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 #ifdef CONFIG_MEMCG 500 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 501 { 502 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup; 503 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 504 505 if (memcg) 506 return &memcg->deferred_split_queue; 507 else 508 return &pgdat->deferred_split_queue; 509 } 510 #else 511 static inline struct deferred_split *get_deferred_split_queue(struct page *page) 512 { 513 struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); 514 515 return &pgdat->deferred_split_queue; 516 } 517 #endif 518 519 void prep_transhuge_page(struct page *page) 520 { 521 /* 522 * we use page->mapping and page->indexlru in second tail page 523 * as list_head: assuming THP order >= 2 524 */ 525 526 INIT_LIST_HEAD(page_deferred_list(page)); 527 set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR); 528 } 529 530 bool is_transparent_hugepage(struct page *page) 531 { 532 if (!PageCompound(page)) 533 return 0; 534 535 page = compound_head(page); 536 return is_huge_zero_page(page) || 537 page[1].compound_dtor == TRANSHUGE_PAGE_DTOR; 538 } 539 EXPORT_SYMBOL_GPL(is_transparent_hugepage); 540 541 static unsigned long __thp_get_unmapped_area(struct file *filp, 542 unsigned long addr, unsigned long len, 543 loff_t off, unsigned long flags, unsigned long size) 544 { 545 loff_t off_end = off + len; 546 loff_t off_align = round_up(off, size); 547 unsigned long len_pad, ret; 548 549 if (off_end <= off_align || (off_end - off_align) < size) 550 return 0; 551 552 len_pad = len + size; 553 if (len_pad < len || (off + len_pad) < off) 554 return 0; 555 556 ret = current->mm->get_unmapped_area(filp, addr, len_pad, 557 off >> PAGE_SHIFT, flags); 558 559 /* 560 * The failure might be due to length padding. The caller will retry 561 * without the padding. 562 */ 563 if (IS_ERR_VALUE(ret)) 564 return 0; 565 566 /* 567 * Do not try to align to THP boundary if allocation at the address 568 * hint succeeds. 569 */ 570 if (ret == addr) 571 return addr; 572 573 ret += (off - ret) & (size - 1); 574 return ret; 575 } 576 577 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, 578 unsigned long len, unsigned long pgoff, unsigned long flags) 579 { 580 unsigned long ret; 581 loff_t off = (loff_t)pgoff << PAGE_SHIFT; 582 583 if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD)) 584 goto out; 585 586 ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE); 587 if (ret) 588 return ret; 589 out: 590 return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); 591 } 592 EXPORT_SYMBOL_GPL(thp_get_unmapped_area); 593 594 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 595 struct page *page, gfp_t gfp) 596 { 597 struct vm_area_struct *vma = vmf->vma; 598 struct mem_cgroup *memcg; 599 pgtable_t pgtable; 600 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 601 vm_fault_t ret = 0; 602 603 VM_BUG_ON_PAGE(!PageCompound(page), page); 604 605 if (mem_cgroup_try_charge_delay(page, vma->vm_mm, gfp, &memcg, true)) { 606 put_page(page); 607 count_vm_event(THP_FAULT_FALLBACK); 608 return VM_FAULT_FALLBACK; 609 } 610 611 pgtable = pte_alloc_one(vma->vm_mm); 612 if (unlikely(!pgtable)) { 613 ret = VM_FAULT_OOM; 614 goto release; 615 } 616 617 clear_huge_page(page, vmf->address, HPAGE_PMD_NR); 618 /* 619 * The memory barrier inside __SetPageUptodate makes sure that 620 * clear_huge_page writes become visible before the set_pmd_at() 621 * write. 622 */ 623 __SetPageUptodate(page); 624 625 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 626 if (unlikely(!pmd_none(*vmf->pmd))) { 627 goto unlock_release; 628 } else { 629 pmd_t entry; 630 631 ret = check_stable_address_space(vma->vm_mm); 632 if (ret) 633 goto unlock_release; 634 635 /* Deliver the page fault to userland */ 636 if (userfaultfd_missing(vma)) { 637 vm_fault_t ret2; 638 639 spin_unlock(vmf->ptl); 640 mem_cgroup_cancel_charge(page, memcg, true); 641 put_page(page); 642 pte_free(vma->vm_mm, pgtable); 643 ret2 = handle_userfault(vmf, VM_UFFD_MISSING); 644 VM_BUG_ON(ret2 & VM_FAULT_FALLBACK); 645 return ret2; 646 } 647 648 entry = mk_huge_pmd(page, vma->vm_page_prot); 649 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 650 page_add_new_anon_rmap(page, vma, haddr, true); 651 mem_cgroup_commit_charge(page, memcg, false, true); 652 lru_cache_add_active_or_unevictable(page, vma); 653 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable); 654 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 655 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 656 mm_inc_nr_ptes(vma->vm_mm); 657 spin_unlock(vmf->ptl); 658 count_vm_event(THP_FAULT_ALLOC); 659 count_memcg_events(memcg, THP_FAULT_ALLOC, 1); 660 } 661 662 return 0; 663 unlock_release: 664 spin_unlock(vmf->ptl); 665 release: 666 if (pgtable) 667 pte_free(vma->vm_mm, pgtable); 668 mem_cgroup_cancel_charge(page, memcg, true); 669 put_page(page); 670 return ret; 671 672 } 673 674 /* 675 * always: directly stall for all thp allocations 676 * defer: wake kswapd and fail if not immediately available 677 * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise 678 * fail if not immediately available 679 * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately 680 * available 681 * never: never stall for any thp allocation 682 */ 683 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma) 684 { 685 const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE); 686 687 /* Always do synchronous compaction */ 688 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags)) 689 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY); 690 691 /* Kick kcompactd and fail quickly */ 692 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags)) 693 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM; 694 695 /* Synchronous compaction if madvised, otherwise kick kcompactd */ 696 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags)) 697 return GFP_TRANSHUGE_LIGHT | 698 (vma_madvised ? __GFP_DIRECT_RECLAIM : 699 __GFP_KSWAPD_RECLAIM); 700 701 /* Only do synchronous compaction if madvised */ 702 if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags)) 703 return GFP_TRANSHUGE_LIGHT | 704 (vma_madvised ? __GFP_DIRECT_RECLAIM : 0); 705 706 return GFP_TRANSHUGE_LIGHT; 707 } 708 709 /* Caller must hold page table lock. */ 710 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, 711 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd, 712 struct page *zero_page) 713 { 714 pmd_t entry; 715 if (!pmd_none(*pmd)) 716 return false; 717 entry = mk_pmd(zero_page, vma->vm_page_prot); 718 entry = pmd_mkhuge(entry); 719 if (pgtable) 720 pgtable_trans_huge_deposit(mm, pmd, pgtable); 721 set_pmd_at(mm, haddr, pmd, entry); 722 mm_inc_nr_ptes(mm); 723 return true; 724 } 725 726 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf) 727 { 728 struct vm_area_struct *vma = vmf->vma; 729 gfp_t gfp; 730 struct page *page; 731 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 732 733 if (!transhuge_vma_suitable(vma, haddr)) 734 return VM_FAULT_FALLBACK; 735 if (unlikely(anon_vma_prepare(vma))) 736 return VM_FAULT_OOM; 737 if (unlikely(khugepaged_enter(vma, vma->vm_flags))) 738 return VM_FAULT_OOM; 739 if (!(vmf->flags & FAULT_FLAG_WRITE) && 740 !mm_forbids_zeropage(vma->vm_mm) && 741 transparent_hugepage_use_zero_page()) { 742 pgtable_t pgtable; 743 struct page *zero_page; 744 bool set; 745 vm_fault_t ret; 746 pgtable = pte_alloc_one(vma->vm_mm); 747 if (unlikely(!pgtable)) 748 return VM_FAULT_OOM; 749 zero_page = mm_get_huge_zero_page(vma->vm_mm); 750 if (unlikely(!zero_page)) { 751 pte_free(vma->vm_mm, pgtable); 752 count_vm_event(THP_FAULT_FALLBACK); 753 return VM_FAULT_FALLBACK; 754 } 755 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 756 ret = 0; 757 set = false; 758 if (pmd_none(*vmf->pmd)) { 759 ret = check_stable_address_space(vma->vm_mm); 760 if (ret) { 761 spin_unlock(vmf->ptl); 762 } else if (userfaultfd_missing(vma)) { 763 spin_unlock(vmf->ptl); 764 ret = handle_userfault(vmf, VM_UFFD_MISSING); 765 VM_BUG_ON(ret & VM_FAULT_FALLBACK); 766 } else { 767 set_huge_zero_page(pgtable, vma->vm_mm, vma, 768 haddr, vmf->pmd, zero_page); 769 spin_unlock(vmf->ptl); 770 set = true; 771 } 772 } else 773 spin_unlock(vmf->ptl); 774 if (!set) 775 pte_free(vma->vm_mm, pgtable); 776 return ret; 777 } 778 gfp = alloc_hugepage_direct_gfpmask(vma); 779 page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER); 780 if (unlikely(!page)) { 781 count_vm_event(THP_FAULT_FALLBACK); 782 return VM_FAULT_FALLBACK; 783 } 784 prep_transhuge_page(page); 785 return __do_huge_pmd_anonymous_page(vmf, page, gfp); 786 } 787 788 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr, 789 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write, 790 pgtable_t pgtable) 791 { 792 struct mm_struct *mm = vma->vm_mm; 793 pmd_t entry; 794 spinlock_t *ptl; 795 796 ptl = pmd_lock(mm, pmd); 797 if (!pmd_none(*pmd)) { 798 if (write) { 799 if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) { 800 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd)); 801 goto out_unlock; 802 } 803 entry = pmd_mkyoung(*pmd); 804 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 805 if (pmdp_set_access_flags(vma, addr, pmd, entry, 1)) 806 update_mmu_cache_pmd(vma, addr, pmd); 807 } 808 809 goto out_unlock; 810 } 811 812 entry = pmd_mkhuge(pfn_t_pmd(pfn, prot)); 813 if (pfn_t_devmap(pfn)) 814 entry = pmd_mkdevmap(entry); 815 if (write) { 816 entry = pmd_mkyoung(pmd_mkdirty(entry)); 817 entry = maybe_pmd_mkwrite(entry, vma); 818 } 819 820 if (pgtable) { 821 pgtable_trans_huge_deposit(mm, pmd, pgtable); 822 mm_inc_nr_ptes(mm); 823 pgtable = NULL; 824 } 825 826 set_pmd_at(mm, addr, pmd, entry); 827 update_mmu_cache_pmd(vma, addr, pmd); 828 829 out_unlock: 830 spin_unlock(ptl); 831 if (pgtable) 832 pte_free(mm, pgtable); 833 } 834 835 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write) 836 { 837 unsigned long addr = vmf->address & PMD_MASK; 838 struct vm_area_struct *vma = vmf->vma; 839 pgprot_t pgprot = vma->vm_page_prot; 840 pgtable_t pgtable = NULL; 841 842 /* 843 * If we had pmd_special, we could avoid all these restrictions, 844 * but we need to be consistent with PTEs and architectures that 845 * can't support a 'special' bit. 846 */ 847 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 848 !pfn_t_devmap(pfn)); 849 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 850 (VM_PFNMAP|VM_MIXEDMAP)); 851 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 852 853 if (addr < vma->vm_start || addr >= vma->vm_end) 854 return VM_FAULT_SIGBUS; 855 856 if (arch_needs_pgtable_deposit()) { 857 pgtable = pte_alloc_one(vma->vm_mm); 858 if (!pgtable) 859 return VM_FAULT_OOM; 860 } 861 862 track_pfn_insert(vma, &pgprot, pfn); 863 864 insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable); 865 return VM_FAULT_NOPAGE; 866 } 867 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd); 868 869 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 870 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma) 871 { 872 if (likely(vma->vm_flags & VM_WRITE)) 873 pud = pud_mkwrite(pud); 874 return pud; 875 } 876 877 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr, 878 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write) 879 { 880 struct mm_struct *mm = vma->vm_mm; 881 pud_t entry; 882 spinlock_t *ptl; 883 884 ptl = pud_lock(mm, pud); 885 if (!pud_none(*pud)) { 886 if (write) { 887 if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) { 888 WARN_ON_ONCE(!is_huge_zero_pud(*pud)); 889 goto out_unlock; 890 } 891 entry = pud_mkyoung(*pud); 892 entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma); 893 if (pudp_set_access_flags(vma, addr, pud, entry, 1)) 894 update_mmu_cache_pud(vma, addr, pud); 895 } 896 goto out_unlock; 897 } 898 899 entry = pud_mkhuge(pfn_t_pud(pfn, prot)); 900 if (pfn_t_devmap(pfn)) 901 entry = pud_mkdevmap(entry); 902 if (write) { 903 entry = pud_mkyoung(pud_mkdirty(entry)); 904 entry = maybe_pud_mkwrite(entry, vma); 905 } 906 set_pud_at(mm, addr, pud, entry); 907 update_mmu_cache_pud(vma, addr, pud); 908 909 out_unlock: 910 spin_unlock(ptl); 911 } 912 913 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write) 914 { 915 unsigned long addr = vmf->address & PUD_MASK; 916 struct vm_area_struct *vma = vmf->vma; 917 pgprot_t pgprot = vma->vm_page_prot; 918 919 /* 920 * If we had pud_special, we could avoid all these restrictions, 921 * but we need to be consistent with PTEs and architectures that 922 * can't support a 'special' bit. 923 */ 924 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 925 !pfn_t_devmap(pfn)); 926 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 927 (VM_PFNMAP|VM_MIXEDMAP)); 928 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 929 930 if (addr < vma->vm_start || addr >= vma->vm_end) 931 return VM_FAULT_SIGBUS; 932 933 track_pfn_insert(vma, &pgprot, pfn); 934 935 insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write); 936 return VM_FAULT_NOPAGE; 937 } 938 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud); 939 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 940 941 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr, 942 pmd_t *pmd, int flags) 943 { 944 pmd_t _pmd; 945 946 _pmd = pmd_mkyoung(*pmd); 947 if (flags & FOLL_WRITE) 948 _pmd = pmd_mkdirty(_pmd); 949 if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK, 950 pmd, _pmd, flags & FOLL_WRITE)) 951 update_mmu_cache_pmd(vma, addr, pmd); 952 } 953 954 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr, 955 pmd_t *pmd, int flags, struct dev_pagemap **pgmap) 956 { 957 unsigned long pfn = pmd_pfn(*pmd); 958 struct mm_struct *mm = vma->vm_mm; 959 struct page *page; 960 961 assert_spin_locked(pmd_lockptr(mm, pmd)); 962 963 /* 964 * When we COW a devmap PMD entry, we split it into PTEs, so we should 965 * not be in this function with `flags & FOLL_COW` set. 966 */ 967 WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set"); 968 969 if (flags & FOLL_WRITE && !pmd_write(*pmd)) 970 return NULL; 971 972 if (pmd_present(*pmd) && pmd_devmap(*pmd)) 973 /* pass */; 974 else 975 return NULL; 976 977 if (flags & FOLL_TOUCH) 978 touch_pmd(vma, addr, pmd, flags); 979 980 /* 981 * device mapped pages can only be returned if the 982 * caller will manage the page reference count. 983 */ 984 if (!(flags & FOLL_GET)) 985 return ERR_PTR(-EEXIST); 986 987 pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT; 988 *pgmap = get_dev_pagemap(pfn, *pgmap); 989 if (!*pgmap) 990 return ERR_PTR(-EFAULT); 991 page = pfn_to_page(pfn); 992 get_page(page); 993 994 return page; 995 } 996 997 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 998 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr, 999 struct vm_area_struct *vma) 1000 { 1001 spinlock_t *dst_ptl, *src_ptl; 1002 struct page *src_page; 1003 pmd_t pmd; 1004 pgtable_t pgtable = NULL; 1005 int ret = -ENOMEM; 1006 1007 /* Skip if can be re-fill on fault */ 1008 if (!vma_is_anonymous(vma)) 1009 return 0; 1010 1011 pgtable = pte_alloc_one(dst_mm); 1012 if (unlikely(!pgtable)) 1013 goto out; 1014 1015 dst_ptl = pmd_lock(dst_mm, dst_pmd); 1016 src_ptl = pmd_lockptr(src_mm, src_pmd); 1017 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1018 1019 ret = -EAGAIN; 1020 pmd = *src_pmd; 1021 1022 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1023 if (unlikely(is_swap_pmd(pmd))) { 1024 swp_entry_t entry = pmd_to_swp_entry(pmd); 1025 1026 VM_BUG_ON(!is_pmd_migration_entry(pmd)); 1027 if (is_write_migration_entry(entry)) { 1028 make_migration_entry_read(&entry); 1029 pmd = swp_entry_to_pmd(entry); 1030 if (pmd_swp_soft_dirty(*src_pmd)) 1031 pmd = pmd_swp_mksoft_dirty(pmd); 1032 set_pmd_at(src_mm, addr, src_pmd, pmd); 1033 } 1034 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1035 mm_inc_nr_ptes(dst_mm); 1036 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1037 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1038 ret = 0; 1039 goto out_unlock; 1040 } 1041 #endif 1042 1043 if (unlikely(!pmd_trans_huge(pmd))) { 1044 pte_free(dst_mm, pgtable); 1045 goto out_unlock; 1046 } 1047 /* 1048 * When page table lock is held, the huge zero pmd should not be 1049 * under splitting since we don't split the page itself, only pmd to 1050 * a page table. 1051 */ 1052 if (is_huge_zero_pmd(pmd)) { 1053 struct page *zero_page; 1054 /* 1055 * get_huge_zero_page() will never allocate a new page here, 1056 * since we already have a zero page to copy. It just takes a 1057 * reference. 1058 */ 1059 zero_page = mm_get_huge_zero_page(dst_mm); 1060 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd, 1061 zero_page); 1062 ret = 0; 1063 goto out_unlock; 1064 } 1065 1066 src_page = pmd_page(pmd); 1067 VM_BUG_ON_PAGE(!PageHead(src_page), src_page); 1068 get_page(src_page); 1069 page_dup_rmap(src_page, true); 1070 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1071 mm_inc_nr_ptes(dst_mm); 1072 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); 1073 1074 pmdp_set_wrprotect(src_mm, addr, src_pmd); 1075 pmd = pmd_mkold(pmd_wrprotect(pmd)); 1076 set_pmd_at(dst_mm, addr, dst_pmd, pmd); 1077 1078 ret = 0; 1079 out_unlock: 1080 spin_unlock(src_ptl); 1081 spin_unlock(dst_ptl); 1082 out: 1083 return ret; 1084 } 1085 1086 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 1087 static void touch_pud(struct vm_area_struct *vma, unsigned long addr, 1088 pud_t *pud, int flags) 1089 { 1090 pud_t _pud; 1091 1092 _pud = pud_mkyoung(*pud); 1093 if (flags & FOLL_WRITE) 1094 _pud = pud_mkdirty(_pud); 1095 if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK, 1096 pud, _pud, flags & FOLL_WRITE)) 1097 update_mmu_cache_pud(vma, addr, pud); 1098 } 1099 1100 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr, 1101 pud_t *pud, int flags, struct dev_pagemap **pgmap) 1102 { 1103 unsigned long pfn = pud_pfn(*pud); 1104 struct mm_struct *mm = vma->vm_mm; 1105 struct page *page; 1106 1107 assert_spin_locked(pud_lockptr(mm, pud)); 1108 1109 if (flags & FOLL_WRITE && !pud_write(*pud)) 1110 return NULL; 1111 1112 if (pud_present(*pud) && pud_devmap(*pud)) 1113 /* pass */; 1114 else 1115 return NULL; 1116 1117 if (flags & FOLL_TOUCH) 1118 touch_pud(vma, addr, pud, flags); 1119 1120 /* 1121 * device mapped pages can only be returned if the 1122 * caller will manage the page reference count. 1123 */ 1124 if (!(flags & FOLL_GET)) 1125 return ERR_PTR(-EEXIST); 1126 1127 pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT; 1128 *pgmap = get_dev_pagemap(pfn, *pgmap); 1129 if (!*pgmap) 1130 return ERR_PTR(-EFAULT); 1131 page = pfn_to_page(pfn); 1132 get_page(page); 1133 1134 return page; 1135 } 1136 1137 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1138 pud_t *dst_pud, pud_t *src_pud, unsigned long addr, 1139 struct vm_area_struct *vma) 1140 { 1141 spinlock_t *dst_ptl, *src_ptl; 1142 pud_t pud; 1143 int ret; 1144 1145 dst_ptl = pud_lock(dst_mm, dst_pud); 1146 src_ptl = pud_lockptr(src_mm, src_pud); 1147 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1148 1149 ret = -EAGAIN; 1150 pud = *src_pud; 1151 if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud))) 1152 goto out_unlock; 1153 1154 /* 1155 * When page table lock is held, the huge zero pud should not be 1156 * under splitting since we don't split the page itself, only pud to 1157 * a page table. 