwise, there 2615 * is a risk of replacing the wrong folio. 2616 */ 2617 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || 2618 is_pmd_migration_entry(*pmd)) { 2619 if (folio && folio != pmd_folio(*pmd)) 2620 return; 2621 __split_huge_pmd_locked(vma, pmd, address, freeze); 2622 } 2623 } 2624 2625 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2626 unsigned long address, bool freeze, struct folio *folio) 2627 { 2628 spinlock_t *ptl; 2629 struct mmu_notifier_range range; 2630 2631 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, 2632 address & HPAGE_PMD_MASK, 2633 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2634 mmu_notifier_invalidate_range_start(&range); 2635 ptl = pmd_lock(vma->vm_mm, pmd); 2636 split_huge_pmd_locked(vma, range.start, pmd, freeze, folio); 2637 spin_unlock(ptl); 2638 mmu_notifier_invalidate_range_end(&range); 2639 } 2640 2641 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2642 bool freeze, struct folio *folio) 2643 { 2644 pmd_t *pmd = mm_find_pmd(vma->vm_mm, address); 2645 2646 if (!pmd) 2647 return; 2648 2649 __split_huge_pmd(vma, pmd, address, freeze, folio); 2650 } 2651 2652 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) 2653 { 2654 /* 2655 * If the new address isn't hpage aligned and it could previously 2656 * contain an hugepage: check if we need to split an huge pmd. 2657 */ 2658 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && 2659 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), 2660 ALIGN(address, HPAGE_PMD_SIZE))) 2661 split_huge_pmd_address(vma, address, false, NULL); 2662 } 2663 2664 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2665 unsigned long start, 2666 unsigned long end, 2667 long adjust_next) 2668 { 2669 /* Check if we need to split start first. */ 2670 split_huge_pmd_if_needed(vma, start); 2671 2672 /* Check if we need to split end next. */ 2673 split_huge_pmd_if_needed(vma, end); 2674 2675 /* 2676 * If we're also updating the next vma vm_start, 2677 * check if we need to split it. 2678 */ 2679 if (adjust_next > 0) { 2680 struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end); 2681 unsigned long nstart = next->vm_start; 2682 nstart += adjust_next; 2683 split_huge_pmd_if_needed(next, nstart); 2684 } 2685 } 2686 2687 static void unmap_folio(struct folio *folio) 2688 { 2689 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SYNC | 2690 TTU_BATCH_FLUSH; 2691 2692 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 2693 2694 if (folio_test_pmd_mappable(folio)) 2695 ttu_flags |= TTU_SPLIT_HUGE_PMD; 2696 2697 /* 2698 * Anon pages need migration entries to preserve them, but file 2699 * pages can simply be left unmapped, then faulted back on demand. 2700 * If that is ever changed (perhaps for mlock), update remap_page(). 2701 */ 2702 if (folio_test_anon(folio)) 2703 try_to_migrate(folio, ttu_flags); 2704 else 2705 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); 2706 2707 try_to_unmap_flush(); 2708 } 2709 2710 static bool __discard_anon_folio_pmd_locked(struct vm_area_struct *vma, 2711 unsigned long addr, pmd_t *pmdp, 2712 struct folio *folio) 2713 { 2714 struct mm_struct *mm = vma->vm_mm; 2715 int ref_count, map_count; 2716 pmd_t orig_pmd = *pmdp; 2717 2718 if (folio_test_dirty(folio) || pmd_dirty(orig_pmd)) 2719 return false; 2720 2721 orig_pmd = pmdp_huge_clear_flush(vma, addr, pmdp); 2722 2723 /* 2724 * Syncing against concurrent GUP-fast: 2725 * - clear PMD; barrier; read refcount 2726 * - inc refcount; barrier; read PMD 2727 */ 2728 smp_mb(); 2729 2730 ref_count = folio_ref_count(folio); 2731 map_count = folio_mapcount(folio); 2732 2733 /* 2734 * Order reads for folio refcount and dirty flag 2735 * (see comments in __remove_mapping()). 2736 */ 2737 smp_rmb(); 2738 2739 /* 2740 * If the folio or its PMD is redirtied at this point, or if there 2741 * are unexpected references, we will give up to discard this folio 2742 * and remap it. 2743 * 2744 * The only folio refs must be one from isolation plus the rmap(s). 