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/dax.h> 22 #include <linux/khugepaged.h> 23 #include <linux/freezer.h> 24 #include <linux/pfn_t.h> 25 #include <linux/mman.h> 26 #include <linux/memremap.h> 27 #include <linux/pagemap.h> 28 #include <linux/debugfs.h> 29 #include <linux/migrate.h> 30 #include <linux/hashtable.h> 31 #include <linux/userfaultfd_k.h> 32 #include <linux/page_idle.h> 33 #include <linux/shmem_fs.h> 34 #include <linux/oom.h> 35 #include <linux/numa.h> 36 #include <linux/page_owner.h> 37 #include <linux/sched/sysctl.h> 38 39 #include <asm/tlb.h> 40 #include <asm/pgalloc.h> 41 #include "internal.h" 42 #include "swap.h" 43 44 #define CREATE_TRACE_POINTS 45 #include <trace/events/thp.h> 46 47 /* 48 * By default, transparent hugepage support is disabled in order to avoid 49 * risking an increased memory footprint for applications that are not 50 * guaranteed to benefit from it. When transparent hugepage support is 51 * enabled, it is for all mappings, and khugepaged scans all mappings. 52 * Defrag is invoked by khugepaged hugepage allocations and by page faults 53 * for all hugepage allocations. 54 */ 55 unsigned long transparent_hugepage_flags __read_mostly = 56 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 57 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 58 #endif 59 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 60 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 61 #endif 62 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 63 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 64 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 65 66 static struct shrinker deferred_split_shrinker; 67 68 static atomic_t huge_zero_refcount; 69 struct page *huge_zero_page __read_mostly; 70 unsigned long huge_zero_pfn __read_mostly = ~0UL; 71 72 static inline bool file_thp_enabled(struct vm_area_struct *vma) 73 { 74 return transhuge_vma_enabled(vma, vma->vm_flags) && vma->vm_file && 75 !inode_is_open_for_write(vma->vm_file->f_inode) && 76 (vma->vm_flags & VM_EXEC); 77 } 78 79 bool transparent_hugepage_active(struct vm_area_struct *vma) 80 { 81 /* The addr is used to check if the vma size fits */ 82 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE; 83 84 if (!transhuge_vma_suitable(vma, addr)) 85 return false; 86 if (vma_is_anonymous(vma)) 87 return __transparent_hugepage_enabled(vma); 88 if (vma_is_shmem(vma)) 89 return shmem_huge_enabled(vma); 90 if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) 91 return file_thp_enabled(vma); 92 93 return false; 94 } 95 96 static bool get_huge_zero_page(void) 97 { 98 struct page *zero_page; 99 retry: 100 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 101 return true; 102 103 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 104 HPAGE_PMD_ORDER); 105 if (!zero_page) { 106 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 107 return false; 108 } 109 count_vm_event(THP_ZERO_PAGE_ALLOC); 110 preempt_disable(); 111 if (cmpxchg(&huge_zero_page, NULL, zero_page)) { 112 preempt_enable(); 113 __free_pages(zero_page, compound_order(zero_page)); 114 goto retry; 115 } 116 WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page)); 117 118 /* We take additional reference here. It will be put back by shrinker */ 119 atomic_set(&huge_zero_refcount, 2); 120 preempt_enable(); 121 return true; 122 } 123 124 static void put_huge_zero_page(void) 125 { 126 /* 127 * Counter should never go to zero here. Only shrinker can put 128 * last reference. 129 */ 130 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 131 } 132 133 struct page *mm_get_huge_zero_page(struct mm_struct *mm) 134 { 135 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 136 return READ_ONCE(huge_zero_page); 137 138 if (!get_huge_zero_page()) 139 return NULL; 140 141 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 142 put_huge_zero_page(); 143 144 return READ_ONCE(huge_zero_page); 145 } 146 147 void mm_put_huge_zero_page(struct mm_struct *mm) 148 { 149 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 150 put_huge_zero_page(); 151 } 152 153 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 154 struct shrink_control *sc) 155 { 156 /* we can free zero page only if last reference remains */ 157 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 158 } 159 160 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 161 struct shrink_control *sc) 162 { 163 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 164 struct page *zero_page = xchg(&huge_zero_page, NULL); 165 BUG_ON(zero_page == NULL); 166 WRITE_ONCE(huge_zero_pfn, ~0UL); 167 __free_pages(zero_page, compound_order(zero_page)); 168 return HPAGE_PMD_NR; 169 } 170 171 return 0; 172 } 173 174 static struct shrinker huge_zero_page_shrinker = { 175 .count_objects = shrink_huge_zero_page_count, 176 .scan_objects = shrink_huge_zero_page_scan, 177 .seeks = DEFAULT_SEEKS, 178 }; 179 180 #ifdef CONFIG_SYSFS 181 static ssize_t enabled_show(struct kobject *kobj, 182 struct kobj_attribute *attr, char *buf) 183 { 184 const char *output; 185 186 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 187 output = "[always] madvise never"; 188 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 189 &transparent_hugepage_flags)) 190 output = "always [madvise] never"; 191 else 192 output = "always madvise [never]"; 193 194 return sysfs_emit(buf, "%s\n", output); 195 } 196 197 static ssize_t enabled_store(struct kobject *kobj, 198 struct kobj_attribute *attr, 199 const char *buf, size_t count) 200 { 201 ssize_t ret = count; 202 203 if (sysfs_streq(buf, "always")) { 204 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 205 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 206 } else if (sysfs_streq(buf, "madvise")) { 207 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 208 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 209 } else if (sysfs_streq(buf, "never")) { 210 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 211 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 212 } else 213 ret = -EINVAL; 214 215 if (ret > 0) { 216 int err = start_stop_khugepaged(); 217 if (err) 218 ret = err; 219 } 220 return ret; 221 } 222 static struct kobj_attribute enabled_attr = 223 __ATTR(enabled, 0644, enabled_show, enabled_store); 224 225 ssize_t single_hugepage_flag_show(struct kobject *kobj, 226 struct kobj_attribute *attr, char *buf, 227 enum transparent_hugepage_flag flag) 228 { 229 return sysfs_emit(buf, "%d\n", 230 !!test_bit(flag, &transparent_hugepage_flags)); 231 } 232 233 ssize_t single_hugepage_flag_store(struct kobject *kobj, 234 struct kobj_attribute *attr, 235 const char *buf, size_t count, 236 enum transparent_hugepage_flag flag) 237 { 238 unsigned long value; 239 int ret; 240 241 ret = kstrtoul(buf, 10, &value); 242 if (ret < 0) 243 return ret; 244 if (value > 1) 245 return -EINVAL; 246 247 if (value) 248 set_bit(flag, &transparent_hugepage_flags); 249 else 250 clear_bit(flag, &transparent_hugepage_flags); 251 252 return count; 253 } 254 255 static ssize_t defrag_show(struct kobject *kobj, 256 struct kobj_attribute *attr, char *buf) 257 { 258 const char *output; 259 260 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, 261 &transparent_hugepage_flags)) 262 output = "[always] defer defer+madvise madvise never"; 263 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, 264 &transparent_hugepage_flags)) 265 output = "always [defer] defer+madvise madvise never"; 266 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, 267 &transparent_hugepage_flags)) 268 output = "always defer [defer+madvise] madvise never"; 269 else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, 270 &transparent_hugepage_flags)) 271 output = "always defer defer+madvise [madvise] never"; 272 else 273 output = "always defer defer+madvise madvise [never]"; 274 275 return sysfs_emit(buf, "%s\n", output); 276 } 277 278 static ssize_t defrag_store(struct kobject *kobj, 279 struct kobj_attribute *attr, 280 const char *buf, size_t count) 281 { 282 if (sysfs_streq(buf, "always")) { 283 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 284 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 285 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 286 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 287 } else if (sysfs_streq(buf, "defer+madvise")) { 288 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 289 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 290 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 291 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 292 } else if (sysfs_streq(buf, "defer")) { 293 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 294 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 295 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 296 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 297 } else if (sysfs_streq(buf, "madvise")) { 298 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 299 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 300 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 301 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 302 } else if (sysfs_streq(buf, "never")) { 303 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 304 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 305 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 306 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 307 } else 308 return -EINVAL; 309 310 return count; 311 } 312 static struct kobj_attribute defrag_attr = 313 __ATTR(defrag, 0644, defrag_show, defrag_store); 314 315 static ssize_t use_zero_page_show(struct kobject *kobj, 316 struct kobj_attribute *attr, char *buf) 317 { 318 return single_hugepage_flag_show(kobj, attr, buf, 319 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 320 } 321 static ssize_t use_zero_page_store(struct kobject *kobj, 322 struct kobj_attribute *attr, const char *buf, size_t count) 323 { 324 return single_hugepage_flag_store(kobj, attr, buf, count, 325 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 326 } 327 static struct kobj_attribute use_zero_page_attr = 328 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); 329 330 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 331 struct kobj_attribute *attr, char *buf) 332 { 333 return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE); 334 } 335 static struct kobj_attribute hpage_pmd_size_attr = 336 __ATTR_RO(hpage_pmd_size); 337 338 static struct attribute *hugepage_attr[] = { 339 &enabled_attr.attr, 340 &defrag_attr.attr, 341 &use_zero_page_attr.attr, 342 &hpage_pmd_size_attr.attr, 343 #ifdef CONFIG_SHMEM 344 &shmem_enabled_attr.attr, 345 #endif 346 NULL, 347 }; 348 349 static const struct attribute_group hugepage_attr_group = { 350 .attrs = hugepage_attr, 351 }; 352 353 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 354 { 355 int err; 356 357 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 358 if (unlikely(!*hugepage_kobj)) { 359 pr_err("failed to create transparent hugepage kobject\n"); 360 return -ENOMEM; 361 } 362 363 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 364 if (err) { 365 pr_err("failed to register transparent hugepage group\n"); 366 goto delete_obj; 367 } 368 369 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 370 if (err) { 371 pr_err("failed to register transparent hugepage group\n"); 372 goto remove_hp_group; 373 } 374 375 return 0; 376 377 remove_hp_group: 378 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 379 delete_obj: 380 kobject_put(*hugepage_kobj); 381 return err; 382 } 383 384 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 385 { 386 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 387 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 388 kobject_put(hugepage_kobj); 389 } 390 #else 391 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 392 { 393 return 0; 394 } 395 396 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 397 { 398 } 399 #endif /* CONFIG_SYSFS */ 400 401 static int __init hugepage_init(void) 402 { 403 int err; 404 struct kobject *hugepage_kobj; 405 406 if (!has_transparent_hugepage()) { 407 /* 408 * Hardware doesn't support hugepages, hence disable 409 * DAX PMD support. 