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/coredump.h> 11 #include <linux/sched/numa_balancing.h> 12 #include <linux/highmem.h> 13 #include <linux/hugetlb.h> 14 #include <linux/mmu_notifier.h> 15 #include <linux/rmap.h> 16 #include <linux/swap.h> 17 #include <linux/shrinker.h> 18 #include <linux/mm_inline.h> 19 #include <linux/swapops.h> 20 #include <linux/dax.h> 21 #include <linux/khugepaged.h> 22 #include <linux/freezer.h> 23 #include <linux/pfn_t.h> 24 #include <linux/mman.h> 25 #include <linux/memremap.h> 26 #include <linux/pagemap.h> 27 #include <linux/debugfs.h> 28 #include <linux/migrate.h> 29 #include <linux/hashtable.h> 30 #include <linux/userfaultfd_k.h> 31 #include <linux/page_idle.h> 32 #include <linux/shmem_fs.h> 33 #include <linux/oom.h> 34 #include <linux/numa.h> 35 #include <linux/page_owner.h> 36 37 #include <asm/tlb.h> 38 #include <asm/pgalloc.h> 39 #include "internal.h" 40 41 /* 42 * By default, transparent hugepage support is disabled in order to avoid 43 * risking an increased memory footprint for applications that are not 44 * guaranteed to benefit from it. When transparent hugepage support is 45 * enabled, it is for all mappings, and khugepaged scans all mappings. 46 * Defrag is invoked by khugepaged hugepage allocations and by page faults 47 * for all hugepage allocations. 48 */ 49 unsigned long transparent_hugepage_flags __read_mostly = 50 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS 51 (1<<TRANSPARENT_HUGEPAGE_FLAG)| 52 #endif 53 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE 54 (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)| 55 #endif 56 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)| 57 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)| 58 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 59 60 static struct shrinker deferred_split_shrinker; 61 62 static atomic_t huge_zero_refcount; 63 struct page *huge_zero_page __read_mostly; 64 65 bool transparent_hugepage_enabled(struct vm_area_struct *vma) 66 { 67 /* The addr is used to check if the vma size fits */ 68 unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE; 69 70 if (!transhuge_vma_suitable(vma, addr)) 71 return false; 72 if (vma_is_anonymous(vma)) 73 return __transparent_hugepage_enabled(vma); 74 if (vma_is_shmem(vma)) 75 return shmem_huge_enabled(vma); 76 77 return false; 78 } 79 80 static struct page *get_huge_zero_page(void) 81 { 82 struct page *zero_page; 83 retry: 84 if (likely(atomic_inc_not_zero(&huge_zero_refcount))) 85 return READ_ONCE(huge_zero_page); 86 87 zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE, 88 HPAGE_PMD_ORDER); 89 if (!zero_page) { 90 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED); 91 return NULL; 92 } 93 count_vm_event(THP_ZERO_PAGE_ALLOC); 94 preempt_disable(); 95 if (cmpxchg(&huge_zero_page, NULL, zero_page)) { 96 preempt_enable(); 97 __free_pages(zero_page, compound_order(zero_page)); 98 goto retry; 99 } 100 101 /* We take additional reference here. It will be put back by shrinker */ 102 atomic_set(&huge_zero_refcount, 2); 103 preempt_enable(); 104 return READ_ONCE(huge_zero_page); 105 } 106 107 static void put_huge_zero_page(void) 108 { 109 /* 110 * Counter should never go to zero here. Only shrinker can put 111 * last reference. 112 */ 113 BUG_ON(atomic_dec_and_test(&huge_zero_refcount)); 114 } 115 116 struct page *mm_get_huge_zero_page(struct mm_struct *mm) 117 { 118 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 119 return READ_ONCE(huge_zero_page); 120 121 if (!get_huge_zero_page()) 122 return NULL; 123 124 if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 125 put_huge_zero_page(); 126 127 return READ_ONCE(huge_zero_page); 128 } 129 130 void mm_put_huge_zero_page(struct mm_struct *mm) 131 { 132 if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags)) 133 put_huge_zero_page(); 134 } 135 136 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink, 137 struct shrink_control *sc) 138 { 139 /* we can free zero page only if last reference remains */ 140 return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0; 141 } 142 143 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, 144 struct shrink_control *sc) 145 { 146 if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { 147 struct page *zero_page = xchg(&huge_zero_page, NULL); 148 BUG_ON(zero_page == NULL); 149 __free_pages(zero_page, compound_order(zero_page)); 150 return HPAGE_PMD_NR; 151 } 152 153 return 0; 154 } 155 156 static struct shrinker huge_zero_page_shrinker = { 157 .count_objects = shrink_huge_zero_page_count, 158 .scan_objects = shrink_huge_zero_page_scan, 159 .seeks = DEFAULT_SEEKS, 160 }; 161 162 #ifdef CONFIG_SYSFS 163 static ssize_t enabled_show(struct kobject *kobj, 164 struct kobj_attribute *attr, char *buf) 165 { 166 if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags)) 167 return sprintf(buf, "[always] madvise never\n"); 168 else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags)) 169 return sprintf(buf, "always [madvise] never\n"); 170 else 171 return sprintf(buf, "always madvise [never]\n"); 172 } 173 174 static ssize_t enabled_store(struct kobject *kobj, 175 struct kobj_attribute *attr, 176 const char *buf, size_t count) 177 { 178 ssize_t ret = count; 179 180 if (!memcmp("always", buf, 181 min(sizeof("always")-1, count))) { 182 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 183 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 184 } else if (!memcmp("madvise", buf, 185 min(sizeof("madvise")-1, count))) { 186 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 187 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 188 } else if (!memcmp("never", buf, 189 min(sizeof("never")-1, count))) { 190 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); 191 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); 192 } else 193 ret = -EINVAL; 194 195 if (ret > 0) { 196 int err = start_stop_khugepaged(); 197 if (err) 198 ret = err; 199 } 200 return ret; 201 } 202 static struct kobj_attribute enabled_attr = 203 __ATTR(enabled, 0644, enabled_show, enabled_store); 204 205 ssize_t single_hugepage_flag_show(struct kobject *kobj, 206 struct kobj_attribute *attr, char *buf, 207 enum transparent_hugepage_flag flag) 208 { 209 return sprintf(buf, "%d\n", 210 !!test_bit(flag, &transparent_hugepage_flags)); 211 } 212 213 ssize_t single_hugepage_flag_store(struct kobject *kobj, 214 struct kobj_attribute *attr, 215 const char *buf, size_t count, 216 enum transparent_hugepage_flag flag) 217 { 218 unsigned long value; 219 int ret; 220 221 ret = kstrtoul(buf, 10, &value); 222 if (ret < 0) 223 return ret; 224 if (value > 1) 225 return -EINVAL; 226 227 if (value) 228 set_bit(flag, &transparent_hugepage_flags); 229 else 230 clear_bit(flag, &transparent_hugepage_flags); 231 232 return count; 233 } 234 235 static ssize_t defrag_show(struct kobject *kobj, 236 struct kobj_attribute *attr, char *buf) 237 { 238 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 239 return sprintf(buf, "[always] defer defer+madvise madvise never\n"); 240 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 241 return sprintf(buf, "always [defer] defer+madvise madvise never\n"); 242 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 243 return sprintf(buf, "always defer [defer+madvise] madvise never\n"); 244 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 245 return sprintf(buf, "always defer defer+madvise [madvise] never\n"); 246 return sprintf(buf, "always defer defer+madvise madvise [never]\n"); 247 } 248 249 static ssize_t defrag_store(struct kobject *kobj, 250 struct kobj_attribute *attr, 251 const char *buf, size_t count) 252 { 253 if (!memcmp("always", buf, 254 min(sizeof("always")-1, count))) { 255 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 256 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 257 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 258 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 259 } else if (!memcmp("defer+madvise", buf, 260 min(sizeof("defer+madvise")-1, count))) { 261 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 262 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 263 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 264 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 265 } else if (!memcmp("defer", buf, 266 min(sizeof("defer")-1, count))) { 267 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 268 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 269 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 270 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 271 } else if (!memcmp("madvise", buf, 272 min(sizeof("madvise")-1, count))) { 273 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 274 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 275 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 276 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 277 } else if (!memcmp("never", buf, 278 min(sizeof("never")-1, count))) { 279 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); 280 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); 281 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); 282 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); 283 } else 284 return -EINVAL; 285 286 return count; 287 } 288 static struct kobj_attribute defrag_attr = 289 __ATTR(defrag, 0644, defrag_show, defrag_store); 290 291 static ssize_t use_zero_page_show(struct kobject *kobj, 292 struct kobj_attribute *attr, char *buf) 293 { 294 return single_hugepage_flag_show(kobj, attr, buf, 295 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 296 } 297 static ssize_t use_zero_page_store(struct kobject *kobj, 298 struct kobj_attribute *attr, const char *buf, size_t count) 299 { 300 return single_hugepage_flag_store(kobj, attr, buf, count, 301 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG); 302 } 303 static struct kobj_attribute use_zero_page_attr = 304 __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store); 305 306 static ssize_t hpage_pmd_size_show(struct kobject *kobj, 307 struct kobj_attribute *attr, char *buf) 308 { 309 return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE); 310 } 311 static struct kobj_attribute hpage_pmd_size_attr = 312 __ATTR_RO(hpage_pmd_size); 313 314 #ifdef CONFIG_DEBUG_VM 315 static ssize_t debug_cow_show(struct kobject *kobj, 316 struct kobj_attribute *attr, char *buf) 317 { 318 return single_hugepage_flag_show(kobj, attr, buf, 319 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); 320 } 321 static ssize_t debug_cow_store(struct kobject *kobj, 322 struct kobj_attribute *attr, 323 const char *buf, size_t count) 324 { 325 return single_hugepage_flag_store(kobj, attr, buf, count, 326 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG); 327 } 328 static struct kobj_attribute debug_cow_attr = 329 __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store); 330 #endif /* CONFIG_DEBUG_VM */ 331 332 static struct attribute *hugepage_attr[] = { 333 &enabled_attr.attr, 334 &defrag_attr.attr, 335 &use_zero_page_attr.attr, 336 &hpage_pmd_size_attr.attr, 337 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) 338 &shmem_enabled_attr.attr, 339 #endif 340 #ifdef CONFIG_DEBUG_VM 341 &debug_cow_attr.attr, 342 #endif 343 NULL, 344 }; 345 346 static const struct attribute_group hugepage_attr_group = { 347 .attrs = hugepage_attr, 348 }; 349 350 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) 351 { 352 int err; 353 354 *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); 355 if (unlikely(!