2745 */ 2746 if (folio_test_dirty(folio) || pmd_dirty(orig_pmd) || 2747 ref_count != map_count + 1) { 2748 set_pmd_at(mm, addr, pmdp, orig_pmd); 2749 return false; 2750 } 2751 2752 folio_remove_rmap_pmd(folio, pmd_page(orig_pmd), vma); 2753 zap_deposited_table(mm, pmdp); 2754 add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR); 2755 if (vma->vm_flags & VM_LOCKED) 2756 mlock_drain_local(); 2757 folio_put(folio); 2758 2759 return true; 2760 } 2761 2762 bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr, 2763 pmd_t *pmdp, struct folio *folio) 2764 { 2765 VM_WARN_ON_FOLIO(!folio_test_pmd_mappable(folio), folio); 2766 VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); 2767 VM_WARN_ON_ONCE(!IS_ALIGNED(addr, HPAGE_PMD_SIZE)); 2768 2769 if (folio_test_anon(folio) && !folio_test_swapbacked(folio)) 2770 return __discard_anon_folio_pmd_locked(vma, addr, pmdp, folio); 2771 2772 return false; 2773 } 2774 2775 static void remap_page(struct folio *folio, unsigned long nr) 2776 { 2777 int i = 0; 2778 2779 /* If unmap_folio() uses try_to_migrate() on file, remove this check */ 2780 if (!folio_test_anon(folio)) 2781 return; 2782 for (;;) { 2783 remove_migration_ptes(folio, folio, true); 2784 i += folio_nr_pages(folio); 2785 if (i >= nr) 2786 break; 2787 folio = folio_next(folio); 2788 } 2789 } 2790 2791 static void lru_add_page_tail(struct page *head, struct page *tail, 2792 struct lruvec *lruvec, struct list_head *list) 2793 { 2794 VM_BUG_ON_PAGE(!PageHead(head), head); 2795 VM_BUG_ON_PAGE(PageLRU(tail), head); 2796 lockdep_assert_held(&lruvec->lru_lock); 2797 2798 if (list) { 2799 /* page reclaim is reclaiming a huge page */ 2800 VM_WARN_ON(PageLRU(head)); 2801 get_page(tail); 2802 list_add_tail(&tail->lru, list); 2803 } else { 2804 /* head is still on lru (and we have it frozen) */ 2805 VM_WARN_ON(!PageLRU(head)); 2806 if (PageUnevictable(tail)) 2807 tail->mlock_count = 0; 2808 else 2809 list_add_tail(&tail->lru, &head->lru); 2810 SetPageLRU(tail); 2811 } 2812 } 2813 2814 static void __split_huge_page_tail(struct folio *folio, int tail, 2815 struct lruvec *lruvec, struct list_head *list, 2816 unsigned int new_order) 2817 { 2818 struct page *head = &folio->page; 2819 struct page *page_tail = head + tail; 2820 /* 2821 * Careful: new_folio is not a "real" folio before we cleared PageTail. 2822 * Don't pass it around before clear_compound_head(). 2823 */ 2824 struct folio *new_folio = (struct folio *)page_tail; 2825 2826 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2827 2828 /* 2829 * Clone page flags before unfreezing refcount. 2830 * 2831 * After successful get_page_unless_zero() might follow flags change, 2832 * for example lock_page() which set PG_waiters. 2833 * 2834 * Note that for mapped sub-pages of an anonymous THP, 2835 * PG_anon_exclusive has been cleared in unmap_folio() and is stored in 2836 * the migration entry instead from where remap_page() will restore it. 2837 * We can still have PG_anon_exclusive set on effectively unmapped and 2838 * unreferenced sub-pages of an anonymous THP: we can simply drop 2839 * PG_anon_exclusive (-> PG_mappedtodisk) for these here. 2840 */ 2841 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2842 page_tail->flags |= (head->flags & 2843 ((1L << PG_referenced) | 2844 (1L << PG_swapbacked) | 2845 (1L << PG_swapcache) | 2846 (1L << PG_mlocked) | 2847 (1L << PG_uptodate) | 2848 (1L << PG_active) | 2849 (1L << PG_workingset) | 2850 (1L << PG_locked) | 2851 (1L << PG_unevictable) | 2852 #ifdef CONFIG_ARCH_USES_PG_ARCH_X 2853 (1L << PG_arch_2) | 2854 (1L << PG_arch_3) | 2855 #endif 2856 (1L << PG_dirty) | 2857 LRU_GEN_MASK | LRU_REFS_MASK)); 2858 2859 /* ->mapping in first and second tail page is replaced by other uses */ 2860 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2861 page_tail); 2862 page_tail->mapping = head->mapping; 2863 page_tail->index = head->index + tail; 2864 2865 /* 2866 * page->private should not be set in tail pages. Fix up and warn once 2867 * if private is unexpectedly set. 2868 */ 2869 if (unlikely(page_tail->private)) { 2870 VM_WARN_ON_ONCE_PAGE(true, page_tail); 2871 page_tail->private = 0; 2872 } 2873 if (folio_test_swapcache(folio)) 2874 new_folio->swap.val = folio->swap.val + tail; 2875 2876 /* Page flags must be visible before we make the page non-compound. */ 2877 smp_wmb(); 2878 2879 /* 2880 * Clear PageTail before unfreezing page refcount. 2881 * 2882 * After successful get_page_unless_zero() might follow put_page() 2883 * which needs correct compound_head(). 2884 */ 2885 clear_compound_head(page_tail); 2886 if (new_order) { 2887 prep_compound_page(page_tail, new_order); 2888 folio_set_large_rmappable(new_folio); 2889 } 2890 2891 /* Finally unfreeze refcount. Additional reference from page cache. */ 2892 page_ref_unfreeze(page_tail, 2893 1 + ((!folio_test_anon(folio) || folio_test_swapcache(folio)) ? 