410 */ 411 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_NEVER_DAX; 412 return -EINVAL; 413 } 414 415 /* 416 * hugepages can't be allocated by the buddy allocator 417 */ 418 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); 419 /* 420 * we use page->mapping and page->index in second tail page 421 * as list_head: assuming THP order >= 2 422 */ 423 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); 424 425 err = hugepage_init_sysfs(&hugepage_kobj); 426 if (err) 427 goto err_sysfs; 428 429 err = khugepaged_init(); 430 if (err) 431 goto err_slab; 432 433 err = register_shrinker(&huge_zero_page_shrinker); 434 if (err) 435 goto err_hzp_shrinker; 436 err = register_shrinker(&deferred_split_shrinker); 437 if (err) 438 goto err_split_shrinker; 439 440 /* 441 * By default disable transparent hugepages on smaller systems, 442 * where the extra memory used could hurt more than TLB overhead 443 * is likely to save. The admin can still enable it through /sys. 444 */ 445 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 446 transparent_hugepage_flags = 0; 447 return 0; 448 } 449 450 err = start_stop_khugepaged(); 451 if (err) 452 goto err_khugepaged; 453 454 return 0; 455 err_khugepaged: 456 unregister_shrinker(&deferred_split_shrinker); 457 err_split_shrinker: 458 unregister_shrinker(&huge_zero_page_shrinker); 459 err_hzp_shrinker: 460 khugepaged_destroy(); 461 err_slab: 462 hugepage_exit_sysfs(hugepage_kobj); 463 err_sysfs: 464 return err; 465 } 466 subsys_initcall(hugepage_init); 467 468 static int __init setup_transparent_hugepage(char *str) 469 { 470 int ret = 0; 471 if (!str) 472 goto out; 473 if (!strcmp(str, "always")) { 474 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 475 &transparent_hugepage_flags); 476 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 477 &transparent_hugepage_flags); 478 ret = 1; 479 } else if (!strcmp(str, "madvise")) { 480 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 481 &transparent_hugepage_flags); 482 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 483 &transparent_hugepage_flags); 484 ret = 1; 485 } else if (!strcmp(str, "never")) { 486 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 487 &transparent_hugepage_flags); 488 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 489 &transparent_hugepage_flags); 490 ret = 1; 491 } 492 out: 493 if (!ret) 494 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 495 return ret; 496 } 497 __setup("transparent_hugepage=", setup_transparent_hugepage); 498 499 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 500 { 501 if (likely(vma->vm_flags & VM_WRITE)) 502 pmd = pmd_mkwrite(pmd); 503 return pmd; 504 } 505 506 #ifdef CONFIG_MEMCG 507 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 508 { 509 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 510 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 511 512 if (memcg) 513 return &memcg->deferred_split_queue; 514 else 515 return &pgdat->deferred_split_queue; 516 } 517 #else 518 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 519 { 520 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 521 522 return &pgdat->deferred_split_queue; 523 } 524 #endif 525 526 void prep_transhuge_page(struct page *page) 527 { 528 /* 529 * we use page->mapping and page->indexlru in second tail page 530 * as list_head: assuming THP order >= 2 531 */ 532 533 INIT_LIST_HEAD(page_deferred_list(page)); 534 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); 535 } 536 537 static inline bool is_transparent_hugepage(struct page *page) 538 { 539 if (!PageCompound(page)) 540 return false; 541 542 page = compound_head(page); 543 return is_huge_zero_page(page) || 544 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR; 545 } 546 547 static unsigned long __thp_get_unmapped_area(struct file *filp, 548 unsigned long addr, unsigned long len, 549 loff_t off, unsigned long flags, unsigned long size) 550 { 551 loff_t off_end = off + len; 552 loff_t off_align = round_up(off, size); 553 unsigned long len_pad, ret; 554 555 if (off_end <= off_align || (off_end - off_align) < size) 556 return 0; 557 558 len_pad = len + size; 559 if (len_pad < len || (off + len_pad) < off) 560 return 0; 561 562 ret = current->mm->get_unmapped_area(filp, addr, len_pad, 563 off >> PAGE_SHIFT, flags); 564 565 /* 566 * The failure might be due to length padding. The caller will retry 567 * without the padding. 568 */ 569 if (IS_ERR_VALUE(ret)) 570 return 0; 571 572 /* 573 * Do not try to align to THP boundary if allocation at the address 574 * hint succeeds. 575 */ 576 if (ret == addr) 577 return addr; 578 579 ret += (off - ret) & (size - 1); 580 return ret; 581 } 582 583 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 584 unsigned long len, unsigned long pgoff, unsigned long flags) 585 { 586 unsigned long ret; 587 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 588 589 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE); 590 if (ret) 591 return ret; 592 593 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 594 } 595 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 596 597 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 598 struct page *page, gfp_t gfp) 599 { 600 struct vm_area_struct *vma = vmf->vma; 601 pgtable_t pgtable; 602 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 603 vm_fault_t ret = 0; 604 605 VM_BUG_ON_PAGE(!PageCompound(page), page); 606 607 if (mem_cgroup_charge(page_folio(page), vma->vm_mm, gfp)) { 608 put_page(page); 609 count_vm_event(THP_FAULT_FALLBACK); 610 count_vm_event(THP_FAULT_FALLBACK_CHARGE); 611 return VM_FAULT_FALLBACK; 612 } 613 cgroup_throttle_swaprate(page, gfp); 614 615 pgtable = pte_alloc_one(vma->vm_mm); 616 if (unlikely(!pgtable)) { 617 ret = VM_FAULT_OOM; 618 goto release; 619 } 620 621 clear_huge_page(page, vmf->address, HPAGE_PMD_NR); 622 /* 623 * The memory barrier inside __SetPageUptodate makes sure that 624 * clear_huge_page writes become visible before the set_pmd_at() 625 * write. 626 */ 627 __SetPageUptodate(page); 628 629 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 630 if (unlikely(!pmd_none(*vmf->pmd))) { 631 goto unlock_release; 632 } else { 633 pmd_t entry; 634 635 ret = check_stable_address_space(vma->vm_mm); 636 if (ret) 637 goto unlock_release; 638 639 /* Deliver the page fault to userland */ 640 if (userfaultfd_missing(vma)) { 641 spin_unlock(vmf->ptl); 642 put_page(page); 643 pte_free(vma->vm_mm, pgtable); 644 ret = handle_userfault(vmf, VM_UFFD_MISSING); 645 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 646 return ret; 647 } 648 649 entry = mk_huge_pmd(page, vma->vm_page_prot); 650 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 651 page_add_new_anon_rmap(page, vma, haddr); 652 lru_cache_add_inactive_or_unevictable(page, vma); 653 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 654 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 655 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 656 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 657 mm_inc_nr_ptes(vma->vm_mm); 658 spin_unlock(vmf->ptl); 659 count_vm_event(THP_FAULT_ALLOC); 660 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC); 661 } 662 663 return 0; 664 unlock_release: 665 spin_unlock(vmf->ptl); 666 release: 667 if (pgtable) 668 pte_free(vma->vm_mm, pgtable); 669 put_page(page); 670 return ret; 671 672 } 673 674 /* 675 * always: directly stall for all thp allocations 676 * defer: wake kswapd and fail if not immediately available 677 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 678 * fail if not immediately available 679 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 680 * available 681 * never: never stall for any thp allocation 682 */ 683 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma) 684 { 685 const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE); 686 687 /* Always do synchronous compaction */ 688 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 689 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 690 691 /* Kick kcompactd and fail quickly */ 692 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 693 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; 694 695 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 696 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 697 return GFP_TRANSHUGE_LIGHT | 698 (vma_madvised ? __GFP_DIRECT_RECLAIM : 699 __GFP_KSWAPD_RECLAIM); 700 701 /* Only do synchronous compaction if madvised */ 702 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 703 return GFP_TRANSHUGE_LIGHT | 704 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 705 706 return GFP_TRANSHUGE_LIGHT; 707 } 708 709 /* Caller must hold page table lock. */ 710 static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, 711 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 712 struct page *zero_page) 713 { 714 pmd_t entry; 715 if (!pmd_none(*pmd)) 716 return; 717 entry = mk_pmd(zero_page, vma->vm_page_prot); 718 entry = pmd_mkhuge(entry); 719 if (pgtable) 720 pgtable_trans_huge_deposit(mm, pmd, pgtable); 721 set_pmd_at(mm, haddr, pmd, entry); 722 mm_inc_nr_ptes(mm); 723 } 724 725 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 726 { 727 struct vm_area_struct *vma = vmf->vma; 728 gfp_t gfp; 729 struct page *page; 730 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 731 732 if (!transhuge_vma_suitable(vma, haddr)) 733 return VM_FAULT_FALLBACK; 734 if (unlikely(anon_vma_prepare(vma))) 735 return VM_FAULT_OOM; 736 if (unlikely(khugepaged_enter(vma, vma->vm_flags))) 737 return VM_FAULT_OOM; 738 if (!(vmf->flags & FAULT_FLAG_WRITE) && 739 !mm_forbids_zeropage(vma->vm_mm) && 740 transparent_hugepage_use_zero_page()) { 741 pgtable_t pgtable; 742 struct page *zero_page; 743 vm_fault_t ret; 744 pgtable = pte_alloc_one(vma->vm_mm); 745 if (unlikely(!pgtable)) 746 return VM_FAULT_OOM; 747 zero_page = mm_get_huge_zero_page(vma->vm_mm); 748 if (unlikely(!zero_page)) { 749 pte_free(vma->vm_mm, pgtable); 750 count_vm_event(THP_FAULT_FALLBACK); 751 return VM_FAULT_FALLBACK; 752 } 753 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 754 ret = 0; 755 if (pmd_none(*vmf->pmd)) { 756 ret = check_stable_address_space(vma->vm_mm); 757 if (ret) { 758 spin_unlock(vmf->ptl); 759 pte_free(vma->vm_mm, pgtable); 760 } else if (userfaultfd_missing(vma)) { 761 spin_unlock(vmf->ptl); 762 pte_free(vma->vm_mm, pgtable); 763 ret = handle_userfault(vmf, VM_UFFD_MISSING); 764 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 765 } else { 766 set_huge_zero_page(pgtable, vma->vm_mm, vma, 767 haddr, vmf->pmd, zero_page); 768 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 769 spin_unlock(vmf->ptl); 770 } 771 } else { 772 spin_unlock(vmf->ptl); 773 pte_free(vma->vm_mm, pgtable); 774 } 775 return ret; 776 } 777 gfp = vma_thp_gfp_mask(vma); 778 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); 779 if (unlikely(!page)) { 780 count_vm_event(THP_FAULT_FALLBACK); 781 return VM_FAULT_FALLBACK; 782 } 783 prep_transhuge_page(page); 784 return __do_huge_pmd_anonymous_page(vmf, page, gfp); 785 } 786 787 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 788 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 789 pgtable_t pgtable) 790 { 791 struct mm_struct *mm = vma->vm_mm; 792 pmd_t entry; 793 spinlock_t *ptl; 794 795 ptl = pmd_lock(mm, pmd); 796 if (!pmd_none(*pmd)) { 797 if (write) { 798 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 799 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 800 goto out_unlock; 801 } 802 entry = pmd_mkyoung(*pmd); 803 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 804 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 805 update_mmu_cache_pmd(vma, addr, pmd); 806 } 807 808 goto out_unlock; 809 } 810 811 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 812 if (pfn_t_devmap(pfn)) 813 entry = pmd_mkdevmap(entry); 814 if (write) { 815 entry = pmd_mkyoung(pmd_mkdirty(entry)); 816 entry = maybe_pmd_mkwrite(entry, vma); 817 } 818 819 if (pgtable) { 820 pgtable_trans_huge_deposit(mm, pmd, pgtable); 821 mm_inc_nr_ptes(mm); 822 pgtable = NULL; 823 } 824 825 set_pmd_at(mm, addr, pmd, entry); 826 update_mmu_cache_pmd(vma, addr, pmd); 827 828 out_unlock: 829 spin_unlock(ptl); 830 if (pgtable) 831 pte_free(mm, pgtable); 832 } 833 834 /** 835 * vmf_insert_pfn_pmd_prot - insert a pmd size pfn 836 * @vmf: Structure describing the fault 837 * @pfn: pfn to insert 838 * @pgprot: page protection to use 839 * @write: whether it's a write fault 840 * 841 * Insert a pmd size pfn. See vmf_insert_pfn() for additional info and 842 * also consult the vmf_insert_mixed_prot() documentation when 843 * @pgprot != @vmf->vma->vm_page_prot. 844 * 845 * Return: vm_fault_t value. 