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); 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 count_vm_event(THP_ZERO_PAGE_ALLOC); 167 preempt_disable(); 168 if (cmpxchg(&huge_zero_page, NULL, zero_page)) { 169 preempt_enable(); 170 __free_pages(zero_page, compound_order(zero_page)); 171 goto retry; 172 } 173 WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page)); 174 175 /* We take additional reference here. It will be put back by shrinker */ 176 atomic_set(&huge_zero_refcount, 2); 177 preempt_enable(); 178 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 page *page; 1309 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1310 pmd_t orig_pmd = vmf->orig_pmd; 1311 1312 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1313 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1314 1315 VM_BUG_ON(unshare && (vmf->flags & FAULT_FLAG_WRITE)); 1316 VM_BUG_ON(!unshare && !(vmf->flags & FAULT_FLAG_WRITE)); 1317 1318 if (is_huge_zero_pmd(orig_pmd)) 1319 goto fallback; 1320 1321 spin_lock(vmf->ptl); 1322 1323 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1324 spin_unlock(vmf->ptl); 1325 return 0; 1326 } 1327 1328 page = pmd_page(orig_pmd); 1329 VM_BUG_ON_PAGE(!PageHead(page), page); 1330 1331 /* Early check when only holding the PT lock. */ 1332 if (PageAnonExclusive(page)) 1333 goto reuse; 1334 1335 if (!trylock_page(page)) { 1336 get_page(page); 1337 spin_unlock(vmf->ptl); 1338 lock_page(page); 1339 spin_lock(vmf->ptl); 1340 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1341 spin_unlock(vmf->ptl); 1342 unlock_page(page); 1343 put_page(page); 1344 return 0; 1345 } 1346 put_page(page); 1347 } 1348 1349 /* Recheck after temporarily dropping the PT lock. */ 1350 if (PageAnonExclusive(page)) { 1351 unlock_page(page); 1352 goto reuse; 1353 } 1354 1355 /* 1356 * See do_wp_page(): we can only reuse the page exclusively if there are 1357 * no additional references. Note that we always drain the LRU 1358 * pagevecs immediately after adding a THP. 1359 */ 1360 if (page_count(page) > 1 + PageSwapCache(page) * thp_nr_pages(page)) 1361 goto unlock_fallback; 1362 if (PageSwapCache(page)) 1363 try_to_free_swap(page); 1364 if (page_count(page) == 1) { 1365 pmd_t entry; 1366 1367 page_move_anon_rmap(page, vma); 1368 unlock_page(page); 1369 reuse: 1370 if (unlikely(unshare)) { 1371 spin_unlock(vmf->ptl); 1372 return 0; 1373 } 1374 entry = pmd_mkyoung(orig_pmd); 1375 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1376 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1377 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1378 spin_unlock(vmf->ptl); 1379 return VM_FAULT_WRITE; 1380 } 1381 1382 unlock_fallback: 1383 unlock_page(page); 1384 spin_unlock(vmf->ptl); 1385 fallback: 1386 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1387 return VM_FAULT_FALLBACK; 1388 } 1389 1390 /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */ 1391 static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page, 1392 struct vm_area_struct *vma, 1393 unsigned int flags) 1394 { 1395 /* If the pmd is writable, we can write to the page. */ 1396 if (pmd_write(pmd)) 1397 return true; 1398 1399 /* Maybe FOLL_FORCE is set to override it? */ 1400 if (!(flags & FOLL_FORCE)) 1401 return false; 1402 1403 /* But FOLL_FORCE has no effect on shared mappings */ 1404 if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED)) 1405 return false; 1406 1407 /* ... or read-only private ones */ 1408 if (!(vma->vm_flags & VM_MAYWRITE)) 1409 return false; 1410 1411 /* ... or already writable ones that just need to take a write fault */ 1412 if (vma->vm_flags & VM_WRITE) 1413 return false; 1414 1415 /* 1416 * See can_change_pte_writable(): we broke COW and could map the page 1417 * writable if we have an exclusive anonymous page ... 1418 */ 1419 if (!page || !PageAnon(page) || !PageAnonExclusive(page)) 1420 return false; 1421 1422 /* ... and a write-fault isn't required for other reasons. */ 1423 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) 1424 return false; 1425 return !userfaultfd_huge_pmd_wp(vma, pmd); 1426 } 1427 1428 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1429 unsigned long addr, 1430 pmd_t *pmd, 1431 unsigned int flags) 1432 { 1433 struct mm_struct *mm = vma->vm_mm; 1434 struct page *page; 1435 1436 assert_spin_locked(pmd_lockptr(mm, pmd)); 1437 1438 page = pmd_page(*pmd); 1439 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1440 1441 if ((flags & FOLL_WRITE) && 1442 !can_follow_write_pmd(*pmd, page, vma, flags)) 1443 return NULL; 1444 1445 /* Avoid dumping huge zero page */ 1446 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1447 return ERR_PTR(-EFAULT); 1448 1449 /* Full NUMA hinting faults to serialise migration in fault paths */ 1450 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) 1451 return NULL; 1452 1453 if (!pmd_write(*pmd) && gup_must_unshare(flags, page)) 1454 return ERR_PTR(-EMLINK); 1455 1456 VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) && 1457 !PageAnonExclusive(page), page); 1458 1459 if (!try_grab_page(page, flags)) 1460 return ERR_PTR(-ENOMEM); 1461 1462 if (flags & FOLL_TOUCH) 1463 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1464 1465 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1466 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1467 1468 return page; 1469 } 1470 1471 /* NUMA hinting page fault entry point for trans huge pmds */ 1472 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) 1473 { 1474 struct vm_area_struct *vma = vmf->vma; 1475 pmd_t oldpmd = vmf->orig_pmd; 1476 pmd_t pmd; 1477 struct page *page; 1478 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1479 int page_nid = NUMA_NO_NODE; 1480 int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK); 1481 bool migrated = false; 1482 bool was_writable = pmd_savedwrite(oldpmd); 1483 int flags = 0; 1484 1485 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1486 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1487 spin_unlock(vmf->ptl); 1488 goto out; 1489 } 1490 1491 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1492 page = vm_normal_page_pmd(vma, haddr, pmd); 1493 if (!page) 1494 goto out_map; 1495 1496 /* See similar comment in do_numa_page for explanation */ 1497 if (!was_writable) 1498 flags |= TNF_NO_GROUP; 1499 1500 page_nid = page_to_nid(page); 1501 /* 1502 * For memory tiering mode, cpupid of slow memory page is used 1503 * to record page access time. So use default value. 1504 */ 1505 if (node_is_toptier(page_nid)) 1506 last_cpupid = page_cpupid_last(page); 1507 target_nid = numa_migrate_prep(page, vma, haddr, page_nid, 1508 &flags); 1509 1510 if (target_nid == NUMA_NO_NODE) { 1511 put_page(page); 1512 goto out_map; 1513 } 1514 1515 spin_unlock(vmf->ptl); 1516 1517 migrated = migrate_misplaced_page(page, vma, target_nid); 1518 if (migrated) { 1519 flags |= TNF_MIGRATED; 1520 page_nid = target_nid; 1521 } else { 1522 flags |= TNF_MIGRATE_FAIL; 1523 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1524 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1525 spin_unlock(vmf->ptl); 1526 goto out; 1527 } 1528 goto out_map; 1529 } 1530 1531 out: 1532 if (page_nid != NUMA_NO_NODE) 1533 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1534 flags); 1535 1536 return 0; 1537 1538 out_map: 1539 /* Restore the PMD */ 1540 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1541 pmd = pmd_mkyoung(pmd); 1542 if (was_writable) 1543 pmd = pmd_mkwrite(pmd); 1544 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1545 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1546 spin_unlock(vmf->ptl); 1547 goto out; 1548 } 1549 1550 /* 1551 * Return true if we do MADV_FREE successfully on entire pmd page. 1552 * Otherwise, return false. 