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 1039 assert_spin_locked(pmd_lockptr(mm, pmd)); 1040 1041 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1042 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1043 (FOLL_PIN | FOLL_GET))) 1044 return NULL; 1045 1046 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 1047 return NULL; 1048 1049 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 1050 /* pass */; 1051 else 1052 return NULL; 1053 1054 if (flags & FOLL_TOUCH) 1055 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1056 1057 /* 1058 * device mapped pages can only be returned if the 1059 * caller will manage the page reference count. 1060 */ 1061 if (!(flags & (FOLL_GET | FOLL_PIN))) 1062 return ERR_PTR(-EEXIST); 1063 1064 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 1065 *pgmap = get_dev_pagemap(pfn, *pgmap); 1066 if (!*pgmap) 1067 return ERR_PTR(-EFAULT); 1068 page = pfn_to_page(pfn); 1069 if (!try_grab_page(page, flags)) 1070 page = ERR_PTR(-ENOMEM); 1071 1072 return page; 1073 } 1074 1075 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1076 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1077 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) 1078 { 1079 spinlock_t *dst_ptl, *src_ptl; 1080 struct page *src_page; 1081 pmd_t pmd; 1082 pgtable_t pgtable = NULL; 1083 int ret = -ENOMEM; 1084 1085 /* Skip if can be re-fill on fault */ 1086 if (!vma_is_anonymous(dst_vma)) 1087 return 0; 1088 1089 pgtable = pte_alloc_one(dst_mm); 1090 if (unlikely(!pgtable)) 1091 goto out; 1092 1093 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1094 src_ptl = pmd_lockptr(src_mm, src_pmd); 1095 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1096 1097 ret = -EAGAIN; 1098 pmd = *src_pmd; 1099 1100 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1101 if (unlikely(is_swap_pmd(pmd))) { 1102 swp_entry_t entry = pmd_to_swp_entry(pmd); 1103 1104 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1105 if (!is_readable_migration_entry(entry)) { 1106 entry = make_readable_migration_entry( 1107 swp_offset(entry)); 1108 pmd = swp_entry_to_pmd(entry); 1109 if (pmd_swp_soft_dirty(*src_pmd)) 1110 pmd = pmd_swp_mksoft_dirty(pmd); 1111 if (pmd_swp_uffd_wp(*src_pmd)) 1112 pmd = pmd_swp_mkuffd_wp(pmd); 1113 set_pmd_at(src_mm, addr, src_pmd, pmd); 1114 } 1115 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1116 mm_inc_nr_ptes(dst_mm); 1117 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1118 if (!userfaultfd_wp(dst_vma)) 1119 pmd = pmd_swp_clear_uffd_wp(pmd); 1120 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1121 ret = 0; 1122 goto out_unlock; 1123 } 1124 #endif 1125 1126 if (unlikely(!pmd_trans_huge(pmd))) { 1127 pte_free(dst_mm, pgtable); 1128 goto out_unlock; 1129 } 1130 /* 1131 * When page table lock is held, the huge zero pmd should not be 1132 * under splitting since we don't split the page itself, only pmd to 1133 * a page table. 1134 */ 1135 if (is_huge_zero_pmd(pmd)) { 1136 /* 1137 * get_huge_zero_page() will never allocate a new page here, 1138 * since we already have a zero page to copy. It just takes a 1139 * reference. 1140 */ 1141 mm_get_huge_zero_page(dst_mm); 1142 goto out_zero_page; 1143 } 1144 1145 src_page = pmd_page(pmd); 1146 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1147 1148 get_page(src_page); 1149 if (unlikely(page_try_dup_anon_rmap(src_page, true, src_vma))) { 1150 /* Page maybe pinned: split and retry the fault on PTEs. */ 1151 put_page(src_page); 1152 pte_free(dst_mm, pgtable); 1153 spin_unlock(src_ptl); 1154 spin_unlock(dst_ptl); 1155 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); 1156 return -EAGAIN; 1157 } 1158 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1159 out_zero_page: 1160 mm_inc_nr_ptes(dst_mm); 1161 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1162 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1163 if (!userfaultfd_wp(dst_vma)) 1164 pmd = pmd_clear_uffd_wp(pmd); 1165 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1166 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1167 1168 ret = 0; 1169 out_unlock: 1170 spin_unlock(src_ptl); 1171 spin_unlock(dst_ptl); 1172 out: 1173 return ret; 1174 } 1175 1176 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1177 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1178 pud_t *pud, bool write) 1179 { 1180 pud_t _pud; 1181 1182 _pud = pud_mkyoung(*pud); 1183 if (write) 1184 _pud = pud_mkdirty(_pud); 1185 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1186 pud, _pud, write)) 1187 update_mmu_cache_pud(vma, addr, pud); 1188 } 1189 1190 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1191 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1192 { 1193 unsigned long pfn = pud_pfn(*pud); 1194 struct mm_struct *mm = vma->vm_mm; 1195 struct page *page; 1196 1197 assert_spin_locked(pud_lockptr(mm, pud)); 1198 1199 if (flags & FOLL_WRITE && !pud_write(*pud)) 1200 return NULL; 1201 1202 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1203 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1204 (FOLL_PIN | FOLL_GET))) 1205 return NULL; 1206 1207 if (pud_present(*pud) && pud_devmap(*pud)) 1208 /* pass */; 1209 else 1210 return NULL; 1211 1212 if (flags & FOLL_TOUCH) 1213 touch_pud(vma, addr, pud, flags & FOLL_WRITE); 1214 1215 /* 1216 * device mapped pages can only be returned if the 1217 * caller will manage the page reference count. 1218 * 1219 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here: 1220 */ 1221 if (!(flags & (FOLL_GET | FOLL_PIN))) 1222 return ERR_PTR(-EEXIST); 1223 1224 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1225 *pgmap = get_dev_pagemap(pfn, *pgmap); 1226 if (!*pgmap) 1227 return ERR_PTR(-EFAULT); 1228 page = pfn_to_page(pfn); 1229 if (!try_grab_page(page, flags)) 1230 page = ERR_PTR(-ENOMEM); 1231 1232 return page; 1233 } 1234 1235 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1236 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1237 struct vm_area_struct *vma) 1238 { 1239 spinlock_t *dst_ptl, *src_ptl; 1240 pud_t pud; 1241 int ret; 1242 1243 dst_ptl = pud_lock(dst_mm, dst_pud); 1244 src_ptl = pud_lockptr(src_mm, src_pud); 1245 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1246 1247 ret = -EAGAIN; 1248 pud = *src_pud; 1249 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1250 goto out_unlock; 1251 1252 /* 1253 * When page table lock is held, the huge zero pud should not be 1254 * under splitting since we don't split the page itself, only pud to 1255 * a page table. 1256 */ 1257 if (is_huge_zero_pud(pud)) { 1258 /* No huge zero pud yet */ 1259 } 1260 1261 /* 1262 * TODO: once we support anonymous pages, use page_try_dup_anon_rmap() 1263 * and split if duplicating fails. 1264 */ 1265 pudp_set_wrprotect(src_mm, addr, src_pud); 1266 pud = pud_mkold(pud_wrprotect(pud)); 1267 set_pud_at(dst_mm, addr, dst_pud, pud); 1268 1269 ret = 0; 1270 out_unlock: 1271 spin_unlock(src_ptl); 1272 spin_unlock(dst_ptl); 1273 return ret; 1274 } 1275 1276 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1277 { 1278 bool write = vmf->flags & FAULT_FLAG_WRITE; 1279 1280 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1281 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1282 goto unlock; 1283 1284 touch_pud(vmf->vma, vmf->address, vmf->pud, write); 1285 unlock: 1286 spin_unlock(vmf->ptl); 1287 } 1288 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1289 1290 void huge_pmd_set_accessed(struct vm_fault *vmf) 1291 { 1292 bool write = vmf->flags & FAULT_FLAG_WRITE; 1293 1294 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1295 if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) 1296 goto unlock; 1297 1298 touch_pmd(vmf->vma, vmf->address, vmf->pmd, write); 1299 1300 unlock: 1301 spin_unlock(vmf->ptl); 1302 } 1303 1304 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) 1305 { 1306 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; 1307 struct vm_area_struct *vma = vmf->vma; 1308 struct folio *folio; 1309 struct page *page; 1310 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1311 pmd_t orig_pmd = vmf->orig_pmd; 1312 1313 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1314 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1315 1316 VM_BUG_ON(unshare && (vmf->flags & FAULT_FLAG_WRITE)); 1317 VM_BUG_ON(!unshare && !