846 */ 847 vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn, 848 pgprot_t pgprot, bool write) 849 { 850 unsigned long addr = vmf->address & PMD_MASK; 851 struct vm_area_struct *vma = vmf->vma; 852 pgtable_t pgtable = NULL; 853 854 /* 855 * If we had pmd_special, we could avoid all these restrictions, 856 * but we need to be consistent with PTEs and architectures that 857 * can't support a 'special' bit. 858 */ 859 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 860 !pfn_t_devmap(pfn)); 861 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 862 (VM_PFNMAP|VM_MIXEDMAP)); 863 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 864 865 if (addr < vma->vm_start || addr >= vma->vm_end) 866 return VM_FAULT_SIGBUS; 867 868 if (arch_needs_pgtable_deposit()) { 869 pgtable = pte_alloc_one(vma->vm_mm); 870 if (!pgtable) 871 return VM_FAULT_OOM; 872 } 873 874 track_pfn_insert(vma, &pgprot, pfn); 875 876 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 877 return VM_FAULT_NOPAGE; 878 } 879 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd_prot); 880 881 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 882 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 883 { 884 if (likely(vma->vm_flags & VM_WRITE)) 885 pud = pud_mkwrite(pud); 886 return pud; 887 } 888 889 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 890 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) 891 { 892 struct mm_struct *mm = vma->vm_mm; 893 pud_t entry; 894 spinlock_t *ptl; 895 896 ptl = pud_lock(mm, pud); 897 if (!pud_none(*pud)) { 898 if (write) { 899 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 900 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 901 goto out_unlock; 902 } 903 entry = pud_mkyoung(*pud); 904 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 905 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 906 update_mmu_cache_pud(vma, addr, pud); 907 } 908 goto out_unlock; 909 } 910 911 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 912 if (pfn_t_devmap(pfn)) 913 entry = pud_mkdevmap(entry); 914 if (write) { 915 entry = pud_mkyoung(pud_mkdirty(entry)); 916 entry = maybe_pud_mkwrite(entry, vma); 917 } 918 set_pud_at(mm, addr, pud, entry); 919 update_mmu_cache_pud(vma, addr, pud); 920 921 out_unlock: 922 spin_unlock(ptl); 923 } 924 925 /** 926 * vmf_insert_pfn_pud_prot - insert a pud size pfn 927 * @vmf: Structure describing the fault 928 * @pfn: pfn to insert 929 * @pgprot: page protection to use 930 * @write: whether it's a write fault 931 * 932 * Insert a pud size pfn. See vmf_insert_pfn() for additional info and 933 * also consult the vmf_insert_mixed_prot() documentation when 934 * @pgprot != @vmf->vma->vm_page_prot. 935 * 936 * Return: vm_fault_t value. 937 */ 938 vm_fault_t vmf_insert_pfn_pud_prot(struct vm_fault *vmf, pfn_t pfn, 939 pgprot_t pgprot, bool write) 940 { 941 unsigned long addr = vmf->address & PUD_MASK; 942 struct vm_area_struct *vma = vmf->vma; 943 944 /* 945 * If we had pud_special, we could avoid all these restrictions, 946 * but we need to be consistent with PTEs and architectures that 947 * can't support a 'special' bit. 948 */ 949 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 950 !pfn_t_devmap(pfn)); 951 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 952 (VM_PFNMAP|VM_MIXEDMAP)); 953 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 954 955 if (addr < vma->vm_start || addr >= vma->vm_end) 956 return VM_FAULT_SIGBUS; 957 958 track_pfn_insert(vma, &pgprot, pfn); 959 960 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); 961 return VM_FAULT_NOPAGE; 962 } 963 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud_prot); 964 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 965 966 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 967 pmd_t *pmd, int flags) 968 { 969 pmd_t _pmd; 970 971 _pmd = pmd_mkyoung(*pmd); 972 if (flags & FOLL_WRITE) 973 _pmd = pmd_mkdirty(_pmd); 974 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 975 pmd, _pmd, flags & FOLL_WRITE)) 976 update_mmu_cache_pmd(vma, addr, pmd); 977 } 978 979 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 980 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 981 { 982 unsigned long pfn = pmd_pfn(*pmd); 983 struct mm_struct *mm = vma->vm_mm; 984 struct page *page; 985 986 assert_spin_locked(pmd_lockptr(mm, pmd)); 987 988 /* 989 * When we COW a devmap PMD entry, we split it into PTEs, so we should 990 * not be in this function with `flags & FOLL_COW` set. 991 */ 992 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); 993 994 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 995 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 996 (FOLL_PIN | FOLL_GET))) 997 return NULL; 998 999 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 1000 return NULL; 1001 1002 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 1003 /* pass */; 1004 else 1005 return NULL; 1006 1007 if (flags & FOLL_TOUCH) 1008 touch_pmd(vma, addr, pmd, flags); 1009 1010 /* 1011 * device mapped pages can only be returned if the 1012 * caller will manage the page reference count. 1013 */ 1014 if (!(flags & (FOLL_GET | FOLL_PIN))) 1015 return ERR_PTR(-EEXIST); 1016 1017 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 1018 *pgmap = get_dev_pagemap(pfn, *pgmap); 1019 if (!*pgmap) 1020 return ERR_PTR(-EFAULT); 1021 page = pfn_to_page(pfn); 1022 if (!try_grab_page(page, flags)) 1023 page = ERR_PTR(-ENOMEM); 1024 1025 return page; 1026 } 1027 1028 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1029 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 1030 struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) 1031 { 1032 spinlock_t *dst_ptl, *src_ptl; 1033 struct page *src_page; 1034 pmd_t pmd; 1035 pgtable_t pgtable = NULL; 1036 int ret = -ENOMEM; 1037 1038 /* Skip if can be re-fill on fault */ 1039 if (!vma_is_anonymous(dst_vma)) 1040 return 0; 1041 1042 pgtable = pte_alloc_one(dst_mm); 1043 if (unlikely(!pgtable)) 1044 goto out; 1045 1046 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1047 src_ptl = pmd_lockptr(src_mm, src_pmd); 1048 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1049 1050 ret = -EAGAIN; 1051 pmd = *src_pmd; 1052 1053 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1054 if (unlikely(is_swap_pmd(pmd))) { 1055 swp_entry_t entry = pmd_to_swp_entry(pmd); 1056 1057 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1058 if (!is_readable_migration_entry(entry)) { 1059 entry = make_readable_migration_entry( 1060 swp_offset(entry)); 1061 pmd = swp_entry_to_pmd(entry); 1062 if (pmd_swp_soft_dirty(*src_pmd)) 1063 pmd = pmd_swp_mksoft_dirty(pmd); 1064 if (pmd_swp_uffd_wp(*src_pmd)) 1065 pmd = pmd_swp_mkuffd_wp(pmd); 1066 set_pmd_at(src_mm, addr, src_pmd, pmd); 1067 } 1068 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1069 mm_inc_nr_ptes(dst_mm); 1070 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1071 if (!userfaultfd_wp(dst_vma)) 1072 pmd = pmd_swp_clear_uffd_wp(pmd); 1073 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1074 ret = 0; 1075 goto out_unlock; 1076 } 1077 #endif 1078 1079 if (unlikely(!pmd_trans_huge(pmd))) { 1080 pte_free(dst_mm, pgtable); 1081 goto out_unlock; 1082 } 1083 /* 1084 * When page table lock is held, the huge zero pmd should not be 1085 * under splitting since we don't split the page itself, only pmd to 1086 * a page table. 1087 */ 1088 if (is_huge_zero_pmd(pmd)) { 1089 /* 1090 * get_huge_zero_page() will never allocate a new page here, 1091 * since we already have a zero page to copy. It just takes a 1092 * reference. 1093 */ 1094 mm_get_huge_zero_page(dst_mm); 1095 goto out_zero_page; 1096 } 1097 1098 src_page = pmd_page(pmd); 1099 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1100 1101 get_page(src_page); 1102 if (unlikely(page_try_dup_anon_rmap(src_page, true, src_vma))) { 1103 /* Page maybe pinned: split and retry the fault on PTEs. */ 1104 put_page(src_page); 1105 pte_free(dst_mm, pgtable); 1106 spin_unlock(src_ptl); 1107 spin_unlock(dst_ptl); 1108 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL); 1109 return -EAGAIN; 1110 } 1111 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1112 out_zero_page: 1113 mm_inc_nr_ptes(dst_mm); 1114 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1115 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1116 if (!userfaultfd_wp(dst_vma)) 1117 pmd = pmd_clear_uffd_wp(pmd); 1118 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1119 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1120 1121 ret = 0; 1122 out_unlock: 1123 spin_unlock(src_ptl); 1124 spin_unlock(dst_ptl); 1125 out: 1126 return ret; 1127 } 1128 1129 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1130 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1131 pud_t *pud, int flags) 1132 { 1133 pud_t _pud; 1134 1135 _pud = pud_mkyoung(*pud); 1136 if (flags & FOLL_WRITE) 1137 _pud = pud_mkdirty(_pud); 1138 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1139 pud, _pud, flags & FOLL_WRITE)) 1140 update_mmu_cache_pud(vma, addr, pud); 1141 } 1142 1143 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1144 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1145 { 1146 unsigned long pfn = pud_pfn(*pud); 1147 struct mm_struct *mm = vma->vm_mm; 1148 struct page *page; 1149 1150 assert_spin_locked(pud_lockptr(mm, pud)); 1151 1152 if (flags & FOLL_WRITE && !pud_write(*pud)) 1153 return NULL; 1154 1155 /* FOLL_GET and FOLL_PIN are mutually exclusive. */ 1156 if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) == 1157 (FOLL_PIN | FOLL_GET))) 1158 return NULL; 1159 1160 if (pud_present(*pud) && pud_devmap(*pud)) 1161 /* pass */; 1162 else 1163 return NULL; 1164 1165 if (flags & FOLL_TOUCH) 1166 touch_pud(vma, addr, pud, flags); 1167 1168 /* 1169 * device mapped pages can only be returned if the 1170 * caller will manage the page reference count. 1171 * 1172 * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here: 1173 */ 1174 if (!(flags & (FOLL_GET | FOLL_PIN))) 1175 return ERR_PTR(-EEXIST); 1176 1177 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1178 *pgmap = get_dev_pagemap(pfn, *pgmap); 1179 if (!*pgmap) 1180 return ERR_PTR(-EFAULT); 1181 page = pfn_to_page(pfn); 1182 if (!try_grab_page(page, flags)) 1183 page = ERR_PTR(-ENOMEM); 1184 1185 return page; 1186 } 1187 1188 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1189 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1190 struct vm_area_struct *vma) 1191 { 1192 spinlock_t *dst_ptl, *src_ptl; 1193 pud_t pud; 1194 int ret; 1195 1196 dst_ptl = pud_lock(dst_mm, dst_pud); 1197 src_ptl = pud_lockptr(src_mm, src_pud); 1198 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1199 1200 ret = -EAGAIN; 1201 pud = *src_pud; 1202 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1203 goto out_unlock; 1204 1205 /* 1206 * When page table lock is held, the huge zero pud should not be 1207 * under splitting since we don't split the page itself, only pud to 1208 * a page table. 