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_NEVER_DAX)) 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_huge_enabled(vma, !enforce_sysfs); 123 124 /* Enforce sysfs THP requirements as necessary */ 125 if (enforce_sysfs && 126 (!hugepage_flags_enabled() || (!(vm_flags & VM_HUGEPAGE) && 127 !hugepage_flags_always()))) 128 return false; 129 130 /* Only regular file is valid */ 131 if (!in_pf && file_thp_enabled(vma)) 132 return true; 133 134 if (!vma_is_anonymous(vma)) 135 return false; 136 137 if (vma_is_temporary_stack(vma)) 138 return false; 139 140 /* 141 * THPeligible bit of smaps should show 1 for proper VMAs even 142 * though anon_vma is not initialized yet. 143 * 144 * Allow page fault since anon_vma may be not initialized until 145 * the first page fault. 146 */ 147 if (!vma->anon_vma) 148 return (smaps || in_pf); 149 150 return true; 151 } 152 153 static bool get_huge_zero_page(void) 154 { 155 struct page *zero_page; 156 retry: 157 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 158 return true; 159 160 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 161 HPAGE_PMD_ORDER); 162 if (!zero_page) { 163 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 164 return false; 165 } 166 preempt_disable(); 167 if (cmpxchg(&huge_zero_page, NULL, zero_page)) { 168 preempt_enable(); 169 __free_pages(zero_page, compound_order(zero_page)); 170 goto retry; 171 } 172 WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page)); 173 174 /* We take additional reference here. It will be put back by shrinker */ 175 atomic_set(&huge_zero_refcount, 2); 176 preempt_enable(); 177 count_vm_event(THP_ZERO_PAGE_ALLOC); 178 return true; 179 } 180 181 static void put_huge_zero_page(void) 182 { 183 /* 184 * Counter should never go to zero here. Only shrinker can put 185 * last reference. 186 */ 187 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 188 } 189 190 struct page *mm_get_huge_zero_page(struct mm_struct *mm) 191 { 192 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 193 return READ_ONCE(huge_zero_page); 194 195 if (!get_huge_zero_page()) 196 return NULL; 197 198 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 199 put_huge_zero_page(); 200 201 return READ_ONCE(huge_zero_page); 202 } 203 204 void mm_put_huge_zero_page(struct mm_struct *mm) 205 { 206 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 207 put_huge_zero_page(); 208 } 209 210 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 211 struct shrink_control *sc) 212 { 213 /* we can free zero page only if last reference remains */ 214 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 215 } 216 217 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 218 struct shrink_control *sc) 219 { 220 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 221 struct page *zero_page = xchg(&huge_zero_page, NULL); 222 BUG_ON(zero_page == NULL); 223 WRITE_ONCE(huge_zero_pfn, ~0UL); 224 __free_pages(zero_page, compound_order(zero_page)); 225 return HPAGE_PMD_NR; 226 } 227 228 return 0; 229 } 230 231 static struct shrinker huge_zero_page_shrinker = { 232 .count_objects = shrink_huge_zero_page_count, 233 .scan_objects = shrink_huge_zero_page_scan, 234 .seeks = DEFAULT_SEEKS, 235 }; 236 237 #ifdef CONFIG_SYSFS 238 static ssize_t enabled_show(struct kobject *kobj, 239 struct kobj_attribute *attr, char *buf) 240 { 241 const char *output; 242 243 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 244 output = "[always] madvise never"; 245 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 246 &transparent_hugepage_flags)) 247 output = "always [madvise] never"; 248 else 249 output = "always madvise [never]"; 250 251 return sysfs_emit(buf, "%s\n", output); 252 } 253 254 static ssize_t enabled_store(struct kobject *kobj, 255 struct kobj_attribute *attr, 256 const char *buf, size_t count) 257 { 258 ssize_t ret = count; 259 260 if (sysfs_streq(buf, "always")) { 261 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 262 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 263 } else if (sysfs_streq(buf, "madvise")) { 264 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 265 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 266 } else if (sysfs_streq(buf, "never")) { 267 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 268 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 269 } else 270 ret = -EINVAL; 271 272 if (ret > 0) { 273 int err = start_stop_khugepaged(); 274 if (err) 275 ret = err; 276 } 277 return ret; 278 } 279 280 static struct kobj_attribute enabled_attr = __ATTR_RW(enabled); 281 282 ssize_t single_hugepage_flag_show(struct kobject *kobj, 283 struct kobj_attribute *attr, char *buf, 284 enum transparent_hugepage_flag flag) 285 { 286 return sysfs_emit(buf, "%d\n", 287 !!test_bit(flag, &transparent_hugepage_flags)); 288 } 289 290 ssize_t single_hugepage_flag_store(struct kobject *kobj, 291 struct kobj_attribute *attr, 292 const char *buf, size_t count, 293 enum transparent_hugepage_flag flag) 294 { 295 unsigned long value; 296 int ret; 297 298 ret = kstrtoul(buf, 10, &value); 299 if (ret < 0) 300 return ret; 301 if (value > 1) 302 return -EINVAL; 303 304 if (value) 305 set_bit(flag, &transparent_hugepage_flags); 306 else 307 clear_bit(flag, &transparent_hugepage_flags); 308 309 return count; 310 } 311 312 static ssize_t defrag_show(struct kobject *kobj, 313 struct kobj_attribute *attr, char *buf) 314 { 315 const char *output; 316 317 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 318 &transparent_hugepage_flags)) 319 output = "[always] defer defer+madvise madvise never"; 320 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 321 &transparent_hugepage_flags)) 322 output = "always [defer] defer+madvise madvise never"; 323 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 324 &transparent_hugepage_flags)) 325 output = "always defer [defer+madvise] madvise never"; 326 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 327 &transparent_hugepage_flags)) 328 output = "always defer defer+madvise [madvise] never"; 329 else 330 output = "always defer defer+madvise madvise [never]"; 331 332 return sysfs_emit(buf, "%s\n", output); 333 } 334 335 static ssize_t defrag_store(struct kobject *kobj, 336 struct kobj_attribute *attr, 337 const char *buf, size_t count) 338 { 339 if (sysfs_streq(buf, "always")) { 340 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 341 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 342 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 343 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 344 } else if (sysfs_streq(buf, "defer+madvise")) { 345 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 346 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 347 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 348 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 349 } else if (sysfs_streq(buf, "defer")) { 350 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 351 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 352 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 353 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 354 } else if (sysfs_streq(buf, "madvise")) { 355 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 356 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 357 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 358 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 359 } else if (sysfs_streq(buf, "never")) { 360 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 361 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 362 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 363 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 364 } else 365 return -EINVAL; 366 367 return count; 368 } 369 static struct kobj_attribute defrag_attr = __ATTR_RW(defrag); 370 371 static ssize_t use_zero_page_show(struct kobject *kobj, 372 struct kobj_attribute *attr, char *buf) 373 { 374 return single_hugepage_flag_show(kobj, attr, buf, 375 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 376 } 377 static ssize_t use_zero_page_store(struct kobject *kobj, 378 struct kobj_attribute *attr, const char *buf, size_t count) 379 { 380 return single_hugepage_flag_store(kobj, attr, buf, count, 381 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 382 } 383 static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page); 384 385 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 386 struct kobj_attribute *attr, char *buf) 387 { 388 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); 389 } 390 static struct kobj_attribute hpage_pmd_size_attr = 391 __ATTR_RO(hpage_pmd_size); 392 393 static struct attribute *hugepage_attr[] = { 394 &enabled_attr.attr, 395 &defrag_attr.attr, 396 &use_zero_page_attr.attr, 397 &hpage_pmd_size_attr.attr, 398 #ifdef CONFIG_SHMEM 399 &shmem_enabled_attr.attr, 400 #endif 401 NULL, 402 }; 403 404 static const struct attribute_group hugepage_attr_group = { 405 .attrs = hugepage_attr, 406 }; 407 408 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 409 { 410 int err; 411 412 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 413 if (unlikely(!*hugepage_kobj)) { 414 pr_err("failed to create transparent hugepage kobject\n"); 415 return -ENOMEM; 416 } 417 418 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 419 if (err) { 420 pr_err("failed to register transparent hugepage group\n"); 421 goto delete_obj; 422 } 423 424 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 425 if (err) { 426 pr_err("failed to register transparent hugepage group\n"); 427 goto remove_hp_group; 428 } 429 430 return 0; 431 432 remove_hp_group: 433 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 434 delete_obj: 435 kobject_put(*hugepage_kobj); 436 return err; 437 } 438 439 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 440 { 441 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 442 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 443 kobject_put(hugepage_kobj); 444 } 445 #else 446 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 447 { 448 return 0; 449 } 450 451 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 452 { 453 } 454 #endif /* CONFIG_SYSFS */ 455 456 static int __init hugepage_init(void) 457 { 458 int err; 459 struct kobject *hugepage_kobj; 460 461 if (!has_transparent_hugepage()) { 462 /* 463 * Hardware doesn't support hugepages, hence disable 464 * DAX PMD support. 