(vmf->flags & FAULT_FLAG_WRITE)); 1318 1319 if (is_huge_zero_pmd(orig_pmd)) 1320 goto fallback; 1321 1322 spin_lock(vmf->ptl); 1323 1324 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1325 spin_unlock(vmf->ptl); 1326 return 0; 1327 } 1328 1329 page = pmd_page(orig_pmd); 1330 folio = page_folio(page); 1331 VM_BUG_ON_PAGE(!PageHead(page), page); 1332 1333 /* Early check when only holding the PT lock. */ 1334 if (PageAnonExclusive(page)) 1335 goto reuse; 1336 1337 if (!folio_trylock(folio)) { 1338 folio_get(folio); 1339 spin_unlock(vmf->ptl); 1340 folio_lock(folio); 1341 spin_lock(vmf->ptl); 1342 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1343 spin_unlock(vmf->ptl); 1344 folio_unlock(folio); 1345 folio_put(folio); 1346 return 0; 1347 } 1348 folio_put(folio); 1349 } 1350 1351 /* Recheck after temporarily dropping the PT lock. */ 1352 if (PageAnonExclusive(page)) { 1353 folio_unlock(folio); 1354 goto reuse; 1355 } 1356 1357 /* 1358 * See do_wp_page(): we can only reuse the folio exclusively if 1359 * there are no additional references. Note that we always drain 1360 * the LRU pagevecs immediately after adding a THP. 1361 */ 1362 if (folio_ref_count(folio) > 1363 1 + folio_test_swapcache(folio) * folio_nr_pages(folio)) 1364 goto unlock_fallback; 1365 if (folio_test_swapcache(folio)) 1366 folio_free_swap(folio); 1367 if (folio_ref_count(folio) == 1) { 1368 pmd_t entry; 1369 1370 page_move_anon_rmap(page, vma); 1371 folio_unlock(folio); 1372 reuse: 1373 if (unlikely(unshare)) { 1374 spin_unlock(vmf->ptl); 1375 return 0; 1376 } 1377 entry = pmd_mkyoung(orig_pmd); 1378 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1379 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1380 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1381 spin_unlock(vmf->ptl); 1382 return VM_FAULT_WRITE; 1383 } 1384 1385 unlock_fallback: 1386 folio_unlock(folio); 1387 spin_unlock(vmf->ptl); 1388 fallback: 1389 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1390 return VM_FAULT_FALLBACK; 1391 } 1392 1393 /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */ 1394 static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page, 1395 struct vm_area_struct *vma, 1396 unsigned int flags) 1397 { 1398 /* If the pmd is writable, we can write to the page. */ 1399 if (pmd_write(pmd)) 1400 return true; 1401 1402 /* Maybe FOLL_FORCE is set to override it? */ 1403 if (!(flags & FOLL_FORCE)) 1404 return false; 1405 1406 /* But FOLL_FORCE has no effect on shared mappings */ 1407 if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED)) 1408 return false; 1409 1410 /* ... or read-only private ones */ 1411 if (!(vma->vm_flags & VM_MAYWRITE)) 1412 return false; 1413 1414 /* ... or already writable ones that just need to take a write fault */ 1415 if (vma->vm_flags & VM_WRITE) 1416 return false; 1417 1418 /* 1419 * See can_change_pte_writable(): we broke COW and could map the page 1420 * writable if we have an exclusive anonymous page ... 1421 */ 1422 if (!page || !PageAnon(page) || !PageAnonExclusive(page)) 1423 return false; 1424 1425 /* ... and a write-fault isn't required for other reasons. */ 1426 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) 1427 return false; 1428 return !userfaultfd_huge_pmd_wp(vma, pmd); 1429 } 1430 1431 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1432 unsigned long addr, 1433 pmd_t *pmd, 1434 unsigned int flags) 1435 { 1436 struct mm_struct *mm = vma->vm_mm; 1437 struct page *page; 1438 1439 assert_spin_locked(pmd_lockptr(mm, pmd)); 1440 1441 page = pmd_page(*pmd); 1442 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1443 1444 if ((flags & FOLL_WRITE) && 1445 !can_follow_write_pmd(*pmd, page, vma, flags)) 1446 return NULL; 1447 1448 /* Avoid dumping huge zero page */ 1449 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1450 return ERR_PTR(-EFAULT); 1451 1452 /* Full NUMA hinting faults to serialise migration in fault paths */ 1453 if (pmd_protnone(*pmd) && !gup_can_follow_protnone(flags)) 1454 return NULL; 1455 1456 if (!pmd_write(*pmd) && gup_must_unshare(flags, page)) 1457 return ERR_PTR(-EMLINK); 1458 1459 VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) && 1460 !PageAnonExclusive(page), page); 1461 1462 if (!try_grab_page(page, flags)) 1463 return ERR_PTR(-ENOMEM); 1464 1465 if (flags & FOLL_TOUCH) 1466 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1467 1468 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1469 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1470 1471 return page; 1472 } 1473 1474 /* NUMA hinting page fault entry point for trans huge pmds */ 1475 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) 1476 { 1477 struct vm_area_struct *vma = vmf->vma; 1478 pmd_t oldpmd = vmf->orig_pmd; 1479 pmd_t pmd; 1480 struct page *page; 1481 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1482 int page_nid = NUMA_NO_NODE; 1483 int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK); 1484 bool migrated = false; 1485 bool was_writable = pmd_savedwrite(oldpmd); 1486 int flags = 0; 1487 1488 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1489 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1490 spin_unlock(vmf->ptl); 1491 goto out; 1492 } 1493 1494 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1495 page = vm_normal_page_pmd(vma, haddr, pmd); 1496 if (!page) 1497 goto out_map; 1498 1499 /* See similar comment in do_numa_page for explanation */ 1500 if (!was_writable) 1501 flags |= TNF_NO_GROUP; 1502 1503 page_nid = page_to_nid(page); 1504 /* 1505 * For memory tiering mode, cpupid of slow memory page is used 1506 * to record page access time. So use default value. 1507 */ 1508 if (node_is_toptier(page_nid)) 1509 last_cpupid = page_cpupid_last(page); 1510 target_nid = numa_migrate_prep(page, vma, haddr, page_nid, 1511 &flags); 1512 1513 if (target_nid == NUMA_NO_NODE) { 1514 put_page(page); 1515 goto out_map; 1516 } 1517 1518 spin_unlock(vmf->ptl); 1519 1520 migrated = migrate_misplaced_page(page, vma, target_nid); 1521 if (migrated) { 1522 flags |= TNF_MIGRATED; 1523 page_nid = target_nid; 1524 } else { 1525 flags |= TNF_MIGRATE_FAIL; 1526 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1527 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1528 spin_unlock(vmf->ptl); 1529 goto out; 1530 } 1531 goto out_map; 1532 } 1533 1534 out: 1535 if (page_nid != NUMA_NO_NODE) 1536 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1537 flags); 1538 1539 return 0; 1540 1541 out_map: 1542 /* Restore the PMD */ 1543 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1544 pmd = pmd_mkyoung(pmd); 1545 if (was_writable) 1546 pmd = pmd_mkwrite(pmd); 1547 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1548 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1549 spin_unlock(vmf->ptl); 1550 goto out; 1551 } 1552 1553 /* 1554 * Return true if we do MADV_FREE successfully on entire pmd page. 1555 * Otherwise, return false. 1556 */ 1557 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1558 pmd_t *pmd, unsigned long addr, unsigned long next) 1559 { 1560 spinlock_t *ptl; 1561 pmd_t orig_pmd; 1562 struct page *page; 1563 struct mm_struct *mm = tlb->mm; 1564 bool ret = false; 1565 1566 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1567 1568 ptl = pmd_trans_huge_lock(pmd, vma); 1569 if (!ptl) 1570 goto out_unlocked; 1571 1572 orig_pmd = *pmd; 1573 if (is_huge_zero_pmd(orig_pmd)) 1574 goto out; 1575 1576 if (unlikely(!pmd_present(orig_pmd))) { 1577 VM_BUG_ON(thp_migration_supported() && 1578 !is_pmd_migration_entry(orig_pmd)); 1579 goto out; 1580 } 1581 1582 page = pmd_page(orig_pmd); 1583 /* 1584 * If other processes are mapping this page, we couldn't discard 1585 * the page unless they all do MADV_FREE so let's skip the page. 1586 */ 1587 if (total_mapcount(page) != 1) 1588 goto out; 1589 1590 if (!trylock_page(page)) 1591 goto out; 1592 1593 /* 1594 * If user want to discard part-pages of THP, split it so MADV_FREE 1595 * will deactivate only them. 1596 */ 1597 if (next - addr != HPAGE_PMD_SIZE) { 1598 get_page(page); 1599 spin_unlock(ptl); 1600 split_huge_page(page); 1601 unlock_page(page); 1602 put_page(page); 1603 goto out_unlocked; 1604 } 1605 1606 if (PageDirty(page)) 1607 ClearPageDirty(page); 1608 unlock_page(page); 1609 1610 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1611 pmdp_invalidate(vma, addr, pmd); 1612 orig_pmd = pmd_mkold(orig_pmd); 1613 orig_pmd = pmd_mkclean(orig_pmd); 1614 1615 set_pmd_at(mm, addr, pmd, orig_pmd); 1616 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1617 } 1618 1619 mark_page_lazyfree(page); 1620 ret = true; 1621 out: 1622 spin_unlock(ptl); 1623 out_unlocked: 1624 return ret; 1625 } 1626 1627 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1628 { 1629 pgtable_t pgtable; 1630 1631 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1632 pte_free(mm, pgtable); 1633 mm_dec_nr_ptes(mm); 1634 } 1635 1636 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1637 pmd_t *pmd, unsigned long addr) 1638 { 1639 pmd_t orig_pmd; 1640 spinlock_t *ptl; 1641 1642 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1643 1644 ptl = __pmd_trans_huge_lock(pmd, vma); 1645 if (!ptl) 1646 return 0; 1647 /* 1648 * For architectures like ppc64 we look at deposited pgtable 1649 * when calling pmdp_huge_get_and_clear. So do the 1650 * pgtable_trans_huge_withdraw after finishing pmdp related 1651 * operations. 