2894 folio_nr_pages(new_folio) : 0)); 2895 2896 if (folio_test_young(folio)) 2897 folio_set_young(new_folio); 2898 if (folio_test_idle(folio)) 2899 folio_set_idle(new_folio); 2900 2901 folio_xchg_last_cpupid(new_folio, folio_last_cpupid(folio)); 2902 2903 /* 2904 * always add to the tail because some iterators expect new 2905 * pages to show after the currently processed elements - e.g. 2906 * migrate_pages 2907 */ 2908 lru_add_page_tail(head, page_tail, lruvec, list); 2909 } 2910 2911 static void __split_huge_page(struct page *page, struct list_head *list, 2912 pgoff_t end, unsigned int new_order) 2913 { 2914 struct folio *folio = page_folio(page); 2915 struct page *head = &folio->page; 2916 struct lruvec *lruvec; 2917 struct address_space *swap_cache = NULL; 2918 unsigned long offset = 0; 2919 int i, nr_dropped = 0; 2920 unsigned int new_nr = 1 << new_order; 2921 int order = folio_order(folio); 2922 unsigned int nr = 1 << order; 2923 2924 /* complete memcg works before add pages to LRU */ 2925 split_page_memcg(head, order, new_order); 2926 2927 if (folio_test_anon(folio) && folio_test_swapcache(folio)) { 2928 offset = swap_cache_index(folio->swap); 2929 swap_cache = swap_address_space(folio->swap); 2930 xa_lock(&swap_cache->i_pages); 2931 } 2932 2933 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ 2934 lruvec = folio_lruvec_lock(folio); 2935 2936 ClearPageHasHWPoisoned(head); 2937 2938 for (i = nr - new_nr; i >= new_nr; i -= new_nr) { 2939 __split_huge_page_tail(folio, i, lruvec, list, new_order); 2940 /* Some pages can be beyond EOF: drop them from page cache */ 2941 if (head[i].index >= end) { 2942 struct folio *tail = page_folio(head + i); 2943 2944 if (shmem_mapping(folio->mapping)) 2945 nr_dropped++; 2946 else if (folio_test_clear_dirty(tail)) 2947 folio_account_cleaned(tail, 2948 inode_to_wb(folio->mapping->host)); 2949 __filemap_remove_folio(tail, NULL); 2950 folio_put(tail); 2951 } else if (!PageAnon(page)) { 2952 __xa_store(&folio->mapping->i_pages, head[i].index, 2953 head + i, 0); 2954 } else if (swap_cache) { 2955 __xa_store(&swap_cache->i_pages, offset + i, 2956 head + i, 0); 2957 } 2958 } 2959 2960 if (!new_order) 2961 ClearPageCompound(head); 2962 else { 2963 struct folio *new_folio = (struct folio *)head; 2964 2965 folio_set_order(new_folio, new_order); 2966 } 2967 unlock_page_lruvec(lruvec); 2968 /* Caller disabled irqs, so they are still disabled here */ 2969 2970 split_page_owner(head, order, new_order); 2971 pgalloc_tag_split(head, 1 << order); 2972 2973 /* See comment in __split_huge_page_tail() */ 2974 if (folio_test_anon(folio)) { 2975 /* Additional pin to swap cache */ 2976 if (folio_test_swapcache(folio)) { 2977 folio_ref_add(folio, 1 + new_nr); 2978 xa_unlock(&swap_cache->i_pages); 2979 } else { 2980 folio_ref_inc(folio); 2981 } 2982 } else { 2983 /* Additional pin to page cache */ 2984 folio_ref_add(folio, 1 + new_nr); 2985 xa_unlock(&folio->mapping->i_pages); 2986 } 2987 local_irq_enable(); 2988 2989 if (nr_dropped) 2990 shmem_uncharge(folio->mapping->host, nr_dropped); 2991 remap_page(folio, nr); 2992 2993 /* 2994 * set page to its compound_head when split to non order-0 pages, so 2995 * we can skip unlocking it below, since PG_locked is transferred to 2996 * the compound_head of the page and the caller will unlock it. 2997 */ 2998 if (new_order) 2999 page = compound_head(page); 3000 3001 for (i = 0; i < nr; i += new_nr) { 3002 struct page *subpage = head + i; 3003 struct folio *new_folio = page_folio(subpage); 3004 if (subpage == page) 3005 continue; 3006 folio_unlock(new_folio); 3007 3008 /* 3009 * Subpages may be freed if there wasn't any mapping 3010 * like if add_to_swap() is running on a lru page that 3011 * had its mapping zapped. And freeing these pages 3012 * requires taking the lru_lock so we do the put_page 3013 * of the tail pages after the split is complete. 3014 */ 3015 free_page_and_swap_cache(subpage); 3016 } 3017 } 3018 3019 /* Racy check whether the huge page can be split */ 3020 bool can_split_folio(struct folio *folio, int *pextra_pins) 3021 { 3022 int extra_pins; 3023 3024 /* Additional pins from page cache */ 3025 if (folio_test_anon(folio)) 3026 extra_pins = folio_test_swapcache(folio) ? 3027 folio_nr_pages(folio) : 0; 3028 else 3029 extra_pins = folio_nr_pages(folio); 3030 if (pextra_pins) 3031 *pextra_pins = extra_pins; 3032 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1; 3033 } 3034 3035 /* 3036 * This function splits a large folio into smaller folios of order @new_order. 3037 * @page can point to any page of the large folio to split. The split operation 3038 * does not change the position of @page. 3039 * 3040 * Prerequisites: 3041 * 3042 * 1) The caller must hold a reference on the @page's owning folio, also known 3043 * as the large folio. 