1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2009 Red Hat, Inc. 4 */ 5 6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 7 8 #include <linux/mm.h> 9 #include <linux/sched.h> 10 #include <linux/sched/mm.h> 11 #include <linux/sched/coredump.h> 12 #include <linux/sched/numa_balancing.h> 13 #include <linux/highmem.h> 14 #include <linux/hugetlb.h> 15 #include <linux/mmu_notifier.h> 16 #include <linux/rmap.h> 17 #include <linux/swap.h> 18 #include <linux/shrinker.h> 19 #include <linux/mm_inline.h> 20 #include <linux/swapops.h> 21 #include <linux/backing-dev.h> 22 #include <linux/dax.h> 23 #include <linux/khugepaged.h> 24 #include <linux/freezer.h> 25 #include <linux/pfn_t.h> 26 #include <linux/mman.h> 27 #include <linux/memremap.h> 28 #include <linux/pagemap.h> 29 #include <linux/debugfs.h> 30 #include <linux/migrate.h> 31 #include <linux/hashtable.h> 32 #include <linux/userfaultfd_k.h> 33 #include <linux/page_idle.h> 34 #include <linux/shmem_fs.h> 35 #include <linux/oom.h> 36 #include <linux/numa.h> 37 #include <linux/page_owner.h> 38 #include <linux/sched/sysctl.h> 39 #include <linux/memory-tiers.h> 40 41 #include <asm/tlb.h> 42 #include <asm/pgalloc.h> 43 #include "internal.h" 44 #include "swap.h" 45 46 #define CREATE_TRACE_POINTS 47 #include <trace/events/thp.h> 48 49 /* 50 * By default, transparent hugepage support is disabled in order to avoid 51 * risking an increased memory footprint for applications that are not 52 * guaranteed to benefit from it. When transparent hugepage support is 53 * enabled, it is for all mappings, and khugepaged scans all mappings. 54 * Defrag is invoked by khugepaged hugepage allocations and by page faults 55 * for all hugepage allocations. 56 */ 57 unsigned long transparent_hugepage_flags __read_mostly = 58 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 59 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 60 #endif 61 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 62 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 63 #endif 64 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 65 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 66 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 67 68 static struct shrinker deferred_split_shrinker; 69 70 static atomic_t huge_zero_refcount; 71 struct page *huge_zero_page __read_mostly; 72 unsigned long huge_zero_pfn __read_mostly = ~0UL; 73 74 bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags, 75 bool smaps, bool in_pf, bool enforce_sysfs) 76 { 77 if (!vma->vm_mm) /* vdso */ 78 return false; 79 80 /* 81 * Explicitly disabled through madvise or prctl, or some 82 * architectures may disable THP for some mappings, for 83 * example, s390 kvm. 84 * */ 85 if ((vm_flags & VM_NOHUGEPAGE) || 86 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) 87 return false; 88 /* 89 * If the hardware/firmware marked hugepage support disabled. 90 */ 91 if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER_DAX)) 92 return false; 93 94 /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ 95 if (vma_is_dax(vma)) 96 return in_pf; 97 98 /* 99 * Special VMA and hugetlb VMA. 100 * Must be checked after dax since some dax mappings may have 101 * VM_MIXEDMAP set. 102 */ 103 if (vm_flags & VM_NO_KHUGEPAGED) 104 return false; 105 106 /* 107 * Check alignment for file vma and size for both file and anon vma. 108 * 109 * Skip the check for page fault. Huge fault does the check in fault 110 * handlers. And this check is not suitable for huge PUD fault. 111 */ 112 if (!in_pf && 113 !transhuge_vma_suitable(vma, (vma->vm_end - HPAGE_PMD_SIZE))) 114 return false; 115 116 /* 117 * Enabled via shmem mount options or sysfs settings. 118 * Must be done before hugepage flags check since shmem has its 119 * own flags. 120 */ 121 if (!in_pf && shmem_file(vma->vm_file)) 122 return shmem_huge_enabled(vma, !enforce_sysfs); 123 124 /* Enforce sysfs THP requirements as necessary */ 125 if (enforce_sysfs && 126 (!hugepage_flags_enabled() || (!(vm_flags & VM_HUGEPAGE) && 127 !hugepage_flags_always()))) 128 return false; 129 130 /* Only regular file is valid */ 131 if (!in_pf && file_thp_enabled(vma)) 132 return true; 133 134 if (!vma_is_anonymous(vma)) 135 return false; 136 137 if (vma_is_temporary_stack(vma)) 138 return false; 139 140 /* 141 * THPeligible bit of smaps should show 1 for proper VMAs even 142 * though anon_vma is not initialized yet. 143 * 144 * Allow page fault since anon_vma may be not initialized until 145 * the first page fault. 146 */ 147 if (!vma->anon_vma) 148 return (smaps || in_pf); 149 150 return true; 151 } 152 153 static bool get_huge_zero_page(void) 154 { 155 struct page *zero_page; 156 retry: 157 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 158 return true; 159 160 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 161 HPAGE_PMD_ORDER); 162 if (!zero_page) { 163 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 164 return false; 165 } 166 preempt_disable(); 167 if (cmpxchg(&huge_zero_page, NULL, zero_page)) { 168 preempt_enable(); 169 __free_pages(zero_page, compound_order(zero_page)); 170 goto retry; 171 } 172 WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page)); 173 174 /* We take additional reference here. It will be put back by shrinker */ 175 atomic_set(&huge_zero_refcount, 2); 176 preempt_enable(); 177 count_vm_event(THP_ZERO_PAGE_ALLOC); 178 return true; 179 } 180 181 static void put_huge_zero_page(void) 182 { 183 /* 184 * Counter should never go to zero here. Only shrinker can put 185 * last reference. 186 */ 187 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 188 } 189 190 struct page *mm_get_huge_zero_page(struct mm_struct *mm) 191 { 192 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 193 return READ_ONCE(huge_zero_page); 194 195 if (!get_huge_zero_page()) 196 return NULL; 197 198 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 199 put_huge_zero_page(); 200 201 return READ_ONCE(huge_zero_page); 202 } 203 204 void mm_put_huge_zero_page(struct mm_struct *mm) 205 { 206 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 207 put_huge_zero_page(); 208 } 209 210 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 211 struct shrink_control *sc) 212 { 213 /* we can free zero page only if last reference remains */ 214 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 215 } 216 217 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 218 struct shrink_control *sc) 219 { 220 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 221 struct page *zero_page = xchg(&huge_zero_page, NULL); 222 BUG_ON(zero_page == NULL); 223 WRITE_ONCE(huge_zero_pfn, ~0UL); 224 __free_pages(zero_page, compound_order(zero_page)); 225 return HPAGE_PMD_NR; 226 } 227 228 return 0; 229 } 230 231 static struct shrinker huge_zero_page_shrinker = { 232 .count_objects = shrink_huge_zero_page_count, 233 .scan_objects = shrink_huge_zero_page_scan, 234 .seeks = DEFAULT_SEEKS, 235 }; 236 237 #ifdef CONFIG_SYSFS 238 static ssize_t enabled_show(struct kobject *kobj, 239 struct kobj_attribute *attr, char *buf) 240 { 241 const char *output; 242 243 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 244 output = "[always] madvise never"; 245 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 246 &transparent_hugepage_flags)) 247 output = "always [madvise] never"; 248 else 249 output = "always madvise [never]"; 250 251 return sysfs_emit(buf, "%s\n", output); 252 } 253 254 static ssize_t enabled_store(struct kobject *kobj, 255 struct kobj_attribute *attr, 256 const char *buf, size_t count) 257 { 258 ssize_t ret = count; 259 260 if (sysfs_streq(buf, "always")) { 261 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 262 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 263 } else if (sysfs_streq(buf, "madvise")) { 264 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 265 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 266 } else if (sysfs_streq(buf, "never")) { 267 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 268 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 269 } else 270 ret = -EINVAL; 271 272 if (ret > 0) { 273 int err = start_stop_khugepaged(); 274 if (err) 275 ret = err; 276 } 277 return ret; 278 } 279 280 static struct kobj_attribute enabled_attr = __ATTR_RW(enabled); 281 282 ssize_t single_hugepage_flag_show(struct kobject *kobj, 283 struct kobj_attribute *attr, char *buf, 284 enum transparent_hugepage_flag flag) 285 { 286 return sysfs_emit(buf, "%d\n", 287 !!test_bit(flag, &transparent_hugepage_flags)); 288 } 289 290 ssize_t single_hugepage_flag_store(struct kobject *kobj, 291 struct kobj_attribute *attr, 292 const char *buf, size_t count, 293 enum transparent_hugepage_flag flag) 294 { 295 unsigned long value; 296 int ret; 297 298 ret = kstrtoul(buf, 10, &value); 299 if (ret < 0) 300 return ret; 301 if (value > 1) 302 return -EINVAL; 303 304 if (value) 305 set_bit(flag, &transparent_hugepage_flags); 306 else 307 clear_bit(flag, &transparent_hugepage_flags); 308 309 return count; 310 } 311 312 static ssize_t defrag_show(struct kobject *kobj, 313 struct kobj_attribute *attr, char *buf) 314 { 315 const char *output; 316 317 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 318 &transparent_hugepage_flags)) 319 output = "[always] defer defer+madvise madvise never"; 320 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 321 &transparent_hugepage_flags)) 322 output = "always [defer] defer+madvise madvise never"; 323 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 324 &transparent_hugepage_flags)) 325 output = "always defer [defer+madvise] madvise never"; 326 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 327 &transparent_hugepage_flags)) 328 output = "always defer defer+madvise [madvise] never"; 329 else 330 output = "always defer defer+madvise madvise [never]"; 331 332 return sysfs_emit(buf, "%s\n", output); 333 } 334 335 static ssize_t defrag_store(struct kobject *kobj, 336 struct kobj_attribute *attr, 337 const char *buf, size_t count) 338 { 339 if (sysfs_streq(buf, "always")) { 340 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 341 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 342 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 343 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 344 } else if (sysfs_streq(buf, "defer+madvise")) { 345 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 346 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 347 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 348 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 349 } else if (sysfs_streq(buf, "defer")) { 350 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 351 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 352 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 353 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 354 } else if (sysfs_streq(buf, "madvise")) { 355 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 356 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 357 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 358 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 359 } else if (sysfs_streq(buf, "never")) { 360 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 361 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 362 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 363 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 364 } else 365 return -EINVAL; 366 367 return count; 368 } 369 static struct kobj_attribute defrag_attr = __ATTR_RW(defrag); 370 371 static ssize_t use_zero_page_show(struct kobject *kobj, 372 struct kobj_attribute *attr, char *buf) 373 { 374 return single_hugepage_flag_show(kobj, attr, buf, 375 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 376 } 377 static ssize_t use_zero_page_store(struct kobject *kobj, 378 struct kobj_attribute *attr, const char *buf, size_t count) 379 { 380 return single_hugepage_flag_store(kobj, attr, buf, count, 381 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 382 } 383 static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page); 384 385 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 386 struct kobj_attribute *attr, char *buf) 387 { 388 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); 389 } 390 static struct kobj_attribute hpage_pmd_size_attr = 391 __ATTR_RO(hpage_pmd_size); 392 393 static struct attribute *hugepage_attr[] = { 394 &enabled_attr.attr, 395 &defrag_attr.attr, 396 &use_zero_page_attr.attr, 397 &hpage_pmd_size_attr.attr, 398 #ifdef CONFIG_SHMEM 399 &shmem_enabled_attr.attr, 400 #endif 401 NULL, 402 }; 403 404 static const struct attribute_group hugepage_attr_group = { 405 .attrs = hugepage_attr, 406 }; 407 408 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 409 { 410 int err; 411 412 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 413 if (unlikely(!