1652 */ 1653 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1654 tlb->fullmm); 1655 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1656 if (vma_is_special_huge(vma)) { 1657 if (arch_needs_pgtable_deposit()) 1658 zap_deposited_table(tlb->mm, pmd); 1659 spin_unlock(ptl); 1660 } else if (is_huge_zero_pmd(orig_pmd)) { 1661 zap_deposited_table(tlb->mm, pmd); 1662 spin_unlock(ptl); 1663 } else { 1664 struct page *page = NULL; 1665 int flush_needed = 1; 1666 1667 if (pmd_present(orig_pmd)) { 1668 page = pmd_page(orig_pmd); 1669 page_remove_rmap(page, vma, true); 1670 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1671 VM_BUG_ON_PAGE(!PageHead(page), page); 1672 } else if (thp_migration_supported()) { 1673 swp_entry_t entry; 1674 1675 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1676 entry = pmd_to_swp_entry(orig_pmd); 1677 page = pfn_swap_entry_to_page(entry); 1678 flush_needed = 0; 1679 } else 1680 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1681 1682 if (PageAnon(page)) { 1683 zap_deposited_table(tlb->mm, pmd); 1684 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1685 } else { 1686 if (arch_needs_pgtable_deposit()) 1687 zap_deposited_table(tlb->mm, pmd); 1688 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1689 } 1690 1691 spin_unlock(ptl); 1692 if (flush_needed) 1693 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1694 } 1695 return 1; 1696 } 1697 1698 #ifndef pmd_move_must_withdraw 1699 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1700 spinlock_t *old_pmd_ptl, 1701 struct vm_area_struct *vma) 1702 { 1703 /* 1704 * With split pmd lock we also need to move preallocated 1705 * PTE page table if new_pmd is on different PMD page table. 1706 * 1707 * We also don't deposit and withdraw tables for file pages. 1708 */ 1709 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1710 } 1711 #endif 1712 1713 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1714 { 1715 #ifdef CONFIG_MEM_SOFT_DIRTY 1716 if (unlikely(is_pmd_migration_entry(pmd))) 1717 pmd = pmd_swp_mksoft_dirty(pmd); 1718 else if (pmd_present(pmd)) 1719 pmd = pmd_mksoft_dirty(pmd); 1720 #endif 1721 return pmd; 1722 } 1723 1724 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1725 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1726 { 1727 spinlock_t *old_ptl, *new_ptl; 1728 pmd_t pmd; 1729 struct mm_struct *mm = vma->vm_mm; 1730 bool force_flush = false; 1731 1732 /* 1733 * The destination pmd shouldn't be established, free_pgtables() 1734 * should have release it. 1735 */ 1736 if (WARN_ON(!pmd_none(*new_pmd))) { 1737 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1738 return false; 1739 } 1740 1741 /* 1742 * We don't have to worry about the ordering of src and dst 1743 * ptlocks because exclusive mmap_lock prevents deadlock. 1744 */ 1745 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1746 if (old_ptl) { 1747 new_ptl = pmd_lockptr(mm, new_pmd); 1748 if (new_ptl != old_ptl) 1749 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1750 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1751 if (pmd_present(pmd)) 1752 force_flush = true; 1753 VM_BUG_ON(!pmd_none(*new_pmd)); 1754 1755 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1756 pgtable_t pgtable; 1757 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1758 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1759 } 1760 pmd = move_soft_dirty_pmd(pmd); 1761 set_pmd_at(mm, new_addr, new_pmd, pmd); 1762 if (force_flush) 1763 flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1764 if (new_ptl != old_ptl) 1765 spin_unlock(new_ptl); 1766 spin_unlock(old_ptl); 1767 return true; 1768 } 1769 return false; 1770 } 1771 1772 /* 1773 * Returns 1774 * - 0 if PMD could not be locked 1775 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary 1776 * or if prot_numa but THP migration is not supported 1777 * - HPAGE_PMD_NR if protections changed and TLB flush necessary 1778 */ 1779 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1780 pmd_t *pmd, unsigned long addr, pgprot_t newprot, 1781 unsigned long cp_flags) 1782 { 1783 struct mm_struct *mm = vma->vm_mm; 1784 spinlock_t *ptl; 1785 pmd_t oldpmd, entry; 1786 bool preserve_write; 1787 int ret; 1788 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1789 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1790 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1791 1792 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1793 1794 if (prot_numa && !thp_migration_supported()) 1795 return 1; 1796 1797 ptl = __pmd_trans_huge_lock(pmd, vma); 1798 if (!ptl) 1799 return 0; 1800 1801 preserve_write = prot_numa && pmd_write(*pmd); 1802 ret = 1; 1803 1804 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1805 if (is_swap_pmd(*pmd)) { 1806 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1807 struct page *page = pfn_swap_entry_to_page(entry); 1808 1809 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1810 if (is_writable_migration_entry(entry)) { 1811 pmd_t newpmd; 1812 /* 1813 * A protection check is difficult so 1814 * just be safe and disable write 1815 */ 1816 if (PageAnon(page)) 1817 entry = make_readable_exclusive_migration_entry(swp_offset(entry)); 1818 else 1819 entry = make_readable_migration_entry(swp_offset(entry)); 1820 newpmd = swp_entry_to_pmd(entry); 1821 if (pmd_swp_soft_dirty(*pmd)) 1822 newpmd = pmd_swp_mksoft_dirty(newpmd); 1823 if (pmd_swp_uffd_wp(*pmd)) 1824 newpmd = pmd_swp_mkuffd_wp(newpmd); 1825 set_pmd_at(mm, addr, pmd, newpmd); 1826 } 1827 goto unlock; 1828 } 1829 #endif 1830 1831 if (prot_numa) { 1832 struct page *page; 1833 bool toptier; 1834 /* 1835 * Avoid trapping faults against the zero page. The read-only 1836 * data is likely to be read-cached on the local CPU and 1837 * local/remote hits to the zero page are not interesting. 1838 */ 1839 if (is_huge_zero_pmd(*pmd)) 1840 goto unlock; 1841 1842 if (pmd_protnone(*pmd)) 1843 goto unlock; 1844 1845 page = pmd_page(*pmd); 1846 toptier = node_is_toptier(page_to_nid(page)); 1847 /* 1848 * Skip scanning top tier node if normal numa 1849 * balancing is disabled 1850 */ 1851 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 1852 toptier) 1853 goto unlock; 1854 1855 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING && 1856 !toptier) 1857 xchg_page_access_time(page, jiffies_to_msecs(jiffies)); 1858 } 1859 /* 1860 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 1861 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1862 * which is also under mmap_read_lock(mm): 1863 * 1864 * CPU0: CPU1: 1865 * change_huge_pmd(prot_numa=1) 1866 * pmdp_huge_get_and_clear_notify() 1867 * madvise_dontneed() 1868 * zap_pmd_range() 1869 * pmd_trans_huge(*pmd) == 0 (without ptl) 1870 * // skip the pmd 1871 * set_pmd_at(); 1872 * // pmd is re-established 1873 * 1874 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1875 * which may break userspace. 1876 * 1877 * pmdp_invalidate_ad() is required to make sure we don't miss 1878 * dirty/young flags set by hardware. 1879 */ 1880 oldpmd = pmdp_invalidate_ad(vma, addr, pmd); 1881 1882 entry = pmd_modify(oldpmd, newprot); 1883 if (preserve_write) 1884 entry = pmd_mk_savedwrite(entry); 1885 if (uffd_wp) { 1886 entry = pmd_wrprotect(entry); 1887 entry = pmd_mkuffd_wp(entry); 1888 } else if (uffd_wp_resolve) { 1889 /* 1890 * Leave the write bit to be handled by PF interrupt 1891 * handler, then things like COW could be properly 1892 * handled. 