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