*hugepage_kobj)) { 414 pr_err("failed to create transparent hugepage kobject\n"); 415 return -ENOMEM; 416 } 417 418 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 419 if (err) { 420 pr_err("failed to register transparent hugepage group\n"); 421 goto delete_obj; 422 } 423 424 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 425 if (err) { 426 pr_err("failed to register transparent hugepage group\n"); 427 goto remove_hp_group; 428 } 429 430 return 0; 431 432 remove_hp_group: 433 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 434 delete_obj: 435 kobject_put(*hugepage_kobj); 436 return err; 437 } 438 439 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 440 { 441 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 442 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 443 kobject_put(hugepage_kobj); 444 } 445 #else 446 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 447 { 448 return 0; 449 } 450 451 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 452 { 453 } 454 #endif /* CONFIG_SYSFS */ 455 456 static int __init hugepage_init(void) 457 { 458 int err; 459 struct kobject *hugepage_kobj; 460 461 if (!has_transparent_hugepage()) { 462 /* 463 * Hardware doesn't support hugepages, hence disable 464 * DAX PMD support. 465 */ 466 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX; 467 return -EINVAL; 468 } 469 470 /* 471 * hugepages can't be allocated by the buddy allocator 472 */ 473 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); 474 /* 475 * we use page->mapping and page->index in second tail page 476 * as list_head: assuming THP order >= 2 477 */ 478 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); 479 480 err = hugepage_init_sysfs(&hugepage_kobj); 481 if (err) 482 goto err_sysfs; 483 484 err = khugepaged_init(); 485 if (err) 486 goto err_slab; 487 488 err = register_shrinker(&huge_zero_page_shrinker, "thp-zero"); 489 if (err) 490 goto err_hzp_shrinker; 491 err = register_shrinker(&deferred_split_shrinker, "thp-deferred_split"); 492 if (err) 493 goto err_split_shrinker; 494 495 /* 496 * By default disable transparent hugepages on smaller systems, 497 * where the extra memory used could hurt more than TLB overhead 498 * is likely to save. The admin can still enable it through /sys. 499 */ 500 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 501 transparent_hugepage_flags = 0; 502 return 0; 503 } 504 505 err = start_stop_khugepaged(); 506 if (err) 507 goto err_khugepaged; 508 509 return 0; 510 err_khugepaged: 511 unregister_shrinker(&deferred_split_shrinker); 512 err_split_shrinker: 513 unregister_shrinker(&huge_zero_page_shrinker); 514 err_hzp_shrinker: 515 khugepaged_destroy(); 516 err_slab: 517 hugepage_exit_sysfs(hugepage_kobj); 518 err_sysfs: 519 return err; 520 } 521 subsys_initcall(hugepage_init); 522 523 static int __init setup_transparent_hugepage(char *str) 524 { 525 int ret = 0; 526 if (!str) 527 goto out; 528 if (!strcmp(str, "always")) { 529 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 530 &transparent_hugepage_flags); 531 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 532 &transparent_hugepage_flags); 533 ret = 1; 534 } else if (!strcmp(str, "madvise")) { 535 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 536 &transparent_hugepage_flags); 537 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 538 &transparent_hugepage_flags); 539 ret = 1; 540 } else if (!strcmp(str, "never")) { 541 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 542 &transparent_hugepage_flags); 543 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 544 &transparent_hugepage_flags); 545 ret = 1; 546 } 547 out: 548 if (!ret) 549 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 550 return ret; 551 } 552 __setup("transparent_hugepage=", setup_transparent_hugepage); 553 554 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 555 { 556 if (likely(vma->vm_flags & VM_WRITE)) 557 pmd = pmd_mkwrite(pmd); 558 return pmd; 559 } 560 561 #ifdef CONFIG_MEMCG 562 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 563 { 564 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 565 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 566 567 if (memcg) 568 return &memcg->deferred_split_queue; 569 else 570 return &pgdat->deferred_split_queue; 571 } 572 #else 573 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 574 { 575 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 576 577 return &pgdat->deferred_split_queue; 578 } 579 #endif 580 581 void prep_transhuge_page(struct page *page) 582 { 583 /* 584 * we use page->mapping and page->index in second tail page 585 * as list_head: assuming THP order >= 2 586 */ 587 588 INIT_LIST_HEAD(page_deferred_list(page)); 589 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); 590 } 591 592 static inline bool is_transparent_hugepage(struct page *page) 593 { 594 if (!PageCompound(page)) 595 return false; 596 597 page = compound_head(page); 598 return is_huge_zero_page(page) || 599 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR; 600 } 601 602 static unsigned long __thp_get_unmapped_area(struct file *filp, 603 unsigned long addr, unsigned long len, 604 loff_t off, unsigned long flags, unsigned long size) 605 { 606 loff_t off_end = off + len; 607 loff_t off_align = round_up(off, size); 608 unsigned long len_pad, ret; 609 610 if (off_end <= off_align || (off_end - off_align) < size) 611 return 0; 612 613 len_pad = len + size; 614 if (len_pad < len || (off + len_pad) < off) 615 return 0; 616 617 ret = current->mm->get_unmapped_area(filp, addr, len_pad, 618 off >> PAGE_SHIFT, flags); 619 620 /* 621 * The failure might be due to length padding. The caller will retry 622 * without the padding. 623 */ 624 if (IS_ERR_VALUE(ret)) 625 return 0; 626 627 /* 628 * Do not try to align to THP boundary if allocation at the address 629 * hint succeeds. 630 */ 631 if (ret == addr) 632 return addr; 633 634 ret += (off - ret) & (size - 1); 635 return ret; 636 } 637 638 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 639 unsigned long len, unsigned long pgoff, unsigned long flags) 640 { 641 unsigned long ret; 642 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 643 644 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE); 645 if (ret) 646 return ret; 647 648 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 649 } 650 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 651 652 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 653 struct page *page, gfp_t gfp) 654 { 655 struct vm_area_struct *vma = vmf->vma; 656 pgtable_t pgtable; 657 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 658 vm_fault_t ret = 0; 659 660 VM_BUG_ON_PAGE(!PageCompound(page), page); 661 662 if (mem_cgroup_charge(page_folio(page), vma->vm_mm, gfp)) { 663 put_page(page); 664 count_vm_event(THP_FAULT_FALLBACK); 665 count_vm_event(THP_FAULT_FALLBACK_CHARGE); 666 return VM_FAULT_FALLBACK; 667 } 668 cgroup_throttle_swaprate(page, gfp); 669 670 pgtable = pte_alloc_one(vma->vm_mm); 671 if (unlikely(!pgtable)) { 672 ret = VM_FAULT_OOM; 673 goto release; 674 } 675 676 clear_huge_page(page, vmf->address, HPAGE_PMD_NR); 677 /* 678 * The memory barrier inside __SetPageUptodate makes sure that 679 * clear_huge_page writes become visible before the set_pmd_at() 680 * write. 681 */ 682 __SetPageUptodate(page); 683 684 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 685 if (unlikely(!pmd_none(*vmf->pmd))) { 686 goto unlock_release; 687 } else { 688 pmd_t entry; 689 690 ret = check_stable_address_space(vma->vm_mm); 691 if (ret) 692 goto unlock_release; 693 694 /* Deliver the page fault to userland */ 695 if (userfaultfd_missing(vma)) { 696 spin_unlock(vmf->ptl); 697 put_page(page); 698 pte_free(vma->vm_mm, pgtable); 699 ret = handle_userfault(vmf, VM_UFFD_MISSING); 700 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 701 return ret; 702 } 703 704 entry = mk_huge_pmd(page, vma->vm_page_prot); 705 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 706 page_add_new_anon_rmap(page, vma, haddr); 707 lru_cache_add_inactive_or_unevictable(page, vma); 708 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 709 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 710 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 711 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 712 mm_inc_nr_ptes(vma->vm_mm); 713 spin_unlock(vmf->ptl); 714 count_vm_event(THP_FAULT_ALLOC); 715 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); 716 } 717 718 return 0; 719 unlock_release: 720 spin_unlock(vmf->ptl); 721 release: 722 if (pgtable) 723 pte_free(vma->vm_mm, pgtable); 724 put_page(page); 725 return ret; 726 727 } 728 729 /* 730 * always: directly stall for all thp allocations 731 * defer: wake kswapd and fail if not immediately available 732 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 733 * fail if not immediately available 734 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 735 * available 736 * never: never stall for any thp allocation 737 */ 738 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) 739 { 740 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); 741 742 /* Always do synchronous compaction */ 743 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 744 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 745 746 /* Kick kcompactd and fail quickly */ 747 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 748 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; 749 750 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 751 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 752 return GFP_TRANSHUGE_LIGHT | 753 (vma_madvised ? __GFP_DIRECT_RECLAIM : 754 __GFP_KSWAPD_RECLAIM); 755 756 /* Only do synchronous compaction if madvised */ 757 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 758 return GFP_TRANSHUGE_LIGHT | 759 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 760 761 return GFP_TRANSHUGE_LIGHT; 762 } 763 764 /* Caller must hold page table lock. */ 765 static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, 766 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 767 struct page *zero_page) 768 { 769 pmd_t entry; 770 if (!pmd_none(*pmd)) 771 return; 772 entry = mk_pmd(zero_page, vma->vm_page_prot); 773 entry = pmd_mkhuge(entry); 774 pgtable_trans_huge_deposit(mm, pmd, pgtable); 775 set_pmd_at(mm, haddr, pmd, entry); 776 mm_inc_nr_ptes(mm); 777 } 778 779 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 780 { 781 struct vm_area_struct *vma = vmf->vma; 782 gfp_t gfp; 783 struct folio *folio; 784 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 785 786 if (!transhuge_vma_suitable(vma, haddr)) 787 return VM_FAULT_FALLBACK; 788 if (unlikely(anon_vma_prepare(vma))) 789 return VM_FAULT_OOM; 790 khugepaged_enter_vma(vma, vma->vm_flags); 791 792 if (!