1893 */ 1894 entry = pmd_clear_uffd_wp(entry); 1895 } 1896 ret = HPAGE_PMD_NR; 1897 set_pmd_at(mm, addr, pmd, entry); 1898 1899 if (huge_pmd_needs_flush(oldpmd, entry)) 1900 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); 1901 1902 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); 1903 unlock: 1904 spin_unlock(ptl); 1905 return ret; 1906 } 1907 1908 /* 1909 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1910 * 1911 * Note that if it returns page table lock pointer, this routine returns without 1912 * unlocking page table lock. So callers must unlock it. 1913 */ 1914 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1915 { 1916 spinlock_t *ptl; 1917 ptl = pmd_lock(vma->vm_mm, pmd); 1918 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 1919 pmd_devmap(*pmd))) 1920 return ptl; 1921 spin_unlock(ptl); 1922 return NULL; 1923 } 1924 1925 /* 1926 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. 1927 * 1928 * Note that if it returns page table lock pointer, this routine returns without 1929 * unlocking page table lock. So callers must unlock it. 1930 */ 1931 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 1932 { 1933 spinlock_t *ptl; 1934 1935 ptl = pud_lock(vma->vm_mm, pud); 1936 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 1937 return ptl; 1938 spin_unlock(ptl); 1939 return NULL; 1940 } 1941 1942 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1943 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 1944 pud_t *pud, unsigned long addr) 1945 { 1946 spinlock_t *ptl; 1947 1948 ptl = __pud_trans_huge_lock(pud, vma); 1949 if (!ptl) 1950 return 0; 1951 1952 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 1953 tlb_remove_pud_tlb_entry(tlb, pud, addr); 1954 if (vma_is_special_huge(vma)) { 1955 spin_unlock(ptl); 1956 /* No zero page support yet */ 1957 } else { 1958 /* No support for anonymous PUD pages yet */ 1959 BUG(); 1960 } 1961 return 1; 1962 } 1963 1964 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 1965 unsigned long haddr) 1966 { 1967 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 1968 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 1969 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 1970 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 1971 1972 count_vm_event(THP_SPLIT_PUD); 1973 1974 pudp_huge_clear_flush_notify(vma, haddr, pud); 1975 } 1976 1977 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 1978 unsigned long address) 1979 { 1980 spinlock_t *ptl; 1981 struct mmu_notifier_range range; 1982 1983 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1984 address & HPAGE_PUD_MASK, 1985 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 1986 mmu_notifier_invalidate_range_start(&range); 1987 ptl = pud_lock(vma->vm_mm, pud); 1988 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 1989 goto out; 1990 __split_huge_pud_locked(vma, pud, range.start); 1991 1992 out: 1993 spin_unlock(ptl); 1994 /* 1995 * No need to double call mmu_notifier->invalidate_range() callback as 1996 * the above pudp_huge_clear_flush_notify() did already call it. 1997 */ 1998 mmu_notifier_invalidate_range_only_end(&range); 1999 } 2000 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 2001 2002 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2003 unsigned long haddr, pmd_t *pmd) 2004 { 2005 struct mm_struct *mm = vma->vm_mm; 2006 pgtable_t pgtable; 2007 pmd_t _pmd; 2008 int i; 2009 2010 /* 2011 * Leave pmd empty until pte is filled note that it is fine to delay 2012 * notification until mmu_notifier_invalidate_range_end() as we are 2013 * replacing a zero pmd write protected page with a zero pte write 2014 * protected page. 2015 * 2016 * See Documentation/mm/mmu_notifier.rst 2017 */ 2018 pmdp_huge_clear_flush(vma, haddr, pmd); 2019 2020 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2021 pmd_populate(mm, &_pmd, pgtable); 2022 2023 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 2024 pte_t *pte, entry; 2025 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 2026 entry = pte_mkspecial(entry); 2027 pte = pte_offset_map(&_pmd, haddr); 2028 VM_BUG_ON(!pte_none(*pte)); 2029 set_pte_at(mm, haddr, pte, entry); 2030 pte_unmap(pte); 2031 } 2032 smp_wmb(); /* make pte visible before pmd */ 2033 pmd_populate(mm, pmd, pgtable); 2034 } 2035 2036 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2037 unsigned long haddr, bool freeze) 2038 { 2039 struct mm_struct *mm = vma->vm_mm; 2040 struct page *page; 2041 pgtable_t pgtable; 2042 pmd_t old_pmd, _pmd; 2043 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 2044 bool anon_exclusive = false, dirty = false; 2045 unsigned long addr; 2046 int i; 2047 2048 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2049 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2050 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2051 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2052 && !pmd_devmap(*pmd)); 2053 2054 count_vm_event(THP_SPLIT_PMD); 2055 2056 if (!vma_is_anonymous(vma)) { 2057 old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 2058 /* 2059 * We are going to unmap this huge page. So 2060 * just go ahead and zap it 2061 */ 2062 if (arch_needs_pgtable_deposit()) 2063 zap_deposited_table(mm, pmd); 2064 if (vma_is_special_huge(vma)) 2065 return; 2066 if (unlikely(is_pmd_migration_entry(old_pmd))) { 2067 swp_entry_t entry; 2068 2069 entry = pmd_to_swp_entry(old_pmd); 2070 page = pfn_swap_entry_to_page(entry); 2071 } else { 2072 page = pmd_page(old_pmd); 2073 if (!PageDirty(page) && pmd_dirty(old_pmd)) 2074 set_page_dirty(page); 2075 if (!PageReferenced(page) && pmd_young(old_pmd)) 2076 SetPageReferenced(page); 2077 page_remove_rmap(page, vma, true); 2078 put_page(page); 2079 } 2080 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2081 return; 2082 } 2083 2084 if (is_huge_zero_pmd(*pmd)) { 2085 /* 2086 * FIXME: Do we want to invalidate secondary mmu by calling 2087 * mmu_notifier_invalidate_range() see comments below inside 2088 * __split_huge_pmd() ? 2089 * 2090 * We are going from a zero huge page write protected to zero 2091 * small page also write protected so it does not seems useful 2092 * to invalidate secondary mmu at this time. 2093 */ 2094 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2095 } 2096 2097 /* 2098 * Up to this point the pmd is present and huge and userland has the 2099 * whole access to the hugepage during the split (which happens in 2100 * place). If we overwrite the pmd with the not-huge version pointing 2101 * to the pte here (which of course we could if all CPUs were bug 2102 * free), userland could trigger a small page size TLB miss on the 2103 * small sized TLB while the hugepage TLB entry is still established in 2104 * the huge TLB. Some CPU doesn't like that. 2105 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2106 * 383 on page 105. Intel should be safe but is also warns that it's 2107 * only safe if the permission and cache attributes of the two entries 2108 * loaded in the two TLB is identical (which should be the case here). 2109 * But it is generally safer to never allow small and huge TLB entries 2110 * for the same virtual address to be loaded simultaneously. So instead 2111 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2112 * current pmd notpresent (atomically because here the pmd_trans_huge 2113 * must remain set at all times on the pmd until the split is complete 2114 * for this pmd), then we flush the SMP TLB and finally we write the 2115 * non-huge version of the pmd entry with pmd_populate. 2116 */ 2117 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2118 2119 pmd_migration = is_pmd_migration_entry(old_pmd); 2120 if (unlikely(pmd_migration)) { 2121 swp_entry_t entry; 2122 2123 entry = pmd_to_swp_entry(old_pmd); 2124 page = pfn_swap_entry_to_page(entry); 2125 write = is_writable_migration_entry(entry); 2126 if (PageAnon(page)) 2127 anon_exclusive = is_readable_exclusive_migration_entry(entry); 2128 young = is_migration_entry_young(entry); 2129 dirty = is_migration_entry_dirty(entry); 2130 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2131 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2132 } else { 2133 page = pmd_page(old_pmd); 2134 if (pmd_dirty(old_pmd)) { 2135 dirty = true; 2136 SetPageDirty(page); 2137 } 2138 write = pmd_write(old_pmd); 2139 young = pmd_young(old_pmd); 2140 soft_dirty = pmd_soft_dirty(old_pmd); 2141 uffd_wp = pmd_uffd_wp(old_pmd); 2142 2143 VM_BUG_ON_PAGE(!page_count(page), page); 2144 page_ref_add(page, HPAGE_PMD_NR - 1); 2145 2146 /* 2147 * Without "freeze", we'll simply split the PMD, propagating the 2148 * PageAnonExclusive() flag for each PTE by setting it for 2149 * each subpage -- no need to (temporarily) clear. 