*hugepage_kobj)) { 356 pr_err("failed to create transparent hugepage kobject\n"); 357 return -ENOMEM; 358 } 359 360 err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group); 361 if (err) { 362 pr_err("failed to register transparent hugepage group\n"); 363 goto delete_obj; 364 } 365 366 err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group); 367 if (err) { 368 pr_err("failed to register transparent hugepage group\n"); 369 goto remove_hp_group; 370 } 371 372 return 0; 373 374 remove_hp_group: 375 sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group); 376 delete_obj: 377 kobject_put(*hugepage_kobj); 378 return err; 379 } 380 381 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj) 382 { 383 sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group); 384 sysfs_remove_group(hugepage_kobj, &hugepage_attr_group); 385 kobject_put(hugepage_kobj); 386 } 387 #else 388 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj) 389 { 390 return 0; 391 } 392 393 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj) 394 { 395 } 396 #endif /* CONFIG_SYSFS */ 397 398 static int __init hugepage_init(void) 399 { 400 int err; 401 struct kobject *hugepage_kobj; 402 403 if (!has_transparent_hugepage()) { 404 transparent_hugepage_flags = 0; 405 return -EINVAL; 406 } 407 408 /* 409 * hugepages can't be allocated by the buddy allocator 410 */ 411 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER); 412 /* 413 * we use page->mapping and page->index in second tail page 414 * as list_head: assuming THP order >= 2 415 */ 416 MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2); 417 418 err = hugepage_init_sysfs(&hugepage_kobj); 419 if (err) 420 goto err_sysfs; 421 422 err = khugepaged_init(); 423 if (err) 424 goto err_slab; 425 426 err = register_shrinker(&huge_zero_page_shrinker); 427 if (err) 428 goto err_hzp_shrinker; 429 err = register_shrinker(&deferred_split_shrinker); 430 if (err) 431 goto err_split_shrinker; 432 433 /* 434 * By default disable transparent hugepages on smaller systems, 435 * where the extra memory used could hurt more than TLB overhead 436 * is likely to save. The admin can still enable it through /sys. 437 */ 438 if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) { 439 transparent_hugepage_flags = 0; 440 return 0; 441 } 442 443 err = start_stop_khugepaged(); 444 if (err) 445 goto err_khugepaged; 446 447 return 0; 448 err_khugepaged: 449 unregister_shrinker(&deferred_split_shrinker); 450 err_split_shrinker: 451 unregister_shrinker(&huge_zero_page_shrinker); 452 err_hzp_shrinker: 453 khugepaged_destroy(); 454 err_slab: 455 hugepage_exit_sysfs(hugepage_kobj); 456 err_sysfs: 457 return err; 458 } 459 subsys_initcall(hugepage_init); 460 461 static int __init setup_transparent_hugepage(char *str) 462 { 463 int ret = 0; 464 if (!str) 465 goto out; 466 if (!strcmp(str, "always")) { 467 set_bit(TRANSPARENT_HUGEPAGE_FLAG, 468 &transparent_hugepage_flags); 469 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 470 &transparent_hugepage_flags); 471 ret = 1; 472 } else if (!strcmp(str, "madvise")) { 473 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 474 &transparent_hugepage_flags); 475 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 476 &transparent_hugepage_flags); 477 ret = 1; 478 } else if (!strcmp(str, "never")) { 479 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, 480 &transparent_hugepage_flags); 481 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, 482 &transparent_hugepage_flags); 483 ret = 1; 484 } 485 out: 486 if (!ret) 487 pr_warn("transparent_hugepage= cannot parse, ignored\n"); 488 return ret; 489 } 490 __setup("transparent_hugepage=", setup_transparent_hugepage); 491 492 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) 493 { 494 if (likely(vma->vm_flags & VM_WRITE)) 495 pmd = pmd_mkwrite(pmd); 496 return pmd; 497 } 498 499 static inline struct list_head *page_deferred_list(struct page *page) 500 { 501 /* ->lru in the tail pages is occupied by compound_head. */ 502 return &page[2].deferred_list; 503 } 504 505 void prep_transhuge_page(struct page *page) 506 { 507 /* 508 * we use page->mapping and page->indexlru in second tail page 509 * as list_head: assuming THP order >= 2 510 */ 511 512 INIT_LIST_HEAD(page_deferred_list(page)); 513 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); 514 } 515 516 static unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len, 517 loff_t off, unsigned long flags, unsigned long size) 518 { 519 unsigned long addr; 520 loff_t off_end = off + len; 521 loff_t off_align = round_up(off, size); 522 unsigned long len_pad; 523 524 if (off_end <= off_align || (off_end - off_align) < size) 525 return 0; 526 527 len_pad = len + size; 528 if (len_pad < len || (off + len_pad) < off) 529 return 0; 530 531 addr = current->mm->get_unmapped_area(filp, 0, len_pad, 532 off >> PAGE_SHIFT, flags); 533 if (IS_ERR_VALUE(addr)) 534 return 0; 535 536 addr += (off - addr) & (size - 1); 537 return addr; 538 } 539 540 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 541 unsigned long len, unsigned long pgoff, unsigned long flags) 542 { 543 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 544 545 if (addr) 546 goto out; 547 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD)) 548 goto out; 549 550 addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE); 551 if (addr) 552 return addr; 553 554 out: 555 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 556 } 557 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 558 559 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 560 struct page *page, gfp_t gfp) 561 { 562 struct vm_area_struct *vma = vmf->vma; 563 struct mem_cgroup *memcg; 564 pgtable_t pgtable; 565 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 566 vm_fault_t ret = 0; 567 568 VM_BUG_ON_PAGE(!PageCompound(page), page); 569 570 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) { 571 put_page(page); 572 count_vm_event(THP_FAULT_FALLBACK); 573 return VM_FAULT_FALLBACK; 574 } 575 576 pgtable = pte_alloc_one(vma->vm_mm); 577 if (unlikely(!pgtable)) { 578 ret = VM_FAULT_OOM; 579 goto release; 580 } 581 582 clear_huge_page(page, vmf->address, HPAGE_PMD_NR); 583 /* 584 * The memory barrier inside __SetPageUptodate makes sure that 585 * clear_huge_page writes become visible before the set_pmd_at() 586 * write. 587 */ 588 __SetPageUptodate(page); 589 590 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 591 if (unlikely(!pmd_none(*vmf->pmd))) { 592 goto unlock_release; 593 } else { 594 pmd_t entry; 595 596 ret = check_stable_address_space(vma->vm_mm); 597 if (ret) 598 goto unlock_release; 599 600 /* Deliver the page fault to userland */ 601 if (userfaultfd_missing(vma)) { 602 vm_fault_t ret2; 603 604 spin_unlock(vmf->ptl); 605 mem_cgroup_cancel_charge(page, memcg, true); 606 put_page(page); 607 pte_free(vma->vm_mm, pgtable); 608 ret2 = handle_userfault(vmf, VM_UFFD_MISSING); 609 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK); 610 return ret2; 611 } 612 613 entry = mk_huge_pmd(page, vma->vm_page_prot); 614 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 615 page_add_new_anon_rmap(page, vma, haddr, true); 616 mem_cgroup_commit_charge(page, memcg, false, true); 617 lru_cache_add_active_or_unevictable(page, vma); 618 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 619 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 620 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 621 mm_inc_nr_ptes(vma->vm_mm); 622 spin_unlock(vmf->ptl); 623 count_vm_event(THP_FAULT_ALLOC); 624 count_memcg_events(memcg, THP_FAULT_ALLOC, 1); 625 } 626 627 return 0; 628 unlock_release: 629 spin_unlock(vmf->ptl); 630 release: 631 if (pgtable) 632 pte_free(vma->vm_mm, pgtable); 633 mem_cgroup_cancel_charge(page, memcg, true); 634 put_page(page); 635 return ret; 636 637 } 638 639 /* 640 * always: directly stall for all thp allocations 641 * defer: wake kswapd and fail if not immediately available 642 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 643 * fail if not immediately available 644 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 645 * available 646 * never: never stall for any thp allocation 647 */ 648 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma, unsigned long addr) 649 { 650 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE); 651 gfp_t this_node = 0; 652 653 #ifdef CONFIG_NUMA 654 struct mempolicy *pol; 655 /* 656 * __GFP_THISNODE is used only when __GFP_DIRECT_RECLAIM is not 657 * specified, to express a general desire to stay on the current 658 * node for optimistic allocation attempts. If the defrag mode 659 * and/or madvise hint requires the direct reclaim then we prefer 660 * to fallback to other node rather than node reclaim because that 661 * can lead to excessive reclaim even though there is free memory 662 * on other nodes. We expect that NUMA preferences are specified 663 * by memory policies. 664 */ 665 pol = get_vma_policy(vma, addr); 666 if (pol->mode != MPOL_BIND) 667 this_node = __GFP_THISNODE; 668 mpol_cond_put(pol); 669 #endif 670 671 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 672 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 673 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 674 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM | this_node; 675 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 676 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM : 677 __GFP_KSWAPD_RECLAIM | this_node); 678 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 679 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM : 680 this_node); 681 return GFP_TRANSHUGE_LIGHT | this_node; 682 } 683 684 /* Caller must hold page table lock. */ 685 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, 686 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 687 struct page *zero_page) 688 { 689 pmd_t entry; 690 if (!pmd_none(*pmd)) 691 return false; 692 entry = mk_pmd(zero_page, vma->vm_page_prot); 693 entry = pmd_mkhuge(entry); 694 if (pgtable) 695 pgtable_trans_huge_deposit(mm, pmd, pgtable); 696 set_pmd_at(mm, haddr, pmd, entry); 697 mm_inc_nr_ptes(mm); 698 return true; 699 } 700 701 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 702 { 703 struct vm_area_struct *vma = vmf->vma; 704 gfp_t gfp; 705 struct page *page; 706 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 707 708 if (!transhuge_vma_suitable(vma, haddr)) 709 return VM_FAULT_FALLBACK; 710 if (unlikely(anon_vma_prepare(vma))) 711 return VM_FAULT_OOM; 712 if (unlikely(khugepaged_enter(vma, vma->vm_flags))) 713 return VM_FAULT_OOM; 714 if (!