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/khugepaged.h> 24 #include <linux/freezer.h> 25 #include <linux/pfn_t.h> 26 #include <linux/mman.h> 27 #include <linux/memremap.h> 28 #include <linux/pagemap.h> 29 #include <linux/debugfs.h> 30 #include <linux/migrate.h> 31 #include <linux/hashtable.h> 32 #include <linux/userfaultfd_k.h> 33 #include <linux/page_idle.h> 34 #include <linux/shmem_fs.h> 35 #include <linux/oom.h> 36 #include <linux/numa.h> 37 #include <linux/page_owner.h> 38 #include <linux/sched/sysctl.h> 39 #include <linux/memory-tiers.h> 40 41 #include <asm/tlb.h> 42 #include <asm/pgalloc.h> 43 #include "internal.h" 44 #include "swap.h" 45 46 #define CREATE_TRACE_POINTS 47 #include <trace/events/thp.h> 48 49 /* 50 * By default, transparent hugepage support is disabled in order to avoid 51 * risking an increased memory footprint for applications that are not 52 * guaranteed to benefit from it. When transparent hugepage support is 53 * enabled, it is for all mappings, and khugepaged scans all mappings. 54 * Defrag is invoked by khugepaged hugepage allocations and by page faults 55 * for all hugepage allocations. 56 */ 57 unsigned long transparent_hugepage_flags __read_mostly = 58 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 59 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 60 #endif 61 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 62 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 63 #endif 64 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 65 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 66 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 67 68 static struct shrinker *deferred_split_shrinker; 69 static unsigned long deferred_split_count(struct shrinker *shrink, 70 struct shrink_control *sc); 71 static unsigned long deferred_split_scan(struct shrinker *shrink, 72 struct shrink_control *sc); 73 74 static atomic_t huge_zero_refcount; 75 struct page *huge_zero_page __read_mostly; 76 unsigned long huge_zero_pfn __read_mostly = ~0UL; 77 78 bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags, 79 bool smaps, bool in_pf, bool enforce_sysfs) 80 { 81 if (!vma->vm_mm) /* vdso */ 82 return false; 83 84 /* 85 * Explicitly disabled through madvise or prctl, or some 86 * architectures may disable THP for some mappings, for 87 * example, s390 kvm. 88 * */ 89 if ((vm_flags & VM_NOHUGEPAGE) || 90 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) 91 return false; 92 /* 93 * If the hardware/firmware marked hugepage support disabled. 94 */ 95 if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED)) 96 return false; 97 98 /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ 99 if (vma_is_dax(vma)) 100 return in_pf; 101 102 /* 103 * khugepaged special VMA and hugetlb VMA. 104 * Must be checked after dax since some dax mappings may have 105 * VM_MIXEDMAP set. 106 */ 107 if (!in_pf && !smaps && (vm_flags & VM_NO_KHUGEPAGED)) 108 return false; 109 110 /* 111 * Check alignment for file vma and size for both file and anon vma. 112 * 113 * Skip the check for page fault. Huge fault does the check in fault 114 * handlers. And this check is not suitable for huge PUD fault. 115 */ 116 if (!in_pf && 117 !transhuge_vma_suitable(vma, (vma->vm_end - HPAGE_PMD_SIZE))) 118 return false; 119 120 /* 121 * Enabled via shmem mount options or sysfs settings. 122 * Must be done before hugepage flags check since shmem has its 123 * own flags. 124 */ 125 if (!in_pf && shmem_file(vma->vm_file)) 126 return shmem_is_huge(file_inode(vma->vm_file), vma->vm_pgoff, 127 !enforce_sysfs, vma->vm_mm, vm_flags); 128 129 /* Enforce sysfs THP requirements as necessary */ 130 if (enforce_sysfs && 131 (!hugepage_flags_enabled() || (!(vm_flags & VM_HUGEPAGE) && 132 !hugepage_flags_always()))) 133 return false; 134 135 if (!vma_is_anonymous(vma)) { 136 /* 137 * Trust that ->huge_fault() handlers know what they are doing 138 * in fault path. 139 */ 140 if (((in_pf || smaps)) && vma->vm_ops->huge_fault) 141 return true; 142 /* Only regular file is valid in collapse path */ 143 if (((!in_pf || smaps)) && file_thp_enabled(vma)) 144 return true; 145 return false; 146 } 147 148 if (vma_is_temporary_stack(vma)) 149 return false; 150 151 /* 152 * THPeligible bit of smaps should show 1 for proper VMAs even 153 * though anon_vma is not initialized yet. 154 * 155 * Allow page fault since anon_vma may be not initialized until 156 * the first page fault. 157 */ 158 if (!vma->anon_vma) 159 return (smaps || in_pf); 160 161 return true; 162 } 163 164 static bool get_huge_zero_page(void) 165 { 166 struct page *zero_page; 167 retry: 168 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 169 return true; 170 171 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 172 HPAGE_PMD_ORDER); 173 if (!zero_page) { 174 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 175 return false; 176 } 177 preempt_disable(); 178 if (cmpxchg(&huge_zero_page, NULL, zero_page)) { 179 preempt_enable(); 180 __free_pages(zero_page, compound_order(zero_page)); 181 goto retry; 182 } 183 WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page)); 184 185 /* We take additional reference here. It will be put back by shrinker */ 186 atomic_set(&huge_zero_refcount, 2); 187 preempt_enable(); 188 count_vm_event(THP_ZERO_PAGE_ALLOC); 189 return true; 190 } 191 192 static void put_huge_zero_page(void) 193 { 194 /* 195 * Counter should never go to zero here. Only shrinker can put 196 * last reference. 197 */ 198 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 199 } 200 201 struct page *mm_get_huge_zero_page(struct mm_struct *mm) 202 { 203 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 204 return READ_ONCE(huge_zero_page); 205 206 if (!get_huge_zero_page()) 207 return NULL; 208 209 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 210 put_huge_zero_page(); 211 212 return READ_ONCE(huge_zero_page); 213 } 214 215 void mm_put_huge_zero_page(struct mm_struct *mm) 216 { 217 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 218 put_huge_zero_page(); 219 } 220 221 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 222 struct shrink_control *sc) 223 { 224 /* we can free zero page only if last reference remains */ 225 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 226 } 227 228 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 229 struct shrink_control *sc) 230 { 231 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 232 struct page *zero_page = xchg(&huge_zero_page, NULL); 233 BUG_ON(zero_page == NULL); 234 WRITE_ONCE(huge_zero_pfn, ~0UL); 235 __free_pages(zero_page, compound_order(zero_page)); 236 return HPAGE_PMD_NR; 237 } 238 239 return 0; 240 } 241 242 static struct shrinker *huge_zero_page_shrinker; 243 244 #ifdef CONFIG_SYSFS 245 static ssize_t enabled_show(struct kobject *kobj, 246 struct kobj_attribute *attr, char *buf) 247 { 248 const char *output; 249 250 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 251 output = "[always] madvise never"; 252 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 253 &transparent_hugepage_flags)) 254 output = "always [madvise] never"; 255 else 256 output = "always madvise [never]"; 257 258 return sysfs_emit(buf, "%s\n", output); 259 } 260 261 static ssize_t enabled_store(struct kobject *kobj, 262 struct kobj_attribute *attr, 263 const char *buf, size_t count) 264 { 265 ssize_t ret = count; 266 267 if (sysfs_streq(buf, "always")) { 268 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 269 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 270 } else if (sysfs_streq(buf, "madvise")) { 271 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 272 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 273 } else if (sysfs_streq(buf, "never")) { 274 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 275 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 276 } else 277 ret = -EINVAL; 278 279 if (ret > 0) { 280 int err = start_stop_khugepaged(); 281 if (err) 282 ret = err; 283 } 284 return ret; 285 } 286 287 static struct kobj_attribute enabled_attr = __ATTR_RW(enabled); 288 289 ssize_t single_hugepage_flag_show(struct kobject *kobj, 290 struct kobj_attribute *attr, char *buf, 291 enum transparent_hugepage_flag flag) 292 { 293 return sysfs_emit(buf, "%d\n", 294 !!test_bit(flag, &transparent_hugepage_flags)); 295 } 296 297 ssize_t single_hugepage_flag_store(struct kobject *kobj, 298 struct kobj_attribute *attr, 299 const char *buf, size_t count, 300 enum transparent_hugepage_flag flag) 301 { 302 unsigned long value; 303 int ret; 304 305 ret = kstrtoul(buf, 10, &value); 306 if (ret < 0) 307 return ret; 308 if (value > 1) 309 return -EINVAL; 310 311 if (value) 312 set_bit(flag, &transparent_hugepage_flags); 313 else 314 clear_bit(flag, &transparent_hugepage_flags); 315 316 return count; 317 } 318 319 static ssize_t defrag_show(struct kobject *kobj, 320 struct kobj_attribute *attr, char *buf) 321 { 322 const char *output; 323 324 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 325 &transparent_hugepage_flags)) 326 output = "[always] defer defer+madvise madvise never"; 327 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 328 &transparent_hugepage_flags)) 329 output = "always [defer] defer+madvise madvise never"; 330 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 331 &transparent_hugepage_flags)) 332 output = "always defer [defer+madvise] madvise never"; 333 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 334 &transparent_hugepage_flags)) 335 output = "always defer defer+madvise [madvise] never"; 336 else 337 output = "always defer defer+madvise madvise [never]"; 338 339 return sysfs_emit(buf, "%s\n", output); 340 } 341 342 static ssize_t defrag_store(struct kobject *kobj, 343 struct kobj_attribute *attr, 344 const char *buf, size_t count) 345 { 346 if (sysfs_streq(buf, "always")) { 347 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 348 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 349 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 350 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 351 } else if (sysfs_streq(buf, "defer+madvise")) { 352 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 353 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 354 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 355 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 356 } else if (sysfs_streq(buf, "defer")) { 357 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 358 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 359 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 360 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 361 } else if (sysfs_streq(buf, "madvise")) { 362 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 363 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 364 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 365 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 366 } else if (sysfs_streq(buf, "never")) { 367 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 368 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 369 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 370 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 371 } else 372 return -EINVAL; 373 374 return count; 375 } 376 static struct kobj_attribute defrag_attr = __ATTR_RW(defrag); 377 378 static ssize_t use_zero_page_show(struct kobject *kobj, 379 struct kobj_attribute *attr, char *buf) 380 { 381 return single_hugepage_flag_show(kobj, attr, buf, 382 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 383 } 384 static ssize_t use_zero_page_store(struct kobject *kobj, 385 struct kobj_attribute *attr, const char *buf, size_t count) 386 { 387 return single_hugepage_flag_store(kobj, attr, buf, count, 388 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 389 } 390 static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page); 391 392 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 393 struct kobj_attribute *attr, char *buf) 394 { 395 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); 396 } 397 static struct kobj_attribute hpage_pmd_size_attr = 398 __ATTR_RO(hpage_pmd_size); 399 400 static struct attribute *hugepage_attr[] = { 401 &enabled_attr.attr, 402 &defrag_attr.attr, 403 &use_zero_page_attr.attr, 404 &hpage_pmd_size_attr.attr, 405 #ifdef CONFIG_SHMEM 406 &shmem_enabled_attr.attr, 407 #endif 408 NULL, 409 }; 410 411 static const struct attribute_group hugepage_attr_group = { 412 .attrs = hugepage_attr, 413 }; 414 415 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 416 { 417 int err; 418 419 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 420 if (unlikely(!