(vmf->flags & FAULT_FLAG_WRITE) && 793 !mm_forbids_zeropage(vma->vm_mm) && 794 transparent_hugepage_use_zero_page()) { 795 pgtable_t pgtable; 796 struct page *zero_page; 797 vm_fault_t ret; 798 pgtable = pte_alloc_one(vma->vm_mm); 799 if (unlikely(!pgtable)) 800 return VM_FAULT_OOM; 801 zero_page = mm_get_huge_zero_page(vma->vm_mm); 802 if (unlikely(!zero_page)) { 803 pte_free(vma->vm_mm, pgtable); 804 count_vm_event(THP_FAULT_FALLBACK); 805 return VM_FAULT_FALLBACK; 806 } 807 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 808 ret = 0; 809 if (pmd_none(*vmf->pmd)) { 810 ret = check_stable_address_space(vma->vm_mm); 811 if (ret) { 812 spin_unlock(vmf->ptl); 813 pte_free(vma->vm_mm, pgtable); 814 } else if (userfaultfd_missing(vma)) { 815 spin_unlock(vmf->ptl); 816 pte_free(vma->vm_mm, pgtable); 817 ret = handle_userfault(vmf, VM_UFFD_MISSING); 818 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 819 } else { 820 set_huge_zero_page(pgtable, vma->vm_mm, vma, 821 haddr, vmf->pmd, zero_page); 822 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 823 spin_unlock(vmf->ptl); 824 } 825 } else { 826 spin_unlock(vmf->ptl); 827 pte_free(vma->vm_mm, pgtable); 828 } 829 return ret; 830 } 831 gfp = vma_thp_gfp_mask(vma); 832 folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true); 833 if (unlikely(!folio)) { 834 count_vm_event(THP_FAULT_FALLBACK); 835 return VM_FAULT_FALLBACK; 836 } 837 return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp); 838 } 839 840 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 841 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 842 pgtable_t pgtable) 843 { 844 struct mm_struct *mm = vma->vm_mm; 845 pmd_t entry; 846 spinlock_t *ptl; 847 848 ptl = pmd_lock(mm, pmd); 849 if (!pmd_none(*pmd)) { 850 if (write) { 851 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 852 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 853 goto out_unlock; 854 } 855 entry = pmd_mkyoung(*pmd); 856 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 857 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 858 update_mmu_cache_pmd(vma, addr, pmd); 859 } 860 861 goto out_unlock; 862 } 863 864 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 865 if (pfn_t_devmap(pfn)) 866 entry = pmd_mkdevmap(entry); 867 if (write) { 868 entry = pmd_mkyoung(pmd_mkdirty(entry)); 869 entry = maybe_pmd_mkwrite(entry, vma); 870 } 871 872 if (pgtable) { 873 pgtable_trans_huge_deposit(mm, pmd, pgtable); 874 mm_inc_nr_ptes(mm); 875 pgtable = NULL; 876 } 877 878 set_pmd_at(mm, addr, pmd, entry); 879 update_mmu_cache_pmd(vma, addr, pmd); 880 881 out_unlock: 882 spin_unlock(ptl); 883 if (pgtable) 884 pte_free(mm, pgtable); 885 } 886 887 /** 888 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn 889 * @vmf: Structure describing the fault 890 * @pfn: pfn to insert 891 * @pgprot: page protection to use 892 * @write: whether it's a write fault 893 * 894 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and 895 * also consult the vmf_insert_mixed_prot() documentation when 896 * @pgprot != @vmf->vma->vm_page_prot. 897 * 898 * Return: vm_fault_t value. 899 */ 900 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn, 901 pgprot_t pgprot, bool write) 902 { 903 unsigned long addr = vmf->address & PMD_MASK; 904 struct vm_area_struct *vma = vmf->vma; 905 pgtable_t pgtable = NULL; 906 907 /* 908 * If we had pmd_special, we could avoid all these restrictions, 909 * but we need to be consistent with PTEs and architectures that 910 * can't support a 'special' bit. 911 */ 912 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 913 !pfn_t_devmap(pfn)); 914 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 915 (VM_PFNMAP|VM_MIXEDMAP)); 916 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 917 918 if (addr < vma->vm_start || addr >= vma->vm_end) 919 return VM_FAULT_SIGBUS; 920 921 if (arch_needs_pgtable_deposit()) { 922 pgtable = pte_alloc_one(vma->vm_mm); 923 if (!pgtable) 924 return VM_FAULT_OOM; 925 } 926 927 track_pfn_insert(vma, &pgprot, pfn); 928 929 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 930 return VM_FAULT_NOPAGE; 931 } 932 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot); 933 934 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 935 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 936 { 937 if (likely(vma->vm_flags & VM_WRITE)) 938 pud = pud_mkwrite(pud); 939 return pud; 940 } 941 942 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 943 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) 944 { 945 struct mm_struct *mm = vma->vm_mm; 946 pud_t entry; 947 spinlock_t *ptl; 948 949 ptl = pud_lock(mm, pud); 950 if (!pud_none(*pud)) { 951 if (write) { 952 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 953 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 954 goto out_unlock; 955 } 956 entry = pud_mkyoung(*pud); 957 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 958 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 959 update_mmu_cache_pud(vma, addr, pud); 960 } 961 goto out_unlock; 962 } 963 964 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 965 if (pfn_t_devmap(pfn)) 966 entry = pud_mkdevmap(entry); 967 if (write) { 968 entry = pud_mkyoung(pud_mkdirty(entry)); 969 entry = maybe_pud_mkwrite(entry, vma); 970 } 971 set_pud_at(mm, addr, pud, entry); 972 update_mmu_cache_pud(vma, addr, pud); 973 974 out_unlock: 975 spin_unlock(ptl); 976 } 977 978 /** 979 * vmf_insert_pfn_pud_prot - insert a pud size pfn 980 * @vmf: Structure describing the fault 981 * @pfn: pfn to insert 982 * @pgprot: page protection to use 983 * @write: whether it's a write fault 984 * 985 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and 986 * also consult the vmf_insert_mixed_prot() documentation when 987 * @pgprot != @vmf->vma->vm_page_prot. 988 * 989 * Return: vm_fault_t value. 990 */ 991 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn, 992 pgprot_t pgprot, bool write) 993 { 994 unsigned long addr = vmf->address & PUD_MASK; 995 struct vm_area_struct *vma = vmf->vma; 996 997 /* 998 * If we had pud_special, we could avoid all these restrictions, 999 * but we need to be consistent with PTEs and architectures that 1000 * can't support a 'special' bit. 1001 */ 1002 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 1003 !pfn_t_devmap(pfn)); 1004 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1005 (VM_PFNMAP|VM_MIXEDMAP)); 1006 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1007 1008 if (addr < vma->vm_start || addr >= vma->vm_end) 1009 return VM_FAULT_SIGBUS; 1010 1011 track_pfn_insert(vma, &pgprot, pfn); 1012 1013 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); 1014 return VM_FAULT_NOPAGE; 1015 } 1016 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot); 1017 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1018 1019 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 1020 pmd_t *pmd, bool write) 1021 { 1022 pmd_t _pmd; 1023 1024 _pmd = pmd_mkyoung(*pmd); 1025 if (write) 1026 _pmd = pmd_mkdirty(_pmd); 1027 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 1028 pmd, _pmd, write)) 1029 update_mmu_cache_pmd(vma, addr, pmd); 1030 } 1031 1032 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 1033 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 1034 { 1035 unsigned long pfn = pmd_pfn(*pmd); 1036 struct mm_struct *mm = vma->vm_mm; 1037 struct page *page; 1038 int ret; 1039 1040 assert_spin_locked(pmd_lockptr(mm, pmd)); 1041 1042 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1043 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1044 (FOLL_PIN | FOLL_GET))) 1045 return NULL; 1046 1047 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 1048 return NULL; 1049 1050 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 1051 /* pass */; 1052 else 1053 return NULL; 1054 1055 if (flags & FOLL_TOUCH) 1056 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1057 1058 /* 1059 * device mapped pages can only be returned if the 1060 * caller will manage the page reference count. 1061 */ 1062 if (!(flags & (FOLL_GET | FOLL_PIN))) 1063 return ERR_PTR(-EEXIST); 1064 1065 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 1066 *pgmap = get_dev_pagemap(pfn, *pgmap); 1067 if (!*pgmap) 1068 return ERR_PTR(-EFAULT); 1069 page = pfn_to_page(pfn); 1070 ret = try_grab_page(page, flags); 1071 if (ret) 1072 page = ERR_PTR(ret); 1073 1074 return page; 1075 } 1076 1077 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1078 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1079 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) 1080 { 1081 spinlock_t *dst_ptl, *src_ptl; 1082 struct page *src_page; 1083 pmd_t pmd; 1084 pgtable_t pgtable = NULL; 1085 int ret = -ENOMEM; 1086 1087 /* Skip if can be re-fill on fault */ 1088 if (!vma_is_anonymous(dst_vma)) 1089 return 0; 1090 1091 pgtable = pte_alloc_one(dst_mm); 1092 if (unlikely(!pgtable)) 1093 goto out; 1094 1095 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1096 src_ptl = pmd_lockptr(src_mm, src_pmd); 1097 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1098 1099 ret = -EAGAIN; 1100 pmd = *src_pmd; 1101 1102 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1103 if (unlikely(is_swap_pmd(pmd))) { 1104 swp_entry_t entry = pmd_to_swp_entry(pmd); 1105 1106 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1107 if (!is_readable_migration_entry(entry)) { 1108 entry = make_readable_migration_entry( 1109 swp_offset(entry)); 1110 pmd = swp_entry_to_pmd(entry); 1111 if (pmd_swp_soft_dirty(*src_pmd)) 1112 pmd = pmd_swp_mksoft_dirty(pmd); 1113 if (pmd_swp_uffd_wp(*src_pmd)) 1114 pmd = pmd_swp_mkuffd_wp(pmd); 1115 set_pmd_at(src_mm, addr, src_pmd, pmd); 1116 } 1117 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1118 mm_inc_nr_ptes(dst_mm); 1119 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1120 if (!userfaultfd_wp(dst_vma)) 1121 pmd = pmd_swp_clear_uffd_wp(pmd); 1122 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1123 ret = 0; 1124 goto out_unlock; 1125 } 1126 #endif 1127 1128 if (unlikely(!pmd_trans_huge(pmd))) { 1129 pte_free(dst_mm, pgtable); 1130 goto out_unlock; 1131 } 1132 /* 1133 * When page table lock is held, the huge zero pmd should not be 1134 * under splitting since we don't split the page itself, only pmd to 1135 * a page table. 1136 */ 1137 if (is_huge_zero_pmd(pmd)) { 1138 /* 1139 * get_huge_zero_page() will never allocate a new page here, 1140 * since we already have a zero page to copy. It just takes a 1141 * reference. 1142 */ 1143 mm_get_huge_zero_page(dst_mm); 1144 goto out_zero_page; 1145 } 1146 1147 src_page = pmd_page(pmd); 1148 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1149 1150 get_page(src_page); 1151 if (unlikely(page_try_dup_anon_rmap(src_page, true, src_vma))) { 1152 /* Page maybe pinned: split and retry the fault on PTEs. */ 1153 put_page(src_page); 1154 pte_free(dst_mm, pgtable); 1155 spin_unlock(src_ptl); 1156 spin_unlock(dst_ptl); 1157 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); 1158 return -EAGAIN; 1159 } 1160 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1161 out_zero_page: 1162 mm_inc_nr_ptes(dst_mm); 1163 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1164 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1165 if (!userfaultfd_wp(dst_vma)) 1166 pmd = pmd_clear_uffd_wp(pmd); 1167 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1168 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1169 1170 ret = 0; 1171 out_unlock: 1172 spin_unlock(src_ptl); 1173 spin_unlock(dst_ptl); 1174 out: 1175 return ret; 1176 } 1177 1178 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1179 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1180 pud_t *pud, bool write) 1181 { 1182 pud_t _pud; 1183 1184 _pud = pud_mkyoung(*pud); 1185 if (write) 1186 _pud = pud_mkdirty(_pud); 1187 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1188 pud, _pud, write)) 1189 update_mmu_cache_pud(vma, addr, pud); 1190 } 1191 1192 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1193 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1194 { 1195 unsigned long pfn = pud_pfn(*pud); 1196 struct mm_struct *mm = vma->vm_mm; 1197 struct page *page; 1198 int ret; 1199 1200 assert_spin_locked(pud_lockptr(mm, pud)); 1201 1202 if (flags & FOLL_WRITE && !pud_write(*pud)) 1203 return NULL; 1204 1205 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1206 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1207 (FOLL_PIN | FOLL_GET))) 1208 return NULL; 1209 1210 if (pud_present(*pud) && pud_devmap(*pud)) 1211 /* pass */; 1212 else 1213 return NULL; 1214 1215 if (flags & FOLL_TOUCH) 1216 touch_pud(vma, addr, pud, flags & FOLL_WRITE); 1217 1218 /* 1219 * device mapped pages can only be returned if the 1220 * caller will manage the page reference count. 1221 * 1222 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here: 1223 */ 1224 if (!(flags & (FOLL_GET | FOLL_PIN))) 1225 return ERR_PTR(-EEXIST); 1226 1227 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1228 *pgmap = get_dev_pagemap(pfn, *pgmap); 1229 if (!*pgmap) 1230 return ERR_PTR(-EFAULT); 1231 page = pfn_to_page(pfn); 1232 1233 ret = try_grab_page(page, flags); 1234 if (ret) 1235 page = ERR_PTR(ret); 1236 1237 return page; 1238 } 1239 1240 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1241 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1242 struct vm_area_struct *vma) 1243 { 1244 spinlock_t *dst_ptl, *src_ptl; 1245 pud_t pud; 1246 int ret; 1247 1248 dst_ptl = pud_lock(dst_mm, dst_pud); 1249 src_ptl = pud_lockptr(src_mm, src_pud); 1250 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1251 1252 ret = -EAGAIN; 1253 pud = *src_pud; 1254 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1255 goto out_unlock; 1256 1257 /* 1258 * When page table lock is held, the huge zero pud should not be 1259 * under splitting since we don't split the page itself, only pud to 1260 * a page table. 