(vmf->flags & FAULT_FLAG_WRITE) && 715 !mm_forbids_zeropage(vma->vm_mm) && 716 transparent_hugepage_use_zero_page()) { 717 pgtable_t pgtable; 718 struct page *zero_page; 719 bool set; 720 vm_fault_t ret; 721 pgtable = pte_alloc_one(vma->vm_mm); 722 if (unlikely(!pgtable)) 723 return VM_FAULT_OOM; 724 zero_page = mm_get_huge_zero_page(vma->vm_mm); 725 if (unlikely(!zero_page)) { 726 pte_free(vma->vm_mm, pgtable); 727 count_vm_event(THP_FAULT_FALLBACK); 728 return VM_FAULT_FALLBACK; 729 } 730 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 731 ret = 0; 732 set = false; 733 if (pmd_none(*vmf->pmd)) { 734 ret = check_stable_address_space(vma->vm_mm); 735 if (ret) { 736 spin_unlock(vmf->ptl); 737 } else if (userfaultfd_missing(vma)) { 738 spin_unlock(vmf->ptl); 739 ret = handle_userfault(vmf, VM_UFFD_MISSING); 740 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 741 } else { 742 set_huge_zero_page(pgtable, vma->vm_mm, vma, 743 haddr, vmf->pmd, zero_page); 744 spin_unlock(vmf->ptl); 745 set = true; 746 } 747 } else 748 spin_unlock(vmf->ptl); 749 if (!set) 750 pte_free(vma->vm_mm, pgtable); 751 return ret; 752 } 753 gfp = alloc_hugepage_direct_gfpmask(vma, haddr); 754 page = alloc_pages_vma(gfp, HPAGE_PMD_ORDER, vma, haddr, numa_node_id()); 755 if (unlikely(!page)) { 756 count_vm_event(THP_FAULT_FALLBACK); 757 return VM_FAULT_FALLBACK; 758 } 759 prep_transhuge_page(page); 760 return __do_huge_pmd_anonymous_page(vmf, page, gfp); 761 } 762 763 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 764 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 765 pgtable_t pgtable) 766 { 767 struct mm_struct *mm = vma->vm_mm; 768 pmd_t entry; 769 spinlock_t *ptl; 770 771 ptl = pmd_lock(mm, pmd); 772 if (!pmd_none(*pmd)) { 773 if (write) { 774 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 775 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 776 goto out_unlock; 777 } 778 entry = pmd_mkyoung(*pmd); 779 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 780 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 781 update_mmu_cache_pmd(vma, addr, pmd); 782 } 783 784 goto out_unlock; 785 } 786 787 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 788 if (pfn_t_devmap(pfn)) 789 entry = pmd_mkdevmap(entry); 790 if (write) { 791 entry = pmd_mkyoung(pmd_mkdirty(entry)); 792 entry = maybe_pmd_mkwrite(entry, vma); 793 } 794 795 if (pgtable) { 796 pgtable_trans_huge_deposit(mm, pmd, pgtable); 797 mm_inc_nr_ptes(mm); 798 pgtable = NULL; 799 } 800 801 set_pmd_at(mm, addr, pmd, entry); 802 update_mmu_cache_pmd(vma, addr, pmd); 803 804 out_unlock: 805 spin_unlock(ptl); 806 if (pgtable) 807 pte_free(mm, pgtable); 808 } 809 810 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) 811 { 812 unsigned long addr = vmf->address & PMD_MASK; 813 struct vm_area_struct *vma = vmf->vma; 814 pgprot_t pgprot = vma->vm_page_prot; 815 pgtable_t pgtable = NULL; 816 817 /* 818 * If we had pmd_special, we could avoid all these restrictions, 819 * but we need to be consistent with PTEs and architectures that 820 * can't support a 'special' bit. 821 */ 822 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 823 !pfn_t_devmap(pfn)); 824 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 825 (VM_PFNMAP|VM_MIXEDMAP)); 826 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 827 828 if (addr < vma->vm_start || addr >= vma->vm_end) 829 return VM_FAULT_SIGBUS; 830 831 if (arch_needs_pgtable_deposit()) { 832 pgtable = pte_alloc_one(vma->vm_mm); 833 if (!pgtable) 834 return VM_FAULT_OOM; 835 } 836 837 track_pfn_insert(vma, &pgprot, pfn); 838 839 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 840 return VM_FAULT_NOPAGE; 841 } 842 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); 843 844 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 845 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 846 { 847 if (likely(vma->vm_flags & VM_WRITE)) 848 pud = pud_mkwrite(pud); 849 return pud; 850 } 851 852 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 853 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) 854 { 855 struct mm_struct *mm = vma->vm_mm; 856 pud_t entry; 857 spinlock_t *ptl; 858 859 ptl = pud_lock(mm, pud); 860 if (!pud_none(*pud)) { 861 if (write) { 862 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 863 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 864 goto out_unlock; 865 } 866 entry = pud_mkyoung(*pud); 867 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 868 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 869 update_mmu_cache_pud(vma, addr, pud); 870 } 871 goto out_unlock; 872 } 873 874 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 875 if (pfn_t_devmap(pfn)) 876 entry = pud_mkdevmap(entry); 877 if (write) { 878 entry = pud_mkyoung(pud_mkdirty(entry)); 879 entry = maybe_pud_mkwrite(entry, vma); 880 } 881 set_pud_at(mm, addr, pud, entry); 882 update_mmu_cache_pud(vma, addr, pud); 883 884 out_unlock: 885 spin_unlock(ptl); 886 } 887 888 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) 889 { 890 unsigned long addr = vmf->address & PUD_MASK; 891 struct vm_area_struct *vma = vmf->vma; 892 pgprot_t pgprot = vma->vm_page_prot; 893 894 /* 895 * If we had pud_special, we could avoid all these restrictions, 896 * but we need to be consistent with PTEs and architectures that 897 * can't support a 'special' bit. 898 */ 899 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 900 !pfn_t_devmap(pfn)); 901 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 902 (VM_PFNMAP|VM_MIXEDMAP)); 903 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 904 905 if (addr < vma->vm_start || addr >= vma->vm_end) 906 return VM_FAULT_SIGBUS; 907 908 track_pfn_insert(vma, &pgprot, pfn); 909 910 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); 911 return VM_FAULT_NOPAGE; 912 } 913 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); 914 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 915 916 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 917 pmd_t *pmd, int flags) 918 { 919 pmd_t _pmd; 920 921 _pmd = pmd_mkyoung(*pmd); 922 if (flags & FOLL_WRITE) 923 _pmd = pmd_mkdirty(_pmd); 924 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 925 pmd, _pmd, flags & FOLL_WRITE)) 926 update_mmu_cache_pmd(vma, addr, pmd); 927 } 928 929 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 930 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 931 { 932 unsigned long pfn = pmd_pfn(*pmd); 933 struct mm_struct *mm = vma->vm_mm; 934 struct page *page; 935 936 assert_spin_locked(pmd_lockptr(mm, pmd)); 937 938 /* 939 * When we COW a devmap PMD entry, we split it into PTEs, so we should 940 * not be in this function with `flags & FOLL_COW` set. 941 */ 942 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); 943 944 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 945 return NULL; 946 947 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 948 /* pass */; 949 else 950 return NULL; 951 952 if (flags & FOLL_TOUCH) 953 touch_pmd(vma, addr, pmd, flags); 954 955 /* 956 * device mapped pages can only be returned if the 957 * caller will manage the page reference count. 958 */ 959 if (!(flags & FOLL_GET)) 960 return ERR_PTR(-EEXIST); 961 962 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 963 *pgmap = get_dev_pagemap(pfn, *pgmap); 964 if (!*pgmap) 965 return ERR_PTR(-EFAULT); 966 page = pfn_to_page(pfn); 967 get_page(page); 968 969 return page; 970 } 971 972 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 973 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 974 struct vm_area_struct *vma) 975 { 976 spinlock_t *dst_ptl, *src_ptl; 977 struct page *src_page; 978 pmd_t pmd; 979 pgtable_t pgtable = NULL; 980 int ret = -ENOMEM; 981 982 /* Skip if can be re-fill on fault */ 983 if (!vma_is_anonymous(vma)) 984 return 0; 985 986 pgtable = pte_alloc_one(dst_mm); 987 if (unlikely(!pgtable)) 988 goto out; 989 990 dst_ptl = pmd_lock(dst_mm, dst_pmd); 991 src_ptl = pmd_lockptr(src_mm, src_pmd); 992 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 993 994 ret = -EAGAIN; 995 pmd = *src_pmd; 996 997 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 998 if (unlikely(is_swap_pmd(pmd))) { 999 swp_entry_t entry = pmd_to_swp_entry(pmd); 1000 1001 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1002 if (is_write_migration_entry(entry)) { 1003 make_migration_entry_read(&entry); 1004 pmd = swp_entry_to_pmd(entry); 1005 if (pmd_swp_soft_dirty(*src_pmd)) 1006 pmd = pmd_swp_mksoft_dirty(pmd); 1007 set_pmd_at(src_mm, addr, src_pmd, pmd); 1008 } 1009 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1010 mm_inc_nr_ptes(dst_mm); 1011 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1012 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1013 ret = 0; 1014 goto out_unlock; 1015 } 1016 #endif 1017 1018 if (unlikely(!pmd_trans_huge(pmd))) { 1019 pte_free(dst_mm, pgtable); 1020 goto out_unlock; 1021 } 1022 /* 1023 * When page table lock is held, the huge zero pmd should not be 1024 * under splitting since we don't split the page itself, only pmd to 1025 * a page table. 1026 */ 1027 if (is_huge_zero_pmd(pmd)) { 1028 struct page *zero_page; 1029 /* 1030 * get_huge_zero_page() will never allocate a new page here, 1031 * since we already have a zero page to copy. It just takes a 1032 * reference. 1033 */ 1034 zero_page = mm_get_huge_zero_page(dst_mm); 1035 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, 1036 zero_page); 1037 ret = 0; 1038 goto out_unlock; 1039 } 1040 1041 src_page = pmd_page(pmd); 1042 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1043 get_page(src_page); 1044 page_dup_rmap(src_page, true); 1045 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1046 mm_inc_nr_ptes(dst_mm); 1047 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1048 1049 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1050 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1051 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1052 1053 ret = 0; 1054 out_unlock: 1055 spin_unlock(src_ptl); 1056 spin_unlock(dst_ptl); 1057 out: 1058 return ret; 1059 } 1060 1061 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1062 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1063 pud_t *pud, int flags) 1064 { 1065 pud_t _pud; 1066 1067 _pud = pud_mkyoung(*pud); 1068 if (flags & FOLL_WRITE) 1069 _pud = pud_mkdirty(_pud); 1070 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1071 pud, _pud, flags & FOLL_WRITE)) 1072 update_mmu_cache_pud(vma, addr, pud); 1073 } 1074 1075 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1076 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1077 { 1078 unsigned long pfn = pud_pfn(*pud); 1079 struct mm_struct *mm = vma->vm_mm; 1080 struct page *page; 1081 1082 assert_spin_locked(pud_lockptr(mm, pud)); 1083 1084 if (flags & FOLL_WRITE && !pud_write(*pud)) 1085 return NULL; 1086 1087 if (pud_present(*pud) && pud_devmap(*pud)) 1088 /* pass */; 1089 else 1090 return NULL; 1091 1092 if (flags & FOLL_TOUCH) 1093 touch_pud(vma, addr, pud, flags); 1094 1095 /* 1096 * device mapped pages can only be returned if the 1097 * caller will manage the page reference count. 1098 */ 1099 if (!(flags & FOLL_GET)) 1100 return ERR_PTR(-EEXIST); 1101 1102 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1103 *pgmap = get_dev_pagemap(pfn, *pgmap); 1104 if (!*pgmap) 1105 return ERR_PTR(-EFAULT); 1106 page = pfn_to_page(pfn); 1107 get_page(page); 1108 1109 return page; 1110 } 1111 1112 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1113 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1114 struct vm_area_struct *vma) 1115 { 1116 spinlock_t *dst_ptl, *src_ptl; 1117 pud_t pud; 1118 int ret; 1119 1120 dst_ptl = pud_lock(dst_mm, dst_pud); 1121 src_ptl = pud_lockptr(src_mm, src_pud); 1122 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1123 1124 ret = -EAGAIN; 1125 pud = *src_pud; 1126 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1127 goto out_unlock; 1128 1129 /* 1130 * When page table lock is held, the huge zero pud should not be 1131 * under splitting since we don't split the page itself, only pud to 1132 * a page table. 