465 */ 466 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX; 467 return -EINVAL; 468 } 469 470 /* 471 * hugepages can't be allocated by the buddy allocator 472 */ 473 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); 474 /* 475 * we use page->mapping and page->index in second tail page 476 * as list_head: assuming THP order >= 2 477 */ 478 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); 479 480 err = hugepage_init_sysfs(&hugepage_kobj); 481 if (err) 482 goto err_sysfs; 483 484 err = khugepaged_init(); 485 if (err) 486 goto err_slab; 487 488 err = register_shrinker(&huge_zero_page_shrinker, "thp-zero"); 489 if (err) 490 goto err_hzp_shrinker; 491 err = register_shrinker(&deferred_split_shrinker, "thp-deferred_split"); 492 if (err) 493 goto err_split_shrinker; 494 495 /* 496 * By default disable transparent hugepages on smaller systems, 497 * where the extra memory used could hurt more than TLB overhead 498 * is likely to save. The admin can still enable it through /sys. 499 */ 500 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 501 transparent_hugepage_flags = 0; 502 return 0; 503 } 504 505 err = start_stop_khugepaged(); 506 if (err) 507 goto err_khugepaged; 508 509 return 0; 510 err_khugepaged: 511 unregister_shrinker(&deferred_split_shrinker); 512 err_split_shrinker: 513 unregister_shrinker(&huge_zero_page_shrinker); 514 err_hzp_shrinker: 515 khugepaged_destroy(); 516 err_slab: 517 hugepage_exit_sysfs(hugepage_kobj); 518 err_sysfs: 519 return err; 520 } 521 subsys_initcall(hugepage_init); 522 523 static int __init setup_transparent_hugepage(char *str) 524 { 525 int ret = 0; 526 if (!str) 527 goto out; 528 if (!strcmp(str, "always")) { 529 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 530 &transparent_hugepage_flags); 531 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 532 &transparent_hugepage_flags); 533 ret = 1; 534 } else if (!strcmp(str, "madvise")) { 535 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 536 &transparent_hugepage_flags); 537 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 538 &transparent_hugepage_flags); 539 ret = 1; 540 } else if (!strcmp(str, "never")) { 541 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 542 &transparent_hugepage_flags); 543 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 544 &transparent_hugepage_flags); 545 ret = 1; 546 } 547 out: 548 if (!ret) 549 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 550 return ret; 551 } 552 __setup("transparent_hugepage=", setup_transparent_hugepage); 553 554 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 555 { 556 if (likely(vma->vm_flags & VM_WRITE)) 557 pmd = pmd_mkwrite(pmd); 558 return pmd; 559 } 560 561 #ifdef CONFIG_MEMCG 562 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 563 { 564 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 565 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 566 567 if (memcg) 568 return &memcg->deferred_split_queue; 569 else 570 return &pgdat->deferred_split_queue; 571 } 572 #else 573 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 574 { 575 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 576 577 return &pgdat->deferred_split_queue; 578 } 579 #endif 580 581 void prep_transhuge_page(struct page *page) 582 { 583 /* 584 * we use page->mapping and page->index in second tail page 585 * as list_head: assuming THP order >= 2 586 */ 587 588 INIT_LIST_HEAD(page_deferred_list(page)); 589 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); 590 } 591 592 static inline bool is_transparent_hugepage(struct page *page) 593 { 594 if (!PageCompound(page)) 595 return false; 596 597 page = compound_head(page); 598 return is_huge_zero_page(page) || 599 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR; 600 } 601 602 static unsigned long __thp_get_unmapped_area(struct file *filp, 603 unsigned long addr, unsigned long len, 604 loff_t off, unsigned long flags, unsigned long size) 605 { 606 loff_t off_end = off + len; 607 loff_t off_align = round_up(off, size); 608 unsigned long len_pad, ret; 609 610 if (off_end <= off_align || (off_end - off_align) < size) 611 return 0; 612 613 len_pad = len + size; 614 if (len_pad < len || (off + len_pad) < off) 615 return 0; 616 617 ret = current->mm->get_unmapped_area(filp, addr, len_pad, 618 off >> PAGE_SHIFT, flags); 619 620 /* 621 * The failure might be due to length padding. The caller will retry 622 * without the padding. 623 */ 624 if (IS_ERR_VALUE(ret)) 625 return 0; 626 627 /* 628 * Do not try to align to THP boundary if allocation at the address 629 * hint succeeds. 630 */ 631 if (ret == addr) 632 return addr; 633 634 ret += (off - ret) & (size - 1); 635 return ret; 636 } 637 638 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 639 unsigned long len, unsigned long pgoff, unsigned long flags) 640 { 641 unsigned long ret; 642 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 643 644 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE); 645 if (ret) 646 return ret; 647 648 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 649 } 650 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 651 652 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 653 struct page *page, gfp_t gfp) 654 { 655 struct vm_area_struct *vma = vmf->vma; 656 pgtable_t pgtable; 657 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 658 vm_fault_t ret = 0; 659 660 VM_BUG_ON_PAGE(!PageCompound(page), page); 661 662 if (mem_cgroup_charge(page_folio(page), vma->vm_mm, gfp)) { 663 put_page(page); 664 count_vm_event(THP_FAULT_FALLBACK); 665 count_vm_event(THP_FAULT_FALLBACK_CHARGE); 666 return VM_FAULT_FALLBACK; 667 } 668 cgroup_throttle_swaprate(page, 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 __SetPageUptodate makes sure that 679 * clear_huge_page writes become visible before the set_pmd_at() 680 * write. 681 */ 682 __SetPageUptodate(page); 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 put_page(page); 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 page_add_new_anon_rmap(page, vma, haddr); 707 lru_cache_add_inactive_or_unevictable(page, 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 put_page(page); 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_prot - insert a pmd size pfn 889 * @vmf: Structure describing the fault 890 * @pfn: pfn to insert 891 * @pgprot: page protection to use 892 * @write: whether it's a write fault 893 * 894 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and 895 * also consult the vmf_insert_mixed_prot() documentation when 896 * @pgprot != @vmf->vma->vm_page_prot. 897 * 898 * Return: vm_fault_t value. 899 */ 900 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn, 901 pgprot_t pgprot, bool write) 902 { 903 unsigned long addr = vmf->address & PMD_MASK; 904 struct vm_area_struct *vma = vmf->vma; 905 pgtable_t pgtable = NULL; 906 907 /* 908 * If we had pmd_special, we could avoid all these restrictions, 909 * but we need to be consistent with PTEs and architectures that 910 * can't support a 'special' bit. 911 */ 912 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 913 !pfn_t_devmap(pfn)); 914 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 915 (VM_PFNMAP|VM_MIXEDMAP)); 916 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 917 918 if (addr < vma->vm_start || addr >= vma->vm_end) 919 return VM_FAULT_SIGBUS; 920 921 if (arch_needs_pgtable_deposit()) { 922 pgtable = pte_alloc_one(vma->vm_mm); 923 if (!pgtable) 924 return VM_FAULT_OOM; 925 } 926 927 track_pfn_insert(vma, &pgprot, pfn); 928 929 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 930 return VM_FAULT_NOPAGE; 931 } 932 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot); 933 934 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 935 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 936 { 937 if (likely(vma->vm_flags & VM_WRITE)) 938 pud = pud_mkwrite(pud); 939 return pud; 940 } 941 942 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 943 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) 944 { 945 struct mm_struct *mm = vma->vm_mm; 946 pud_t entry; 947 spinlock_t *ptl; 948 949 ptl = pud_lock(mm, pud); 950 if (!pud_none(*pud)) { 951 if (write) { 952 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 953 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 954 goto out_unlock; 955 } 956 entry = pud_mkyoung(*pud); 957 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 958 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 959 update_mmu_cache_pud(vma, addr, pud); 960 } 961 goto out_unlock; 962 } 963 964 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 965 if (pfn_t_devmap(pfn)) 966 entry = pud_mkdevmap(entry); 967 if (write) { 968 entry = pud_mkyoung(pud_mkdirty(entry)); 969 entry = maybe_pud_mkwrite(entry, vma); 970 } 971 set_pud_at(mm, addr, pud, entry); 972 update_mmu_cache_pud(vma, addr, pud); 973 974 out_unlock: 975 spin_unlock(ptl); 976 } 977 978 /** 979 * vmf_insert_pfn_pud_prot - insert a pud size pfn 980 * @vmf: Structure describing the fault 981 * @pfn: pfn to insert 982 * @pgprot: page protection to use 983 * @write: whether it's a write fault 984 * 985 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and 986 * also consult the vmf_insert_mixed_prot() documentation when 987 * @pgprot != @vmf->vma->vm_page_prot. 988 * 989 * Return: vm_fault_t value. 990 */ 991 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn, 992 pgprot_t pgprot, bool write) 993 { 994 unsigned long addr = vmf->address & PUD_MASK; 995 struct vm_area_struct *vma = vmf->vma; 996 997 /* 998 * If we had pud_special, we could avoid all these restrictions, 999 * but we need to be consistent with PTEs and architectures that 1000 * can't support a 'special' bit. 1001 */ 1002 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 1003 !pfn_t_devmap(pfn)); 1004 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1005 (VM_PFNMAP|VM_MIXEDMAP)); 1006 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1007 1008 if (addr < vma->vm_start || addr >= vma->vm_end) 1009 return VM_FAULT_SIGBUS; 1010 1011 track_pfn_insert(vma, &pgprot, pfn); 1012 1013 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); 1014 return VM_FAULT_NOPAGE; 1015 } 1016 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot); 1017 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1018 1019 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 1020 pmd_t *pmd, bool write) 1021 { 1022 pmd_t _pmd; 1023 1024 _pmd = pmd_mkyoung(*pmd); 1025 if (write) 1026 _pmd = pmd_mkdirty(_pmd); 1027 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 1028 pmd, _pmd, write)) 1029 update_mmu_cache_pmd(vma, addr, pmd); 1030 } 1031 1032 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 1033 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 1034 { 1035 unsigned long pfn = pmd_pfn(*pmd); 1036 struct mm_struct *mm = vma->vm_mm; 1037 struct page *page; 1038 int ret; 1039 1040 assert_spin_locked(pmd_lockptr(mm, pmd)); 1041 1042 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1043 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1044 (FOLL_PIN | FOLL_GET))) 1045 return NULL; 1046 1047 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 1048 return NULL; 1049 1050 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 1051 /* pass */; 1052 else 1053 return NULL; 1054 1055 if (flags & FOLL_TOUCH) 1056 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1057 1058 /* 1059 * device mapped pages can only be returned if the 1060 * caller will manage the page reference count. 1061 */ 1062 if (!(flags & (FOLL_GET | FOLL_PIN))) 1063 return ERR_PTR(-EEXIST); 1064 1065 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 1066 *pgmap = get_dev_pagemap(pfn, *pgmap); 1067 if (!