3044 * 3045 * 2) The large folio must be locked. 3046 * 3047 * 3) The folio must not be pinned. Any unexpected folio references, including 3048 * GUP pins, will result in the folio not getting split; instead, the caller 3049 * will receive an -EAGAIN. 3050 * 3051 * 4) @new_order > 1, usually. Splitting to order-1 anonymous folios is not 3052 * supported for non-file-backed folios, because folio->_deferred_list, which 3053 * is used by partially mapped folios, is stored in subpage 2, but an order-1 3054 * folio only has subpages 0 and 1. File-backed order-1 folios are supported, 3055 * since they do not use _deferred_list. 3056 * 3057 * After splitting, the caller's folio reference will be transferred to @page, 3058 * resulting in a raised refcount of @page after this call. The other pages may 3059 * be freed if they are not mapped. 3060 * 3061 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 3062 * 3063 * Pages in @new_order will inherit the mapping, flags, and so on from the 3064 * huge page. 3065 * 3066 * Returns 0 if the huge page was split successfully. 3067 * 3068 * Returns -EAGAIN if the folio has unexpected reference (e.g., GUP) or if 3069 * the folio was concurrently removed from the page cache. 3070 * 3071 * Returns -EBUSY when trying to split the huge zeropage, if the folio is 3072 * under writeback, if fs-specific folio metadata cannot currently be 3073 * released, or if some unexpected race happened (e.g., anon VMA disappeared, 3074 * truncation). 3075 * 3076 * Returns -EINVAL when trying to split to an order that is incompatible 3077 * with the folio. Splitting to order 0 is compatible with all folios. 3078 */ 3079 int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, 3080 unsigned int new_order) 3081 { 3082 struct folio *folio = page_folio(page); 3083 struct deferred_split *ds_queue = get_deferred_split_queue(folio); 3084 /* reset xarray order to new order after split */ 3085 XA_STATE_ORDER(xas, &folio->mapping->i_pages, folio->index, new_order); 3086 struct anon_vma *anon_vma = NULL; 3087 struct address_space *mapping = NULL; 3088 int order = folio_order(folio); 3089 int extra_pins, ret; 3090 pgoff_t end; 3091 bool is_hzp; 3092 3093 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); 3094 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 3095 3096 if (new_order >= folio_order(folio)) 3097 return -EINVAL; 3098 3099 if (folio_test_anon(folio)) { 3100 /* order-1 is not supported for anonymous THP. */ 3101 if (new_order == 1) { 3102 VM_WARN_ONCE(1, "Cannot split to order-1 folio"); 3103 return -EINVAL; 3104 } 3105 } else if (new_order) { 3106 /* Split shmem folio to non-zero order not supported */ 3107 if (shmem_mapping(folio->mapping)) { 3108 VM_WARN_ONCE(1, 3109 "Cannot split shmem folio to non-0 order"); 3110 return -EINVAL; 3111 } 3112 /* 3113 * No split if the file system does not support large folio. 3114 * Note that we might still have THPs in such mappings due to 3115 * CONFIG_READ_ONLY_THP_FOR_FS. But in that case, the mapping 3116 * does not actually support large folios properly. 3117 */ 3118 if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && 3119 !mapping_large_folio_support(folio->mapping)) { 3120 VM_WARN_ONCE(1, 3121 "Cannot split file folio to non-0 order"); 3122 return -EINVAL; 3123 } 3124 } 3125 3126 /* Only swapping a whole PMD-mapped folio is supported */ 3127 if (folio_test_swapcache(folio) && new_order) 3128 return -EINVAL; 3129 3130 is_hzp = is_huge_zero_folio(folio); 3131 if (is_hzp) { 3132 pr_warn_ratelimited("Called split_huge_page for huge zero page\n"); 3133 return -EBUSY; 3134 } 3135 3136 if (folio_test_writeback(folio)) 3137 return -EBUSY; 3138 3139 if (folio_test_anon(folio)) { 3140 /* 3141 * The caller does not necessarily hold an mmap_lock that would 3142 * prevent the anon_vma disappearing so we first we take a 3143 * reference to it and then lock the anon_vma for write. This 3144 * is similar to folio_lock_anon_vma_read except the write lock 3145 * is taken to serialise against parallel split or collapse 3146 * operations. 