1133 */ 1134 if (is_huge_zero_pud(pud)) { 1135 /* No huge zero pud yet */ 1136 } 1137 1138 pudp_set_wrprotect(src_mm, addr, src_pud); 1139 pud = pud_mkold(pud_wrprotect(pud)); 1140 set_pud_at(dst_mm, addr, dst_pud, pud); 1141 1142 ret = 0; 1143 out_unlock: 1144 spin_unlock(src_ptl); 1145 spin_unlock(dst_ptl); 1146 return ret; 1147 } 1148 1149 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1150 { 1151 pud_t entry; 1152 unsigned long haddr; 1153 bool write = vmf->flags & FAULT_FLAG_WRITE; 1154 1155 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1156 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1157 goto unlock; 1158 1159 entry = pud_mkyoung(orig_pud); 1160 if (write) 1161 entry = pud_mkdirty(entry); 1162 haddr = vmf->address & HPAGE_PUD_MASK; 1163 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) 1164 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); 1165 1166 unlock: 1167 spin_unlock(vmf->ptl); 1168 } 1169 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1170 1171 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd) 1172 { 1173 pmd_t entry; 1174 unsigned long haddr; 1175 bool write = vmf->flags & FAULT_FLAG_WRITE; 1176 1177 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1178 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1179 goto unlock; 1180 1181 entry = pmd_mkyoung(orig_pmd); 1182 if (write) 1183 entry = pmd_mkdirty(entry); 1184 haddr = vmf->address & HPAGE_PMD_MASK; 1185 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) 1186 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); 1187 1188 unlock: 1189 spin_unlock(vmf->ptl); 1190 } 1191 1192 static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, 1193 pmd_t orig_pmd, struct page *page) 1194 { 1195 struct vm_area_struct *vma = vmf->vma; 1196 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1197 struct mem_cgroup *memcg; 1198 pgtable_t pgtable; 1199 pmd_t _pmd; 1200 int i; 1201 vm_fault_t ret = 0; 1202 struct page **pages; 1203 struct mmu_notifier_range range; 1204 1205 pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *), 1206 GFP_KERNEL); 1207 if (unlikely(!pages)) { 1208 ret |= VM_FAULT_OOM; 1209 goto out; 1210 } 1211 1212 for (i = 0; i < HPAGE_PMD_NR; i++) { 1213 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma, 1214 vmf->address, page_to_nid(page)); 1215 if (unlikely(!pages[i] || 1216 mem_cgroup_try_charge_delay(pages[i], vma->vm_mm, 1217 GFP_KERNEL, &memcg, false))) { 1218 if (pages[i]) 1219 put_page(pages[i]); 1220 while (--i >= 0) { 1221 memcg = (void *)page_private(pages[i]); 1222 set_page_private(pages[i], 0); 1223 mem_cgroup_cancel_charge(pages[i], memcg, 1224 false); 1225 put_page(pages[i]); 1226 } 1227 kfree(pages); 1228 ret |= VM_FAULT_OOM; 1229 goto out; 1230 } 1231 set_page_private(pages[i], (unsigned long)memcg); 1232 } 1233 1234 for (i = 0; i < HPAGE_PMD_NR; i++) { 1235 copy_user_highpage(pages[i], page + i, 1236 haddr + PAGE_SIZE * i, vma); 1237 __SetPageUptodate(pages[i]); 1238 cond_resched(); 1239 } 1240 1241 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1242 haddr, haddr + HPAGE_PMD_SIZE); 1243 mmu_notifier_invalidate_range_start(&range); 1244 1245 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1246 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1247 goto out_free_pages; 1248 VM_BUG_ON_PAGE(!PageHead(page), page); 1249 1250 /* 1251 * Leave pmd empty until pte is filled note we must notify here as 1252 * concurrent CPU thread might write to new page before the call to 1253 * mmu_notifier_invalidate_range_end() happens which can lead to a 1254 * device seeing memory write in different order than CPU. 1255 * 1256 * See Documentation/vm/mmu_notifier.rst 1257 */ 1258 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); 1259 1260 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd); 1261 pmd_populate(vma->vm_mm, &_pmd, pgtable); 1262 1263 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 1264 pte_t entry; 1265 entry = mk_pte(pages[i], vma->vm_page_prot); 1266 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1267 memcg = (void *)page_private(pages[i]); 1268 set_page_private(pages[i], 0); 1269 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false); 1270 mem_cgroup_commit_charge(pages[i], memcg, false, false); 1271 lru_cache_add_active_or_unevictable(pages[i], vma); 1272 vmf->pte = pte_offset_map(&_pmd, haddr); 1273 VM_BUG_ON(!pte_none(*vmf->pte)); 1274 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry); 1275 pte_unmap(vmf->pte); 1276 } 1277 kfree(pages); 1278 1279 smp_wmb(); /* make pte visible before pmd */ 1280 pmd_populate(vma->vm_mm, vmf->pmd, pgtable); 1281 page_remove_rmap(page, true); 1282 spin_unlock(vmf->ptl); 1283 1284 /* 1285 * No need to double call mmu_notifier->invalidate_range() callback as 1286 * the above pmdp_huge_clear_flush_notify() did already call it. 1287 */ 1288 mmu_notifier_invalidate_range_only_end(&range); 1289 1290 ret |= VM_FAULT_WRITE; 1291 put_page(page); 1292 1293 out: 1294 return ret; 1295 1296 out_free_pages: 1297 spin_unlock(vmf->ptl); 1298 mmu_notifier_invalidate_range_end(&range); 1299 for (i = 0; i < HPAGE_PMD_NR; i++) { 1300 memcg = (void *)page_private(pages[i]); 1301 set_page_private(pages[i], 0); 1302 mem_cgroup_cancel_charge(pages[i], memcg, false); 1303 put_page(pages[i]); 1304 } 1305 kfree(pages); 1306 goto out; 1307 } 1308 1309 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) 1310 { 1311 struct vm_area_struct *vma = vmf->vma; 1312 struct page *page = NULL, *new_page; 1313 struct mem_cgroup *memcg; 1314 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1315 struct mmu_notifier_range range; 1316 gfp_t huge_gfp; /* for allocation and charge */ 1317 vm_fault_t ret = 0; 1318 1319 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1320 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1321 if (is_huge_zero_pmd(orig_pmd)) 1322 goto alloc; 1323 spin_lock(vmf->ptl); 1324 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1325 goto out_unlock; 1326 1327 page = pmd_page(orig_pmd); 1328 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); 1329 /* 1330 * We can only reuse the page if nobody else maps the huge page or it's 1331 * part. 1332 */ 1333 if (!trylock_page(page)) { 1334 get_page(page); 1335 spin_unlock(vmf->ptl); 1336 lock_page(page); 1337 spin_lock(vmf->ptl); 1338 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1339 unlock_page(page); 1340 put_page(page); 1341 goto out_unlock; 1342 } 1343 put_page(page); 1344 } 1345 if (reuse_swap_page(page, NULL)) { 1346 pmd_t entry; 1347 entry = pmd_mkyoung(orig_pmd); 1348 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1349 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1350 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1351 ret |= VM_FAULT_WRITE; 1352 unlock_page(page); 1353 goto out_unlock; 1354 } 1355 unlock_page(page); 1356 get_page(page); 1357 spin_unlock(vmf->ptl); 1358 alloc: 1359 if (__transparent_hugepage_enabled(vma) && 1360 !transparent_hugepage_debug_cow()) { 1361 huge_gfp = alloc_hugepage_direct_gfpmask(vma, haddr); 1362 new_page = alloc_pages_vma(huge_gfp, HPAGE_PMD_ORDER, vma, 1363 haddr, numa_node_id()); 1364 } else 1365 new_page = NULL; 1366 1367 if (likely(new_page)) { 1368 prep_transhuge_page(new_page); 1369 } else { 1370 if (!page) { 1371 split_huge_pmd(vma, vmf->pmd, vmf->address); 1372 ret |= VM_FAULT_FALLBACK; 1373 } else { 1374 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page); 1375 if (ret & VM_FAULT_OOM) { 1376 split_huge_pmd(vma, vmf->pmd, vmf->address); 1377 ret |= VM_FAULT_FALLBACK; 1378 } 1379 put_page(page); 1380 } 1381 count_vm_event(THP_FAULT_FALLBACK); 1382 goto out; 1383 } 1384 1385 if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm, 1386 huge_gfp, &memcg, true))) { 1387 put_page(new_page); 1388 split_huge_pmd(vma, vmf->pmd, vmf->address); 1389 if (page) 1390 put_page(page); 1391 ret |= VM_FAULT_FALLBACK; 1392 count_vm_event(THP_FAULT_FALLBACK); 1393 goto out; 1394 } 1395 1396 count_vm_event(THP_FAULT_ALLOC); 1397 count_memcg_events(memcg, THP_FAULT_ALLOC, 1); 1398 1399 if (!page) 1400 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR); 1401 else 1402 copy_user_huge_page(new_page, page, vmf->address, 1403 vma, HPAGE_PMD_NR); 1404 __SetPageUptodate(new_page); 1405 1406 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1407 haddr, haddr + HPAGE_PMD_SIZE); 1408 mmu_notifier_invalidate_range_start(&range); 1409 1410 spin_lock(vmf->ptl); 1411 if (page) 1412 put_page(page); 1413 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1414 spin_unlock(vmf->ptl); 1415 mem_cgroup_cancel_charge(new_page, memcg, true); 1416 put_page(new_page); 1417 goto out_mn; 1418 } else { 1419 pmd_t entry; 1420 entry = mk_huge_pmd(new_page, vma->vm_page_prot); 1421 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1422 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); 1423 page_add_new_anon_rmap(new_page, vma, haddr, true); 1424 mem_cgroup_commit_charge(new_page, memcg, false, true); 1425 lru_cache_add_active_or_unevictable(new_page, vma); 1426 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 1427 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1428 if (!page) { 1429 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1430 } else { 1431 VM_BUG_ON_PAGE(!PageHead(page), page); 1432 page_remove_rmap(page, true); 1433 put_page(page); 1434 } 1435 ret |= VM_FAULT_WRITE; 1436 } 1437 spin_unlock(vmf->ptl); 1438 out_mn: 1439 /* 1440 * No need to double call mmu_notifier->invalidate_range() callback as 1441 * the above pmdp_huge_clear_flush_notify() did already call it. 1442 */ 1443 mmu_notifier_invalidate_range_only_end(&range); 1444 out: 1445 return ret; 1446 out_unlock: 1447 spin_unlock(vmf->ptl); 1448 return ret; 1449 } 1450 1451 /* 1452 * FOLL_FORCE can write to even unwritable pmd's, but only 1453 * after we've gone through a COW cycle and they are dirty. 1454 */ 1455 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) 1456 { 1457 return pmd_write(pmd) || 1458 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); 1459 } 1460 1461 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1462 unsigned long addr, 1463 pmd_t *pmd, 1464 unsigned int flags) 1465 { 1466 struct mm_struct *mm = vma->vm_mm; 1467 struct page *page = NULL; 1468 1469 assert_spin_locked(pmd_lockptr(mm, pmd)); 1470 1471 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) 1472 goto out; 1473 1474 /* Avoid dumping huge zero page */ 1475 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1476 return ERR_PTR(-EFAULT); 1477 1478 /* Full NUMA hinting faults to serialise migration in fault paths */ 1479 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) 1480 goto out; 1481 1482 page = pmd_page(*pmd); 1483 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1484 if (flags & FOLL_TOUCH) 1485 touch_pmd(vma, addr, pmd, flags); 1486 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { 1487 /* 1488 * We don't mlock() pte-mapped THPs. This way we can avoid 1489 * leaking mlocked pages into non-VM_LOCKED VMAs. 1490 * 1491 * For anon THP: 1492 * 1493 * In most cases the pmd is the only mapping of the page as we 1494 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for 1495 * writable private mappings in populate_vma_page_range(). 1496 * 1497 * The only scenario when we have the page shared here is if we 1498 * mlocking read-only mapping shared over fork(). We skip 1499 * mlocking such pages. 1500 * 1501 * For file THP: 1502 * 1503 * We can expect PageDoubleMap() to be stable under page lock: 1504 * for file pages we set it in page_add_file_rmap(), which 1505 * requires page to be locked. 