1553 */ 1554 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1555 pmd_t *pmd, unsigned long addr, unsigned long next) 1556 { 1557 spinlock_t *ptl; 1558 pmd_t orig_pmd; 1559 struct page *page; 1560 struct mm_struct *mm = tlb->mm; 1561 bool ret = false; 1562 1563 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1564 1565 ptl = pmd_trans_huge_lock(pmd, vma); 1566 if (!ptl) 1567 goto out_unlocked; 1568 1569 orig_pmd = *pmd; 1570 if (is_huge_zero_pmd(orig_pmd)) 1571 goto out; 1572 1573 if (unlikely(!pmd_present(orig_pmd))) { 1574 VM_BUG_ON(thp_migration_supported() && 1575 !is_pmd_migration_entry(orig_pmd)); 1576 goto out; 1577 } 1578 1579 page = pmd_page(orig_pmd); 1580 /* 1581 * If other processes are mapping this page, we couldn't discard 1582 * the page unless they all do MADV_FREE so let's skip the page. 1583 */ 1584 if (total_mapcount(page) != 1) 1585 goto out; 1586 1587 if (!trylock_page(page)) 1588 goto out; 1589 1590 /* 1591 * If user want to discard part-pages of THP, split it so MADV_FREE 1592 * will deactivate only them. 1593 */ 1594 if (next - addr != HPAGE_PMD_SIZE) { 1595 get_page(page); 1596 spin_unlock(ptl); 1597 split_huge_page(page); 1598 unlock_page(page); 1599 put_page(page); 1600 goto out_unlocked; 1601 } 1602 1603 if (PageDirty(page)) 1604 ClearPageDirty(page); 1605 unlock_page(page); 1606 1607 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1608 pmdp_invalidate(vma, addr, pmd); 1609 orig_pmd = pmd_mkold(orig_pmd); 1610 orig_pmd = pmd_mkclean(orig_pmd); 1611 1612 set_pmd_at(mm, addr, pmd, orig_pmd); 1613 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1614 } 1615 1616 mark_page_lazyfree(page); 1617 ret = true; 1618 out: 1619 spin_unlock(ptl); 1620 out_unlocked: 1621 return ret; 1622 } 1623 1624 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1625 { 1626 pgtable_t pgtable; 1627 1628 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1629 pte_free(mm, pgtable); 1630 mm_dec_nr_ptes(mm); 1631 } 1632 1633 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1634 pmd_t *pmd, unsigned long addr) 1635 { 1636 pmd_t orig_pmd; 1637 spinlock_t *ptl; 1638 1639 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1640 1641 ptl = __pmd_trans_huge_lock(pmd, vma); 1642 if (!ptl) 1643 return 0; 1644 /* 1645 * For architectures like ppc64 we look at deposited pgtable 1646 * when calling pmdp_huge_get_and_clear. So do the 1647 * pgtable_trans_huge_withdraw after finishing pmdp related 1648 * operations. 1649 */ 1650 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1651 tlb->fullmm); 1652 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1653 if (vma_is_special_huge(vma)) { 1654 if (arch_needs_pgtable_deposit()) 1655 zap_deposited_table(tlb->mm, pmd); 1656 spin_unlock(ptl); 1657 } else if (is_huge_zero_pmd(orig_pmd)) { 1658 zap_deposited_table(tlb->mm, pmd); 1659 spin_unlock(ptl); 1660 } else { 1661 struct page *page = NULL; 1662 int flush_needed = 1; 1663 1664 if (pmd_present(orig_pmd)) { 1665 page = pmd_page(orig_pmd); 1666 page_remove_rmap(page, vma, true); 1667 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1668 VM_BUG_ON_PAGE(!PageHead(page), page); 1669 } else if (thp_migration_supported()) { 1670 swp_entry_t entry; 1671 1672 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1673 entry = pmd_to_swp_entry(orig_pmd); 1674 page = pfn_swap_entry_to_page(entry); 1675 flush_needed = 0; 1676 } else 1677 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1678 1679 if (PageAnon(page)) { 1680 zap_deposited_table(tlb->mm, pmd); 1681 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1682 } else { 1683 if (arch_needs_pgtable_deposit()) 1684 zap_deposited_table(tlb->mm, pmd); 1685 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1686 } 1687 1688 spin_unlock(ptl); 1689 if (flush_needed) 1690 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1691 } 1692 return 1; 1693 } 1694 1695 #ifndef pmd_move_must_withdraw 1696 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1697 spinlock_t *old_pmd_ptl, 1698 struct vm_area_struct *vma) 1699 { 1700 /* 1701 * With split pmd lock we also need to move preallocated 1702 * PTE page table if new_pmd is on different PMD page table. 1703 * 1704 * We also don't deposit and withdraw tables for file pages. 1705 */ 1706 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1707 } 1708 #endif 1709 1710 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1711 { 1712 #ifdef CONFIG_MEM_SOFT_DIRTY 1713 if (unlikely(is_pmd_migration_entry(pmd))) 1714 pmd = pmd_swp_mksoft_dirty(pmd); 1715 else if (pmd_present(pmd)) 1716 pmd = pmd_mksoft_dirty(pmd); 1717 #endif 1718 return pmd; 1719 } 1720 1721 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1722 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1723 { 1724 spinlock_t *old_ptl, *new_ptl; 1725 pmd_t pmd; 1726 struct mm_struct *mm = vma->vm_mm; 1727 bool force_flush = false; 1728 1729 /* 1730 * The destination pmd shouldn't be established, free_pgtables() 1731 * should have release it. 1732 */ 1733 if (WARN_ON(!pmd_none(*new_pmd))) { 1734 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1735 return false; 1736 } 1737 1738 /* 1739 * We don't have to worry about the ordering of src and dst 1740 * ptlocks because exclusive mmap_lock prevents deadlock. 1741 */ 1742 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1743 if (old_ptl) { 1744 new_ptl = pmd_lockptr(mm, new_pmd); 1745 if (new_ptl != old_ptl) 1746 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1747 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1748 if (pmd_present(pmd)) 1749 force_flush = true; 1750 VM_BUG_ON(!pmd_none(*new_pmd)); 1751 1752 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1753 pgtable_t pgtable; 1754 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1755 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1756 } 1757 pmd = move_soft_dirty_pmd(pmd); 1758 set_pmd_at(mm, new_addr, new_pmd, pmd); 1759 if (force_flush) 1760 flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1761 if (new_ptl != old_ptl) 1762 spin_unlock(new_ptl); 1763 spin_unlock(old_ptl); 1764 return true; 1765 } 1766 return false; 1767 } 1768 1769 /* 1770 * Returns 1771 * - 0 if PMD could not be locked 1772 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary 1773 * or if prot_numa but THP migration is not supported 1774 * - HPAGE_PMD_NR if protections changed and TLB flush necessary 1775 */ 1776 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1777 pmd_t *pmd, unsigned long addr, pgprot_t newprot, 1778 unsigned long cp_flags) 1779 { 1780 struct mm_struct *mm = vma->vm_mm; 1781 spinlock_t *ptl; 1782 pmd_t oldpmd, entry; 1783 bool preserve_write; 1784 int ret; 1785 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1786 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1787 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1788 1789 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1790 1791 if (prot_numa && !thp_migration_supported()) 1792 return 1; 1793 1794 ptl = __pmd_trans_huge_lock(pmd, vma); 1795 if (!ptl) 1796 return 0; 1797 1798 preserve_write = prot_numa && pmd_write(*pmd); 1799 ret = 1; 1800 1801 