1158 */ 1159 if (is_huge_zero_pud(pud)) { 1160 /* No huge zero pud yet */ 1161 } 1162 1163 pudp_set_wrprotect(src_mm, addr, src_pud); 1164 pud = pud_mkold(pud_wrprotect(pud)); 1165 set_pud_at(dst_mm, addr, dst_pud, pud); 1166 1167 ret = 0; 1168 out_unlock: 1169 spin_unlock(src_ptl); 1170 spin_unlock(dst_ptl); 1171 return ret; 1172 } 1173 1174 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud) 1175 { 1176 pud_t entry; 1177 unsigned long haddr; 1178 bool write = vmf->flags & FAULT_FLAG_WRITE; 1179 1180 vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud); 1181 if (unlikely(!pud_same(*vmf->pud, orig_pud))) 1182 goto unlock; 1183 1184 entry = pud_mkyoung(orig_pud); 1185 if (write) 1186 entry = pud_mkdirty(entry); 1187 haddr = vmf->address & HPAGE_PUD_MASK; 1188 if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write)) 1189 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud); 1190 1191 unlock: 1192 spin_unlock(vmf->ptl); 1193 } 1194 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 1195 1196 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd) 1197 { 1198 pmd_t entry; 1199 unsigned long haddr; 1200 bool write = vmf->flags & FAULT_FLAG_WRITE; 1201 1202 vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd); 1203 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1204 goto unlock; 1205 1206 entry = pmd_mkyoung(orig_pmd); 1207 if (write) 1208 entry = pmd_mkdirty(entry); 1209 haddr = vmf->address & HPAGE_PMD_MASK; 1210 if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write)) 1211 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd); 1212 1213 unlock: 1214 spin_unlock(vmf->ptl); 1215 } 1216 1217 static vm_fault_t do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, 1218 pmd_t orig_pmd, struct page *page) 1219 { 1220 struct vm_area_struct *vma = vmf->vma; 1221 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1222 struct mem_cgroup *memcg; 1223 pgtable_t pgtable; 1224 pmd_t _pmd; 1225 int i; 1226 vm_fault_t ret = 0; 1227 struct page **pages; 1228 struct mmu_notifier_range range; 1229 1230 pages = kmalloc_array(HPAGE_PMD_NR, sizeof(struct page *), 1231 GFP_KERNEL); 1232 if (unlikely(!pages)) { 1233 ret |= VM_FAULT_OOM; 1234 goto out; 1235 } 1236 1237 for (i = 0; i < HPAGE_PMD_NR; i++) { 1238 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma, 1239 vmf->address, page_to_nid(page)); 1240 if (unlikely(!pages[i] || 1241 mem_cgroup_try_charge_delay(pages[i], vma->vm_mm, 1242 GFP_KERNEL, &memcg, false))) { 1243 if (pages[i]) 1244 put_page(pages[i]); 1245 while (--i >= 0) { 1246 memcg = (void *)page_private(pages[i]); 1247 set_page_private(pages[i], 0); 1248 mem_cgroup_cancel_charge(pages[i], memcg, 1249 false); 1250 put_page(pages[i]); 1251 } 1252 kfree(pages); 1253 ret |= VM_FAULT_OOM; 1254 goto out; 1255 } 1256 set_page_private(pages[i], (unsigned long)memcg); 1257 } 1258 1259 for (i = 0; i < HPAGE_PMD_NR; i++) { 1260 copy_user_highpage(pages[i], page + i, 1261 haddr + PAGE_SIZE * i, vma); 1262 __SetPageUptodate(pages[i]); 1263 cond_resched(); 1264 } 1265 1266 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1267 haddr, haddr + HPAGE_PMD_SIZE); 1268 mmu_notifier_invalidate_range_start(&range); 1269 1270 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1271 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1272 goto out_free_pages; 1273 VM_BUG_ON_PAGE(!PageHead(page), page); 1274 1275 /* 1276 * Leave pmd empty until pte is filled note we must notify here as 1277 * concurrent CPU thread might write to new page before the call to 1278 * mmu_notifier_invalidate_range_end() happens which can lead to a 1279 * device seeing memory write in different order than CPU. 1280 * 1281 * See Documentation/vm/mmu_notifier.rst 1282 */ 1283 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); 1284 1285 pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd); 1286 pmd_populate(vma->vm_mm, &_pmd, pgtable); 1287 1288 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 1289 pte_t entry; 1290 entry = mk_pte(pages[i], vma->vm_page_prot); 1291 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1292 memcg = (void *)page_private(pages[i]); 1293 set_page_private(pages[i], 0); 1294 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false); 1295 mem_cgroup_commit_charge(pages[i], memcg, false, false); 1296 lru_cache_add_active_or_unevictable(pages[i], vma); 1297 vmf->pte = pte_offset_map(&_pmd, haddr); 1298 VM_BUG_ON(!pte_none(*vmf->pte)); 1299 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry); 1300 pte_unmap(vmf->pte); 1301 } 1302 kfree(pages); 1303 1304 smp_wmb(); /* make pte visible before pmd */ 1305 pmd_populate(vma->vm_mm, vmf->pmd, pgtable); 1306 page_remove_rmap(page, true); 1307 spin_unlock(vmf->ptl); 1308 1309 /* 1310 * No need to double call mmu_notifier->invalidate_range() callback as 1311 * the above pmdp_huge_clear_flush_notify() did already call it. 1312 */ 1313 mmu_notifier_invalidate_range_only_end(&range); 1314 1315 ret |= VM_FAULT_WRITE; 1316 put_page(page); 1317 1318 out: 1319 return ret; 1320 1321 out_free_pages: 1322 spin_unlock(vmf->ptl); 1323 mmu_notifier_invalidate_range_end(&range); 1324 for (i = 0; i < HPAGE_PMD_NR; i++) { 1325 memcg = (void *)page_private(pages[i]); 1326 set_page_private(pages[i], 0); 1327 mem_cgroup_cancel_charge(pages[i], memcg, false); 1328 put_page(pages[i]); 1329 } 1330 kfree(pages); 1331 goto out; 1332 } 1333 1334 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd) 1335 { 1336 struct vm_area_struct *vma = vmf->vma; 1337 struct page *page = NULL, *new_page; 1338 struct mem_cgroup *memcg; 1339 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1340 struct mmu_notifier_range range; 1341 gfp_t huge_gfp; /* for allocation and charge */ 1342 vm_fault_t ret = 0; 1343 1344 vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd); 1345 VM_BUG_ON_VMA(!vma->anon_vma, vma); 1346 if (is_huge_zero_pmd(orig_pmd)) 1347 goto alloc; 1348 spin_lock(vmf->ptl); 1349 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) 1350 goto out_unlock; 1351 1352 page = pmd_page(orig_pmd); 1353 VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page); 1354 /* 1355 * We can only reuse the page if nobody else maps the huge page or it's 1356 * part. 1357 */ 1358 if (!trylock_page(page)) { 1359 get_page(page); 1360 spin_unlock(vmf->ptl); 1361 lock_page(page); 1362 spin_lock(vmf->ptl); 1363 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1364 unlock_page(page); 1365 put_page(page); 1366 goto out_unlock; 1367 } 1368 put_page(page); 1369 } 1370 if (reuse_swap_page(page, NULL)) { 1371 pmd_t entry; 1372 entry = pmd_mkyoung(orig_pmd); 1373 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1374 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1)) 1375 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1376 ret |= VM_FAULT_WRITE; 1377 unlock_page(page); 1378 goto out_unlock; 1379 } 1380 unlock_page(page); 1381 get_page(page); 1382 spin_unlock(vmf->ptl); 1383 alloc: 1384 if (__transparent_hugepage_enabled(vma) && 1385 !transparent_hugepage_debug_cow()) { 1386 huge_gfp = alloc_hugepage_direct_gfpmask(vma); 1387 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER); 1388 } else 1389 new_page = NULL; 1390 1391 if (likely(new_page)) { 1392 prep_transhuge_page(new_page); 1393 } else { 1394 if (!page) { 1395 split_huge_pmd(vma, vmf->pmd, vmf->address); 1396 ret |= VM_FAULT_FALLBACK; 1397 } else { 1398 ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page); 1399 if (ret & VM_FAULT_OOM) { 1400 split_huge_pmd(vma, vmf->pmd, vmf->address); 1401 ret |= VM_FAULT_FALLBACK; 1402 } 1403 put_page(page); 1404 } 1405 count_vm_event(THP_FAULT_FALLBACK); 1406 goto out; 1407 } 1408 1409 if (unlikely(mem_cgroup_try_charge_delay(new_page, vma->vm_mm, 1410 huge_gfp, &memcg, true))) { 1411 put_page(new_page); 1412 split_huge_pmd(vma, vmf->pmd, vmf->address); 1413 if (page) 1414 put_page(page); 1415 ret |= VM_FAULT_FALLBACK; 1416 count_vm_event(THP_FAULT_FALLBACK); 1417 goto out; 1418 } 1419 1420 count_vm_event(THP_FAULT_ALLOC); 1421 count_memcg_events(memcg, THP_FAULT_ALLOC, 1); 1422 1423 if (!page) 1424 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR); 1425 else 1426 copy_user_huge_page(new_page, page, vmf->address, 1427 vma, HPAGE_PMD_NR); 1428 __SetPageUptodate(new_page); 1429 1430 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 1431 haddr, haddr + HPAGE_PMD_SIZE); 1432 mmu_notifier_invalidate_range_start(&range); 1433 1434 spin_lock(vmf->ptl); 1435 if (page) 1436 put_page(page); 1437 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) { 1438 spin_unlock(vmf->ptl); 1439 mem_cgroup_cancel_charge(new_page, memcg, true); 1440 put_page(new_page); 1441 goto out_mn; 1442 } else { 1443 pmd_t entry; 1444 entry = mk_huge_pmd(new_page, vma->vm_page_prot); 1445 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 1446 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd); 1447 page_add_new_anon_rmap(new_page, vma, haddr, true); 1448 mem_cgroup_commit_charge(new_page, memcg, false, true); 1449 lru_cache_add_active_or_unevictable(new_page, vma); 1450 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 1451 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1452 if (!page) { 1453 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); 1454 } else { 1455 VM_BUG_ON_PAGE(!PageHead(page), page); 1456 page_remove_rmap(page, true); 1457 put_page(page); 1458 } 1459 ret |= VM_FAULT_WRITE; 1460 } 1461 spin_unlock(vmf->ptl); 1462 out_mn: 1463 /* 1464 * No need to double call mmu_notifier->invalidate_range() callback as 1465 * the above pmdp_huge_clear_flush_notify() did already call it. 1466 */ 1467 mmu_notifier_invalidate_range_only_end(&range); 1468 out: 1469 return ret; 1470 out_unlock: 1471 spin_unlock(vmf->ptl); 1472 return ret; 1473 } 1474 1475 /* 1476 * FOLL_FORCE can write to even unwritable pmd's, but only 1477 * after we've gone through a COW cycle and they are dirty. 1478 */ 1479 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) 1480 { 1481 return pmd_write(pmd) || 1482 ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); 1483 } 1484 1485 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 1486 unsigned long addr, 1487 pmd_t *pmd, 1488 unsigned int flags) 1489 { 1490 struct mm_struct *mm = vma->vm_mm; 1491 struct page *page = NULL; 1492 1493 assert_spin_locked(pmd_lockptr(mm, pmd)); 1494 1495 if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags)) 1496 goto out; 1497 1498 /* Avoid dumping huge zero page */ 1499 if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd)) 1500 return ERR_PTR(-EFAULT); 1501 1502 /* Full NUMA hinting faults to serialise migration in fault paths */ 1503 if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) 1504 goto out; 1505 1506 page = pmd_page(*pmd); 1507 VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page); 1508 if (flags & FOLL_TOUCH) 1509 touch_pmd(vma, addr, pmd, flags); 1510 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { 1511 /* 1512 * We don't mlock() pte-mapped THPs. This way we can avoid 1513 * leaking mlocked pages into non-VM_LOCKED VMAs. 1514 * 1515 * For anon THP: 1516 * 1517 * In most cases the pmd is the only mapping of the page as we 1518 * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for 1519 * writable private mappings in populate_vma_page_range(). 