1506 */ 1507 1508 if (PageAnon(page) && compound_mapcount(page) != 1) 1509 goto skip_mlock; 1510 if (PageDoubleMap(page) || !page->mapping) 1511 goto skip_mlock; 1512 if (!trylock_page(page)) 1513 goto skip_mlock; 1514 lru_add_drain(); 1515 if (page->mapping && !PageDoubleMap(page)) 1516 mlock_vma_page(page); 1517 unlock_page(page); 1518 } 1519 skip_mlock: 1520 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1521 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1522 if (flags & FOLL_GET) 1523 get_page(page); 1524 1525 out: 1526 return page; 1527 } 1528 1529 /* NUMA hinting page fault entry point for trans huge pmds */ 1530 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) 1531 { 1532 struct vm_area_struct *vma = vmf->vma; 1533 struct anon_vma *anon_vma = NULL; 1534 struct page *page; 1535 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1536 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id(); 1537 int target_nid, last_cpupid = -1; 1538 bool page_locked; 1539 bool migrated = false; 1540 bool was_writable; 1541 int flags = 0; 1542 1543 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1544 if (unlikely(!pmd_same(pmd, *vmf->pmd))) 1545 goto out_unlock; 1546 1547 /* 1548 * If there are potential migrations, wait for completion and retry 1549 * without disrupting NUMA hinting information. Do not relock and 1550 * check_same as the page may no longer be mapped. 1551 */ 1552 if (unlikely(pmd_trans_migrating(*vmf->pmd))) { 1553 page = pmd_page(*vmf->pmd); 1554 if (!get_page_unless_zero(page)) 1555 goto out_unlock; 1556 spin_unlock(vmf->ptl); 1557 put_and_wait_on_page_locked(page); 1558 goto out; 1559 } 1560 1561 page = pmd_page(pmd); 1562 BUG_ON(is_huge_zero_page(page)); 1563 page_nid = page_to_nid(page); 1564 last_cpupid = page_cpupid_last(page); 1565 count_vm_numa_event(NUMA_HINT_FAULTS); 1566 if (page_nid == this_nid) { 1567 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 1568 flags |= TNF_FAULT_LOCAL; 1569 } 1570 1571 /* See similar comment in do_numa_page for explanation */ 1572 if (!pmd_savedwrite(pmd)) 1573 flags |= TNF_NO_GROUP; 1574 1575 /* 1576 * Acquire the page lock to serialise THP migrations but avoid dropping 1577 * page_table_lock if at all possible 1578 */ 1579 page_locked = trylock_page(page); 1580 target_nid = mpol_misplaced(page, vma, haddr); 1581 if (target_nid == NUMA_NO_NODE) { 1582 /* If the page was locked, there are no parallel migrations */ 1583 if (page_locked) 1584 goto clear_pmdnuma; 1585 } 1586 1587 /* Migration could have started since the pmd_trans_migrating check */ 1588 if (!page_locked) { 1589 page_nid = NUMA_NO_NODE; 1590 if (!get_page_unless_zero(page)) 1591 goto out_unlock; 1592 spin_unlock(vmf->ptl); 1593 put_and_wait_on_page_locked(page); 1594 goto out; 1595 } 1596 1597 /* 1598 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma 1599 * to serialises splits 1600 */ 1601 get_page(page); 1602 spin_unlock(vmf->ptl); 1603 anon_vma = page_lock_anon_vma_read(page); 1604 1605 /* Confirm the PMD did not change while page_table_lock was released */ 1606 spin_lock(vmf->ptl); 1607 if (unlikely(!pmd_same(pmd, *vmf->pmd))) { 1608 unlock_page(page); 1609 put_page(page); 1610 page_nid = NUMA_NO_NODE; 1611 goto out_unlock; 1612 } 1613 1614 /* Bail if we fail to protect against THP splits for any reason */ 1615 if (unlikely(!anon_vma)) { 1616 put_page(page); 1617 page_nid = NUMA_NO_NODE; 1618 goto clear_pmdnuma; 1619 } 1620 1621 /* 1622 * Since we took the NUMA fault, we must have observed the !accessible 1623 * bit. Make sure all other CPUs agree with that, to avoid them 1624 * modifying the page we're about to migrate. 1625 * 1626 * Must be done under PTL such that we'll observe the relevant 1627 * inc_tlb_flush_pending(). 1628 * 1629 * We are not sure a pending tlb flush here is for a huge page 1630 * mapping or not. Hence use the tlb range variant 1631 */ 1632 if (mm_tlb_flush_pending(vma->vm_mm)) { 1633 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE); 1634 /* 1635 * change_huge_pmd() released the pmd lock before 1636 * invalidating the secondary MMUs sharing the primary 1637 * MMU pagetables (with ->invalidate_range()). The 1638 * mmu_notifier_invalidate_range_end() (which 1639 * internally calls ->invalidate_range()) in 1640 * change_pmd_range() will run after us, so we can't 1641 * rely on it here and we need an explicit invalidate. 1642 */ 1643 mmu_notifier_invalidate_range(vma->vm_mm, haddr, 1644 haddr + HPAGE_PMD_SIZE); 1645 } 1646 1647 /* 1648 * Migrate the THP to the requested node, returns with page unlocked 1649 * and access rights restored. 1650 */ 1651 spin_unlock(vmf->ptl); 1652 1653 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma, 1654 vmf->pmd, pmd, vmf->address, page, target_nid); 1655 if (migrated) { 1656 flags |= TNF_MIGRATED; 1657 page_nid = target_nid; 1658 } else 1659 flags |= TNF_MIGRATE_FAIL; 1660 1661 goto out; 1662 clear_pmdnuma: 1663 BUG_ON(!PageLocked(page)); 1664 was_writable = pmd_savedwrite(pmd); 1665 pmd = pmd_modify(pmd, vma->vm_page_prot); 1666 pmd = pmd_mkyoung(pmd); 1667 if (was_writable) 1668 pmd = pmd_mkwrite(pmd); 1669 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1670 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1671 unlock_page(page); 1672 out_unlock: 1673 spin_unlock(vmf->ptl); 1674 1675 out: 1676 if (anon_vma) 1677 page_unlock_anon_vma_read(anon_vma); 1678 1679 if (page_nid != NUMA_NO_NODE) 1680 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1681 flags); 1682 1683 return 0; 1684 } 1685 1686 /* 1687 * Return true if we do MADV_FREE successfully on entire pmd page. 1688 * Otherwise, return false. 1689 */ 1690 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1691 pmd_t *pmd, unsigned long addr, unsigned long next) 1692 { 1693 spinlock_t *ptl; 1694 pmd_t orig_pmd; 1695 struct page *page; 1696 struct mm_struct *mm = tlb->mm; 1697 bool ret = false; 1698 1699 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1700 1701 ptl = pmd_trans_huge_lock(pmd, vma); 1702 if (!ptl) 1703 goto out_unlocked; 1704 1705 orig_pmd = *pmd; 1706 if (is_huge_zero_pmd(orig_pmd)) 1707 goto out; 1708 1709 if (unlikely(!pmd_present(orig_pmd))) { 1710 VM_BUG_ON(thp_migration_supported() && 1711 !is_pmd_migration_entry(orig_pmd)); 1712 goto out; 1713 } 1714 1715 page = pmd_page(orig_pmd); 1716 /* 1717 * If other processes are mapping this page, we couldn't discard 1718 * the page unless they all do MADV_FREE so let's skip the page. 1719 */ 1720 if (page_mapcount(page) != 1) 1721 goto out; 1722 1723 if (!trylock_page(page)) 1724 goto out; 1725 1726 /* 1727 * If user want to discard part-pages of THP, split it so MADV_FREE 1728 * will deactivate only them. 1729 */ 1730 if (next - addr != HPAGE_PMD_SIZE) { 1731 get_page(page); 1732 spin_unlock(ptl); 1733 split_huge_page(page); 1734 unlock_page(page); 1735 put_page(page); 1736 goto out_unlocked; 1737 } 1738 1739 if (PageDirty(page)) 1740 ClearPageDirty(page); 1741 unlock_page(page); 1742 1743 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1744 pmdp_invalidate(vma, addr, pmd); 1745 orig_pmd = pmd_mkold(orig_pmd); 1746 orig_pmd = pmd_mkclean(orig_pmd); 1747 1748 set_pmd_at(mm, addr, pmd, orig_pmd); 1749 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1750 } 1751 1752 mark_page_lazyfree(page); 1753 ret = true; 1754 out: 1755 spin_unlock(ptl); 1756 out_unlocked: 1757 return ret; 1758 } 1759 1760 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1761 { 1762 pgtable_t pgtable; 1763 1764 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1765 pte_free(mm, pgtable); 1766 mm_dec_nr_ptes(mm); 1767 } 1768 1769 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1770 pmd_t *pmd, unsigned long addr) 1771 { 1772 pmd_t orig_pmd; 1773 spinlock_t *ptl; 1774 1775 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1776 1777 ptl = __pmd_trans_huge_lock(pmd, vma); 1778 if (!ptl) 1779 return 0; 1780 /* 1781 * For architectures like ppc64 we look at deposited pgtable 1782 * when calling pmdp_huge_get_and_clear. So do the 1783 * pgtable_trans_huge_withdraw after finishing pmdp related 1784 * operations. 1785 */ 1786 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, 1787 tlb->fullmm); 1788 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1789 if (vma_is_dax(vma)) { 1790 if (arch_needs_pgtable_deposit()) 1791 zap_deposited_table(tlb->mm, pmd); 1792 spin_unlock(ptl); 1793 if (is_huge_zero_pmd(orig_pmd)) 1794 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1795 } else if (is_huge_zero_pmd(orig_pmd)) { 1796 zap_deposited_table(tlb->mm, pmd); 1797 spin_unlock(ptl); 1798 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1799 } else { 1800 struct page *page = NULL; 1801 int flush_needed = 1; 1802 1803 if (pmd_present(orig_pmd)) { 1804 page = pmd_page(orig_pmd); 1805 page_remove_rmap(page, true); 1806 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1807 VM_BUG_ON_PAGE(!PageHead(page), page); 1808 } else if (thp_migration_supported()) { 1809 swp_entry_t entry; 1810 1811 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1812 entry = pmd_to_swp_entry(orig_pmd); 1813 page = pfn_to_page(swp_offset(entry)); 1814 flush_needed = 0; 1815 } else 1816 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1817 1818 if (PageAnon(page)) { 1819 zap_deposited_table(tlb->mm, pmd); 1820 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1821 } else { 1822 if (arch_needs_pgtable_deposit()) 1823 zap_deposited_table(tlb->mm, pmd); 1824 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1825 } 1826 1827 spin_unlock(ptl); 1828 if (flush_needed) 1829 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1830 } 1831 return 1; 1832 } 1833 1834 #ifndef pmd_move_must_withdraw 1835 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1836 spinlock_t *old_pmd_ptl, 1837 struct vm_area_struct *vma) 1838 { 1839 /* 1840 * With split pmd lock we also need to move preallocated 1841 * PTE page table if new_pmd is on different PMD page table. 1842 * 1843 * We also don't deposit and withdraw tables for file pages. 1844 */ 1845 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1846 } 1847 #endif 1848 1849 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1850 { 1851 #ifdef CONFIG_MEM_SOFT_DIRTY 1852 if (unlikely(is_pmd_migration_entry(pmd))) 1853 pmd = pmd_swp_mksoft_dirty(pmd); 1854 else if (pmd_present(pmd)) 1855 pmd = pmd_mksoft_dirty(pmd); 1856 #endif 1857 return pmd; 1858 } 1859 1860 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1861 unsigned long new_addr, unsigned long old_end, 1862 pmd_t *old_pmd, pmd_t *new_pmd) 1863 { 1864 spinlock_t *old_ptl, *new_ptl; 1865 pmd_t pmd; 1866 struct mm_struct *mm = vma->vm_mm; 1867 bool force_flush = false; 1868 1869 if ((old_addr & ~HPAGE_PMD_MASK) || 1870 (new_addr & ~HPAGE_PMD_MASK) || 1871 old_end - old_addr < HPAGE_PMD_SIZE) 1872 return false; 1873 1874 /* 1875 * The destination pmd shouldn't be established, free_pgtables() 1876 * should have release it. 1877 */ 1878 if (WARN_ON(!pmd_none(*new_pmd))) { 1879 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1880 return false; 1881 } 1882 1883 /* 1884 * We don't have to worry about the ordering of src and dst 1885 * ptlocks because exclusive mmap_sem prevents deadlock. 