2150 * 2151 * With "freeze" we want to replace mapped pages by 2152 * migration entries right away. This is only possible if we 2153 * managed to clear PageAnonExclusive() -- see 2154 * set_pmd_migration_entry(). 2155 * 2156 * In case we cannot clear PageAnonExclusive(), split the PMD 2157 * only and let try_to_migrate_one() fail later. 2158 * 2159 * See page_try_share_anon_rmap(): invalidate PMD first. 2160 */ 2161 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 2162 if (freeze && anon_exclusive && page_try_share_anon_rmap(page)) 2163 freeze = false; 2164 } 2165 2166 /* 2167 * Withdraw the table only after we mark the pmd entry invalid. 2168 * This's critical for some architectures (Power). 2169 */ 2170 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2171 pmd_populate(mm, &_pmd, pgtable); 2172 2173 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2174 pte_t entry, *pte; 2175 /* 2176 * Note that NUMA hinting access restrictions are not 2177 * transferred to avoid any possibility of altering 2178 * permissions across VMAs. 2179 */ 2180 if (freeze || pmd_migration) { 2181 swp_entry_t swp_entry; 2182 if (write) 2183 swp_entry = make_writable_migration_entry( 2184 page_to_pfn(page + i)); 2185 else if (anon_exclusive) 2186 swp_entry = make_readable_exclusive_migration_entry( 2187 page_to_pfn(page + i)); 2188 else 2189 swp_entry = make_readable_migration_entry( 2190 page_to_pfn(page + i)); 2191 if (young) 2192 swp_entry = make_migration_entry_young(swp_entry); 2193 if (dirty) 2194 swp_entry = make_migration_entry_dirty(swp_entry); 2195 entry = swp_entry_to_pte(swp_entry); 2196 if (soft_dirty) 2197 entry = pte_swp_mksoft_dirty(entry); 2198 if (uffd_wp) 2199 entry = pte_swp_mkuffd_wp(entry); 2200 } else { 2201 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2202 entry = maybe_mkwrite(entry, vma); 2203 if (anon_exclusive) 2204 SetPageAnonExclusive(page + i); 2205 if (!write) 2206 entry = pte_wrprotect(entry); 2207 if (!young) 2208 entry = pte_mkold(entry); 2209 /* NOTE: this may set soft-dirty too on some archs */ 2210 if (dirty) 2211 entry = pte_mkdirty(entry); 2212 if (soft_dirty) 2213 entry = pte_mksoft_dirty(entry); 2214 if (uffd_wp) 2215 entry = pte_mkuffd_wp(entry); 2216 } 2217 pte = pte_offset_map(&_pmd, addr); 2218 BUG_ON(!pte_none(*pte)); 2219 set_pte_at(mm, addr, pte, entry); 2220 if (!pmd_migration) 2221 atomic_inc(&page[i]._mapcount); 2222 pte_unmap(pte); 2223 } 2224 2225 if (!pmd_migration) { 2226 /* 2227 * Set PG_double_map before dropping compound_mapcount to avoid 2228 * false-negative page_mapped(). 2229 */ 2230 if (compound_mapcount(page) > 1 && 2231 !TestSetPageDoubleMap(page)) { 2232 for (i = 0; i < HPAGE_PMD_NR; i++) 2233 atomic_inc(&page[i]._mapcount); 2234 } 2235 2236 lock_page_memcg(page); 2237 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { 2238 /* Last compound_mapcount is gone. */ 2239 __mod_lruvec_page_state(page, NR_ANON_THPS, 2240 -HPAGE_PMD_NR); 2241 if (TestClearPageDoubleMap(page)) { 2242 /* No need in mapcount reference anymore */ 2243 for (i = 0; i < HPAGE_PMD_NR; i++) 2244 atomic_dec(&page[i]._mapcount); 2245 } 2246 } 2247 unlock_page_memcg(page); 2248 2249 /* Above is effectively page_remove_rmap(page, vma, true) */ 2250 munlock_vma_page(page, vma, true); 2251 } 2252 2253 smp_wmb(); /* make pte visible before pmd */ 2254 pmd_populate(mm, pmd, pgtable); 2255 2256 if (freeze) { 2257 for (i = 0; i < HPAGE_PMD_NR; i++) { 2258 page_remove_rmap(page + i, vma, false); 2259 put_page(page + i); 2260 } 2261 } 2262 } 2263 2264 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2265 unsigned long address, bool freeze, struct folio *folio) 2266 { 2267 spinlock_t *ptl; 2268 struct mmu_notifier_range range; 2269 2270 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2271 address & HPAGE_PMD_MASK, 2272 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2273 mmu_notifier_invalidate_range_start(&range); 2274 ptl = pmd_lock(vma->vm_mm, pmd); 2275 2276 /* 2277 * If caller asks to setup a migration entry, we need a folio to check 2278 * pmd against. Otherwise we can end up replacing wrong folio. 2279 */ 2280 VM_BUG_ON(freeze && !folio); 2281 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); 2282 2283 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || 2284 is_pmd_migration_entry(*pmd)) { 2285 /* 2286 * It's safe to call pmd_page when folio is set because it's 2287 * guaranteed that pmd is present. 2288 */ 2289 if (folio && folio != page_folio(pmd_page(*pmd))) 2290 goto out; 2291 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2292 } 2293 2294 out: 2295 spin_unlock(ptl); 2296 /* 2297 * No need to double call mmu_notifier->invalidate_range() callback. 2298 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2299 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2300 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2301 * fault will trigger a flush_notify before pointing to a new page 2302 * (it is fine if the secondary mmu keeps pointing to the old zero 2303 * page in the meantime) 2304 * 3) Split a huge pmd into pte pointing to the same page. No need 2305 * to invalidate secondary tlb entry they are all still valid. 2306 * any further changes to individual pte will notify. So no need 2307 * to call mmu_notifier->invalidate_range() 2308 */ 2309 mmu_notifier_invalidate_range_only_end(&range); 2310 } 2311 2312 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2313 bool freeze, struct folio *folio) 2314 { 2315 pmd_t *pmd = mm_find_pmd(vma->vm_mm, address); 2316 2317 if (!pmd) 2318 return; 2319 2320 __split_huge_pmd(vma, pmd, address, freeze, folio); 2321 } 2322 2323 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) 2324 { 2325 /* 2326 * If the new address isn't hpage aligned and it could previously 2327 * contain an hugepage: check if we need to split an huge pmd. 2328 */ 2329 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && 2330 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), 2331 ALIGN(address, HPAGE_PMD_SIZE))) 2332 split_huge_pmd_address(vma, address, false, NULL); 2333 } 2334 2335 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2336 unsigned long start, 2337 unsigned long end, 2338 long adjust_next) 2339 { 2340 /* Check if we need to split start first. */ 2341 split_huge_pmd_if_needed(vma, start); 2342 2343 /* Check if we need to split end next. */ 2344 split_huge_pmd_if_needed(vma, end); 2345 2346 /* 2347 * If we're also updating the next vma vm_start, 2348 * check if we need to split it. 2349 */ 2350 if (adjust_next > 0) { 2351 struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end); 2352 unsigned long nstart = next->vm_start; 2353 nstart += adjust_next; 2354 split_huge_pmd_if_needed(next, nstart); 2355 } 2356 } 2357 2358 static void unmap_folio(struct folio *folio) 2359 { 2360 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | 2361 TTU_SYNC; 2362 2363 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 2364 2365 /* 2366 * Anon pages need migration entries to preserve them, but file 2367 * pages can simply be left unmapped, then faulted back on demand. 2368 * If that is ever changed (perhaps for mlock), update remap_page(). 2369 */ 2370 if (folio_test_anon(folio)) 2371 try_to_migrate(folio, ttu_flags); 2372 else 2373 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); 2374 } 2375 2376 static void remap_page(struct folio *folio, unsigned long nr) 2377 { 2378 int i = 0; 2379 2380 /* If unmap_folio() uses try_to_migrate() on file, remove this check */ 2381 if (!folio_test_anon(folio)) 2382 return; 2383 for (;;) { 2384 remove_migration_ptes(folio, folio, true); 2385 i += folio_nr_pages(folio); 2386 if (i >= nr) 2387 break; 2388 folio = folio_next(folio); 2389 } 2390 } 2391 2392 static void lru_add_page_tail(struct page *head, struct page *tail, 2393 struct lruvec *lruvec, struct list_head *list) 2394 { 2395 VM_BUG_ON_PAGE(!PageHead(head), head); 2396 VM_BUG_ON_PAGE(PageCompound(tail), head); 2397 VM_BUG_ON_PAGE(PageLRU(tail), head); 2398 lockdep_assert_held(&lruvec->lru_lock); 2399 2400 if (list) { 2401 /* page reclaim is reclaiming a huge page */ 2402 VM_WARN_ON(PageLRU(head)); 2403 get_page(tail); 2404 list_add_tail(&tail->lru, list); 2405 } else { 2406 /* head is still on lru (and we have it frozen) */ 2407 VM_WARN_ON(!PageLRU(head)); 2408 if (PageUnevictable(tail)) 2409 tail->mlock_count = 0; 2410 else 2411 list_add_tail(&tail->lru, &head->lru); 2412 SetPageLRU(tail); 2413 } 2414 } 2415 2416 static void __split_huge_page_tail(struct page *head, int tail, 2417 struct lruvec *lruvec, struct list_head *list) 2418 { 2419 struct page *page_tail = head + tail; 2420 2421 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2422 2423 /* 2424 * Clone page flags before unfreezing refcount. 