*pgmap) 1068 return ERR_PTR(-EFAULT); 1069 page = pfn_to_page(pfn); 1070 ret = try_grab_page(page, flags); 1071 if (ret) 1072 page = ERR_PTR(ret); 1073 1074 return page; 1075 } 1076 1077 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1078 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1079 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) 1080 { 1081 spinlock_t *dst_ptl, *src_ptl; 1082 struct page *src_page; 1083 pmd_t pmd; 1084 pgtable_t pgtable = NULL; 1085 int ret = -ENOMEM; 1086 1087 /* Skip if can be re-fill on fault */ 1088 if (!vma_is_anonymous(dst_vma)) 1089 return 0; 1090 1091 pgtable = pte_alloc_one(dst_mm); 1092 if (unlikely(!pgtable)) 1093 goto out; 1094 1095 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1096 src_ptl = pmd_lockptr(src_mm, src_pmd); 1097 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1098 1099 ret = -EAGAIN; 1100 pmd = *src_pmd; 1101 1102 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1103 if (unlikely(is_swap_pmd(pmd))) { 1104 swp_entry_t entry = pmd_to_swp_entry(pmd); 1105 1106 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1107 if (!is_readable_migration_entry(entry)) { 1108 entry = make_readable_migration_entry( 1109 swp_offset(entry)); 1110 pmd = swp_entry_to_pmd(entry); 1111 if (pmd_swp_soft_dirty(*src_pmd)) 1112 pmd = pmd_swp_mksoft_dirty(pmd); 1113 if (pmd_swp_uffd_wp(*src_pmd)) 1114 pmd = pmd_swp_mkuffd_wp(pmd); 1115 set_pmd_at(src_mm, addr, src_pmd, pmd); 1116 } 1117 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1118 mm_inc_nr_ptes(dst_mm); 1119 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1120 if (!userfaultfd_wp(dst_vma)) 1121 pmd = pmd_swp_clear_uffd_wp(pmd); 1122 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1123 ret = 0; 1124 goto out_unlock; 1125 } 1126 #endif 1127 1128 if (unlikely(!pmd_trans_huge(pmd))) { 1129 pte_free(dst_mm, pgtable); 1130 goto out_unlock; 1131 } 1132 /* 1133 * When page table lock is held, the huge zero pmd should not be 1134 * under splitting since we don't split the page itself, only pmd to 1135 * a page table. 1136 */ 1137 if (is_huge_zero_pmd(pmd)) { 1138 /* 1139 * get_huge_zero_page() will never allocate a new page here, 1140 * since we already have a zero page to copy. It just takes a 1141 * reference. 1142 */ 1143 mm_get_huge_zero_page(dst_mm); 1144 goto out_zero_page; 1145 } 1146 1147 src_page = pmd_page(pmd); 1148 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1149 1150 get_page(src_page); 1151 if (unlikely(page_try_dup_anon_rmap(src_page, true, src_vma))) { 1152 /* Page maybe pinned: split and retry the fault on PTEs. */ 1153 put_page(src_page); 1154 pte_free(dst_mm, pgtable); 1155 spin_unlock(src_ptl); 1156 spin_unlock(dst_ptl); 1157 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); 1158 return -EAGAIN; 1159 } 1160 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1161 out_zero_page: 1162 mm_inc_nr_ptes(dst_mm); 1163 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1164 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1165 if (!userfaultfd_wp(dst_vma)) 1166 pmd = pmd_clear_uffd_wp(pmd); 1167 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1168 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1169 1170 ret = 0; 1171 out_unlock: 1172 spin_unlock(src_ptl); 1173 spin_unlock(dst_ptl); 1174 out: 1175 return ret; 1176 } 1177 1178 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1179 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1180 pud_t *pud, bool write) 1181 { 1182 pud_t _pud; 1183 1184 _pud = pud_mkyoung(*pud); 1185 if (write) 1186 _pud = pud_mkdirty(_pud); 1187 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1188 pud, _pud, write)) 1189 update_mmu_cache_pud(vma, addr, pud); 1190 } 1191 1192 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1193 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1194 { 1195 unsigned long pfn = pud_pfn(*pud); 1196 struct mm_struct *mm = vma->vm_mm; 1197 struct page *page; 1198 int ret; 1199 1200 assert_spin_locked(pud_lockptr(mm, pud)); 1201 1202 if (flags & FOLL_WRITE && !pud_write(*pud)) 1203 return NULL; 1204 1205 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1206 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1207 (FOLL_PIN | FOLL_GET))) 1208 return NULL; 1209 1210 if (pud_present(*pud) && pud_devmap(*pud)) 1211 /* pass */; 1212 else 1213 return NULL; 1214 1215 if (flags & FOLL_TOUCH) 1216 touch_pud(vma, addr, pud, flags & FOLL_WRITE); 1217 1218 /* 1219 * device mapped pages can only be returned if the 1220 * caller will manage the page reference count. 1221 * 1222 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here: 1223 */ 1224 if (!(flags & (FOLL_GET | FOLL_PIN))) 1225 return ERR_PTR(-EEXIST); 1226 1227 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1228 *pgmap = get_dev_pagemap(pfn, *pgmap); 1229 if (!*pgmap) 1230 return ERR_PTR(-EFAULT); 1231 page = pfn_to_page(pfn); 1232 1233 ret = try_grab_page(page, flags); 1234 if (ret) 1235 page = ERR_PTR(ret); 1236 1237 return page; 1238 } 1239 1240 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1241 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1242 struct vm_area_struct *vma) 1243 { 1244 spinlock_t *dst_ptl, *src_ptl; 1245 pud_t pud; 1246 int ret; 1247 1248 dst_ptl = pud_lock(dst_mm, dst_pud); 1249 src_ptl = pud_lockptr(src_mm, src_pud); 1250 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1251 1252 ret = -EAGAIN; 1253 pud = *src_pud; 1254 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1255 goto out_unlock; 1256 1257 /* 1258 * When page table lock is held, the huge zero pud should not be 1259 * under splitting since we don't split the page itself, only pud to 1260 * a page table. 1261 */ 1262 if (is_huge_zero_pud(pud)) { 1263 /* No huge zero pud yet */ 1264 } 1265 1266 /* 1267 * TODO: once we support anonymous pages, use page_try_dup_anon_rmap() 1268 * and split if duplicating fails. 1269 */ 1270 pudp_set_wrprotect(src_mm, addr, src_pud); 1271 pud = pud_mkold(pud_wrprotect(pud)); 1272 set_pud_at(dst_mm, addr, dst_pud, pud); 1273 1274 ret = 0; 1275 out_unlock: 1276 spin_unlock(src_ptl); 1277 spin_unlock(dst_ptl); 1278 return ret; 1279 } 1280 1281 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1282 { 1283 bool write = vmf->flags & FAULT_FLAG_WRITE; 1284 1285 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1286 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1287 goto unlock; 1288 1289 touch_pud(vmf->vma, vmf->address, vmf->pud, write); 1290 unlock: 1291 spin_unlock(vmf->ptl); 1292 } 1293 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1294 1295 void huge_pmd_set_accessed(struct vm_fault *vmf) 1296 { 1297 bool write = vmf->flags & FAULT_FLAG_WRITE; 1298 1299 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1300 if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) 1301 goto unlock; 1302 1303 touch_pmd(vmf->vma, vmf->address, vmf->pmd, write); 1304 1305 unlock: 1306 spin_unlock(vmf->ptl); 1307 } 1308 1309 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) 1310 { 1311 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; 1312 struct vm_area_struct *vma = vmf->vma; 1313 struct folio *folio; 1314 struct page *page; 1315 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1316 pmd_t orig_pmd = vmf->orig_pmd; 1317 1318 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1319 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1320 1321 if (is_huge_zero_pmd(orig_pmd)) 1322 goto fallback; 1323 1324 spin_lock(vmf->ptl); 1325 1326 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1327 spin_unlock(vmf->ptl); 1328 return 0; 1329 } 1330 1331 page = pmd_page(orig_pmd); 1332 folio = page_folio(page); 1333 VM_BUG_ON_PAGE(!PageHead(page), page); 1334 1335 /* Early check when only holding the PT lock. */ 1336 if (PageAnonExclusive(page)) 1337 goto reuse; 1338 1339 if (!folio_trylock(folio)) { 1340 folio_get(folio); 1341 spin_unlock(vmf->ptl); 1342 folio_lock(folio); 1343 spin_lock(vmf->ptl); 1344 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1345 spin_unlock(vmf->ptl); 1346 folio_unlock(folio); 1347 folio_put(folio); 1348 return 0; 1349 } 1350 folio_put(folio); 1351 } 1352 1353 /* Recheck after temporarily dropping the PT lock. */ 1354 if (PageAnonExclusive(page)) { 1355 folio_unlock(folio); 1356 goto reuse; 1357 } 1358 1359 /* 1360 * See do_wp_page(): we can only reuse the folio exclusively if 1361 * there are no additional references. Note that we always drain 1362 * the LRU pagevecs immediately after adding a THP. 1363 */ 1364 if (folio_ref_count(folio) > 1365 1 + folio_test_swapcache(folio) * folio_nr_pages(folio)) 1366 goto unlock_fallback; 1367 if (folio_test_swapcache(folio)) 1368 folio_free_swap(folio); 1369 if (folio_ref_count(folio) == 1) { 1370 pmd_t entry; 1371 1372 page_move_anon_rmap(page, vma); 1373 folio_unlock(folio); 1374 reuse: 1375 if (unlikely(unshare)) { 1376 spin_unlock(vmf->ptl); 1377 return 0; 1378 } 1379 entry = pmd_mkyoung(orig_pmd); 1380 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1381 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1382 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1383 spin_unlock(vmf->ptl); 1384 return 0; 1385 } 1386 1387 unlock_fallback: 1388 folio_unlock(folio); 1389 spin_unlock(vmf->ptl); 1390 fallback: 1391 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1392 return VM_FAULT_FALLBACK; 1393 } 1394 1395 static inline bool can_change_pmd_writable(struct vm_area_struct *vma, 1396 unsigned long addr, pmd_t pmd) 1397 { 1398 struct page *page; 1399 1400 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) 1401 return false; 1402 1403 /* Don't touch entries that are not even readable (NUMA hinting). */ 1404 if (pmd_protnone(pmd)) 1405 return false; 1406 1407 /* Do we need write faults for softdirty tracking? */ 1408 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) 1409 return false; 1410 1411 /* Do we need write faults for uffd-wp tracking? */ 1412 if (userfaultfd_huge_pmd_wp(vma, pmd)) 1413 return false; 1414 1415 if (!(vma->vm_flags & VM_SHARED)) { 1416 /* See can_change_pte_writable(). */ 1417 page = vm_normal_page_pmd(vma, addr, pmd); 1418 return page && PageAnon(page) && PageAnonExclusive(page); 1419 } 1420 1421 /* See can_change_pte_writable(). */ 1422 return pmd_dirty(pmd); 1423 } 1424 1425 /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */ 1426 static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page, 1427 struct vm_area_struct *vma, 1428 unsigned int flags) 1429 { 1430 /* If the pmd is writable, we can write to the page. */ 1431 if (pmd_write(pmd)) 1432 return true; 1433 1434 /* Maybe FOLL_FORCE is set to override it? */ 1435 if (!(flags & FOLL_FORCE)) 1436 return false; 1437 1438 /* But FOLL_FORCE has no effect on shared mappings */ 1439 if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED)) 1440 return false; 1441 1442 /* ... or read-only private ones */ 1443 if (!(vma->vm_flags & VM_MAYWRITE)) 1444 return false; 1445 1446 /* ... or already writable ones that just need to take a write fault */ 1447 if (vma->vm_flags & VM_WRITE) 1448 return false; 1449 1450 /* 1451 * See can_change_pte_writable(): we broke COW and could map the page 1452 * writable if we have an exclusive anonymous page ... 