1886 */ 1887 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1888 if (old_ptl) { 1889 new_ptl = pmd_lockptr(mm, new_pmd); 1890 if (new_ptl != old_ptl) 1891 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1892 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1893 if (pmd_present(pmd)) 1894 force_flush = true; 1895 VM_BUG_ON(!pmd_none(*new_pmd)); 1896 1897 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1898 pgtable_t pgtable; 1899 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1900 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1901 } 1902 pmd = move_soft_dirty_pmd(pmd); 1903 set_pmd_at(mm, new_addr, new_pmd, pmd); 1904 if (force_flush) 1905 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1906 if (new_ptl != old_ptl) 1907 spin_unlock(new_ptl); 1908 spin_unlock(old_ptl); 1909 return true; 1910 } 1911 return false; 1912 } 1913 1914 /* 1915 * Returns 1916 * - 0 if PMD could not be locked 1917 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary 1918 * - HPAGE_PMD_NR is protections changed and TLB flush necessary 1919 */ 1920 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 1921 unsigned long addr, pgprot_t newprot, int prot_numa) 1922 { 1923 struct mm_struct *mm = vma->vm_mm; 1924 spinlock_t *ptl; 1925 pmd_t entry; 1926 bool preserve_write; 1927 int ret; 1928 1929 ptl = __pmd_trans_huge_lock(pmd, vma); 1930 if (!ptl) 1931 return 0; 1932 1933 preserve_write = prot_numa && pmd_write(*pmd); 1934 ret = 1; 1935 1936 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1937 if (is_swap_pmd(*pmd)) { 1938 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1939 1940 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1941 if (is_write_migration_entry(entry)) { 1942 pmd_t newpmd; 1943 /* 1944 * A protection check is difficult so 1945 * just be safe and disable write 1946 */ 1947 make_migration_entry_read(&entry); 1948 newpmd = swp_entry_to_pmd(entry); 1949 if (pmd_swp_soft_dirty(*pmd)) 1950 newpmd = pmd_swp_mksoft_dirty(newpmd); 1951 set_pmd_at(mm, addr, pmd, newpmd); 1952 } 1953 goto unlock; 1954 } 1955 #endif 1956 1957 /* 1958 * Avoid trapping faults against the zero page. The read-only 1959 * data is likely to be read-cached on the local CPU and 1960 * local/remote hits to the zero page are not interesting. 1961 */ 1962 if (prot_numa && is_huge_zero_pmd(*pmd)) 1963 goto unlock; 1964 1965 if (prot_numa && pmd_protnone(*pmd)) 1966 goto unlock; 1967 1968 /* 1969 * In case prot_numa, we are under down_read(mmap_sem). It's critical 1970 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1971 * which is also under down_read(mmap_sem): 1972 * 1973 * CPU0: CPU1: 1974 * change_huge_pmd(prot_numa=1) 1975 * pmdp_huge_get_and_clear_notify() 1976 * madvise_dontneed() 1977 * zap_pmd_range() 1978 * pmd_trans_huge(*pmd) == 0 (without ptl) 1979 * // skip the pmd 1980 * set_pmd_at(); 1981 * // pmd is re-established 1982 * 1983 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 1984 * which may break userspace. 1985 * 1986 * pmdp_invalidate() is required to make sure we don't miss 1987 * dirty/young flags set by hardware. 1988 */ 1989 entry = pmdp_invalidate(vma, addr, pmd); 1990 1991 entry = pmd_modify(entry, newprot); 1992 if (preserve_write) 1993 entry = pmd_mk_savedwrite(entry); 1994 ret = HPAGE_PMD_NR; 1995 set_pmd_at(mm, addr, pmd, entry); 1996 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); 1997 unlock: 1998 spin_unlock(ptl); 1999 return ret; 2000 } 2001 2002 /* 2003 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 2004 * 2005 * Note that if it returns page table lock pointer, this routine returns without 2006 * unlocking page table lock. So callers must unlock it. 2007 */ 2008 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 2009 { 2010 spinlock_t *ptl; 2011 ptl = pmd_lock(vma->vm_mm, pmd); 2012 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 2013 pmd_devmap(*pmd))) 2014 return ptl; 2015 spin_unlock(ptl); 2016 return NULL; 2017 } 2018 2019 /* 2020 * Returns true if a given pud maps a thp, false otherwise. 2021 * 2022 * Note that if it returns true, this routine returns without unlocking page 2023 * table lock. So callers must unlock it. 2024 */ 2025 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 2026 { 2027 spinlock_t *ptl; 2028 2029 ptl = pud_lock(vma->vm_mm, pud); 2030 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 2031 return ptl; 2032 spin_unlock(ptl); 2033 return NULL; 2034 } 2035 2036 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 2037 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 2038 pud_t *pud, unsigned long addr) 2039 { 2040 spinlock_t *ptl; 2041 2042 ptl = __pud_trans_huge_lock(pud, vma); 2043 if (!ptl) 2044 return 0; 2045 /* 2046 * For architectures like ppc64 we look at deposited pgtable 2047 * when calling pudp_huge_get_and_clear. So do the 2048 * pgtable_trans_huge_withdraw after finishing pudp related 2049 * operations. 2050 */ 2051 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 2052 tlb_remove_pud_tlb_entry(tlb, pud, addr); 2053 if (vma_is_dax(vma)) { 2054 spin_unlock(ptl); 2055 /* No zero page support yet */ 2056 } else { 2057 /* No support for anonymous PUD pages yet */ 2058 BUG(); 2059 } 2060 return 1; 2061 } 2062 2063 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 2064 unsigned long haddr) 2065 { 2066 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 2067 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2068 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 2069 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 2070 2071 count_vm_event(THP_SPLIT_PUD); 2072 2073 pudp_huge_clear_flush_notify(vma, haddr, pud); 2074 } 2075 2076 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 2077 unsigned long address) 2078 { 2079 spinlock_t *ptl; 2080 struct mmu_notifier_range range; 2081 2082 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2083 address & HPAGE_PUD_MASK, 2084 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 2085 mmu_notifier_invalidate_range_start(&range); 2086 ptl = pud_lock(vma->vm_mm, pud); 2087 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 2088 goto out; 2089 __split_huge_pud_locked(vma, pud, range.start); 2090 2091 out: 2092 spin_unlock(ptl); 2093 /* 2094 * No need to double call mmu_notifier->invalidate_range() callback as 2095 * the above pudp_huge_clear_flush_notify() did already call it. 2096 */ 2097 mmu_notifier_invalidate_range_only_end(&range); 2098 } 2099 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 2100 2101 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2102 unsigned long haddr, pmd_t *pmd) 2103 { 2104 struct mm_struct *mm = vma->vm_mm; 2105 pgtable_t pgtable; 2106 pmd_t _pmd; 2107 int i; 2108 2109 /* 2110 * Leave pmd empty until pte is filled note that it is fine to delay 2111 * notification until mmu_notifier_invalidate_range_end() as we are 2112 * replacing a zero pmd write protected page with a zero pte write 2113 * protected page. 2114 * 2115 * See Documentation/vm/mmu_notifier.rst 2116 */ 2117 pmdp_huge_clear_flush(vma, haddr, pmd); 2118 2119 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2120 pmd_populate(mm, &_pmd, pgtable); 2121 2122 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 2123 pte_t *pte, entry; 2124 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 2125 entry = pte_mkspecial(entry); 2126 pte = pte_offset_map(&_pmd, haddr); 2127 VM_BUG_ON(!pte_none(*pte)); 2128 set_pte_at(mm, haddr, pte, entry); 2129 pte_unmap(pte); 2130 } 2131 smp_wmb(); /* make pte visible before pmd */ 2132 pmd_populate(mm, pmd, pgtable); 2133 } 2134 2135 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2136 unsigned long haddr, bool freeze) 2137 { 2138 struct mm_struct *mm = vma->vm_mm; 2139 struct page *page; 2140 pgtable_t pgtable; 2141 pmd_t old_pmd, _pmd; 2142 bool young, write, soft_dirty, pmd_migration = false; 2143 unsigned long addr; 2144 int i; 2145 2146 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2147 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2148 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2149 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2150 && !pmd_devmap(*pmd)); 2151 2152 count_vm_event(THP_SPLIT_PMD); 2153 2154 if (!vma_is_anonymous(vma)) { 2155 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 2156 /* 2157 * We are going to unmap this huge page. So 2158 * just go ahead and zap it 2159 */ 2160 if (arch_needs_pgtable_deposit()) 2161 zap_deposited_table(mm, pmd); 2162 if (vma_is_dax(vma)) 2163 return; 2164 page = pmd_page(_pmd); 2165 if (!PageDirty(page) && pmd_dirty(_pmd)) 2166 set_page_dirty(page); 2167 if (!PageReferenced(page) && pmd_young(_pmd)) 2168 SetPageReferenced(page); 2169 page_remove_rmap(page, true); 2170 put_page(page); 2171 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2172 return; 2173 } else if (is_huge_zero_pmd(*pmd)) { 2174 /* 2175 * FIXME: Do we want to invalidate secondary mmu by calling 2176 * mmu_notifier_invalidate_range() see comments below inside 2177 * __split_huge_pmd() ? 2178 * 2179 * We are going from a zero huge page write protected to zero 2180 * small page also write protected so it does not seems useful 2181 * to invalidate secondary mmu at this time. 2182 */ 2183 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2184 } 2185 2186 /* 2187 * Up to this point the pmd is present and huge and userland has the 2188 * whole access to the hugepage during the split (which happens in 2189 * place). If we overwrite the pmd with the not-huge version pointing 2190 * to the pte here (which of course we could if all CPUs were bug 2191 * free), userland could trigger a small page size TLB miss on the 2192 * small sized TLB while the hugepage TLB entry is still established in 2193 * the huge TLB. Some CPU doesn't like that. 2194 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum 2195 * 383 on page 93. Intel should be safe but is also warns that it's 2196 * only safe if the permission and cache attributes of the two entries 2197 * loaded in the two TLB is identical (which should be the case here). 2198 * But it is generally safer to never allow small and huge TLB entries 2199 * for the same virtual address to be loaded simultaneously. So instead 2200 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2201 * current pmd notpresent (atomically because here the pmd_trans_huge 2202 * must remain set at all times on the pmd until the split is complete 2203 * for this pmd), then we flush the SMP TLB and finally we write the 2204 * non-huge version of the pmd entry with pmd_populate. 2205 */ 2206 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2207 2208 pmd_migration = is_pmd_migration_entry(old_pmd); 2209 if (unlikely(pmd_migration)) { 2210 swp_entry_t entry; 2211 2212 entry = pmd_to_swp_entry(old_pmd); 2213 page = pfn_to_page(swp_offset(entry)); 2214 write = is_write_migration_entry(entry); 2215 young = false; 2216 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2217 } else { 2218 page = pmd_page(old_pmd); 2219 if (pmd_dirty(old_pmd)) 2220 SetPageDirty(page); 2221 write = pmd_write(old_pmd); 2222 young = pmd_young(old_pmd); 2223 soft_dirty = pmd_soft_dirty(old_pmd); 2224 } 2225 VM_BUG_ON_PAGE(!page_count(page), page); 2226 page_ref_add(page, HPAGE_PMD_NR - 1); 2227 2228 /* 2229 * Withdraw the table only after we mark the pmd entry invalid. 2230 * This's critical for some architectures (Power). 2231 */ 2232 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2233 pmd_populate(mm, &_pmd, pgtable); 2234 2235 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2236 pte_t entry, *pte; 2237 /* 2238 * Note that NUMA hinting access restrictions are not 2239 * transferred to avoid any possibility of altering 2240 * permissions across VMAs. 2241 */ 2242 if (freeze || pmd_migration) { 2243 swp_entry_t swp_entry; 2244 swp_entry = make_migration_entry(page + i, write); 2245 entry = swp_entry_to_pte(swp_entry); 2246 if (soft_dirty) 2247 entry = pte_swp_mksoft_dirty(entry); 2248 } else { 2249 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2250 entry = maybe_mkwrite(entry, vma); 2251 if (!write) 2252 entry = pte_wrprotect(entry); 2253 if (!young) 2254 entry = pte_mkold(entry); 2255 if (soft_dirty) 2256 entry = pte_mksoft_dirty(entry); 2257 } 2258 pte = pte_offset_map(&_pmd, addr); 2259 BUG_ON(!pte_none(*pte)); 2260 set_pte_at(mm, addr, pte, entry); 2261 atomic_inc(&page[i]._mapcount); 2262 pte_unmap(pte); 2263 } 2264 2265 /* 2266 * Set PG_double_map before dropping compound_mapcount to avoid 2267 * false-negative page_mapped(). 