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1802 if (is_swap_pmd(*pmd)) { 1803 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1804 struct page *page = pfn_swap_entry_to_page(entry); 1805 1806 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1807 if (is_writable_migration_entry(entry)) { 1808 pmd_t newpmd; 1809 /* 1810 * A protection check is difficult so 1811 * just be safe and disable write 1812 */ 1813 if (PageAnon(page)) 1814 entry = make_readable_exclusive_migration_entry(swp_offset(entry)); 1815 else 1816 entry = make_readable_migration_entry(swp_offset(entry)); 1817 newpmd = swp_entry_to_pmd(entry); 1818 if (pmd_swp_soft_dirty(*pmd)) 1819 newpmd = pmd_swp_mksoft_dirty(newpmd); 1820 if (pmd_swp_uffd_wp(*pmd)) 1821 newpmd = pmd_swp_mkuffd_wp(newpmd); 1822 set_pmd_at(mm, addr, pmd, newpmd); 1823 } 1824 goto unlock; 1825 } 1826 #endif 1827 1828 if (prot_numa) { 1829 struct page *page; 1830 bool toptier; 1831 /* 1832 * Avoid trapping faults against the zero page. The read-only 1833 * data is likely to be read-cached on the local CPU and 1834 * local/remote hits to the zero page are not interesting. 1835 */ 1836 if (is_huge_zero_pmd(*pmd)) 1837 goto unlock; 1838 1839 if (pmd_protnone(*pmd)) 1840 goto unlock; 1841 1842 page = pmd_page(*pmd); 1843 toptier = node_is_toptier(page_to_nid(page)); 1844 /* 1845 * Skip scanning top tier node if normal numa 1846 * balancing is disabled 1847 */ 1848 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 1849 toptier) 1850 goto unlock; 1851 1852 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING && 1853 !toptier) 1854 xchg_page_access_time(page, jiffies_to_msecs(jiffies)); 1855 } 1856 /* 1857 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 1858 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1859 * which is also under mmap_read_lock(mm): 1860 * 1861 * CPU0: CPU1: 1862 * change_huge_pmd(prot_numa=1) 1863 * pmdp_huge_get_and_clear_notify() 1864 * madvise_dontneed() 1865 * zap_pmd_range() 1866 * pmd_trans_huge(*pmd) == 0 (without ptl) 1867 * // skip the pmd 1868 * set_pmd_at(); 1869 * // pmd is re-established 1870 * 1871 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1872 * which may break userspace. 1873 * 1874 * pmdp_invalidate_ad() is required to make sure we don't miss 1875 * dirty/young flags set by hardware. 1876 */ 1877 oldpmd = pmdp_invalidate_ad(vma, addr, pmd); 1878 1879 entry = pmd_modify(oldpmd, newprot); 1880 if (preserve_write) 1881 entry = pmd_mk_savedwrite(entry); 1882 if (uffd_wp) { 1883 entry = pmd_wrprotect(entry); 1884 entry = pmd_mkuffd_wp(entry); 1885 } else if (uffd_wp_resolve) { 1886 /* 1887 * Leave the write bit to be handled by PF interrupt 1888 * handler, then things like COW could be properly 1889 * handled. 1890 */ 1891 entry = pmd_clear_uffd_wp(entry); 1892 } 1893 ret = HPAGE_PMD_NR; 1894 set_pmd_at(mm, addr, pmd, entry); 1895 1896 if (huge_pmd_needs_flush(oldpmd, entry)) 1897 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); 1898 1899 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); 1900 unlock: 1901 spin_unlock(ptl); 1902 return ret; 1903 } 1904 1905 /* 1906 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1907 * 1908 * Note that if it returns page table lock pointer, this routine returns without 1909 * unlocking page table lock. So callers must unlock it. 1910 */ 1911 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1912 { 1913 spinlock_t *ptl; 1914 ptl = pmd_lock(vma->vm_mm, pmd); 1915 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 1916 pmd_devmap(*pmd))) 1917 return ptl; 1918 spin_unlock(ptl); 1919 return NULL; 1920 } 1921 1922 /* 1923 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. 1924 * 1925 * Note that if it returns page table lock pointer, this routine returns without 1926 * unlocking page table lock. So callers must unlock it. 1927 */ 1928 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 1929 { 1930 spinlock_t *ptl; 1931 1932 ptl = pud_lock(vma->vm_mm, pud); 1933 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 1934 return ptl; 1935 spin_unlock(ptl); 1936 return NULL; 1937 } 1938 1939 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1940 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 1941 pud_t *pud, unsigned long addr) 1942 { 1943 spinlock_t *ptl; 1944 1945 ptl = __pud_trans_huge_lock(pud, vma); 1946 if (!ptl) 1947 return 0; 1948 1949 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 1950 tlb_remove_pud_tlb_entry(tlb, pud, addr); 1951 if (vma_is_special_huge(vma)) { 1952 spin_unlock(ptl); 1953 /* No zero page support yet */ 1954 } else { 1955 /* No support for anonymous PUD pages yet */ 1956 BUG(); 1957 } 1958 return 1; 1959 } 1960 1961 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 1962 unsigned long haddr) 1963 { 1964 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 1965 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 1966 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 1967 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 1968 1969 count_vm_event(THP_SPLIT_PUD); 1970 1971 pudp_huge_clear_flush_notify(vma, haddr, pud); 1972 } 1973 1974 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 1975 unsigned long address) 1976 { 1977 spinlock_t *ptl; 1978 struct mmu_notifier_range range; 1979 1980 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1981 address & HPAGE_PUD_MASK, 1982 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 1983 mmu_notifier_invalidate_range_start(&range); 1984 ptl = pud_lock(vma->vm_mm, pud); 1985 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 1986 goto out; 1987 __split_huge_pud_locked(vma, pud, range.start); 1988 1989 out: 1990 spin_unlock(ptl); 1991 /* 1992 * No need to double call mmu_notifier->invalidate_range() callback as 1993 * the above pudp_huge_clear_flush_notify() did already call it. 1994 */ 1995 mmu_notifier_invalidate_range_only_end(&range); 1996 } 1997 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1998 1999 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2000 unsigned long haddr, pmd_t *pmd) 2001 { 2002 struct mm_struct *mm = vma->vm_mm; 2003 pgtable_t pgtable; 2004 pmd_t _pmd; 2005 int i; 2006 2007 /* 2008 * Leave pmd empty until pte is filled note that it is fine to delay 2009 * notification until mmu_notifier_invalidate_range_end() as we are 2010 * replacing a zero pmd write protected page with a zero pte write 2011 * protected page. 2012 * 2013 * See Documentation/mm/mmu_notifier.rst 2014 */ 2015 pmdp_huge_clear_flush(vma, haddr, pmd); 2016 2017 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2018 pmd_populate(mm, &_pmd, pgtable); 2019 2020 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 2021 pte_t *pte, entry; 2022 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 2023 entry = pte_mkspecial(entry); 2024 pte = pte_offset_map(&_pmd, haddr); 2025 VM_BUG_ON(!pte_none(*pte)); 2026 set_pte_at(mm, haddr, pte, entry); 2027 pte_unmap(pte); 2028 } 2029 smp_wmb(); /* make pte visible before pmd */ 2030 pmd_populate(mm, pmd, pgtable); 2031 } 2032 2033 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2034 unsigned long haddr, bool freeze) 2035 { 2036 struct mm_struct *mm = vma->vm_mm; 2037 struct page *page; 2038 pgtable_t pgtable; 2039 pmd_t old_pmd, _pmd; 2040 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 2041 bool anon_exclusive = false, dirty = false; 2042 unsigned long addr; 2043 int i; 2044 2045 