*hugepage_kobj)) { 421 pr_err("failed to create transparent hugepage kobject\n"); 422 return -ENOMEM; 423 } 424 425 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 426 if (err) { 427 pr_err("failed to register transparent hugepage group\n"); 428 goto delete_obj; 429 } 430 431 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 432 if (err) { 433 pr_err("failed to register transparent hugepage group\n"); 434 goto remove_hp_group; 435 } 436 437 return 0; 438 439 remove_hp_group: 440 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 441 delete_obj: 442 kobject_put(*hugepage_kobj); 443 return err; 444 } 445 446 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 447 { 448 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 449 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 450 kobject_put(hugepage_kobj); 451 } 452 #else 453 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 454 { 455 return 0; 456 } 457 458 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 459 { 460 } 461 #endif /* CONFIG_SYSFS */ 462 463 static int __init thp_shrinker_init(void) 464 { 465 huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero"); 466 if (!huge_zero_page_shrinker) 467 return -ENOMEM; 468 469 deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE | 470 SHRINKER_MEMCG_AWARE | 471 SHRINKER_NONSLAB, 472 "thp-deferred_split"); 473 if (!deferred_split_shrinker) { 474 shrinker_free(huge_zero_page_shrinker); 475 return -ENOMEM; 476 } 477 478 huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count; 479 huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan; 480 shrinker_register(huge_zero_page_shrinker); 481 482 deferred_split_shrinker->count_objects = deferred_split_count; 483 deferred_split_shrinker->scan_objects = deferred_split_scan; 484 shrinker_register(deferred_split_shrinker); 485 486 return 0; 487 } 488 489 static void __init thp_shrinker_exit(void) 490 { 491 shrinker_free(huge_zero_page_shrinker); 492 shrinker_free(deferred_split_shrinker); 493 } 494 495 static int __init hugepage_init(void) 496 { 497 int err; 498 struct kobject *hugepage_kobj; 499 500 if (!has_transparent_hugepage()) { 501 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED; 502 return -EINVAL; 503 } 504 505 /* 506 * hugepages can't be allocated by the buddy allocator 507 */ 508 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER > MAX_ORDER); 509 /* 510 * we use page->mapping and page->index in second tail page 511 * as list_head: assuming THP order >= 2 512 */ 513 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); 514 515 err = hugepage_init_sysfs(&hugepage_kobj); 516 if (err) 517 goto err_sysfs; 518 519 err = khugepaged_init(); 520 if (err) 521 goto err_slab; 522 523 err = thp_shrinker_init(); 524 if (err) 525 goto err_shrinker; 526 527 /* 528 * By default disable transparent hugepages on smaller systems, 529 * where the extra memory used could hurt more than TLB overhead 530 * is likely to save. The admin can still enable it through /sys. 531 */ 532 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 533 transparent_hugepage_flags = 0; 534 return 0; 535 } 536 537 err = start_stop_khugepaged(); 538 if (err) 539 goto err_khugepaged; 540 541 return 0; 542 err_khugepaged: 543 thp_shrinker_exit(); 544 err_shrinker: 545 khugepaged_destroy(); 546 err_slab: 547 hugepage_exit_sysfs(hugepage_kobj); 548 err_sysfs: 549 return err; 550 } 551 subsys_initcall(hugepage_init); 552 553 static int __init setup_transparent_hugepage(char *str) 554 { 555 int ret = 0; 556 if (!str) 557 goto out; 558 if (!strcmp(str, "always")) { 559 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 560 &transparent_hugepage_flags); 561 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 562 &transparent_hugepage_flags); 563 ret = 1; 564 } else if (!strcmp(str, "madvise")) { 565 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 566 &transparent_hugepage_flags); 567 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 568 &transparent_hugepage_flags); 569 ret = 1; 570 } else if (!strcmp(str, "never")) { 571 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 572 &transparent_hugepage_flags); 573 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 574 &transparent_hugepage_flags); 575 ret = 1; 576 } 577 out: 578 if (!ret) 579 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 580 return ret; 581 } 582 __setup("transparent_hugepage=", setup_transparent_hugepage); 583 584 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 585 { 586 if (likely(vma->vm_flags & VM_WRITE)) 587 pmd = pmd_mkwrite(pmd, vma); 588 return pmd; 589 } 590 591 #ifdef CONFIG_MEMCG 592 static inline 593 struct deferred_split *get_deferred_split_queue(struct folio *folio) 594 { 595 struct mem_cgroup *memcg = folio_memcg(folio); 596 struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); 597 598 if (memcg) 599 return &memcg->deferred_split_queue; 600 else 601 return &pgdat->deferred_split_queue; 602 } 603 #else 604 static inline 605 struct deferred_split *get_deferred_split_queue(struct folio *folio) 606 { 607 struct pglist_data *pgdat = NODE_DATA(folio_nid(folio)); 608 609 return &pgdat->deferred_split_queue; 610 } 611 #endif 612 613 void folio_prep_large_rmappable(struct folio *folio) 614 { 615 VM_BUG_ON_FOLIO(folio_order(folio) < 2, folio); 616 INIT_LIST_HEAD(&folio->_deferred_list); 617 folio_set_large_rmappable(folio); 618 } 619 620 static inline bool is_transparent_hugepage(struct folio *folio) 621 { 622 if (!folio_test_large(folio)) 623 return false; 624 625 return is_huge_zero_page(&folio->page) || 626 folio_test_large_rmappable(folio); 627 } 628 629 static unsigned long __thp_get_unmapped_area(struct file *filp, 630 unsigned long addr, unsigned long len, 631 loff_t off, unsigned long flags, unsigned long size) 632 { 633 loff_t off_end = off + len; 634 loff_t off_align = round_up(off, size); 635 unsigned long len_pad, ret; 636 637 if (off_end <= off_align || (off_end - off_align) < size) 638 return 0; 639 640 len_pad = len + size; 641 if (len_pad < len || (off + len_pad) < off) 642 return 0; 643 644 ret = current->mm->get_unmapped_area(filp, addr, len_pad, 645 off >> PAGE_SHIFT, flags); 646 647 /* 648 * The failure might be due to length padding. The caller will retry 649 * without the padding. 650 */ 651 if (IS_ERR_VALUE(ret)) 652 return 0; 653 654 /* 655 * Do not try to align to THP boundary if allocation at the address 656 * hint succeeds. 657 */ 658 if (ret == addr) 659 return addr; 660 661 ret += (off - ret) & (size - 1); 662 return ret; 663 } 664 665 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 666 unsigned long len, unsigned long pgoff, unsigned long flags) 667 { 668 unsigned long ret; 669 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 670 671 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE); 672 if (ret) 673 return ret; 674 675 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 676 } 677 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 678 679 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 680 struct page *page, gfp_t gfp) 681 { 682 struct vm_area_struct *vma = vmf->vma; 683 struct folio *folio = page_folio(page); 684 pgtable_t pgtable; 685 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 686 vm_fault_t ret = 0; 687 688 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 689 690 if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) { 691 folio_put(folio); 692 count_vm_event(THP_FAULT_FALLBACK); 693 count_vm_event(THP_FAULT_FALLBACK_CHARGE); 694 return VM_FAULT_FALLBACK; 695 } 696 folio_throttle_swaprate(folio, gfp); 697 698 pgtable = pte_alloc_one(vma->vm_mm); 699 if (unlikely(!pgtable)) { 700 ret = VM_FAULT_OOM; 701 goto release; 702 } 703 704 clear_huge_page(page, vmf->address, HPAGE_PMD_NR); 705 /* 706 * The memory barrier inside __folio_mark_uptodate makes sure that 707 * clear_huge_page writes become visible before the set_pmd_at() 708 * write. 709 */ 710 __folio_mark_uptodate(folio); 711 712 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 713 if (unlikely(!pmd_none(*vmf->pmd))) { 714 goto unlock_release; 715 } else { 716 pmd_t entry; 717 718 ret = check_stable_address_space(vma->vm_mm); 719 if (ret) 720 goto unlock_release; 721 722 /* Deliver the page fault to userland */ 723 if (userfaultfd_missing(vma)) { 724 spin_unlock(vmf->ptl); 725 folio_put(folio); 726 pte_free(vma->vm_mm, pgtable); 727 ret = handle_userfault(vmf, VM_UFFD_MISSING); 728 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 729 return ret; 730 } 731 732 entry = mk_huge_pmd(page, vma->vm_page_prot); 733 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 734 folio_add_new_anon_rmap(folio, vma, haddr); 735 folio_add_lru_vma(folio, vma); 736 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 737 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 738 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 739 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 740 mm_inc_nr_ptes(vma->vm_mm); 741 spin_unlock(vmf->ptl); 742 count_vm_event(THP_FAULT_ALLOC); 743 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); 744 } 745 746 return 0; 747 unlock_release: 748 spin_unlock(vmf->ptl); 749 release: 750 if (pgtable) 751 pte_free(vma->vm_mm, pgtable); 752 folio_put(folio); 753 return ret; 754 755 } 756 757 /* 758 * always: directly stall for all thp allocations 759 * defer: wake kswapd and fail if not immediately available 760 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 761 * fail if not immediately available 762 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 763 * available 764 * never: never stall for any thp allocation 765 */ 766 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) 767 { 768 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); 769 770 /* Always do synchronous compaction */ 771 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 772 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 773 774 /* Kick kcompactd and fail quickly */ 775 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 776 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; 777 778 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 779 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 780 return GFP_TRANSHUGE_LIGHT | 781 (vma_madvised ? __GFP_DIRECT_RECLAIM : 782 __GFP_KSWAPD_RECLAIM); 783 784 /* Only do synchronous compaction if madvised */ 785 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 786 return GFP_TRANSHUGE_LIGHT | 787 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 788 789 return GFP_TRANSHUGE_LIGHT; 790 } 791 792 /* Caller must hold page table lock. */ 793 static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, 794 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 795 struct page *zero_page) 796 { 797 pmd_t entry; 798 if (!pmd_none(*pmd)) 799 return; 800 entry = mk_pmd(zero_page, vma->vm_page_prot); 801 entry = pmd_mkhuge(entry); 802 pgtable_trans_huge_deposit(mm, pmd, pgtable); 803 set_pmd_at(mm, haddr, pmd, entry); 804 mm_inc_nr_ptes(mm); 805 } 806 807 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 808 { 809 struct vm_area_struct *vma = vmf->vma; 810 gfp_t gfp; 811 struct folio *folio; 812 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 813 814 if (!transhuge_vma_suitable(vma, haddr)) 815 return VM_FAULT_FALLBACK; 816 if (unlikely(anon_vma_prepare(vma))) 817 return VM_FAULT_OOM; 818 khugepaged_enter_vma(vma, vma->vm_flags); 819 820 if (!