mm/huge_memory.c

   1 /*
   2  *  Copyright (C) 2009  Red Hat, Inc.
   3  *
   4  *  This work is licensed under the terms of the GNU GPL, version 2. See
   5  *  the COPYING file in the top-level directory.
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/mm.h>
  11 #include <linux/sched.h>
  12 #include <linux/sched/coredump.h>
  13 #include <linux/sched/numa_balancing.h>
  14 #include <linux/highmem.h>
  15 #include <linux/hugetlb.h>
  16 #include <linux/mmu_notifier.h>
  17 #include <linux/rmap.h>
  18 #include <linux/swap.h>
  19 #include <linux/shrinker.h>
  20 #include <linux/mm_inline.h>
  21 #include <linux/swapops.h>
  22 #include <linux/dax.h>
  23 #include <linux/khugepaged.h>
  24 #include <linux/freezer.h>
  25 #include <linux/pfn_t.h>
  26 #include <linux/mman.h>
  27 #include <linux/memremap.h>
  28 #include <linux/pagemap.h>
  29 #include <linux/debugfs.h>
  30 #include <linux/migrate.h>
  31 #include <linux/hashtable.h>
  32 #include <linux/userfaultfd_k.h>
  33 #include <linux/page_idle.h>
  34 #include <linux/shmem_fs.h>
  35 #include <linux/oom.h>
  36
  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 that avoid
  43  * to risk increase the memory footprint of applications without a guaranteed
  44  * benefit. When transparent hugepage support is enabled, is for all mappings,
  45  * 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 static struct page *get_huge_zero_page(void)
  66 {
  67         struct page *zero_page;
  68 retry:
  69         if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
  70                 return READ_ONCE(huge_zero_page);
  71
  72         zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
  73                         HPAGE_PMD_ORDER);
  74         if (!zero_page) {
  75                 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
  76                 return NULL;
  77         }
  78         count_vm_event(THP_ZERO_PAGE_ALLOC);
  79         preempt_disable();
  80         if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
  81                 preempt_enable();
  82                 __free_pages(zero_page, compound_order(zero_page));
  83                 goto retry;
  84         }
  85
  86         /* We take additional reference here. It will be put back by shrinker */
  87         atomic_set(&huge_zero_refcount, 2);
  88         preempt_enable();
  89         return READ_ONCE(huge_zero_page);
  90 }
  91
  92 static void put_huge_zero_page(void)
  93 {
  94         /*
  95          * Counter should never go to zero here. Only shrinker can put
  96          * last reference.
  97          */
  98         BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
  99 }
 100
 101 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
 102 {
 103         if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
 104                 return READ_ONCE(huge_zero_page);
 105
 106         if (!get_huge_zero_page())
 107                 return NULL;
 108
 109         if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
 110                 put_huge_zero_page();
 111
 112         return READ_ONCE(huge_zero_page);
 113 }
 114
 115 void mm_put_huge_zero_page(struct mm_struct *mm)
 116 {
 117         if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
 118                 put_huge_zero_page();
 119 }
 120
 121 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
 122                                         struct shrink_control *sc)
 123 {
 124         /* we can free zero page only if last reference remains */
 125         return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
 126 }
 127
 128 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
 129                                        struct shrink_control *sc)
 130 {
 131         if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
 132                 struct page *zero_page = xchg(&huge_zero_page, NULL);
 133                 BUG_ON(zero_page == NULL);
 134                 __free_pages(zero_page, compound_order(zero_page));
 135                 return HPAGE_PMD_NR;
 136         }
 137
 138         return 0;
 139 }
 140
 141 static struct shrinker huge_zero_page_shrinker = {
 142         .count_objects = shrink_huge_zero_page_count,
 143         .scan_objects = shrink_huge_zero_page_scan,
 144         .seeks = DEFAULT_SEEKS,
 145 };
 146
 147 #ifdef CONFIG_SYSFS
 148 static ssize_t enabled_show(struct kobject *kobj,
 149                             struct kobj_attribute *attr, char *buf)
 150 {
 151         if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
 152                 return sprintf(buf, "[always] madvise never\n");
 153         else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags))
 154                 return sprintf(buf, "always [madvise] never\n");
 155         else
 156                 return sprintf(buf, "always madvise [never]\n");
 157 }
 158
 159 static ssize_t enabled_store(struct kobject *kobj,
 160                              struct kobj_attribute *attr,
 161                              const char *buf, size_t count)
 162 {
 163         ssize_t ret = count;
 164
 165         if (!memcmp("always", buf,
 166                     min(sizeof("always")-1, count))) {
 167                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
 168                 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