1520 * 1521 * The only scenario when we have the page shared here is if we 1522 * mlocking read-only mapping shared over fork(). We skip 1523 * mlocking such pages. 1524 * 1525 * For file THP: 1526 * 1527 * We can expect PageDoubleMap() to be stable under page lock: 1528 * for file pages we set it in page_add_file_rmap(), which 1529 * requires page to be locked. 1530 */ 1531 1532 if (PageAnon(page) && compound_mapcount(page) != 1) 1533 goto skip_mlock; 1534 if (PageDoubleMap(page) || !page->mapping) 1535 goto skip_mlock; 1536 if (!trylock_page(page)) 1537 goto skip_mlock; 1538 lru_add_drain(); 1539 if (page->mapping && !PageDoubleMap(page)) 1540 mlock_vma_page(page); 1541 unlock_page(page); 1542 } 1543 skip_mlock: 1544 page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; 1545 VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page); 1546 if (flags & FOLL_GET) 1547 get_page(page); 1548 1549 out: 1550 return page; 1551 } 1552 1553 /* NUMA hinting page fault entry point for trans huge pmds */ 1554 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) 1555 { 1556 struct vm_area_struct *vma = vmf->vma; 1557 struct anon_vma *anon_vma = NULL; 1558 struct page *page; 1559 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 1560 int page_nid = NUMA_NO_NODE, this_nid = numa_node_id(); 1561 int target_nid, last_cpupid = -1; 1562 bool page_locked; 1563 bool migrated = false; 1564 bool was_writable; 1565 int flags = 0; 1566 1567 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 1568 if (unlikely(!pmd_same(pmd, *vmf->pmd))) 1569 goto out_unlock; 1570 1571 /* 1572 * If there are potential migrations, wait for completion and retry 1573 * without disrupting NUMA hinting information. Do not relock and 1574 * check_same as the page may no longer be mapped. 1575 */ 1576 if (unlikely(pmd_trans_migrating(*vmf->pmd))) { 1577 page = pmd_page(*vmf->pmd); 1578 if (!get_page_unless_zero(page)) 1579 goto out_unlock; 1580 spin_unlock(vmf->ptl); 1581 put_and_wait_on_page_locked(page); 1582 goto out; 1583 } 1584 1585 page = pmd_page(pmd); 1586 BUG_ON(is_huge_zero_page(page)); 1587 page_nid = page_to_nid(page); 1588 last_cpupid = page_cpupid_last(page); 1589 count_vm_numa_event(NUMA_HINT_FAULTS); 1590 if (page_nid == this_nid) { 1591 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 1592 flags |= TNF_FAULT_LOCAL; 1593 } 1594 1595 /* See similar comment in do_numa_page for explanation */ 1596 if (!pmd_savedwrite(pmd)) 1597 flags |= TNF_NO_GROUP; 1598 1599 /* 1600 * Acquire the page lock to serialise THP migrations but avoid dropping 1601 * page_table_lock if at all possible 1602 */ 1603 page_locked = trylock_page(page); 1604 target_nid = mpol_misplaced(page, vma, haddr); 1605 if (target_nid == NUMA_NO_NODE) { 1606 /* If the page was locked, there are no parallel migrations */ 1607 if (page_locked) 1608 goto clear_pmdnuma; 1609 } 1610 1611 /* Migration could have started since the pmd_trans_migrating check */ 1612 if (!page_locked) { 1613 page_nid = NUMA_NO_NODE; 1614 if (!get_page_unless_zero(page)) 1615 goto out_unlock; 1616 spin_unlock(vmf->ptl); 1617 put_and_wait_on_page_locked(page); 1618 goto out; 1619 } 1620 1621 /* 1622 * Page is misplaced. Page lock serialises migrations. Acquire anon_vma 1623 * to serialises splits 1624 */ 1625 get_page(page); 1626 spin_unlock(vmf->ptl); 1627 anon_vma = page_lock_anon_vma_read(page); 1628 1629 /* Confirm the PMD did not change while page_table_lock was released */ 1630 spin_lock(vmf->ptl); 1631 if (unlikely(!pmd_same(pmd, *vmf->pmd))) { 1632 unlock_page(page); 1633 put_page(page); 1634 page_nid = NUMA_NO_NODE; 1635 goto out_unlock; 1636 } 1637 1638 /* Bail if we fail to protect against THP splits for any reason */ 1639 if (unlikely(!anon_vma)) { 1640 put_page(page); 1641 page_nid = NUMA_NO_NODE; 1642 goto clear_pmdnuma; 1643 } 1644 1645 /* 1646 * Since we took the NUMA fault, we must have observed the !accessible 1647 * bit. Make sure all other CPUs agree with that, to avoid them 1648 * modifying the page we're about to migrate. 1649 * 1650 * Must be done under PTL such that we'll observe the relevant 1651 * inc_tlb_flush_pending(). 1652 * 1653 * We are not sure a pending tlb flush here is for a huge page 1654 * mapping or not. Hence use the tlb range variant 1655 */ 1656 if (mm_tlb_flush_pending(vma->vm_mm)) { 1657 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE); 1658 /* 1659 * change_huge_pmd() released the pmd lock before 1660 * invalidating the secondary MMUs sharing the primary 1661 * MMU pagetables (with ->invalidate_range()). The 1662 * mmu_notifier_invalidate_range_end() (which 1663 * internally calls ->invalidate_range()) in 1664 * change_pmd_range() will run after us, so we can't 1665 * rely on it here and we need an explicit invalidate. 1666 */ 1667 mmu_notifier_invalidate_range(vma->vm_mm, haddr, 1668 haddr + HPAGE_PMD_SIZE); 1669 } 1670 1671 /* 1672 * Migrate the THP to the requested node, returns with page unlocked 1673 * and access rights restored. 1674 */ 1675 spin_unlock(vmf->ptl); 1676 1677 migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma, 1678 vmf->pmd, pmd, vmf->address, page, target_nid); 1679 if (migrated) { 1680 flags |= TNF_MIGRATED; 1681 page_nid = target_nid; 1682 } else 1683 flags |= TNF_MIGRATE_FAIL; 1684 1685 goto out; 1686 clear_pmdnuma: 1687 BUG_ON(!PageLocked(page)); 1688 was_writable = pmd_savedwrite(pmd); 1689 pmd = pmd_modify(pmd, vma->vm_page_prot); 1690 pmd = pmd_mkyoung(pmd); 1691 if (was_writable) 1692 pmd = pmd_mkwrite(pmd); 1693 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd); 1694 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd); 1695 unlock_page(page); 1696 out_unlock: 1697 spin_unlock(vmf->ptl); 1698 1699 out: 1700 if (anon_vma) 1701 page_unlock_anon_vma_read(anon_vma); 1702 1703 if (page_nid != NUMA_NO_NODE) 1704 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR, 1705 flags); 1706 1707 return 0; 1708 } 1709 1710 /* 1711 * Return true if we do MADV_FREE successfully on entire pmd page. 1712 * Otherwise, return false. 1713 */ 1714 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1715 pmd_t *pmd, unsigned long addr, unsigned long next) 1716 { 1717 spinlock_t *ptl; 1718 pmd_t orig_pmd; 1719 struct page *page; 1720 struct mm_struct *mm = tlb->mm; 1721 bool ret = false; 1722 1723 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1724 1725 ptl = pmd_trans_huge_lock(pmd, vma); 1726 if (!ptl) 1727 goto out_unlocked; 1728 1729 orig_pmd = *pmd; 1730 if (is_huge_zero_pmd(orig_pmd)) 1731 goto out; 1732 1733 if (unlikely(!pmd_present(orig_pmd))) { 1734 VM_BUG_ON(thp_migration_supported() && 1735 !is_pmd_migration_entry(orig_pmd)); 1736 goto out; 1737 } 1738 1739 page = pmd_page(orig_pmd); 1740 /* 1741 * If other processes are mapping this page, we couldn't discard 1742 * the page unless they all do MADV_FREE so let's skip the page. 1743 */ 1744 if (page_mapcount(page) != 1) 1745 goto out; 1746 1747 if (!trylock_page(page)) 1748 goto out; 1749 1750 /* 1751 * If user want to discard part-pages of THP, split it so MADV_FREE 1752 * will deactivate only them. 1753 */ 1754 if (next - addr != HPAGE_PMD_SIZE) { 1755 get_page(page); 1756 spin_unlock(ptl); 1757 split_huge_page(page); 1758 unlock_page(page); 1759 put_page(page); 1760 goto out_unlocked; 1761 } 1762 1763 if (PageDirty(page)) 1764 ClearPageDirty(page); 1765 unlock_page(page); 1766 1767 if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) { 1768 pmdp_invalidate(vma, addr, pmd); 1769 orig_pmd = pmd_mkold(orig_pmd); 1770 orig_pmd = pmd_mkclean(orig_pmd); 1771 1772 set_pmd_at(mm, addr, pmd, orig_pmd); 1773 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1774 } 1775 1776 mark_page_lazyfree(page); 1777 ret = true; 1778 out: 1779 spin_unlock(ptl); 1780 out_unlocked: 1781 return ret; 1782 } 1783 1784 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 1785 { 1786 pgtable_t pgtable; 1787 1788 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 1789 pte_free(mm, pgtable); 1790 mm_dec_nr_ptes(mm); 1791 } 1792 1793 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 1794 pmd_t *pmd, unsigned long addr) 1795 { 1796 pmd_t orig_pmd; 1797 spinlock_t *ptl; 1798 1799 tlb_change_page_size(tlb, HPAGE_PMD_SIZE); 1800 1801 ptl = __pmd_trans_huge_lock(pmd, vma); 1802 if (!ptl) 1803 return 0; 1804 /* 1805 * For architectures like ppc64 we look at deposited pgtable 1806 * when calling pmdp_huge_get_and_clear. So do the 1807 * pgtable_trans_huge_withdraw after finishing pmdp related 1808 * operations. 1809 */ 1810 orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd, 1811 tlb->fullmm); 1812 tlb_remove_pmd_tlb_entry(tlb, pmd, addr); 1813 if (vma_is_dax(vma)) { 1814 if (arch_needs_pgtable_deposit()) 1815 zap_deposited_table(tlb->mm, pmd); 1816 spin_unlock(ptl); 1817 if (is_huge_zero_pmd(orig_pmd)) 1818 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1819 } else if (is_huge_zero_pmd(orig_pmd)) { 1820 zap_deposited_table(tlb->mm, pmd); 1821 spin_unlock(ptl); 1822 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE); 1823 } else { 1824 struct page *page = NULL; 1825 int flush_needed = 1; 1826 1827 if (pmd_present(orig_pmd)) { 1828 page = pmd_page(orig_pmd); 1829 page_remove_rmap(page, true); 1830 VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); 1831 VM_BUG_ON_PAGE(!PageHead(page), page); 1832 } else if (thp_migration_supported()) { 1833 swp_entry_t entry; 1834 1835 VM_BUG_ON(!is_pmd_migration_entry(orig_pmd)); 1836 entry = pmd_to_swp_entry(orig_pmd); 1837 page = pfn_to_page(swp_offset(entry)); 1838 flush_needed = 0; 1839 } else 1840 WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!"); 1841 1842 if (PageAnon(page)) { 1843 zap_deposited_table(tlb->mm, pmd); 1844 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR); 1845 } else { 1846 if (arch_needs_pgtable_deposit()) 1847 zap_deposited_table(tlb->mm, pmd); 1848 add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); 1849 } 1850 1851 spin_unlock(ptl); 1852 if (flush_needed) 1853 tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE); 1854 } 1855 return 1; 1856 } 1857 1858 #ifndef pmd_move_must_withdraw 1859 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl, 1860 spinlock_t *old_pmd_ptl, 1861 struct vm_area_struct *vma) 1862 { 1863 /* 1864 * With split pmd lock we also need to move preallocated 1865 * PTE page table if new_pmd is on different PMD page table. 