1209 */ 1210 if (is_huge_zero_pud(pud)) { 1211 /* No huge zero pud yet */ 1212 } 1213 1214 /* 1215 * TODO: once we support anonymous pages, use page_try_dup_anon_rmap() 1216 * and split if duplicating fails. 1217 */ 1218 pudp_set_wrprotect(src_mm, addr, src_pud); 1219 pud = pud_mkold(pud_wrprotect(pud)); 1220 set_pud_at(dst_mm, addr, dst_pud, pud); 1221 1222 ret = 0; 1223 out_unlock: 1224 spin_unlock(src_ptl); 1225 spin_unlock(dst_ptl); 1226 return ret; 1227 } 1228 1229 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1230 { 1231 pud_t entry; 1232 unsigned long haddr; 1233 bool write = vmf->flags & FAULT_FLAG_WRITE; 1234 1235 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1236 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1237 goto unlock; 1238 1239 entry = pud_mkyoung(orig_pud); 1240 if (write) 1241 entry = pud_mkdirty(entry); 1242 haddr = vmf->address & HPAGE_PUD_MASK; 1243 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) 1244 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); 1245 1246 unlock: 1247 spin_unlock(vmf->ptl); 1248 } 1249 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1250 1251 void huge_pmd_set_accessed(struct vm_fault *vmf) 1252 { 1253 pmd_t entry; 1254 unsigned long haddr; 1255 bool write = vmf->flags & FAULT_FLAG_WRITE; 1256 pmd_t orig_pmd = vmf->orig_pmd; 1257 1258 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1259 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1260 goto unlock; 1261 1262 entry = pmd_mkyoung(orig_pmd); 1263 if (write) 1264 entry = pmd_mkdirty(entry); 1265 haddr = vmf->address & HPAGE_PMD_MASK; 1266 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) 1267 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); 1268 1269 unlock: 1270 spin_unlock(vmf->ptl); 1271 } 1272 1273 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf) 1274 { 1275 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; 1276 struct vm_area_struct *vma = vmf->vma; 1277 struct page *page; 1278 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1279 pmd_t orig_pmd = vmf->orig_pmd; 1280 1281 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1282 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1283 1284 VM_BUG_ON(unshare && (vmf->flags & FAULT_FLAG_WRITE)); 1285 VM_BUG_ON(!unshare && !(vmf->flags & FAULT_FLAG_WRITE)); 1286 1287 if (is_huge_zero_pmd(orig_pmd)) 1288 goto fallback; 1289 1290 spin_lock(vmf->ptl); 1291 1292 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1293 spin_unlock(vmf->ptl); 1294 return 0; 1295 } 1296 1297 page = pmd_page(orig_pmd); 1298 VM_BUG_ON_PAGE(!PageHead(page), page); 1299 1300 /* Early check when only holding the PT lock. */ 1301 if (PageAnonExclusive(page)) 1302 goto reuse; 1303 1304 if (!trylock_page(page)) { 1305 get_page(page); 1306 spin_unlock(vmf->ptl); 1307 lock_page(page); 1308 spin_lock(vmf->ptl); 1309 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1310 spin_unlock(vmf->ptl); 1311 unlock_page(page); 1312 put_page(page); 1313 return 0; 1314 } 1315 put_page(page); 1316 } 1317 1318 /* Recheck after temporarily dropping the PT lock. */ 1319 if (PageAnonExclusive(page)) { 1320 unlock_page(page); 1321 goto reuse; 1322 } 1323 1324 /* 1325 * See do_wp_page(): we can only reuse the page exclusively if there are 1326 * no additional references. Note that we always drain the LRU 1327 * pagevecs immediately after adding a THP. 1328 */ 1329 if (page_count(page) > 1 + PageSwapCache(page) * thp_nr_pages(page)) 1330 goto unlock_fallback; 1331 if (PageSwapCache(page)) 1332 try_to_free_swap(page); 1333 if (page_count(page) == 1) { 1334 pmd_t entry; 1335 1336 page_move_anon_rmap(page, vma); 1337 unlock_page(page); 1338 reuse: 1339 if (unlikely(unshare)) { 1340 spin_unlock(vmf->ptl); 1341 return 0; 1342 } 1343 entry = pmd_mkyoung(orig_pmd); 1344 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1345 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1346 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1347 spin_unlock(vmf->ptl); 1348 return VM_FAULT_WRITE; 1349 } 1350 1351 unlock_fallback: 1352 unlock_page(page); 1353 spin_unlock(vmf->ptl); 1354 fallback: 1355 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL); 1356 return VM_FAULT_FALLBACK; 1357 } 1358 1359 /* 1360 * FOLL_FORCE can write to even unwritable pmd's, but only 1361 * after we've gone through a COW cycle and they are dirty. 1362 */ 1363 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) 1364 { 1365 return pmd_write(pmd) || 1366 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); 1367 } 1368 1369 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1370 unsigned long addr, 1371 pmd_t *pmd, 1372 unsigned int flags) 1373 { 1374 struct mm_struct *mm = vma->vm_mm; 1375 struct page *page = NULL; 1376 1377 assert_spin_locked(pmd_lockptr(mm, pmd)); 1378 1379 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) 1380 goto out; 1381 1382 /* Avoid dumping huge zero page */ 1383 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1384 return ERR_PTR(-EFAULT); 1385 1386 /* Full NUMA hinting faults to serialise migration in fault paths */ 1387 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) 1388 goto out; 1389 1390 page = pmd_page(*pmd); 1391 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1392 1393 if (!pmd_write(*pmd) && gup_must_unshare(flags, page)) 1394 return ERR_PTR(-EMLINK); 1395 1396 VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) && 1397 !PageAnonExclusive(page), page); 1398 1399 if (!try_grab_page(page, flags)) 1400 return ERR_PTR(-ENOMEM); 1401 1402 if (flags & FOLL_TOUCH) 1403 touch_pmd(vma, addr, pmd, flags); 1404 1405 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1406 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1407 1408 out: 1409 return page; 1410 } 1411 1412 /* NUMA hinting page fault entry point for trans huge pmds */ 1413 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf) 1414 { 1415 struct vm_area_struct *vma = vmf->vma; 1416 pmd_t oldpmd = vmf->orig_pmd; 1417 pmd_t pmd; 1418 struct page *page; 1419 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1420 int page_nid = NUMA_NO_NODE; 1421 int target_nid, last_cpupid = -1; 1422 bool migrated = false; 1423 bool was_writable = pmd_savedwrite(oldpmd); 1424 int flags = 0; 1425 1426 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1427 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1428 spin_unlock(vmf->ptl); 1429 goto out; 1430 } 1431 1432 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1433 page = vm_normal_page_pmd(vma, haddr, pmd); 1434 if (!page) 1435 goto out_map; 1436 1437 /* See similar comment in do_numa_page for explanation */ 1438 if (!was_writable) 1439 flags |= TNF_NO_GROUP; 1440 1441 page_nid = page_to_nid(page); 1442 last_cpupid = page_cpupid_last(page); 1443 target_nid = numa_migrate_prep(page, vma, haddr, page_nid, 1444 &flags); 1445 1446 if (target_nid == NUMA_NO_NODE) { 1447 put_page(page); 1448 goto out_map; 1449 } 1450 1451 spin_unlock(vmf->ptl); 1452 1453 migrated = migrate_misplaced_page(page, vma, target_nid); 1454 if (migrated) { 1455 flags |= TNF_MIGRATED; 1456 page_nid = target_nid; 1457 } else { 1458 flags |= TNF_MIGRATE_FAIL; 1459 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1460 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) { 1461 spin_unlock(vmf->ptl); 1462 goto out; 1463 } 1464 goto out_map; 1465 } 1466 1467 out: 1468 if (page_nid != NUMA_NO_NODE) 1469 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1470 flags); 1471 1472 return 0; 1473 1474 out_map: 1475 /* Restore the PMD */ 1476 pmd = pmd_modify(oldpmd, vma->vm_page_prot); 1477 pmd = pmd_mkyoung(pmd); 1478 if (was_writable) 1479 pmd = pmd_mkwrite(pmd); 1480 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1481 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1482 spin_unlock(vmf->ptl); 1483 goto out; 1484 } 1485 1486 /* 1487 * Return true if we do MADV_FREE successfully on entire pmd page. 1488 * Otherwise, return false. 1489 */ 1490 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1491 pmd_t *pmd, unsigned long addr, unsigned long next) 1492 { 1493 spinlock_t *ptl; 1494 pmd_t orig_pmd; 1495 struct page *page; 1496 struct mm_struct *mm = tlb->mm; 1497 bool ret = false; 1498 1499 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1500 1501 ptl = pmd_trans_huge_lock(pmd, vma); 1502 if (!ptl) 1503 goto out_unlocked; 1504 1505 orig_pmd = *pmd; 1506 if (is_huge_zero_pmd(orig_pmd)) 1507 goto out; 1508 1509 if (unlikely(!pmd_present(orig_pmd))) { 1510 VM_BUG_ON(thp_migration_supported() && 1511 !is_pmd_migration_entry(orig_pmd)); 1512 goto out; 1513 } 1514 1515 page = pmd_page(orig_pmd); 1516 /* 1517 * If other processes are mapping this page, we couldn't discard 1518 * the page unless they all do MADV_FREE so let's skip the page. 1519 */ 1520 if (total_mapcount(page) != 1) 1521 goto out; 1522 1523 if (!trylock_page(page)) 1524 goto out; 1525 1526 /* 1527 * If user want to discard part-pages of THP, split it so MADV_FREE 1528 * will deactivate only them. 1529 */ 1530 if (next - addr != HPAGE_PMD_SIZE) { 1531 get_page(page); 1532 spin_unlock(ptl); 1533 split_huge_page(page); 1534 unlock_page(page); 1535 put_page(page); 1536 goto out_unlocked; 1537 } 1538 1539 if (PageDirty(page)) 1540 ClearPageDirty(page); 1541 unlock_page(page); 1542 1543 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1544 pmdp_invalidate(vma, addr, pmd); 1545 orig_pmd = pmd_mkold(orig_pmd); 1546 orig_pmd = pmd_mkclean(orig_pmd); 1547 1548 set_pmd_at(mm, addr, pmd, orig_pmd); 1549 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1550 } 1551 1552 mark_page_lazyfree(page); 1553 ret = true; 1554 out: 1555 spin_unlock(ptl); 1556 out_unlocked: 1557 return ret; 1558 } 1559 1560 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1561 { 1562 pgtable_t pgtable; 1563 1564 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1565 pte_free(mm, pgtable); 1566 mm_dec_nr_ptes(mm); 1567 } 1568 1569 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1570 pmd_t *pmd, unsigned long addr) 1571 { 1572 pmd_t orig_pmd; 1573 spinlock_t *ptl; 1574 1575 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1576 1577 ptl = __pmd_trans_huge_lock(pmd, vma); 1578 if (!ptl) 1579 return 0; 1580 /* 1581 * For architectures like ppc64 we look at deposited pgtable 1582 * when calling pmdp_huge_get_and_clear. So do the 1583 * pgtable_trans_huge_withdraw after finishing pmdp related 1584 * operations. 1585 */ 1586 orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd, 1587 tlb->fullmm); 1588 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1589 if (vma_is_special_huge(vma)) { 1590 if (arch_needs_pgtable_deposit()) 1591 zap_deposited_table(tlb->mm, pmd); 1592 spin_unlock(ptl); 1593 } else if (is_huge_zero_pmd(orig_pmd)) { 1594 zap_deposited_table(tlb->mm, pmd); 1595 spin_unlock(ptl); 1596 } else { 1597 struct page *page = NULL; 1598 int flush_needed = 1; 1599 1600 if (pmd_present(orig_pmd)) { 1601 page = pmd_page(orig_pmd); 1602 page_remove_rmap(page, vma, true); 1603 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1604 VM_BUG_ON_PAGE(!PageHead(page), page); 1605 } else if (thp_migration_supported()) { 1606 swp_entry_t entry; 1607 1608 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1609 entry = pmd_to_swp_entry(orig_pmd); 1610 page = pfn_swap_entry_to_page(entry); 1611 flush_needed = 0; 1612 } else 1613 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1614 1615 if (PageAnon(page)) { 1616 zap_deposited_table(tlb->mm, pmd); 1617 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1618 } else { 1619 if (arch_needs_pgtable_deposit()) 1620 zap_deposited_table(tlb->mm, pmd); 1621 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1622 } 1623 1624 spin_unlock(ptl); 1625 if (flush_needed) 1626 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1627 } 1628 return 1; 1629 } 1630 1631 #ifndef pmd_move_must_withdraw 1632 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1633 spinlock_t *old_pmd_ptl, 1634 struct vm_area_struct *vma) 1635 { 1636 /* 1637 * With split pmd lock we also need to move preallocated 1638 * PTE page table if new_pmd is on different PMD page table. 