2425 * 2426 * After successful get_page_unless_zero() might follow flags change, 2427 * for example lock_page() which set PG_waiters. 2428 * 2429 * Note that for mapped sub-pages of an anonymous THP, 2430 * PG_anon_exclusive has been cleared in unmap_folio() and is stored in 2431 * the migration entry instead from where remap_page() will restore it. 2432 * We can still have PG_anon_exclusive set on effectively unmapped and 2433 * unreferenced sub-pages of an anonymous THP: we can simply drop 2434 * PG_anon_exclusive (-> PG_mappedtodisk) for these here. 2435 */ 2436 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2437 page_tail->flags |= (head->flags & 2438 ((1L << PG_referenced) | 2439 (1L << PG_swapbacked) | 2440 (1L << PG_swapcache) | 2441 (1L << PG_mlocked) | 2442 (1L << PG_uptodate) | 2443 (1L << PG_active) | 2444 (1L << PG_workingset) | 2445 (1L << PG_locked) | 2446 (1L << PG_unevictable) | 2447 #ifdef CONFIG_64BIT 2448 (1L << PG_arch_2) | 2449 #endif 2450 (1L << PG_dirty) | 2451 LRU_GEN_MASK | LRU_REFS_MASK)); 2452 2453 /* ->mapping in first tail page is compound_mapcount */ 2454 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2455 page_tail); 2456 page_tail->mapping = head->mapping; 2457 page_tail->index = head->index + tail; 2458 2459 /* 2460 * page->private should not be set in tail pages with the exception 2461 * of swap cache pages that store the swp_entry_t in tail pages. 2462 * Fix up and warn once if private is unexpectedly set. 2463 */ 2464 if (!folio_test_swapcache(page_folio(head))) { 2465 VM_WARN_ON_ONCE_PAGE(page_tail->private != 0, page_tail); 2466 page_tail->private = 0; 2467 } 2468 2469 /* Page flags must be visible before we make the page non-compound. */ 2470 smp_wmb(); 2471 2472 /* 2473 * Clear PageTail before unfreezing page refcount. 2474 * 2475 * After successful get_page_unless_zero() might follow put_page() 2476 * which needs correct compound_head(). 2477 */ 2478 clear_compound_head(page_tail); 2479 2480 /* Finally unfreeze refcount. Additional reference from page cache. */ 2481 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2482 PageSwapCache(head))); 2483 2484 if (page_is_young(head)) 2485 set_page_young(page_tail); 2486 if (page_is_idle(head)) 2487 set_page_idle(page_tail); 2488 2489 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2490 2491 /* 2492 * always add to the tail because some iterators expect new 2493 * pages to show after the currently processed elements - e.g. 2494 * migrate_pages 2495 */ 2496 lru_add_page_tail(head, page_tail, lruvec, list); 2497 } 2498 2499 static void __split_huge_page(struct page *page, struct list_head *list, 2500 pgoff_t end) 2501 { 2502 struct folio *folio = page_folio(page); 2503 struct page *head = &folio->page; 2504 struct lruvec *lruvec; 2505 struct address_space *swap_cache = NULL; 2506 unsigned long offset = 0; 2507 unsigned int nr = thp_nr_pages(head); 2508 int i; 2509 2510 /* complete memcg works before add pages to LRU */ 2511 split_page_memcg(head, nr); 2512 2513 if (PageAnon(head) && PageSwapCache(head)) { 2514 swp_entry_t entry = { .val = page_private(head) }; 2515 2516 offset = swp_offset(entry); 2517 swap_cache = swap_address_space(entry); 2518 xa_lock(&swap_cache->i_pages); 2519 } 2520 2521 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ 2522 lruvec = folio_lruvec_lock(folio); 2523 2524 ClearPageHasHWPoisoned(head); 2525 2526 for (i = nr - 1; i >= 1; i--) { 2527 __split_huge_page_tail(head, i, lruvec, list); 2528 /* Some pages can be beyond EOF: drop them from page cache */ 2529 if (head[i].index >= end) { 2530 struct folio *tail = page_folio(head + i); 2531 2532 if (shmem_mapping(head->mapping)) 2533 shmem_uncharge(head->mapping->host, 1); 2534 else if (folio_test_clear_dirty(tail)) 2535 folio_account_cleaned(tail, 2536 inode_to_wb(folio->mapping->host)); 2537 __filemap_remove_folio(tail, NULL); 2538 folio_put(tail); 2539 } else if (!PageAnon(page)) { 2540 __xa_store(&head->mapping->i_pages, head[i].index, 2541 head + i, 0); 2542 } else if (swap_cache) { 2543 __xa_store(&swap_cache->i_pages, offset + i, 2544 head + i, 0); 2545 } 2546 } 2547 2548 ClearPageCompound(head); 2549 unlock_page_lruvec(lruvec); 2550 /* Caller disabled irqs, so they are still disabled here */ 2551 2552 split_page_owner(head, nr); 2553 2554 /* See comment in __split_huge_page_tail() */ 2555 if (PageAnon(head)) { 2556 /* Additional pin to swap cache */ 2557 if (PageSwapCache(head)) { 2558 page_ref_add(head, 2); 2559 xa_unlock(&swap_cache->i_pages); 2560 } else { 2561 page_ref_inc(head); 2562 } 2563 } else { 2564 /* Additional pin to page cache */ 2565 page_ref_add(head, 2); 2566 xa_unlock(&head->mapping->i_pages); 2567 } 2568 local_irq_enable(); 2569 2570 remap_page(folio, nr); 2571 2572 if (PageSwapCache(head)) { 2573 swp_entry_t entry = { .val = page_private(head) }; 2574 2575 split_swap_cluster(entry); 2576 } 2577 2578 for (i = 0; i < nr; i++) { 2579 struct page *subpage = head + i; 2580 if (subpage == page) 2581 continue; 2582 unlock_page(subpage); 2583 2584 /* 2585 * Subpages may be freed if there wasn't any mapping 2586 * like if add_to_swap() is running on a lru page that 2587 * had its mapping zapped. And freeing these pages 2588 * requires taking the lru_lock so we do the put_page 2589 * of the tail pages after the split is complete. 2590 */ 2591 free_page_and_swap_cache(subpage); 2592 } 2593 } 2594 2595 /* Racy check whether the huge page can be split */ 2596 bool can_split_folio(struct folio *folio, int *pextra_pins) 2597 { 2598 int extra_pins; 2599 2600 /* Additional pins from page cache */ 2601 if (folio_test_anon(folio)) 2602 extra_pins = folio_test_swapcache(folio) ? 2603 folio_nr_pages(folio) : 0; 2604 else 2605 extra_pins = folio_nr_pages(folio); 2606 if (pextra_pins) 2607 *pextra_pins = extra_pins; 2608 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1; 2609 } 2610 2611 /* 2612 * This function splits huge page into normal pages. @page can point to any 2613 * subpage of huge page to split. Split doesn't change the position of @page. 2614 * 2615 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2616 * The huge page must be locked. 2617 * 2618 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2619 * 2620 * Both head page and tail pages will inherit mapping, flags, and so on from 2621 * the hugepage. 2622 * 2623 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2624 * they are not mapped. 2625 * 2626 * Returns 0 if the hugepage is split successfully. 2627 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2628 * us. 2629 */ 2630 int split_huge_page_to_list(struct page *page, struct list_head *list) 2631 { 2632 struct folio *folio = page_folio(page); 2633 struct deferred_split *ds_queue = get_deferred_split_queue(&folio->page); 2634 XA_STATE(xas, &folio->mapping->i_pages, folio->index); 2635 struct anon_vma *anon_vma = NULL; 2636 struct address_space *mapping = NULL; 2637 int extra_pins, ret; 2638 pgoff_t end; 2639 bool is_hzp; 2640 2641 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); 2642 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 2643 2644 is_hzp = is_huge_zero_page(&folio->page); 2645 VM_WARN_ON_ONCE_FOLIO(is_hzp, folio); 2646 if (is_hzp) 2647 return -EBUSY; 2648 2649 if (folio_test_writeback(folio)) 2650 return -EBUSY; 2651 2652 if (folio_test_anon(folio)) { 2653 /* 2654 * The caller does not necessarily hold an mmap_lock that would 2655 * prevent the anon_vma disappearing so we first we take a 2656 * reference to it and then lock the anon_vma for write. This 2657 * is similar to folio_lock_anon_vma_read except the write lock 2658 * is taken to serialise against parallel split or collapse 2659 * operations. 