3147 */ 3148 anon_vma = folio_get_anon_vma(folio); 3149 if (!anon_vma) { 3150 ret = -EBUSY; 3151 goto out; 3152 } 3153 end = -1; 3154 mapping = NULL; 3155 anon_vma_lock_write(anon_vma); 3156 } else { 3157 gfp_t gfp; 3158 3159 mapping = folio->mapping; 3160 3161 /* Truncated ? */ 3162 if (!mapping) { 3163 ret = -EBUSY; 3164 goto out; 3165 } 3166 3167 gfp = current_gfp_context(mapping_gfp_mask(mapping) & 3168 GFP_RECLAIM_MASK); 3169 3170 if (!filemap_release_folio(folio, gfp)) { 3171 ret = -EBUSY; 3172 goto out; 3173 } 3174 3175 xas_split_alloc(&xas, folio, folio_order(folio), gfp); 3176 if (xas_error(&xas)) { 3177 ret = xas_error(&xas); 3178 goto out; 3179 } 3180 3181 anon_vma = NULL; 3182 i_mmap_lock_read(mapping); 3183 3184 /* 3185 *__split_huge_page() may need to trim off pages beyond EOF: 3186 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 3187 * which cannot be nested inside the page tree lock. So note 3188 * end now: i_size itself may be changed at any moment, but 3189 * folio lock is good enough to serialize the trimming. 3190 */ 3191 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 3192 if (shmem_mapping(mapping)) 3193 end = shmem_fallocend(mapping->host, end); 3194 } 3195 3196 /* 3197 * Racy check if we can split the page, before unmap_folio() will 3198 * split PMDs 3199 */ 3200 if (!can_split_folio(folio, &extra_pins)) { 3201 ret = -EAGAIN; 3202 goto out_unlock; 3203 } 3204 3205 unmap_folio(folio); 3206 3207 /* block interrupt reentry in xa_lock and spinlock */ 3208 local_irq_disable(); 3209 if (mapping) { 3210 /* 3211 * Check if the folio is present in page cache. 3212 * We assume all tail are present too, if folio is there. 3213 */ 3214 xas_lock(&xas); 3215 xas_reset(&xas); 3216 if (xas_load(&xas) != folio) 3217 goto fail; 3218 } 3219 3220 /* Prevent deferred_split_scan() touching ->_refcount */ 3221 spin_lock(&ds_queue->split_queue_lock); 3222 if (folio_ref_freeze(folio, 1 + extra_pins)) { 3223 if (folio_order(folio) > 1 && 3224 !list_empty(&folio->_deferred_list)) { 3225 ds_queue->split_queue_len--; 3226 /* 3227 * Reinitialize page_deferred_list after removing the 3228 * page from the split_queue, otherwise a subsequent 3229 * split will see list corruption when checking the 3230 * page_deferred_list. 3231 */ 3232 list_del_init(&folio->_deferred_list); 3233 } 3234 spin_unlock(&ds_queue->split_queue_lock); 3235 if (mapping) { 3236 int nr = folio_nr_pages(folio); 3237 3238 xas_split(&xas, folio, folio_order(folio)); 3239 if (folio_test_pmd_mappable(folio) && 3240 new_order < HPAGE_PMD_ORDER) { 3241 if (folio_test_swapbacked(folio)) { 3242 __lruvec_stat_mod_folio(folio, 3243 NR_SHMEM_THPS, -nr); 3244 } else { 3245 __lruvec_stat_mod_folio(folio, 3246 NR_FILE_THPS, -nr); 3247 filemap_nr_thps_dec(mapping); 3248 } 3249 } 3250 } 3251 3252 __split_huge_page(page, list, end, new_order); 3253 ret = 0; 3254 } else { 3255 spin_unlock(&ds_queue->split_queue_lock); 3256 fail: 3257 if (mapping) 3258 xas_unlock(&xas); 3259 local_irq_enable(); 3260 remap_page(folio, folio_nr_pages(folio)); 3261 ret = -EAGAIN; 3262 } 3263 3264 out_unlock: 3265 if (anon_vma) { 3266 anon_vma_unlock_write(anon_vma); 3267 put_anon_vma(anon_vma); 3268 } 3269 if (mapping) 3270 i_mmap_unlock_read(mapping); 3271 out: 3272 xas_destroy(&xas); 3273 if (order == HPAGE_PMD_ORDER) 3274 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 3275 count_mthp_stat(order, !ret ? MTHP_STAT_SPLIT : MTHP_STAT_SPLIT_FAILED); 3276 return ret; 3277 } 3278 3279 void __folio_undo_large_rmappable(struct folio *folio) 3280 { 3281 struct deferred_split *ds_queue; 3282 unsigned long flags; 3283 3284 ds_queue = get_deferred_split_queue(folio); 3285 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3286 if (!list_empty(&folio->_deferred_list)) { 3287 ds_queue->split_queue_len--; 3288 list_del_init(&folio->_deferred_list); 3289 } 3290 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3291 } 3292 3293 void deferred_split_folio(struct folio *folio) 3294 { 3295 struct deferred_split *ds_queue = get_deferred_split_queue(folio); 3296 #ifdef CONFIG_MEMCG 3297 struct mem_cgroup *memcg = folio_memcg(folio); 3298 #endif 3299 unsigned long flags; 3300 3301 /* 3302 * Order 1 folios have no space for a deferred list, but we also 3303 * won't waste much memory by not adding them to the deferred list. 3304 */ 3305 if (folio_order(folio) <= 1) 3306 return; 3307 3308 /* 3309 * The try_to_unmap() in page reclaim path might reach here too, 3310 * this may cause a race condition to corrupt deferred split queue. 3311 * And, if page reclaim is already handling the same folio, it is 3312 * unnecessary to handle it again in shrinker. 3313 * 3314 * Check the swapcache flag to determine if the folio is being 3315 * handled by page reclaim since THP swap would add the folio into 3316 * swap cache before calling try_to_unmap(). 