1453 */ 1454 if (!page || !PageAnon(page) || !PageAnonExclusive(page)) 1455 return false; 1456 1457 /* ... and a write-fault isn't required for other reasons. */ 1458 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) 1459 return false; 1460 return !userfaultfd_huge_pmd_wp(vma, pmd); 1461 } 1462 1463 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1464 unsigned long addr, 1465 pmd_t *pmd, 1466 unsigned int flags) 1467 { 1468 struct mm_struct *mm = vma->vm_mm; 1469 struct page *page; 1470 int ret; 1471 1472 assert_spin_locked(pmd_lockptr(mm, pmd)); 1473 1474 page = pmd_page(*pmd); 1475 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1476 1477 if ((flags & FOLL_WRITE) && 1478 !can_follow_write_pmd(*pmd, page, vma, flags)) 1479 return NULL; 1480 1481 /* Avoid dumping huge zero page */ 1482 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1483 return ERR_PTR(-EFAULT); 1484 1485 /* Full NUMA hinting faults to serialise migration in fault paths */ 1486 if (pmd_protnone(*pmd) && !gup_can_follow_protnone(flags)) 1487 return NULL; 1488 1489 if (!pmd_write(*pmd) && gup_must_unshare(vma, flags, page)) 1490 return ERR_PTR(-EMLINK); 1491 1492 VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) && 1493 !PageAnonExclusive(page), page); 1494 1495 ret = try_grab_page(page, flags); 1496 if (ret) 1497 return ERR_PTR(ret); 1498 1499 if (flags & FOLL_TOUCH) 1500 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1501 1502 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1503 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1504 1505 return page; 1506 } 1507 1508 /* NUMA hinting page fault entry point for trans huge pmds */ 1509 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) 1510 { 1511 struct vm_area_struct *vma = vmf->vma; 1512 pmd_t oldpmd = vmf->orig_pmd; 1513 pmd_t pmd; 1514 struct page *page; 1515 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1516 int page_nid = NUMA_NO_NODE; 1517 int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK); 1518 bool migrated = false, writable = false; 1519 int flags = 0; 1520 1521 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1522 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1523 spin_unlock(vmf->ptl); 1524 goto out; 1525 } 1526 1527 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1528 1529 /* 1530 * Detect now whether the PMD could be writable; this information 1531 * is only valid while holding the PT lock. 1532 */ 1533 writable = pmd_write(pmd); 1534 if (!writable && vma_wants_manual_pte_write_upgrade(vma) && 1535 can_change_pmd_writable(vma, vmf->address, pmd)) 1536 writable = true; 1537 1538 page = vm_normal_page_pmd(vma, haddr, pmd); 1539 if (!page) 1540 goto out_map; 1541 1542 /* See similar comment in do_numa_page for explanation */ 1543 if (!writable) 1544 flags |= TNF_NO_GROUP; 1545 1546 page_nid = page_to_nid(page); 1547 /* 1548 * For memory tiering mode, cpupid of slow memory page is used 1549 * to record page access time. So use default value. 1550 */ 1551 if (node_is_toptier(page_nid)) 1552 last_cpupid = page_cpupid_last(page); 1553 target_nid = numa_migrate_prep(page, vma, haddr, page_nid, 1554 &flags); 1555 1556 if (target_nid == NUMA_NO_NODE) { 1557 put_page(page); 1558 goto out_map; 1559 } 1560 1561 spin_unlock(vmf->ptl); 1562 writable = false; 1563 1564 migrated = migrate_misplaced_page(page, vma, target_nid); 1565 if (migrated) { 1566 flags |= TNF_MIGRATED; 1567 page_nid = target_nid; 1568 } else { 1569 flags |= TNF_MIGRATE_FAIL; 1570 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1571 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1572 spin_unlock(vmf->ptl); 1573 goto out; 1574 } 1575 goto out_map; 1576 } 1577 1578 out: 1579 if (page_nid != NUMA_NO_NODE) 1580 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1581 flags); 1582 1583 return 0; 1584 1585 out_map: 1586 /* Restore the PMD */ 1587 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1588 pmd = pmd_mkyoung(pmd); 1589 if (writable) 1590 pmd = pmd_mkwrite(pmd); 1591 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1592 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1593 spin_unlock(vmf->ptl); 1594 goto out; 1595 } 1596 1597 /* 1598 * Return true if we do MADV_FREE successfully on entire pmd page. 1599 * Otherwise, return false. 1600 */ 1601 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1602 pmd_t *pmd, unsigned long addr, unsigned long next) 1603 { 1604 spinlock_t *ptl; 1605 pmd_t orig_pmd; 1606 struct folio *folio; 1607 struct mm_struct *mm = tlb->mm; 1608 bool ret = false; 1609 1610 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1611 1612 ptl = pmd_trans_huge_lock(pmd, vma); 1613 if (!ptl) 1614 goto out_unlocked; 1615 1616 orig_pmd = *pmd; 1617 if (is_huge_zero_pmd(orig_pmd)) 1618 goto out; 1619 1620 if (unlikely(!pmd_present(orig_pmd))) { 1621 VM_BUG_ON(thp_migration_supported() && 1622 !is_pmd_migration_entry(orig_pmd)); 1623 goto out; 1624 } 1625 1626 folio = pfn_folio(pmd_pfn(orig_pmd)); 1627 /* 1628 * If other processes are mapping this folio, we couldn't discard 1629 * the folio unless they all do MADV_FREE so let's skip the folio. 1630 */ 1631 if (folio_mapcount(folio) != 1) 1632 goto out; 1633 1634 if (!folio_trylock(folio)) 1635 goto out; 1636 1637 /* 1638 * If user want to discard part-pages of THP, split it so MADV_FREE 1639 * will deactivate only them. 1640 */ 1641 if (next - addr != HPAGE_PMD_SIZE) { 1642 folio_get(folio); 1643 spin_unlock(ptl); 1644 split_folio(folio); 1645 folio_unlock(folio); 1646 folio_put(folio); 1647 goto out_unlocked; 1648 } 1649 1650 if (folio_test_dirty(folio)) 1651 folio_clear_dirty(folio); 1652 folio_unlock(folio); 1653 1654 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1655 pmdp_invalidate(vma, addr, pmd); 1656 orig_pmd = pmd_mkold(orig_pmd); 1657 orig_pmd = pmd_mkclean(orig_pmd); 1658 1659 set_pmd_at(mm, addr, pmd, orig_pmd); 1660 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1661 } 1662 1663 folio_mark_lazyfree(folio); 1664 ret = true; 1665 out: 1666 spin_unlock(ptl); 1667 out_unlocked: 1668 return ret; 1669 } 1670 1671 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1672 { 1673 pgtable_t pgtable; 1674 1675 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1676 pte_free(mm, pgtable); 1677 mm_dec_nr_ptes(mm); 1678 } 1679 1680 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1681 pmd_t *pmd, unsigned long addr) 1682 { 1683 pmd_t orig_pmd; 1684 spinlock_t *ptl; 1685 1686 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1687 1688 ptl = __pmd_trans_huge_lock(pmd, vma); 1689 if (!ptl) 1690 return 0; 1691 /* 1692 * For architectures like ppc64 we look at deposited pgtable 1693 * when calling pmdp_huge_get_and_clear. So do the 1694 * pgtable_trans_huge_withdraw after finishing pmdp related 1695 * operations. 1696 */ 1697 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1698 tlb->fullmm); 1699 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1700 if (vma_is_special_huge(vma)) { 1701 if (arch_needs_pgtable_deposit()) 1702 zap_deposited_table(tlb->mm, pmd); 1703 spin_unlock(ptl); 1704 } else if (is_huge_zero_pmd(orig_pmd)) { 1705 zap_deposited_table(tlb->mm, pmd); 1706 spin_unlock(ptl); 1707 } else { 1708 struct page *page = NULL; 1709 int flush_needed = 1; 1710 1711 if (pmd_present(orig_pmd)) { 1712 page = pmd_page(orig_pmd); 1713 page_remove_rmap(page, vma, true); 1714 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1715 VM_BUG_ON_PAGE(!PageHead(page), page); 1716 } else if (thp_migration_supported()) { 1717 swp_entry_t entry; 1718 1719 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1720 entry = pmd_to_swp_entry(orig_pmd); 1721 page = pfn_swap_entry_to_page(entry); 1722 flush_needed = 0; 1723 } else 1724 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1725 1726 if (PageAnon(page)) { 1727 zap_deposited_table(tlb->mm, pmd); 1728 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1729 } else { 1730 if (arch_needs_pgtable_deposit()) 1731 zap_deposited_table(tlb->mm, pmd); 1732 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1733 } 1734 1735 spin_unlock(ptl); 1736 if (flush_needed) 1737 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1738 } 1739 return 1; 1740 } 1741 1742 #ifndef pmd_move_must_withdraw 1743 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1744 spinlock_t *old_pmd_ptl, 1745 struct vm_area_struct *vma) 1746 { 1747 /* 1748 * With split pmd lock we also need to move preallocated 1749 * PTE page table if new_pmd is on different PMD page table. 1750 * 1751 * We also don't deposit and withdraw tables for file pages. 1752 */ 1753 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1754 } 1755 #endif 1756 1757 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1758 { 1759 #ifdef CONFIG_MEM_SOFT_DIRTY 1760 if (unlikely(is_pmd_migration_entry(pmd))) 1761 pmd = pmd_swp_mksoft_dirty(pmd); 1762 else if (pmd_present(pmd)) 1763 pmd = pmd_mksoft_dirty(pmd); 1764 #endif 1765 return pmd; 1766 } 1767 1768 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1769 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1770 { 1771 spinlock_t *old_ptl, *new_ptl; 1772 pmd_t pmd; 1773 struct mm_struct *mm = vma->vm_mm; 1774 bool force_flush = false; 1775 1776 /* 1777 * The destination pmd shouldn't be established, free_pgtables() 1778 * should have release it. 1779 */ 1780 if (WARN_ON(!pmd_none(*new_pmd))) { 1781 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1782 return false; 1783 } 1784 1785 /* 1786 * We don't have to worry about the ordering of src and dst 1787 * ptlocks because exclusive mmap_lock prevents deadlock. 1788 */ 1789 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1790 if (old_ptl) { 1791 new_ptl = pmd_lockptr(mm, new_pmd); 1792 if (new_ptl != old_ptl) 1793 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1794 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1795 if (pmd_present(pmd)) 1796 force_flush = true; 1797 VM_BUG_ON(!pmd_none(*new_pmd)); 1798 1799 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1800 pgtable_t pgtable; 1801 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1802 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1803 } 1804 pmd = move_soft_dirty_pmd(pmd); 1805 set_pmd_at(mm, new_addr, new_pmd, pmd); 1806 if (force_flush) 1807 flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1808 if (new_ptl != old_ptl) 1809 spin_unlock(new_ptl); 1810 spin_unlock(old_ptl); 1811 return true; 1812 } 1813 return false; 1814 } 1815 1816 /* 1817 * Returns 1818 * - 0 if PMD could not be locked 1819 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary 1820 * or if prot_numa but THP migration is not supported 1821 * - HPAGE_PMD_NR if protections changed and TLB flush necessary 1822 */ 1823 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1824 pmd_t *pmd, unsigned long addr, pgprot_t newprot, 1825 unsigned long cp_flags) 1826 { 1827 struct mm_struct *mm = vma->vm_mm; 1828 spinlock_t *ptl; 1829 pmd_t oldpmd, entry; 1830 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1831 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1832 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1833 int ret = 1; 1834 1835 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1836 1837 if (prot_numa && !thp_migration_supported()) 1838 return 1; 1839 1840 ptl = __pmd_trans_huge_lock(pmd, vma); 1841 if (!ptl) 1842 return 0; 1843 1844 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1845 if (is_swap_pmd(*pmd)) { 1846 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1847 struct page *page = pfn_swap_entry_to_page(entry); 1848 1849 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1850 if (is_writable_migration_entry(entry)) { 1851 pmd_t newpmd; 1852 /* 1853 * A protection check is difficult so 1854 * just be safe and disable write 1855 */ 1856 if (PageAnon(page)) 1857 entry = make_readable_exclusive_migration_entry(swp_offset(entry)); 1858 else 1859 entry = make_readable_migration_entry(swp_offset(entry)); 1860 newpmd = swp_entry_to_pmd(entry); 1861 if (pmd_swp_soft_dirty(*pmd)) 1862 newpmd = pmd_swp_mksoft_dirty(newpmd); 1863 if (pmd_swp_uffd_wp(*pmd)) 1864 newpmd = pmd_swp_mkuffd_wp(newpmd); 1865 set_pmd_at(mm, addr, pmd, newpmd); 1866 } 1867 goto unlock; 1868 } 1869 #endif 1870 1871 if (prot_numa) { 1872 struct page *page; 1873 bool toptier; 1874 /* 1875 * Avoid trapping faults against the zero page. The read-only 1876 * data is likely to be read-cached on the local CPU and 1877 * local/remote hits to the zero page are not interesting. 