(vmf->flags & FAULT_FLAG_WRITE) && 821 !mm_forbids_zeropage(vma->vm_mm) && 822 transparent_hugepage_use_zero_page()) { 823 pgtable_t pgtable; 824 struct page *zero_page; 825 vm_fault_t ret; 826 pgtable = pte_alloc_one(vma->vm_mm); 827 if (unlikely(!pgtable)) 828 return VM_FAULT_OOM; 829 zero_page = mm_get_huge_zero_page(vma->vm_mm); 830 if (unlikely(!zero_page)) { 831 pte_free(vma->vm_mm, pgtable); 832 count_vm_event(THP_FAULT_FALLBACK); 833 return VM_FAULT_FALLBACK; 834 } 835 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 836 ret = 0; 837 if (pmd_none(*vmf->pmd)) { 838 ret = check_stable_address_space(vma->vm_mm); 839 if (ret) { 840 spin_unlock(vmf->ptl); 841 pte_free(vma->vm_mm, pgtable); 842 } else if (userfaultfd_missing(vma)) { 843 spin_unlock(vmf->ptl); 844 pte_free(vma->vm_mm, pgtable); 845 ret = handle_userfault(vmf, VM_UFFD_MISSING); 846 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 847 } else { 848 set_huge_zero_page(pgtable, vma->vm_mm, vma, 849 haddr, vmf->pmd, zero_page); 850 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 851 spin_unlock(vmf->ptl); 852 } 853 } else { 854 spin_unlock(vmf->ptl); 855 pte_free(vma->vm_mm, pgtable); 856 } 857 return ret; 858 } 859 gfp = vma_thp_gfp_mask(vma); 860 folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true); 861 if (unlikely(!folio)) { 862 count_vm_event(THP_FAULT_FALLBACK); 863 return VM_FAULT_FALLBACK; 864 } 865 return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp); 866 } 867 868 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 869 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 870 pgtable_t pgtable) 871 { 872 struct mm_struct *mm = vma->vm_mm; 873 pmd_t entry; 874 spinlock_t *ptl; 875 876 ptl = pmd_lock(mm, pmd); 877 if (!pmd_none(*pmd)) { 878 if (write) { 879 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 880 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 881 goto out_unlock; 882 } 883 entry = pmd_mkyoung(*pmd); 884 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 885 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 886 update_mmu_cache_pmd(vma, addr, pmd); 887 } 888 889 goto out_unlock; 890 } 891 892 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 893 if (pfn_t_devmap(pfn)) 894 entry = pmd_mkdevmap(entry); 895 if (write) { 896 entry = pmd_mkyoung(pmd_mkdirty(entry)); 897 entry = maybe_pmd_mkwrite(entry, vma); 898 } 899 900 if (pgtable) { 901 pgtable_trans_huge_deposit(mm, pmd, pgtable); 902 mm_inc_nr_ptes(mm); 903 pgtable = NULL; 904 } 905 906 set_pmd_at(mm, addr, pmd, entry); 907 update_mmu_cache_pmd(vma, addr, pmd); 908 909 out_unlock: 910 spin_unlock(ptl); 911 if (pgtable) 912 pte_free(mm, pgtable); 913 } 914 915 /** 916 * vmf_insert_pfn_pmd - insert a pmd size pfn 917 * @vmf: Structure describing the fault 918 * @pfn: pfn to insert 919 * @write: whether it's a write fault 920 * 921 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info. 922 * 923 * Return: vm_fault_t value. 924 */ 925 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) 926 { 927 unsigned long addr = vmf->address & PMD_MASK; 928 struct vm_area_struct *vma = vmf->vma; 929 pgprot_t pgprot = vma->vm_page_prot; 930 pgtable_t pgtable = NULL; 931 932 /* 933 * If we had pmd_special, we could avoid all these restrictions, 934 * but we need to be consistent with PTEs and architectures that 935 * can't support a 'special' bit. 936 */ 937 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 938 !pfn_t_devmap(pfn)); 939 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 940 (VM_PFNMAP|VM_MIXEDMAP)); 941 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 942 943 if (addr < vma->vm_start || addr >= vma->vm_end) 944 return VM_FAULT_SIGBUS; 945 946 if (arch_needs_pgtable_deposit()) { 947 pgtable = pte_alloc_one(vma->vm_mm); 948 if (!pgtable) 949 return VM_FAULT_OOM; 950 } 951 952 track_pfn_insert(vma, &pgprot, pfn); 953 954 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 955 return VM_FAULT_NOPAGE; 956 } 957 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); 958 959 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 960 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 961 { 962 if (likely(vma->vm_flags & VM_WRITE)) 963 pud = pud_mkwrite(pud); 964 return pud; 965 } 966 967 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 968 pud_t *pud, pfn_t pfn, bool write) 969 { 970 struct mm_struct *mm = vma->vm_mm; 971 pgprot_t prot = vma->vm_page_prot; 972 pud_t entry; 973 spinlock_t *ptl; 974 975 ptl = pud_lock(mm, pud); 976 if (!pud_none(*pud)) { 977 if (write) { 978 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 979 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 980 goto out_unlock; 981 } 982 entry = pud_mkyoung(*pud); 983 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 984 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 985 update_mmu_cache_pud(vma, addr, pud); 986 } 987 goto out_unlock; 988 } 989 990 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 991 if (pfn_t_devmap(pfn)) 992 entry = pud_mkdevmap(entry); 993 if (write) { 994 entry = pud_mkyoung(pud_mkdirty(entry)); 995 entry = maybe_pud_mkwrite(entry, vma); 996 } 997 set_pud_at(mm, addr, pud, entry); 998 update_mmu_cache_pud(vma, addr, pud); 999 1000 out_unlock: 1001 spin_unlock(ptl); 1002 } 1003 1004 /** 1005 * vmf_insert_pfn_pud - insert a pud size pfn 1006 * @vmf: Structure describing the fault 1007 * @pfn: pfn to insert 1008 * @write: whether it's a write fault 1009 * 1010 * Insert a pud size pfn. See vmf_insert_pfn() for additional info. 1011 * 1012 * Return: vm_fault_t value. 1013 */ 1014 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) 1015 { 1016 unsigned long addr = vmf->address & PUD_MASK; 1017 struct vm_area_struct *vma = vmf->vma; 1018 pgprot_t pgprot = vma->vm_page_prot; 1019 1020 /* 1021 * If we had pud_special, we could avoid all these restrictions, 1022 * but we need to be consistent with PTEs and architectures that 1023 * can't support a 'special' bit. 1024 */ 1025 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 1026 !pfn_t_devmap(pfn)); 1027 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1028 (VM_PFNMAP|VM_MIXEDMAP)); 1029 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1030 1031 if (addr < vma->vm_start || addr >= vma->vm_end) 1032 return VM_FAULT_SIGBUS; 1033 1034 track_pfn_insert(vma, &pgprot, pfn); 1035 1036 insert_pfn_pud(vma, addr, vmf->pud, pfn, write); 1037 return VM_FAULT_NOPAGE; 1038 } 1039 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); 1040 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1041 1042 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 1043 pmd_t *pmd, bool write) 1044 { 1045 pmd_t _pmd; 1046 1047 _pmd = pmd_mkyoung(*pmd); 1048 if (write) 1049 _pmd = pmd_mkdirty(_pmd); 1050 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 1051 pmd, _pmd, write)) 1052 update_mmu_cache_pmd(vma, addr, pmd); 1053 } 1054 1055 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 1056 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 1057 { 1058 unsigned long pfn = pmd_pfn(*pmd); 1059 struct mm_struct *mm = vma->vm_mm; 1060 struct page *page; 1061 int ret; 1062 1063 assert_spin_locked(pmd_lockptr(mm, pmd)); 1064 1065 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 1066 return NULL; 1067 1068 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 1069 /* pass */; 1070 else 1071 return NULL; 1072 1073 if (flags & FOLL_TOUCH) 1074 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1075 1076 /* 1077 * device mapped pages can only be returned if the 1078 * caller will manage the page reference count. 1079 */ 1080 if (!(flags & (FOLL_GET | FOLL_PIN))) 1081 return ERR_PTR(-EEXIST); 1082 1083 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 1084 *pgmap = get_dev_pagemap(pfn, *pgmap); 1085 if (!*pgmap) 1086 return ERR_PTR(-EFAULT); 1087 page = pfn_to_page(pfn); 1088 ret = try_grab_page(page, flags); 1089 if (ret) 1090 page = ERR_PTR(ret); 1091 1092 return page; 1093 } 1094 1095 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1096 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1097 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) 1098 { 1099 spinlock_t *dst_ptl, *src_ptl; 1100 struct page *src_page; 1101 pmd_t pmd; 1102 pgtable_t pgtable = NULL; 1103 int ret = -ENOMEM; 1104 1105 /* Skip if can be re-fill on fault */ 1106 if (!vma_is_anonymous(dst_vma)) 1107 return 0; 1108 1109 pgtable = pte_alloc_one(dst_mm); 1110 if (unlikely(!pgtable)) 1111 goto out; 1112 1113 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1114 src_ptl = pmd_lockptr(src_mm, src_pmd); 1115 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1116 1117 ret = -EAGAIN; 1118 pmd = *src_pmd; 1119 1120 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1121 if (unlikely(is_swap_pmd(pmd))) { 1122 swp_entry_t entry = pmd_to_swp_entry(pmd); 1123 1124 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1125 if (!is_readable_migration_entry(entry)) { 1126 entry = make_readable_migration_entry( 1127 swp_offset(entry)); 1128 pmd = swp_entry_to_pmd(entry); 1129 if (pmd_swp_soft_dirty(*src_pmd)) 1130 pmd = pmd_swp_mksoft_dirty(pmd); 1131 if (pmd_swp_uffd_wp(*src_pmd)) 1132 pmd = pmd_swp_mkuffd_wp(pmd); 1133 set_pmd_at(src_mm, addr, src_pmd, pmd); 1134 } 1135 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1136 mm_inc_nr_ptes(dst_mm); 1137 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1138 if (!userfaultfd_wp(dst_vma)) 1139 pmd = pmd_swp_clear_uffd_wp(pmd); 1140 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1141 ret = 0; 1142 goto out_unlock; 1143 } 1144 #endif 1145 1146 if (unlikely(!pmd_trans_huge(pmd))) { 1147 pte_free(dst_mm, pgtable); 1148 goto out_unlock; 1149 } 1150 /* 1151 * When page table lock is held, the huge zero pmd should not be 1152 * under splitting since we don't split the page itself, only pmd to 1153 * a page table. 1154 */ 1155 if (is_huge_zero_pmd(pmd)) { 1156 /* 1157 * get_huge_zero_page() will never allocate a new page here, 1158 * since we already have a zero page to copy. It just takes a 1159 * reference. 1160 */ 1161 mm_get_huge_zero_page(dst_mm); 1162 goto out_zero_page; 1163 } 1164 1165 src_page = pmd_page(pmd); 1166 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1167 1168 get_page(src_page); 1169 if (unlikely(page_try_dup_anon_rmap(src_page, true, src_vma))) { 1170 /* Page maybe pinned: split and retry the fault on PTEs. */ 1171 put_page(src_page); 1172 pte_free(dst_mm, pgtable); 1173 spin_unlock(src_ptl); 1174 spin_unlock(dst_ptl); 1175 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); 1176 return -EAGAIN; 1177 } 1178 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1179 out_zero_page: 1180 mm_inc_nr_ptes(dst_mm); 1181 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1182 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1183 if (!userfaultfd_wp(dst_vma)) 1184 pmd = pmd_clear_uffd_wp(pmd); 1185 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1186 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1187 1188 ret = 0; 1189 out_unlock: 1190 spin_unlock(src_ptl); 1191 spin_unlock(dst_ptl); 1192 out: 1193 return ret; 1194 } 1195 1196 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1197 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1198 pud_t *pud, bool write) 1199 { 1200 pud_t _pud; 1201 1202 _pud = pud_mkyoung(*pud); 1203 if (write) 1204 _pud = pud_mkdirty(_pud); 1205 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1206 pud, _pud, write)) 1207 update_mmu_cache_pud(vma, addr, pud); 1208 } 1209 1210 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1211 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1212 { 1213 unsigned long pfn = pud_pfn(*pud); 1214 struct mm_struct *mm = vma->vm_mm; 1215 struct page *page; 1216 int ret; 1217 1218 assert_spin_locked(pud_lockptr(mm, pud)); 1219 1220 if (flags & FOLL_WRITE && !pud_write(*pud)) 1221 return NULL; 1222 1223 if (pud_present(*pud) && pud_devmap(*pud)) 1224 /* pass */; 1225 else 1226 return NULL; 1227 1228 if (flags & FOLL_TOUCH) 1229 touch_pud(vma, addr, pud, flags & FOLL_WRITE); 1230 1231 /* 1232 * device mapped pages can only be returned if the 1233 * caller will manage the page reference count. 1234 * 1235 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here: 1236 */ 1237 if (!(flags & (FOLL_GET | FOLL_PIN))) 1238 return ERR_PTR(-EEXIST); 1239 1240 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1241 *pgmap = get_dev_pagemap(pfn, *pgmap); 1242 if (!*pgmap) 1243 return ERR_PTR(-EFAULT); 1244 page = pfn_to_page(pfn); 1245 1246 ret = try_grab_page(page, flags); 1247 if (ret) 1248 page = ERR_PTR(ret); 1249 1250 return page; 1251 } 1252 1253 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1254 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1255 struct vm_area_struct *vma) 1256 { 1257 spinlock_t *dst_ptl, *src_ptl; 1258 pud_t pud; 1259 int ret; 1260 1261 dst_ptl = pud_lock(dst_mm, dst_pud); 1262 src_ptl = pud_lockptr(src_mm, src_pud); 1263 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1264 1265 ret = -EAGAIN; 1266 pud = *src_pud; 1267 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1268 goto out_unlock; 1269 1270 /* 1271 * When page table lock is held, the huge zero pud should not be 1272 * under splitting since we don't split the page itself, only pud to 1273 * a page table. 