 169         } else if (!memcmp("madvise", buf,
 170                            min(sizeof("madvise")-1, count))) {
 171                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
 172                 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
 173         } else if (!memcmp("never", buf,
 174                            min(sizeof("never")-1, count))) {
 175                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
 176                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
 177         } else
 178                 ret = -EINVAL;
 179
 180         if (ret > 0) {
 181                 int err = start_stop_khugepaged();
 182                 if (err)
 183                         ret = err;
 184         }
 185         return ret;
 186 }
 187 static struct kobj_attribute enabled_attr =
 188         __ATTR(enabled, 0644, enabled_show, enabled_store);
 189
 190 ssize_t single_hugepage_flag_show(struct kobject *kobj,
 191                                 struct kobj_attribute *attr, char *buf,
 192                                 enum transparent_hugepage_flag flag)
 193 {
 194         return sprintf(buf, "%d\n",
 195                        !!test_bit(flag, &transparent_hugepage_flags));
 196 }
 197
 198 ssize_t single_hugepage_flag_store(struct kobject *kobj,
 199                                  struct kobj_attribute *attr,
 200                                  const char *buf, size_t count,
 201                                  enum transparent_hugepage_flag flag)
 202 {
 203         unsigned long value;
 204         int ret;
 205
 206         ret = kstrtoul(buf, 10, &value);
 207         if (ret < 0)
 208                 return ret;
 209         if (value > 1)
 210                 return -EINVAL;
 211
 212         if (value)
 213                 set_bit(flag, &transparent_hugepage_flags);
 214         else
 215                 clear_bit(flag, &transparent_hugepage_flags);
 216
 217         return count;
 218 }
 219
 220 static ssize_t defrag_show(struct kobject *kobj,
 221                            struct kobj_attribute *attr, char *buf)
 222 {
 223         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
 224                 return sprintf(buf, "[always] defer defer+madvise madvise never\n");
 225         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
 226                 return sprintf(buf, "always [defer] defer+madvise madvise never\n");
 227         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
 228                 return sprintf(buf, "always defer [defer+madvise] madvise never\n");
 229         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
 230                 return sprintf(buf, "always defer defer+madvise [madvise] never\n");
 231         return sprintf(buf, "always defer defer+madvise madvise [never]\n");
 232 }
 233
 234 static ssize_t defrag_store(struct kobject *kobj,
 235                             struct kobj_attribute *attr,
 236                             const char *buf, size_t count)
 237 {
 238         if (!memcmp("always", buf,
 239                     min(sizeof("always")-1, count))) {
 240                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 241                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 242                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 243                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 244         } else if (!memcmp("defer+madvise", buf,
 245                     min(sizeof("defer+madvise")-1, count))) {
 246                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 247                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 248                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 249                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 250         } else if (!memcmp("defer", buf,
 251                     min(sizeof("defer")-1, count))) {
 252                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 253                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 254                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 255                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 256         } else if (!memcmp("madvise", buf,
 257                            min(sizeof("madvise")-1, count))) {
 258                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 259                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 260                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 261                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 262         } else if (!memcmp("never", buf,
 263                            min(sizeof("never")-1, count))) {
 264                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 265                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 266                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 267                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 268         } else
 269                 return -EINVAL;
 270
 271         return count;
 272 }
 273 static struct kobj_attribute defrag_attr =
 274         __ATTR(defrag, 0644, defrag_show, defrag_store);
 275
 276 static ssize_t use_zero_page_show(struct kobject *kobj,