2268 */ 2269 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { 2270 for (i = 0; i < HPAGE_PMD_NR; i++) 2271 atomic_inc(&page[i]._mapcount); 2272 } 2273 2274 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { 2275 /* Last compound_mapcount is gone. */ 2276 __dec_node_page_state(page, NR_ANON_THPS); 2277 if (TestClearPageDoubleMap(page)) { 2278 /* No need in mapcount reference anymore */ 2279 for (i = 0; i < HPAGE_PMD_NR; i++) 2280 atomic_dec(&page[i]._mapcount); 2281 } 2282 } 2283 2284 smp_wmb(); /* make pte visible before pmd */ 2285 pmd_populate(mm, pmd, pgtable); 2286 2287 if (freeze) { 2288 for (i = 0; i < HPAGE_PMD_NR; i++) { 2289 page_remove_rmap(page + i, false); 2290 put_page(page + i); 2291 } 2292 } 2293 } 2294 2295 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2296 unsigned long address, bool freeze, struct page *page) 2297 { 2298 spinlock_t *ptl; 2299 struct mmu_notifier_range range; 2300 2301 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2302 address & HPAGE_PMD_MASK, 2303 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2304 mmu_notifier_invalidate_range_start(&range); 2305 ptl = pmd_lock(vma->vm_mm, pmd); 2306 2307 /* 2308 * If caller asks to setup a migration entries, we need a page to check 2309 * pmd against. Otherwise we can end up replacing wrong page. 2310 */ 2311 VM_BUG_ON(freeze && !page); 2312 if (page && page != pmd_page(*pmd)) 2313 goto out; 2314 2315 if (pmd_trans_huge(*pmd)) { 2316 page = pmd_page(*pmd); 2317 if (PageMlocked(page)) 2318 clear_page_mlock(page); 2319 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd))) 2320 goto out; 2321 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2322 out: 2323 spin_unlock(ptl); 2324 /* 2325 * No need to double call mmu_notifier->invalidate_range() callback. 2326 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2327 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2328 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2329 * fault will trigger a flush_notify before pointing to a new page 2330 * (it is fine if the secondary mmu keeps pointing to the old zero 2331 * page in the meantime) 2332 * 3) Split a huge pmd into pte pointing to the same page. No need 2333 * to invalidate secondary tlb entry they are all still valid. 2334 * any further changes to individual pte will notify. So no need 2335 * to call mmu_notifier->invalidate_range() 2336 */ 2337 mmu_notifier_invalidate_range_only_end(&range); 2338 } 2339 2340 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2341 bool freeze, struct page *page) 2342 { 2343 pgd_t *pgd; 2344 p4d_t *p4d; 2345 pud_t *pud; 2346 pmd_t *pmd; 2347 2348 pgd = pgd_offset(vma->vm_mm, address); 2349 if (!pgd_present(*pgd)) 2350 return; 2351 2352 p4d = p4d_offset(pgd, address); 2353 if (!p4d_present(*p4d)) 2354 return; 2355 2356 pud = pud_offset(p4d, address); 2357 if (!pud_present(*pud)) 2358 return; 2359 2360 pmd = pmd_offset(pud, address); 2361 2362 __split_huge_pmd(vma, pmd, address, freeze, page); 2363 } 2364 2365 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2366 unsigned long start, 2367 unsigned long end, 2368 long adjust_next) 2369 { 2370 /* 2371 * If the new start address isn't hpage aligned and it could 2372 * previously contain an hugepage: check if we need to split 2373 * an huge pmd. 2374 */ 2375 if (start & ~HPAGE_PMD_MASK && 2376 (start & HPAGE_PMD_MASK) >= vma->vm_start && 2377 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2378 split_huge_pmd_address(vma, start, false, NULL); 2379 2380 /* 2381 * If the new end address isn't hpage aligned and it could 2382 * previously contain an hugepage: check if we need to split 2383 * an huge pmd. 2384 */ 2385 if (end & ~HPAGE_PMD_MASK && 2386 (end & HPAGE_PMD_MASK) >= vma->vm_start && 2387 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2388 split_huge_pmd_address(vma, end, false, NULL); 2389 2390 /* 2391 * If we're also updating the vma->vm_next->vm_start, if the new 2392 * vm_next->vm_start isn't page aligned and it could previously 2393 * contain an hugepage: check if we need to split an huge pmd. 2394 */ 2395 if (adjust_next > 0) { 2396 struct vm_area_struct *next = vma->vm_next; 2397 unsigned long nstart = next->vm_start; 2398 nstart += adjust_next << PAGE_SHIFT; 2399 if (nstart & ~HPAGE_PMD_MASK && 2400 (nstart & HPAGE_PMD_MASK) >= next->vm_start && 2401 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) 2402 split_huge_pmd_address(next, nstart, false, NULL); 2403 } 2404 } 2405 2406 static void unmap_page(struct page *page) 2407 { 2408 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | 2409 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD; 2410 bool unmap_success; 2411 2412 VM_BUG_ON_PAGE(!PageHead(page), page); 2413 2414 if (PageAnon(page)) 2415 ttu_flags |= TTU_SPLIT_FREEZE; 2416 2417 unmap_success = try_to_unmap(page, ttu_flags); 2418 VM_BUG_ON_PAGE(!unmap_success, page); 2419 } 2420 2421 static void remap_page(struct page *page) 2422 { 2423 int i; 2424 if (PageTransHuge(page)) { 2425 remove_migration_ptes(page, page, true); 2426 } else { 2427 for (i = 0; i < HPAGE_PMD_NR; i++) 2428 remove_migration_ptes(page + i, page + i, true); 2429 } 2430 } 2431 2432 static void __split_huge_page_tail(struct page *head, int tail, 2433 struct lruvec *lruvec, struct list_head *list) 2434 { 2435 struct page *page_tail = head + tail; 2436 2437 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2438 2439 /* 2440 * Clone page flags before unfreezing refcount. 2441 * 2442 * After successful get_page_unless_zero() might follow flags change, 2443 * for exmaple lock_page() which set PG_waiters. 2444 */ 2445 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2446 page_tail->flags |= (head->flags & 2447 ((1L << PG_referenced) | 2448 (1L << PG_swapbacked) | 2449 (1L << PG_swapcache) | 2450 (1L << PG_mlocked) | 2451 (1L << PG_uptodate) | 2452 (1L << PG_active) | 2453 (1L << PG_workingset) | 2454 (1L << PG_locked) | 2455 (1L << PG_unevictable) | 2456 (1L << PG_dirty))); 2457 2458 /* ->mapping in first tail page is compound_mapcount */ 2459 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2460 page_tail); 2461 page_tail->mapping = head->mapping; 2462 page_tail->index = head->index + tail; 2463 2464 /* Page flags must be visible before we make the page non-compound. */ 2465 smp_wmb(); 2466 2467 /* 2468 * Clear PageTail before unfreezing page refcount. 2469 * 2470 * After successful get_page_unless_zero() might follow put_page() 2471 * which needs correct compound_head(). 2472 */ 2473 clear_compound_head(page_tail); 2474 2475 /* Finally unfreeze refcount. Additional reference from page cache. */ 2476 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2477 PageSwapCache(head))); 2478 2479 if (page_is_young(head)) 2480 set_page_young(page_tail); 2481 if (page_is_idle(head)) 2482 set_page_idle(page_tail); 2483 2484 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2485 2486 /* 2487 * always add to the tail because some iterators expect new 2488 * pages to show after the currently processed elements - e.g. 2489 * migrate_pages 2490 */ 2491 lru_add_page_tail(head, page_tail, lruvec, list); 2492 } 2493 2494 static void __split_huge_page(struct page *page, struct list_head *list, 2495 pgoff_t end, unsigned long flags) 2496 { 2497 struct page *head = compound_head(page); 2498 pg_data_t *pgdat = page_pgdat(head); 2499 struct lruvec *lruvec; 2500 int i; 2501 2502 lruvec = mem_cgroup_page_lruvec(head, pgdat); 2503 2504 /* complete memcg works before add pages to LRU */ 2505 mem_cgroup_split_huge_fixup(head); 2506 2507 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { 2508 __split_huge_page_tail(head, i, lruvec, list); 2509 /* Some pages can be beyond i_size: drop them from page cache */ 2510 if (head[i].index >= end) { 2511 ClearPageDirty(head + i); 2512 __delete_from_page_cache(head + i, NULL); 2513 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) 2514 shmem_uncharge(head->mapping->host, 1); 2515 put_page(head + i); 2516 } 2517 } 2518 2519 ClearPageCompound(head); 2520 2521 split_page_owner(head, HPAGE_PMD_ORDER); 2522 2523 /* See comment in __split_huge_page_tail() */ 2524 if (PageAnon(head)) { 2525 /* Additional pin to swap cache */ 2526 if (PageSwapCache(head)) 2527 page_ref_add(head, 2); 2528 else 2529 page_ref_inc(head); 2530 } else { 2531 /* Additional pin to page cache */ 2532 page_ref_add(head, 2); 2533 xa_unlock(&head->mapping->i_pages); 2534 } 2535 2536 spin_unlock_irqrestore(&pgdat->lru_lock, flags); 2537 2538 remap_page(head); 2539 2540 for (i = 0; i < HPAGE_PMD_NR; i++) { 2541 struct page *subpage = head + i; 2542 if (subpage == page) 2543 continue; 2544 unlock_page(subpage); 2545 2546 /* 2547 * Subpages may be freed if there wasn't any mapping 2548 * like if add_to_swap() is running on a lru page that 2549 * had its mapping zapped. And freeing these pages 2550 * requires taking the lru_lock so we do the put_page 2551 * of the tail pages after the split is complete. 2552 */ 2553 put_page(subpage); 2554 } 2555 } 2556 2557 int total_mapcount(struct page *page) 2558 { 2559 int i, compound, ret; 2560 2561 VM_BUG_ON_PAGE(PageTail(page), page); 2562 2563 if (likely(!PageCompound(page))) 2564 return atomic_read(&page->_mapcount) + 1; 2565 2566 compound = compound_mapcount(page); 2567 if (PageHuge(page)) 2568 return compound; 2569 ret = compound; 2570 for (i = 0; i < HPAGE_PMD_NR; i++) 2571 ret += atomic_read(&page[i]._mapcount) + 1; 2572 /* File pages has compound_mapcount included in _mapcount */ 2573 if (!PageAnon(page)) 2574 return ret - compound * HPAGE_PMD_NR; 2575 if (PageDoubleMap(page)) 2576 ret -= HPAGE_PMD_NR; 2577 return ret; 2578 } 2579 2580 /* 2581 * This calculates accurately how many mappings a transparent hugepage 2582 * has (unlike page_mapcount() which isn't fully accurate). This full 2583 * accuracy is primarily needed to know if copy-on-write faults can 2584 * reuse the page and change the mapping to read-write instead of 2585 * copying them. At the same time this returns the total_mapcount too. 2586 * 2587 * The function returns the highest mapcount any one of the subpages 2588 * has. If the return value is one, even if different processes are 2589 * mapping different subpages of the transparent hugepage, they can 2590 * all reuse it, because each process is reusing a different subpage. 2591 * 2592 * The total_mapcount is instead counting all virtual mappings of the 2593 * subpages. If the total_mapcount is equal to "one", it tells the 2594 * caller all mappings belong to the same "mm" and in turn the 2595 * anon_vma of the transparent hugepage can become the vma->anon_vma 2596 * local one as no other process may be mapping any of the subpages. 2597 * 2598 * It would be more accurate to replace page_mapcount() with 2599 * page_trans_huge_mapcount(), however we only use 2600 * page_trans_huge_mapcount() in the copy-on-write faults where we 2601 * need full accuracy to avoid breaking page pinning, because 2602 * page_trans_huge_mapcount() is slower than page_mapcount(). 