1878 */ 1879 if (is_huge_zero_pmd(*pmd)) 1880 goto unlock; 1881 1882 if (pmd_protnone(*pmd)) 1883 goto unlock; 1884 1885 page = pmd_page(*pmd); 1886 toptier = node_is_toptier(page_to_nid(page)); 1887 /* 1888 * Skip scanning top tier node if normal numa 1889 * balancing is disabled 1890 */ 1891 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 1892 toptier) 1893 goto unlock; 1894 1895 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING && 1896 !toptier) 1897 xchg_page_access_time(page, jiffies_to_msecs(jiffies)); 1898 } 1899 /* 1900 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 1901 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1902 * which is also under mmap_read_lock(mm): 1903 * 1904 * CPU0: CPU1: 1905 * change_huge_pmd(prot_numa=1) 1906 * pmdp_huge_get_and_clear_notify() 1907 * madvise_dontneed() 1908 * zap_pmd_range() 1909 * pmd_trans_huge(*pmd) == 0 (without ptl) 1910 * // skip the pmd 1911 * set_pmd_at(); 1912 * // pmd is re-established 1913 * 1914 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1915 * which may break userspace. 1916 * 1917 * pmdp_invalidate_ad() is required to make sure we don't miss 1918 * dirty/young flags set by hardware. 1919 */ 1920 oldpmd = pmdp_invalidate_ad(vma, addr, pmd); 1921 1922 entry = pmd_modify(oldpmd, newprot); 1923 if (uffd_wp) 1924 entry = pmd_mkuffd_wp(entry); 1925 else if (uffd_wp_resolve) 1926 /* 1927 * Leave the write bit to be handled by PF interrupt 1928 * handler, then things like COW could be properly 1929 * handled. 1930 */ 1931 entry = pmd_clear_uffd_wp(entry); 1932 1933 /* See change_pte_range(). */ 1934 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) && 1935 can_change_pmd_writable(vma, addr, entry)) 1936 entry = pmd_mkwrite(entry); 1937 1938 ret = HPAGE_PMD_NR; 1939 set_pmd_at(mm, addr, pmd, entry); 1940 1941 if (huge_pmd_needs_flush(oldpmd, entry)) 1942 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); 1943 unlock: 1944 spin_unlock(ptl); 1945 return ret; 1946 } 1947 1948 /* 1949 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1950 * 1951 * Note that if it returns page table lock pointer, this routine returns without 1952 * unlocking page table lock. So callers must unlock it. 1953 */ 1954 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1955 { 1956 spinlock_t *ptl; 1957 ptl = pmd_lock(vma->vm_mm, pmd); 1958 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 1959 pmd_devmap(*pmd))) 1960 return ptl; 1961 spin_unlock(ptl); 1962 return NULL; 1963 } 1964 1965 /* 1966 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. 1967 * 1968 * Note that if it returns page table lock pointer, this routine returns without 1969 * unlocking page table lock. So callers must unlock it. 1970 */ 1971 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 1972 { 1973 spinlock_t *ptl; 1974 1975 ptl = pud_lock(vma->vm_mm, pud); 1976 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 1977 return ptl; 1978 spin_unlock(ptl); 1979 return NULL; 1980 } 1981 1982 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1983 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 1984 pud_t *pud, unsigned long addr) 1985 { 1986 spinlock_t *ptl; 1987 1988 ptl = __pud_trans_huge_lock(pud, vma); 1989 if (!ptl) 1990 return 0; 1991 1992 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 1993 tlb_remove_pud_tlb_entry(tlb, pud, addr); 1994 if (vma_is_special_huge(vma)) { 1995 spin_unlock(ptl); 1996 /* No zero page support yet */ 1997 } else { 1998 /* No support for anonymous PUD pages yet */ 1999 BUG(); 2000 } 2001 return 1; 2002 } 2003 2004 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 2005 unsigned long haddr) 2006 { 2007 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 2008 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2009 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 2010 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 2011 2012 count_vm_event(THP_SPLIT_PUD); 2013 2014 pudp_huge_clear_flush_notify(vma, haddr, pud); 2015 } 2016 2017 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 2018 unsigned long address) 2019 { 2020 spinlock_t *ptl; 2021 struct mmu_notifier_range range; 2022 2023 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2024 address & HPAGE_PUD_MASK, 2025 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 2026 mmu_notifier_invalidate_range_start(&range); 2027 ptl = pud_lock(vma->vm_mm, pud); 2028 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 2029 goto out; 2030 __split_huge_pud_locked(vma, pud, range.start); 2031 2032 out: 2033 spin_unlock(ptl); 2034 /* 2035 * No need to double call mmu_notifier->invalidate_range() callback as 2036 * the above pudp_huge_clear_flush_notify() did already call it. 2037 */ 2038 mmu_notifier_invalidate_range_only_end(&range); 2039 } 2040 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 2041 2042 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2043 unsigned long haddr, pmd_t *pmd) 2044 { 2045 struct mm_struct *mm = vma->vm_mm; 2046 pgtable_t pgtable; 2047 pmd_t _pmd; 2048 int i; 2049 2050 /* 2051 * Leave pmd empty until pte is filled note that it is fine to delay 2052 * notification until mmu_notifier_invalidate_range_end() as we are 2053 * replacing a zero pmd write protected page with a zero pte write 2054 * protected page. 2055 * 2056 * See Documentation/mm/mmu_notifier.rst 2057 */ 2058 pmdp_huge_clear_flush(vma, haddr, pmd); 2059 2060 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2061 pmd_populate(mm, &_pmd, pgtable); 2062 2063 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 2064 pte_t *pte, entry; 2065 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 2066 entry = pte_mkspecial(entry); 2067 pte = pte_offset_map(&_pmd, haddr); 2068 VM_BUG_ON(!pte_none(*pte)); 2069 set_pte_at(mm, haddr, pte, entry); 2070 pte_unmap(pte); 2071 } 2072 smp_wmb(); /* make pte visible before pmd */ 2073 pmd_populate(mm, pmd, pgtable); 2074 } 2075 2076 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2077 unsigned long haddr, bool freeze) 2078 { 2079 struct mm_struct *mm = vma->vm_mm; 2080 struct page *page; 2081 pgtable_t pgtable; 2082 pmd_t old_pmd, _pmd; 2083 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 2084 bool anon_exclusive = false, dirty = false; 2085 unsigned long addr; 2086 int i; 2087 2088 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2089 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2090 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2091 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2092 && !pmd_devmap(*pmd)); 2093 2094 count_vm_event(THP_SPLIT_PMD); 2095 2096 if (!vma_is_anonymous(vma)) { 2097 old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 2098 /* 2099 * We are going to unmap this huge page. So 2100 * just go ahead and zap it 2101 */ 2102 if (arch_needs_pgtable_deposit()) 2103 zap_deposited_table(mm, pmd); 2104 if (vma_is_special_huge(vma)) 2105 return; 2106 if (unlikely(is_pmd_migration_entry(old_pmd))) { 2107 swp_entry_t entry; 2108 2109 entry = pmd_to_swp_entry(old_pmd); 2110 page = pfn_swap_entry_to_page(entry); 2111 } else { 2112 page = pmd_page(old_pmd); 2113 if (!PageDirty(page) && pmd_dirty(old_pmd)) 2114 set_page_dirty(page); 2115 if (!PageReferenced(page) && pmd_young(old_pmd)) 2116 SetPageReferenced(page); 2117 page_remove_rmap(page, vma, true); 2118 put_page(page); 2119 } 2120 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2121 return; 2122 } 2123 2124 if (is_huge_zero_pmd(*pmd)) { 2125 /* 2126 * FIXME: Do we want to invalidate secondary mmu by calling 2127 * mmu_notifier_invalidate_range() see comments below inside 2128 * __split_huge_pmd() ? 2129 * 2130 * We are going from a zero huge page write protected to zero 2131 * small page also write protected so it does not seems useful 2132 * to invalidate secondary mmu at this time. 2133 */ 2134 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2135 } 2136 2137 /* 2138 * Up to this point the pmd is present and huge and userland has the 2139 * whole access to the hugepage during the split (which happens in 2140 * place). If we overwrite the pmd with the not-huge version pointing 2141 * to the pte here (which of course we could if all CPUs were bug 2142 * free), userland could trigger a small page size TLB miss on the 2143 * small sized TLB while the hugepage TLB entry is still established in 2144 * the huge TLB. Some CPU doesn't like that. 2145 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2146 * 383 on page 105. Intel should be safe but is also warns that it's 2147 * only safe if the permission and cache attributes of the two entries 2148 * loaded in the two TLB is identical (which should be the case here). 2149 * But it is generally safer to never allow small and huge TLB entries 2150 * for the same virtual address to be loaded simultaneously. So instead 2151 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2152 * current pmd notpresent (atomically because here the pmd_trans_huge 2153 * must remain set at all times on the pmd until the split is complete 2154 * for this pmd), then we flush the SMP TLB and finally we write the 2155 * non-huge version of the pmd entry with pmd_populate. 2156 */ 2157 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2158 2159 pmd_migration = is_pmd_migration_entry(old_pmd); 2160 if (unlikely(pmd_migration)) { 2161 swp_entry_t entry; 2162 2163 entry = pmd_to_swp_entry(old_pmd); 2164 page = pfn_swap_entry_to_page(entry); 2165 write = is_writable_migration_entry(entry); 2166 if (PageAnon(page)) 2167 anon_exclusive = is_readable_exclusive_migration_entry(entry); 2168 young = is_migration_entry_young(entry); 2169 dirty = is_migration_entry_dirty(entry); 2170 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2171 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2172 } else { 2173 page = pmd_page(old_pmd); 2174 if (pmd_dirty(old_pmd)) { 2175 dirty = true; 2176 SetPageDirty(page); 2177 } 2178 write = pmd_write(old_pmd); 2179 young = pmd_young(old_pmd); 2180 soft_dirty = pmd_soft_dirty(old_pmd); 2181 uffd_wp = pmd_uffd_wp(old_pmd); 2182 2183 VM_BUG_ON_PAGE(!page_count(page), page); 2184 2185 /* 2186 * Without "freeze", we'll simply split the PMD, propagating the 2187 * PageAnonExclusive() flag for each PTE by setting it for 2188 * each subpage -- no need to (temporarily) clear. 