1866 * 1867 * We also don't deposit and withdraw tables for file pages. 1868 */ 1869 return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma); 1870 } 1871 #endif 1872 1873 static pmd_t move_soft_dirty_pmd(pmd_t pmd) 1874 { 1875 #ifdef CONFIG_MEM_SOFT_DIRTY 1876 if (unlikely(is_pmd_migration_entry(pmd))) 1877 pmd = pmd_swp_mksoft_dirty(pmd); 1878 else if (pmd_present(pmd)) 1879 pmd = pmd_mksoft_dirty(pmd); 1880 #endif 1881 return pmd; 1882 } 1883 1884 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr, 1885 unsigned long new_addr, unsigned long old_end, 1886 pmd_t *old_pmd, pmd_t *new_pmd) 1887 { 1888 spinlock_t *old_ptl, *new_ptl; 1889 pmd_t pmd; 1890 struct mm_struct *mm = vma->vm_mm; 1891 bool force_flush = false; 1892 1893 if ((old_addr & ~HPAGE_PMD_MASK) || 1894 (new_addr & ~HPAGE_PMD_MASK) || 1895 old_end - old_addr < HPAGE_PMD_SIZE) 1896 return false; 1897 1898 /* 1899 * The destination pmd shouldn't be established, free_pgtables() 1900 * should have release it. 1901 */ 1902 if (WARN_ON(!pmd_none(*new_pmd))) { 1903 VM_BUG_ON(pmd_trans_huge(*new_pmd)); 1904 return false; 1905 } 1906 1907 /* 1908 * We don't have to worry about the ordering of src and dst 1909 * ptlocks because exclusive mmap_sem prevents deadlock. 1910 */ 1911 old_ptl = __pmd_trans_huge_lock(old_pmd, vma); 1912 if (old_ptl) { 1913 new_ptl = pmd_lockptr(mm, new_pmd); 1914 if (new_ptl != old_ptl) 1915 spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); 1916 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd); 1917 if (pmd_present(pmd)) 1918 force_flush = true; 1919 VM_BUG_ON(!pmd_none(*new_pmd)); 1920 1921 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) { 1922 pgtable_t pgtable; 1923 pgtable = pgtable_trans_huge_withdraw(mm, old_pmd); 1924 pgtable_trans_huge_deposit(mm, new_pmd, pgtable); 1925 } 1926 pmd = move_soft_dirty_pmd(pmd); 1927 set_pmd_at(mm, new_addr, new_pmd, pmd); 1928 if (force_flush) 1929 flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); 1930 if (new_ptl != old_ptl) 1931 spin_unlock(new_ptl); 1932 spin_unlock(old_ptl); 1933 return true; 1934 } 1935 return false; 1936 } 1937 1938 /* 1939 * Returns 1940 * - 0 if PMD could not be locked 1941 * - 1 if PMD was locked but protections unchange and TLB flush unnecessary 1942 * - HPAGE_PMD_NR is protections changed and TLB flush necessary 1943 */ 1944 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 1945 unsigned long addr, pgprot_t newprot, int prot_numa) 1946 { 1947 struct mm_struct *mm = vma->vm_mm; 1948 spinlock_t *ptl; 1949 pmd_t entry; 1950 bool preserve_write; 1951 int ret; 1952 1953 ptl = __pmd_trans_huge_lock(pmd, vma); 1954 if (!ptl) 1955 return 0; 1956 1957 preserve_write = prot_numa && pmd_write(*pmd); 1958 ret = 1; 1959 1960 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 1961 if (is_swap_pmd(*pmd)) { 1962 swp_entry_t entry = pmd_to_swp_entry(*pmd); 1963 1964 VM_BUG_ON(!is_pmd_migration_entry(*pmd)); 1965 if (is_write_migration_entry(entry)) { 1966 pmd_t newpmd; 1967 /* 1968 * A protection check is difficult so 1969 * just be safe and disable write 1970 */ 1971 make_migration_entry_read(&entry); 1972 newpmd = swp_entry_to_pmd(entry); 1973 if (pmd_swp_soft_dirty(*pmd)) 1974 newpmd = pmd_swp_mksoft_dirty(newpmd); 1975 set_pmd_at(mm, addr, pmd, newpmd); 1976 } 1977 goto unlock; 1978 } 1979 #endif 1980 1981 /* 1982 * Avoid trapping faults against the zero page. The read-only 1983 * data is likely to be read-cached on the local CPU and 1984 * local/remote hits to the zero page are not interesting. 1985 */ 1986 if (prot_numa && is_huge_zero_pmd(*pmd)) 1987 goto unlock; 1988 1989 if (prot_numa && pmd_protnone(*pmd)) 1990 goto unlock; 1991 1992 /* 1993 * In case prot_numa, we are under down_read(mmap_sem). It's critical 1994 * to not clear pmd intermittently to avoid race with MADV_DONTNEED 1995 * which is also under down_read(mmap_sem): 1996 * 1997 * CPU0: CPU1: 1998 * change_huge_pmd(prot_numa=1) 1999 * pmdp_huge_get_and_clear_notify() 2000 * madvise_dontneed() 2001 * zap_pmd_range() 2002 * pmd_trans_huge(*pmd) == 0 (without ptl) 2003 * // skip the pmd 2004 * set_pmd_at(); 2005 * // pmd is re-established 2006 * 2007 * The race makes MADV_DONTNEED miss the huge pmd and don't clear it 2008 * which may break userspace. 2009 * 2010 * pmdp_invalidate() is required to make sure we don't miss 2011 * dirty/young flags set by hardware. 2012 */ 2013 entry = pmdp_invalidate(vma, addr, pmd); 2014 2015 entry = pmd_modify(entry, newprot); 2016 if (preserve_write) 2017 entry = pmd_mk_savedwrite(entry); 2018 ret = HPAGE_PMD_NR; 2019 set_pmd_at(mm, addr, pmd, entry); 2020 BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry)); 2021 unlock: 2022 spin_unlock(ptl); 2023 return ret; 2024 } 2025 2026 /* 2027 * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise. 2028 * 2029 * Note that if it returns page table lock pointer, this routine returns without 2030 * unlocking page table lock. So callers must unlock it. 2031 */ 2032 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma) 2033 { 2034 spinlock_t *ptl; 2035 ptl = pmd_lock(vma->vm_mm, pmd); 2036 if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || 2037 pmd_devmap(*pmd))) 2038 return ptl; 2039 spin_unlock(ptl); 2040 return NULL; 2041 } 2042 2043 /* 2044 * Returns true if a given pud maps a thp, false otherwise. 2045 * 2046 * Note that if it returns true, this routine returns without unlocking page 2047 * table lock. So callers must unlock it. 2048 */ 2049 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) 2050 { 2051 spinlock_t *ptl; 2052 2053 ptl = pud_lock(vma->vm_mm, pud); 2054 if (likely(pud_trans_huge(*pud) || pud_devmap(*pud))) 2055 return ptl; 2056 spin_unlock(ptl); 2057 return NULL; 2058 } 2059 2060 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD 2061 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, 2062 pud_t *pud, unsigned long addr) 2063 { 2064 spinlock_t *ptl; 2065 2066 ptl = __pud_trans_huge_lock(pud, vma); 2067 if (!ptl) 2068 return 0; 2069 /* 2070 * For architectures like ppc64 we look at deposited pgtable 2071 * when calling pudp_huge_get_and_clear. So do the 2072 * pgtable_trans_huge_withdraw after finishing pudp related 2073 * operations. 2074 */ 2075 pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); 2076 tlb_remove_pud_tlb_entry(tlb, pud, addr); 2077 if (vma_is_dax(vma)) { 2078 spin_unlock(ptl); 2079 /* No zero page support yet */ 2080 } else { 2081 /* No support for anonymous PUD pages yet */ 2082 BUG(); 2083 } 2084 return 1; 2085 } 2086 2087 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud, 2088 unsigned long haddr) 2089 { 2090 VM_BUG_ON(haddr & ~HPAGE_PUD_MASK); 2091 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2092 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma); 2093 VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud)); 2094 2095 count_vm_event(THP_SPLIT_PUD); 2096 2097 pudp_huge_clear_flush_notify(vma, haddr, pud); 2098 } 2099 2100 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud, 2101 unsigned long address) 2102 { 2103 spinlock_t *ptl; 2104 struct mmu_notifier_range range; 2105 2106 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2107 address & HPAGE_PUD_MASK, 2108 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE); 2109 mmu_notifier_invalidate_range_start(&range); 2110 ptl = pud_lock(vma->vm_mm, pud); 2111 if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud))) 2112 goto out; 2113 __split_huge_pud_locked(vma, pud, range.start); 2114 2115 out: 2116 spin_unlock(ptl); 2117 /* 2118 * No need to double call mmu_notifier->invalidate_range() callback as 2119 * the above pudp_huge_clear_flush_notify() did already call it. 2120 */ 2121 mmu_notifier_invalidate_range_only_end(&range); 2122 } 2123 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 2124 2125 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma, 2126 unsigned long haddr, pmd_t *pmd) 2127 { 2128 struct mm_struct *mm = vma->vm_mm; 2129 pgtable_t pgtable; 2130 pmd_t _pmd; 2131 int i; 2132 2133 /* 2134 * Leave pmd empty until pte is filled note that it is fine to delay 2135 * notification until mmu_notifier_invalidate_range_end() as we are 2136 * replacing a zero pmd write protected page with a zero pte write 2137 * protected page. 2138 * 2139 * See Documentation/vm/mmu_notifier.rst 2140 */ 2141 pmdp_huge_clear_flush(vma, haddr, pmd); 2142 2143 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2144 pmd_populate(mm, &_pmd, pgtable); 2145 2146 for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { 2147 pte_t *pte, entry; 2148 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot); 2149 entry = pte_mkspecial(entry); 2150 pte = pte_offset_map(&_pmd, haddr); 2151 VM_BUG_ON(!pte_none(*pte)); 2152 set_pte_at(mm, haddr, pte, entry); 2153 pte_unmap(pte); 2154 } 2155 smp_wmb(); /* make pte visible before pmd */ 2156 pmd_populate(mm, pmd, pgtable); 2157 } 2158 2159 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 2160 unsigned long haddr, bool freeze) 2161 { 2162 struct mm_struct *mm = vma->vm_mm; 2163 struct page *page; 2164 pgtable_t pgtable; 2165 pmd_t old_pmd, _pmd; 2166 bool young, write, soft_dirty, pmd_migration = false; 2167 unsigned long addr; 2168 int i; 2169 2170 VM_BUG_ON(haddr & ~HPAGE_PMD_MASK); 2171 VM_BUG_ON_VMA(vma->vm_start > haddr, vma); 2172 VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); 2173 VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) 2174 && !pmd_devmap(*pmd)); 2175 2176 count_vm_event(THP_SPLIT_PMD); 2177 2178 if (!vma_is_anonymous(vma)) { 2179 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); 2180 /* 2181 * We are going to unmap this huge page. So 2182 * just go ahead and zap it 2183 */ 2184 if (arch_needs_pgtable_deposit()) 2185 zap_deposited_table(mm, pmd); 2186 if (vma_is_dax(vma)) 2187 return; 2188 page = pmd_page(_pmd); 2189 if (!PageDirty(page) && pmd_dirty(_pmd)) 2190 set_page_dirty(page); 2191 if (!PageReferenced(page) && pmd_young(_pmd)) 2192 SetPageReferenced(page); 2193 page_remove_rmap(page, true); 2194 put_page(page); 2195 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); 2196 return; 2197 } else if (is_huge_zero_pmd(*pmd)) { 2198 /* 2199 * FIXME: Do we want to invalidate secondary mmu by calling 2200 * mmu_notifier_invalidate_range() see comments below inside 2201 * __split_huge_pmd() ? 