2603 */ 2604 int page_trans_huge_mapcount(struct page *page, int *total_mapcount) 2605 { 2606 int i, ret, _total_mapcount, mapcount; 2607 2608 /* hugetlbfs shouldn't call it */ 2609 VM_BUG_ON_PAGE(PageHuge(page), page); 2610 2611 if (likely(!PageTransCompound(page))) { 2612 mapcount = atomic_read(&page->_mapcount) + 1; 2613 if (total_mapcount) 2614 *total_mapcount = mapcount; 2615 return mapcount; 2616 } 2617 2618 page = compound_head(page); 2619 2620 _total_mapcount = ret = 0; 2621 for (i = 0; i < HPAGE_PMD_NR; i++) { 2622 mapcount = atomic_read(&page[i]._mapcount) + 1; 2623 ret = max(ret, mapcount); 2624 _total_mapcount += mapcount; 2625 } 2626 if (PageDoubleMap(page)) { 2627 ret -= 1; 2628 _total_mapcount -= HPAGE_PMD_NR; 2629 } 2630 mapcount = compound_mapcount(page); 2631 ret += mapcount; 2632 _total_mapcount += mapcount; 2633 if (total_mapcount) 2634 *total_mapcount = _total_mapcount; 2635 return ret; 2636 } 2637 2638 /* Racy check whether the huge page can be split */ 2639 bool can_split_huge_page(struct page *page, int *pextra_pins) 2640 { 2641 int extra_pins; 2642 2643 /* Additional pins from page cache */ 2644 if (PageAnon(page)) 2645 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0; 2646 else 2647 extra_pins = HPAGE_PMD_NR; 2648 if (pextra_pins) 2649 *pextra_pins = extra_pins; 2650 return total_mapcount(page) == page_count(page) - extra_pins - 1; 2651 } 2652 2653 /* 2654 * This function splits huge page into normal pages. @page can point to any 2655 * subpage of huge page to split. Split doesn't change the position of @page. 2656 * 2657 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2658 * The huge page must be locked. 2659 * 2660 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2661 * 2662 * Both head page and tail pages will inherit mapping, flags, and so on from 2663 * the hugepage. 2664 * 2665 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2666 * they are not mapped. 2667 * 2668 * Returns 0 if the hugepage is split successfully. 2669 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2670 * us. 2671 */ 2672 int split_huge_page_to_list(struct page *page, struct list_head *list) 2673 { 2674 struct page *head = compound_head(page); 2675 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); 2676 struct anon_vma *anon_vma = NULL; 2677 struct address_space *mapping = NULL; 2678 int count, mapcount, extra_pins, ret; 2679 bool mlocked; 2680 unsigned long flags; 2681 pgoff_t end; 2682 2683 VM_BUG_ON_PAGE(is_huge_zero_page(page), page); 2684 VM_BUG_ON_PAGE(!PageLocked(page), page); 2685 VM_BUG_ON_PAGE(!PageCompound(page), page); 2686 2687 if (PageWriteback(page)) 2688 return -EBUSY; 2689 2690 if (PageAnon(head)) { 2691 /* 2692 * The caller does not necessarily hold an mmap_sem that would 2693 * prevent the anon_vma disappearing so we first we take a 2694 * reference to it and then lock the anon_vma for write. This 2695 * is similar to page_lock_anon_vma_read except the write lock 2696 * is taken to serialise against parallel split or collapse 2697 * operations. 2698 */ 2699 anon_vma = page_get_anon_vma(head); 2700 if (!anon_vma) { 2701 ret = -EBUSY; 2702 goto out; 2703 } 2704 end = -1; 2705 mapping = NULL; 2706 anon_vma_lock_write(anon_vma); 2707 } else { 2708 mapping = head->mapping; 2709 2710 /* Truncated ? */ 2711 if (!mapping) { 2712 ret = -EBUSY; 2713 goto out; 2714 } 2715 2716 anon_vma = NULL; 2717 i_mmap_lock_read(mapping); 2718 2719 /* 2720 *__split_huge_page() may need to trim off pages beyond EOF: 2721 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2722 * which cannot be nested inside the page tree lock. So note 2723 * end now: i_size itself may be changed at any moment, but 2724 * head page lock is good enough to serialize the trimming. 2725 */ 2726 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2727 } 2728 2729 /* 2730 * Racy check if we can split the page, before unmap_page() will 2731 * split PMDs 2732 */ 2733 if (!can_split_huge_page(head, &extra_pins)) { 2734 ret = -EBUSY; 2735 goto out_unlock; 2736 } 2737 2738 mlocked = PageMlocked(page); 2739 unmap_page(head); 2740 VM_BUG_ON_PAGE(compound_mapcount(head), head); 2741 2742 /* Make sure the page is not on per-CPU pagevec as it takes pin */ 2743 if (mlocked) 2744 lru_add_drain(); 2745 2746 /* prevent PageLRU to go away from under us, and freeze lru stats */ 2747 spin_lock_irqsave(&pgdata->lru_lock, flags); 2748 2749 if (mapping) { 2750 XA_STATE(xas, &mapping->i_pages, page_index(head)); 2751 2752 /* 2753 * Check if the head page is present in page cache. 2754 * We assume all tail are present too, if head is there. 2755 */ 2756 xa_lock(&mapping->i_pages); 2757 if (xas_load(&xas) != head) 2758 goto fail; 2759 } 2760 2761 /* Prevent deferred_split_scan() touching ->_refcount */ 2762 spin_lock(&pgdata->split_queue_lock); 2763 count = page_count(head); 2764 mapcount = total_mapcount(head); 2765 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) { 2766 if (!list_empty(page_deferred_list(head))) { 2767 pgdata->split_queue_len--; 2768 list_del(page_deferred_list(head)); 2769 } 2770 if (mapping) 2771 __dec_node_page_state(page, NR_SHMEM_THPS); 2772 spin_unlock(&pgdata->split_queue_lock); 2773 __split_huge_page(page, list, end, flags); 2774 if (PageSwapCache(head)) { 2775 swp_entry_t entry = { .val = page_private(head) }; 2776 2777 ret = split_swap_cluster(entry); 2778 } else 2779 ret = 0; 2780 } else { 2781 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { 2782 pr_alert("total_mapcount: %u, page_count(): %u\n", 2783 mapcount, count); 2784 if (PageTail(page)) 2785 dump_page(head, NULL); 2786 dump_page(page, "total_mapcount(head) > 0"); 2787 BUG(); 2788 } 2789 spin_unlock(&pgdata->split_queue_lock); 2790 fail: if (mapping) 2791 xa_unlock(&mapping->i_pages); 2792 spin_unlock_irqrestore(&pgdata->lru_lock, flags); 2793 remap_page(head); 2794 ret = -EBUSY; 2795 } 2796 2797 out_unlock: 2798 if (anon_vma) { 2799 anon_vma_unlock_write(anon_vma); 2800 put_anon_vma(anon_vma); 2801 } 2802 if (mapping) 2803 i_mmap_unlock_read(mapping); 2804 out: 2805 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2806 return ret; 2807 } 2808 2809 void free_transhuge_page(struct page *page) 2810 { 2811 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); 2812 unsigned long flags; 2813 2814 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2815 if (!list_empty(page_deferred_list(page))) { 2816 pgdata->split_queue_len--; 2817 list_del(page_deferred_list(page)); 2818 } 2819 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2820 free_compound_page(page); 2821 } 2822 2823 void deferred_split_huge_page(struct page *page) 2824 { 2825 struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); 2826 unsigned long flags; 2827 2828 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2829 2830 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2831 if (list_empty(page_deferred_list(page))) { 2832 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2833 list_add_tail(page_deferred_list(page), &pgdata->split_queue); 2834 pgdata->split_queue_len++; 2835 } 2836 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2837 } 2838 2839 static unsigned long deferred_split_count(struct shrinker *shrink, 2840 struct shrink_control *sc) 2841 { 2842 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2843 return READ_ONCE(pgdata->split_queue_len); 2844 } 2845 2846 static unsigned long deferred_split_scan(struct shrinker *shrink, 2847 struct shrink_control *sc) 2848 { 2849 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2850 unsigned long flags; 2851 LIST_HEAD(list), *pos, *next; 2852 struct page *page; 2853 int split = 0; 2854 2855 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2856 /* Take pin on all head pages to avoid freeing them under us */ 2857 list_for_each_safe(pos, next, &pgdata->split_queue) { 2858 page = list_entry((void *)pos, struct page, mapping); 2859 page = compound_head(page); 2860 if (get_page_unless_zero(page)) { 2861 list_move(page_deferred_list(page), &list); 2862 } else { 2863 /* We lost race with put_compound_page() */ 2864 list_del_init(page_deferred_list(page)); 2865 pgdata->split_queue_len--; 2866 } 2867 if (!--sc->nr_to_scan) 2868 break; 2869 } 2870 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2871 2872 list_for_each_safe(pos, next, &list) { 2873 page = list_entry((void *)pos, struct page, mapping); 2874 if (!trylock_page(page)) 2875 goto next; 2876 /* split_huge_page() removes page from list on success */ 2877 if (!split_huge_page(page)) 2878 split++; 2879 unlock_page(page); 2880 next: 2881 put_page(page); 2882 } 2883 2884 spin_lock_irqsave(&pgdata->split_queue_lock, flags); 2885 list_splice_tail(&list, &pgdata->split_queue); 2886 spin_unlock_irqrestore(&pgdata->split_queue_lock, flags); 2887 2888 /* 2889 * Stop shrinker if we didn't split any page, but the queue is empty. 2890 * This can happen if pages were freed under us. 2891 */ 2892 if (!split && list_empty(&pgdata->split_queue)) 2893 return SHRINK_STOP; 2894 return split; 2895 } 2896 2897 static struct shrinker deferred_split_shrinker = { 2898 .count_objects = deferred_split_count, 2899 .scan_objects = deferred_split_scan, 2900 .seeks = DEFAULT_SEEKS, 2901 .flags = SHRINKER_NUMA_AWARE, 2902 }; 2903 2904 #ifdef CONFIG_DEBUG_FS 2905 static int split_huge_pages_set(void *data, u64 val) 2906 { 2907 struct zone *zone; 2908 struct page *page; 2909 unsigned long pfn, max_zone_pfn; 2910 unsigned long total = 0, split = 0; 2911 2912 if (val != 1) 2913 return -EINVAL; 2914 2915 for_each_populated_zone(zone) { 2916 max_zone_pfn = zone_end_pfn(zone); 2917 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 2918 if (!pfn_valid(pfn)) 2919 continue; 2920 2921 page = pfn_to_page(pfn); 2922 if (!get_page_unless_zero(page)) 2923 continue; 2924 2925 if (zone != page_zone(page)) 2926 goto next; 2927 2928 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 2929 goto next; 2930 2931 total++; 2932 lock_page(page); 2933 if (!split_huge_page(page)) 2934 split++; 2935 unlock_page(page); 2936 next: 2937 put_page(page); 2938 } 2939 } 2940 2941 pr_info("%lu of %lu THP split\n", split, total); 2942 2943 return 0; 2944 } 2945 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, 2946 "%llu\n"); 2947 2948 static int __init split_huge_pages_debugfs(void) 2949 { 2950 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 2951 &split_huge_pages_fops); 2952 return 0; 2953 } 2954 late_initcall(split_huge_pages_debugfs); 2955 #endif 2956 2957 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 2958 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 2959 struct page *page) 2960 { 2961 struct vm_area_struct *vma = pvmw->vma; 2962 struct mm_struct *mm = vma->vm_mm; 2963 unsigned long address = pvmw->address; 2964 pmd_t pmdval; 2965 swp_entry_t entry; 2966 pmd_t pmdswp; 2967 2968 if (!(pvmw->pmd && !pvmw->pte)) 2969 return; 2970 2971 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 2972 pmdval = *pvmw->pmd; 2973 pmdp_invalidate(vma, address, pvmw->pmd); 2974 if (pmd_dirty(pmdval)) 2975 set_page_dirty(page); 2976 entry = make_migration_entry(page, pmd_write(pmdval)); 2977 pmdswp = swp_entry_to_pmd(entry); 2978 if (pmd_soft_dirty(pmdval)) 2979 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 2980 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 2981 page_remove_rmap(page, true); 2982 put_page(page); 2983 } 2984 2985 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 2986 { 2987 struct vm_area_struct *vma = pvmw->vma; 2988 struct mm_struct *mm = vma->vm_mm; 2989 unsigned long address = pvmw->address; 2990 unsigned long mmun_start = address & HPAGE_PMD_MASK; 2991 pmd_t pmde; 2992 swp_entry_t entry; 2993 2994 if (!(pvmw->pmd && !pvmw->pte)) 2995 return; 2996 2997 entry = pmd_to_swp_entry(*pvmw->pmd); 2998 get_page(new); 2999 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot)); 3000 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3001 pmde = pmd_mksoft_dirty(pmde); 3002 if (is_write_migration_entry(entry)) 3003 pmde = maybe_pmd_mkwrite(pmde, vma); 3004 3005 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE); 3006 if (PageAnon(new)) 3007 page_add_anon_rmap(new, vma, mmun_start, true); 3008 else 3009 page_add_file_rmap(new, true); 3010 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde); 3011 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new)) 3012 mlock_vma_page(new); 3013 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3014 } 3015 #endif 3016