3317 */ 3318 if (folio_test_swapcache(folio)) 3319 return; 3320 3321 if (!list_empty(&folio->_deferred_list)) 3322 return; 3323 3324 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3325 if (list_empty(&folio->_deferred_list)) { 3326 if (folio_test_pmd_mappable(folio)) 3327 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 3328 count_mthp_stat(folio_order(folio), MTHP_STAT_SPLIT_DEFERRED); 3329 list_add_tail(&folio->_deferred_list, &ds_queue->split_queue); 3330 ds_queue->split_queue_len++; 3331 #ifdef CONFIG_MEMCG 3332 if (memcg) 3333 set_shrinker_bit(memcg, folio_nid(folio), 3334 deferred_split_shrinker->id); 3335 #endif 3336 } 3337 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3338 } 3339 3340 static unsigned long deferred_split_count(struct shrinker *shrink, 3341 struct shrink_control *sc) 3342 { 3343 struct pglist_data *pgdata = NODE_DATA(sc->nid); 3344 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 3345 3346 #ifdef CONFIG_MEMCG 3347 if (sc->memcg) 3348 ds_queue = &sc->memcg->deferred_split_queue; 3349 #endif 3350 return READ_ONCE(ds_queue->split_queue_len); 3351 } 3352 3353 static unsigned long deferred_split_scan(struct shrinker *shrink, 3354 struct shrink_control *sc) 3355 { 3356 struct pglist_data *pgdata = NODE_DATA(sc->nid); 3357 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 3358 unsigned long flags; 3359 LIST_HEAD(list); 3360 struct folio *folio, *next; 3361 int split = 0; 3362 3363 #ifdef CONFIG_MEMCG 3364 if (sc->memcg) 3365 ds_queue = &sc->memcg->deferred_split_queue; 3366 #endif 3367 3368 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3369 /* Take pin on all head pages to avoid freeing them under us */ 3370 list_for_each_entry_safe(folio, next, &ds_queue->split_queue, 3371 _deferred_list) { 3372 if (folio_try_get(folio)) { 3373 list_move(&folio->_deferred_list, &list); 3374 } else { 3375 /* We lost race with folio_put() */ 3376 list_del_init(&folio->_deferred_list); 3377 ds_queue->split_queue_len--; 3378 } 3379 if (!--sc->nr_to_scan) 3380 break; 3381 } 3382 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3383 3384 list_for_each_entry_safe(folio, next, &list, _deferred_list) { 3385 if (!folio_trylock(folio)) 3386 goto next; 3387 /* split_huge_page() removes page from list on success */ 3388 if (!split_folio(folio)) 3389 split++; 3390 folio_unlock(folio); 3391 next: 3392 folio_put(folio); 3393 } 3394 3395 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 3396 list_splice_tail(&list, &ds_queue->split_queue); 3397 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 3398 3399 /* 3400 * Stop shrinker if we didn't split any page, but the queue is empty. 3401 * This can happen if pages were freed under us. 3402 */ 3403 if (!split && list_empty(&ds_queue->split_queue)) 3404 return SHRINK_STOP; 3405 return split; 3406 } 3407 3408 #ifdef CONFIG_DEBUG_FS 3409 static void split_huge_pages_all(void) 3410 { 3411 struct zone *zone; 3412 struct page *page; 3413 struct folio *folio; 3414 unsigned long pfn, max_zone_pfn; 3415 unsigned long total = 0, split = 0; 3416 3417 pr_debug("Split all THPs\n"); 3418 for_each_zone(zone) { 3419 if (!managed_zone(zone)) 3420 continue; 3421 max_zone_pfn = zone_end_pfn(zone); 3422 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 3423 int nr_pages; 3424 3425 page = pfn_to_online_page(pfn); 3426 if (!page || PageTail(page)) 3427 continue; 3428 folio = page_folio(page); 3429 if (!folio_try_get(folio)) 3430 continue; 3431 3432 if (unlikely(page_folio(page) != folio)) 3433 goto next; 3434 3435 if (zone != folio_zone(folio)) 3436 goto next; 3437 3438 if (!folio_test_large(folio) 3439 || folio_test_hugetlb(folio) 3440 || !folio_test_lru(folio)) 3441 goto next; 3442 3443 total++; 3444 folio_lock(folio); 3445 nr_pages = folio_nr_pages(folio); 3446 if (!split_folio(folio)) 3447 split++; 3448 pfn += nr_pages - 1; 3449 folio_unlock(folio); 3450 next: 3451 folio_put(folio); 3452 cond_resched(); 3453 } 3454 } 3455 3456 pr_debug("%lu of %lu THP split\n", split, total); 3457 } 3458 3459 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) 3460 { 3461 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || 3462 is_vm_hugetlb_page(vma); 3463 } 3464 3465 static int split_huge_pages_pid(int pid, unsigned long vaddr_start, 3466 unsigned long vaddr_end, unsigned int new_order) 3467 { 3468 int ret = 0; 3469 struct task_struct *task; 3470 struct mm_struct *mm; 3471 unsigned long total = 0, split = 0; 3472 unsigned long addr; 3473 3474 vaddr_start &= PAGE_MASK; 3475 vaddr_end &= PAGE_MASK; 3476 3477 /* Find the task_struct from pid */ 3478 rcu_read_lock(); 3479 task = find_task_by_vpid(pid); 3480 if (!task) { 3481 rcu_read_unlock(); 3482 ret = -ESRCH; 3483 goto out; 3484 } 3485 get_task_struct(task); 3486 rcu_read_unlock(); 3487 3488 /* Find the mm_struct */ 3489 mm = get_task_mm(task); 3490 put_task_struct(task); 3491 3492 if (!mm) { 3493 ret = -EINVAL; 3494 goto out; 3495 } 3496 3497 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n", 3498 pid, vaddr_start, vaddr_end); 3499 3500 mmap_read_lock(mm); 3501 /* 3502 * always increase addr by PAGE_SIZE, since we could have a PTE page 3503 * table filled with PTE-mapped THPs, each of which is distinct. 