1274 */ 1275 if (is_huge_zero_pud(pud)) { 1276 /* No huge zero pud yet */ 1277 } 1278 1279 /* 1280 * TODO: once we support anonymous pages, use page_try_dup_anon_rmap() 1281 * and split if duplicating fails. 1282 */ 1283 pudp_set_wrprotect(src_mm, addr, src_pud); 1284 pud = pud_mkold(pud_wrprotect(pud)); 1285 set_pud_at(dst_mm, addr, dst_pud, pud); 1286 1287 ret = 0; 1288 out_unlock: 1289 spin_unlock(src_ptl); 1290 spin_unlock(dst_ptl); 1291 return ret; 1292 } 1293 1294 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1295 { 1296 bool write = vmf->flags & FAULT_FLAG_WRITE; 1297 1298 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1299 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1300 goto unlock; 1301 1302 touch_pud(vmf->vma, vmf->address, vmf->pud, write); 1303 unlock: 1304 spin_unlock(vmf->ptl); 1305 } 1306 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1307 1308 void huge_pmd_set_accessed(struct vm_fault *vmf) 1309 { 1310 bool write = vmf->flags & FAULT_FLAG_WRITE; 1311 1312 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1313 if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) 1314 goto unlock; 1315 1316 touch_pmd(vmf->vma, vmf->address, vmf->pmd, write); 1317 1318 unlock: 1319 spin_unlock(vmf->ptl); 1320 } 1321 1322 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) 1323 { 1324 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; 1325 struct vm_area_struct *vma = vmf->vma; 1326 struct folio *folio; 1327 struct page *page; 1328 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1329 pmd_t orig_pmd = vmf->orig_pmd; 1330 1331 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1332 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1333 1334 if (is_huge_zero_pmd(orig_pmd)) 1335 goto fallback; 1336 1337 spin_lock(vmf->ptl); 1338 1339 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1340 spin_unlock(vmf->ptl); 1341 return 0; 1342 } 1343 1344 page = pmd_page(orig_pmd); 1345 folio = page_folio(page); 1346 VM_BUG_ON_PAGE(!PageHead(page), page); 1347 1348 /* Early check when only holding the PT lock. */ 1349 if (PageAnonExclusive(page)) 1350 goto reuse; 1351 1352 if (!folio_trylock(folio)) { 1353 folio_get(folio); 1354 spin_unlock(vmf->ptl); 1355 folio_lock(folio); 1356 spin_lock(vmf->ptl); 1357 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1358 spin_unlock(vmf->ptl); 1359 folio_unlock(folio); 1360 folio_put(folio); 1361 return 0; 1362 } 1363 folio_put(folio); 1364 } 1365 1366 /* Recheck after temporarily dropping the PT lock. */ 1367 if (PageAnonExclusive(page)) { 1368 folio_unlock(folio); 1369 goto reuse; 1370 } 1371 1372 /* 1373 * See do_wp_page(): we can only reuse the folio exclusively if 1374 * there are no additional references. Note that we always drain 1375 * the LRU cache immediately after adding a THP. 1376 */ 1377 if (folio_ref_count(folio) > 1378 1 + folio_test_swapcache(folio) * folio_nr_pages(folio)) 1379 goto unlock_fallback; 1380 if (folio_test_swapcache(folio)) 1381 folio_free_swap(folio); 1382 if (folio_ref_count(folio) == 1) { 1383 pmd_t entry; 1384 1385 folio_move_anon_rmap(folio, vma); 1386 SetPageAnonExclusive(page); 1387 folio_unlock(folio); 1388 reuse: 1389 if (unlikely(unshare)) { 1390 spin_unlock(vmf->ptl); 1391 return 0; 1392 } 1393 entry = pmd_mkyoung(orig_pmd); 1394 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1395 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1396 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1397 spin_unlock(vmf->ptl); 1398 return 0; 1399 } 1400 1401 unlock_fallback: 1402 folio_unlock(folio); 1403 spin_unlock(vmf->ptl); 1404 fallback: 1405 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1406 return VM_FAULT_FALLBACK; 1407 } 1408 1409 static inline bool can_change_pmd_writable(struct vm_area_struct *vma, 1410 unsigned long addr, pmd_t pmd) 1411 { 1412 struct page *page; 1413 1414 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) 1415 return false; 1416 1417 /* Don't touch entries that are not even readable (NUMA hinting). */ 1418 if (pmd_protnone(pmd)) 1419 return false; 1420 1421 /* Do we need write faults for softdirty tracking? */ 1422 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) 1423 return false; 1424 1425 /* Do we need write faults for uffd-wp tracking? */ 1426 if (userfaultfd_huge_pmd_wp(vma, pmd)) 1427 return false; 1428 1429 if (!(vma->vm_flags & VM_SHARED)) { 1430 /* See can_change_pte_writable(). */ 1431 page = vm_normal_page_pmd(vma, addr, pmd); 1432 return page && PageAnon(page) && PageAnonExclusive(page); 1433 } 1434 1435 /* See can_change_pte_writable(). */ 1436 return pmd_dirty(pmd); 1437 } 1438 1439 /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */ 1440 static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page, 1441 struct vm_area_struct *vma, 1442 unsigned int flags) 1443 { 1444 /* If the pmd is writable, we can write to the page. */ 1445 if (pmd_write(pmd)) 1446 return true; 1447 1448 /* Maybe FOLL_FORCE is set to override it? */ 1449 if (!(flags & FOLL_FORCE)) 1450 return false; 1451 1452 /* But FOLL_FORCE has no effect on shared mappings */ 1453 if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED)) 1454 return false; 1455 1456 /* ... or read-only private ones */ 1457 if (!(vma->vm_flags & VM_MAYWRITE)) 1458 return false; 1459 1460 /* ... or already writable ones that just need to take a write fault */ 1461 if (vma->vm_flags & VM_WRITE) 1462 return false; 1463 1464 /* 1465 * See can_change_pte_writable(): we broke COW and could map the page 1466 * writable if we have an exclusive anonymous page ... 1467 */ 1468 if (!page || !PageAnon(page) || !PageAnonExclusive(page)) 1469 return false; 1470 1471 /* ... and a write-fault isn't required for other reasons. */ 1472 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) 1473 return false; 1474 return !userfaultfd_huge_pmd_wp(vma, pmd); 1475 } 1476 1477 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1478 unsigned long addr, 1479 pmd_t *pmd, 1480 unsigned int flags) 1481 { 1482 struct mm_struct *mm = vma->vm_mm; 1483 struct page *page; 1484 int ret; 1485 1486 assert_spin_locked(pmd_lockptr(mm, pmd)); 1487 1488 page = pmd_page(*pmd); 1489 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1490 1491 if ((flags & FOLL_WRITE) && 1492 !can_follow_write_pmd(*pmd, page, vma, flags)) 1493 return NULL; 1494 1495 /* Avoid dumping huge zero page */ 1496 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1497 return ERR_PTR(-EFAULT); 1498 1499 if (pmd_protnone(*pmd) && !gup_can_follow_protnone(vma, flags)) 1500 return NULL; 1501 1502 if (!pmd_write(*pmd) && gup_must_unshare(vma, flags, page)) 1503 return ERR_PTR(-EMLINK); 1504 1505 VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) && 1506 !PageAnonExclusive(page), page); 1507 1508 ret = try_grab_page(page, flags); 1509 if (ret) 1510 return ERR_PTR(ret); 1511 1512 if (flags & FOLL_TOUCH) 1513 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1514 1515 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1516 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1517 1518 return page; 1519 } 1520 1521 /* NUMA hinting page fault entry point for trans huge pmds */ 1522 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) 1523 { 1524 struct vm_area_struct *vma = vmf->vma; 1525 pmd_t oldpmd = vmf->orig_pmd; 1526 pmd_t pmd; 1527 struct folio *folio; 1528 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1529 int nid = NUMA_NO_NODE; 1530 int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK); 1531 bool migrated = false, writable = false; 1532 int flags = 0; 1533 1534 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1535 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1536 spin_unlock(vmf->ptl); 1537 goto out; 1538 } 1539 1540 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1541 1542 /* 1543 * Detect now whether the PMD could be writable; this information 1544 * is only valid while holding the PT lock. 1545 */ 1546 writable = pmd_write(pmd); 1547 if (!writable && vma_wants_manual_pte_write_upgrade(vma) && 1548 can_change_pmd_writable(vma, vmf->address, pmd)) 1549 writable = true; 1550 1551 folio = vm_normal_folio_pmd(vma, haddr, pmd); 1552 if (!folio) 1553 goto out_map; 1554 1555 /* See similar comment in do_numa_page for explanation */ 1556 if (!writable) 1557 flags |= TNF_NO_GROUP; 1558 1559 nid = folio_nid(folio); 1560 /* 1561 * For memory tiering mode, cpupid of slow memory page is used 1562 * to record page access time. So use default value. 1563 */ 1564 if (node_is_toptier(nid)) 1565 last_cpupid = folio_last_cpupid(folio); 1566 target_nid = numa_migrate_prep(folio, vma, haddr, nid, &flags); 1567 if (target_nid == NUMA_NO_NODE) { 1568 folio_put(folio); 1569 goto out_map; 1570 } 1571 1572 spin_unlock(vmf->ptl); 1573 writable = false; 1574 1575 migrated = migrate_misplaced_folio(folio, vma, target_nid); 1576 if (migrated) { 1577 flags |= TNF_MIGRATED; 1578 nid = target_nid; 1579 } else { 1580 flags |= TNF_MIGRATE_FAIL; 1581 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1582 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1583 spin_unlock(vmf->ptl); 1584 goto out; 1585 } 1586 goto out_map; 1587 } 1588 1589 out: 1590 if (nid != NUMA_NO_NODE) 1591 task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags); 1592 1593 return 0; 1594 1595 out_map: 1596 /* Restore the PMD */ 1597 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1598 pmd = pmd_mkyoung(pmd); 1599 if (writable) 1600 pmd = pmd_mkwrite(pmd, vma); 1601 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1602 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1603 spin_unlock(vmf->ptl); 1604 goto out; 1605 } 1606 1607 /* 1608 * Return true if we do MADV_FREE successfully on entire pmd page. 1609 * Otherwise, return false. 1610 */ 1611 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1612 pmd_t *pmd, unsigned long addr, unsigned long next) 1613 { 1614 spinlock_t *ptl; 1615 pmd_t orig_pmd; 1616 struct folio *folio; 1617 struct mm_struct *mm = tlb->mm; 1618 bool ret = false; 1619 1620 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1621 1622 ptl = pmd_trans_huge_lock(pmd, vma); 1623 if (!ptl) 1624 goto out_unlocked; 1625 1626 orig_pmd = *pmd; 1627 if (is_huge_zero_pmd(orig_pmd)) 1628 goto out; 1629 1630 if (unlikely(!pmd_present(orig_pmd))) { 1631 VM_BUG_ON(thp_migration_supported() && 1632 !is_pmd_migration_entry(orig_pmd)); 1633 goto out; 1634 } 1635 1636 folio = pfn_folio(pmd_pfn(orig_pmd)); 1637 /* 1638 * If other processes are mapping this folio, we couldn't discard 1639 * the folio unless they all do MADV_FREE so let's skip the folio. 1640 */ 1641 if (folio_estimated_sharers(folio) != 1) 1642 goto out; 1643 1644 if (!folio_trylock(folio)) 1645 goto out; 1646 1647 /* 1648 * If user want to discard part-pages of THP, split it so MADV_FREE 1649 * will deactivate only them. 1650 */ 1651 if (next - addr != HPAGE_PMD_SIZE) { 1652 folio_get(folio); 1653 spin_unlock(ptl); 1654 split_folio(folio); 1655 folio_unlock(folio); 1656 folio_put(folio); 1657 goto out_unlocked; 1658 } 1659 1660 if (folio_test_dirty(folio)) 1661 folio_clear_dirty(folio); 1662 folio_unlock(folio); 1663 1664 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1665 pmdp_invalidate(vma, addr, pmd); 1666 orig_pmd = pmd_mkold(orig_pmd); 1667 orig_pmd = pmd_mkclean(orig_pmd); 1668 1669 set_pmd_at(mm, addr, pmd, orig_pmd); 1670 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1671 } 1672 1673 folio_mark_lazyfree(folio); 1674 ret = true; 1675 out: 1676 spin_unlock(ptl); 1677 out_unlocked: 1678 return ret; 1679 } 1680 1681 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1682 { 1683 pgtable_t pgtable; 1684 1685 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1686 pte_free(mm, pgtable); 1687 mm_dec_nr_ptes(mm); 1688 } 1689 1690 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1691 pmd_t *pmd, unsigned long addr) 1692 { 1693 pmd_t orig_pmd; 1694 spinlock_t *ptl; 1695 1696 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1697 1698 ptl = __pmd_trans_huge_lock(pmd, vma); 1699 if (!ptl) 1700 return 0; 1701 /* 1702 * For architectures like ppc64 we look at deposited pgtable 1703 * when calling pmdp_huge_get_and_clear. So do the 1704 * pgtable_trans_huge_withdraw after finishing pmdp related 1705 * operations. 