2660 */ 2661 anon_vma = folio_get_anon_vma(folio); 2662 if (!anon_vma) { 2663 ret = -EBUSY; 2664 goto out; 2665 } 2666 end = -1; 2667 mapping = NULL; 2668 anon_vma_lock_write(anon_vma); 2669 } else { 2670 gfp_t gfp; 2671 2672 mapping = folio->mapping; 2673 2674 /* Truncated ? */ 2675 if (!mapping) { 2676 ret = -EBUSY; 2677 goto out; 2678 } 2679 2680 gfp = current_gfp_context(mapping_gfp_mask(mapping) & 2681 GFP_RECLAIM_MASK); 2682 2683 if (folio_test_private(folio) && 2684 !filemap_release_folio(folio, gfp)) { 2685 ret = -EBUSY; 2686 goto out; 2687 } 2688 2689 xas_split_alloc(&xas, folio, folio_order(folio), gfp); 2690 if (xas_error(&xas)) { 2691 ret = xas_error(&xas); 2692 goto out; 2693 } 2694 2695 anon_vma = NULL; 2696 i_mmap_lock_read(mapping); 2697 2698 /* 2699 *__split_huge_page() may need to trim off pages beyond EOF: 2700 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2701 * which cannot be nested inside the page tree lock. So note 2702 * end now: i_size itself may be changed at any moment, but 2703 * folio lock is good enough to serialize the trimming. 2704 */ 2705 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2706 if (shmem_mapping(mapping)) 2707 end = shmem_fallocend(mapping->host, end); 2708 } 2709 2710 /* 2711 * Racy check if we can split the page, before unmap_folio() will 2712 * split PMDs 2713 */ 2714 if (!can_split_folio(folio, &extra_pins)) { 2715 ret = -EBUSY; 2716 goto out_unlock; 2717 } 2718 2719 unmap_folio(folio); 2720 2721 /* block interrupt reentry in xa_lock and spinlock */ 2722 local_irq_disable(); 2723 if (mapping) { 2724 /* 2725 * Check if the folio is present in page cache. 2726 * We assume all tail are present too, if folio is there. 2727 */ 2728 xas_lock(&xas); 2729 xas_reset(&xas); 2730 if (xas_load(&xas) != folio) 2731 goto fail; 2732 } 2733 2734 /* Prevent deferred_split_scan() touching ->_refcount */ 2735 spin_lock(&ds_queue->split_queue_lock); 2736 if (folio_ref_freeze(folio, 1 + extra_pins)) { 2737 if (!list_empty(page_deferred_list(&folio->page))) { 2738 ds_queue->split_queue_len--; 2739 list_del(page_deferred_list(&folio->page)); 2740 } 2741 spin_unlock(&ds_queue->split_queue_lock); 2742 if (mapping) { 2743 int nr = folio_nr_pages(folio); 2744 2745 xas_split(&xas, folio, folio_order(folio)); 2746 if (folio_test_swapbacked(folio)) { 2747 __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, 2748 -nr); 2749 } else { 2750 __lruvec_stat_mod_folio(folio, NR_FILE_THPS, 2751 -nr); 2752 filemap_nr_thps_dec(mapping); 2753 } 2754 } 2755 2756 __split_huge_page(page, list, end); 2757 ret = 0; 2758 } else { 2759 spin_unlock(&ds_queue->split_queue_lock); 2760 fail: 2761 if (mapping) 2762 xas_unlock(&xas); 2763 local_irq_enable(); 2764 remap_page(folio, folio_nr_pages(folio)); 2765 ret = -EBUSY; 2766 } 2767 2768 out_unlock: 2769 if (anon_vma) { 2770 anon_vma_unlock_write(anon_vma); 2771 put_anon_vma(anon_vma); 2772 } 2773 if (mapping) 2774 i_mmap_unlock_read(mapping); 2775 out: 2776 xas_destroy(&xas); 2777 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2778 return ret; 2779 } 2780 2781 void free_transhuge_page(struct page *page) 2782 { 2783 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2784 unsigned long flags; 2785 2786 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2787 if (!list_empty(page_deferred_list(page))) { 2788 ds_queue->split_queue_len--; 2789 list_del(page_deferred_list(page)); 2790 } 2791 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2792 free_compound_page(page); 2793 } 2794 2795 void deferred_split_huge_page(struct page *page) 2796 { 2797 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2798 #ifdef CONFIG_MEMCG 2799 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 2800 #endif 2801 unsigned long flags; 2802 2803 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2804 2805 /* 2806 * The try_to_unmap() in page reclaim path might reach here too, 2807 * this may cause a race condition to corrupt deferred split queue. 2808 * And, if page reclaim is already handling the same page, it is 2809 * unnecessary to handle it again in shrinker. 2810 * 2811 * Check PageSwapCache to determine if the page is being 2812 * handled by page reclaim since THP swap would add the page into 2813 * swap cache before calling try_to_unmap(). 2814 */ 2815 if (PageSwapCache(page)) 2816 return; 2817 2818 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2819 if (list_empty(page_deferred_list(page))) { 2820 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2821 list_add_tail(page_deferred_list(page), &ds_queue->split_queue); 2822 ds_queue->split_queue_len++; 2823 #ifdef CONFIG_MEMCG 2824 if (memcg) 2825 set_shrinker_bit(memcg, page_to_nid(page), 2826 deferred_split_shrinker.id); 2827 #endif 2828 } 2829 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2830 } 2831 2832 static unsigned long deferred_split_count(struct shrinker *shrink, 2833 struct shrink_control *sc) 2834 { 2835 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2836 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2837 2838 #ifdef CONFIG_MEMCG 2839 if (sc->memcg) 2840 ds_queue = &sc->memcg->deferred_split_queue; 2841 #endif 2842 return READ_ONCE(ds_queue->split_queue_len); 2843 } 2844 2845 static unsigned long deferred_split_scan(struct shrinker *shrink, 2846 struct shrink_control *sc) 2847 { 2848 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2849 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2850 unsigned long flags; 2851 LIST_HEAD(list), *pos, *next; 2852 struct page *page; 2853 int split = 0; 2854 2855 #ifdef CONFIG_MEMCG 2856 if (sc->memcg) 2857 ds_queue = &sc->memcg->deferred_split_queue; 2858 #endif 2859 2860 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2861 /* Take pin on all head pages to avoid freeing them under us */ 2862 list_for_each_safe(pos, next, &ds_queue->split_queue) { 2863 page = list_entry((void *)pos, struct page, deferred_list); 2864 page = compound_head(page); 2865 if (get_page_unless_zero(page)) { 2866 list_move(page_deferred_list(page), &list); 2867 } else { 2868 /* We lost race with put_compound_page() */ 2869 list_del_init(page_deferred_list(page)); 2870 ds_queue->split_queue_len--; 2871 } 2872 if (!--sc->nr_to_scan) 2873 break; 2874 } 2875 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2876 2877 list_for_each_safe(pos, next, &list) { 2878 page = list_entry((void *)pos, struct page, deferred_list); 2879 if (!trylock_page(page)) 2880 goto next; 2881 /* split_huge_page() removes page from list on success */ 2882 if (!split_huge_page(page)) 2883 split++; 2884 unlock_page(page); 2885 next: 2886 put_page(page); 2887 } 2888 2889 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2890 list_splice_tail(&list, &ds_queue->split_queue); 2891 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2892 2893 /* 2894 * Stop shrinker if we didn't split any page, but the queue is empty. 2895 * This can happen if pages were freed under us. 2896 */ 2897 if (!split && list_empty(&ds_queue->split_queue)) 2898 return SHRINK_STOP; 2899 return split; 2900 } 2901 2902 static struct shrinker deferred_split_shrinker = { 2903 .count_objects = deferred_split_count, 2904 .scan_objects = deferred_split_scan, 2905 .seeks = DEFAULT_SEEKS, 2906 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | 2907 SHRINKER_NONSLAB, 2908 }; 2909 2910 #ifdef CONFIG_DEBUG_FS 2911 static void split_huge_pages_all(void) 2912 { 2913 struct zone *zone; 2914 struct page *page; 2915 unsigned long pfn, max_zone_pfn; 2916 unsigned long total = 0, split = 0; 2917 2918 pr_debug("Split all THPs\n"); 2919 for_each_zone(zone) { 2920 if (!managed_zone(zone)) 2921 continue; 2922 max_zone_pfn = zone_end_pfn(zone); 2923 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2924 int nr_pages; 2925 2926 page = pfn_to_online_page(pfn); 2927 if (!page || !get_page_unless_zero(page)) 2928 continue; 2929 2930 if (zone != page_zone(page)) 2931 goto next; 2932 2933 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 2934 goto next; 2935 2936 total++; 2937 lock_page(page); 2938 nr_pages = thp_nr_pages(page); 2939 if (!split_huge_page(page)) 2940 split++; 2941 pfn += nr_pages - 1; 2942 unlock_page(page); 2943 next: 2944 put_page(page); 2945 cond_resched(); 2946 } 2947 } 2948 2949 pr_debug("%lu of %lu THP split\n", split, total); 2950 } 2951 2952 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) 2953 { 2954 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || 2955 is_vm_hugetlb_page(vma); 2956 } 2957 2958 static int split_huge_pages_pid(int pid, unsigned long vaddr_start, 2959 unsigned long vaddr_end) 2960 { 2961 int ret = 0; 2962 struct task_struct *task; 2963 struct mm_struct *mm; 2964 unsigned long total = 0, split = 0; 2965 unsigned long addr; 2966 2967 vaddr_start &= PAGE_MASK; 2968 vaddr_end &= PAGE_MASK; 2969 2970 /* Find the task_struct from pid */ 2971 rcu_read_lock(); 2972 task = find_task_by_vpid(pid); 2973 if (!task) { 2974 rcu_read_unlock(); 2975 ret = -ESRCH; 2976 goto out; 2977 } 2978 get_task_struct(task); 2979 rcu_read_unlock(); 2980 2981 /* Find the mm_struct */ 2982 mm = get_task_mm(task); 2983 put_task_struct(task); 2984 2985 if (!mm) { 2986 ret = -EINVAL; 2987 goto out; 2988 } 2989 2990 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n", 2991 pid, vaddr_start, vaddr_end); 2992 2993 mmap_read_lock(mm); 2994 /* 2995 * always increase addr by PAGE_SIZE, since we could have a PTE page 2996 * table filled with PTE-mapped THPs, each of which is distinct. 