3504 */ 3505 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { 3506 struct vm_area_struct *vma = vma_lookup(mm, addr); 3507 struct page *page; 3508 struct folio *folio; 3509 3510 if (!vma) 3511 break; 3512 3513 /* skip special VMA and hugetlb VMA */ 3514 if (vma_not_suitable_for_thp_split(vma)) { 3515 addr = vma->vm_end; 3516 continue; 3517 } 3518 3519 /* FOLL_DUMP to ignore special (like zero) pages */ 3520 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); 3521 3522 if (IS_ERR_OR_NULL(page)) 3523 continue; 3524 3525 folio = page_folio(page); 3526 if (!is_transparent_hugepage(folio)) 3527 goto next; 3528 3529 if (new_order >= folio_order(folio)) 3530 goto next; 3531 3532 total++; 3533 /* 3534 * For folios with private, split_huge_page_to_list_to_order() 3535 * will try to drop it before split and then check if the folio 3536 * can be split or not. So skip the check here. 3537 */ 3538 if (!folio_test_private(folio) && 3539 !can_split_folio(folio, NULL)) 3540 goto next; 3541 3542 if (!folio_trylock(folio)) 3543 goto next; 3544 3545 if (!split_folio_to_order(folio, new_order)) 3546 split++; 3547 3548 folio_unlock(folio); 3549 next: 3550 folio_put(folio); 3551 cond_resched(); 3552 } 3553 mmap_read_unlock(mm); 3554 mmput(mm); 3555 3556 pr_debug("%lu of %lu THP split\n", split, total); 3557 3558 out: 3559 return ret; 3560 } 3561 3562 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, 3563 pgoff_t off_end, unsigned int new_order) 3564 { 3565 struct filename *file; 3566 struct file *candidate; 3567 struct address_space *mapping; 3568 int ret = -EINVAL; 3569 pgoff_t index; 3570 int nr_pages = 1; 3571 unsigned long total = 0, split = 0; 3572 3573 file = getname_kernel(file_path); 3574 if (IS_ERR(file)) 3575 return ret; 3576 3577 candidate = file_open_name(file, O_RDONLY, 0); 3578 if (IS_ERR(candidate)) 3579 goto out; 3580 3581 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", 3582 file_path, off_start, off_end); 3583 3584 mapping = candidate->f_mapping; 3585 3586 for (index = off_start; index < off_end; index += nr_pages) { 3587 struct folio *folio = filemap_get_folio(mapping, index); 3588 3589 nr_pages = 1; 3590 if (IS_ERR(folio)) 3591 continue; 3592 3593 if (!folio_test_large(folio)) 3594 goto next; 3595 3596 total++; 3597 nr_pages = folio_nr_pages(folio); 3598 3599 if (new_order >= folio_order(folio)) 3600 goto next; 3601 3602 if (!folio_trylock(folio)) 3603 goto next; 3604 3605 if (!split_folio_to_order(folio, new_order)) 3606 split++; 3607 3608 folio_unlock(folio); 3609 next: 3610 folio_put(folio); 3611 cond_resched(); 3612 } 3613 3614 filp_close(candidate, NULL); 3615 ret = 0; 3616 3617 pr_debug("%lu of %lu file-backed THP split\n", split, total); 3618 out: 3619 putname(file); 3620 return ret; 3621 } 3622 3623 #define MAX_INPUT_BUF_SZ 255 3624 3625 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, 3626 size_t count, loff_t *ppops) 3627 { 3628 static DEFINE_MUTEX(split_debug_mutex); 3629 ssize_t ret; 3630 /* 3631 * hold pid, start_vaddr, end_vaddr, new_order or 3632 * file_path, off_start, off_end, new_order 3633 */ 3634 char input_buf[MAX_INPUT_BUF_SZ]; 3635 int pid; 3636 unsigned long vaddr_start, vaddr_end; 3637 unsigned int new_order = 0; 3638 3639 ret = mutex_lock_interruptible(&split_debug_mutex); 3640 if (ret) 3641 return ret; 3642 3643 ret = -EFAULT; 3644 3645 memset(input_buf, 0, MAX_INPUT_BUF_SZ); 3646 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) 3647 goto out; 3648 3649 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; 3650 3651 if (input_buf[0] == '/') { 3652 char *tok; 3653 char *buf = input_buf; 3654 char file_path[MAX_INPUT_BUF_SZ]; 3655 pgoff_t off_start = 0, off_end = 0; 3656 size_t input_len = strlen(input_buf); 3657 3658 tok = strsep(&buf, ","); 3659 if (tok) { 3660 strcpy(file_path, tok); 3661 } else { 3662 ret = -EINVAL; 3663 goto out; 3664 } 3665 3666 ret = sscanf(buf, "0x%lx,0x%lx,%d", &off_start, &off_end, &new_order); 