1706 */ 1707 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1708 tlb->fullmm); 1709 arch_check_zapped_pmd(vma, orig_pmd); 1710 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1711 if (vma_is_special_huge(vma)) { 1712 if (arch_needs_pgtable_deposit()) 1713 zap_deposited_table(tlb->mm, pmd); 1714 spin_unlock(ptl); 1715 } else if (is_huge_zero_pmd(orig_pmd)) { 1716 zap_deposited_table(tlb->mm, pmd); 1717 spin_unlock(ptl); 1718 } else { 1719 struct page *page = NULL; 1720 int flush_needed = 1; 1721 1722 if (pmd_present(orig_pmd)) { 1723 page = pmd_page(orig_pmd); 1724 page_remove_rmap(page, vma, true); 1725 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1726 VM_BUG_ON_PAGE(!PageHead(page), page); 1727 } else if (thp_migration_supported()) { 1728 swp_entry_t entry; 1729 1730 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1731 entry = pmd_to_swp_entry(orig_pmd); 1732 page = pfn_swap_entry_to_page(entry); 1733 flush_needed = 0; 1734 } else 1735 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1736 1737 if (PageAnon(page)) { 1738 zap_deposited_table(tlb->mm, pmd); 1739 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1740 } else { 1741 if (arch_needs_pgtable_deposit()) 1742 zap_deposited_table(tlb->mm, pmd); 1743 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1744 } 1745 1746 spin_unlock(ptl); 1747 if (flush_needed) 1748 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1749 } 1750 return 1; 1751 } 1752 1753 #ifndef pmd_move_must_withdraw 1754 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1755 spinlock_t *old_pmd_ptl, 1756 struct vm_area_struct *vma) 1757 { 1758 /* 1759 * With split pmd lock we also need to move preallocated 1760 * PTE page table if new_pmd is on different PMD page table. 1761 * 1762 * We also don't deposit and withdraw tables for file pages. 1763 */ 1764 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1765 } 1766 #endif 1767 1768 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1769 { 1770 #ifdef CONFIG_MEM_SOFT_DIRTY 1771 if (unlikely(is_pmd_migration_entry(pmd))) 1772 pmd = pmd_swp_mksoft_dirty(pmd); 1773 else if (pmd_present(pmd)) 1774 pmd = pmd_mksoft_dirty(pmd); 1775 #endif 1776 return pmd; 1777 } 1778 1779 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1780 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1781 { 1782 spinlock_t *old_ptl, *new_ptl; 1783 pmd_t pmd; 1784 struct mm_struct *mm = vma->vm_mm; 1785 bool force_flush = false; 1786 1787 /* 1788 * The destination pmd shouldn't be established, free_pgtables() 1789 * should have released it; but move_page_tables() might have already 1790 * inserted a page table, if racing against shmem/file collapse. 1791 */ 1792 if (!pmd_none(*new_pmd)) { 1793 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1794 return false; 1795 } 1796 1797 /* 1798 * We don't have to worry about the ordering of src and dst 1799 * ptlocks because exclusive mmap_lock prevents deadlock. 1800 */ 1801 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1802 if (old_ptl) { 1803 new_ptl = pmd_lockptr(mm, new_pmd); 1804 if (new_ptl != old_ptl) 1805 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1806 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1807 if (pmd_present(pmd)) 1808 force_flush = true; 1809 VM_BUG_ON(!pmd_none(*new_pmd)); 1810 1811 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1812 pgtable_t pgtable; 1813 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1814 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1815 } 1816 pmd = move_soft_dirty_pmd(pmd); 1817 set_pmd_at(mm, new_addr, new_pmd, pmd); 1818 if (force_flush) 1819 flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1820 if (new_ptl != old_ptl) 1821 spin_unlock(new_ptl); 1822 spin_unlock(old_ptl); 1823 return true; 1824 } 1825 return false; 1826 } 1827 1828 /* 1829 * Returns 1830 * - 0 if PMD could not be locked 1831 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary 1832 * or if prot_numa but THP migration is not supported 1833 * - HPAGE_PMD_NR if protections changed and TLB flush necessary 1834 */ 1835 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1836 pmd_t *pmd, unsigned long addr, pgprot_t newprot, 1837 unsigned long cp_flags) 1838 { 1839 struct mm_struct *mm = vma->vm_mm; 1840 spinlock_t *ptl; 1841 pmd_t oldpmd, entry; 1842 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1843 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1844 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1845 int ret = 1; 1846 1847 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1848 1849 if (prot_numa && !thp_migration_supported()) 1850 return 1; 1851 1852 ptl = __pmd_trans_huge_lock(pmd, vma); 1853 if (!ptl) 1854 return 0; 1855 1856 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1857 if (is_swap_pmd(*pmd)) { 1858 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1859 struct folio *folio = page_folio(pfn_swap_entry_to_page(entry)); 1860 pmd_t newpmd; 1861 1862 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1863 if (is_writable_migration_entry(entry)) { 1864 /* 1865 * A protection check is difficult so 1866 * just be safe and disable write 1867 */ 1868 if (folio_test_anon(folio)) 1869 entry = make_readable_exclusive_migration_entry(swp_offset(entry)); 1870 else 1871 entry = make_readable_migration_entry(swp_offset(entry)); 1872 newpmd = swp_entry_to_pmd(entry); 1873 if (pmd_swp_soft_dirty(*pmd)) 1874 newpmd = pmd_swp_mksoft_dirty(newpmd); 1875 } else { 1876 newpmd = *pmd; 1877 } 1878 1879 if (uffd_wp) 1880 newpmd = pmd_swp_mkuffd_wp(newpmd); 1881 else if (uffd_wp_resolve) 1882 newpmd = pmd_swp_clear_uffd_wp(newpmd); 1883 if (!pmd_same(*pmd, newpmd)) 1884 set_pmd_at(mm, addr, pmd, newpmd); 1885 goto unlock; 1886 } 1887 #endif 1888 1889 if (prot_numa) { 1890 struct folio *folio; 1891 bool toptier; 1892 /* 1893 * Avoid trapping faults against the zero page. The read-only 1894 * data is likely to be read-cached on the local CPU and 1895 * local/remote hits to the zero page are not interesting. 1896 */ 1897 if (is_huge_zero_pmd(*pmd)) 1898 goto unlock; 1899 1900 if (pmd_protnone(*pmd)) 1901 goto unlock; 1902 1903 folio = page_folio(pmd_page(*pmd)); 1904 toptier = node_is_toptier(folio_nid(folio)); 1905 /* 1906 * Skip scanning top tier node if normal numa 1907 * balancing is disabled 1908 */ 1909 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 1910 toptier) 1911 goto unlock; 1912 1913 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING && 1914 !toptier) 1915 folio_xchg_access_time(folio, 1916 jiffies_to_msecs(jiffies)); 1917 } 1918 /* 1919 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 1920 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1921 * which is also under mmap_read_lock(mm): 1922 * 1923 * CPU0: CPU1: 1924 * change_huge_pmd(prot_numa=1) 1925 * pmdp_huge_get_and_clear_notify() 1926 * madvise_dontneed() 1927 * zap_pmd_range() 1928 * pmd_trans_huge(*pmd) == 0 (without ptl) 1929 * // skip the pmd 1930 * set_pmd_at(); 1931 * // pmd is re-established 1932 * 1933 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1934 * which may break userspace. 1935 * 1936 * pmdp_invalidate_ad() is required to make sure we don't miss 1937 * dirty/young flags set by hardware. 1938 */ 1939 oldpmd = pmdp_invalidate_ad(vma, addr, pmd); 1940 1941 entry = pmd_modify(oldpmd, newprot); 1942 if (uffd_wp) 1943 entry = pmd_mkuffd_wp(entry); 1944 else if (uffd_wp_resolve) 1945 /* 1946 * Leave the write bit to be handled by PF interrupt 1947 * handler, then things like COW could be properly 1948 * handled. 1949 */ 1950 entry = pmd_clear_uffd_wp(entry); 1951 1952 /* See change_pte_range(). */ 1953 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) && 1954 can_change_pmd_writable(vma, addr, entry)) 1955 entry = pmd_mkwrite(entry, vma); 1956 1957 ret = HPAGE_PMD_NR; 1958 set_pmd_at(mm, addr, pmd, entry); 1959 1960 if (huge_pmd_needs_flush(oldpmd, entry)) 1961 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); 1962 unlock: 1963 spin_unlock(ptl); 1964 return ret; 1965 } 1966 1967 /* 1968 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1969 * 1970 * Note that if it returns page table lock pointer, this routine returns without 1971 * unlocking page table lock. So callers must unlock it. 1972 */ 1973 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1974 { 1975 spinlock_t *ptl; 1976 ptl = pmd_lock(vma->vm_mm, pmd); 1977 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 1978 pmd_devmap(*pmd))) 1979 return ptl; 1980 spin_unlock(ptl); 1981 return NULL; 1982 } 1983 1984 /* 1985 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. 1986 * 1987 * Note that if it returns page table lock pointer, this routine returns without 1988 * unlocking page table lock. So callers must unlock it. 1989 */ 1990 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 1991 { 1992 spinlock_t *ptl; 1993 1994 ptl = pud_lock(vma->vm_mm, pud); 1995 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 1996 return ptl; 1997 spin_unlock(ptl); 1998 return NULL; 1999 } 2000 2001 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 2002 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 2003 pud_t *pud, unsigned long addr) 2004 { 2005 spinlock_t *ptl; 2006 2007 ptl = __pud_trans_huge_lock(pud, vma); 2008 if (!ptl) 2009 return 0; 2010 2011 pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm); 2012 tlb_remove_pud_tlb_entry(tlb, pud, addr); 2013 if (vma_is_special_huge(vma)) { 2014 spin_unlock(ptl); 2015 /* No zero page support yet */ 2016 } else { 2017 /* No support for anonymous PUD pages yet */ 2018 BUG(); 2019 } 2020 return 1; 2021 } 2022 2023 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 2024 unsigned long haddr) 2025 { 2026 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 2027 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2028 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 2029 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 2030 2031 count_vm_event(THP_SPLIT_PUD); 2032 2033 pudp_huge_clear_flush(vma, haddr, pud); 2034 } 2035 2036 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 2037 unsigned long address) 2038 { 2039 spinlock_t *ptl; 2040 struct mmu_notifier_range range; 2041 2042 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, 2043 address & HPAGE_PUD_MASK, 2044 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 2045 mmu_notifier_invalidate_range_start(&range); 2046 ptl = pud_lock(vma->vm_mm, pud); 2047 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 2048 goto out; 2049 __split_huge_pud_locked(vma, pud, range.start); 2050 2051 out: 2052 spin_unlock(ptl); 2053 mmu_notifier_invalidate_range_end(&range); 2054 } 2055 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 2056 2057 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2058 unsigned long haddr, pmd_t *pmd) 2059 { 2060 struct mm_struct *mm = vma->vm_mm; 2061 pgtable_t pgtable; 2062 pmd_t _pmd, old_pmd; 2063 unsigned long addr; 2064 pte_t *pte; 2065 int i; 2066 2067 /* 2068 * Leave pmd empty until pte is filled note that it is fine to delay 2069 * notification until mmu_notifier_invalidate_range_end() as we are 2070 * replacing a zero pmd write protected page with a zero pte write 2071 * protected page. 2072 * 2073 * See Documentation/mm/mmu_notifier.rst 2074 */ 2075 old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); 2076 2077 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2078 pmd_populate(mm, &_pmd, pgtable); 2079 2080 pte = pte_offset_map(&_pmd, haddr); 2081 VM_BUG_ON(!pte); 2082 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2083 pte_t entry; 2084 2085 entry = pfn_pte(my_zero_pfn(addr), vma->vm_page_prot); 2086 entry = pte_mkspecial(entry); 2087 if (pmd_uffd_wp(old_pmd)) 2088 entry = pte_mkuffd_wp(entry); 2089 VM_BUG_ON(!pte_none(ptep_get(pte))); 2090 set_pte_at(mm, addr, pte, entry); 2091 pte++; 2092 } 2093 pte_unmap(pte - 1); 2094 smp_wmb(); /* make pte visible before pmd */ 2095 pmd_populate(mm, pmd, pgtable); 2096 } 2097 2098 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2099 unsigned long haddr, bool freeze) 2100 { 2101 struct mm_struct *mm = vma->vm_mm; 2102 struct page *page; 2103 pgtable_t pgtable; 2104 pmd_t old_pmd, _pmd; 2105 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 2106 bool anon_exclusive = false, dirty = false; 2107 unsigned long addr; 2108 pte_t *pte; 2109 int i; 2110 2111 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2112 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2113 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2114 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2115 && !pmd_devmap(*pmd)); 2116 2117 count_vm_event(THP_SPLIT_PMD); 2118 2119 if (!vma_is_anonymous(vma)) { 2120 old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd); 2121 /* 2122 * We are going to unmap this huge page. So 2123 * just go ahead and zap it 2124 */ 2125 if (arch_needs_pgtable_deposit()) 2126 zap_deposited_table(mm, pmd); 2127 if (vma_is_special_huge(vma)) 2128 return; 2129 if (unlikely(is_pmd_migration_entry(old_pmd))) { 2130 swp_entry_t entry; 2131 2132 entry = pmd_to_swp_entry(old_pmd); 2133 page = pfn_swap_entry_to_page(entry); 2134 } else { 2135 page = pmd_page(old_pmd); 2136 if (!PageDirty(page) && pmd_dirty(old_pmd)) 2137 set_page_dirty(page); 2138 if (!PageReferenced(page) && pmd_young(old_pmd)) 2139 SetPageReferenced(page); 2140 page_remove_rmap(page, vma, true); 2141 put_page(page); 2142 } 2143 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2144 return; 2145 } 2146 2147 if (is_huge_zero_pmd(*pmd)) { 2148 /* 2149 * FIXME: Do we want to invalidate secondary mmu by calling 2150 * mmu_notifier_arch_invalidate_secondary_tlbs() see comments below 2151 * inside __split_huge_pmd() ? 