1261 */ 1262 if (is_huge_zero_pud(pud)) { 1263 /* No huge zero pud yet */ 1264 } 1265 1266 /* 1267 * TODO: once we support anonymous pages, use page_try_dup_anon_rmap() 1268 * and split if duplicating fails. 1269 */ 1270 pudp_set_wrprotect(src_mm, addr, src_pud); 1271 pud = pud_mkold(pud_wrprotect(pud)); 1272 set_pud_at(dst_mm, addr, dst_pud, pud); 1273 1274 ret = 0; 1275 out_unlock: 1276 spin_unlock(src_ptl); 1277 spin_unlock(dst_ptl); 1278 return ret; 1279 } 1280 1281 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1282 { 1283 bool write = vmf->flags & FAULT_FLAG_WRITE; 1284 1285 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1286 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1287 goto unlock; 1288 1289 touch_pud(vmf->vma, vmf->address, vmf->pud, write); 1290 unlock: 1291 spin_unlock(vmf->ptl); 1292 } 1293 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1294 1295 void huge_pmd_set_accessed(struct vm_fault *vmf) 1296 { 1297 bool write = vmf->flags & FAULT_FLAG_WRITE; 1298 1299 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1300 if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd))) 1301 goto unlock; 1302 1303 touch_pmd(vmf->vma, vmf->address, vmf->pmd, write); 1304 1305 unlock: 1306 spin_unlock(vmf->ptl); 1307 } 1308 1309 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) 1310 { 1311 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; 1312 struct vm_area_struct *vma = vmf->vma; 1313 struct folio *folio; 1314 struct page *page; 1315 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1316 pmd_t orig_pmd = vmf->orig_pmd; 1317 1318 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1319 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1320 1321 if (is_huge_zero_pmd(orig_pmd)) 1322 goto fallback; 1323 1324 spin_lock(vmf->ptl); 1325 1326 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1327 spin_unlock(vmf->ptl); 1328 return 0; 1329 } 1330 1331 page = pmd_page(orig_pmd); 1332 folio = page_folio(page); 1333 VM_BUG_ON_PAGE(!PageHead(page), page); 1334 1335 /* Early check when only holding the PT lock. */ 1336 if (PageAnonExclusive(page)) 1337 goto reuse; 1338 1339 if (!folio_trylock(folio)) { 1340 folio_get(folio); 1341 spin_unlock(vmf->ptl); 1342 folio_lock(folio); 1343 spin_lock(vmf->ptl); 1344 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1345 spin_unlock(vmf->ptl); 1346 folio_unlock(folio); 1347 folio_put(folio); 1348 return 0; 1349 } 1350 folio_put(folio); 1351 } 1352 1353 /* Recheck after temporarily dropping the PT lock. */ 1354 if (PageAnonExclusive(page)) { 1355 folio_unlock(folio); 1356 goto reuse; 1357 } 1358 1359 /* 1360 * See do_wp_page(): we can only reuse the folio exclusively if 1361 * there are no additional references. Note that we always drain 1362 * the LRU pagevecs immediately after adding a THP. 1363 */ 1364 if (folio_ref_count(folio) > 1365 1 + folio_test_swapcache(folio) * folio_nr_pages(folio)) 1366 goto unlock_fallback; 1367 if (folio_test_swapcache(folio)) 1368 folio_free_swap(folio); 1369 if (folio_ref_count(folio) == 1) { 1370 pmd_t entry; 1371 1372 page_move_anon_rmap(page, vma); 1373 folio_unlock(folio); 1374 reuse: 1375 if (unlikely(unshare)) { 1376 spin_unlock(vmf->ptl); 1377 return 0; 1378 } 1379 entry = pmd_mkyoung(orig_pmd); 1380 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1381 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1382 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1383 spin_unlock(vmf->ptl); 1384 return 0; 1385 } 1386 1387 unlock_fallback: 1388 folio_unlock(folio); 1389 spin_unlock(vmf->ptl); 1390 fallback: 1391 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1392 return VM_FAULT_FALLBACK; 1393 } 1394 1395 static inline bool can_change_pmd_writable(struct vm_area_struct *vma, 1396 unsigned long addr, pmd_t pmd) 1397 { 1398 struct page *page; 1399 1400 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) 1401 return false; 1402 1403 /* Don't touch entries that are not even readable (NUMA hinting). */ 1404 if (pmd_protnone(pmd)) 1405 return false; 1406 1407 /* Do we need write faults for softdirty tracking? */ 1408 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) 1409 return false; 1410 1411 /* Do we need write faults for uffd-wp tracking? */ 1412 if (userfaultfd_huge_pmd_wp(vma, pmd)) 1413 return false; 1414 1415 if (!(vma->vm_flags & VM_SHARED)) { 1416 /* See can_change_pte_writable(). */ 1417 page = vm_normal_page_pmd(vma, addr, pmd); 1418 return page && PageAnon(page) && PageAnonExclusive(page); 1419 } 1420 1421 /* See can_change_pte_writable(). */ 1422 return pmd_dirty(pmd); 1423 } 1424 1425 /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */ 1426 static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page, 1427 struct vm_area_struct *vma, 1428 unsigned int flags) 1429 { 1430 /* If the pmd is writable, we can write to the page. */ 1431 if (pmd_write(pmd)) 1432 return true; 1433 1434 /* Maybe FOLL_FORCE is set to override it? */ 1435 if (!(flags & FOLL_FORCE)) 1436 return false; 1437 1438 /* But FOLL_FORCE has no effect on shared mappings */ 1439 if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED)) 1440 return false; 1441 1442 /* ... or read-only private ones */ 1443 if (!(vma->vm_flags & VM_MAYWRITE)) 1444 return false; 1445 1446 /* ... or already writable ones that just need to take a write fault */ 1447 if (vma->vm_flags & VM_WRITE) 1448 return false; 1449 1450 /* 1451 * See can_change_pte_writable(): we broke COW and could map the page 1452 * writable if we have an exclusive anonymous page ... 1453 */ 1454 if (!page || !PageAnon(page) || !PageAnonExclusive(page)) 1455 return false; 1456 1457 /* ... and a write-fault isn't required for other reasons. */ 1458 if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd)) 1459 return false; 1460 return !userfaultfd_huge_pmd_wp(vma, pmd); 1461 } 1462 1463 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1464 unsigned long addr, 1465 pmd_t *pmd, 1466 unsigned int flags) 1467 { 1468 struct mm_struct *mm = vma->vm_mm; 1469 struct page *page; 1470 int ret; 1471 1472 assert_spin_locked(pmd_lockptr(mm, pmd)); 1473 1474 page = pmd_page(*pmd); 1475 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1476 1477 if ((flags & FOLL_WRITE) && 1478 !can_follow_write_pmd(*pmd, page, vma, flags)) 1479 return NULL; 1480 1481 /* Avoid dumping huge zero page */ 1482 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1483 return ERR_PTR(-EFAULT); 1484 1485 /* Full NUMA hinting faults to serialise migration in fault paths */ 1486 if (pmd_protnone(*pmd) && !gup_can_follow_protnone(flags)) 1487 return NULL; 1488 1489 if (!pmd_write(*pmd) && gup_must_unshare(vma, flags, page)) 1490 return ERR_PTR(-EMLINK); 1491 1492 VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) && 1493 !PageAnonExclusive(page), page); 1494 1495 ret = try_grab_page(page, flags); 1496 if (ret) 1497 return ERR_PTR(ret); 1498 1499 if (flags & FOLL_TOUCH) 1500 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE); 1501 1502 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1503 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1504 1505 return page; 1506 } 1507 1508 /* NUMA hinting page fault entry point for trans huge pmds */ 1509 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) 1510 { 1511 struct vm_area_struct *vma = vmf->vma; 1512 pmd_t oldpmd = vmf->orig_pmd; 1513 pmd_t pmd; 1514 struct page *page; 1515 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1516 int page_nid = NUMA_NO_NODE; 1517 int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK); 1518 bool migrated = false, writable = false; 1519 int flags = 0; 1520 1521 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1522 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1523 spin_unlock(vmf->ptl); 1524 goto out; 1525 } 1526 1527 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1528 1529 /* 1530 * Detect now whether the PMD could be writable; this information 1531 * is only valid while holding the PT lock. 1532 */ 1533 writable = pmd_write(pmd); 1534 if (!writable && vma_wants_manual_pte_write_upgrade(vma) && 1535 can_change_pmd_writable(vma, vmf->address, pmd)) 1536 writable = true; 1537 1538 page = vm_normal_page_pmd(vma, haddr, pmd); 1539 if (!page) 1540 goto out_map; 1541 1542 /* See similar comment in do_numa_page for explanation */ 1543 if (!writable) 1544 flags |= TNF_NO_GROUP; 1545 1546 page_nid = page_to_nid(page); 1547 /* 1548 * For memory tiering mode, cpupid of slow memory page is used 1549 * to record page access time. So use default value. 1550 */ 1551 if (node_is_toptier(page_nid)) 1552 last_cpupid = page_cpupid_last(page); 1553 target_nid = numa_migrate_prep(page, vma, haddr, page_nid, 1554 &flags); 1555 1556 if (target_nid == NUMA_NO_NODE) { 1557 put_page(page); 1558 goto out_map; 1559 } 1560 1561 spin_unlock(vmf->ptl); 1562 writable = false; 1563 1564 migrated = migrate_misplaced_page(page, vma, target_nid); 1565 if (migrated) { 1566 flags |= TNF_MIGRATED; 1567 page_nid = target_nid; 1568 } else { 1569 flags |= TNF_MIGRATE_FAIL; 1570 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1571 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1572 spin_unlock(vmf->ptl); 1573 goto out; 1574 } 1575 goto out_map; 1576 } 1577 1578 out: 1579 if (page_nid != NUMA_NO_NODE) 1580 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1581 flags); 1582 1583 return 0; 1584 1585 out_map: 1586 /* Restore the PMD */ 1587 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1588 pmd = pmd_mkyoung(pmd); 1589 if (writable) 1590 pmd = pmd_mkwrite(pmd); 1591 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1592 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1593 spin_unlock(vmf->ptl); 1594 goto out; 1595 } 1596 1597 /* 1598 * Return true if we do MADV_FREE successfully on entire pmd page. 1599 * Otherwise, return false. 1600 */ 1601 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1602 pmd_t *pmd, unsigned long addr, unsigned long next) 1603 { 1604 spinlock_t *ptl; 1605 pmd_t orig_pmd; 1606 struct page *page; 1607 struct mm_struct *mm = tlb->mm; 1608 bool ret = false; 1609 1610 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1611 1612 ptl = pmd_trans_huge_lock(pmd, vma); 1613 if (!ptl) 1614 goto out_unlocked; 1615 1616 orig_pmd = *pmd; 1617 if (is_huge_zero_pmd(orig_pmd)) 1618 goto out; 1619 1620 if (unlikely(!pmd_present(orig_pmd))) { 1621 VM_BUG_ON(thp_migration_supported() && 1622 !is_pmd_migration_entry(orig_pmd)); 1623 goto out; 1624 } 1625 1626 page = pmd_page(orig_pmd); 1627 /* 1628 * If other processes are mapping this page, we couldn't discard 1629 * the page unless they all do MADV_FREE so let's skip the page. 1630 */ 1631 if (total_mapcount(page) != 1) 1632 goto out; 1633 1634 if (!trylock_page(page)) 1635 goto out; 1636 1637 /* 1638 * If user want to discard part-pages of THP, split it so MADV_FREE 1639 * will deactivate only them. 1640 */ 1641 if (next - addr != HPAGE_PMD_SIZE) { 1642 get_page(page); 1643 spin_unlock(ptl); 1644 split_huge_page(page); 1645 unlock_page(page); 1646 put_page(page); 1647 goto out_unlocked; 1648 } 1649 1650 if (PageDirty(page)) 1651 ClearPageDirty(page); 1652 unlock_page(page); 1653 1654 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1655 pmdp_invalidate(vma, addr, pmd); 1656 orig_pmd = pmd_mkold(orig_pmd); 1657 orig_pmd = pmd_mkclean(orig_pmd); 1658 1659 set_pmd_at(mm, addr, pmd, orig_pmd); 1660 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1661 } 1662 1663 mark_page_lazyfree(page); 1664 ret = true; 1665 out: 1666 spin_unlock(ptl); 1667 out_unlocked: 1668 return ret; 1669 } 1670 1671 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1672 { 1673 pgtable_t pgtable; 1674 1675 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1676 pte_free(mm, pgtable); 1677 mm_dec_nr_ptes(mm); 1678 } 1679 1680 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1681 pmd_t *pmd, unsigned long addr) 1682 { 1683 pmd_t orig_pmd; 1684 spinlock_t *ptl; 1685 1686 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1687 1688 ptl = __pmd_trans_huge_lock(pmd, vma); 1689 if (!ptl) 1690 return 0; 1691 /* 1692 * For architectures like ppc64 we look at deposited pgtable 1693 * when calling pmdp_huge_get_and_clear. So do the 1694 * pgtable_trans_huge_withdraw after finishing pmdp related 1695 * operations. 