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2046 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2047 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2048 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2049 && !pmd_devmap(*pmd)); 2050 2051 count_vm_event(THP_SPLIT_PMD); 2052 2053 if (!vma_is_anonymous(vma)) { 2054 old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 2055 /* 2056 * We are going to unmap this huge page. So 2057 * just go ahead and zap it 2058 */ 2059 if (arch_needs_pgtable_deposit()) 2060 zap_deposited_table(mm, pmd); 2061 if (vma_is_special_huge(vma)) 2062 return; 2063 if (unlikely(is_pmd_migration_entry(old_pmd))) { 2064 swp_entry_t entry; 2065 2066 entry = pmd_to_swp_entry(old_pmd); 2067 page = pfn_swap_entry_to_page(entry); 2068 } else { 2069 page = pmd_page(old_pmd); 2070 if (!PageDirty(page) && pmd_dirty(old_pmd)) 2071 set_page_dirty(page); 2072 if (!PageReferenced(page) && pmd_young(old_pmd)) 2073 SetPageReferenced(page); 2074 page_remove_rmap(page, vma, true); 2075 put_page(page); 2076 } 2077 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2078 return; 2079 } 2080 2081 if (is_huge_zero_pmd(*pmd)) { 2082 /* 2083 * FIXME: Do we want to invalidate secondary mmu by calling 2084 * mmu_notifier_invalidate_range() see comments below inside 2085 * __split_huge_pmd() ? 2086 * 2087 * We are going from a zero huge page write protected to zero 2088 * small page also write protected so it does not seems useful 2089 * to invalidate secondary mmu at this time. 2090 */ 2091 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2092 } 2093 2094 /* 2095 * Up to this point the pmd is present and huge and userland has the 2096 * whole access to the hugepage during the split (which happens in 2097 * place). If we overwrite the pmd with the not-huge version pointing 2098 * to the pte here (which of course we could if all CPUs were bug 2099 * free), userland could trigger a small page size TLB miss on the 2100 * small sized TLB while the hugepage TLB entry is still established in 2101 * the huge TLB. Some CPU doesn't like that. 2102 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2103 * 383 on page 105. Intel should be safe but is also warns that it's 2104 * only safe if the permission and cache attributes of the two entries 2105 * loaded in the two TLB is identical (which should be the case here). 2106 * But it is generally safer to never allow small and huge TLB entries 2107 * for the same virtual address to be loaded simultaneously. So instead 2108 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2109 * current pmd notpresent (atomically because here the pmd_trans_huge 2110 * must remain set at all times on the pmd until the split is complete 2111 * for this pmd), then we flush the SMP TLB and finally we write the 2112 * non-huge version of the pmd entry with pmd_populate. 2113 */ 2114 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2115 2116 pmd_migration = is_pmd_migration_entry(old_pmd); 2117 if (unlikely(pmd_migration)) { 2118 swp_entry_t entry; 2119 2120 entry = pmd_to_swp_entry(old_pmd); 2121 page = pfn_swap_entry_to_page(entry); 2122 write = is_writable_migration_entry(entry); 2123 if (PageAnon(page)) 2124 anon_exclusive = is_readable_exclusive_migration_entry(entry); 2125 young = is_migration_entry_young(entry); 2126 dirty = is_migration_entry_dirty(entry); 2127 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2128 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2129 } else { 2130 page = pmd_page(old_pmd); 2131 if (pmd_dirty(old_pmd)) { 2132 dirty = true; 2133 SetPageDirty(page); 2134 } 2135 write = pmd_write(old_pmd); 2136 young = pmd_young(old_pmd); 2137 soft_dirty = pmd_soft_dirty(old_pmd); 2138 uffd_wp = pmd_uffd_wp(old_pmd); 2139 2140 VM_BUG_ON_PAGE(!page_count(page), page); 2141 page_ref_add(page, HPAGE_PMD_NR - 1); 2142 2143 /* 2144 * Without "freeze", we'll simply split the PMD, propagating the 2145 * PageAnonExclusive() flag for each PTE by setting it for 2146 * each subpage -- no need to (temporarily) clear. 2147 * 2148 * With "freeze" we want to replace mapped pages by 2149 * migration entries right away. This is only possible if we 2150 * managed to clear PageAnonExclusive() -- see 2151 * set_pmd_migration_entry(). 2152 * 2153 * In case we cannot clear PageAnonExclusive(), split the PMD 2154 * only and let try_to_migrate_one() fail later. 2155 * 2156 * See page_try_share_anon_rmap(): invalidate PMD first. 2157 */ 2158 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 2159 if (freeze && anon_exclusive && page_try_share_anon_rmap(page)) 2160 freeze = false; 2161 } 2162 2163 /* 2164 * Withdraw the table only after we mark the pmd entry invalid. 2165 * This's critical for some architectures (Power). 2166 */ 2167 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2168 pmd_populate(mm, &_pmd, pgtable); 2169 2170 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2171 pte_t entry, *pte; 2172 /* 2173 * Note that NUMA hinting access restrictions are not 2174 * transferred to avoid any possibility of altering 2175 * permissions across VMAs. 2176 */ 2177 if (freeze || pmd_migration) { 2178 swp_entry_t swp_entry; 2179 if (write) 2180 swp_entry = make_writable_migration_entry( 2181 page_to_pfn(page + i)); 2182 else if (anon_exclusive) 2183 swp_entry = make_readable_exclusive_migration_entry( 2184 page_to_pfn(page + i)); 2185 else 2186 swp_entry = make_readable_migration_entry( 2187 page_to_pfn(page + i)); 2188 if (young) 2189 swp_entry = make_migration_entry_young(swp_entry); 2190 if (dirty) 2191 swp_entry = make_migration_entry_dirty(swp_entry); 2192 entry = swp_entry_to_pte(swp_entry); 2193 if (soft_dirty) 2194 entry = pte_swp_mksoft_dirty(entry); 2195 if (uffd_wp) 2196 entry = pte_swp_mkuffd_wp(entry); 2197 } else { 2198 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2199 entry = maybe_mkwrite(entry, vma); 2200 if (anon_exclusive) 2201 SetPageAnonExclusive(page + i); 2202 if (!write) 2203 entry = pte_wrprotect(entry); 2204 if (!young) 2205 entry = pte_mkold(entry); 2206 /* NOTE: this may set soft-dirty too on some archs */ 2207 if (dirty) 2208 entry = pte_mkdirty(entry); 2209 if (soft_dirty) 2210 entry = pte_mksoft_dirty(entry); 2211 if (uffd_wp) 2212 entry = pte_mkuffd_wp(entry); 2213 } 2214 pte = pte_offset_map(&_pmd, addr); 2215 BUG_ON(!pte_none(*pte)); 2216 set_pte_at(mm, addr, pte, entry); 2217 if (!pmd_migration) 2218 atomic_inc(&page[i]._mapcount); 2219 pte_unmap(pte); 2220 } 2221 2222 if (!pmd_migration) { 2223 /* 2224 * Set PG_double_map before dropping compound_mapcount to avoid 2225 * false-negative page_mapped(). 2226 */ 2227 if (compound_mapcount(page) > 1 && 2228 !TestSetPageDoubleMap(page)) { 2229 for (i = 0; i < HPAGE_PMD_NR; i++) 2230 atomic_inc(&page[i]._mapcount); 2231 } 2232 2233 lock_page_memcg(page); 2234 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { 2235 /* Last compound_mapcount is gone. */ 2236 __mod_lruvec_page_state(page, NR_ANON_THPS, 2237 -HPAGE_PMD_NR); 2238 if (TestClearPageDoubleMap(page)) { 2239 /* No need in mapcount reference anymore */ 2240 for (i = 0; i < HPAGE_PMD_NR; i++) 2241 atomic_dec(&page[i]._mapcount); 2242 } 2243 } 2244 unlock_page_memcg(page); 2245 2246 /* Above is effectively page_remove_rmap(page, vma, true) */ 2247 munlock_vma_page(page, vma, true); 2248 } 2249 2250 smp_wmb(); /* make pte visible before pmd */ 2251 pmd_populate(mm, pmd, pgtable); 2252 2253 if (freeze) { 2254 for (i = 0; i < HPAGE_PMD_NR; i++) { 2255 page_remove_rmap(page + i, vma, false); 2256 put_page(page + i); 2257 } 2258 } 2259 } 2260 2261 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2262 unsigned long address, bool freeze, struct folio *folio) 2263 { 2264 spinlock_t *ptl; 2265 struct mmu_notifier_range range; 2266 2267 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2268 address & HPAGE_PMD_MASK, 2269 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2270 mmu_notifier_invalidate_range_start(&range); 2271 ptl = pmd_lock(vma->vm_mm, pmd); 2272 2273 /* 2274 * If caller asks to setup a migration entry, we need a folio to check 2275 * pmd against. Otherwise we can end up replacing wrong folio. 