1639 * 1640 * We also don't deposit and withdraw tables for file pages. 1641 */ 1642 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1643 } 1644 #endif 1645 1646 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1647 { 1648 #ifdef CONFIG_MEM_SOFT_DIRTY 1649 if (unlikely(is_pmd_migration_entry(pmd))) 1650 pmd = pmd_swp_mksoft_dirty(pmd); 1651 else if (pmd_present(pmd)) 1652 pmd = pmd_mksoft_dirty(pmd); 1653 #endif 1654 return pmd; 1655 } 1656 1657 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1658 unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) 1659 { 1660 spinlock_t *old_ptl, *new_ptl; 1661 pmd_t pmd; 1662 struct mm_struct *mm = vma->vm_mm; 1663 bool force_flush = false; 1664 1665 /* 1666 * The destination pmd shouldn't be established, free_pgtables() 1667 * should have release it. 1668 */ 1669 if (WARN_ON(!pmd_none(*new_pmd))) { 1670 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1671 return false; 1672 } 1673 1674 /* 1675 * We don't have to worry about the ordering of src and dst 1676 * ptlocks because exclusive mmap_lock prevents deadlock. 1677 */ 1678 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1679 if (old_ptl) { 1680 new_ptl = pmd_lockptr(mm, new_pmd); 1681 if (new_ptl != old_ptl) 1682 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1683 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1684 if (pmd_present(pmd)) 1685 force_flush = true; 1686 VM_BUG_ON(!pmd_none(*new_pmd)); 1687 1688 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1689 pgtable_t pgtable; 1690 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1691 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1692 } 1693 pmd = move_soft_dirty_pmd(pmd); 1694 set_pmd_at(mm, new_addr, new_pmd, pmd); 1695 if (force_flush) 1696 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1697 if (new_ptl != old_ptl) 1698 spin_unlock(new_ptl); 1699 spin_unlock(old_ptl); 1700 return true; 1701 } 1702 return false; 1703 } 1704 1705 /* 1706 * Returns 1707 * - 0 if PMD could not be locked 1708 * - 1 if PMD was locked but protections unchanged and TLB flush unnecessary 1709 * or if prot_numa but THP migration is not supported 1710 * - HPAGE_PMD_NR if protections changed and TLB flush necessary 1711 */ 1712 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1713 pmd_t *pmd, unsigned long addr, pgprot_t newprot, 1714 unsigned long cp_flags) 1715 { 1716 struct mm_struct *mm = vma->vm_mm; 1717 spinlock_t *ptl; 1718 pmd_t oldpmd, entry; 1719 bool preserve_write; 1720 int ret; 1721 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 1722 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 1723 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 1724 1725 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1726 1727 if (prot_numa && !thp_migration_supported()) 1728 return 1; 1729 1730 ptl = __pmd_trans_huge_lock(pmd, vma); 1731 if (!ptl) 1732 return 0; 1733 1734 preserve_write = prot_numa && pmd_write(*pmd); 1735 ret = 1; 1736 1737 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1738 if (is_swap_pmd(*pmd)) { 1739 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1740 struct page *page = pfn_swap_entry_to_page(entry); 1741 1742 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1743 if (is_writable_migration_entry(entry)) { 1744 pmd_t newpmd; 1745 /* 1746 * A protection check is difficult so 1747 * just be safe and disable write 1748 */ 1749 if (PageAnon(page)) 1750 entry = make_readable_exclusive_migration_entry(swp_offset(entry)); 1751 else 1752 entry = make_readable_migration_entry(swp_offset(entry)); 1753 newpmd = swp_entry_to_pmd(entry); 1754 if (pmd_swp_soft_dirty(*pmd)) 1755 newpmd = pmd_swp_mksoft_dirty(newpmd); 1756 if (pmd_swp_uffd_wp(*pmd)) 1757 newpmd = pmd_swp_mkuffd_wp(newpmd); 1758 set_pmd_at(mm, addr, pmd, newpmd); 1759 } 1760 goto unlock; 1761 } 1762 #endif 1763 1764 if (prot_numa) { 1765 struct page *page; 1766 /* 1767 * Avoid trapping faults against the zero page. The read-only 1768 * data is likely to be read-cached on the local CPU and 1769 * local/remote hits to the zero page are not interesting. 1770 */ 1771 if (is_huge_zero_pmd(*pmd)) 1772 goto unlock; 1773 1774 if (pmd_protnone(*pmd)) 1775 goto unlock; 1776 1777 page = pmd_page(*pmd); 1778 /* 1779 * Skip scanning top tier node if normal numa 1780 * balancing is disabled 1781 */ 1782 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 1783 node_is_toptier(page_to_nid(page))) 1784 goto unlock; 1785 } 1786 /* 1787 * In case prot_numa, we are under mmap_read_lock(mm). It's critical 1788 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1789 * which is also under mmap_read_lock(mm): 1790 * 1791 * CPU0: CPU1: 1792 * change_huge_pmd(prot_numa=1) 1793 * pmdp_huge_get_and_clear_notify() 1794 * madvise_dontneed() 1795 * zap_pmd_range() 1796 * pmd_trans_huge(*pmd) == 0 (without ptl) 1797 * // skip the pmd 1798 * set_pmd_at(); 1799 * // pmd is re-established 1800 * 1801 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1802 * which may break userspace. 1803 * 1804 * pmdp_invalidate_ad() is required to make sure we don't miss 1805 * dirty/young flags set by hardware. 1806 */ 1807 oldpmd = pmdp_invalidate_ad(vma, addr, pmd); 1808 1809 entry = pmd_modify(oldpmd, newprot); 1810 if (preserve_write) 1811 entry = pmd_mk_savedwrite(entry); 1812 if (uffd_wp) { 1813 entry = pmd_wrprotect(entry); 1814 entry = pmd_mkuffd_wp(entry); 1815 } else if (uffd_wp_resolve) { 1816 /* 1817 * Leave the write bit to be handled by PF interrupt 1818 * handler, then things like COW could be properly 1819 * handled. 1820 */ 1821 entry = pmd_clear_uffd_wp(entry); 1822 } 1823 ret = HPAGE_PMD_NR; 1824 set_pmd_at(mm, addr, pmd, entry); 1825 1826 if (huge_pmd_needs_flush(oldpmd, entry)) 1827 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE); 1828 1829 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); 1830 unlock: 1831 spin_unlock(ptl); 1832 return ret; 1833 } 1834 1835 /* 1836 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 1837 * 1838 * Note that if it returns page table lock pointer, this routine returns without 1839 * unlocking page table lock. So callers must unlock it. 1840 */ 1841 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 1842 { 1843 spinlock_t *ptl; 1844 ptl = pmd_lock(vma->vm_mm, pmd); 1845 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 1846 pmd_devmap(*pmd))) 1847 return ptl; 1848 spin_unlock(ptl); 1849 return NULL; 1850 } 1851 1852 /* 1853 * Returns true if a given pud maps a thp, false otherwise. 1854 * 1855 * Note that if it returns true, this routine returns without unlocking page 1856 * table lock. So callers must unlock it. 1857 */ 1858 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 1859 { 1860 spinlock_t *ptl; 1861 1862 ptl = pud_lock(vma->vm_mm, pud); 1863 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 1864 return ptl; 1865 spin_unlock(ptl); 1866 return NULL; 1867 } 1868 1869 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1870 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 1871 pud_t *pud, unsigned long addr) 1872 { 1873 spinlock_t *ptl; 1874 1875 ptl = __pud_trans_huge_lock(pud, vma); 1876 if (!ptl) 1877 return 0; 1878 /* 1879 * For architectures like ppc64 we look at deposited pgtable 1880 * when calling pudp_huge_get_and_clear. So do the 1881 * pgtable_trans_huge_withdraw after finishing pudp related 1882 * operations. 1883 */ 1884 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 1885 tlb_remove_pud_tlb_entry(tlb, pud, addr); 1886 if (vma_is_special_huge(vma)) { 1887 spin_unlock(ptl); 1888 /* No zero page support yet */ 1889 } else { 1890 /* No support for anonymous PUD pages yet */ 1891 BUG(); 1892 } 1893 return 1; 1894 } 1895 1896 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 1897 unsigned long haddr) 1898 { 1899 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 1900 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 1901 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 1902 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 1903 1904 count_vm_event(THP_SPLIT_PUD); 1905 1906 pudp_huge_clear_flush_notify(vma, haddr, pud); 1907 } 1908 1909 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 1910 unsigned long address) 1911 { 1912 spinlock_t *ptl; 1913 struct mmu_notifier_range range; 1914 1915 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1916 address & HPAGE_PUD_MASK, 1917 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 1918 mmu_notifier_invalidate_range_start(&range); 1919 ptl = pud_lock(vma->vm_mm, pud); 1920 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 1921 goto out; 1922 __split_huge_pud_locked(vma, pud, range.start); 1923 1924 out: 1925 spin_unlock(ptl); 1926 /* 1927 * No need to double call mmu_notifier->invalidate_range() callback as 1928 * the above pudp_huge_clear_flush_notify() did already call it. 1929 */ 1930 mmu_notifier_invalidate_range_only_end(&range); 1931 } 1932 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1933 1934 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 1935 unsigned long haddr, pmd_t *pmd) 1936 { 1937 struct mm_struct *mm = vma->vm_mm; 1938 pgtable_t pgtable; 1939 pmd_t _pmd; 1940 int i; 1941 1942 /* 1943 * Leave pmd empty until pte is filled note that it is fine to delay 1944 * notification until mmu_notifier_invalidate_range_end() as we are 1945 * replacing a zero pmd write protected page with a zero pte write 1946 * protected page. 1947 * 1948 * See Documentation/vm/mmu_notifier.rst 1949 */ 1950 pmdp_huge_clear_flush(vma, haddr, pmd); 1951 1952 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1953 pmd_populate(mm, &_pmd, pgtable); 1954 1955 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 1956 pte_t *pte, entry; 1957 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 1958 entry = pte_mkspecial(entry); 1959 pte = pte_offset_map(&_pmd, haddr); 1960 VM_BUG_ON(!pte_none(*pte)); 1961 set_pte_at(mm, haddr, pte, entry); 1962 pte_unmap(pte); 1963 } 1964 smp_wmb(); /* make pte visible before pmd */ 1965 pmd_populate(mm, pmd, pgtable); 1966 } 1967 1968 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 1969 unsigned long haddr, bool freeze) 1970 { 1971 struct mm_struct *mm = vma->vm_mm; 1972 struct page *page; 1973 pgtable_t pgtable; 1974 pmd_t old_pmd, _pmd; 1975 bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false; 1976 bool anon_exclusive = false; 1977 unsigned long addr; 1978 int i; 1979 1980 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 1981 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 1982 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 1983 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 1984 && !pmd_devmap(*pmd)); 1985 1986 count_vm_event(THP_SPLIT_PMD); 1987 1988 if (!vma_is_anonymous(vma)) { 1989 old_pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 1990 /* 1991 * We are going to unmap this huge page. So 1992 * just go ahead and zap it 1993 */ 1994 if (arch_needs_pgtable_deposit()) 1995 zap_deposited_table(mm, pmd); 1996 if (vma_is_special_huge(vma)) 1997 return; 1998 if (unlikely(is_pmd_migration_entry(old_pmd))) { 1999 swp_entry_t entry; 2000 2001 entry = pmd_to_swp_entry(old_pmd); 2002 page = pfn_swap_entry_to_page(entry); 2003 } else { 2004 page = pmd_page(old_pmd); 2005 if (!PageDirty(page) && pmd_dirty(old_pmd)) 2006 set_page_dirty(page); 2007 if (!PageReferenced(page) && pmd_young(old_pmd)) 2008 SetPageReferenced(page); 2009 page_remove_rmap(page, vma, true); 2010 put_page(page); 2011 } 2012 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2013 return; 2014 } 2015 2016 if (is_huge_zero_pmd(*pmd)) { 2017 /* 2018 * FIXME: Do we want to invalidate secondary mmu by calling 2019 * mmu_notifier_invalidate_range() see comments below inside 2020 * __split_huge_pmd() ? 