1696 */ 1697 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1698 tlb->fullmm); 1699 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1700 if (vma_is_special_huge(vma)) { 1701 if (arch_needs_pgtable_deposit()) 1702 zap_deposited_table(tlb->mm, pmd); 1703 spin_unlock(ptl); 1704 } else if (is_huge_zero_pmd(orig_pmd)) { 1705 zap_deposited_table(tlb->mm, pmd); 1706 spin_unlock(ptl); 1707 } else { 1708 struct page *page = NULL; 1709 int flush_needed = 1; 1710 1711 if (pmd_present(orig_pmd)) { 1712 page = pmd_page(orig_pmd); 1713 page_remove_rmap(page, vma, true); 1714 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1715 VM_BUG_ON_PAGE(!PageHead(page), page); 1716 } else if (thp_migration_supported()) { 1717 swp_entry_t entry; 1718 1719 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1720 entry = pmd_to_swp_entry(orig_pmd); 1721 page = pfn_swap_entry_to_page(entry); 1722 flush_needed = 0; 1723 } else 1724 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1725 1726 if (PageAnon(page)) { 1727 zap_deposited_table(tlb->mm, pmd); 1728 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1729 } else { 1730 if (arch_needs_pgtable_deposit()) 1731 zap_deposited_table(tlb->mm, pmd); 1732 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1733 } 1734 1735 spin_unlock(ptl); 1736 if (flush_needed) 1737 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1738 } 1739 return 1; 1740 } 1741 1742 #ifndef pmd_move_must_withdraw 1743 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1744 spinlock_t *old_pmd_ptl, 1745 struct vm_area_struct *vma) 1746 { 1747 /* 1748 * With split pmd lock we also need to move preallocated 1749 * PTE page table if new_pmd is on different PMD page table. 1750 * 1751 * We also don't deposit and withdraw tables for file pages. 1752 */ 1753 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1754 } 1755 #endif 1756 1757 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1758 { 1759 #ifdef CONFIG_MEM_SOFT_DIRTY 1760 if (unlikely(is_pmd_migration_entry(pmd))) 1761 pmd = pmd_swp_mksoft_dirty(pmd); 1762 else if (pmd_present(pmd)) 1763 pmd = pmd_mksoft_dirty(pmd); 1764 #endif 1765 return pmd; 1766 } 1767 1768 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1769 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1770 { 1771 spinlock_t *old_ptl, *new_ptl; 1772 pmd_t pmd; 1773 struct mm_struct *mm = vma->vm_mm; 1774 bool force_flush = false; 1775 1776 /* 1777 * The destination pmd shouldn't be established, free_pgtables() 1778 * should have release it. 1779 */ 1780 if (WARN_ON(!pmd_none(*new_pmd))) { 1781 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1782 return false; 1783 } 1784 1785 /* 1786 * We don't have to worry about the ordering of src and dst 1787 * ptlocks because exclusive mmap_lock prevents deadlock. 1788 */ 1789 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1790 if (old_ptl) { 1791 new_ptl = pmd_lockptr(mm, new_pmd); 1792 if (new_ptl != old_ptl) 1793 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1794 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1795 if (pmd_present(pmd)) 1796 force_flush = true; 1797 VM_BUG_ON(!pmd_none(*new_pmd)); 1798 1799 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1800 pgtable_t pgtable; 1801 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1802 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1803 } 1804 pmd = move_soft_dirty_pmd(pmd); 1805 set_pmd_at(mm, new_addr, new_pmd, pmd); 1806 if (force_flush) 1807 flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1808 if (new_ptl != old_ptl) 1809 spin_unlock(new_ptl); 1810 spin_unlock(old_ptl); 1811 return true; 1812 } 1813 return false; 1814 } 1815 1816 /* 1817 * Returns 1818 * - 0 if PMD could not be locked 1819 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary 1820 * or if prot_numa but THP migration is not supported 1821 * - HPAGE_PMD_NR if protections changed and TLB flush necessary 1822 */ 1823 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1824 pmd_t *pmd, unsigned long addr, pgprot_t newprot, 1825 unsigned long cp_flags) 1826 { 1827 struct mm_struct *mm = vma->vm_mm; 1828 spinlock_t *ptl; 1829 pmd_t oldpmd, entry; 1830 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1831 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1832 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1833 int ret = 1; 1834 1835 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1836 1837 if (prot_numa && !thp_migration_supported()) 1838 return 1; 1839 1840 ptl = __pmd_trans_huge_lock(pmd, vma); 1841 if (!ptl) 1842 return 0; 1843 1844 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1845 if (is_swap_pmd(*pmd)) { 1846 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1847 struct page *page = pfn_swap_entry_to_page(entry); 1848 1849 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1850 if (is_writable_migration_entry(entry)) { 1851 pmd_t newpmd; 1852 /* 1853 * A protection check is difficult so 1854 * just be safe and disable write 1855 */ 1856 if (PageAnon(page)) 1857 entry = make_readable_exclusive_migration_entry(swp_offset(entry)); 1858 else 1859 entry = make_readable_migration_entry(swp_offset(entry)); 1860 newpmd = swp_entry_to_pmd(entry); 1861 if (pmd_swp_soft_dirty(*pmd)) 1862 newpmd = pmd_swp_mksoft_dirty(newpmd); 1863 if (pmd_swp_uffd_wp(*pmd)) 1864 newpmd = pmd_swp_mkuffd_wp(newpmd); 1865 set_pmd_at(mm, addr, pmd, newpmd); 1866 } 1867 goto unlock; 1868 } 1869 #endif 1870 1871 if (prot_numa) { 1872 struct page *page; 1873 bool toptier; 1874 /* 1875 * Avoid trapping faults against the zero page. The read-only 1876 * data is likely to be read-cached on the local CPU and 1877 * local/remote hits to the zero page are not interesting. 1878 */ 1879 if (is_huge_zero_pmd(*pmd)) 1880 goto unlock; 1881 1882 if (pmd_protnone(*pmd)) 1883 goto unlock; 1884 1885 page = pmd_page(*pmd); 1886 toptier = node_is_toptier(page_to_nid(page)); 1887 /* 1888 * Skip scanning top tier node if normal numa 1889 * balancing is disabled 1890 */ 1891 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 1892 toptier) 1893 goto unlock; 1894 1895 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING && 1896 !toptier) 1897 xchg_page_access_time(page, jiffies_to_msecs(jiffies)); 1898 } 1899 /* 1900 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 1901 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1902 * which is also under mmap_read_lock(mm): 1903 * 1904 * CPU0: CPU1: 1905 * change_huge_pmd(prot_numa=1) 1906 * pmdp_huge_get_and_clear_notify() 1907 * madvise_dontneed() 1908 * zap_pmd_range() 1909 * pmd_trans_huge(*pmd) == 0 (without ptl) 1910 * // skip the pmd 1911 * set_pmd_at(); 1912 * // pmd is re-established 1913 * 1914 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1915 * which may break userspace. 1916 * 1917 * pmdp_invalidate_ad() is required to make sure we don't miss 1918 * dirty/young flags set by hardware. 1919 */ 1920 oldpmd = pmdp_invalidate_ad(vma, addr, pmd); 1921 1922 entry = pmd_modify(oldpmd, newprot); 1923 if (uffd_wp) { 1924 entry = pmd_wrprotect(entry); 1925 entry = pmd_mkuffd_wp(entry); 1926 } else if (uffd_wp_resolve) { 1927 /* 1928 * Leave the write bit to be handled by PF interrupt 1929 * handler, then things like COW could be properly 1930 * handled. 1931 */ 1932 entry = pmd_clear_uffd_wp(entry); 1933 } 1934 1935 /* See change_pte_range(). */ 1936 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) && 1937 can_change_pmd_writable(vma, addr, entry)) 1938 entry = pmd_mkwrite(entry); 1939 1940 ret = HPAGE_PMD_NR; 1941 set_pmd_at(mm, addr, pmd, entry); 1942 1943 if (huge_pmd_needs_flush(oldpmd, entry)) 1944 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); 1945 unlock: 1946 spin_unlock(ptl); 1947 return ret; 1948 } 1949 1950 /* 1951 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1952 * 1953 * Note that if it returns page table lock pointer, this routine returns without 1954 * unlocking page table lock. So callers must unlock it. 1955 */ 1956 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1957 { 1958 spinlock_t *ptl; 1959 ptl = pmd_lock(vma->vm_mm, pmd); 1960 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 1961 pmd_devmap(*pmd))) 1962 return ptl; 1963 spin_unlock(ptl); 1964 return NULL; 1965 } 1966 1967 /* 1968 * Returns page table lock pointer if a given pud maps a thp, NULL otherwise. 1969 * 1970 * Note that if it returns page table lock pointer, this routine returns without 1971 * unlocking page table lock. So callers must unlock it. 1972 */ 1973 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 1974 { 1975 spinlock_t *ptl; 1976 1977 ptl = pud_lock(vma->vm_mm, pud); 1978 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 1979 return ptl; 1980 spin_unlock(ptl); 1981 return NULL; 1982 } 1983 1984 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1985 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 1986 pud_t *pud, unsigned long addr) 1987 { 1988 spinlock_t *ptl; 1989 1990 ptl = __pud_trans_huge_lock(pud, vma); 1991 if (!ptl) 1992 return 0; 1993 1994 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 1995 tlb_remove_pud_tlb_entry(tlb, pud, addr); 1996 if (vma_is_special_huge(vma)) { 1997 spin_unlock(ptl); 1998 /* No zero page support yet */ 1999 } else { 2000 /* No support for anonymous PUD pages yet */ 2001 BUG(); 2002 } 2003 return 1; 2004 } 2005 2006 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 2007 unsigned long haddr) 2008 { 2009 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 2010 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2011 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 2012 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 2013 2014 count_vm_event(THP_SPLIT_PUD); 2015 2016 pudp_huge_clear_flush_notify(vma, haddr, pud); 2017 } 2018 2019 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 2020 unsigned long address) 2021 { 2022 spinlock_t *ptl; 2023 struct mmu_notifier_range range; 2024 2025 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2026 address & HPAGE_PUD_MASK, 2027 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 2028 mmu_notifier_invalidate_range_start(&range); 2029 ptl = pud_lock(vma->vm_mm, pud); 2030 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 2031 goto out; 2032 __split_huge_pud_locked(vma, pud, range.start); 2033 2034 out: 2035 spin_unlock(ptl); 2036 /* 2037 * No need to double call mmu_notifier->invalidate_range() callback as 2038 * the above pudp_huge_clear_flush_notify() did already call it. 2039 */ 2040 mmu_notifier_invalidate_range_only_end(&range); 2041 } 2042 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 2043 2044 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2045 unsigned long haddr, pmd_t *pmd) 2046 { 2047 struct mm_struct *mm = vma->vm_mm; 2048 pgtable_t pgtable; 2049 pmd_t _pmd; 2050 int i; 2051 2052 /* 2053 * Leave pmd empty until pte is filled note that it is fine to delay 2054 * notification until mmu_notifier_invalidate_range_end() as we are 2055 * replacing a zero pmd write protected page with a zero pte write 2056 * protected page. 2057 * 2058 * See Documentation/mm/mmu_notifier.rst 2059 */ 2060 pmdp_huge_clear_flush(vma, haddr, pmd); 2061 2062 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2063 pmd_populate(mm, &_pmd, pgtable); 2064 2065 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 2066 pte_t *pte, entry; 2067 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 2068 entry = pte_mkspecial(entry); 2069 pte = pte_offset_map(&_pmd, haddr); 2070 VM_BUG_ON(!pte_none(*pte)); 2071 set_pte_at(mm, haddr, pte, entry); 2072 pte_unmap(pte); 2073 } 2074 smp_wmb(); /* make pte visible before pmd */ 2075 pmd_populate(mm, pmd, pgtable); 2076 } 2077 2078 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2079 unsigned long haddr, bool freeze) 2080 { 2081 struct mm_struct *mm = vma->vm_mm; 2082 struct page *page; 2083 pgtable_t pgtable; 2084 pmd_t old_pmd, _pmd; 2085 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 2086 bool anon_exclusive = false, dirty = false; 2087 unsigned long addr; 2088 int i; 2089 2090 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2091 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2092 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2093 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2094 && !pmd_devmap(*pmd)); 2095 2096 count_vm_event(THP_SPLIT_PMD); 2097 2098 if (!vma_is_anonymous(vma)) { 2099 old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 2100 /* 2101 * We are going to unmap this huge page. So 2102 * just go ahead and zap it 2103 */ 2104 if (arch_needs_pgtable_deposit()) 2105 zap_deposited_table(mm, pmd); 2106 if (vma_is_special_huge(vma)) 2107 return; 2108 if (unlikely(is_pmd_migration_entry(old_pmd))) { 2109 swp_entry_t entry; 2110 2111 entry = pmd_to_swp_entry(old_pmd); 2112 page = pfn_swap_entry_to_page(entry); 2113 } else { 2114 page = pmd_page(old_pmd); 2115 if (!PageDirty(page) && pmd_dirty(old_pmd)) 2116 set_page_dirty(page); 2117 if (!PageReferenced(page) && pmd_young(old_pmd)) 2118 SetPageReferenced(page); 2119 page_remove_rmap(page, vma, true); 2120 put_page(page); 2121 } 2122 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2123 return; 2124 } 2125 2126 if (is_huge_zero_pmd(*pmd)) { 2127 /* 2128 * FIXME: Do we want to invalidate secondary mmu by calling 2129 * mmu_notifier_invalidate_range() see comments below inside 2130 * __split_huge_pmd() ? 