2276 */ 2277 VM_BUG_ON(freeze && !folio); 2278 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); 2279 2280 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || 2281 is_pmd_migration_entry(*pmd)) { 2282 /* 2283 * It's safe to call pmd_page when folio is set because it's 2284 * guaranteed that pmd is present. 2285 */ 2286 if (folio && folio != page_folio(pmd_page(*pmd))) 2287 goto out; 2288 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2289 } 2290 2291 out: 2292 spin_unlock(ptl); 2293 /* 2294 * No need to double call mmu_notifier->invalidate_range() callback. 2295 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2296 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2297 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2298 * fault will trigger a flush_notify before pointing to a new page 2299 * (it is fine if the secondary mmu keeps pointing to the old zero 2300 * page in the meantime) 2301 * 3) Split a huge pmd into pte pointing to the same page. No need 2302 * to invalidate secondary tlb entry they are all still valid. 2303 * any further changes to individual pte will notify. So no need 2304 * to call mmu_notifier->invalidate_range() 2305 */ 2306 mmu_notifier_invalidate_range_only_end(&range); 2307 } 2308 2309 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2310 bool freeze, struct folio *folio) 2311 { 2312 pmd_t *pmd = mm_find_pmd(vma->vm_mm, address); 2313 2314 if (!pmd) 2315 return; 2316 2317 __split_huge_pmd(vma, pmd, address, freeze, folio); 2318 } 2319 2320 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) 2321 { 2322 /* 2323 * If the new address isn't hpage aligned and it could previously 2324 * contain an hugepage: check if we need to split an huge pmd. 2325 */ 2326 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && 2327 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), 2328 ALIGN(address, HPAGE_PMD_SIZE))) 2329 split_huge_pmd_address(vma, address, false, NULL); 2330 } 2331 2332 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2333 unsigned long start, 2334 unsigned long end, 2335 long adjust_next) 2336 { 2337 /* Check if we need to split start first. */ 2338 split_huge_pmd_if_needed(vma, start); 2339 2340 /* Check if we need to split end next. */ 2341 split_huge_pmd_if_needed(vma, end); 2342 2343 /* 2344 * If we're also updating the vma->vm_next->vm_start, 2345 * check if we need to split it. 2346 */ 2347 if (adjust_next > 0) { 2348 struct vm_area_struct *next = vma->vm_next; 2349 unsigned long nstart = next->vm_start; 2350 nstart += adjust_next; 2351 split_huge_pmd_if_needed(next, nstart); 2352 } 2353 } 2354 2355 static void unmap_page(struct page *page) 2356 { 2357 struct folio *folio = page_folio(page); 2358 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | 2359 TTU_SYNC; 2360 2361 VM_BUG_ON_PAGE(!PageHead(page), page); 2362 2363 /* 2364 * Anon pages need migration entries to preserve them, but file 2365 * pages can simply be left unmapped, then faulted back on demand. 2366 * If that is ever changed (perhaps for mlock), update remap_page(). 2367 */ 2368 if (folio_test_anon(folio)) 2369 try_to_migrate(folio, ttu_flags); 2370 else 2371 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); 2372 } 2373 2374 static void remap_page(struct folio *folio, unsigned long nr) 2375 { 2376 int i = 0; 2377 2378 /* If unmap_page() uses try_to_migrate() on file, remove this check */ 2379 if (!folio_test_anon(folio)) 2380 return; 2381 for (;;) { 2382 remove_migration_ptes(folio, folio, true); 2383 i += folio_nr_pages(folio); 2384 if (i >= nr) 2385 break; 2386 folio = folio_next(folio); 2387 } 2388 } 2389 2390 static void lru_add_page_tail(struct page *head, struct page *tail, 2391 struct lruvec *lruvec, struct list_head *list) 2392 { 2393 VM_BUG_ON_PAGE(!PageHead(head), head); 2394 VM_BUG_ON_PAGE(PageCompound(tail), head); 2395 VM_BUG_ON_PAGE(PageLRU(tail), head); 2396 lockdep_assert_held(&lruvec->lru_lock); 2397 2398 if (list) { 2399 /* page reclaim is reclaiming a huge page */ 2400 VM_WARN_ON(PageLRU(head)); 2401 get_page(tail); 2402 list_add_tail(&tail->lru, list); 2403 } else { 2404 /* head is still on lru (and we have it frozen) */ 2405 VM_WARN_ON(!PageLRU(head)); 2406 if (PageUnevictable(tail)) 2407 tail->mlock_count = 0; 2408 else 2409 list_add_tail(&tail->lru, &head->lru); 2410 SetPageLRU(tail); 2411 } 2412 } 2413 2414 static void __split_huge_page_tail(struct page *head, int tail, 2415 struct lruvec *lruvec, struct list_head *list) 2416 { 2417 struct page *page_tail = head + tail; 2418 2419 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2420 2421 /* 2422 * Clone page flags before unfreezing refcount. 2423 * 2424 * After successful get_page_unless_zero() might follow flags change, 2425 * for example lock_page() which set PG_waiters. 2426 * 2427 * Note that for mapped sub-pages of an anonymous THP, 2428 * PG_anon_exclusive has been cleared in unmap_page() and is stored in 2429 * the migration entry instead from where remap_page() will restore it. 2430 * We can still have PG_anon_exclusive set on effectively unmapped and 2431 * unreferenced sub-pages of an anonymous THP: we can simply drop 2432 * PG_anon_exclusive (-> PG_mappedtodisk) for these here. 2433 */ 2434 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2435 page_tail->flags |= (head->flags & 2436 ((1L << PG_referenced) | 2437 (1L << PG_swapbacked) | 2438 (1L << PG_swapcache) | 2439 (1L << PG_mlocked) | 2440 (1L << PG_uptodate) | 2441 (1L << PG_active) | 2442 (1L << PG_workingset) | 2443 (1L << PG_locked) | 2444 (1L << PG_unevictable) | 2445 #ifdef CONFIG_64BIT 2446 (1L << PG_arch_2) | 2447 #endif 2448 (1L << PG_dirty) | 2449 LRU_GEN_MASK | LRU_REFS_MASK)); 2450 2451 /* ->mapping in first tail page is compound_mapcount */ 2452 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2453 page_tail); 2454 page_tail->mapping = head->mapping; 2455 page_tail->index = head->index + tail; 2456 page_tail->private = 0; 2457 2458 /* Page flags must be visible before we make the page non-compound. */ 2459 smp_wmb(); 2460 2461 /* 2462 * Clear PageTail before unfreezing page refcount. 2463 * 2464 * After successful get_page_unless_zero() might follow put_page() 2465 * which needs correct compound_head(). 