 277                 struct kobj_attribute *attr, char *buf)
 278 {
 279         return single_hugepage_flag_show(kobj, attr, buf,
 280                                 TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
 281 }
 282 static ssize_t use_zero_page_store(struct kobject *kobj,
 283                 struct kobj_attribute *attr, const char *buf, size_t count)
 284 {
 285         return single_hugepage_flag_store(kobj, attr, buf, count,
 286                                  TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
 287 }
 288 static struct kobj_attribute use_zero_page_attr =
 289         __ATTR(use_zero_page, 0644, use_zero_page_show, use_zero_page_store);
 290
 291 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
 292                 struct kobj_attribute *attr, char *buf)
 293 {
 294         return sprintf(buf, "%lu\n", HPAGE_PMD_SIZE);
 295 }
 296 static struct kobj_attribute hpage_pmd_size_attr =
 297         __ATTR_RO(hpage_pmd_size);
 298
 299 #ifdef CONFIG_DEBUG_VM
 300 static ssize_t debug_cow_show(struct kobject *kobj,
 301                                 struct kobj_attribute *attr, char *buf)
 302 {
 303         return single_hugepage_flag_show(kobj, attr, buf,
 304                                 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
 305 }
 306 static ssize_t debug_cow_store(struct kobject *kobj,
 307                                struct kobj_attribute *attr,
 308                                const char *buf, size_t count)
 309 {
 310         return single_hugepage_flag_store(kobj, attr, buf, count,
 311                                  TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
 312 }
 313 static struct kobj_attribute debug_cow_attr =
 314         __ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
 315 #endif /* CONFIG_DEBUG_VM */
 316
 317 static struct attribute *hugepage_attr[] = {
 318         &enabled_attr.attr,
 319         &defrag_attr.attr,
 320         &use_zero_page_attr.attr,
 321         &hpage_pmd_size_attr.attr,
 322 #if defined(CONFIG_SHMEM) && defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE)
 323         &shmem_enabled_attr.attr,
 324 #endif
 325 #ifdef CONFIG_DEBUG_VM
 326         &debug_cow_attr.attr,
 327 #endif
 328         NULL,
 329 };
 330
 331 static const struct attribute_group hugepage_attr_group = {
 332         .attrs = hugepage_attr,
 333 };
 334
 335 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
 336 {
 337         int err;
 338
 339         *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
 340         if (unlikely(!*hugepage_kobj)) {
 341                 pr_err("failed to create transparent hugepage kobject\n");
 342                 return -ENOMEM;
 343         }
 344
 345         err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
 346         if (err) {
 347                 pr_err("failed to register transparent hugepage group\n");
 348                 goto delete_obj;
 349         }
 350
 351         err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
 352         if (err) {
 353                 pr_err("failed to register transparent hugepage group\n");
 354                 goto remove_hp_group;
 355         }
 356
 357         return 0;
 358
 359 remove_hp_group:
 360         sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
 361 delete_obj:
 362         kobject_put(*hugepage_kobj);
 363         return err;
 364 }
 365
 366 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
 367 {
 368         sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
 369         sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
 370         kobject_put(hugepage_kobj);
 371 }
 372 #else
 373 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
 374 {
 375         return 0;
 376 }
 377
 378 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
 379 {
 380 }
 381 #endif /* CONFIG_SYSFS */
 382
 383 static int __init hugepage_init(void)
 384 {
 385         int err;
 386         struct kobject *hugepage_kobj;
 387
 388         if (!has_transparent_hugepage()) {
 389                 transparent_hugepage_flags = 0;
 390                 return -EINVAL;
 391         }
 392
 393         /*
 394          * hugepages can't be allocated by the buddy allocator
 395          */
 396         MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER >= MAX_ORDER);
 397         /*
 398          * we use page->mapping and page->index in second tail page
 399          * as list_head: assuming THP order >= 2
 400          */
 401         MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
 402
 403         err = hugepage_init_sysfs(&hugepage_kobj);
 404         if (err)
 405                 goto err_sysfs;
 406
 407         err = khugepaged_init();
 408         if (err)
 409                 goto err_slab;
 410
 411         err = register_shrinker(&huge_zero_page_shrinker);
 412         if (err)
 413                 goto err_hzp_shrinker;
 414         err = register_shrinker(&deferred_split_shrinker);
 415         if (err)
 416                 goto err_split_shrinker;
 417
 418         /*
 419          * By default disable transparent hugepages on smaller systems,
 420          * where the extra memory used could hurt more than TLB overhead
 421          * is likely to save.  The admin can still enable it through /sys.