2131 * 2132 * We are going from a zero huge page write protected to zero 2133 * small page also write protected so it does not seems useful 2134 * to invalidate secondary mmu at this time. 2135 */ 2136 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2137 } 2138 2139 /* 2140 * Up to this point the pmd is present and huge and userland has the 2141 * whole access to the hugepage during the split (which happens in 2142 * place). If we overwrite the pmd with the not-huge version pointing 2143 * to the pte here (which of course we could if all CPUs were bug 2144 * free), userland could trigger a small page size TLB miss on the 2145 * small sized TLB while the hugepage TLB entry is still established in 2146 * the huge TLB. Some CPU doesn't like that. 2147 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2148 * 383 on page 105. Intel should be safe but is also warns that it's 2149 * only safe if the permission and cache attributes of the two entries 2150 * loaded in the two TLB is identical (which should be the case here). 2151 * But it is generally safer to never allow small and huge TLB entries 2152 * for the same virtual address to be loaded simultaneously. So instead 2153 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2154 * current pmd notpresent (atomically because here the pmd_trans_huge 2155 * must remain set at all times on the pmd until the split is complete 2156 * for this pmd), then we flush the SMP TLB and finally we write the 2157 * non-huge version of the pmd entry with pmd_populate. 2158 */ 2159 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2160 2161 pmd_migration = is_pmd_migration_entry(old_pmd); 2162 if (unlikely(pmd_migration)) { 2163 swp_entry_t entry; 2164 2165 entry = pmd_to_swp_entry(old_pmd); 2166 page = pfn_swap_entry_to_page(entry); 2167 write = is_writable_migration_entry(entry); 2168 if (PageAnon(page)) 2169 anon_exclusive = is_readable_exclusive_migration_entry(entry); 2170 young = is_migration_entry_young(entry); 2171 dirty = is_migration_entry_dirty(entry); 2172 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2173 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2174 } else { 2175 page = pmd_page(old_pmd); 2176 if (pmd_dirty(old_pmd)) { 2177 dirty = true; 2178 SetPageDirty(page); 2179 } 2180 write = pmd_write(old_pmd); 2181 young = pmd_young(old_pmd); 2182 soft_dirty = pmd_soft_dirty(old_pmd); 2183 uffd_wp = pmd_uffd_wp(old_pmd); 2184 2185 VM_BUG_ON_PAGE(!page_count(page), page); 2186 2187 /* 2188 * Without "freeze", we'll simply split the PMD, propagating the 2189 * PageAnonExclusive() flag for each PTE by setting it for 2190 * each subpage -- no need to (temporarily) clear. 2191 * 2192 * With "freeze" we want to replace mapped pages by 2193 * migration entries right away. This is only possible if we 2194 * managed to clear PageAnonExclusive() -- see 2195 * set_pmd_migration_entry(). 2196 * 2197 * In case we cannot clear PageAnonExclusive(), split the PMD 2198 * only and let try_to_migrate_one() fail later. 2199 * 2200 * See page_try_share_anon_rmap(): invalidate PMD first. 2201 */ 2202 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 2203 if (freeze && anon_exclusive && page_try_share_anon_rmap(page)) 2204 freeze = false; 2205 if (!freeze) 2206 page_ref_add(page, HPAGE_PMD_NR - 1); 2207 } 2208 2209 /* 2210 * Withdraw the table only after we mark the pmd entry invalid. 2211 * This's critical for some architectures (Power). 2212 */ 2213 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2214 pmd_populate(mm, &_pmd, pgtable); 2215 2216 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2217 pte_t entry, *pte; 2218 /* 2219 * Note that NUMA hinting access restrictions are not 2220 * transferred to avoid any possibility of altering 2221 * permissions across VMAs. 2222 */ 2223 if (freeze || pmd_migration) { 2224 swp_entry_t swp_entry; 2225 if (write) 2226 swp_entry = make_writable_migration_entry( 2227 page_to_pfn(page + i)); 2228 else if (anon_exclusive) 2229 swp_entry = make_readable_exclusive_migration_entry( 2230 page_to_pfn(page + i)); 2231 else 2232 swp_entry = make_readable_migration_entry( 2233 page_to_pfn(page + i)); 2234 if (young) 2235 swp_entry = make_migration_entry_young(swp_entry); 2236 if (dirty) 2237 swp_entry = make_migration_entry_dirty(swp_entry); 2238 entry = swp_entry_to_pte(swp_entry); 2239 if (soft_dirty) 2240 entry = pte_swp_mksoft_dirty(entry); 2241 if (uffd_wp) 2242 entry = pte_swp_mkuffd_wp(entry); 2243 } else { 2244 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2245 entry = maybe_mkwrite(entry, vma); 2246 if (anon_exclusive) 2247 SetPageAnonExclusive(page + i); 2248 if (!young) 2249 entry = pte_mkold(entry); 2250 /* NOTE: this may set soft-dirty too on some archs */ 2251 if (dirty) 2252 entry = pte_mkdirty(entry); 2253 /* 2254 * NOTE: this needs to happen after pte_mkdirty, 2255 * because some archs (sparc64, loongarch) could 2256 * set hw write bit when mkdirty. 2257 */ 2258 if (!write) 2259 entry = pte_wrprotect(entry); 2260 if (soft_dirty) 2261 entry = pte_mksoft_dirty(entry); 2262 if (uffd_wp) 2263 entry = pte_mkuffd_wp(entry); 2264 page_add_anon_rmap(page + i, vma, addr, false); 2265 } 2266 pte = pte_offset_map(&_pmd, addr); 2267 BUG_ON(!pte_none(*pte)); 2268 set_pte_at(mm, addr, pte, entry); 2269 pte_unmap(pte); 2270 } 2271 2272 if (!pmd_migration) 2273 page_remove_rmap(page, vma, true); 2274 if (freeze) 2275 put_page(page); 2276 2277 smp_wmb(); /* make pte visible before pmd */ 2278 pmd_populate(mm, pmd, pgtable); 2279 } 2280 2281 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2282 unsigned long address, bool freeze, struct folio *folio) 2283 { 2284 spinlock_t *ptl; 2285 struct mmu_notifier_range range; 2286 2287 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2288 address & HPAGE_PMD_MASK, 2289 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2290 mmu_notifier_invalidate_range_start(&range); 2291 ptl = pmd_lock(vma->vm_mm, pmd); 2292 2293 /* 2294 * If caller asks to setup a migration entry, we need a folio to check 2295 * pmd against. Otherwise we can end up replacing wrong folio. 2296 */ 2297 VM_BUG_ON(freeze && !folio); 2298 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); 2299 2300 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || 2301 is_pmd_migration_entry(*pmd)) { 2302 /* 2303 * It's safe to call pmd_page when folio is set because it's 2304 * guaranteed that pmd is present. 2305 */ 2306 if (folio && folio != page_folio(pmd_page(*pmd))) 2307 goto out; 2308 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2309 } 2310 2311 out: 2312 spin_unlock(ptl); 2313 /* 2314 * No need to double call mmu_notifier->invalidate_range() callback. 2315 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2316 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2317 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2318 * fault will trigger a flush_notify before pointing to a new page 2319 * (it is fine if the secondary mmu keeps pointing to the old zero 2320 * page in the meantime) 2321 * 3) Split a huge pmd into pte pointing to the same page. No need 2322 * to invalidate secondary tlb entry they are all still valid. 2323 * any further changes to individual pte will notify. So no need 2324 * to call mmu_notifier->invalidate_range() 2325 */ 2326 mmu_notifier_invalidate_range_only_end(&range); 2327 } 2328 2329 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2330 bool freeze, struct folio *folio) 2331 { 2332 pmd_t *pmd = mm_find_pmd(vma->vm_mm, address); 2333 2334 if (!pmd) 2335 return; 2336 2337 __split_huge_pmd(vma, pmd, address, freeze, folio); 2338 } 2339 2340 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) 2341 { 2342 /* 2343 * If the new address isn't hpage aligned and it could previously 2344 * contain an hugepage: check if we need to split an huge pmd. 2345 */ 2346 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && 2347 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), 2348 ALIGN(address, HPAGE_PMD_SIZE))) 2349 split_huge_pmd_address(vma, address, false, NULL); 2350 } 2351 2352 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2353 unsigned long start, 2354 unsigned long end, 2355 long adjust_next) 2356 { 2357 /* Check if we need to split start first. */ 2358 split_huge_pmd_if_needed(vma, start); 2359 2360 /* Check if we need to split end next. */ 2361 split_huge_pmd_if_needed(vma, end); 2362 2363 /* 2364 * If we're also updating the next vma vm_start, 2365 * check if we need to split it. 2366 */ 2367 if (adjust_next > 0) { 2368 struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end); 2369 unsigned long nstart = next->vm_start; 2370 nstart += adjust_next; 2371 split_huge_pmd_if_needed(next, nstart); 2372 } 2373 } 2374 2375 static void unmap_folio(struct folio *folio) 2376 { 2377 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | 2378 TTU_SYNC; 2379 2380 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 2381 2382 /* 2383 * Anon pages need migration entries to preserve them, but file 2384 * pages can simply be left unmapped, then faulted back on demand. 2385 * If that is ever changed (perhaps for mlock), update remap_page(). 2386 */ 2387 if (folio_test_anon(folio)) 2388 try_to_migrate(folio, ttu_flags); 2389 else 2390 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); 2391 } 2392 2393 static void remap_page(struct folio *folio, unsigned long nr) 2394 { 2395 int i = 0; 2396 2397 /* If unmap_folio() uses try_to_migrate() on file, remove this check */ 2398 if (!folio_test_anon(folio)) 2399 return; 2400 for (;;) { 2401 remove_migration_ptes(folio, folio, true); 2402 i += folio_nr_pages(folio); 2403 if (i >= nr) 2404 break; 2405 folio = folio_next(folio); 2406 } 2407 } 2408 2409 static void lru_add_page_tail(struct page *head, struct page *tail, 2410 struct lruvec *lruvec, struct list_head *list) 2411 { 2412 VM_BUG_ON_PAGE(!PageHead(head), head); 2413 VM_BUG_ON_PAGE(PageCompound(tail), head); 2414 VM_BUG_ON_PAGE(PageLRU(tail), head); 2415 lockdep_assert_held(&lruvec->lru_lock); 2416 2417 if (list) { 2418 /* page reclaim is reclaiming a huge page */ 2419 VM_WARN_ON(PageLRU(head)); 2420 get_page(tail); 2421 list_add_tail(&tail->lru, list); 2422 } else { 2423 /* head is still on lru (and we have it frozen) */ 2424 VM_WARN_ON(!PageLRU(head)); 2425 if (PageUnevictable(tail)) 2426 tail->mlock_count = 0; 2427 else 2428 list_add_tail(&tail->lru, &head->lru); 2429 SetPageLRU(tail); 2430 } 2431 } 2432 2433 static void __split_huge_page_tail(struct page *head, int tail, 2434 struct lruvec *lruvec, struct list_head *list) 2435 { 2436 struct page *page_tail = head + tail; 2437 2438 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2439 2440 /* 2441 * Clone page flags before unfreezing refcount. 2442 * 2443 * After successful get_page_unless_zero() might follow flags change, 2444 * for example lock_page() which set PG_waiters. 