2466 */ 2467 clear_compound_head(page_tail); 2468 2469 /* Finally unfreeze refcount. Additional reference from page cache. */ 2470 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2471 PageSwapCache(head))); 2472 2473 if (page_is_young(head)) 2474 set_page_young(page_tail); 2475 if (page_is_idle(head)) 2476 set_page_idle(page_tail); 2477 2478 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2479 2480 /* 2481 * always add to the tail because some iterators expect new 2482 * pages to show after the currently processed elements - e.g. 2483 * migrate_pages 2484 */ 2485 lru_add_page_tail(head, page_tail, lruvec, list); 2486 } 2487 2488 static void __split_huge_page(struct page *page, struct list_head *list, 2489 pgoff_t end) 2490 { 2491 struct folio *folio = page_folio(page); 2492 struct page *head = &folio->page; 2493 struct lruvec *lruvec; 2494 struct address_space *swap_cache = NULL; 2495 unsigned long offset = 0; 2496 unsigned int nr = thp_nr_pages(head); 2497 int i; 2498 2499 /* complete memcg works before add pages to LRU */ 2500 split_page_memcg(head, nr); 2501 2502 if (PageAnon(head) && PageSwapCache(head)) { 2503 swp_entry_t entry = { .val = page_private(head) }; 2504 2505 offset = swp_offset(entry); 2506 swap_cache = swap_address_space(entry); 2507 xa_lock(&swap_cache->i_pages); 2508 } 2509 2510 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ 2511 lruvec = folio_lruvec_lock(folio); 2512 2513 ClearPageHasHWPoisoned(head); 2514 2515 for (i = nr - 1; i >= 1; i--) { 2516 __split_huge_page_tail(head, i, lruvec, list); 2517 /* Some pages can be beyond EOF: drop them from page cache */ 2518 if (head[i].index >= end) { 2519 struct folio *tail = page_folio(head + i); 2520 2521 if (shmem_mapping(head->mapping)) 2522 shmem_uncharge(head->mapping->host, 1); 2523 else if (folio_test_clear_dirty(tail)) 2524 folio_account_cleaned(tail, 2525 inode_to_wb(folio->mapping->host)); 2526 __filemap_remove_folio(tail, NULL); 2527 folio_put(tail); 2528 } else if (!PageAnon(page)) { 2529 __xa_store(&head->mapping->i_pages, head[i].index, 2530 head + i, 0); 2531 } else if (swap_cache) { 2532 __xa_store(&swap_cache->i_pages, offset + i, 2533 head + i, 0); 2534 } 2535 } 2536 2537 ClearPageCompound(head); 2538 unlock_page_lruvec(lruvec); 2539 /* Caller disabled irqs, so they are still disabled here */ 2540 2541 split_page_owner(head, nr); 2542 2543 /* See comment in __split_huge_page_tail() */ 2544 if (PageAnon(head)) { 2545 /* Additional pin to swap cache */ 2546 if (PageSwapCache(head)) { 2547 page_ref_add(head, 2); 2548 xa_unlock(&swap_cache->i_pages); 2549 } else { 2550 page_ref_inc(head); 2551 } 2552 } else { 2553 /* Additional pin to page cache */ 2554 page_ref_add(head, 2); 2555 xa_unlock(&head->mapping->i_pages); 2556 } 2557 local_irq_enable(); 2558 2559 remap_page(folio, nr); 2560 2561 if (PageSwapCache(head)) { 2562 swp_entry_t entry = { .val = page_private(head) }; 2563 2564 split_swap_cluster(entry); 2565 } 2566 2567 for (i = 0; i < nr; i++) { 2568 struct page *subpage = head + i; 2569 if (subpage == page) 2570 continue; 2571 unlock_page(subpage); 2572 2573 /* 2574 * Subpages may be freed if there wasn't any mapping 2575 * like if add_to_swap() is running on a lru page that 2576 * had its mapping zapped. And freeing these pages 2577 * requires taking the lru_lock so we do the put_page 2578 * of the tail pages after the split is complete. 2579 */ 2580 free_page_and_swap_cache(subpage); 2581 } 2582 } 2583 2584 /* Racy check whether the huge page can be split */ 2585 bool can_split_folio(struct folio *folio, int *pextra_pins) 2586 { 2587 int extra_pins; 2588 2589 /* Additional pins from page cache */ 2590 if (folio_test_anon(folio)) 2591 extra_pins = folio_test_swapcache(folio) ? 2592 folio_nr_pages(folio) : 0; 2593 else 2594 extra_pins = folio_nr_pages(folio); 2595 if (pextra_pins) 2596 *pextra_pins = extra_pins; 2597 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1; 2598 } 2599 2600 /* 2601 * This function splits huge page into normal pages. @page can point to any 2602 * subpage of huge page to split. Split doesn't change the position of @page. 2603 * 2604 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2605 * The huge page must be locked. 2606 * 2607 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2608 * 2609 * Both head page and tail pages will inherit mapping, flags, and so on from 2610 * the hugepage. 2611 * 2612 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2613 * they are not mapped. 2614 * 2615 * Returns 0 if the hugepage is split successfully. 2616 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2617 * us. 2618 */ 2619 int split_huge_page_to_list(struct page *page, struct list_head *list) 2620 { 2621 struct folio *folio = page_folio(page); 2622 struct page *head = &folio->page; 2623 struct deferred_split *ds_queue = get_deferred_split_queue(head); 2624 XA_STATE(xas, &head->mapping->i_pages, head->index); 2625 struct anon_vma *anon_vma = NULL; 2626 struct address_space *mapping = NULL; 2627 int extra_pins, ret; 2628 pgoff_t end; 2629 bool is_hzp; 2630 2631 VM_BUG_ON_PAGE(!PageLocked(head), head); 2632 VM_BUG_ON_PAGE(!PageCompound(head), head); 2633 2634 is_hzp = is_huge_zero_page(head); 2635 VM_WARN_ON_ONCE_PAGE(is_hzp, head); 2636 if (is_hzp) 2637 return -EBUSY; 2638 2639 if (PageWriteback(head)) 2640 return -EBUSY; 2641 2642 if (PageAnon(head)) { 2643 /* 2644 * The caller does not necessarily hold an mmap_lock that would 2645 * prevent the anon_vma disappearing so we first we take a 2646 * reference to it and then lock the anon_vma for write. This 2647 * is similar to folio_lock_anon_vma_read except the write lock 2648 * is taken to serialise against parallel split or collapse 2649 * operations. 2650 */ 2651 anon_vma = page_get_anon_vma(head); 2652 if (!anon_vma) { 2653 ret = -EBUSY; 2654 goto out; 2655 } 2656 end = -1; 2657 mapping = NULL; 2658 anon_vma_lock_write(anon_vma); 2659 } else { 2660 gfp_t gfp; 2661 2662 mapping = head->mapping; 2663 2664 /* Truncated ? */ 2665 if (!mapping) { 2666 ret = -EBUSY; 2667 goto out; 2668 } 2669 2670 gfp = current_gfp_context(mapping_gfp_mask(mapping) & 2671 GFP_RECLAIM_MASK); 2672 2673 if (folio_test_private(folio) && 2674 !filemap_release_folio(folio, gfp)) { 2675 ret = -EBUSY; 2676 goto out; 2677 } 2678 2679 xas_split_alloc(&xas, head, compound_order(head), gfp); 2680 if (xas_error(&xas)) { 2681 ret = xas_error(&xas); 2682 goto out; 2683 } 2684 2685 anon_vma = NULL; 2686 i_mmap_lock_read(mapping); 2687 2688 /* 2689 *__split_huge_page() may need to trim off pages beyond EOF: 2690 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2691 * which cannot be nested inside the page tree lock. So note 2692 * end now: i_size itself may be changed at any moment, but 2693 * head page lock is good enough to serialize the trimming. 2694 */ 2695 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2696 if (shmem_mapping(mapping)) 2697 end = shmem_fallocend(mapping->host, end); 2698 } 2699 2700 /* 2701 * Racy check if we can split the page, before unmap_page() will 2702 * split PMDs 2703 */ 2704 if (!can_split_folio(folio, &extra_pins)) { 2705 ret = -EBUSY; 2706 goto out_unlock; 2707 } 2708 2709 unmap_page(head); 2710 2711 /* block interrupt reentry in xa_lock and spinlock */ 2712 local_irq_disable(); 2713 if (mapping) { 2714 /* 2715 * Check if the head page is present in page cache. 2716 * We assume all tail are present too, if head is there. 