2152 * 2153 * We are going from a zero huge page write protected to zero 2154 * small page also write protected so it does not seems useful 2155 * to invalidate secondary mmu at this time. 2156 */ 2157 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2158 } 2159 2160 /* 2161 * Up to this point the pmd is present and huge and userland has the 2162 * whole access to the hugepage during the split (which happens in 2163 * place). If we overwrite the pmd with the not-huge version pointing 2164 * to the pte here (which of course we could if all CPUs were bug 2165 * free), userland could trigger a small page size TLB miss on the 2166 * small sized TLB while the hugepage TLB entry is still established in 2167 * the huge TLB. Some CPU doesn't like that. 2168 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2169 * 383 on page 105. Intel should be safe but is also warns that it's 2170 * only safe if the permission and cache attributes of the two entries 2171 * loaded in the two TLB is identical (which should be the case here). 2172 * But it is generally safer to never allow small and huge TLB entries 2173 * for the same virtual address to be loaded simultaneously. So instead 2174 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2175 * current pmd notpresent (atomically because here the pmd_trans_huge 2176 * must remain set at all times on the pmd until the split is complete 2177 * for this pmd), then we flush the SMP TLB and finally we write the 2178 * non-huge version of the pmd entry with pmd_populate. 2179 */ 2180 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2181 2182 pmd_migration = is_pmd_migration_entry(old_pmd); 2183 if (unlikely(pmd_migration)) { 2184 swp_entry_t entry; 2185 2186 entry = pmd_to_swp_entry(old_pmd); 2187 page = pfn_swap_entry_to_page(entry); 2188 write = is_writable_migration_entry(entry); 2189 if (PageAnon(page)) 2190 anon_exclusive = is_readable_exclusive_migration_entry(entry); 2191 young = is_migration_entry_young(entry); 2192 dirty = is_migration_entry_dirty(entry); 2193 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2194 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2195 } else { 2196 page = pmd_page(old_pmd); 2197 if (pmd_dirty(old_pmd)) { 2198 dirty = true; 2199 SetPageDirty(page); 2200 } 2201 write = pmd_write(old_pmd); 2202 young = pmd_young(old_pmd); 2203 soft_dirty = pmd_soft_dirty(old_pmd); 2204 uffd_wp = pmd_uffd_wp(old_pmd); 2205 2206 VM_BUG_ON_PAGE(!page_count(page), page); 2207 2208 /* 2209 * Without "freeze", we'll simply split the PMD, propagating the 2210 * PageAnonExclusive() flag for each PTE by setting it for 2211 * each subpage -- no need to (temporarily) clear. 2212 * 2213 * With "freeze" we want to replace mapped pages by 2214 * migration entries right away. This is only possible if we 2215 * managed to clear PageAnonExclusive() -- see 2216 * set_pmd_migration_entry(). 2217 * 2218 * In case we cannot clear PageAnonExclusive(), split the PMD 2219 * only and let try_to_migrate_one() fail later. 2220 * 2221 * See page_try_share_anon_rmap(): invalidate PMD first. 2222 */ 2223 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 2224 if (freeze && anon_exclusive && page_try_share_anon_rmap(page)) 2225 freeze = false; 2226 if (!freeze) 2227 page_ref_add(page, HPAGE_PMD_NR - 1); 2228 } 2229 2230 /* 2231 * Withdraw the table only after we mark the pmd entry invalid. 2232 * This's critical for some architectures (Power). 2233 */ 2234 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2235 pmd_populate(mm, &_pmd, pgtable); 2236 2237 pte = pte_offset_map(&_pmd, haddr); 2238 VM_BUG_ON(!pte); 2239 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2240 pte_t entry; 2241 /* 2242 * Note that NUMA hinting access restrictions are not 2243 * transferred to avoid any possibility of altering 2244 * permissions across VMAs. 2245 */ 2246 if (freeze || pmd_migration) { 2247 swp_entry_t swp_entry; 2248 if (write) 2249 swp_entry = make_writable_migration_entry( 2250 page_to_pfn(page + i)); 2251 else if (anon_exclusive) 2252 swp_entry = make_readable_exclusive_migration_entry( 2253 page_to_pfn(page + i)); 2254 else 2255 swp_entry = make_readable_migration_entry( 2256 page_to_pfn(page + i)); 2257 if (young) 2258 swp_entry = make_migration_entry_young(swp_entry); 2259 if (dirty) 2260 swp_entry = make_migration_entry_dirty(swp_entry); 2261 entry = swp_entry_to_pte(swp_entry); 2262 if (soft_dirty) 2263 entry = pte_swp_mksoft_dirty(entry); 2264 if (uffd_wp) 2265 entry = pte_swp_mkuffd_wp(entry); 2266 } else { 2267 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2268 if (write) 2269 entry = pte_mkwrite(entry, vma); 2270 if (anon_exclusive) 2271 SetPageAnonExclusive(page + i); 2272 if (!young) 2273 entry = pte_mkold(entry); 2274 /* NOTE: this may set soft-dirty too on some archs */ 2275 if (dirty) 2276 entry = pte_mkdirty(entry); 2277 if (soft_dirty) 2278 entry = pte_mksoft_dirty(entry); 2279 if (uffd_wp) 2280 entry = pte_mkuffd_wp(entry); 2281 page_add_anon_rmap(page + i, vma, addr, RMAP_NONE); 2282 } 2283 VM_BUG_ON(!pte_none(ptep_get(pte))); 2284 set_pte_at(mm, addr, pte, entry); 2285 pte++; 2286 } 2287 pte_unmap(pte - 1); 2288 2289 if (!pmd_migration) 2290 page_remove_rmap(page, vma, true); 2291 if (freeze) 2292 put_page(page); 2293 2294 smp_wmb(); /* make pte visible before pmd */ 2295 pmd_populate(mm, pmd, pgtable); 2296 } 2297 2298 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2299 unsigned long address, bool freeze, struct folio *folio) 2300 { 2301 spinlock_t *ptl; 2302 struct mmu_notifier_range range; 2303 2304 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm, 2305 address & HPAGE_PMD_MASK, 2306 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2307 mmu_notifier_invalidate_range_start(&range); 2308 ptl = pmd_lock(vma->vm_mm, pmd); 2309 2310 /* 2311 * If caller asks to setup a migration entry, we need a folio to check 2312 * pmd against. Otherwise we can end up replacing wrong folio. 2313 */ 2314 VM_BUG_ON(freeze && !folio); 2315 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); 2316 2317 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || 2318 is_pmd_migration_entry(*pmd)) { 2319 /* 2320 * It's safe to call pmd_page when folio is set because it's 2321 * guaranteed that pmd is present. 2322 */ 2323 if (folio && folio != page_folio(pmd_page(*pmd))) 2324 goto out; 2325 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2326 } 2327 2328 out: 2329 spin_unlock(ptl); 2330 mmu_notifier_invalidate_range_end(&range); 2331 } 2332 2333 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2334 bool freeze, struct folio *folio) 2335 { 2336 pmd_t *pmd = mm_find_pmd(vma->vm_mm, address); 2337 2338 if (!pmd) 2339 return; 2340 2341 __split_huge_pmd(vma, pmd, address, freeze, folio); 2342 } 2343 2344 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) 2345 { 2346 /* 2347 * If the new address isn't hpage aligned and it could previously 2348 * contain an hugepage: check if we need to split an huge pmd. 2349 */ 2350 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && 2351 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), 2352 ALIGN(address, HPAGE_PMD_SIZE))) 2353 split_huge_pmd_address(vma, address, false, NULL); 2354 } 2355 2356 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2357 unsigned long start, 2358 unsigned long end, 2359 long adjust_next) 2360 { 2361 /* Check if we need to split start first. */ 2362 split_huge_pmd_if_needed(vma, start); 2363 2364 /* Check if we need to split end next. */ 2365 split_huge_pmd_if_needed(vma, end); 2366 2367 /* 2368 * If we're also updating the next vma vm_start, 2369 * check if we need to split it. 2370 */ 2371 if (adjust_next > 0) { 2372 struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end); 2373 unsigned long nstart = next->vm_start; 2374 nstart += adjust_next; 2375 split_huge_pmd_if_needed(next, nstart); 2376 } 2377 } 2378 2379 static void unmap_folio(struct folio *folio) 2380 { 2381 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | 2382 TTU_SYNC; 2383 2384 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 2385 2386 /* 2387 * Anon pages need migration entries to preserve them, but file 2388 * pages can simply be left unmapped, then faulted back on demand. 2389 * If that is ever changed (perhaps for mlock), update remap_page(). 2390 */ 2391 if (folio_test_anon(folio)) 2392 try_to_migrate(folio, ttu_flags); 2393 else 2394 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); 2395 } 2396 2397 static void remap_page(struct folio *folio, unsigned long nr) 2398 { 2399 int i = 0; 2400 2401 /* If unmap_folio() uses try_to_migrate() on file, remove this check */ 2402 if (!folio_test_anon(folio)) 2403 return; 2404 for (;;) { 2405 remove_migration_ptes(folio, folio, true); 2406 i += folio_nr_pages(folio); 2407 if (i >= nr) 2408 break; 2409 folio = folio_next(folio); 2410 } 2411 } 2412 2413 static void lru_add_page_tail(struct page *head, struct page *tail, 2414 struct lruvec *lruvec, struct list_head *list) 2415 { 2416 VM_BUG_ON_PAGE(!PageHead(head), head); 2417 VM_BUG_ON_PAGE(PageCompound(tail), head); 2418 VM_BUG_ON_PAGE(PageLRU(tail), head); 2419 lockdep_assert_held(&lruvec->lru_lock); 2420 2421 if (list) { 2422 /* page reclaim is reclaiming a huge page */ 2423 VM_WARN_ON(PageLRU(head)); 2424 get_page(tail); 2425 list_add_tail(&tail->lru, list); 2426 } else { 2427 /* head is still on lru (and we have it frozen) */ 2428 VM_WARN_ON(!PageLRU(head)); 2429 if (PageUnevictable(tail)) 2430 tail->mlock_count = 0; 2431 else 2432 list_add_tail(&tail->lru, &head->lru); 2433 SetPageLRU(tail); 2434 } 2435 } 2436 2437 static void __split_huge_page_tail(struct folio *folio, int tail, 2438 struct lruvec *lruvec, struct list_head *list) 2439 { 2440 struct page *head = &folio->page; 2441 struct page *page_tail = head + tail; 2442 /* 2443 * Careful: new_folio is not a "real" folio before we cleared PageTail. 2444 * Don't pass it around before clear_compound_head(). 2445 */ 2446 struct folio *new_folio = (struct folio *)page_tail; 2447 2448 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2449 2450 /* 2451 * Clone page flags before unfreezing refcount. 2452 * 2453 * After successful get_page_unless_zero() might follow flags change, 2454 * for example lock_page() which set PG_waiters. 