2021 * 2022 * We are going from a zero huge page write protected to zero 2023 * small page also write protected so it does not seems useful 2024 * to invalidate secondary mmu at this time. 2025 */ 2026 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2027 } 2028 2029 /* 2030 * Up to this point the pmd is present and huge and userland has the 2031 * whole access to the hugepage during the split (which happens in 2032 * place). If we overwrite the pmd with the not-huge version pointing 2033 * to the pte here (which of course we could if all CPUs were bug 2034 * free), userland could trigger a small page size TLB miss on the 2035 * small sized TLB while the hugepage TLB entry is still established in 2036 * the huge TLB. Some CPU doesn't like that. 2037 * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum 2038 * 383 on page 105. Intel should be safe but is also warns that it's 2039 * only safe if the permission and cache attributes of the two entries 2040 * loaded in the two TLB is identical (which should be the case here). 2041 * But it is generally safer to never allow small and huge TLB entries 2042 * for the same virtual address to be loaded simultaneously. So instead 2043 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2044 * current pmd notpresent (atomically because here the pmd_trans_huge 2045 * must remain set at all times on the pmd until the split is complete 2046 * for this pmd), then we flush the SMP TLB and finally we write the 2047 * non-huge version of the pmd entry with pmd_populate. 2048 */ 2049 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2050 2051 pmd_migration = is_pmd_migration_entry(old_pmd); 2052 if (unlikely(pmd_migration)) { 2053 swp_entry_t entry; 2054 2055 entry = pmd_to_swp_entry(old_pmd); 2056 page = pfn_swap_entry_to_page(entry); 2057 write = is_writable_migration_entry(entry); 2058 if (PageAnon(page)) 2059 anon_exclusive = is_readable_exclusive_migration_entry(entry); 2060 young = false; 2061 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2062 uffd_wp = pmd_swp_uffd_wp(old_pmd); 2063 } else { 2064 page = pmd_page(old_pmd); 2065 if (pmd_dirty(old_pmd)) 2066 SetPageDirty(page); 2067 write = pmd_write(old_pmd); 2068 young = pmd_young(old_pmd); 2069 soft_dirty = pmd_soft_dirty(old_pmd); 2070 uffd_wp = pmd_uffd_wp(old_pmd); 2071 2072 VM_BUG_ON_PAGE(!page_count(page), page); 2073 page_ref_add(page, HPAGE_PMD_NR - 1); 2074 2075 /* 2076 * Without "freeze", we'll simply split the PMD, propagating the 2077 * PageAnonExclusive() flag for each PTE by setting it for 2078 * each subpage -- no need to (temporarily) clear. 2079 * 2080 * With "freeze" we want to replace mapped pages by 2081 * migration entries right away. This is only possible if we 2082 * managed to clear PageAnonExclusive() -- see 2083 * set_pmd_migration_entry(). 2084 * 2085 * In case we cannot clear PageAnonExclusive(), split the PMD 2086 * only and let try_to_migrate_one() fail later. 2087 */ 2088 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 2089 if (freeze && anon_exclusive && page_try_share_anon_rmap(page)) 2090 freeze = false; 2091 } 2092 2093 /* 2094 * Withdraw the table only after we mark the pmd entry invalid. 2095 * This's critical for some architectures (Power). 2096 */ 2097 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2098 pmd_populate(mm, &_pmd, pgtable); 2099 2100 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2101 pte_t entry, *pte; 2102 /* 2103 * Note that NUMA hinting access restrictions are not 2104 * transferred to avoid any possibility of altering 2105 * permissions across VMAs. 2106 */ 2107 if (freeze || pmd_migration) { 2108 swp_entry_t swp_entry; 2109 if (write) 2110 swp_entry = make_writable_migration_entry( 2111 page_to_pfn(page + i)); 2112 else if (anon_exclusive) 2113 swp_entry = make_readable_exclusive_migration_entry( 2114 page_to_pfn(page + i)); 2115 else 2116 swp_entry = make_readable_migration_entry( 2117 page_to_pfn(page + i)); 2118 entry = swp_entry_to_pte(swp_entry); 2119 if (soft_dirty) 2120 entry = pte_swp_mksoft_dirty(entry); 2121 if (uffd_wp) 2122 entry = pte_swp_mkuffd_wp(entry); 2123 } else { 2124 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2125 entry = maybe_mkwrite(entry, vma); 2126 if (anon_exclusive) 2127 SetPageAnonExclusive(page + i); 2128 if (!write) 2129 entry = pte_wrprotect(entry); 2130 if (!young) 2131 entry = pte_mkold(entry); 2132 if (soft_dirty) 2133 entry = pte_mksoft_dirty(entry); 2134 if (uffd_wp) 2135 entry = pte_mkuffd_wp(entry); 2136 } 2137 pte = pte_offset_map(&_pmd, addr); 2138 BUG_ON(!pte_none(*pte)); 2139 set_pte_at(mm, addr, pte, entry); 2140 if (!pmd_migration) 2141 atomic_inc(&page[i]._mapcount); 2142 pte_unmap(pte); 2143 } 2144 2145 if (!pmd_migration) { 2146 /* 2147 * Set PG_double_map before dropping compound_mapcount to avoid 2148 * false-negative page_mapped(). 2149 */ 2150 if (compound_mapcount(page) > 1 && 2151 !TestSetPageDoubleMap(page)) { 2152 for (i = 0; i < HPAGE_PMD_NR; i++) 2153 atomic_inc(&page[i]._mapcount); 2154 } 2155 2156 lock_page_memcg(page); 2157 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { 2158 /* Last compound_mapcount is gone. */ 2159 __mod_lruvec_page_state(page, NR_ANON_THPS, 2160 -HPAGE_PMD_NR); 2161 if (TestClearPageDoubleMap(page)) { 2162 /* No need in mapcount reference anymore */ 2163 for (i = 0; i < HPAGE_PMD_NR; i++) 2164 atomic_dec(&page[i]._mapcount); 2165 } 2166 } 2167 unlock_page_memcg(page); 2168 2169 /* Above is effectively page_remove_rmap(page, vma, true) */ 2170 munlock_vma_page(page, vma, true); 2171 } 2172 2173 smp_wmb(); /* make pte visible before pmd */ 2174 pmd_populate(mm, pmd, pgtable); 2175 2176 if (freeze) { 2177 for (i = 0; i < HPAGE_PMD_NR; i++) { 2178 page_remove_rmap(page + i, vma, false); 2179 put_page(page + i); 2180 } 2181 } 2182 } 2183 2184 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2185 unsigned long address, bool freeze, struct folio *folio) 2186 { 2187 spinlock_t *ptl; 2188 struct mmu_notifier_range range; 2189 2190 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2191 address & HPAGE_PMD_MASK, 2192 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2193 mmu_notifier_invalidate_range_start(&range); 2194 ptl = pmd_lock(vma->vm_mm, pmd); 2195 2196 /* 2197 * If caller asks to setup a migration entry, we need a folio to check 2198 * pmd against. Otherwise we can end up replacing wrong folio. 2199 */ 2200 VM_BUG_ON(freeze && !folio); 2201 VM_WARN_ON_ONCE(folio && !folio_test_locked(folio)); 2202 2203 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) || 2204 is_pmd_migration_entry(*pmd)) { 2205 if (folio && folio != page_folio(pmd_page(*pmd))) 2206 goto out; 2207 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2208 } 2209 2210 out: 2211 spin_unlock(ptl); 2212 /* 2213 * No need to double call mmu_notifier->invalidate_range() callback. 2214 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2215 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2216 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2217 * fault will trigger a flush_notify before pointing to a new page 2218 * (it is fine if the secondary mmu keeps pointing to the old zero 2219 * page in the meantime) 2220 * 3) Split a huge pmd into pte pointing to the same page. No need 2221 * to invalidate secondary tlb entry they are all still valid. 2222 * any further changes to individual pte will notify. So no need 2223 * to call mmu_notifier->invalidate_range() 2224 */ 2225 mmu_notifier_invalidate_range_only_end(&range); 2226 } 2227 2228 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2229 bool freeze, struct folio *folio) 2230 { 2231 pgd_t *pgd; 2232 p4d_t *p4d; 2233 pud_t *pud; 2234 pmd_t *pmd; 2235 2236 pgd = pgd_offset(vma->vm_mm, address); 2237 if (!pgd_present(*pgd)) 2238 return; 2239 2240 p4d = p4d_offset(pgd, address); 2241 if (!p4d_present(*p4d)) 2242 return; 2243 2244 pud = pud_offset(p4d, address); 2245 if (!pud_present(*pud)) 2246 return; 2247 2248 pmd = pmd_offset(pud, address); 2249 2250 __split_huge_pmd(vma, pmd, address, freeze, folio); 2251 } 2252 2253 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address) 2254 { 2255 /* 2256 * If the new address isn't hpage aligned and it could previously 2257 * contain an hugepage: check if we need to split an huge pmd. 2258 */ 2259 if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) && 2260 range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE), 2261 ALIGN(address, HPAGE_PMD_SIZE))) 2262 split_huge_pmd_address(vma, address, false, NULL); 2263 } 2264 2265 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2266 unsigned long start, 2267 unsigned long end, 2268 long adjust_next) 2269 { 2270 /* Check if we need to split start first. */ 2271 split_huge_pmd_if_needed(vma, start); 2272 2273 /* Check if we need to split end next. */ 2274 split_huge_pmd_if_needed(vma, end); 2275 2276 /* 2277 * If we're also updating the vma->vm_next->vm_start, 2278 * check if we need to split it. 2279 */ 2280 if (adjust_next > 0) { 2281 struct vm_area_struct *next = vma->vm_next; 2282 unsigned long nstart = next->vm_start; 2283 nstart += adjust_next; 2284 split_huge_pmd_if_needed(next, nstart); 2285 } 2286 } 2287 2288 static void unmap_page(struct page *page) 2289 { 2290 struct folio *folio = page_folio(page); 2291 enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | 2292 TTU_SYNC; 2293 2294 VM_BUG_ON_PAGE(!PageHead(page), page); 2295 2296 /* 2297 * Anon pages need migration entries to preserve them, but file 2298 * pages can simply be left unmapped, then faulted back on demand. 2299 * If that is ever changed (perhaps for mlock), update remap_page(). 2300 */ 2301 if (folio_test_anon(folio)) 2302 try_to_migrate(folio, ttu_flags); 2303 else 2304 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK); 2305 } 2306 2307 static void remap_page(struct folio *folio, unsigned long nr) 2308 { 2309 int i = 0; 2310 2311 /* If unmap_page() uses try_to_migrate() on file, remove this check */ 2312 if (!folio_test_anon(folio)) 2313 return; 2314 for (;;) { 2315 remove_migration_ptes(folio, folio, true); 2316 i += folio_nr_pages(folio); 2317 if (i >= nr) 2318 break; 2319 folio = folio_next(folio); 2320 } 2321 } 2322 2323 static void lru_add_page_tail(struct page *head, struct page *tail, 2324 struct lruvec *lruvec, struct list_head *list) 2325 { 2326 VM_BUG_ON_PAGE(!PageHead(head), head); 2327 VM_BUG_ON_PAGE(PageCompound(tail), head); 2328 VM_BUG_ON_PAGE(PageLRU(tail), head); 2329 lockdep_assert_held(&lruvec->lru_lock); 2330 2331 if (list) { 2332 /* page reclaim is reclaiming a huge page */ 2333 VM_WARN_ON(PageLRU(head)); 2334 get_page(tail); 2335 list_add_tail(&tail->lru, list); 2336 } else { 2337 /* head is still on lru (and we have it frozen) */ 2338 VM_WARN_ON(!PageLRU(head)); 2339 if (PageUnevictable(tail)) 2340 tail->mlock_count = 0; 2341 else 2342 list_add_tail(&tail->lru, &head->lru); 2343 SetPageLRU(tail); 2344 } 2345 } 2346 2347 static void __split_huge_page_tail(struct page *head, int tail, 2348 struct lruvec *lruvec, struct list_head *list) 2349 { 2350 struct page *page_tail = head + tail; 2351 2352 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2353 2354 /* 2355 * Clone page flags before unfreezing refcount. 