2202 * 2203 * We are going from a zero huge page write protected to zero 2204 * small page also write protected so it does not seems useful 2205 * to invalidate secondary mmu at this time. 2206 */ 2207 return __split_huge_zero_page_pmd(vma, haddr, pmd); 2208 } 2209 2210 /* 2211 * Up to this point the pmd is present and huge and userland has the 2212 * whole access to the hugepage during the split (which happens in 2213 * place). If we overwrite the pmd with the not-huge version pointing 2214 * to the pte here (which of course we could if all CPUs were bug 2215 * free), userland could trigger a small page size TLB miss on the 2216 * small sized TLB while the hugepage TLB entry is still established in 2217 * the huge TLB. Some CPU doesn't like that. 2218 * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum 2219 * 383 on page 93. Intel should be safe but is also warns that it's 2220 * only safe if the permission and cache attributes of the two entries 2221 * loaded in the two TLB is identical (which should be the case here). 2222 * But it is generally safer to never allow small and huge TLB entries 2223 * for the same virtual address to be loaded simultaneously. So instead 2224 * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the 2225 * current pmd notpresent (atomically because here the pmd_trans_huge 2226 * must remain set at all times on the pmd until the split is complete 2227 * for this pmd), then we flush the SMP TLB and finally we write the 2228 * non-huge version of the pmd entry with pmd_populate. 2229 */ 2230 old_pmd = pmdp_invalidate(vma, haddr, pmd); 2231 2232 pmd_migration = is_pmd_migration_entry(old_pmd); 2233 if (unlikely(pmd_migration)) { 2234 swp_entry_t entry; 2235 2236 entry = pmd_to_swp_entry(old_pmd); 2237 page = pfn_to_page(swp_offset(entry)); 2238 write = is_write_migration_entry(entry); 2239 young = false; 2240 soft_dirty = pmd_swp_soft_dirty(old_pmd); 2241 } else { 2242 page = pmd_page(old_pmd); 2243 if (pmd_dirty(old_pmd)) 2244 SetPageDirty(page); 2245 write = pmd_write(old_pmd); 2246 young = pmd_young(old_pmd); 2247 soft_dirty = pmd_soft_dirty(old_pmd); 2248 } 2249 VM_BUG_ON_PAGE(!page_count(page), page); 2250 page_ref_add(page, HPAGE_PMD_NR - 1); 2251 2252 /* 2253 * Withdraw the table only after we mark the pmd entry invalid. 2254 * This's critical for some architectures (Power). 2255 */ 2256 pgtable = pgtable_trans_huge_withdraw(mm, pmd); 2257 pmd_populate(mm, &_pmd, pgtable); 2258 2259 for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { 2260 pte_t entry, *pte; 2261 /* 2262 * Note that NUMA hinting access restrictions are not 2263 * transferred to avoid any possibility of altering 2264 * permissions across VMAs. 2265 */ 2266 if (freeze || pmd_migration) { 2267 swp_entry_t swp_entry; 2268 swp_entry = make_migration_entry(page + i, write); 2269 entry = swp_entry_to_pte(swp_entry); 2270 if (soft_dirty) 2271 entry = pte_swp_mksoft_dirty(entry); 2272 } else { 2273 entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot)); 2274 entry = maybe_mkwrite(entry, vma); 2275 if (!write) 2276 entry = pte_wrprotect(entry); 2277 if (!young) 2278 entry = pte_mkold(entry); 2279 if (soft_dirty) 2280 entry = pte_mksoft_dirty(entry); 2281 } 2282 pte = pte_offset_map(&_pmd, addr); 2283 BUG_ON(!pte_none(*pte)); 2284 set_pte_at(mm, addr, pte, entry); 2285 atomic_inc(&page[i]._mapcount); 2286 pte_unmap(pte); 2287 } 2288 2289 /* 2290 * Set PG_double_map before dropping compound_mapcount to avoid 2291 * false-negative page_mapped(). 2292 */ 2293 if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { 2294 for (i = 0; i < HPAGE_PMD_NR; i++) 2295 atomic_inc(&page[i]._mapcount); 2296 } 2297 2298 if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { 2299 /* Last compound_mapcount is gone. */ 2300 __dec_node_page_state(page, NR_ANON_THPS); 2301 if (TestClearPageDoubleMap(page)) { 2302 /* No need in mapcount reference anymore */ 2303 for (i = 0; i < HPAGE_PMD_NR; i++) 2304 atomic_dec(&page[i]._mapcount); 2305 } 2306 } 2307 2308 smp_wmb(); /* make pte visible before pmd */ 2309 pmd_populate(mm, pmd, pgtable); 2310 2311 if (freeze) { 2312 for (i = 0; i < HPAGE_PMD_NR; i++) { 2313 page_remove_rmap(page + i, false); 2314 put_page(page + i); 2315 } 2316 } 2317 } 2318 2319 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, 2320 unsigned long address, bool freeze, struct page *page) 2321 { 2322 spinlock_t *ptl; 2323 struct mmu_notifier_range range; 2324 2325 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, 2326 address & HPAGE_PMD_MASK, 2327 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE); 2328 mmu_notifier_invalidate_range_start(&range); 2329 ptl = pmd_lock(vma->vm_mm, pmd); 2330 2331 /* 2332 * If caller asks to setup a migration entries, we need a page to check 2333 * pmd against. Otherwise we can end up replacing wrong page. 2334 */ 2335 VM_BUG_ON(freeze && !page); 2336 if (page && page != pmd_page(*pmd)) 2337 goto out; 2338 2339 if (pmd_trans_huge(*pmd)) { 2340 page = pmd_page(*pmd); 2341 if (PageMlocked(page)) 2342 clear_page_mlock(page); 2343 } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd))) 2344 goto out; 2345 __split_huge_pmd_locked(vma, pmd, range.start, freeze); 2346 out: 2347 spin_unlock(ptl); 2348 /* 2349 * No need to double call mmu_notifier->invalidate_range() callback. 2350 * They are 3 cases to consider inside __split_huge_pmd_locked(): 2351 * 1) pmdp_huge_clear_flush_notify() call invalidate_range() obvious 2352 * 2) __split_huge_zero_page_pmd() read only zero page and any write 2353 * fault will trigger a flush_notify before pointing to a new page 2354 * (it is fine if the secondary mmu keeps pointing to the old zero 2355 * page in the meantime) 2356 * 3) Split a huge pmd into pte pointing to the same page. No need 2357 * to invalidate secondary tlb entry they are all still valid. 2358 * any further changes to individual pte will notify. So no need 2359 * to call mmu_notifier->invalidate_range() 2360 */ 2361 mmu_notifier_invalidate_range_only_end(&range); 2362 } 2363 2364 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address, 2365 bool freeze, struct page *page) 2366 { 2367 pgd_t *pgd; 2368 p4d_t *p4d; 2369 pud_t *pud; 2370 pmd_t *pmd; 2371 2372 pgd = pgd_offset(vma->vm_mm, address); 2373 if (!pgd_present(*pgd)) 2374 return; 2375 2376 p4d = p4d_offset(pgd, address); 2377 if (!p4d_present(*p4d)) 2378 return; 2379 2380 pud = pud_offset(p4d, address); 2381 if (!pud_present(*pud)) 2382 return; 2383 2384 pmd = pmd_offset(pud, address); 2385 2386 __split_huge_pmd(vma, pmd, address, freeze, page); 2387 } 2388 2389 void vma_adjust_trans_huge(struct vm_area_struct *vma, 2390 unsigned long start, 2391 unsigned long end, 2392 long adjust_next) 2393 { 2394 /* 2395 * If the new start address isn't hpage aligned and it could 2396 * previously contain an hugepage: check if we need to split 2397 * an huge pmd. 2398 */ 2399 if (start & ~HPAGE_PMD_MASK && 2400 (start & HPAGE_PMD_MASK) >= vma->vm_start && 2401 (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2402 split_huge_pmd_address(vma, start, false, NULL); 2403 2404 /* 2405 * If the new end address isn't hpage aligned and it could 2406 * previously contain an hugepage: check if we need to split 2407 * an huge pmd. 2408 */ 2409 if (end & ~HPAGE_PMD_MASK && 2410 (end & HPAGE_PMD_MASK) >= vma->vm_start && 2411 (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end) 2412 split_huge_pmd_address(vma, end, false, NULL); 2413 2414 /* 2415 * If we're also updating the vma->vm_next->vm_start, if the new 2416 * vm_next->vm_start isn't page aligned and it could previously 2417 * contain an hugepage: check if we need to split an huge pmd. 2418 */ 2419 if (adjust_next > 0) { 2420 struct vm_area_struct *next = vma->vm_next; 2421 unsigned long nstart = next->vm_start; 2422 nstart += adjust_next << PAGE_SHIFT; 2423 if (nstart & ~HPAGE_PMD_MASK && 2424 (nstart & HPAGE_PMD_MASK) >= next->vm_start && 2425 (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end) 2426 split_huge_pmd_address(next, nstart, false, NULL); 2427 } 2428 } 2429 2430 static void unmap_page(struct page *page) 2431 { 2432 enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS | 2433 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD; 2434 bool unmap_success; 2435 2436 VM_BUG_ON_PAGE(!PageHead(page), page); 2437 2438 if (PageAnon(page)) 2439 ttu_flags |= TTU_SPLIT_FREEZE; 2440 2441 unmap_success = try_to_unmap(page, ttu_flags); 2442 VM_BUG_ON_PAGE(!unmap_success, page); 2443 } 2444 2445 static void remap_page(struct page *page) 2446 { 2447 int i; 2448 if (PageTransHuge(page)) { 2449 remove_migration_ptes(page, page, true); 2450 } else { 2451 for (i = 0; i < HPAGE_PMD_NR; i++) 2452 remove_migration_ptes(page + i, page + i, true); 2453 } 2454 } 2455 2456 static void __split_huge_page_tail(struct page *head, int tail, 2457 struct lruvec *lruvec, struct list_head *list) 2458 { 2459 struct page *page_tail = head + tail; 2460 2461 VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail); 2462 2463 /* 2464 * Clone page flags before unfreezing refcount. 