2455 * 2456 * Note that for mapped sub-pages of an anonymous THP, 2457 * PG_anon_exclusive has been cleared in unmap_folio() and is stored in 2458 * the migration entry instead from where remap_page() will restore it. 2459 * We can still have PG_anon_exclusive set on effectively unmapped and 2460 * unreferenced sub-pages of an anonymous THP: we can simply drop 2461 * PG_anon_exclusive (-> PG_mappedtodisk) for these here. 2462 */ 2463 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2464 page_tail->flags |= (head->flags & 2465 ((1L << PG_referenced) | 2466 (1L << PG_swapbacked) | 2467 (1L << PG_swapcache) | 2468 (1L << PG_mlocked) | 2469 (1L << PG_uptodate) | 2470 (1L << PG_active) | 2471 (1L << PG_workingset) | 2472 (1L << PG_locked) | 2473 (1L << PG_unevictable) | 2474 #ifdef CONFIG_ARCH_USES_PG_ARCH_X 2475 (1L << PG_arch_2) | 2476 (1L << PG_arch_3) | 2477 #endif 2478 (1L << PG_dirty) | 2479 LRU_GEN_MASK | LRU_REFS_MASK)); 2480 2481 /* ->mapping in first and second tail page is replaced by other uses */ 2482 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2483 page_tail); 2484 page_tail->mapping = head->mapping; 2485 page_tail->index = head->index + tail; 2486 2487 /* 2488 * page->private should not be set in tail pages. Fix up and warn once 2489 * if private is unexpectedly set. 2490 */ 2491 if (unlikely(page_tail->private)) { 2492 VM_WARN_ON_ONCE_PAGE(true, page_tail); 2493 page_tail->private = 0; 2494 } 2495 if (folio_test_swapcache(folio)) 2496 new_folio->swap.val = folio->swap.val + tail; 2497 2498 /* Page flags must be visible before we make the page non-compound. */ 2499 smp_wmb(); 2500 2501 /* 2502 * Clear PageTail before unfreezing page refcount. 2503 * 2504 * After successful get_page_unless_zero() might follow put_page() 2505 * which needs correct compound_head(). 2506 */ 2507 clear_compound_head(page_tail); 2508 2509 /* Finally unfreeze refcount. Additional reference from page cache. */ 2510 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2511 PageSwapCache(head))); 2512 2513 if (page_is_young(head)) 2514 set_page_young(page_tail); 2515 if (page_is_idle(head)) 2516 set_page_idle(page_tail); 2517 2518 folio_xchg_last_cpupid(new_folio, folio_last_cpupid(folio)); 2519 2520 /* 2521 * always add to the tail because some iterators expect new 2522 * pages to show after the currently processed elements - e.g. 2523 * migrate_pages 2524 */ 2525 lru_add_page_tail(head, page_tail, lruvec, list); 2526 } 2527 2528 static void __split_huge_page(struct page *page, struct list_head *list, 2529 pgoff_t end) 2530 { 2531 struct folio *folio = page_folio(page); 2532 struct page *head = &folio->page; 2533 struct lruvec *lruvec; 2534 struct address_space *swap_cache = NULL; 2535 unsigned long offset = 0; 2536 unsigned int nr = thp_nr_pages(head); 2537 int i, nr_dropped = 0; 2538 2539 /* complete memcg works before add pages to LRU */ 2540 split_page_memcg(head, nr); 2541 2542 if (folio_test_anon(folio) && folio_test_swapcache(folio)) { 2543 offset = swp_offset(folio->swap); 2544 swap_cache = swap_address_space(folio->swap); 2545 xa_lock(&swap_cache->i_pages); 2546 } 2547 2548 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ 2549 lruvec = folio_lruvec_lock(folio); 2550 2551 ClearPageHasHWPoisoned(head); 2552 2553 for (i = nr - 1; i >= 1; i--) { 2554 __split_huge_page_tail(folio, i, lruvec, list); 2555 /* Some pages can be beyond EOF: drop them from page cache */ 2556 if (head[i].index >= end) { 2557 struct folio *tail = page_folio(head + i); 2558 2559 if (shmem_mapping(head->mapping)) 2560 nr_dropped++; 2561 else if (folio_test_clear_dirty(tail)) 2562 folio_account_cleaned(tail, 2563 inode_to_wb(folio->mapping->host)); 2564 __filemap_remove_folio(tail, NULL); 2565 folio_put(tail); 2566 } else if (!PageAnon(page)) { 2567 __xa_store(&head->mapping->i_pages, head[i].index, 2568 head + i, 0); 2569 } else if (swap_cache) { 2570 __xa_store(&swap_cache->i_pages, offset + i, 2571 head + i, 0); 2572 } 2573 } 2574 2575 ClearPageCompound(head); 2576 unlock_page_lruvec(lruvec); 2577 /* Caller disabled irqs, so they are still disabled here */ 2578 2579 split_page_owner(head, nr); 2580 2581 /* See comment in __split_huge_page_tail() */ 2582 if (PageAnon(head)) { 2583 /* Additional pin to swap cache */ 2584 if (PageSwapCache(head)) { 2585 page_ref_add(head, 2); 2586 xa_unlock(&swap_cache->i_pages); 2587 } else { 2588 page_ref_inc(head); 2589 } 2590 } else { 2591 /* Additional pin to page cache */ 2592 page_ref_add(head, 2); 2593 xa_unlock(&head->mapping->i_pages); 2594 } 2595 local_irq_enable(); 2596 2597 if (nr_dropped) 2598 shmem_uncharge(head->mapping->host, nr_dropped); 2599 remap_page(folio, nr); 2600 2601 if (folio_test_swapcache(folio)) 2602 split_swap_cluster(folio->swap); 2603 2604 for (i = 0; i < nr; i++) { 2605 struct page *subpage = head + i; 2606 if (subpage == page) 2607 continue; 2608 unlock_page(subpage); 2609 2610 /* 2611 * Subpages may be freed if there wasn't any mapping 2612 * like if add_to_swap() is running on a lru page that 2613 * had its mapping zapped. And freeing these pages 2614 * requires taking the lru_lock so we do the put_page 2615 * of the tail pages after the split is complete. 2616 */ 2617 free_page_and_swap_cache(subpage); 2618 } 2619 } 2620 2621 /* Racy check whether the huge page can be split */ 2622 bool can_split_folio(struct folio *folio, int *pextra_pins) 2623 { 2624 int extra_pins; 2625 2626 /* Additional pins from page cache */ 2627 if (folio_test_anon(folio)) 2628 extra_pins = folio_test_swapcache(folio) ? 2629 folio_nr_pages(folio) : 0; 2630 else 2631 extra_pins = folio_nr_pages(folio); 2632 if (pextra_pins) 2633 *pextra_pins = extra_pins; 2634 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1; 2635 } 2636 2637 /* 2638 * This function splits huge page into normal pages. @page can point to any 2639 * subpage of huge page to split. Split doesn't change the position of @page. 2640 * 2641 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2642 * The huge page must be locked. 2643 * 2644 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2645 * 2646 * Both head page and tail pages will inherit mapping, flags, and so on from 2647 * the hugepage. 2648 * 2649 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2650 * they are not mapped. 2651 * 2652 * Returns 0 if the hugepage is split successfully. 2653 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2654 * us. 2655 */ 2656 int split_huge_page_to_list(struct page *page, struct list_head *list) 2657 { 2658 struct folio *folio = page_folio(page); 2659 struct deferred_split *ds_queue = get_deferred_split_queue(folio); 2660 XA_STATE(xas, &folio->mapping->i_pages, folio->index); 2661 struct anon_vma *anon_vma = NULL; 2662 struct address_space *mapping = NULL; 2663 int extra_pins, ret; 2664 pgoff_t end; 2665 bool is_hzp; 2666 2667 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); 2668 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 2669 2670 is_hzp = is_huge_zero_page(&folio->page); 2671 if (is_hzp) { 2672 pr_warn_ratelimited("Called split_huge_page for huge zero page\n"); 2673 return -EBUSY; 2674 } 2675 2676 if (folio_test_writeback(folio)) 2677 return -EBUSY; 2678 2679 if (folio_test_anon(folio)) { 2680 /* 2681 * The caller does not necessarily hold an mmap_lock that would 2682 * prevent the anon_vma disappearing so we first we take a 2683 * reference to it and then lock the anon_vma for write. This 2684 * is similar to folio_lock_anon_vma_read except the write lock 2685 * is taken to serialise against parallel split or collapse 2686 * operations. 2687 */ 2688 anon_vma = folio_get_anon_vma(folio); 2689 if (!anon_vma) { 2690 ret = -EBUSY; 2691 goto out; 2692 } 2693 end = -1; 2694 mapping = NULL; 2695 anon_vma_lock_write(anon_vma); 2696 } else { 2697 gfp_t gfp; 2698 2699 mapping = folio->mapping; 2700 2701 /* Truncated ? */ 2702 if (!mapping) { 2703 ret = -EBUSY; 2704 goto out; 2705 } 2706 2707 gfp = current_gfp_context(mapping_gfp_mask(mapping) & 2708 GFP_RECLAIM_MASK); 2709 2710 if (!filemap_release_folio(folio, gfp)) { 2711 ret = -EBUSY; 2712 goto out; 2713 } 2714 2715 xas_split_alloc(&xas, folio, folio_order(folio), gfp); 2716 if (xas_error(&xas)) { 2717 ret = xas_error(&xas); 2718 goto out; 2719 } 2720 2721 anon_vma = NULL; 2722 i_mmap_lock_read(mapping); 2723 2724 /* 2725 *__split_huge_page() may need to trim off pages beyond EOF: 2726 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2727 * which cannot be nested inside the page tree lock. So note 2728 * end now: i_size itself may be changed at any moment, but 2729 * folio lock is good enough to serialize the trimming. 2730 */ 2731 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2732 if (shmem_mapping(mapping)) 2733 end = shmem_fallocend(mapping->host, end); 2734 } 2735 2736 /* 2737 * Racy check if we can split the page, before unmap_folio() will 2738 * split PMDs 2739 */ 2740 if (!can_split_folio(folio, &extra_pins)) { 2741 ret = -EAGAIN; 2742 goto out_unlock; 2743 } 2744 2745 unmap_folio(folio); 2746 2747 /* block interrupt reentry in xa_lock and spinlock */ 2748 local_irq_disable(); 2749 if (mapping) { 2750 /* 2751 * Check if the folio is present in page cache. 2752 * We assume all tail are present too, if folio is there. 2753 */ 2754 xas_lock(&xas); 2755 xas_reset(&xas); 2756 if (xas_load(&xas) != folio) 2757 goto fail; 2758 } 2759 2760 /* Prevent deferred_split_scan() touching ->_refcount */ 2761 spin_lock(&ds_queue->split_queue_lock); 2762 if (folio_ref_freeze(folio, 1 + extra_pins)) { 2763 if (!list_empty(&folio->_deferred_list)) { 2764 ds_queue->split_queue_len--; 2765 list_del(&folio->_deferred_list); 2766 } 2767 spin_unlock(&ds_queue->split_queue_lock); 2768 if (mapping) { 2769 int nr = folio_nr_pages(folio); 2770 2771 xas_split(&xas, folio, folio_order(folio)); 2772 if (folio_test_swapbacked(folio)) { 2773 __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, 2774 -nr); 2775 } else { 2776 __lruvec_stat_mod_folio(folio, NR_FILE_THPS, 2777 -nr); 2778 filemap_nr_thps_dec(mapping); 2779 } 2780 } 2781 2782 __split_huge_page(page, list, end); 2783 ret = 0; 2784 } else { 2785 spin_unlock(&ds_queue->split_queue_lock); 2786 fail: 2787 if (mapping) 2788 xas_unlock(&xas); 2789 local_irq_enable(); 2790 remap_page(folio, folio_nr_pages(folio)); 2791 ret = -EAGAIN; 2792 } 2793 2794 out_unlock: 2795 if (anon_vma) { 2796 anon_vma_unlock_write(anon_vma); 2797 put_anon_vma(anon_vma); 2798 } 2799 if (mapping) 2800 i_mmap_unlock_read(mapping); 2801 out: 2802 xas_destroy(&xas); 2803 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2804 return ret; 2805 } 2806 2807 void folio_undo_large_rmappable(struct folio *folio) 2808 { 2809 struct deferred_split *ds_queue; 2810 unsigned long flags; 2811 2812 /* 2813 * At this point, there is no one trying to add the folio to 2814 * deferred_list. If folio is not in deferred_list, it's safe 2815 * to check without acquiring the split_queue_lock. 2816 */ 2817 if (data_race(list_empty(&folio->_deferred_list))) 2818 return; 2819 2820 ds_queue = get_deferred_split_queue(folio); 2821 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2822 if (!list_empty(&folio->_deferred_list)) { 2823 ds_queue->split_queue_len--; 2824 list_del(&folio->_deferred_list); 2825 } 2826 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2827 } 2828 2829 void deferred_split_folio(struct folio *folio) 2830 { 2831 struct deferred_split *ds_queue = get_deferred_split_queue(folio); 2832 #ifdef CONFIG_MEMCG 2833 struct mem_cgroup *memcg = folio_memcg(folio); 2834 #endif 2835 unsigned long flags; 2836 2837 VM_BUG_ON_FOLIO(folio_order(folio) < 2, folio); 2838 2839 /* 2840 * The try_to_unmap() in page reclaim path might reach here too, 2841 * this may cause a race condition to corrupt deferred split queue. 2842 * And, if page reclaim is already handling the same folio, it is 2843 * unnecessary to handle it again in shrinker. 2844 * 2845 * Check the swapcache flag to determine if the folio is being 2846 * handled by page reclaim since THP swap would add the folio into 2847 * swap cache before calling try_to_unmap(). 