 422          */
 423         if (totalram_pages < (512 << (20 - PAGE_SHIFT))) {
 424                 transparent_hugepage_flags = 0;
 425                 return 0;
 426         }
 427
 428         err = start_stop_khugepaged();
 429         if (err)
 430                 goto err_khugepaged;
 431
 432         return 0;
 433 err_khugepaged:
 434         unregister_shrinker(&deferred_split_shrinker);
 435 err_split_shrinker:
 436         unregister_shrinker(&huge_zero_page_shrinker);
 437 err_hzp_shrinker:
 438         khugepaged_destroy();
 439 err_slab:
 440         hugepage_exit_sysfs(hugepage_kobj);
 441 err_sysfs:
 442         return err;
 443 }
 444 subsys_initcall(hugepage_init);
 445
 446 static int __init setup_transparent_hugepage(char *str)
 447 {
 448         int ret = 0;
 449         if (!str)
 450                 goto out;
 451         if (!strcmp(str, "always")) {
 452                 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
 453                         &transparent_hugepage_flags);
 454                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
 455                           &transparent_hugepage_flags);
 456                 ret = 1;
 457         } else if (!strcmp(str, "madvise")) {
 458                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
 459                           &transparent_hugepage_flags);
 460                 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
 461                         &transparent_hugepage_flags);
 462                 ret = 1;
 463         } else if (!strcmp(str, "never")) {
 464                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
 465                           &transparent_hugepage_flags);
 466                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
 467                           &transparent_hugepage_flags);
 468                 ret = 1;
 469         }
 470 out:
 471         if (!ret)
 472                 pr_warn("transparent_hugepage= cannot parse, ignored\n");
 473         return ret;
 474 }
 475 __setup("transparent_hugepage=", setup_transparent_hugepage);
 476
 477 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
 478 {
 479         if (likely(vma->vm_flags & VM_WRITE))
 480                 pmd = pmd_mkwrite(pmd);
 481         return pmd;
 482 }
 483
 484 static inline struct list_head *page_deferred_list(struct page *page)
 485 {
 486         /*
 487          * ->lru in the tail pages is occupied by compound_head.
 488          * Let's use ->mapping + ->index in the second tail page as list_head.
 489          */
 490         return (struct list_head *)&page[2].mapping;
 491 }
 492
 493 void prep_transhuge_page(struct page *page)
 494 {
 495         /*
 496          * we use page->mapping and page->indexlru in second tail page
 497          * as list_head: assuming THP order >= 2
 498          */
 499
 500         INIT_LIST_HEAD(page_deferred_list(page));
 501         set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
 502 }
 503
 504 unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
 505                 loff_t off, unsigned long flags, unsigned long size)
 506 {
 507         unsigned long addr;
 508         loff_t off_end = off + len;
 509         loff_t off_align = round_up(off, size);
 510         unsigned long len_pad;
 511
 512         if (off_end <= off_align || (off_end - off_align) < size)
 513                 return 0;
 514
 515         len_pad = len + size;
 516         if (len_pad < len || (off + len_pad) < off)
 517                 return 0;
 518
 519         addr = current->mm->get_unmapped_area(filp, 0, len_pad,
 520                                               off >> PAGE_SHIFT, flags);
 521         if (IS_ERR_VALUE(addr))
 522                 return 0;
 523
 524         addr += (off - addr) & (size - 1);
 525         return addr;
 526 }
 527
 528 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
 529                 unsigned long len, unsigned long pgoff, unsigned long flags)
 530 {
 531         loff_t off = (loff_t)pgoff << PAGE_SHIFT;
 532
 533         if (addr)
 534                 goto out;
 535         if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
 536                 goto out;
 537
 538         addr = __thp_get_unmapped_area(filp, len, off, flags, PMD_SIZE);
 539         if (addr)
 540                 return addr;
 541
 542  out:
 543         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 544 }
 545 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
 546
 547 static int __do_huge_pmd_anonymous_page(struct vm_fault *vmf, struct page *page,
 548                 gfp_t gfp)
 549 {
 550         struct vm_area_struct *vma = vmf->vma;
 551         struct mem_cgroup *memcg;
 552         pgtable_t pgtable;
 553         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
 554         int ret = 0;
 555
 556         VM_BUG_ON_PAGE(!PageCompound(page), page);
 557
 558         if (mem_cgroup_try_charge(page, vma->vm_mm, gfp, &memcg, true)) {
 559                 put_page(page);
 560                 count_vm_event(THP_FAULT_FALLBACK);
 561                 return VM_FAULT_FALLBACK;
 562         }
 563
 564         pgtable = pte_alloc_one(vma->vm_mm, haddr);
 565         if (unlikely(!pgtable)) {
 566                 ret = VM_FAULT_OOM;
 567                 goto release;
 568         }
 569
 570         clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
 571         /*
 572          * The memory barrier inside __SetPageUptodate makes sure that
 573          * clear_huge_page writes become visible before the set_pmd_at()
 574          * write.