2189 * 2190 * With "freeze" we want to replace mapped pages by 2191 * migration entries right away. This is only possible if we 2192 * managed to clear PageAnonExclusive() -- see 2193 * set_pmd_migration_entry(). 2194 * 2195 * In case we cannot clear PageAnonExclusive(), split the PMD 2196 * only and let try_to_migrate_one() fail later. 2197 * 2198 * See page_try_share_anon_rmap(): invalidate PMD first. 2199 */ 2200 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 2201 if (freeze && anon_exclusive && page_try_share_anon_rmap(page)) 2202 freeze = false; 2203 if (!freeze) 2204 page_ref_add(page, HPAGE_PMD_NR - 1); 2205 } 2206 2207 /* 2208 * Withdraw the table only after we mark the pmd entry invalid. 2209 * This's critical for some architectures (Power). 2210 */ 2211 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2212 pmd_populate(mm, &_pmd, pgtable); 2213 2214 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2215 pte_t entry, *pte; 2216 /* 2217 * Note that NUMA hinting access restrictions are not 2218 * transferred to avoid any possibility of altering 2219 * permissions across VMAs. 2220 */ 2221 if (freeze || pmd_migration) { 2222 swp_entry_t swp_entry; 2223 if (write) 2224 swp_entry = make_writable_migration_entry( 2225 page_to_pfn(page + i)); 2226 else if (anon_exclusive) 2227 swp_entry = make_readable_exclusive_migration_entry( 2228 page_to_pfn(page + i)); 2229 else 2230 swp_entry = make_readable_migration_entry( 2231 page_to_pfn(page + i)); 2232 if (young) 2233 swp_entry = make_migration_entry_young(swp_entry); 2234 if (dirty) 2235 swp_entry = make_migration_entry_dirty(swp_entry); 2236 entry = swp_entry_to_pte(swp_entry); 2237 if (soft_dirty) 2238 entry = pte_swp_mksoft_dirty(entry); 2239 if (uffd_wp) 2240 entry = pte_swp_mkuffd_wp(entry); 2241 } else { 2242 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2243 entry = maybe_mkwrite(entry, vma); 2244 if (anon_exclusive) 2245 SetPageAnonExclusive(page + i); 2246 if (!young) 2247 entry = pte_mkold(entry); 2248 /* NOTE: this may set soft-dirty too on some archs */ 2249 if (dirty) 2250 entry = pte_mkdirty(entry); 2251 /* 2252 * NOTE: this needs to happen after pte_mkdirty, 2253 * because some archs (sparc64, loongarch) could 2254 * set hw write bit when mkdirty. 2255 */ 2256 if (!write) 2257 entry = pte_wrprotect(entry); 2258 if (soft_dirty) 2259 entry = pte_mksoft_dirty(entry); 2260 if (uffd_wp) 2261 entry = pte_mkuffd_wp(entry); 2262 page_add_anon_rmap(page + i, vma, addr, false); 2263 } 2264 pte = pte_offset_map(&_pmd, addr); 2265 BUG_ON(!pte_none(*pte)); 2266 set_pte_at(mm, addr, pte, entry); 2267 pte_unmap(pte); 2268 } 2269 2270 if (!pmd_migration) 2271 page_remove_rmap(page, vma, true); 2272 if (freeze) 2273 put_page(page); 2274 2275 smp_wmb(); /* make pte visible before pmd */ 2276 pmd_populate(mm, pmd, pgtable); 2277 } 2278 2279 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2280 unsigned long address, bool freeze, struct folio *folio) 2281 { 2282 spinlock_t *ptl; 2283 struct mmu_notifier_range range; 2284 2285 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2286 address & HPAGE_PMD_MASK, 2287 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2288 mmu_notifier_invalidate_range_start(&range); 2289 ptl = pmd_lock(vma->vm_mm, pmd); 2290 2291 /* 2292 * If caller asks to setup a migration entry, we need a folio to check 2293 * pmd against. Otherwise we can end up replacing wrong folio. 2294 */ 2295 VM_BUG_ON(freeze && !folio); 2296 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); 2297 2298 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || 2299 is_pmd_migration_entry(*pmd)) { 2300 /* 2301 * It's safe to call pmd_page when folio is set because it's 2302 * guaranteed that pmd is present. 2303 */ 2304 if (folio && folio != page_folio(pmd_page(*pmd))) 2305 goto out; 2306 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2307 } 2308 2309 out: 2310 spin_unlock(ptl); 2311 /* 2312 * No need to double call mmu_notifier->invalidate_range() callback. 2313 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2314 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2315 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2316 * fault will trigger a flush_notify before pointing to a new page 2317 * (it is fine if the secondary mmu keeps pointing to the old zero 2318 * page in the meantime) 2319 * 3) Split a huge pmd into pte pointing to the same page. No need 2320 * to invalidate secondary tlb entry they are all still valid. 2321 * any further changes to individual pte will notify. So no need 2322 * to call mmu_notifier->invalidate_range() 2323 */ 2324 mmu_notifier_invalidate_range_only_end(&range); 2325 } 2326 2327 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2328 bool freeze, struct folio *folio) 2329 { 2330 pmd_t *pmd = mm_find_pmd(vma->vm_mm, address); 2331 2332 if (!pmd) 2333 return; 2334 2335 __split_huge_pmd(vma, pmd, address, freeze, folio); 2336 } 2337 2338 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) 2339 { 2340 /* 2341 * If the new address isn't hpage aligned and it could previously 2342 * contain an hugepage: check if we need to split an huge pmd. 2343 */ 2344 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && 2345 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), 2346 ALIGN(address, HPAGE_PMD_SIZE))) 2347 split_huge_pmd_address(vma, address, false, NULL); 2348 } 2349 2350 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2351 unsigned long start, 2352 unsigned long end, 2353 long adjust_next) 2354 { 2355 /* Check if we need to split start first. */ 2356 split_huge_pmd_if_needed(vma, start); 2357 2358 /* Check if we need to split end next. */ 2359 split_huge_pmd_if_needed(vma, end); 2360 2361 /* 2362 * If we're also updating the next vma vm_start, 2363 * check if we need to split it. 2364 */ 2365 if (adjust_next > 0) { 2366 struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end); 2367 unsigned long nstart = next->vm_start; 2368 nstart += adjust_next; 2369 split_huge_pmd_if_needed(next, nstart); 2370 } 2371 } 2372 2373 static void unmap_folio(struct folio *folio) 2374 { 2375 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | 2376 TTU_SYNC; 2377 2378 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 2379 2380 /* 2381 * Anon pages need migration entries to preserve them, but file 2382 * pages can simply be left unmapped, then faulted back on demand. 2383 * If that is ever changed (perhaps for mlock), update remap_page(). 2384 */ 2385 if (folio_test_anon(folio)) 2386 try_to_migrate(folio, ttu_flags); 2387 else 2388 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); 2389 } 2390 2391 static void remap_page(struct folio *folio, unsigned long nr) 2392 { 2393 int i = 0; 2394 2395 /* If unmap_folio() uses try_to_migrate() on file, remove this check */ 2396 if (!folio_test_anon(folio)) 2397 return; 2398 for (;;) { 2399 remove_migration_ptes(folio, folio, true); 2400 i += folio_nr_pages(folio); 2401 if (i >= nr) 2402 break; 2403 folio = folio_next(folio); 2404 } 2405 } 2406 2407 static void lru_add_page_tail(struct page *head, struct page *tail, 2408 struct lruvec *lruvec, struct list_head *list) 2409 { 2410 VM_BUG_ON_PAGE(!PageHead(head), head); 2411 VM_BUG_ON_PAGE(PageCompound(tail), head); 2412 VM_BUG_ON_PAGE(PageLRU(tail), head); 2413 lockdep_assert_held(&lruvec->lru_lock); 2414 2415 if (list) { 2416 /* page reclaim is reclaiming a huge page */ 2417 VM_WARN_ON(PageLRU(head)); 2418 get_page(tail); 2419 list_add_tail(&tail->lru, list); 2420 } else { 2421 /* head is still on lru (and we have it frozen) */ 2422 VM_WARN_ON(!PageLRU(head)); 2423 if (PageUnevictable(tail)) 2424 tail->mlock_count = 0; 2425 else 2426 list_add_tail(&tail->lru, &head->lru); 2427 SetPageLRU(tail); 2428 } 2429 } 2430 2431 static void __split_huge_page_tail(struct page *head, int tail, 2432 struct lruvec *lruvec, struct list_head *list) 2433 { 2434 struct page *page_tail = head + tail; 2435 2436 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2437 2438 /* 2439 * Clone page flags before unfreezing refcount. 2440 * 2441 * After successful get_page_unless_zero() might follow flags change, 2442 * for example lock_page() which set PG_waiters. 2443 * 2444 * Note that for mapped sub-pages of an anonymous THP, 2445 * PG_anon_exclusive has been cleared in unmap_folio() and is stored in 2446 * the migration entry instead from where remap_page() will restore it. 2447 * We can still have PG_anon_exclusive set on effectively unmapped and 2448 * unreferenced sub-pages of an anonymous THP: we can simply drop 2449 * PG_anon_exclusive (-> PG_mappedtodisk) for these here. 2450 */ 2451 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2452 page_tail->flags |= (head->flags & 2453 ((1L << PG_referenced) | 2454 (1L << PG_swapbacked) | 2455 (1L << PG_swapcache) | 2456 (1L << PG_mlocked) | 2457 (1L << PG_uptodate) | 2458 (1L << PG_active) | 2459 (1L << PG_workingset) | 2460 (1L << PG_locked) | 2461 (1L << PG_unevictable) | 2462 #ifdef CONFIG_ARCH_USES_PG_ARCH_X 2463 (1L << PG_arch_2) | 2464 (1L << PG_arch_3) | 2465 #endif 2466 (1L << PG_dirty) | 2467 LRU_GEN_MASK | LRU_REFS_MASK)); 2468 2469 /* ->mapping in first and second tail page is replaced by other uses */ 2470 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2471 page_tail); 2472 page_tail->mapping = head->mapping; 2473 page_tail->index = head->index + tail; 2474 2475 /* 2476 * page->private should not be set in tail pages with the exception 2477 * of swap cache pages that store the swp_entry_t in tail pages. 2478 * Fix up and warn once if private is unexpectedly set. 2479 * 2480 * What of 32-bit systems, on which head[1].compound_pincount overlays 2481 * head[1].private? No problem: THP_SWAP is not enabled on 32-bit, and 2482 * compound_pincount must be 0 for folio_ref_freeze() to have succeeded. 2483 */ 2484 if (!folio_test_swapcache(page_folio(head))) { 2485 VM_WARN_ON_ONCE_PAGE(page_tail->private != 0, page_tail); 2486 page_tail->private = 0; 2487 } 2488 2489 /* Page flags must be visible before we make the page non-compound. */ 2490 smp_wmb(); 2491 2492 /* 2493 * Clear PageTail before unfreezing page refcount. 2494 * 2495 * After successful get_page_unless_zero() might follow put_page() 2496 * which needs correct compound_head(). 