2997 */ 2998 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { 2999 struct vm_area_struct *vma = vma_lookup(mm, addr); 3000 struct page *page; 3001 3002 if (!vma) 3003 break; 3004 3005 /* skip special VMA and hugetlb VMA */ 3006 if (vma_not_suitable_for_thp_split(vma)) { 3007 addr = vma->vm_end; 3008 continue; 3009 } 3010 3011 /* FOLL_DUMP to ignore special (like zero) pages */ 3012 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); 3013 3014 if (IS_ERR_OR_NULL(page)) 3015 continue; 3016 3017 if (!is_transparent_hugepage(page)) 3018 goto next; 3019 3020 total++; 3021 if (!can_split_folio(page_folio(page), NULL)) 3022 goto next; 3023 3024 if (!trylock_page(page)) 3025 goto next; 3026 3027 if (!split_huge_page(page)) 3028 split++; 3029 3030 unlock_page(page); 3031 next: 3032 put_page(page); 3033 cond_resched(); 3034 } 3035 mmap_read_unlock(mm); 3036 mmput(mm); 3037 3038 pr_debug("%lu of %lu THP split\n", split, total); 3039 3040 out: 3041 return ret; 3042 } 3043 3044 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, 3045 pgoff_t off_end) 3046 { 3047 struct filename *file; 3048 struct file *candidate; 3049 struct address_space *mapping; 3050 int ret = -EINVAL; 3051 pgoff_t index; 3052 int nr_pages = 1; 3053 unsigned long total = 0, split = 0; 3054 3055 file = getname_kernel(file_path); 3056 if (IS_ERR(file)) 3057 return ret; 3058 3059 candidate = file_open_name(file, O_RDONLY, 0); 3060 if (IS_ERR(candidate)) 3061 goto out; 3062 3063 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", 3064 file_path, off_start, off_end); 3065 3066 mapping = candidate->f_mapping; 3067 3068 for (index = off_start; index < off_end; index += nr_pages) { 3069 struct page *fpage = pagecache_get_page(mapping, index, 3070 FGP_ENTRY | FGP_HEAD, 0); 3071 3072 nr_pages = 1; 3073 if (xa_is_value(fpage) || !fpage) 3074 continue; 3075 3076 if (!is_transparent_hugepage(fpage)) 3077 goto next; 3078 3079 total++; 3080 nr_pages = thp_nr_pages(fpage); 3081 3082 if (!trylock_page(fpage)) 3083 goto next; 3084 3085 if (!split_huge_page(fpage)) 3086 split++; 3087 3088 unlock_page(fpage); 3089 next: 3090 put_page(fpage); 3091 cond_resched(); 3092 } 3093 3094 filp_close(candidate, NULL); 3095 ret = 0; 3096 3097 pr_debug("%lu of %lu file-backed THP split\n", split, total); 3098 out: 3099 putname(file); 3100 return ret; 3101 } 3102 3103 #define MAX_INPUT_BUF_SZ 255 3104 3105 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, 3106 size_t count, loff_t *ppops) 3107 { 3108 static DEFINE_MUTEX(split_debug_mutex); 3109 ssize_t ret; 3110 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */ 3111 char input_buf[MAX_INPUT_BUF_SZ]; 3112 int pid; 3113 unsigned long vaddr_start, vaddr_end; 3114 3115 ret = mutex_lock_interruptible(&split_debug_mutex); 3116 if (ret) 3117 return ret; 3118 3119 ret = -EFAULT; 3120 3121 memset(input_buf, 0, MAX_INPUT_BUF_SZ); 3122 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) 3123 goto out; 3124 3125 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; 3126 3127 if (input_buf[0] == '/') { 3128 char *tok; 3129 char *buf = input_buf; 3130 char file_path[MAX_INPUT_BUF_SZ]; 3131 pgoff_t off_start = 0, off_end = 0; 3132 size_t input_len = strlen(input_buf); 3133 3134 tok = strsep(&buf, ","); 3135 if (tok) { 3136 strcpy(file_path, tok); 3137 } else { 3138 ret = -EINVAL; 3139 goto out; 3140 } 3141 3142 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end); 3143 if (ret != 2) { 3144 ret = -EINVAL; 3145 goto out; 3146 } 3147 ret = split_huge_pages_in_file(file_path, off_start, off_end); 3148 if (!ret) 3149 ret = input_len; 3150 3151 goto out; 3152 } 3153 3154 ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end); 3155 if (ret == 1 && pid == 1) { 3156 split_huge_pages_all(); 3157 ret = strlen(input_buf); 3158 goto out; 3159 } else if (ret != 3) { 3160 ret = -EINVAL; 3161 goto out; 3162 } 3163 3164 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end); 3165 if (!ret) 3166 ret = strlen(input_buf); 3167 out: 3168 mutex_unlock(&split_debug_mutex); 3169 return ret; 3170 3171 } 3172 3173 static const struct file_operations split_huge_pages_fops = { 3174 .owner = THIS_MODULE, 3175 .write = split_huge_pages_write, 3176 .llseek = no_llseek, 3177 }; 3178 3179 static int __init split_huge_pages_debugfs(void) 3180 { 3181 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 3182 &split_huge_pages_fops); 3183 return 0; 3184 } 3185 late_initcall(split_huge_pages_debugfs); 3186 #endif 3187 3188 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 3189 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 3190 struct page *page) 3191 { 3192 struct vm_area_struct *vma = pvmw->vma; 3193 struct mm_struct *mm = vma->vm_mm; 3194 unsigned long address = pvmw->address; 3195 bool anon_exclusive; 3196 pmd_t pmdval; 3197 swp_entry_t entry; 3198 pmd_t pmdswp; 3199 3200 if (!(pvmw->pmd && !pvmw->pte)) 3201 return 0; 3202 3203 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 3204 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 3205 3206 /* See page_try_share_anon_rmap(): invalidate PMD first. */ 3207 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 3208 if (anon_exclusive && page_try_share_anon_rmap(page)) { 3209 set_pmd_at(mm, address, pvmw->pmd, pmdval); 3210 return -EBUSY; 3211 } 3212 3213 if (pmd_dirty(pmdval)) 3214 set_page_dirty(page); 3215 if (pmd_write(pmdval)) 3216 entry = make_writable_migration_entry(page_to_pfn(page)); 3217 else if (anon_exclusive) 3218 entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); 3219 else 3220 entry = make_readable_migration_entry(page_to_pfn(page)); 3221 if (pmd_young(pmdval)) 3222 entry = make_migration_entry_young(entry); 3223 if (pmd_dirty(pmdval)) 3224 entry = make_migration_entry_dirty(entry); 3225 pmdswp = swp_entry_to_pmd(entry); 3226 if (pmd_soft_dirty(pmdval)) 3227 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3228 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3229 page_remove_rmap(page, vma, true); 3230 put_page(page); 3231 trace_set_migration_pmd(address, pmd_val(pmdswp)); 3232 3233 return 0; 3234 } 3235 3236 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3237 { 3238 struct vm_area_struct *vma = pvmw->vma; 3239 struct mm_struct *mm = vma->vm_mm; 3240 unsigned long address = pvmw->address; 3241 unsigned long haddr = address & HPAGE_PMD_MASK; 3242 pmd_t pmde; 3243 swp_entry_t entry; 3244 3245 if (!(pvmw->pmd && !pvmw->pte)) 3246 return; 3247 3248 entry = pmd_to_swp_entry(*pvmw->pmd); 3249 get_page(new); 3250 pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot)); 3251 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3252 pmde = pmd_mksoft_dirty(pmde); 3253 if (is_writable_migration_entry(entry)) 3254 pmde = maybe_pmd_mkwrite(pmde, vma); 3255 if (pmd_swp_uffd_wp(*pvmw->pmd)) 3256 pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde)); 3257 if (!is_migration_entry_young(entry)) 3258 pmde = pmd_mkold(pmde); 3259 /* NOTE: this may contain setting soft-dirty on some archs */ 3260 if (PageDirty(new) && is_migration_entry_dirty(entry)) 3261 pmde = pmd_mkdirty(pmde); 3262 3263 if (PageAnon(new)) { 3264 rmap_t rmap_flags = RMAP_COMPOUND; 3265 3266 if (!is_readable_migration_entry(entry)) 3267 rmap_flags |= RMAP_EXCLUSIVE; 3268 3269 page_add_anon_rmap(new, vma, haddr, rmap_flags); 3270 } else { 3271 page_add_file_rmap(new, vma, true); 3272 } 3273 VM_BUG_ON(pmd_write(pmde) && PageAnon(new) && !PageAnonExclusive(new)); 3274 set_pmd_at(mm, haddr, pvmw->pmd, pmde); 3275 3276 /* No need to invalidate - it was non-present before */ 3277 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3278 trace_remove_migration_pmd(address, pmd_val(pmde)); 3279 } 3280 #endif 3281