 575          */
 576         __SetPageUptodate(page);
 577
 578         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
 579         if (unlikely(!pmd_none(*vmf->pmd))) {
 580                 goto unlock_release;
 581         } else {
 582                 pmd_t entry;
 583
 584                 ret = check_stable_address_space(vma->vm_mm);
 585                 if (ret)
 586                         goto unlock_release;
 587
 588                 /* Deliver the page fault to userland */
 589                 if (userfaultfd_missing(vma)) {
 590                         int ret;
 591
 592                         spin_unlock(vmf->ptl);
 593                         mem_cgroup_cancel_charge(page, memcg, true);
 594                         put_page(page);
 595                         pte_free(vma->vm_mm, pgtable);
 596                         ret = handle_userfault(vmf, VM_UFFD_MISSING);
 597                         VM_BUG_ON(ret & VM_FAULT_FALLBACK);
 598                         return ret;
 599                 }
 600
 601                 entry = mk_huge_pmd(page, vma->vm_page_prot);
 602                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
 603                 page_add_new_anon_rmap(page, vma, haddr, true);
 604                 mem_cgroup_commit_charge(page, memcg, false, true);
 605                 lru_cache_add_active_or_unevictable(page, vma);
 606                 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
 607                 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
 608                 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
 609                 atomic_long_inc(&vma->vm_mm->nr_ptes);
 610                 spin_unlock(vmf->ptl);
 611                 count_vm_event(THP_FAULT_ALLOC);
 612         }
 613
 614         return 0;
 615 unlock_release:
 616         spin_unlock(vmf->ptl);
 617 release:
 618         if (pgtable)
 619                 pte_free(vma->vm_mm, pgtable);
 620         mem_cgroup_cancel_charge(page, memcg, true);
 621         put_page(page);
 622         return ret;
 623
 624 }
 625
 626 /*
 627  * always: directly stall for all thp allocations
 628  * defer: wake kswapd and fail if not immediately available
 629  * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
 630  *                fail if not immediately available
 631  * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
 632  *          available
 633  * never: never stall for any thp allocation
 634  */
 635 static inline gfp_t alloc_hugepage_direct_gfpmask(struct vm_area_struct *vma)
 636 {
 637         const bool vma_madvised = !!(vma->vm_flags & VM_HUGEPAGE);
 638
 639         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
 640                 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
 641         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
 642                 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
 643         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
 644                 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
 645                                                              __GFP_KSWAPD_RECLAIM);
 646         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
 647                 return GFP_TRANSHUGE_LIGHT | (vma_madvised ? __GFP_DIRECT_RECLAIM :
 648                                                              0);
 649         return GFP_TRANSHUGE_LIGHT;
 650 }
 651
 652 /* Caller must hold page table lock. */
 653 static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
 654                 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
 655                 struct page *zero_page)
 656 {
 657         pmd_t entry;
 658         if (!pmd_none(*pmd))
 659                 return false;
 660         entry = mk_pmd(zero_page, vma->vm_page_prot);
 661         entry = pmd_mkhuge(entry);
 662         if (pgtable)
 663                 pgtable_trans_huge_deposit(mm, pmd, pgtable);
 664         set_pmd_at(mm, haddr, pmd, entry);
 665         atomic_long_inc(&mm->nr_ptes);
 666         return true;
 667 }
 668
 669 int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 670 {
 671         struct vm_area_struct *vma = vmf->vma;
 672         gfp_t gfp;