2497 */ 2498 clear_compound_head(page_tail); 2499 2500 /* Finally unfreeze refcount. Additional reference from page cache. */ 2501 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2502 PageSwapCache(head))); 2503 2504 if (page_is_young(head)) 2505 set_page_young(page_tail); 2506 if (page_is_idle(head)) 2507 set_page_idle(page_tail); 2508 2509 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2510 2511 /* 2512 * always add to the tail because some iterators expect new 2513 * pages to show after the currently processed elements - e.g. 2514 * migrate_pages 2515 */ 2516 lru_add_page_tail(head, page_tail, lruvec, list); 2517 } 2518 2519 static void __split_huge_page(struct page *page, struct list_head *list, 2520 pgoff_t end) 2521 { 2522 struct folio *folio = page_folio(page); 2523 struct page *head = &folio->page; 2524 struct lruvec *lruvec; 2525 struct address_space *swap_cache = NULL; 2526 unsigned long offset = 0; 2527 unsigned int nr = thp_nr_pages(head); 2528 int i; 2529 2530 /* complete memcg works before add pages to LRU */ 2531 split_page_memcg(head, nr); 2532 2533 if (PageAnon(head) && PageSwapCache(head)) { 2534 swp_entry_t entry = { .val = page_private(head) }; 2535 2536 offset = swp_offset(entry); 2537 swap_cache = swap_address_space(entry); 2538 xa_lock(&swap_cache->i_pages); 2539 } 2540 2541 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ 2542 lruvec = folio_lruvec_lock(folio); 2543 2544 ClearPageHasHWPoisoned(head); 2545 2546 for (i = nr - 1; i >= 1; i--) { 2547 __split_huge_page_tail(head, i, lruvec, list); 2548 /* Some pages can be beyond EOF: drop them from page cache */ 2549 if (head[i].index >= end) { 2550 struct folio *tail = page_folio(head + i); 2551 2552 if (shmem_mapping(head->mapping)) 2553 shmem_uncharge(head->mapping->host, 1); 2554 else if (folio_test_clear_dirty(tail)) 2555 folio_account_cleaned(tail, 2556 inode_to_wb(folio->mapping->host)); 2557 __filemap_remove_folio(tail, NULL); 2558 folio_put(tail); 2559 } else if (!PageAnon(page)) { 2560 __xa_store(&head->mapping->i_pages, head[i].index, 2561 head + i, 0); 2562 } else if (swap_cache) { 2563 __xa_store(&swap_cache->i_pages, offset + i, 2564 head + i, 0); 2565 } 2566 } 2567 2568 ClearPageCompound(head); 2569 unlock_page_lruvec(lruvec); 2570 /* Caller disabled irqs, so they are still disabled here */ 2571 2572 split_page_owner(head, nr); 2573 2574 /* See comment in __split_huge_page_tail() */ 2575 if (PageAnon(head)) { 2576 /* Additional pin to swap cache */ 2577 if (PageSwapCache(head)) { 2578 page_ref_add(head, 2); 2579 xa_unlock(&swap_cache->i_pages); 2580 } else { 2581 page_ref_inc(head); 2582 } 2583 } else { 2584 /* Additional pin to page cache */ 2585 page_ref_add(head, 2); 2586 xa_unlock(&head->mapping->i_pages); 2587 } 2588 local_irq_enable(); 2589 2590 remap_page(folio, nr); 2591 2592 if (PageSwapCache(head)) { 2593 swp_entry_t entry = { .val = page_private(head) }; 2594 2595 split_swap_cluster(entry); 2596 } 2597 2598 for (i = 0; i < nr; i++) { 2599 struct page *subpage = head + i; 2600 if (subpage == page) 2601 continue; 2602 unlock_page(subpage); 2603 2604 /* 2605 * Subpages may be freed if there wasn't any mapping 2606 * like if add_to_swap() is running on a lru page that 2607 * had its mapping zapped. And freeing these pages 2608 * requires taking the lru_lock so we do the put_page 2609 * of the tail pages after the split is complete. 2610 */ 2611 free_page_and_swap_cache(subpage); 2612 } 2613 } 2614 2615 /* Racy check whether the huge page can be split */ 2616 bool can_split_folio(struct folio *folio, int *pextra_pins) 2617 { 2618 int extra_pins; 2619 2620 /* Additional pins from page cache */ 2621 if (folio_test_anon(folio)) 2622 extra_pins = folio_test_swapcache(folio) ? 2623 folio_nr_pages(folio) : 0; 2624 else 2625 extra_pins = folio_nr_pages(folio); 2626 if (pextra_pins) 2627 *pextra_pins = extra_pins; 2628 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1; 2629 } 2630 2631 /* 2632 * This function splits huge page into normal pages. @page can point to any 2633 * subpage of huge page to split. Split doesn't change the position of @page. 2634 * 2635 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2636 * The huge page must be locked. 2637 * 2638 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2639 * 2640 * Both head page and tail pages will inherit mapping, flags, and so on from 2641 * the hugepage. 2642 * 2643 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2644 * they are not mapped. 2645 * 2646 * Returns 0 if the hugepage is split successfully. 2647 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2648 * us. 2649 */ 2650 int split_huge_page_to_list(struct page *page, struct list_head *list) 2651 { 2652 struct folio *folio = page_folio(page); 2653 struct deferred_split *ds_queue = get_deferred_split_queue(&folio->page); 2654 XA_STATE(xas, &folio->mapping->i_pages, folio->index); 2655 struct anon_vma *anon_vma = NULL; 2656 struct address_space *mapping = NULL; 2657 int extra_pins, ret; 2658 pgoff_t end; 2659 bool is_hzp; 2660 2661 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); 2662 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 2663 2664 is_hzp = is_huge_zero_page(&folio->page); 2665 VM_WARN_ON_ONCE_FOLIO(is_hzp, folio); 2666 if (is_hzp) 2667 return -EBUSY; 2668 2669 if (folio_test_writeback(folio)) 2670 return -EBUSY; 2671 2672 if (folio_test_anon(folio)) { 2673 /* 2674 * The caller does not necessarily hold an mmap_lock that would 2675 * prevent the anon_vma disappearing so we first we take a 2676 * reference to it and then lock the anon_vma for write. This 2677 * is similar to folio_lock_anon_vma_read except the write lock 2678 * is taken to serialise against parallel split or collapse 2679 * operations. 2680 */ 2681 anon_vma = folio_get_anon_vma(folio); 2682 if (!anon_vma) { 2683 ret = -EBUSY; 2684 goto out; 2685 } 2686 end = -1; 2687 mapping = NULL; 2688 anon_vma_lock_write(anon_vma); 2689 } else { 2690 gfp_t gfp; 2691 2692 mapping = folio->mapping; 2693 2694 /* Truncated ? */ 2695 if (!mapping) { 2696 ret = -EBUSY; 2697 goto out; 2698 } 2699 2700 gfp = current_gfp_context(mapping_gfp_mask(mapping) & 2701 GFP_RECLAIM_MASK); 2702 2703 if (folio_test_private(folio) && 2704 !filemap_release_folio(folio, gfp)) { 2705 ret = -EBUSY; 2706 goto out; 2707 } 2708 2709 xas_split_alloc(&xas, folio, folio_order(folio), gfp); 2710 if (xas_error(&xas)) { 2711 ret = xas_error(&xas); 2712 goto out; 2713 } 2714 2715 anon_vma = NULL; 2716 i_mmap_lock_read(mapping); 2717 2718 /* 2719 *__split_huge_page() may need to trim off pages beyond EOF: 2720 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2721 * which cannot be nested inside the page tree lock. So note 2722 * end now: i_size itself may be changed at any moment, but 2723 * folio lock is good enough to serialize the trimming. 2724 */ 2725 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2726 if (shmem_mapping(mapping)) 2727 end = shmem_fallocend(mapping->host, end); 2728 } 2729 2730 /* 2731 * Racy check if we can split the page, before unmap_folio() will 2732 * split PMDs 2733 */ 2734 if (!can_split_folio(folio, &extra_pins)) { 2735 ret = -EAGAIN; 2736 goto out_unlock; 2737 } 2738 2739 unmap_folio(folio); 2740 2741 /* block interrupt reentry in xa_lock and spinlock */ 2742 local_irq_disable(); 2743 if (mapping) { 2744 /* 2745 * Check if the folio is present in page cache. 2746 * We assume all tail are present too, if folio is there. 2747 */ 2748 xas_lock(&xas); 2749 xas_reset(&xas); 2750 if (xas_load(&xas) != folio) 2751 goto fail; 2752 } 2753 2754 /* Prevent deferred_split_scan() touching ->_refcount */ 2755 spin_lock(&ds_queue->split_queue_lock); 2756 if (folio_ref_freeze(folio, 1 + extra_pins)) { 2757 if (!list_empty(page_deferred_list(&folio->page))) { 2758 ds_queue->split_queue_len--; 2759 list_del(page_deferred_list(&folio->page)); 2760 } 2761 spin_unlock(&ds_queue->split_queue_lock); 2762 if (mapping) { 2763 int nr = folio_nr_pages(folio); 2764 2765 xas_split(&xas, folio, folio_order(folio)); 2766 if (folio_test_swapbacked(folio)) { 2767 __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, 2768 -nr); 2769 } else { 2770 __lruvec_stat_mod_folio(folio, NR_FILE_THPS, 2771 -nr); 2772 filemap_nr_thps_dec(mapping); 2773 } 2774 } 2775 2776 __split_huge_page(page, list, end); 2777 ret = 0; 2778 } else { 2779 spin_unlock(&ds_queue->split_queue_lock); 2780 fail: 2781 if (mapping) 2782 xas_unlock(&xas); 2783 local_irq_enable(); 2784 remap_page(folio, folio_nr_pages(folio)); 2785 ret = -EAGAIN; 2786 } 2787 2788 out_unlock: 2789 if (anon_vma) { 2790 anon_vma_unlock_write(anon_vma); 2791 put_anon_vma(anon_vma); 2792 } 2793 if (mapping) 2794 i_mmap_unlock_read(mapping); 2795 out: 2796 xas_destroy(&xas); 2797 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2798 return ret; 2799 } 2800 2801 void free_transhuge_page(struct page *page) 2802 { 2803 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2804 unsigned long flags; 2805 2806 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2807 if (!list_empty(page_deferred_list(page))) { 2808 ds_queue->split_queue_len--; 2809 list_del(page_deferred_list(page)); 2810 } 2811 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2812 free_compound_page(page); 2813 } 2814 2815 void deferred_split_huge_page(struct page *page) 2816 { 2817 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2818 #ifdef CONFIG_MEMCG 2819 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 2820 #endif 2821 unsigned long flags; 2822 2823 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2824 2825 /* 2826 * The try_to_unmap() in page reclaim path might reach here too, 2827 * this may cause a race condition to corrupt deferred split queue. 2828 * And, if page reclaim is already handling the same page, it is 2829 * unnecessary to handle it again in shrinker. 2830 * 2831 * Check PageSwapCache to determine if the page is being 2832 * handled by page reclaim since THP swap would add the page into 2833 * swap cache before calling try_to_unmap(). 2834 */ 2835 if (PageSwapCache(page)) 2836 return; 2837 2838 if (!list_empty(page_deferred_list(page))) 2839 return; 2840 2841 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2842 if (list_empty(page_deferred_list(page))) { 2843 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2844 list_add_tail(page_deferred_list(page), &ds_queue->split_queue); 2845 ds_queue->split_queue_len++; 2846 #ifdef CONFIG_MEMCG 2847 if (memcg) 2848 set_shrinker_bit(memcg, page_to_nid(page), 2849 deferred_split_shrinker.id); 2850 #endif 2851 } 2852 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2853 } 2854 2855 static unsigned long deferred_split_count(struct shrinker *shrink, 2856 struct shrink_control *sc) 2857 { 2858 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2859 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2860 2861 #ifdef CONFIG_MEMCG 2862 if (sc->memcg) 2863 ds_queue = &sc->memcg->deferred_split_queue; 2864 #endif 2865 return READ_ONCE(ds_queue->split_queue_len); 2866 } 2867 2868 static unsigned long deferred_split_scan(struct shrinker *shrink, 2869 struct shrink_control *sc) 2870 { 2871 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2872 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2873 unsigned long flags; 2874 LIST_HEAD(list), *pos, *next; 2875 struct page *page; 2876 int split = 0; 2877 2878 #ifdef CONFIG_MEMCG 2879 if (sc->memcg) 2880 ds_queue = &sc->memcg->deferred_split_queue; 2881 #endif 2882 2883 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2884 /* Take pin on all head pages to avoid freeing them under us */ 2885 list_for_each_safe(pos, next, &ds_queue->split_queue) { 2886 page = list_entry((void *)pos, struct page, deferred_list); 2887 page = compound_head(page); 2888 if (get_page_unless_zero(page)) { 2889 list_move(page_deferred_list(page), &list); 2890 } else { 2891 /* We lost race with put_compound_page() */ 2892 list_del_init(page_deferred_list(page)); 2893 ds_queue->split_queue_len--; 2894 } 2895 if (!