3667 if (ret != 2 && ret != 3) { 3668 ret = -EINVAL; 3669 goto out; 3670 } 3671 ret = split_huge_pages_in_file(file_path, off_start, off_end, new_order); 3672 if (!ret) 3673 ret = input_len; 3674 3675 goto out; 3676 } 3677 3678 ret = sscanf(input_buf, "%d,0x%lx,0x%lx,%d", &pid, &vaddr_start, &vaddr_end, &new_order); 3679 if (ret == 1 && pid == 1) { 3680 split_huge_pages_all(); 3681 ret = strlen(input_buf); 3682 goto out; 3683 } else if (ret != 3 && ret != 4) { 3684 ret = -EINVAL; 3685 goto out; 3686 } 3687 3688 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end, new_order); 3689 if (!ret) 3690 ret = strlen(input_buf); 3691 out: 3692 mutex_unlock(&split_debug_mutex); 3693 return ret; 3694 3695 } 3696 3697 static const struct file_operations split_huge_pages_fops = { 3698 .owner = THIS_MODULE, 3699 .write = split_huge_pages_write, 3700 .llseek = no_llseek, 3701 }; 3702 3703 static int __init split_huge_pages_debugfs(void) 3704 { 3705 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 3706 &split_huge_pages_fops); 3707 return 0; 3708 } 3709 late_initcall(split_huge_pages_debugfs); 3710 #endif 3711 3712 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 3713 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 3714 struct page *page) 3715 { 3716 struct folio *folio = page_folio(page); 3717 struct vm_area_struct *vma = pvmw->vma; 3718 struct mm_struct *mm = vma->vm_mm; 3719 unsigned long address = pvmw->address; 3720 bool anon_exclusive; 3721 pmd_t pmdval; 3722 swp_entry_t entry; 3723 pmd_t pmdswp; 3724 3725 if (!(pvmw->pmd && !pvmw->pte)) 3726 return 0; 3727 3728 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 3729 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 3730 3731 /* See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */ 3732 anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(page); 3733 if (anon_exclusive && folio_try_share_anon_rmap_pmd(folio, page)) { 3734 set_pmd_at(mm, address, pvmw->pmd, pmdval); 3735 return -EBUSY; 3736 } 3737 3738 if (pmd_dirty(pmdval)) 3739 folio_mark_dirty(folio); 3740 if (pmd_write(pmdval)) 3741 entry = make_writable_migration_entry(page_to_pfn(page)); 3742 else if (anon_exclusive) 3743 entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); 3744 else 3745 entry = make_readable_migration_entry(page_to_pfn(page)); 3746 if (pmd_young(pmdval)) 3747 entry = make_migration_entry_young(entry); 3748 if (pmd_dirty(pmdval)) 3749 entry = make_migration_entry_dirty(entry); 3750 pmdswp = swp_entry_to_pmd(entry); 3751 if (pmd_soft_dirty(pmdval)) 3752 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3753 if (pmd_uffd_wp(pmdval)) 3754 pmdswp = pmd_swp_mkuffd_wp(pmdswp); 3755 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3756 folio_remove_rmap_pmd(folio, page, vma); 3757 folio_put(folio); 3758 trace_set_migration_pmd(address, pmd_val(pmdswp)); 3759 3760 return 0; 3761 } 3762 3763 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3764 { 3765 struct folio *folio = page_folio(new); 3766 struct vm_area_struct *vma = pvmw->vma; 3767 struct mm_struct *mm = vma->vm_mm; 3768 unsigned long address = pvmw->address; 3769 unsigned long haddr = address & HPAGE_PMD_MASK; 3770 pmd_t pmde; 3771 swp_entry_t entry; 3772 3773 if (!(pvmw->pmd && !pvmw->pte)) 3774 return; 3775 3776 entry = pmd_to_swp_entry(*pvmw->pmd); 3777 folio_get(folio); 3778 pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot)); 3779 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3780 pmde = pmd_mksoft_dirty(pmde); 3781 if (is_writable_migration_entry(entry)) 3782 pmde = pmd_mkwrite(pmde, vma); 3783 if (pmd_swp_uffd_wp(*pvmw->pmd)) 3784 pmde = pmd_mkuffd_wp(pmde); 3785 if (!is_migration_entry_young(entry)) 3786 pmde = pmd_mkold(pmde); 3787 /* NOTE: this may contain setting soft-dirty on some archs */ 3788 if (folio_test_dirty(folio) && is_migration_entry_dirty(entry)) 3789 pmde = pmd_mkdirty(pmde); 3790 3791 if (folio_test_anon(folio)) { 3792 rmap_t rmap_flags = RMAP_NONE; 3793 3794 if (!is_readable_migration_entry(entry)) 3795 rmap_flags |= RMAP_EXCLUSIVE; 3796 3797 folio_add_anon_rmap_pmd(folio, new, vma, haddr, rmap_flags); 3798 } else { 3799 folio_add_file_rmap_pmd(folio, new, vma); 3800 } 3801 VM_BUG_ON(pmd_write(pmde) && folio_test_anon(folio) && !PageAnonExclusive(new)); 3802 set_pmd_at(mm, haddr, pvmw->pmd, pmde); 3803 3804 /* No need to invalidate - it was non-present before */ 3805 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3806 trace_remove_migration_pmd(address, pmd_val(pmde)); 3807 } 3808 #endif 3809