2465 * 2466 * After successful get_page_unless_zero() might follow flags change, 2467 * for exmaple lock_page() which set PG_waiters. 2468 */ 2469 page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; 2470 page_tail->flags |= (head->flags & 2471 ((1L << PG_referenced) | 2472 (1L << PG_swapbacked) | 2473 (1L << PG_swapcache) | 2474 (1L << PG_mlocked) | 2475 (1L << PG_uptodate) | 2476 (1L << PG_active) | 2477 (1L << PG_workingset) | 2478 (1L << PG_locked) | 2479 (1L << PG_unevictable) | 2480 (1L << PG_dirty))); 2481 2482 /* ->mapping in first tail page is compound_mapcount */ 2483 VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING, 2484 page_tail); 2485 page_tail->mapping = head->mapping; 2486 page_tail->index = head->index + tail; 2487 2488 /* Page flags must be visible before we make the page non-compound. */ 2489 smp_wmb(); 2490 2491 /* 2492 * Clear PageTail before unfreezing page refcount. 2493 * 2494 * After successful get_page_unless_zero() might follow put_page() 2495 * which needs correct compound_head(). 2496 */ 2497 clear_compound_head(page_tail); 2498 2499 /* Finally unfreeze refcount. Additional reference from page cache. */ 2500 page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) || 2501 PageSwapCache(head))); 2502 2503 if (page_is_young(head)) 2504 set_page_young(page_tail); 2505 if (page_is_idle(head)) 2506 set_page_idle(page_tail); 2507 2508 page_cpupid_xchg_last(page_tail, page_cpupid_last(head)); 2509 2510 /* 2511 * always add to the tail because some iterators expect new 2512 * pages to show after the currently processed elements - e.g. 2513 * migrate_pages 2514 */ 2515 lru_add_page_tail(head, page_tail, lruvec, list); 2516 } 2517 2518 static void __split_huge_page(struct page *page, struct list_head *list, 2519 pgoff_t end, unsigned long flags) 2520 { 2521 struct page *head = compound_head(page); 2522 pg_data_t *pgdat = page_pgdat(head); 2523 struct lruvec *lruvec; 2524 struct address_space *swap_cache = NULL; 2525 unsigned long offset = 0; 2526 int i; 2527 2528 lruvec = mem_cgroup_page_lruvec(head, pgdat); 2529 2530 /* complete memcg works before add pages to LRU */ 2531 mem_cgroup_split_huge_fixup(head); 2532 2533 if (PageAnon(head) && PageSwapCache(head)) { 2534 swp_entry_t entry = { .val = page_private(head) }; 2535 2536 offset = swp_offset(entry); 2537 swap_cache = swap_address_space(entry); 2538 xa_lock(&swap_cache->i_pages); 2539 } 2540 2541 for (i = HPAGE_PMD_NR - 1; i >= 1; i--) { 2542 __split_huge_page_tail(head, i, lruvec, list); 2543 /* Some pages can be beyond i_size: drop them from page cache */ 2544 if (head[i].index >= end) { 2545 ClearPageDirty(head + i); 2546 __delete_from_page_cache(head + i, NULL); 2547 if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head)) 2548 shmem_uncharge(head->mapping->host, 1); 2549 put_page(head + i); 2550 } else if (!PageAnon(page)) { 2551 __xa_store(&head->mapping->i_pages, head[i].index, 2552 head + i, 0); 2553 } else if (swap_cache) { 2554 __xa_store(&swap_cache->i_pages, offset + i, 2555 head + i, 0); 2556 } 2557 } 2558 2559 ClearPageCompound(head); 2560 2561 split_page_owner(head, HPAGE_PMD_ORDER); 2562 2563 /* See comment in __split_huge_page_tail() */ 2564 if (PageAnon(head)) { 2565 /* Additional pin to swap cache */ 2566 if (PageSwapCache(head)) { 2567 page_ref_add(head, 2); 2568 xa_unlock(&swap_cache->i_pages); 2569 } else { 2570 page_ref_inc(head); 2571 } 2572 } else { 2573 /* Additional pin to page cache */ 2574 page_ref_add(head, 2); 2575 xa_unlock(&head->mapping->i_pages); 2576 } 2577 2578 spin_unlock_irqrestore(&pgdat->lru_lock, flags); 2579 2580 remap_page(head); 2581 2582 for (i = 0; i < HPAGE_PMD_NR; i++) { 2583 struct page *subpage = head + i; 2584 if (subpage == page) 2585 continue; 2586 unlock_page(subpage); 2587 2588 /* 2589 * Subpages may be freed if there wasn't any mapping 2590 * like if add_to_swap() is running on a lru page that 2591 * had its mapping zapped. And freeing these pages 2592 * requires taking the lru_lock so we do the put_page 2593 * of the tail pages after the split is complete. 2594 */ 2595 put_page(subpage); 2596 } 2597 } 2598 2599 int total_mapcount(struct page *page) 2600 { 2601 int i, compound, ret; 2602 2603 VM_BUG_ON_PAGE(PageTail(page), page); 2604 2605 if (likely(!PageCompound(page))) 2606 return atomic_read(&page->_mapcount) + 1; 2607 2608 compound = compound_mapcount(page); 2609 if (PageHuge(page)) 2610 return compound; 2611 ret = compound; 2612 for (i = 0; i < HPAGE_PMD_NR; i++) 2613 ret += atomic_read(&page[i]._mapcount) + 1; 2614 /* File pages has compound_mapcount included in _mapcount */ 2615 if (!PageAnon(page)) 2616 return ret - compound * HPAGE_PMD_NR; 2617 if (PageDoubleMap(page)) 2618 ret -= HPAGE_PMD_NR; 2619 return ret; 2620 } 2621 2622 /* 2623 * This calculates accurately how many mappings a transparent hugepage 2624 * has (unlike page_mapcount() which isn't fully accurate). This full 2625 * accuracy is primarily needed to know if copy-on-write faults can 2626 * reuse the page and change the mapping to read-write instead of 2627 * copying them. At the same time this returns the total_mapcount too. 2628 * 2629 * The function returns the highest mapcount any one of the subpages 2630 * has. If the return value is one, even if different processes are 2631 * mapping different subpages of the transparent hugepage, they can 2632 * all reuse it, because each process is reusing a different subpage. 2633 * 2634 * The total_mapcount is instead counting all virtual mappings of the 2635 * subpages. If the total_mapcount is equal to "one", it tells the 2636 * caller all mappings belong to the same "mm" and in turn the 2637 * anon_vma of the transparent hugepage can become the vma->anon_vma 2638 * local one as no other process may be mapping any of the subpages. 2639 * 2640 * It would be more accurate to replace page_mapcount() with 2641 * page_trans_huge_mapcount(), however we only use 2642 * page_trans_huge_mapcount() in the copy-on-write faults where we 2643 * need full accuracy to avoid breaking page pinning, because 2644 * page_trans_huge_mapcount() is slower than page_mapcount(). 2645 */ 2646 int page_trans_huge_mapcount(struct page *page, int *total_mapcount) 2647 { 2648 int i, ret, _total_mapcount, mapcount; 2649 2650 /* hugetlbfs shouldn't call it */ 2651 VM_BUG_ON_PAGE(PageHuge(page), page); 2652 2653 if (likely(!PageTransCompound(page))) { 2654 mapcount = atomic_read(&page->_mapcount) + 1; 2655 if (total_mapcount) 2656 *total_mapcount = mapcount; 2657 return mapcount; 2658 } 2659 2660 page = compound_head(page); 2661 2662 _total_mapcount = ret = 0; 2663 for (i = 0; i < HPAGE_PMD_NR; i++) { 2664 mapcount = atomic_read(&page[i]._mapcount) + 1; 2665 ret = max(ret, mapcount); 2666 _total_mapcount += mapcount; 2667 } 2668 if (PageDoubleMap(page)) { 2669 ret -= 1; 2670 _total_mapcount -= HPAGE_PMD_NR; 2671 } 2672 mapcount = compound_mapcount(page); 2673 ret += mapcount; 2674 _total_mapcount += mapcount; 2675 if (total_mapcount) 2676 *total_mapcount = _total_mapcount; 2677 return ret; 2678 } 2679 2680 /* Racy check whether the huge page can be split */ 2681 bool can_split_huge_page(struct page *page, int *pextra_pins) 2682 { 2683 int extra_pins; 2684 2685 /* Additional pins from page cache */ 2686 if (PageAnon(page)) 2687 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0; 2688 else 2689 extra_pins = HPAGE_PMD_NR; 2690 if (pextra_pins) 2691 *pextra_pins = extra_pins; 2692 return total_mapcount(page) == page_count(page) - extra_pins - 1; 2693 } 2694 2695 /* 2696 * This function splits huge page into normal pages. @page can point to any 2697 * subpage of huge page to split. Split doesn't change the position of @page. 2698 * 2699 * Only caller must hold pin on the @page, otherwise split fails with -EBUSY. 2700 * The huge page must be locked. 2701 * 2702 * If @list is null, tail pages will be added to LRU list, otherwise, to @list. 2703 * 2704 * Both head page and tail pages will inherit mapping, flags, and so on from 2705 * the hugepage. 2706 * 2707 * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if 2708 * they are not mapped. 2709 * 2710 * Returns 0 if the hugepage is split successfully. 2711 * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under 2712 * us. 2713 */ 2714 int split_huge_page_to_list(struct page *page, struct list_head *list) 2715 { 2716 struct page *head = compound_head(page); 2717 struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); 2718 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2719 struct anon_vma *anon_vma = NULL; 2720 struct address_space *mapping = NULL; 2721 int count, mapcount, extra_pins, ret; 2722 bool mlocked; 2723 unsigned long flags; 2724 pgoff_t end; 2725 2726 VM_BUG_ON_PAGE(is_huge_zero_page(page), page); 2727 VM_BUG_ON_PAGE(!PageLocked(page), page); 2728 VM_BUG_ON_PAGE(!PageCompound(page), page); 2729 2730 if (PageWriteback(page)) 2731 return -EBUSY; 2732 2733 if (PageAnon(head)) { 2734 /* 2735 * The caller does not necessarily hold an mmap_sem that would 2736 * prevent the anon_vma disappearing so we first we take a 2737 * reference to it and then lock the anon_vma for write. This 2738 * is similar to page_lock_anon_vma_read except the write lock 2739 * is taken to serialise against parallel split or collapse 2740 * operations. 2741 */ 2742 anon_vma = page_get_anon_vma(head); 2743 if (!anon_vma) { 2744 ret = -EBUSY; 2745 goto out; 2746 } 2747 end = -1; 2748 mapping = NULL; 2749 anon_vma_lock_write(anon_vma); 2750 } else { 2751 mapping = head->mapping; 2752 2753 /* Truncated ? */ 2754 if (!mapping) { 2755 ret = -EBUSY; 2756 goto out; 2757 } 2758 2759 anon_vma = NULL; 2760 i_mmap_lock_read(mapping); 2761 2762 /* 2763 *__split_huge_page() may need to trim off pages beyond EOF: 2764 * but on 32-bit, i_size_read() takes an irq-unsafe seqlock, 2765 * which cannot be nested inside the page tree lock. So note 2766 * end now: i_size itself may be changed at any moment, but 2767 * head page lock is good enough to serialize the trimming. 