2445 * 2446 * Note that for mapped sub-pages of an anonymous THP, 2447 * PG_anon_exclusive has been cleared in unmap_folio() and is stored in 2448 * the migration entry instead from where remap_page() will restore it. 2449 * We can still have PG_anon_exclusive set on effectively unmapped and 2450 * unreferenced sub-pages of an anonymous THP: we can simply drop 2451 * PG_anon_exclusive (-> PG_mappedtodisk) for these here. 2452 */ 2453 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2454 page_tail->flags |= (head->flags & 2455 ((1L << PG_referenced) | 2456 (1L << PG_swapbacked) | 2457 (1L << PG_swapcache) | 2458 (1L << PG_mlocked) | 2459 (1L << PG_uptodate) | 2460 (1L << PG_active) | 2461 (1L << PG_workingset) | 2462 (1L << PG_locked) | 2463 (1L << PG_unevictable) | 2464 #ifdef CONFIG_ARCH_USES_PG_ARCH_X 2465 (1L << PG_arch_2) | 2466 (1L << PG_arch_3) | 2467 #endif 2468 (1L << PG_dirty) | 2469 LRU_GEN_MASK | LRU_REFS_MASK)); 2470 2471 /* ->mapping in first and second tail page is replaced by other uses */ 2472 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2473 page_tail); 2474 page_tail->mapping = head->mapping; 2475 page_tail->index = head->index + tail; 2476 2477 /* 2478 * page->private should not be set in tail pages with the exception 2479 * of swap cache pages that store the swp_entry_t in tail pages. 2480 * Fix up and warn once if private is unexpectedly set. 2481 * 2482 * What of 32-bit systems, on which head[1].compound_pincount overlays 2483 * head[1].private? No problem: THP_SWAP is not enabled on 32-bit, and 2484 * compound_pincount must be 0 for folio_ref_freeze() to have succeeded. 2485 */ 2486 if (!folio_test_swapcache(page_folio(head))) { 2487 VM_WARN_ON_ONCE_PAGE(page_tail->private != 0, page_tail); 2488 page_tail->private = 0; 2489 } 2490 2491 /* Page flags must be visible before we make the page non-compound. */ 2492 smp_wmb(); 2493 2494 /* 2495 * Clear PageTail before unfreezing page refcount. 2496 * 2497 * After successful get_page_unless_zero() might follow put_page() 2498 * which needs correct compound_head(). 2499 */ 2500 clear_compound_head(page_tail); 2501 2502 /* Finally unfreeze refcount. Additional reference from page cache. */ 2503 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2504 PageSwapCache(head))); 2505 2506 if (page_is_young(head)) 2507 set_page_young(page_tail); 2508 if (page_is_idle(head)) 2509 set_page_idle(page_tail); 2510 2511 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2512 2513 /* 2514 * always add to the tail because some iterators expect new 2515 * pages to show after the currently processed elements - e.g. 2516 * migrate_pages 2517 */ 2518 lru_add_page_tail(head, page_tail, lruvec, list); 2519 } 2520 2521 static void __split_huge_page(struct page *page, struct list_head *list, 2522 pgoff_t end) 2523 { 2524 struct folio *folio = page_folio(page); 2525 struct page *head = &folio->page; 2526 struct lruvec *lruvec; 2527 struct address_space *swap_cache = NULL; 2528 unsigned long offset = 0; 2529 unsigned int nr = thp_nr_pages(head); 2530 int i; 2531 2532 /* complete memcg works before add pages to LRU */ 2533 split_page_memcg(head, nr); 2534 2535 if (PageAnon(head) && PageSwapCache(head)) { 2536 swp_entry_t entry = { .val = page_private(head) }; 2537 2538 offset = swp_offset(entry); 2539 swap_cache = swap_address_space(entry); 2540 xa_lock(&swap_cache->i_pages); 2541 } 2542 2543 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ 2544 lruvec = folio_lruvec_lock(folio); 2545 2546 ClearPageHasHWPoisoned(head); 2547 2548 for (i = nr - 1; i >= 1; i--) { 2549 __split_huge_page_tail(head, i, lruvec, list); 2550 /* Some pages can be beyond EOF: drop them from page cache */ 2551 if (head[i].index >= end) { 2552 struct folio *tail = page_folio(head + i); 2553 2554 if (shmem_mapping(head->mapping)) 2555 shmem_uncharge(head->mapping->host, 1); 2556 else if (folio_test_clear_dirty(tail)) 2557 folio_account_cleaned(tail, 2558 inode_to_wb(folio->mapping->host)); 2559 __filemap_remove_folio(tail, NULL); 2560 folio_put(tail); 2561 } else if (!PageAnon(page)) { 2562 __xa_store(&head->mapping->i_pages, head[i].index, 2563 head + i, 0); 2564 } else if (swap_cache) { 2565 __xa_store(&swap_cache->i_pages, offset + i, 2566 head + i, 0); 2567 } 2568 } 2569 2570 ClearPageCompound(head); 2571 unlock_page_lruvec(lruvec); 2572 /* Caller disabled irqs, so they are still disabled here */ 2573 2574 split_page_owner(head, nr); 2575 2576 /* See comment in __split_huge_page_tail() */ 2577 if (PageAnon(head)) { 2578 /* Additional pin to swap cache */ 2579 if (PageSwapCache(head)) { 2580 page_ref_add(head, 2); 2581 xa_unlock(&swap_cache->i_pages); 2582 } else { 2583 page_ref_inc(head); 2584 } 2585 } else { 2586 /* Additional pin to page cache */ 2587 page_ref_add(head, 2); 2588 xa_unlock(&head->mapping->i_pages); 2589 } 2590 local_irq_enable(); 2591 2592 remap_page(folio, nr); 2593 2594 if (PageSwapCache(head)) { 2595 swp_entry_t entry = { .val = page_private(head) }; 2596 2597 split_swap_cluster(entry); 2598 } 2599 2600 for (i = 0; i < nr; i++) { 2601 struct page *subpage = head + i; 2602 if (subpage == page) 2603 continue; 2604 unlock_page(subpage); 2605 2606 /* 2607 * Subpages may be freed if there wasn't any mapping 2608 * like if add_to_swap() is running on a lru page that 2609 * had its mapping zapped. And freeing these pages 2610 * requires taking the lru_lock so we do the put_page 2611 * of the tail pages after the split is complete. 2612 */ 2613 free_page_and_swap_cache(subpage); 2614 } 2615 } 2616 2617 /* Racy check whether the huge page can be split */ 2618 bool can_split_folio(struct folio *folio, int *pextra_pins) 2619 { 2620 int extra_pins; 2621 2622 /* Additional pins from page cache */ 2623 if (folio_test_anon(folio)) 2624 extra_pins = folio_test_swapcache(folio) ? 2625 folio_nr_pages(folio) : 0; 2626 else 2627 extra_pins = folio_nr_pages(folio); 2628 if (pextra_pins) 2629 *pextra_pins = extra_pins; 2630 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1; 2631 } 2632 2633 /* 2634 * This function splits huge page into normal pages. @page can point to any 2635 * subpage of huge page to split. Split doesn't change the position of @page. 2636 * 2637 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2638 * The huge page must be locked. 2639 * 2640 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2641 * 2642 * Both head page and tail pages will inherit mapping, flags, and so on from 2643 * the hugepage. 2644 * 2645 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2646 * they are not mapped. 2647 * 2648 * Returns 0 if the hugepage is split successfully. 2649 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2650 * us. 2651 */ 2652 int split_huge_page_to_list(struct page *page, struct list_head *list) 2653 { 2654 struct folio *folio = page_folio(page); 2655 struct deferred_split *ds_queue = get_deferred_split_queue(&folio->page); 2656 XA_STATE(xas, &folio->mapping->i_pages, folio->index); 2657 struct anon_vma *anon_vma = NULL; 2658 struct address_space *mapping = NULL; 2659 int extra_pins, ret; 2660 pgoff_t end; 2661 bool is_hzp; 2662 2663 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); 2664 VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); 2665 2666 is_hzp = is_huge_zero_page(&folio->page); 2667 VM_WARN_ON_ONCE_FOLIO(is_hzp, folio); 2668 if (is_hzp) 2669 return -EBUSY; 2670 2671 if (folio_test_writeback(folio)) 2672 return -EBUSY; 2673 2674 if (folio_test_anon(folio)) { 2675 /* 2676 * The caller does not necessarily hold an mmap_lock that would 2677 * prevent the anon_vma disappearing so we first we take a 2678 * reference to it and then lock the anon_vma for write. This 2679 * is similar to folio_lock_anon_vma_read except the write lock 2680 * is taken to serialise against parallel split or collapse 2681 * operations. 2682 */ 2683 anon_vma = folio_get_anon_vma(folio); 2684 if (!anon_vma) { 2685 ret = -EBUSY; 2686 goto out; 2687 } 2688 end = -1; 2689 mapping = NULL; 2690 anon_vma_lock_write(anon_vma); 2691 } else { 2692 gfp_t gfp; 2693 2694 mapping = folio->mapping; 2695 2696 /* Truncated ? */ 2697 if (!mapping) { 2698 ret = -EBUSY; 2699 goto out; 2700 } 2701 2702 gfp = current_gfp_context(mapping_gfp_mask(mapping) & 2703 GFP_RECLAIM_MASK); 2704 2705 if (folio_test_private(folio) && 2706 !filemap_release_folio(folio, gfp)) { 2707 ret = -EBUSY; 2708 goto out; 2709 } 2710 2711 xas_split_alloc(&xas, folio, folio_order(folio), gfp); 2712 if (xas_error(&xas)) { 2713 ret = xas_error(&xas); 2714 goto out; 2715 } 2716 2717 anon_vma = NULL; 2718 i_mmap_lock_read(mapping); 2719 2720 /* 2721 *__split_huge_page() may need to trim off pages beyond EOF: 2722 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2723 * which cannot be nested inside the page tree lock. So note 2724 * end now: i_size itself may be changed at any moment, but 2725 * folio lock is good enough to serialize the trimming. 2726 */ 2727 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2728 if (shmem_mapping(mapping)) 2729 end = shmem_fallocend(mapping->host, end); 2730 } 2731 2732 /* 2733 * Racy check if we can split the page, before unmap_folio() will 2734 * split PMDs 2735 */ 2736 if (!can_split_folio(folio, &extra_pins)) { 2737 ret = -EAGAIN; 2738 goto out_unlock; 2739 } 2740 2741 unmap_folio(folio); 2742 2743 /* block interrupt reentry in xa_lock and spinlock */ 2744 local_irq_disable(); 2745 if (mapping) { 2746 /* 2747 * Check if the folio is present in page cache. 2748 * We assume all tail are present too, if folio is there. 2749 */ 2750 xas_lock(&xas); 2751 xas_reset(&xas); 2752 if (xas_load(&xas) != folio) 2753 goto fail; 2754 } 2755 2756 /* Prevent deferred_split_scan() touching ->_refcount */ 2757 spin_lock(&ds_queue->split_queue_lock); 2758 if (folio_ref_freeze(folio, 1 + extra_pins)) { 2759 if (!list_empty(page_deferred_list(&folio->page))) { 2760 ds_queue->split_queue_len--; 2761 list_del(page_deferred_list(&folio->page)); 2762 } 2763 spin_unlock(&ds_queue->split_queue_lock); 2764 if (mapping) { 2765 int nr = folio_nr_pages(folio); 2766 2767 xas_split(&xas, folio, folio_order(folio)); 2768 if (folio_test_swapbacked(folio)) { 2769 __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, 2770 -nr); 2771 } else { 2772 __lruvec_stat_mod_folio(folio, NR_FILE_THPS, 2773 -nr); 2774 filemap_nr_thps_dec(mapping); 2775 } 2776 } 2777 2778 __split_huge_page(page, list, end); 2779 ret = 0; 2780 } else { 2781 spin_unlock(&ds_queue->split_queue_lock); 2782 fail: 2783 if (mapping) 2784 xas_unlock(&xas); 2785 local_irq_enable(); 2786 remap_page(folio, folio_nr_pages(folio)); 2787 ret = -EAGAIN; 2788 } 2789 2790 out_unlock: 2791 if (anon_vma) { 2792 anon_vma_unlock_write(anon_vma); 2793 put_anon_vma(anon_vma); 2794 } 2795 if (mapping) 2796 i_mmap_unlock_read(mapping); 2797 out: 2798 xas_destroy(&xas); 2799 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2800 return ret; 2801 } 2802 2803 void free_transhuge_page(struct page *page) 2804 { 2805 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2806 unsigned long flags; 2807 2808 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2809 if (!list_empty(page_deferred_list(page))) { 2810 ds_queue->split_queue_len--; 2811 list_del(page_deferred_list(page)); 2812 } 2813 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2814 free_compound_page(page); 2815 } 2816 2817 void deferred_split_huge_page(struct page *page) 2818 { 2819 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2820 #ifdef CONFIG_MEMCG 2821 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 2822 #endif 2823 unsigned long flags; 2824 2825 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2826 2827 /* 2828 * The try_to_unmap() in page reclaim path might reach here too, 2829 * this may cause a race condition to corrupt deferred split queue. 2830 * And, if page reclaim is already handling the same page, it is 2831 * unnecessary to handle it again in shrinker. 2832 * 2833 * Check PageSwapCache to determine if the page is being 2834 * handled by page reclaim since THP swap would add the page into 2835 * swap cache before calling try_to_unmap(). 