 673         struct page *page;
 674         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
 675
 676         if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
 677                 return VM_FAULT_FALLBACK;
 678         if (unlikely(anon_vma_prepare(vma)))
 679                 return VM_FAULT_OOM;
 680         if (unlikely(khugepaged_enter(vma, vma->vm_flags)))
 681                 return VM_FAULT_OOM;
 682         if (!(vmf->flags & FAULT_FLAG_WRITE) &&
 683                         !mm_forbids_zeropage(vma->vm_mm) &&
 684                         transparent_hugepage_use_zero_page()) {
 685                 pgtable_t pgtable;
 686                 struct page *zero_page;
 687                 bool set;
 688                 int ret;
 689                 pgtable = pte_alloc_one(vma->vm_mm, haddr);
 690                 if (unlikely(!pgtable))
 691                         return VM_FAULT_OOM;
 692                 zero_page = mm_get_huge_zero_page(vma->vm_mm);
 693                 if (unlikely(!zero_page)) {
 694                         pte_free(vma->vm_mm, pgtable);
 695                         count_vm_event(THP_FAULT_FALLBACK);
 696                         return VM_FAULT_FALLBACK;
 697                 }
 698                 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
 699                 ret = 0;
 700                 set = false;
 701                 if (pmd_none(*vmf->pmd)) {
 702                         ret = check_stable_address_space(vma->vm_mm);
 703                         if (ret) {
 704                                 spin_unlock(vmf->ptl);
 705                         } else if (userfaultfd_missing(vma)) {
 706                                 spin_unlock(vmf->ptl);
 707                                 ret = handle_userfault(vmf, VM_UFFD_MISSING);
 708                                 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
 709                         } else {
 710                                 set_huge_zero_page(pgtable, vma->vm_mm, vma,
 711                                                    haddr, vmf->pmd, zero_page);
 712                                 spin_unlock(vmf->ptl);
 713                                 set = true;
 714                         }
 715                 } else
 716                         spin_unlock(vmf->ptl);
 717                 if (!set)
 718                         pte_free(vma->vm_mm, pgtable);
 719                 return ret;
 720         }
 721         gfp = alloc_hugepage_direct_gfpmask(vma);
 722         page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
 723         if (unlikely(!page)) {
 724                 count_vm_event(THP_FAULT_FALLBACK);
 725                 return VM_FAULT_FALLBACK;
 726         }
 727         prep_transhuge_page(page);
 728         return __do_huge_pmd_anonymous_page(vmf, page, gfp);
 729 }
 730
 731 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 732                 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
 733                 pgtable_t pgtable)
 734 {
 735         struct mm_struct *mm = vma->vm_mm;
 736         pmd_t entry;
 737         spinlock_t *ptl;
 738
 739         ptl = pmd_lock(mm, pmd);
 740         entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
 741         if (pfn_t_devmap(pfn))
 742                 entry = pmd_mkdevmap(entry);
 743         if (write) {
 744                 entry = pmd_mkyoung(pmd_mkdirty(entry));
 745                 entry = maybe_pmd_mkwrite(entry, vma);
 746         }
 747
 748         if (pgtable) {
 749                 pgtable_trans_huge_deposit(mm, pmd, pgtable);
 750                 atomic_long_inc(&mm->nr_ptes);
 751         }
 752
 753         set_pmd_at(mm, addr, pmd, entry);
 754         update_mmu_cache_pmd(vma, addr, pmd);
 755         spin_unlock(ptl);
 756 }
 757
 758 int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 759                         pmd_t *pmd, pfn_t pfn, bool write)
 760 {
 761         pgprot_t pgprot = vma->vm_page_prot;
 762         pgtable_t pgtable = NULL;
 763         /*
 764          * If we had pmd_special, we could avoid all these restrictions,
 765          * but we need to be consistent with PTEs and architectures that
 766          * can't support a 'special' bit.