2717 */ 2718 xas_lock(&xas); 2719 xas_reset(&xas); 2720 if (xas_load(&xas) != head) 2721 goto fail; 2722 } 2723 2724 /* Prevent deferred_split_scan() touching ->_refcount */ 2725 spin_lock(&ds_queue->split_queue_lock); 2726 if (page_ref_freeze(head, 1 + extra_pins)) { 2727 if (!list_empty(page_deferred_list(head))) { 2728 ds_queue->split_queue_len--; 2729 list_del(page_deferred_list(head)); 2730 } 2731 spin_unlock(&ds_queue->split_queue_lock); 2732 if (mapping) { 2733 int nr = thp_nr_pages(head); 2734 2735 xas_split(&xas, head, thp_order(head)); 2736 if (PageSwapBacked(head)) { 2737 __mod_lruvec_page_state(head, NR_SHMEM_THPS, 2738 -nr); 2739 } else { 2740 __mod_lruvec_page_state(head, NR_FILE_THPS, 2741 -nr); 2742 filemap_nr_thps_dec(mapping); 2743 } 2744 } 2745 2746 __split_huge_page(page, list, end); 2747 ret = 0; 2748 } else { 2749 spin_unlock(&ds_queue->split_queue_lock); 2750 fail: 2751 if (mapping) 2752 xas_unlock(&xas); 2753 local_irq_enable(); 2754 remap_page(folio, folio_nr_pages(folio)); 2755 ret = -EBUSY; 2756 } 2757 2758 out_unlock: 2759 if (anon_vma) { 2760 anon_vma_unlock_write(anon_vma); 2761 put_anon_vma(anon_vma); 2762 } 2763 if (mapping) 2764 i_mmap_unlock_read(mapping); 2765 out: 2766 xas_destroy(&xas); 2767 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2768 return ret; 2769 } 2770 2771 void free_transhuge_page(struct page *page) 2772 { 2773 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2774 unsigned long flags; 2775 2776 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2777 if (!list_empty(page_deferred_list(page))) { 2778 ds_queue->split_queue_len--; 2779 list_del(page_deferred_list(page)); 2780 } 2781 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2782 free_compound_page(page); 2783 } 2784 2785 void deferred_split_huge_page(struct page *page) 2786 { 2787 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2788 #ifdef CONFIG_MEMCG 2789 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 2790 #endif 2791 unsigned long flags; 2792 2793 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2794 2795 /* 2796 * The try_to_unmap() in page reclaim path might reach here too, 2797 * this may cause a race condition to corrupt deferred split queue. 2798 * And, if page reclaim is already handling the same page, it is 2799 * unnecessary to handle it again in shrinker. 2800 * 2801 * Check PageSwapCache to determine if the page is being 2802 * handled by page reclaim since THP swap would add the page into 2803 * swap cache before calling try_to_unmap(). 2804 */ 2805 if (PageSwapCache(page)) 2806 return; 2807 2808 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2809 if (list_empty(page_deferred_list(page))) { 2810 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2811 list_add_tail(page_deferred_list(page), &ds_queue->split_queue); 2812 ds_queue->split_queue_len++; 2813 #ifdef CONFIG_MEMCG 2814 if (memcg) 2815 set_shrinker_bit(memcg, page_to_nid(page), 2816 deferred_split_shrinker.id); 2817 #endif 2818 } 2819 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2820 } 2821 2822 static unsigned long deferred_split_count(struct shrinker *shrink, 2823 struct shrink_control *sc) 2824 { 2825 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2826 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2827 2828 #ifdef CONFIG_MEMCG 2829 if (sc->memcg) 2830 ds_queue = &sc->memcg->deferred_split_queue; 2831 #endif 2832 return READ_ONCE(ds_queue->split_queue_len); 2833 } 2834 2835 static unsigned long deferred_split_scan(struct shrinker *shrink, 2836 struct shrink_control *sc) 2837 { 2838 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2839 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2840 unsigned long flags; 2841 LIST_HEAD(list), *pos, *next; 2842 struct page *page; 2843 int split = 0; 2844 2845 #ifdef CONFIG_MEMCG 2846 if (sc->memcg) 2847 ds_queue = &sc->memcg->deferred_split_queue; 2848 #endif 2849 2850 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2851 /* Take pin on all head pages to avoid freeing them under us */ 2852 list_for_each_safe(pos, next, &ds_queue->split_queue) { 2853 page = list_entry((void *)pos, struct page, deferred_list); 2854 page = compound_head(page); 2855 if (get_page_unless_zero(page)) { 2856 list_move(page_deferred_list(page), &list); 2857 } else { 2858 /* We lost race with put_compound_page() */ 2859 list_del_init(page_deferred_list(page)); 2860 ds_queue->split_queue_len--; 2861 } 2862 if (!--sc->nr_to_scan) 2863 break; 2864 } 2865 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2866 2867 list_for_each_safe(pos, next, &list) { 2868 page = list_entry((void *)pos, struct page, deferred_list); 2869 if (!trylock_page(page)) 2870 goto next; 2871 /* split_huge_page() removes page from list on success */ 2872 if (!split_huge_page(page)) 2873 split++; 2874 unlock_page(page); 2875 next: 2876 put_page(page); 2877 } 2878 2879 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2880 list_splice_tail(&list, &ds_queue->split_queue); 2881 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2882 2883 /* 2884 * Stop shrinker if we didn't split any page, but the queue is empty. 2885 * This can happen if pages were freed under us. 2886 */ 2887 if (!split && list_empty(&ds_queue->split_queue)) 2888 return SHRINK_STOP; 2889 return split; 2890 } 2891 2892 static struct shrinker deferred_split_shrinker = { 2893 .count_objects = deferred_split_count, 2894 .scan_objects = deferred_split_scan, 2895 .seeks = DEFAULT_SEEKS, 2896 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | 2897 SHRINKER_NONSLAB, 2898 }; 2899 2900 #ifdef CONFIG_DEBUG_FS 2901 static void split_huge_pages_all(void) 2902 { 2903 struct zone *zone; 2904 struct page *page; 2905 unsigned long pfn, max_zone_pfn; 2906 unsigned long total = 0, split = 0; 2907 2908 pr_debug("Split all THPs\n"); 2909 for_each_zone(zone) { 2910 if (!managed_zone(zone)) 2911 continue; 2912 max_zone_pfn = zone_end_pfn(zone); 2913 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2914 int nr_pages; 2915 2916 page = pfn_to_online_page(pfn); 2917 if (!page || !get_page_unless_zero(page)) 2918 continue; 2919 2920 if (zone != page_zone(page)) 2921 goto next; 2922 2923 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 2924 goto next; 2925 2926 total++; 2927 lock_page(page); 2928 nr_pages = thp_nr_pages(page); 2929 if (!split_huge_page(page)) 2930 split++; 2931 pfn += nr_pages - 1; 2932 unlock_page(page); 2933 next: 2934 put_page(page); 2935 cond_resched(); 2936 } 2937 } 2938 2939 pr_debug("%lu of %lu THP split\n", split, total); 2940 } 2941 2942 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) 2943 { 2944 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || 2945 is_vm_hugetlb_page(vma); 2946 } 2947 2948 static int split_huge_pages_pid(int pid, unsigned long vaddr_start, 2949 unsigned long vaddr_end) 2950 { 2951 int ret = 0; 2952 struct task_struct *task; 2953 struct mm_struct *mm; 2954 unsigned long total = 0, split = 0; 2955 unsigned long addr; 2956 2957 vaddr_start &= PAGE_MASK; 2958 vaddr_end &= PAGE_MASK; 2959 2960 /* Find the task_struct from pid */ 2961 rcu_read_lock(); 2962 task = find_task_by_vpid(pid); 2963 if (!task) { 2964 rcu_read_unlock(); 2965 ret = -ESRCH; 2966 goto out; 2967 } 2968 get_task_struct(task); 2969 rcu_read_unlock(); 2970 2971 /* Find the mm_struct */ 2972 mm = get_task_mm(task); 2973 put_task_struct(task); 2974 2975 if (!mm) { 2976 ret = -EINVAL; 2977 goto out; 2978 } 2979 2980 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n", 2981 pid, vaddr_start, vaddr_end); 2982 2983 mmap_read_lock(mm); 2984 /* 2985 * always increase addr by PAGE_SIZE, since we could have a PTE page 2986 * table filled with PTE-mapped THPs, each of which is distinct. 