2356 * 2357 * After successful get_page_unless_zero() might follow flags change, 2358 * for example lock_page() which set PG_waiters. 2359 * 2360 * Note that for mapped sub-pages of an anonymous THP, 2361 * PG_anon_exclusive has been cleared in unmap_page() and is stored in 2362 * the migration entry instead from where remap_page() will restore it. 2363 * We can still have PG_anon_exclusive set on effectively unmapped and 2364 * unreferenced sub-pages of an anonymous THP: we can simply drop 2365 * PG_anon_exclusive (-> PG_mappedtodisk) for these here. 2366 */ 2367 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2368 page_tail->flags |= (head->flags & 2369 ((1L << PG_referenced) | 2370 (1L << PG_swapbacked) | 2371 (1L << PG_swapcache) | 2372 (1L << PG_mlocked) | 2373 (1L << PG_uptodate) | 2374 (1L << PG_active) | 2375 (1L << PG_workingset) | 2376 (1L << PG_locked) | 2377 (1L << PG_unevictable) | 2378 #ifdef CONFIG_64BIT 2379 (1L << PG_arch_2) | 2380 #endif 2381 (1L << PG_dirty))); 2382 2383 /* ->mapping in first tail page is compound_mapcount */ 2384 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2385 page_tail); 2386 page_tail->mapping = head->mapping; 2387 page_tail->index = head->index + tail; 2388 2389 /* Page flags must be visible before we make the page non-compound. */ 2390 smp_wmb(); 2391 2392 /* 2393 * Clear PageTail before unfreezing page refcount. 2394 * 2395 * After successful get_page_unless_zero() might follow put_page() 2396 * which needs correct compound_head(). 2397 */ 2398 clear_compound_head(page_tail); 2399 2400 /* Finally unfreeze refcount. Additional reference from page cache. */ 2401 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2402 PageSwapCache(head))); 2403 2404 if (page_is_young(head)) 2405 set_page_young(page_tail); 2406 if (page_is_idle(head)) 2407 set_page_idle(page_tail); 2408 2409 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2410 2411 /* 2412 * always add to the tail because some iterators expect new 2413 * pages to show after the currently processed elements - e.g. 2414 * migrate_pages 2415 */ 2416 lru_add_page_tail(head, page_tail, lruvec, list); 2417 } 2418 2419 static void __split_huge_page(struct page *page, struct list_head *list, 2420 pgoff_t end) 2421 { 2422 struct folio *folio = page_folio(page); 2423 struct page *head = &folio->page; 2424 struct lruvec *lruvec; 2425 struct address_space *swap_cache = NULL; 2426 unsigned long offset = 0; 2427 unsigned int nr = thp_nr_pages(head); 2428 int i; 2429 2430 /* complete memcg works before add pages to LRU */ 2431 split_page_memcg(head, nr); 2432 2433 if (PageAnon(head) && PageSwapCache(head)) { 2434 swp_entry_t entry = { .val = page_private(head) }; 2435 2436 offset = swp_offset(entry); 2437 swap_cache = swap_address_space(entry); 2438 xa_lock(&swap_cache->i_pages); 2439 } 2440 2441 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */ 2442 lruvec = folio_lruvec_lock(folio); 2443 2444 ClearPageHasHWPoisoned(head); 2445 2446 for (i = nr - 1; i >= 1; i--) { 2447 __split_huge_page_tail(head, i, lruvec, list); 2448 /* Some pages can be beyond EOF: drop them from page cache */ 2449 if (head[i].index >= end) { 2450 ClearPageDirty(head + i); 2451 __delete_from_page_cache(head + i, NULL); 2452 if (shmem_mapping(head->mapping)) 2453 shmem_uncharge(head->mapping->host, 1); 2454 put_page(head + i); 2455 } else if (!PageAnon(page)) { 2456 __xa_store(&head->mapping->i_pages, head[i].index, 2457 head + i, 0); 2458 } else if (swap_cache) { 2459 __xa_store(&swap_cache->i_pages, offset + i, 2460 head + i, 0); 2461 } 2462 } 2463 2464 ClearPageCompound(head); 2465 unlock_page_lruvec(lruvec); 2466 /* Caller disabled irqs, so they are still disabled here */ 2467 2468 split_page_owner(head, nr); 2469 2470 /* See comment in __split_huge_page_tail() */ 2471 if (PageAnon(head)) { 2472 /* Additional pin to swap cache */ 2473 if (PageSwapCache(head)) { 2474 page_ref_add(head, 2); 2475 xa_unlock(&swap_cache->i_pages); 2476 } else { 2477 page_ref_inc(head); 2478 } 2479 } else { 2480 /* Additional pin to page cache */ 2481 page_ref_add(head, 2); 2482 xa_unlock(&head->mapping->i_pages); 2483 } 2484 local_irq_enable(); 2485 2486 remap_page(folio, nr); 2487 2488 if (PageSwapCache(head)) { 2489 swp_entry_t entry = { .val = page_private(head) }; 2490 2491 split_swap_cluster(entry); 2492 } 2493 2494 for (i = 0; i < nr; i++) { 2495 struct page *subpage = head + i; 2496 if (subpage == page) 2497 continue; 2498 unlock_page(subpage); 2499 2500 /* 2501 * Subpages may be freed if there wasn't any mapping 2502 * like if add_to_swap() is running on a lru page that 2503 * had its mapping zapped. And freeing these pages 2504 * requires taking the lru_lock so we do the put_page 2505 * of the tail pages after the split is complete. 2506 */ 2507 put_page(subpage); 2508 } 2509 } 2510 2511 /* Racy check whether the huge page can be split */ 2512 bool can_split_folio(struct folio *folio, int *pextra_pins) 2513 { 2514 int extra_pins; 2515 2516 /* Additional pins from page cache */ 2517 if (folio_test_anon(folio)) 2518 extra_pins = folio_test_swapcache(folio) ? 2519 folio_nr_pages(folio) : 0; 2520 else 2521 extra_pins = folio_nr_pages(folio); 2522 if (pextra_pins) 2523 *pextra_pins = extra_pins; 2524 return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1; 2525 } 2526 2527 /* 2528 * This function splits huge page into normal pages. @page can point to any 2529 * subpage of huge page to split. Split doesn't change the position of @page. 2530 * 2531 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2532 * The huge page must be locked. 2533 * 2534 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2535 * 2536 * Both head page and tail pages will inherit mapping, flags, and so on from 2537 * the hugepage. 2538 * 2539 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2540 * they are not mapped. 2541 * 2542 * Returns 0 if the hugepage is split successfully. 2543 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2544 * us. 2545 */ 2546 int split_huge_page_to_list(struct page *page, struct list_head *list) 2547 { 2548 struct folio *folio = page_folio(page); 2549 struct page *head = &folio->page; 2550 struct deferred_split *ds_queue = get_deferred_split_queue(head); 2551 XA_STATE(xas, &head->mapping->i_pages, head->index); 2552 struct anon_vma *anon_vma = NULL; 2553 struct address_space *mapping = NULL; 2554 int extra_pins, ret; 2555 pgoff_t end; 2556 2557 VM_BUG_ON_PAGE(is_huge_zero_page(head), head); 2558 VM_BUG_ON_PAGE(!PageLocked(head), head); 2559 VM_BUG_ON_PAGE(!PageCompound(head), head); 2560 2561 if (PageWriteback(head)) 2562 return -EBUSY; 2563 2564 if (PageAnon(head)) { 2565 /* 2566 * The caller does not necessarily hold an mmap_lock that would 2567 * prevent the anon_vma disappearing so we first we take a 2568 * reference to it and then lock the anon_vma for write. This 2569 * is similar to folio_lock_anon_vma_read except the write lock 2570 * is taken to serialise against parallel split or collapse 2571 * operations. 2572 */ 2573 anon_vma = page_get_anon_vma(head); 2574 if (!anon_vma) { 2575 ret = -EBUSY; 2576 goto out; 2577 } 2578 end = -1; 2579 mapping = NULL; 2580 anon_vma_lock_write(anon_vma); 2581 } else { 2582 mapping = head->mapping; 2583 2584 /* Truncated ? */ 2585 if (!mapping) { 2586 ret = -EBUSY; 2587 goto out; 2588 } 2589 2590 xas_split_alloc(&xas, head, compound_order(head), 2591 mapping_gfp_mask(mapping) & GFP_RECLAIM_MASK); 2592 if (xas_error(&xas)) { 2593 ret = xas_error(&xas); 2594 goto out; 2595 } 2596 2597 anon_vma = NULL; 2598 i_mmap_lock_read(mapping); 2599 2600 /* 2601 *__split_huge_page() may need to trim off pages beyond EOF: 2602 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2603 * which cannot be nested inside the page tree lock. So note 2604 * end now: i_size itself may be changed at any moment, but 2605 * head page lock is good enough to serialize the trimming. 2606 */ 2607 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2608 if (shmem_mapping(mapping)) 2609 end = shmem_fallocend(mapping->host, end); 2610 } 2611 2612 /* 2613 * Racy check if we can split the page, before unmap_page() will 2614 * split PMDs 2615 */ 2616 if (!can_split_folio(folio, &extra_pins)) { 2617 ret = -EBUSY; 2618 goto out_unlock; 2619 } 2620 2621 unmap_page(head); 2622 2623 /* block interrupt reentry in xa_lock and spinlock */ 2624 local_irq_disable(); 2625 if (mapping) { 2626 /* 2627 * Check if the head page is present in page cache. 2628 * We assume all tail are present too, if head is there. 2629 */ 2630 xas_lock(&xas); 2631 xas_reset(&xas); 2632 if (xas_load(&xas) != head) 2633 goto fail; 2634 } 2635 2636 /* Prevent deferred_split_scan() touching ->_refcount */ 2637 spin_lock(&ds_queue->split_queue_lock); 2638 if (page_ref_freeze(head, 1 + extra_pins)) { 2639 if (!list_empty(page_deferred_list(head))) { 2640 ds_queue->split_queue_len--; 2641 list_del(page_deferred_list(head)); 2642 } 2643 spin_unlock(&ds_queue->split_queue_lock); 2644 if (mapping) { 2645 int nr = thp_nr_pages(head); 2646 2647 xas_split(&xas, head, thp_order(head)); 2648 if (PageSwapBacked(head)) { 2649 __mod_lruvec_page_state(head, NR_SHMEM_THPS, 2650 -nr); 2651 } else { 2652 __mod_lruvec_page_state(head, NR_FILE_THPS, 2653 -nr); 2654 filemap_nr_thps_dec(mapping); 2655 } 2656 } 2657 2658 __split_huge_page(page, list, end); 2659 ret = 0; 2660 } else { 2661 spin_unlock(&ds_queue->split_queue_lock); 2662 fail: 2663 if (mapping) 2664 xas_unlock(&xas); 2665 local_irq_enable(); 2666 remap_page(folio, folio_nr_pages(folio)); 2667 ret = -EBUSY; 2668 } 2669 2670 out_unlock: 2671 if (anon_vma) { 2672 anon_vma_unlock_write(anon_vma); 2673 put_anon_vma(anon_vma); 2674 } 2675 if (mapping) 2676 i_mmap_unlock_read(mapping); 2677 out: 2678 /* Free any memory we didn't use */ 2679 xas_nomem(&xas, 0); 2680 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2681 return ret; 2682 } 2683 2684 void free_transhuge_page(struct page *page) 2685 { 2686 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2687 unsigned long flags; 2688 2689 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2690 if (!list_empty(page_deferred_list(page))) { 2691 ds_queue->split_queue_len--; 2692 list_del(page_deferred_list(page)); 2693 } 2694 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2695 free_compound_page(page); 2696 } 2697 2698 void deferred_split_huge_page(struct page *page) 2699 { 2700 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2701 #ifdef CONFIG_MEMCG 2702 struct mem_cgroup *memcg = page_memcg(compound_head(page)); 2703 #endif 2704 unsigned long flags; 2705 2706 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2707 2708 /* 2709 * The try_to_unmap() in page reclaim path might reach here too, 2710 * this may cause a race condition to corrupt deferred split queue. 2711 * And, if page reclaim is already handling the same page, it is 2712 * unnecessary to handle it again in shrinker. 2713 * 2714 * Check PageSwapCache to determine if the page is being 2715 * handled by page reclaim since THP swap would add the page into 2716 * swap cache before calling try_to_unmap(). 