--sc->nr_to_scan) 2896 break; 2897 } 2898 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2899 2900 list_for_each_safe(pos, next, &list) { 2901 page = list_entry((void *)pos, struct page, deferred_list); 2902 if (!trylock_page(page)) 2903 goto next; 2904 /* split_huge_page() removes page from list on success */ 2905 if (!split_huge_page(page)) 2906 split++; 2907 unlock_page(page); 2908 next: 2909 put_page(page); 2910 } 2911 2912 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2913 list_splice_tail(&list, &ds_queue->split_queue); 2914 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2915 2916 /* 2917 * Stop shrinker if we didn't split any page, but the queue is empty. 2918 * This can happen if pages were freed under us. 2919 */ 2920 if (!split && list_empty(&ds_queue->split_queue)) 2921 return SHRINK_STOP; 2922 return split; 2923 } 2924 2925 static struct shrinker deferred_split_shrinker = { 2926 .count_objects = deferred_split_count, 2927 .scan_objects = deferred_split_scan, 2928 .seeks = DEFAULT_SEEKS, 2929 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | 2930 SHRINKER_NONSLAB, 2931 }; 2932 2933 #ifdef CONFIG_DEBUG_FS 2934 static void split_huge_pages_all(void) 2935 { 2936 struct zone *zone; 2937 struct page *page; 2938 struct folio *folio; 2939 unsigned long pfn, max_zone_pfn; 2940 unsigned long total = 0, split = 0; 2941 2942 pr_debug("Split all THPs\n"); 2943 for_each_zone(zone) { 2944 if (!managed_zone(zone)) 2945 continue; 2946 max_zone_pfn = zone_end_pfn(zone); 2947 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2948 int nr_pages; 2949 2950 page = pfn_to_online_page(pfn); 2951 if (!page || PageTail(page)) 2952 continue; 2953 folio = page_folio(page); 2954 if (!folio_try_get(folio)) 2955 continue; 2956 2957 if (unlikely(page_folio(page) != folio)) 2958 goto next; 2959 2960 if (zone != folio_zone(folio)) 2961 goto next; 2962 2963 if (!folio_test_large(folio) 2964 || folio_test_hugetlb(folio) 2965 || !folio_test_lru(folio)) 2966 goto next; 2967 2968 total++; 2969 folio_lock(folio); 2970 nr_pages = folio_nr_pages(folio); 2971 if (!split_folio(folio)) 2972 split++; 2973 pfn += nr_pages - 1; 2974 folio_unlock(folio); 2975 next: 2976 folio_put(folio); 2977 cond_resched(); 2978 } 2979 } 2980 2981 pr_debug("%lu of %lu THP split\n", split, total); 2982 } 2983 2984 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) 2985 { 2986 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || 2987 is_vm_hugetlb_page(vma); 2988 } 2989 2990 static int split_huge_pages_pid(int pid, unsigned long vaddr_start, 2991 unsigned long vaddr_end) 2992 { 2993 int ret = 0; 2994 struct task_struct *task; 2995 struct mm_struct *mm; 2996 unsigned long total = 0, split = 0; 2997 unsigned long addr; 2998 2999 vaddr_start &= PAGE_MASK; 3000 vaddr_end &= PAGE_MASK; 3001 3002 /* Find the task_struct from pid */ 3003 rcu_read_lock(); 3004 task = find_task_by_vpid(pid); 3005 if (!task) { 3006 rcu_read_unlock(); 3007 ret = -ESRCH; 3008 goto out; 3009 } 3010 get_task_struct(task); 3011 rcu_read_unlock(); 3012 3013 /* Find the mm_struct */ 3014 mm = get_task_mm(task); 3015 put_task_struct(task); 3016 3017 if (!mm) { 3018 ret = -EINVAL; 3019 goto out; 3020 } 3021 3022 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n", 3023 pid, vaddr_start, vaddr_end); 3024 3025 mmap_read_lock(mm); 3026 /* 3027 * always increase addr by PAGE_SIZE, since we could have a PTE page 3028 * table filled with PTE-mapped THPs, each of which is distinct. 3029 */ 3030 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { 3031 struct vm_area_struct *vma = vma_lookup(mm, addr); 3032 struct page *page; 3033 3034 if (!vma) 3035 break; 3036 3037 /* skip special VMA and hugetlb VMA */ 3038 if (vma_not_suitable_for_thp_split(vma)) { 3039 addr = vma->vm_end; 3040 continue; 3041 } 3042 3043 /* FOLL_DUMP to ignore special (like zero) pages */ 3044 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); 3045 3046 if (IS_ERR_OR_NULL(page)) 3047 continue; 3048 3049 if (!is_transparent_hugepage(page)) 3050 goto next; 3051 3052 total++; 3053 if (!can_split_folio(page_folio(page), NULL)) 3054 goto next; 3055 3056 if (!trylock_page(page)) 3057 goto next; 3058 3059 if (!split_huge_page(page)) 3060 split++; 3061 3062 unlock_page(page); 3063 next: 3064 put_page(page); 3065 cond_resched(); 3066 } 3067 mmap_read_unlock(mm); 3068 mmput(mm); 3069 3070 pr_debug("%lu of %lu THP split\n", split, total); 3071 3072 out: 3073 return ret; 3074 } 3075 3076 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, 3077 pgoff_t off_end) 3078 { 3079 struct filename *file; 3080 struct file *candidate; 3081 struct address_space *mapping; 3082 int ret = -EINVAL; 3083 pgoff_t index; 3084 int nr_pages = 1; 3085 unsigned long total = 0, split = 0; 3086 3087 file = getname_kernel(file_path); 3088 if (IS_ERR(file)) 3089 return ret; 3090 3091 candidate = file_open_name(file, O_RDONLY, 0); 3092 if (IS_ERR(candidate)) 3093 goto out; 3094 3095 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", 3096 file_path, off_start, off_end); 3097 3098 mapping = candidate->f_mapping; 3099 3100 for (index = off_start; index < off_end; index += nr_pages) { 3101 struct folio *folio = __filemap_get_folio(mapping, index, 3102 FGP_ENTRY, 0); 3103 3104 nr_pages = 1; 3105 if (xa_is_value(folio) || !folio) 3106 continue; 3107 3108 if (!folio_test_large(folio)) 3109 goto next; 3110 3111 total++; 3112 nr_pages = folio_nr_pages(folio); 3113 3114 if (!folio_trylock(folio)) 3115 goto next; 3116 3117 if (!split_folio(folio)) 3118 split++; 3119 3120 folio_unlock(folio); 3121 next: 3122 folio_put(folio); 3123 cond_resched(); 3124 } 3125 3126 filp_close(candidate, NULL); 3127 ret = 0; 3128 3129 pr_debug("%lu of %lu file-backed THP split\n", split, total); 3130 out: 3131 putname(file); 3132 return ret; 3133 } 3134 3135 #define MAX_INPUT_BUF_SZ 255 3136 3137 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, 3138 size_t count, loff_t *ppops) 3139 { 3140 static DEFINE_MUTEX(split_debug_mutex); 3141 ssize_t ret; 3142 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */ 3143 char input_buf[MAX_INPUT_BUF_SZ]; 3144 int pid; 3145 unsigned long vaddr_start, vaddr_end; 3146 3147 ret = mutex_lock_interruptible(&split_debug_mutex); 3148 if (ret) 3149 return ret; 3150 3151 ret = -EFAULT; 3152 3153 memset(input_buf, 0, MAX_INPUT_BUF_SZ); 3154 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) 3155 goto out; 3156 3157 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; 3158 3159 if (input_buf[0] == '/') { 3160 char *tok; 3161 char *buf = input_buf; 3162 char file_path[MAX_INPUT_BUF_SZ]; 3163 pgoff_t off_start = 0, off_end = 0; 3164 size_t input_len = strlen(input_buf); 3165 3166 tok = strsep(&buf, ","); 3167 if (tok) { 3168 strcpy(file_path, tok); 3169 } else { 3170 ret = -EINVAL; 3171 goto out; 3172 } 3173 3174 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end); 3175 if (ret != 2) { 3176 ret = -EINVAL; 3177 goto out; 3178 } 3179 ret = split_huge_pages_in_file(file_path, off_start, off_end); 3180 if (!ret) 3181 ret = input_len; 3182 3183 goto out; 3184 } 3185 3186 ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end); 3187 if (ret == 1 && pid == 1) { 3188 split_huge_pages_all(); 3189 ret = strlen(input_buf); 3190 goto out; 3191 } else if (ret != 3) { 3192 ret = -EINVAL; 3193 goto out; 3194 } 3195 3196 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end); 3197 if (!ret) 3198 ret = strlen(input_buf); 3199 out: 3200 mutex_unlock(&split_debug_mutex); 3201 return ret; 3202 3203 } 3204 3205 static const struct file_operations split_huge_pages_fops = { 3206 .owner = THIS_MODULE, 3207 .write = split_huge_pages_write, 3208 .llseek = no_llseek, 3209 }; 3210 3211 static int __init split_huge_pages_debugfs(void) 3212 { 3213 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 3214 &split_huge_pages_fops); 3215 return 0; 3216 } 3217 late_initcall(split_huge_pages_debugfs); 3218 #endif 3219 3220 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 3221 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 3222 struct page *page) 3223 { 3224 struct vm_area_struct *vma = pvmw->vma; 3225 struct mm_struct *mm = vma->vm_mm; 3226 unsigned long address = pvmw->address; 3227 bool anon_exclusive; 3228 pmd_t pmdval; 3229 swp_entry_t entry; 3230 pmd_t pmdswp; 3231 3232 if (!(pvmw->pmd && !pvmw->pte)) 3233 return 0; 3234 3235 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 3236 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 3237 3238 /* See page_try_share_anon_rmap(): invalidate PMD first. */ 3239 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 3240 if (anon_exclusive && page_try_share_anon_rmap(page)) { 3241 set_pmd_at(mm, address, pvmw->pmd, pmdval); 3242 return -EBUSY; 3243 } 3244 3245 if (pmd_dirty(pmdval)) 3246 set_page_dirty(page); 3247 if (pmd_write(pmdval)) 3248 entry = make_writable_migration_entry(page_to_pfn(page)); 3249 else if (anon_exclusive) 3250 entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); 3251 else 3252 entry = make_readable_migration_entry(page_to_pfn(page)); 3253 if (pmd_young(pmdval)) 3254 entry = make_migration_entry_young(entry); 3255 if (pmd_dirty(pmdval)) 3256 entry = make_migration_entry_dirty(entry); 3257 pmdswp = swp_entry_to_pmd(entry); 3258 if (pmd_soft_dirty(pmdval)) 3259 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3260 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3261 page_remove_rmap(page, vma, true); 3262 put_page(page); 3263 trace_set_migration_pmd(address, pmd_val(pmdswp)); 3264 3265 return 0; 3266 } 3267 3268 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3269 { 3270 struct vm_area_struct *vma = pvmw->vma; 3271 struct mm_struct *mm = vma->vm_mm; 3272 unsigned long address = pvmw->address; 3273 unsigned long haddr = address & HPAGE_PMD_MASK; 3274 pmd_t pmde; 3275 swp_entry_t entry; 3276 3277 if (!(pvmw->pmd && !pvmw->pte)) 3278 return; 3279 3280 entry = pmd_to_swp_entry(*pvmw->pmd); 3281 get_page(new); 3282 pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot)); 3283 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3284 pmde = pmd_mksoft_dirty(pmde); 3285 if (is_writable_migration_entry(entry)) 3286 pmde = maybe_pmd_mkwrite(pmde, vma); 3287 if (pmd_swp_uffd_wp(*pvmw->pmd)) 3288 pmde = pmd_mkuffd_wp(pmde); 3289 if (!is_migration_entry_young(entry)) 3290 pmde = pmd_mkold(pmde); 3291 /* NOTE: this may contain setting soft-dirty on some archs */ 3292 if (PageDirty(new) && is_migration_entry_dirty(entry)) 3293 pmde = pmd_mkdirty(pmde); 3294 3295 if (PageAnon(new)) { 3296 rmap_t rmap_flags = RMAP_COMPOUND; 3297 3298 if (!is_readable_migration_entry(entry)) 3299 rmap_flags |= RMAP_EXCLUSIVE; 3300 3301 page_add_anon_rmap(new, vma, haddr, rmap_flags); 3302 } else { 3303 page_add_file_rmap(new, vma, true); 3304 } 3305 VM_BUG_ON(pmd_write(pmde) && PageAnon(new) && !PageAnonExclusive(new)); 3306 set_pmd_at(mm, haddr, pvmw->pmd, pmde); 3307 3308 /* No need to invalidate - it was non-present before */ 3309 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3310 trace_remove_migration_pmd(address, pmd_val(pmde)); 3311 } 3312 #endif 3313