2987 */ 2988 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { 2989 struct vm_area_struct *vma = vma_lookup(mm, addr); 2990 struct page *page; 2991 2992 if (!vma) 2993 break; 2994 2995 /* skip special VMA and hugetlb VMA */ 2996 if (vma_not_suitable_for_thp_split(vma)) { 2997 addr = vma->vm_end; 2998 continue; 2999 } 3000 3001 /* FOLL_DUMP to ignore special (like zero) pages */ 3002 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); 3003 3004 if (IS_ERR_OR_NULL(page) || is_zone_device_page(page)) 3005 continue; 3006 3007 if (!is_transparent_hugepage(page)) 3008 goto next; 3009 3010 total++; 3011 if (!can_split_folio(page_folio(page), NULL)) 3012 goto next; 3013 3014 if (!trylock_page(page)) 3015 goto next; 3016 3017 if (!split_huge_page(page)) 3018 split++; 3019 3020 unlock_page(page); 3021 next: 3022 put_page(page); 3023 cond_resched(); 3024 } 3025 mmap_read_unlock(mm); 3026 mmput(mm); 3027 3028 pr_debug("%lu of %lu THP split\n", split, total); 3029 3030 out: 3031 return ret; 3032 } 3033 3034 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, 3035 pgoff_t off_end) 3036 { 3037 struct filename *file; 3038 struct file *candidate; 3039 struct address_space *mapping; 3040 int ret = -EINVAL; 3041 pgoff_t index; 3042 int nr_pages = 1; 3043 unsigned long total = 0, split = 0; 3044 3045 file = getname_kernel(file_path); 3046 if (IS_ERR(file)) 3047 return ret; 3048 3049 candidate = file_open_name(file, O_RDONLY, 0); 3050 if (IS_ERR(candidate)) 3051 goto out; 3052 3053 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", 3054 file_path, off_start, off_end); 3055 3056 mapping = candidate->f_mapping; 3057 3058 for (index = off_start; index < off_end; index += nr_pages) { 3059 struct page *fpage = pagecache_get_page(mapping, index, 3060 FGP_ENTRY | FGP_HEAD, 0); 3061 3062 nr_pages = 1; 3063 if (xa_is_value(fpage) || !fpage) 3064 continue; 3065 3066 if (!is_transparent_hugepage(fpage)) 3067 goto next; 3068 3069 total++; 3070 nr_pages = thp_nr_pages(fpage); 3071 3072 if (!trylock_page(fpage)) 3073 goto next; 3074 3075 if (!split_huge_page(fpage)) 3076 split++; 3077 3078 unlock_page(fpage); 3079 next: 3080 put_page(fpage); 3081 cond_resched(); 3082 } 3083 3084 filp_close(candidate, NULL); 3085 ret = 0; 3086 3087 pr_debug("%lu of %lu file-backed THP split\n", split, total); 3088 out: 3089 putname(file); 3090 return ret; 3091 } 3092 3093 #define MAX_INPUT_BUF_SZ 255 3094 3095 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, 3096 size_t count, loff_t *ppops) 3097 { 3098 static DEFINE_MUTEX(split_debug_mutex); 3099 ssize_t ret; 3100 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */ 3101 char input_buf[MAX_INPUT_BUF_SZ]; 3102 int pid; 3103 unsigned long vaddr_start, vaddr_end; 3104 3105 ret = mutex_lock_interruptible(&split_debug_mutex); 3106 if (ret) 3107 return ret; 3108 3109 ret = -EFAULT; 3110 3111 memset(input_buf, 0, MAX_INPUT_BUF_SZ); 3112 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) 3113 goto out; 3114 3115 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; 3116 3117 if (input_buf[0] == '/') { 3118 char *tok; 3119 char *buf = input_buf; 3120 char file_path[MAX_INPUT_BUF_SZ]; 3121 pgoff_t off_start = 0, off_end = 0; 3122 size_t input_len = strlen(input_buf); 3123 3124 tok = strsep(&buf, ","); 3125 if (tok) { 3126 strcpy(file_path, tok); 3127 } else { 3128 ret = -EINVAL; 3129 goto out; 3130 } 3131 3132 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end); 3133 if (ret != 2) { 3134 ret = -EINVAL; 3135 goto out; 3136 } 3137 ret = split_huge_pages_in_file(file_path, off_start, off_end); 3138 if (!ret) 3139 ret = input_len; 3140 3141 goto out; 3142 } 3143 3144 ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end); 3145 if (ret == 1 && pid == 1) { 3146 split_huge_pages_all(); 3147 ret = strlen(input_buf); 3148 goto out; 3149 } else if (ret != 3) { 3150 ret = -EINVAL; 3151 goto out; 3152 } 3153 3154 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end); 3155 if (!ret) 3156 ret = strlen(input_buf); 3157 out: 3158 mutex_unlock(&split_debug_mutex); 3159 return ret; 3160 3161 } 3162 3163 static const struct file_operations split_huge_pages_fops = { 3164 .owner = THIS_MODULE, 3165 .write = split_huge_pages_write, 3166 .llseek = no_llseek, 3167 }; 3168 3169 static int __init split_huge_pages_debugfs(void) 3170 { 3171 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 3172 &split_huge_pages_fops); 3173 return 0; 3174 } 3175 late_initcall(split_huge_pages_debugfs); 3176 #endif 3177 3178 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 3179 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 3180 struct page *page) 3181 { 3182 struct vm_area_struct *vma = pvmw->vma; 3183 struct mm_struct *mm = vma->vm_mm; 3184 unsigned long address = pvmw->address; 3185 bool anon_exclusive; 3186 pmd_t pmdval; 3187 swp_entry_t entry; 3188 pmd_t pmdswp; 3189 3190 if (!(pvmw->pmd && !pvmw->pte)) 3191 return 0; 3192 3193 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 3194 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 3195 3196 /* See page_try_share_anon_rmap(): invalidate PMD first. */ 3197 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 3198 if (anon_exclusive && page_try_share_anon_rmap(page)) { 3199 set_pmd_at(mm, address, pvmw->pmd, pmdval); 3200 return -EBUSY; 3201 } 3202 3203 if (pmd_dirty(pmdval)) 3204 set_page_dirty(page); 3205 if (pmd_write(pmdval)) 3206 entry = make_writable_migration_entry(page_to_pfn(page)); 3207 else if (anon_exclusive) 3208 entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); 3209 else 3210 entry = make_readable_migration_entry(page_to_pfn(page)); 3211 if (pmd_young(pmdval)) 3212 entry = make_migration_entry_young(entry); 3213 if (pmd_dirty(pmdval)) 3214 entry = make_migration_entry_dirty(entry); 3215 pmdswp = swp_entry_to_pmd(entry); 3216 if (pmd_soft_dirty(pmdval)) 3217 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3218 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3219 page_remove_rmap(page, vma, true); 3220 put_page(page); 3221 trace_set_migration_pmd(address, pmd_val(pmdswp)); 3222 3223 return 0; 3224 } 3225 3226 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3227 { 3228 struct vm_area_struct *vma = pvmw->vma; 3229 struct mm_struct *mm = vma->vm_mm; 3230 unsigned long address = pvmw->address; 3231 unsigned long haddr = address & HPAGE_PMD_MASK; 3232 pmd_t pmde; 3233 swp_entry_t entry; 3234 3235 if (!(pvmw->pmd && !pvmw->pte)) 3236 return; 3237 3238 entry = pmd_to_swp_entry(*pvmw->pmd); 3239 get_page(new); 3240 pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot)); 3241 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3242 pmde = pmd_mksoft_dirty(pmde); 3243 if (is_writable_migration_entry(entry)) 3244 pmde = maybe_pmd_mkwrite(pmde, vma); 3245 if (pmd_swp_uffd_wp(*pvmw->pmd)) 3246 pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde)); 3247 if (!is_migration_entry_young(entry)) 3248 pmde = pmd_mkold(pmde); 3249 /* NOTE: this may contain setting soft-dirty on some archs */ 3250 if (PageDirty(new) && is_migration_entry_dirty(entry)) 3251 pmde = pmd_mkdirty(pmde); 3252 3253 if (PageAnon(new)) { 3254 rmap_t rmap_flags = RMAP_COMPOUND; 3255 3256 if (!is_readable_migration_entry(entry)) 3257 rmap_flags |= RMAP_EXCLUSIVE; 3258 3259 page_add_anon_rmap(new, vma, haddr, rmap_flags); 3260 } else { 3261 page_add_file_rmap(new, vma, true); 3262 } 3263 VM_BUG_ON(pmd_write(pmde) && PageAnon(new) && !PageAnonExclusive(new)); 3264 set_pmd_at(mm, haddr, pvmw->pmd, pmde); 3265 3266 /* No need to invalidate - it was non-present before */ 3267 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3268 trace_remove_migration_pmd(address, pmd_val(pmde)); 3269 } 3270 #endif 3271