2717 */ 2718 if (PageSwapCache(page)) 2719 return; 2720 2721 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2722 if (list_empty(page_deferred_list(page))) { 2723 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2724 list_add_tail(page_deferred_list(page), &ds_queue->split_queue); 2725 ds_queue->split_queue_len++; 2726 #ifdef CONFIG_MEMCG 2727 if (memcg) 2728 set_shrinker_bit(memcg, page_to_nid(page), 2729 deferred_split_shrinker.id); 2730 #endif 2731 } 2732 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2733 } 2734 2735 static unsigned long deferred_split_count(struct shrinker *shrink, 2736 struct shrink_control *sc) 2737 { 2738 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2739 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2740 2741 #ifdef CONFIG_MEMCG 2742 if (sc->memcg) 2743 ds_queue = &sc->memcg->deferred_split_queue; 2744 #endif 2745 return READ_ONCE(ds_queue->split_queue_len); 2746 } 2747 2748 static unsigned long deferred_split_scan(struct shrinker *shrink, 2749 struct shrink_control *sc) 2750 { 2751 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2752 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2753 unsigned long flags; 2754 LIST_HEAD(list), *pos, *next; 2755 struct page *page; 2756 int split = 0; 2757 2758 #ifdef CONFIG_MEMCG 2759 if (sc->memcg) 2760 ds_queue = &sc->memcg->deferred_split_queue; 2761 #endif 2762 2763 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2764 /* Take pin on all head pages to avoid freeing them under us */ 2765 list_for_each_safe(pos, next, &ds_queue->split_queue) { 2766 page = list_entry((void *)pos, struct page, deferred_list); 2767 page = compound_head(page); 2768 if (get_page_unless_zero(page)) { 2769 list_move(page_deferred_list(page), &list); 2770 } else { 2771 /* We lost race with put_compound_page() */ 2772 list_del_init(page_deferred_list(page)); 2773 ds_queue->split_queue_len--; 2774 } 2775 if (!--sc->nr_to_scan) 2776 break; 2777 } 2778 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2779 2780 list_for_each_safe(pos, next, &list) { 2781 page = list_entry((void *)pos, struct page, deferred_list); 2782 if (!trylock_page(page)) 2783 goto next; 2784 /* split_huge_page() removes page from list on success */ 2785 if (!split_huge_page(page)) 2786 split++; 2787 unlock_page(page); 2788 next: 2789 put_page(page); 2790 } 2791 2792 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2793 list_splice_tail(&list, &ds_queue->split_queue); 2794 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2795 2796 /* 2797 * Stop shrinker if we didn't split any page, but the queue is empty. 2798 * This can happen if pages were freed under us. 2799 */ 2800 if (!split && list_empty(&ds_queue->split_queue)) 2801 return SHRINK_STOP; 2802 return split; 2803 } 2804 2805 static struct shrinker deferred_split_shrinker = { 2806 .count_objects = deferred_split_count, 2807 .scan_objects = deferred_split_scan, 2808 .seeks = DEFAULT_SEEKS, 2809 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | 2810 SHRINKER_NONSLAB, 2811 }; 2812 2813 #ifdef CONFIG_DEBUG_FS 2814 static void split_huge_pages_all(void) 2815 { 2816 struct zone *zone; 2817 struct page *page; 2818 unsigned long pfn, max_zone_pfn; 2819 unsigned long total = 0, split = 0; 2820 2821 pr_debug("Split all THPs\n"); 2822 for_each_populated_zone(zone) { 2823 max_zone_pfn = zone_end_pfn(zone); 2824 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2825 if (!pfn_valid(pfn)) 2826 continue; 2827 2828 page = pfn_to_page(pfn); 2829 if (!get_page_unless_zero(page)) 2830 continue; 2831 2832 if (zone != page_zone(page)) 2833 goto next; 2834 2835 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 2836 goto next; 2837 2838 total++; 2839 lock_page(page); 2840 if (!split_huge_page(page)) 2841 split++; 2842 unlock_page(page); 2843 next: 2844 put_page(page); 2845 cond_resched(); 2846 } 2847 } 2848 2849 pr_debug("%lu of %lu THP split\n", split, total); 2850 } 2851 2852 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma) 2853 { 2854 return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) || 2855 is_vm_hugetlb_page(vma); 2856 } 2857 2858 static int split_huge_pages_pid(int pid, unsigned long vaddr_start, 2859 unsigned long vaddr_end) 2860 { 2861 int ret = 0; 2862 struct task_struct *task; 2863 struct mm_struct *mm; 2864 unsigned long total = 0, split = 0; 2865 unsigned long addr; 2866 2867 vaddr_start &= PAGE_MASK; 2868 vaddr_end &= PAGE_MASK; 2869 2870 /* Find the task_struct from pid */ 2871 rcu_read_lock(); 2872 task = find_task_by_vpid(pid); 2873 if (!task) { 2874 rcu_read_unlock(); 2875 ret = -ESRCH; 2876 goto out; 2877 } 2878 get_task_struct(task); 2879 rcu_read_unlock(); 2880 2881 /* Find the mm_struct */ 2882 mm = get_task_mm(task); 2883 put_task_struct(task); 2884 2885 if (!mm) { 2886 ret = -EINVAL; 2887 goto out; 2888 } 2889 2890 pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n", 2891 pid, vaddr_start, vaddr_end); 2892 2893 mmap_read_lock(mm); 2894 /* 2895 * always increase addr by PAGE_SIZE, since we could have a PTE page 2896 * table filled with PTE-mapped THPs, each of which is distinct. 2897 */ 2898 for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) { 2899 struct vm_area_struct *vma = find_vma(mm, addr); 2900 struct page *page; 2901 2902 if (!vma || addr < vma->vm_start) 2903 break; 2904 2905 /* skip special VMA and hugetlb VMA */ 2906 if (vma_not_suitable_for_thp_split(vma)) { 2907 addr = vma->vm_end; 2908 continue; 2909 } 2910 2911 /* FOLL_DUMP to ignore special (like zero) pages */ 2912 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); 2913 2914 if (IS_ERR(page)) 2915 continue; 2916 if (!page) 2917 continue; 2918 2919 if (!is_transparent_hugepage(page)) 2920 goto next; 2921 2922 total++; 2923 if (!can_split_folio(page_folio(page), NULL)) 2924 goto next; 2925 2926 if (!trylock_page(page)) 2927 goto next; 2928 2929 if (!split_huge_page(page)) 2930 split++; 2931 2932 unlock_page(page); 2933 next: 2934 put_page(page); 2935 cond_resched(); 2936 } 2937 mmap_read_unlock(mm); 2938 mmput(mm); 2939 2940 pr_debug("%lu of %lu THP split\n", split, total); 2941 2942 out: 2943 return ret; 2944 } 2945 2946 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, 2947 pgoff_t off_end) 2948 { 2949 struct filename *file; 2950 struct file *candidate; 2951 struct address_space *mapping; 2952 int ret = -EINVAL; 2953 pgoff_t index; 2954 int nr_pages = 1; 2955 unsigned long total = 0, split = 0; 2956 2957 file = getname_kernel(file_path); 2958 if (IS_ERR(file)) 2959 return ret; 2960 2961 candidate = file_open_name(file, O_RDONLY, 0); 2962 if (IS_ERR(candidate)) 2963 goto out; 2964 2965 pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n", 2966 file_path, off_start, off_end); 2967 2968 mapping = candidate->f_mapping; 2969 2970 for (index = off_start; index < off_end; index += nr_pages) { 2971 struct page *fpage = pagecache_get_page(mapping, index, 2972 FGP_ENTRY | FGP_HEAD, 0); 2973 2974 nr_pages = 1; 2975 if (xa_is_value(fpage) || !fpage) 2976 continue; 2977 2978 if (!is_transparent_hugepage(fpage)) 2979 goto next; 2980 2981 total++; 2982 nr_pages = thp_nr_pages(fpage); 2983 2984 if (!trylock_page(fpage)) 2985 goto next; 2986 2987 if (!split_huge_page(fpage)) 2988 split++; 2989 2990 unlock_page(fpage); 2991 next: 2992 put_page(fpage); 2993 cond_resched(); 2994 } 2995 2996 filp_close(candidate, NULL); 2997 ret = 0; 2998 2999 pr_debug("%lu of %lu file-backed THP split\n", split, total); 3000 out: 3001 putname(file); 3002 return ret; 3003 } 3004 3005 #define MAX_INPUT_BUF_SZ 255 3006 3007 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf, 3008 size_t count, loff_t *ppops) 3009 { 3010 static DEFINE_MUTEX(split_debug_mutex); 3011 ssize_t ret; 3012 /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */ 3013 char input_buf[MAX_INPUT_BUF_SZ]; 3014 int pid; 3015 unsigned long vaddr_start, vaddr_end; 3016 3017 ret = mutex_lock_interruptible(&split_debug_mutex); 3018 if (ret) 3019 return ret; 3020 3021 ret = -EFAULT; 3022 3023 memset(input_buf, 0, MAX_INPUT_BUF_SZ); 3024 if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ))) 3025 goto out; 3026 3027 input_buf[MAX_INPUT_BUF_SZ - 1] = '\0'; 3028 3029 if (input_buf[0] == '/') { 3030 char *tok; 3031 char *buf = input_buf; 3032 char file_path[MAX_INPUT_BUF_SZ]; 3033 pgoff_t off_start = 0, off_end = 0; 3034 size_t input_len = strlen(input_buf); 3035 3036 tok = strsep(&buf, ","); 3037 if (tok) { 3038 strcpy(file_path, tok); 3039 } else { 3040 ret = -EINVAL; 3041 goto out; 3042 } 3043 3044 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end); 3045 if (ret != 2) { 3046 ret = -EINVAL; 3047 goto out; 3048 } 3049 ret = split_huge_pages_in_file(file_path, off_start, off_end); 3050 if (!ret) 3051 ret = input_len; 3052 3053 goto out; 3054 } 3055 3056 ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end); 3057 if (ret == 1 && pid == 1) { 3058 split_huge_pages_all(); 3059 ret = strlen(input_buf); 3060 goto out; 3061 } else if (ret != 3) { 3062 ret = -EINVAL; 3063 goto out; 3064 } 3065 3066 ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end); 3067 if (!ret) 3068 ret = strlen(input_buf); 3069 out: 3070 mutex_unlock(&split_debug_mutex); 3071 return ret; 3072 3073 } 3074 3075 static const struct file_operations split_huge_pages_fops = { 3076 .owner = THIS_MODULE, 3077 .write = split_huge_pages_write, 3078 .llseek = no_llseek, 3079 }; 3080 3081 static int __init split_huge_pages_debugfs(void) 3082 { 3083 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 3084 &split_huge_pages_fops); 3085 return 0; 3086 } 3087 late_initcall(split_huge_pages_debugfs); 3088 #endif 3089 3090 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 3091 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 3092 struct page *page) 3093 { 3094 struct vm_area_struct *vma = pvmw->vma; 3095 struct mm_struct *mm = vma->vm_mm; 3096 unsigned long address = pvmw->address; 3097 bool anon_exclusive; 3098 pmd_t pmdval; 3099 swp_entry_t entry; 3100 pmd_t pmdswp; 3101 3102 if (!(pvmw->pmd && !pvmw->pte)) 3103 return 0; 3104 3105 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 3106 pmdval = pmdp_invalidate(vma, address, pvmw->pmd); 3107 3108 anon_exclusive = PageAnon(page) && PageAnonExclusive(page); 3109 if (anon_exclusive && page_try_share_anon_rmap(page)) { 3110 set_pmd_at(mm, address, pvmw->pmd, pmdval); 3111 return -EBUSY; 3112 } 3113 3114 if (pmd_dirty(pmdval)) 3115 set_page_dirty(page); 3116 if (pmd_write(pmdval)) 3117 entry = make_writable_migration_entry(page_to_pfn(page)); 3118 else if (anon_exclusive) 3119 entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); 3120 else 3121 entry = make_readable_migration_entry(page_to_pfn(page)); 3122 pmdswp = swp_entry_to_pmd(entry); 3123 if (pmd_soft_dirty(pmdval)) 3124 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3125 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3126 page_remove_rmap(page, vma, true); 3127 put_page(page); 3128 trace_set_migration_pmd(address, pmd_val(pmdswp)); 3129 3130 return 0; 3131 } 3132 3133 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3134 { 3135 struct vm_area_struct *vma = pvmw->vma; 3136 struct mm_struct *mm = vma->vm_mm; 3137 unsigned long address = pvmw->address; 3138 unsigned long mmun_start = address & HPAGE_PMD_MASK; 3139 pmd_t pmde; 3140 swp_entry_t entry; 3141 3142 if (!(pvmw->pmd && !pvmw->pte)) 3143 return; 3144 3145 entry = pmd_to_swp_entry(*pvmw->pmd); 3146 get_page(new); 3147 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot)); 3148 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3149 pmde = pmd_mksoft_dirty(pmde); 3150 if (is_writable_migration_entry(entry)) 3151 pmde = maybe_pmd_mkwrite(pmde, vma); 3152 if (pmd_swp_uffd_wp(*pvmw->pmd)) 3153 pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde)); 3154 3155 if (PageAnon(new)) { 3156 rmap_t rmap_flags = RMAP_COMPOUND; 3157 3158 if (!is_readable_migration_entry(entry)) 3159 rmap_flags |= RMAP_EXCLUSIVE; 3160 3161 page_add_anon_rmap(new, vma, mmun_start, rmap_flags); 3162 } else { 3163 page_add_file_rmap(new, vma, true); 3164 } 3165 VM_BUG_ON(pmd_write(pmde) && PageAnon(new) && !PageAnonExclusive(new)); 3166 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde); 3167 3168 /* No need to invalidate - it was non-present before */ 3169 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3170 trace_remove_migration_pmd(address, pmd_val(pmde)); 3171 } 3172 #endif 3173