2848 */ 2849 if (folio_test_swapcache(folio)) 2850 return; 2851 2852 if (!list_empty(&folio->_deferred_list)) 2853 return; 2854 2855 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2856 if (list_empty(&folio->_deferred_list)) { 2857 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2858 list_add_tail(&folio->_deferred_list, &ds_queue->split_queue); 2859 ds_queue->split_queue_len++; 2860 #ifdef CONFIG_MEMCG 2861 if (memcg) 2862 set_shrinker_bit(memcg, folio_nid(folio), 2863 deferred_split_shrinker->id); 2864 #endif 2865 } 2866 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2867 } 2868 2869 static unsigned long deferred_split_count(struct shrinker *shrink, 2870 struct shrink_control *sc) 2871 { 2872 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2873 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2874 2875 #ifdef CONFIG_MEMCG 2876 if (sc->memcg) 2877 ds_queue = &sc->memcg->deferred_split_queue; 2878 #endif 2879 return READ_ONCE(ds_queue->split_queue_len); 2880 } 2881 2882 static unsigned long deferred_split_scan(struct shrinker *shrink, 2883 struct shrink_control *sc) 2884 { 2885 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2886 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2887 unsigned long flags; 2888 LIST_HEAD(list); 2889 struct folio *folio, *next; 2890 int split = 0; 2891 2892 #ifdef CONFIG_MEMCG 2893 if (sc->memcg) 2894 ds_queue = &sc->memcg->deferred_split_queue; 2895 #endif 2896 2897 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2898 /* Take pin on all head pages to avoid freeing them under us */ 2899 list_for_each_entry_safe(folio, next, &ds_queue->split_queue, 2900 _deferred_list) { 2901 if (folio_try_get(folio)) { 2902 list_move(&folio->_deferred_list, &list); 2903 } else { 2904 /* We lost race with folio_put() */ 2905 list_del_init(&folio->_deferred_list); 2906 ds_queue->split_queue_len--; 2907 } 2908 if (!--sc->nr_to_scan) 2909 break; 2910 } 2911 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2912 2913 list_for_each_entry_safe(folio, next, &list, _deferred_list) { 2914 if (!folio_trylock(folio)) 2915 goto next; 2916 /* split_huge_page() removes page from list on success */ 2917 if (!split_folio(folio)) 2918 split++; 2919 folio_unlock(folio); 2920 next: 2921 folio_put(folio); 2922 } 2923 2924 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2925 list_splice_tail(&list, &ds_queue->split_queue); 2926 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2927 2928 /* 2929 * Stop shrinker if we didn't split any page, but the queue is empty. 2930 * This can happen if pages were freed under us. 2931 */ 2932 if (!split && list_empty(&ds_queue->split_queue)) 2933 return SHRINK_STOP; 2934 return split; 2935 } 2936 2937 #ifdef CONFIG_DEBUG_FS 2938 static void split_huge_pages_all(void) 2939 { 2940 struct zone *zone; 2941 struct page *page; 2942 struct folio *folio; 2943 unsigned long pfn, max_zone_pfn; 2944 unsigned long total = 0, split = 0; 2945 2946 pr_debug("Split all THPs\n"); 2947 for_each_zone(zone) { 2948 if (!managed_zone(zone)) 2949 continue; 2950 max_zone_pfn = zone_end_pfn(zone); 2951 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2952 int nr_pages; 2953 2954 page = pfn_to_online_page(pfn); 2955 if (!page || PageTail(page)) 2956 continue; 2957 folio = page_folio(page); 2958 if (!folio_try_get(folio)) 2959 continue; 2960 2961 if (unlikely(page_folio(page) != folio)) 2962 goto next; 2963 2964 if (zone != folio_zone(folio)) 2965 goto next; 2966 2967 if (!folio_test_large(folio) 2968 || folio_test_hugetlb(folio) 2969 || !folio_test_lru(folio)) 2970 goto next; 2971 2972 total++; 2973 folio_lock(folio); 2974 nr_pages = folio_nr_pages(folio); 2975 if (!split_folio(folio)) 2976 split++; 2977 pfn += nr_pages - 1; 2978 folio_unlock(folio); 2979 next: 2980 folio_put(folio); 2981 cond_resched(); 2982 } 2983 } 2984 2985 pr_debug("%lu of %lu THP split\n", split, total); 2986 } 2987 2988 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) 2989 { 2990 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || 2991 is_vm_hugetlb_page(vma); 2992 } 2993 2994 static int split_huge_pages_pid(int pid, unsigned long vaddr_start, 2995 unsigned long vaddr_end) 2996 { 2997 int ret = 0; 2998 struct task_struct *task; 2999 struct mm_struct *mm; 3000 unsigned long total = 0, split = 0; 3001 unsigned long addr; 3002 3003 vaddr_start &= PAGE_MASK; 3004 vaddr_end &= PAGE_MASK; 3005 3006 /* Find the task_struct from pid */ 3007 rcu_read_lock(); 3008 task = find_task_by_vpid(pid); 3009 if (!task) { 3010 rcu_read_unlock(); 3011 ret = -ESRCH; 3012 goto out; 3013 } 3014 get_task_struct(task); 3015 rcu_read_unlock(); 3016 3017 /* Find the mm_struct */ 3018 mm = get_task_mm(task); 3019 put_task_struct(task); 3020 3021 if (!mm) { 3022 ret = -EINVAL; 3023 goto out; 3024 } 3025 3026 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n", 3027 pid, vaddr_start, vaddr_end); 3028 3029 mmap_read_lock(mm); 3030 /* 3031 * always increase addr by PAGE_SIZE, since we could have a PTE page 3032 * table filled with PTE-mapped THPs, each of which is distinct. 3033 */ 3034 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { 3035 struct vm_area_struct *vma = vma_lookup(mm, addr); 3036 struct page *page; 3037 struct folio *folio; 3038 3039 if (!vma) 3040 break; 3041 3042 /* skip special VMA and hugetlb VMA */ 3043 if (vma_not_suitable_for_thp_split(vma)) { 3044 addr = vma->vm_end; 3045 continue; 3046 } 3047 3048 /* FOLL_DUMP to ignore special (like zero) pages */ 3049 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); 3050 3051 if (IS_ERR_OR_NULL(page)) 3052 continue; 3053 3054 folio = page_folio(page); 3055 if (!is_transparent_hugepage(folio)) 3056 goto next; 3057 3058 total++; 3059 if (!can_split_folio(folio, NULL)) 3060 goto next; 3061 3062 if (!folio_trylock(folio)) 3063 goto next; 3064 3065 if (!split_folio(folio)) 3066 split++; 3067 3068 folio_unlock(folio); 3069 next: 3070 folio_put(folio); 3071 cond_resched(); 3072 } 3073 mmap_read_unlock(mm); 3074 mmput(mm); 3075 3076 pr_debug("%lu of %lu THP split\n", split, total); 3077 3078 out: 3079 return ret; 3080 } 3081 3082 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, 3083 pgoff_t off_end) 3084 { 3085 struct filename *file; 3086 struct file *candidate; 3087 struct address_space *mapping; 3088 int ret = -EINVAL; 3089 pgoff_t index; 3090 int nr_pages = 1; 3091 unsigned long total = 0, split = 0; 3092 3093 file = getname_kernel(file_path); 3094 if (IS_ERR(file)) 3095 return ret; 3096 3097 candidate = file_open_name(file, O_RDONLY, 0); 3098 if (IS_ERR(candidate)) 3099 goto out; 3100 3101 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", 3102 file_path, off_start, off_end); 3103 3104 mapping = candidate->f_mapping; 3105 3106 for (index = off_start; index < off_end; index += nr_pages) { 3107 struct folio *folio = filemap_get_folio(mapping, index); 3108 3109 nr_pages = 1; 3110 if (IS_ERR(folio)) 3111 continue; 3112 3113 if (!folio_test_large(folio)) 3114 goto next; 3115 3116 total++; 3117 nr_pages = folio_nr_pages(folio); 3118 3119 if (!folio_trylock(folio)) 3120 goto next; 3121 3122 if (!split_folio(folio)) 3123 split++; 3124 3125 folio_unlock(folio); 3126 next: 3127 folio_put(folio); 3128 cond_resched(); 3129 } 3130 3131 filp_close(candidate, NULL); 3132 ret = 0; 3133 3134 pr_debug("%lu of %lu file-backed THP split\n", split, total); 3135 out: 3136 putname(file); 3137 return ret; 3138 } 3139 3140 #define MAX_INPUT_BUF_SZ 255 3141 3142 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, 3143 size_t count, loff_t *ppops) 3144 { 3145 static DEFINE_MUTEX(split_debug_mutex); 3146 ssize_t ret; 3147 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */ 3148 char input_buf[MAX_INPUT_BUF_SZ]; 3149 int pid; 3150 unsigned long vaddr_start, vaddr_end; 3151 3152 ret = mutex_lock_interruptible(&split_debug_mutex); 3153 if (ret) 3154 return ret; 3155 3156 ret = -EFAULT; 3157 3158 memset(input_buf, 0, MAX_INPUT_BUF_SZ); 3159 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) 3160 goto out; 3161 3162 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; 3163 3164 if (input_buf[0] == '/') { 3165 char *tok; 3166 char *buf = input_buf; 3167 char file_path[MAX_INPUT_BUF_SZ]; 3168 pgoff_t off_start = 0, off_end = 0; 3169 size_t input_len = strlen(input_buf); 3170 3171 tok = strsep(&buf, ","); 3172 if (tok) { 3173 strcpy(file_path, tok); 3174 } else { 3175 ret = -EINVAL; 3176 goto out; 3177 } 3178 3179 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end); 3180 if (ret != 2) { 3181 ret = -EINVAL; 3182 goto out; 3183 } 3184 ret = split_huge_pages_in_file(file_path, off_start, off_end); 3185 if (!ret) 3186 ret = input_len; 3187 3188 goto out; 3189 } 3190 3191 ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end); 3192 if (ret == 1 && pid == 1) { 3193 split_huge_pages_all(); 3194 ret = strlen(input_buf); 3195 goto out; 3196 } else if (ret != 3) { 3197 ret = -EINVAL; 3198 goto out; 3199 } 3200 3201 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end); 3202 if (!ret) 3203 ret = strlen(input_buf); 3204 out: 3205 mutex_unlock(&split_debug_mutex); 3206 return ret; 3207 3208 } 3209 3210 static const struct file_operations split_huge_pages_fops = { 3211 .owner = THIS_MODULE, 3212 .write = split_huge_pages_write, 3213 .llseek = no_llseek, 3214 }; 3215 3216 static int __init split_huge_pages_debugfs(void) 3217 { 3218 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 3219 &split_huge_pages_fops); 3220 return 0; 3221 } 3222 late_initcall(split_huge_pages_debugfs); 3223 #endif 3224 3225 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 3226 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 3227 struct page *page) 3228 { 3229 struct vm_area_struct *vma = pvmw->vma; 3230 struct mm_struct *mm = vma->vm_mm; 3231 unsigned long address = pvmw->address; 3232 bool anon_exclusive; 3233 pmd_t pmdval; 3234 swp_entry_t entry; 3235 pmd_t pmdswp; 3236 3237 if (!(pvmw->pmd && !pvmw->pte)) 3238 return 0; 3239 3240 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 3241 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 3242 3243 /* See page_try_share_anon_rmap(): invalidate PMD first. */ 3244 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 3245 if (anon_exclusive && page_try_share_anon_rmap(page)) { 3246 set_pmd_at(mm, address, pvmw->pmd, pmdval); 3247 return -EBUSY; 3248 } 3249 3250 if (pmd_dirty(pmdval)) 3251 set_page_dirty(page); 3252 if (pmd_write(pmdval)) 3253 entry = make_writable_migration_entry(page_to_pfn(page)); 3254 else if (anon_exclusive) 3255 entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); 3256 else 3257 entry = make_readable_migration_entry(page_to_pfn(page)); 3258 if (pmd_young(pmdval)) 3259 entry = make_migration_entry_young(entry); 3260 if (pmd_dirty(pmdval)) 3261 entry = make_migration_entry_dirty(entry); 3262 pmdswp = swp_entry_to_pmd(entry); 3263 if (pmd_soft_dirty(pmdval)) 3264 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3265 if (pmd_uffd_wp(pmdval)) 3266 pmdswp = pmd_swp_mkuffd_wp(pmdswp); 3267 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3268 page_remove_rmap(page, vma, true); 3269 put_page(page); 3270 trace_set_migration_pmd(address, pmd_val(pmdswp)); 3271 3272 return 0; 3273 } 3274 3275 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3276 { 3277 struct vm_area_struct *vma = pvmw->vma; 3278 struct mm_struct *mm = vma->vm_mm; 3279 unsigned long address = pvmw->address; 3280 unsigned long haddr = address & HPAGE_PMD_MASK; 3281 pmd_t pmde; 3282 swp_entry_t entry; 3283 3284 if (!(pvmw->pmd && !pvmw->pte)) 3285 return; 3286 3287 entry = pmd_to_swp_entry(*pvmw->pmd); 3288 get_page(new); 3289 pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot)); 3290 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3291 pmde = pmd_mksoft_dirty(pmde); 3292 if (is_writable_migration_entry(entry)) 3293 pmde = pmd_mkwrite(pmde, vma); 3294 if (pmd_swp_uffd_wp(*pvmw->pmd)) 3295 pmde = pmd_mkuffd_wp(pmde); 3296 if (!is_migration_entry_young(entry)) 3297 pmde = pmd_mkold(pmde); 3298 /* NOTE: this may contain setting soft-dirty on some archs */ 3299 if (PageDirty(new) && is_migration_entry_dirty(entry)) 3300 pmde = pmd_mkdirty(pmde); 3301 3302 if (PageAnon(new)) { 3303 rmap_t rmap_flags = RMAP_COMPOUND; 3304 3305 if (!is_readable_migration_entry(entry)) 3306 rmap_flags |= RMAP_EXCLUSIVE; 3307 3308 page_add_anon_rmap(new, vma, haddr, rmap_flags); 3309 } else { 3310 page_add_file_rmap(new, vma, true); 3311 } 3312 VM_BUG_ON(pmd_write(pmde) && PageAnon(new) && !PageAnonExclusive(new)); 3313 set_pmd_at(mm, haddr, pvmw->pmd, pmde); 3314 3315 /* No need to invalidate - it was non-present before */ 3316 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3317 trace_remove_migration_pmd(address, pmd_val(pmde)); 3318 } 3319 #endif 3320