2836 */ 2837 if (PageSwapCache(page)) 2838 return; 2839 2840 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2841 if (list_empty(page_deferred_list(page))) { 2842 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2843 list_add_tail(page_deferred_list(page), &ds_queue->split_queue); 2844 ds_queue->split_queue_len++; 2845 #ifdef CONFIG_MEMCG 2846 if (memcg) 2847 set_shrinker_bit(memcg, page_to_nid(page), 2848 deferred_split_shrinker.id); 2849 #endif 2850 } 2851 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2852 } 2853 2854 static unsigned long deferred_split_count(struct shrinker *shrink, 2855 struct shrink_control *sc) 2856 { 2857 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2858 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2859 2860 #ifdef CONFIG_MEMCG 2861 if (sc->memcg) 2862 ds_queue = &sc->memcg->deferred_split_queue; 2863 #endif 2864 return READ_ONCE(ds_queue->split_queue_len); 2865 } 2866 2867 static unsigned long deferred_split_scan(struct shrinker *shrink, 2868 struct shrink_control *sc) 2869 { 2870 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2871 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2872 unsigned long flags; 2873 LIST_HEAD(list), *pos, *next; 2874 struct page *page; 2875 int split = 0; 2876 2877 #ifdef CONFIG_MEMCG 2878 if (sc->memcg) 2879 ds_queue = &sc->memcg->deferred_split_queue; 2880 #endif 2881 2882 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2883 /* Take pin on all head pages to avoid freeing them under us */ 2884 list_for_each_safe(pos, next, &ds_queue->split_queue) { 2885 page = list_entry((void *)pos, struct page, deferred_list); 2886 page = compound_head(page); 2887 if (get_page_unless_zero(page)) { 2888 list_move(page_deferred_list(page), &list); 2889 } else { 2890 /* We lost race with put_compound_page() */ 2891 list_del_init(page_deferred_list(page)); 2892 ds_queue->split_queue_len--; 2893 } 2894 if (!--sc->nr_to_scan) 2895 break; 2896 } 2897 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2898 2899 list_for_each_safe(pos, next, &list) { 2900 page = list_entry((void *)pos, struct page, deferred_list); 2901 if (!trylock_page(page)) 2902 goto next; 2903 /* split_huge_page() removes page from list on success */ 2904 if (!split_huge_page(page)) 2905 split++; 2906 unlock_page(page); 2907 next: 2908 put_page(page); 2909 } 2910 2911 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2912 list_splice_tail(&list, &ds_queue->split_queue); 2913 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2914 2915 /* 2916 * Stop shrinker if we didn't split any page, but the queue is empty. 2917 * This can happen if pages were freed under us. 2918 */ 2919 if (!split && list_empty(&ds_queue->split_queue)) 2920 return SHRINK_STOP; 2921 return split; 2922 } 2923 2924 static struct shrinker deferred_split_shrinker = { 2925 .count_objects = deferred_split_count, 2926 .scan_objects = deferred_split_scan, 2927 .seeks = DEFAULT_SEEKS, 2928 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | 2929 SHRINKER_NONSLAB, 2930 }; 2931 2932 #ifdef CONFIG_DEBUG_FS 2933 static void split_huge_pages_all(void) 2934 { 2935 struct zone *zone; 2936 struct page *page; 2937 unsigned long pfn, max_zone_pfn; 2938 unsigned long total = 0, split = 0; 2939 2940 pr_debug("Split all THPs\n"); 2941 for_each_zone(zone) { 2942 if (!managed_zone(zone)) 2943 continue; 2944 max_zone_pfn = zone_end_pfn(zone); 2945 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2946 int nr_pages; 2947 2948 page = pfn_to_online_page(pfn); 2949 if (!page || !get_page_unless_zero(page)) 2950 continue; 2951 2952 if (zone != page_zone(page)) 2953 goto next; 2954 2955 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 2956 goto next; 2957 2958 total++; 2959 lock_page(page); 2960 nr_pages = thp_nr_pages(page); 2961 if (!split_huge_page(page)) 2962 split++; 2963 pfn += nr_pages - 1; 2964 unlock_page(page); 2965 next: 2966 put_page(page); 2967 cond_resched(); 2968 } 2969 } 2970 2971 pr_debug("%lu of %lu THP split\n", split, total); 2972 } 2973 2974 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) 2975 { 2976 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || 2977 is_vm_hugetlb_page(vma); 2978 } 2979 2980 static int split_huge_pages_pid(int pid, unsigned long vaddr_start, 2981 unsigned long vaddr_end) 2982 { 2983 int ret = 0; 2984 struct task_struct *task; 2985 struct mm_struct *mm; 2986 unsigned long total = 0, split = 0; 2987 unsigned long addr; 2988 2989 vaddr_start &= PAGE_MASK; 2990 vaddr_end &= PAGE_MASK; 2991 2992 /* Find the task_struct from pid */ 2993 rcu_read_lock(); 2994 task = find_task_by_vpid(pid); 2995 if (!task) { 2996 rcu_read_unlock(); 2997 ret = -ESRCH; 2998 goto out; 2999 } 3000 get_task_struct(task); 3001 rcu_read_unlock(); 3002 3003 /* Find the mm_struct */ 3004 mm = get_task_mm(task); 3005 put_task_struct(task); 3006 3007 if (!mm) { 3008 ret = -EINVAL; 3009 goto out; 3010 } 3011 3012 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n", 3013 pid, vaddr_start, vaddr_end); 3014 3015 mmap_read_lock(mm); 3016 /* 3017 * always increase addr by PAGE_SIZE, since we could have a PTE page 3018 * table filled with PTE-mapped THPs, each of which is distinct. 3019 */ 3020 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { 3021 struct vm_area_struct *vma = vma_lookup(mm, addr); 3022 struct page *page; 3023 3024 if (!vma) 3025 break; 3026 3027 /* skip special VMA and hugetlb VMA */ 3028 if (vma_not_suitable_for_thp_split(vma)) { 3029 addr = vma->vm_end; 3030 continue; 3031 } 3032 3033 /* FOLL_DUMP to ignore special (like zero) pages */ 3034 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); 3035 3036 if (IS_ERR_OR_NULL(page)) 3037 continue; 3038 3039 if (!is_transparent_hugepage(page)) 3040 goto next; 3041 3042 total++; 3043 if (!can_split_folio(page_folio(page), NULL)) 3044 goto next; 3045 3046 if (!trylock_page(page)) 3047 goto next; 3048 3049 if (!split_huge_page(page)) 3050 split++; 3051 3052 unlock_page(page); 3053 next: 3054 put_page(page); 3055 cond_resched(); 3056 } 3057 mmap_read_unlock(mm); 3058 mmput(mm); 3059 3060 pr_debug("%lu of %lu THP split\n", split, total); 3061 3062 out: 3063 return ret; 3064 } 3065 3066 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, 3067 pgoff_t off_end) 3068 { 3069 struct filename *file; 3070 struct file *candidate; 3071 struct address_space *mapping; 3072 int ret = -EINVAL; 3073 pgoff_t index; 3074 int nr_pages = 1; 3075 unsigned long total = 0, split = 0; 3076 3077 file = getname_kernel(file_path); 3078 if (IS_ERR(file)) 3079 return ret; 3080 3081 candidate = file_open_name(file, O_RDONLY, 0); 3082 if (IS_ERR(candidate)) 3083 goto out; 3084 3085 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", 3086 file_path, off_start, off_end); 3087 3088 mapping = candidate->f_mapping; 3089 3090 for (index = off_start; index < off_end; index += nr_pages) { 3091 struct folio *folio = __filemap_get_folio(mapping, index, 3092 FGP_ENTRY, 0); 3093 3094 nr_pages = 1; 3095 if (xa_is_value(folio) || !folio) 3096 continue; 3097 3098 if (!folio_test_large(folio)) 3099 goto next; 3100 3101 total++; 3102 nr_pages = folio_nr_pages(folio); 3103 3104 if (!folio_trylock(folio)) 3105 goto next; 3106 3107 if (!split_folio(folio)) 3108 split++; 3109 3110 folio_unlock(folio); 3111 next: 3112 folio_put(folio); 3113 cond_resched(); 3114 } 3115 3116 filp_close(candidate, NULL); 3117 ret = 0; 3118 3119 pr_debug("%lu of %lu file-backed THP split\n", split, total); 3120 out: 3121 putname(file); 3122 return ret; 3123 } 3124 3125 #define MAX_INPUT_BUF_SZ 255 3126 3127 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, 3128 size_t count, loff_t *ppops) 3129 { 3130 static DEFINE_MUTEX(split_debug_mutex); 3131 ssize_t ret; 3132 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */ 3133 char input_buf[MAX_INPUT_BUF_SZ]; 3134 int pid; 3135 unsigned long vaddr_start, vaddr_end; 3136 3137 ret = mutex_lock_interruptible(&split_debug_mutex); 3138 if (ret) 3139 return ret; 3140 3141 ret = -EFAULT; 3142 3143 memset(input_buf, 0, MAX_INPUT_BUF_SZ); 3144 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) 3145 goto out; 3146 3147 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; 3148 3149 if (input_buf[0] == '/') { 3150 char *tok; 3151 char *buf = input_buf; 3152 char file_path[MAX_INPUT_BUF_SZ]; 3153 pgoff_t off_start = 0, off_end = 0; 3154 size_t input_len = strlen(input_buf); 3155 3156 tok = strsep(&buf, ","); 3157 if (tok) { 3158 strcpy(file_path, tok); 3159 } else { 3160 ret = -EINVAL; 3161 goto out; 3162 } 3163 3164 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end); 3165 if (ret != 2) { 3166 ret = -EINVAL; 3167 goto out; 3168 } 3169 ret = split_huge_pages_in_file(file_path, off_start, off_end); 3170 if (!ret) 3171 ret = input_len; 3172 3173 goto out; 3174 } 3175 3176 ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end); 3177 if (ret == 1 && pid == 1) { 3178 split_huge_pages_all(); 3179 ret = strlen(input_buf); 3180 goto out; 3181 } else if (ret != 3) { 3182 ret = -EINVAL; 3183 goto out; 3184 } 3185 3186 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end); 3187 if (!ret) 3188 ret = strlen(input_buf); 3189 out: 3190 mutex_unlock(&split_debug_mutex); 3191 return ret; 3192 3193 } 3194 3195 static const struct file_operations split_huge_pages_fops = { 3196 .owner = THIS_MODULE, 3197 .write = split_huge_pages_write, 3198 .llseek = no_llseek, 3199 }; 3200 3201 static int __init split_huge_pages_debugfs(void) 3202 { 3203 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 3204 &split_huge_pages_fops); 3205 return 0; 3206 } 3207 late_initcall(split_huge_pages_debugfs); 3208 #endif 3209 3210 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 3211 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 3212 struct page *page) 3213 { 3214 struct vm_area_struct *vma = pvmw->vma; 3215 struct mm_struct *mm = vma->vm_mm; 3216 unsigned long address = pvmw->address; 3217 bool anon_exclusive; 3218 pmd_t pmdval; 3219 swp_entry_t entry; 3220 pmd_t pmdswp; 3221 3222 if (!(pvmw->pmd && !pvmw->pte)) 3223 return 0; 3224 3225 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 3226 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 3227 3228 /* See page_try_share_anon_rmap(): invalidate PMD first. */ 3229 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 3230 if (anon_exclusive && page_try_share_anon_rmap(page)) { 3231 set_pmd_at(mm, address, pvmw->pmd, pmdval); 3232 return -EBUSY; 3233 } 3234 3235 if (pmd_dirty(pmdval)) 3236 set_page_dirty(page); 3237 if (pmd_write(pmdval)) 3238 entry = make_writable_migration_entry(page_to_pfn(page)); 3239 else if (anon_exclusive) 3240 entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); 3241 else 3242 entry = make_readable_migration_entry(page_to_pfn(page)); 3243 if (pmd_young(pmdval)) 3244 entry = make_migration_entry_young(entry); 3245 if (pmd_dirty(pmdval)) 3246 entry = make_migration_entry_dirty(entry); 3247 pmdswp = swp_entry_to_pmd(entry); 3248 if (pmd_soft_dirty(pmdval)) 3249 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3250 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3251 page_remove_rmap(page, vma, true); 3252 put_page(page); 3253 trace_set_migration_pmd(address, pmd_val(pmdswp)); 3254 3255 return 0; 3256 } 3257 3258 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3259 { 3260 struct vm_area_struct *vma = pvmw->vma; 3261 struct mm_struct *mm = vma->vm_mm; 3262 unsigned long address = pvmw->address; 3263 unsigned long haddr = address & HPAGE_PMD_MASK; 3264 pmd_t pmde; 3265 swp_entry_t entry; 3266 3267 if (!(pvmw->pmd && !pvmw->pte)) 3268 return; 3269 3270 entry = pmd_to_swp_entry(*pvmw->pmd); 3271 get_page(new); 3272 pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot)); 3273 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3274 pmde = pmd_mksoft_dirty(pmde); 3275 if (is_writable_migration_entry(entry)) 3276 pmde = maybe_pmd_mkwrite(pmde, vma); 3277 if (pmd_swp_uffd_wp(*pvmw->pmd)) 3278 pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde)); 3279 if (!is_migration_entry_young(entry)) 3280 pmde = pmd_mkold(pmde); 3281 /* NOTE: this may contain setting soft-dirty on some archs */ 3282 if (PageDirty(new) && is_migration_entry_dirty(entry)) 3283 pmde = pmd_mkdirty(pmde); 3284 3285 if (PageAnon(new)) { 3286 rmap_t rmap_flags = RMAP_COMPOUND; 3287 3288 if (!is_readable_migration_entry(entry)) 3289 rmap_flags |= RMAP_EXCLUSIVE; 3290 3291 page_add_anon_rmap(new, vma, haddr, rmap_flags); 3292 } else { 3293 page_add_file_rmap(new, vma, true); 3294 } 3295 VM_BUG_ON(pmd_write(pmde) && PageAnon(new) && !PageAnonExclusive(new)); 3296 set_pmd_at(mm, haddr, pvmw->pmd, pmde); 3297 3298 /* No need to invalidate - it was non-present before */ 3299 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3300 trace_remove_migration_pmd(address, pmd_val(pmde)); 3301 } 3302 #endif 3303