2768 */ 2769 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); 2770 } 2771 2772 /* 2773 * Racy check if we can split the page, before unmap_page() will 2774 * split PMDs 2775 */ 2776 if (!can_split_huge_page(head, &extra_pins)) { 2777 ret = -EBUSY; 2778 goto out_unlock; 2779 } 2780 2781 mlocked = PageMlocked(page); 2782 unmap_page(head); 2783 VM_BUG_ON_PAGE(compound_mapcount(head), head); 2784 2785 /* Make sure the page is not on per-CPU pagevec as it takes pin */ 2786 if (mlocked) 2787 lru_add_drain(); 2788 2789 /* prevent PageLRU to go away from under us, and freeze lru stats */ 2790 spin_lock_irqsave(&pgdata->lru_lock, flags); 2791 2792 if (mapping) { 2793 XA_STATE(xas, &mapping->i_pages, page_index(head)); 2794 2795 /* 2796 * Check if the head page is present in page cache. 2797 * We assume all tail are present too, if head is there. 2798 */ 2799 xa_lock(&mapping->i_pages); 2800 if (xas_load(&xas) != head) 2801 goto fail; 2802 } 2803 2804 /* Prevent deferred_split_scan() touching ->_refcount */ 2805 spin_lock(&ds_queue->split_queue_lock); 2806 count = page_count(head); 2807 mapcount = total_mapcount(head); 2808 if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) { 2809 if (!list_empty(page_deferred_list(head))) { 2810 ds_queue->split_queue_len--; 2811 list_del(page_deferred_list(head)); 2812 } 2813 if (mapping) { 2814 if (PageSwapBacked(page)) 2815 __dec_node_page_state(page, NR_SHMEM_THPS); 2816 else 2817 __dec_node_page_state(page, NR_FILE_THPS); 2818 } 2819 2820 spin_unlock(&ds_queue->split_queue_lock); 2821 __split_huge_page(page, list, end, flags); 2822 if (PageSwapCache(head)) { 2823 swp_entry_t entry = { .val = page_private(head) }; 2824 2825 ret = split_swap_cluster(entry); 2826 } else 2827 ret = 0; 2828 } else { 2829 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) { 2830 pr_alert("total_mapcount: %u, page_count(): %u\n", 2831 mapcount, count); 2832 if (PageTail(page)) 2833 dump_page(head, NULL); 2834 dump_page(page, "total_mapcount(head) > 0"); 2835 BUG(); 2836 } 2837 spin_unlock(&ds_queue->split_queue_lock); 2838 fail: if (mapping) 2839 xa_unlock(&mapping->i_pages); 2840 spin_unlock_irqrestore(&pgdata->lru_lock, flags); 2841 remap_page(head); 2842 ret = -EBUSY; 2843 } 2844 2845 out_unlock: 2846 if (anon_vma) { 2847 anon_vma_unlock_write(anon_vma); 2848 put_anon_vma(anon_vma); 2849 } 2850 if (mapping) 2851 i_mmap_unlock_read(mapping); 2852 out: 2853 count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED); 2854 return ret; 2855 } 2856 2857 void free_transhuge_page(struct page *page) 2858 { 2859 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2860 unsigned long flags; 2861 2862 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2863 if (!list_empty(page_deferred_list(page))) { 2864 ds_queue->split_queue_len--; 2865 list_del(page_deferred_list(page)); 2866 } 2867 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2868 free_compound_page(page); 2869 } 2870 2871 void deferred_split_huge_page(struct page *page) 2872 { 2873 struct deferred_split *ds_queue = get_deferred_split_queue(page); 2874 #ifdef CONFIG_MEMCG 2875 struct mem_cgroup *memcg = compound_head(page)->mem_cgroup; 2876 #endif 2877 unsigned long flags; 2878 2879 VM_BUG_ON_PAGE(!PageTransHuge(page), page); 2880 2881 /* 2882 * The try_to_unmap() in page reclaim path might reach here too, 2883 * this may cause a race condition to corrupt deferred split queue. 2884 * And, if page reclaim is already handling the same page, it is 2885 * unnecessary to handle it again in shrinker. 2886 * 2887 * Check PageSwapCache to determine if the page is being 2888 * handled by page reclaim since THP swap would add the page into 2889 * swap cache before calling try_to_unmap(). 2890 */ 2891 if (PageSwapCache(page)) 2892 return; 2893 2894 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2895 if (list_empty(page_deferred_list(page))) { 2896 count_vm_event(THP_DEFERRED_SPLIT_PAGE); 2897 list_add_tail(page_deferred_list(page), &ds_queue->split_queue); 2898 ds_queue->split_queue_len++; 2899 #ifdef CONFIG_MEMCG 2900 if (memcg) 2901 memcg_set_shrinker_bit(memcg, page_to_nid(page), 2902 deferred_split_shrinker.id); 2903 #endif 2904 } 2905 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2906 } 2907 2908 static unsigned long deferred_split_count(struct shrinker *shrink, 2909 struct shrink_control *sc) 2910 { 2911 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2912 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2913 2914 #ifdef CONFIG_MEMCG 2915 if (sc->memcg) 2916 ds_queue = &sc->memcg->deferred_split_queue; 2917 #endif 2918 return READ_ONCE(ds_queue->split_queue_len); 2919 } 2920 2921 static unsigned long deferred_split_scan(struct shrinker *shrink, 2922 struct shrink_control *sc) 2923 { 2924 struct pglist_data *pgdata = NODE_DATA(sc->nid); 2925 struct deferred_split *ds_queue = &pgdata->deferred_split_queue; 2926 unsigned long flags; 2927 LIST_HEAD(list), *pos, *next; 2928 struct page *page; 2929 int split = 0; 2930 2931 #ifdef CONFIG_MEMCG 2932 if (sc->memcg) 2933 ds_queue = &sc->memcg->deferred_split_queue; 2934 #endif 2935 2936 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2937 /* Take pin on all head pages to avoid freeing them under us */ 2938 list_for_each_safe(pos, next, &ds_queue->split_queue) { 2939 page = list_entry((void *)pos, struct page, mapping); 2940 page = compound_head(page); 2941 if (get_page_unless_zero(page)) { 2942 list_move(page_deferred_list(page), &list); 2943 } else { 2944 /* We lost race with put_compound_page() */ 2945 list_del_init(page_deferred_list(page)); 2946 ds_queue->split_queue_len--; 2947 } 2948 if (!--sc->nr_to_scan) 2949 break; 2950 } 2951 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2952 2953 list_for_each_safe(pos, next, &list) { 2954 page = list_entry((void *)pos, struct page, mapping); 2955 if (!trylock_page(page)) 2956 goto next; 2957 /* split_huge_page() removes page from list on success */ 2958 if (!split_huge_page(page)) 2959 split++; 2960 unlock_page(page); 2961 next: 2962 put_page(page); 2963 } 2964 2965 spin_lock_irqsave(&ds_queue->split_queue_lock, flags); 2966 list_splice_tail(&list, &ds_queue->split_queue); 2967 spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); 2968 2969 /* 2970 * Stop shrinker if we didn't split any page, but the queue is empty. 2971 * This can happen if pages were freed under us. 2972 */ 2973 if (!split && list_empty(&ds_queue->split_queue)) 2974 return SHRINK_STOP; 2975 return split; 2976 } 2977 2978 static struct shrinker deferred_split_shrinker = { 2979 .count_objects = deferred_split_count, 2980 .scan_objects = deferred_split_scan, 2981 .seeks = DEFAULT_SEEKS, 2982 .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | 2983 SHRINKER_NONSLAB, 2984 }; 2985 2986 #ifdef CONFIG_DEBUG_FS 2987 static int split_huge_pages_set(void *data, u64 val) 2988 { 2989 struct zone *zone; 2990 struct page *page; 2991 unsigned long pfn, max_zone_pfn; 2992 unsigned long total = 0, split = 0; 2993 2994 if (val != 1) 2995 return -EINVAL; 2996 2997 for_each_populated_zone(zone) { 2998 max_zone_pfn = zone_end_pfn(zone); 2999 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) { 3000 if (!pfn_valid(pfn)) 3001 continue; 3002 3003 page = pfn_to_page(pfn); 3004 if (!get_page_unless_zero(page)) 3005 continue; 3006 3007 if (zone != page_zone(page)) 3008 goto next; 3009 3010 if (!PageHead(page) || PageHuge(page) || !PageLRU(page)) 3011 goto next; 3012 3013 total++; 3014 lock_page(page); 3015 if (!split_huge_page(page)) 3016 split++; 3017 unlock_page(page); 3018 next: 3019 put_page(page); 3020 } 3021 } 3022 3023 pr_info("%lu of %lu THP split\n", split, total); 3024 3025 return 0; 3026 } 3027 DEFINE_DEBUGFS_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set, 3028 "%llu\n"); 3029 3030 static int __init split_huge_pages_debugfs(void) 3031 { 3032 debugfs_create_file("split_huge_pages", 0200, NULL, NULL, 3033 &split_huge_pages_fops); 3034 return 0; 3035 } 3036 late_initcall(split_huge_pages_debugfs); 3037 #endif 3038 3039 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION 3040 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, 3041 struct page *page) 3042 { 3043 struct vm_area_struct *vma = pvmw->vma; 3044 struct mm_struct *mm = vma->vm_mm; 3045 unsigned long address = pvmw->address; 3046 pmd_t pmdval; 3047 swp_entry_t entry; 3048 pmd_t pmdswp; 3049 3050 if (!(pvmw->pmd && !pvmw->pte)) 3051 return; 3052 3053 flush_cache_range(vma, address, address + HPAGE_PMD_SIZE); 3054 pmdval = *pvmw->pmd; 3055 pmdp_invalidate(vma, address, pvmw->pmd); 3056 if (pmd_dirty(pmdval)) 3057 set_page_dirty(page); 3058 entry = make_migration_entry(page, pmd_write(pmdval)); 3059 pmdswp = swp_entry_to_pmd(entry); 3060 if (pmd_soft_dirty(pmdval)) 3061 pmdswp = pmd_swp_mksoft_dirty(pmdswp); 3062 set_pmd_at(mm, address, pvmw->pmd, pmdswp); 3063 page_remove_rmap(page, true); 3064 put_page(page); 3065 } 3066 3067 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) 3068 { 3069 struct vm_area_struct *vma = pvmw->vma; 3070 struct mm_struct *mm = vma->vm_mm; 3071 unsigned long address = pvmw->address; 3072 unsigned long mmun_start = address & HPAGE_PMD_MASK; 3073 pmd_t pmde; 3074 swp_entry_t entry; 3075 3076 if (!(pvmw->pmd && !pvmw->pte)) 3077 return; 3078 3079 entry = pmd_to_swp_entry(*pvmw->pmd); 3080 get_page(new); 3081 pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot)); 3082 if (pmd_swp_soft_dirty(*pvmw->pmd)) 3083 pmde = pmd_mksoft_dirty(pmde); 3084 if (is_write_migration_entry(entry)) 3085 pmde = maybe_pmd_mkwrite(pmde, vma); 3086 3087 flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE); 3088 if (PageAnon(new)) 3089 page_add_anon_rmap(new, vma, mmun_start, true); 3090 else 3091 page_add_file_rmap(new, true); 3092 set_pmd_at(mm, mmun_start, pvmw->pmd, pmde); 3093 if ((vma->vm_flags & VM_LOCKED) && !PageDoubleMap(new)) 3094 mlock_vma_page(new); 3095 update_mmu_cache_pmd(vma, address, pvmw->pmd); 3096 } 3097 #endif 3098