 767          */
 768         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
 769         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
 770                                                 (VM_PFNMAP|VM_MIXEDMAP));
 771         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
 772         BUG_ON(!pfn_t_devmap(pfn));
 773
 774         if (addr < vma->vm_start || addr >= vma->vm_end)
 775                 return VM_FAULT_SIGBUS;
 776
 777         if (arch_needs_pgtable_deposit()) {
 778                 pgtable = pte_alloc_one(vma->vm_mm, addr);
 779                 if (!pgtable)
 780                         return VM_FAULT_OOM;
 781         }
 782
 783         track_pfn_insert(vma, &pgprot, pfn);
 784
 785         insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);
 786         return VM_FAULT_NOPAGE;
 787 }
 788 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
 789
 790 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 791 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
 792 {
 793         if (likely(vma->vm_flags & VM_WRITE))
 794                 pud = pud_mkwrite(pud);
 795         return pud;
 796 }
 797
 798 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
 799                 pud_t *pud, pfn_t pfn, pgprot_t prot, bool write)
 800 {
 801         struct mm_struct *mm = vma->vm_mm;
 802         pud_t entry;
 803         spinlock_t *ptl;
 804
 805         ptl = pud_lock(mm, pud);
 806         entry = pud_mkhuge(pfn_t_pud(pfn, prot));
 807         if (pfn_t_devmap(pfn))
 808                 entry = pud_mkdevmap(entry);
 809         if (write) {
 810                 entry = pud_mkyoung(pud_mkdirty(entry));
 811                 entry = maybe_pud_mkwrite(entry, vma);
 812         }
 813         set_pud_at(mm, addr, pud, entry);
 814         update_mmu_cache_pud(vma, addr, pud);
 815         spin_unlock(ptl);
 816 }
 817
 818 int vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
 819                         pud_t *pud, pfn_t pfn, bool write)
 820 {
 821         pgprot_t pgprot = vma->vm_page_prot;
 822         /*
 823          * If we had pud_special, we could avoid all these restrictions,
 824          * but we need to be consistent with PTEs and architectures that
 825          * can't support a 'special' bit.
 826          */
 827         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
 828         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
 829                                                 (VM_PFNMAP|VM_MIXEDMAP));
 830         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
 831         BUG_ON(!pfn_t_devmap(pfn));
 832
 833         if (addr < vma->vm_start || addr >= vma->vm_end)
 834                 return VM_FAULT_SIGBUS;
 835
 836         track_pfn_insert(vma, &pgprot, pfn);
 837
 838         insert_pfn_pud(vma, addr, pud, pfn, pgprot, write);
 839         return VM_FAULT_NOPAGE;
 840 }
 841 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
 842 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 843
 844 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
 845                 pmd_t *pmd)
 846 {
 847         pmd_t _pmd;
 848
 849         /*
 850          * We should set the dirty bit only for FOLL_WRITE but for now
 851          * the dirty bit in the pmd is meaningless.  And if the dirty
 852          * bit will become meaningful and we'll only set it with
 853          * FOLL_WRITE, an atomic set_bit will be required on the pmd to
 854          * set the young bit, instead of the current set_pmd_at.
 855          */
 856         _pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
 857         if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
 858                                 pmd, _pmd,  1))
 859                 update_mmu_cache_pmd(vma, addr, pmd);
 860 }
 861
 862 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
 863                 pmd_t *pmd, int flags)
 864 {
 865         unsigned long pfn = pmd_pfn(*pmd);
 866         struct mm_struct *mm = vma->vm_mm;
 867         struct dev_pagemap *pgmap;
 868         struct page *page;
 869
 870         assert_spin_locked(pmd_lockptr(mm, pmd));
 871
 872         /*
 873          * When we COW a devmap PMD entry, we split it into PTEs, so we should
 874          * not be in this function with `flags & FOLL_COW` set.
 875          */
 876         WARN_ONCE(flags & FOLL_COW, "mm: In follow_devmap_pmd with FOLL_COW set");
 877
 878         if (flags & FOLL_WRITE && !pmd_write(*pmd))
 879                 return NULL;
 880
 881         if (pmd_present(*pmd) && pmd_devmap(*pmd))
 882                 /* pass */;
 883         else
 884                 return NULL;
 885
 886         if (flags & FOLL_TOUCH)
 887                 touch_pmd(vma, addr, pmd);
 888
 889         /*
 890          * device mapped pages can only be returned if the
 891          * caller will manage the page reference count.
 892          */
 893         if (!(flags & FOLL_GET))
 894                 return ERR_PTR(-EEXIST);
 895
 896         pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
 897         pgmap = get_dev_pagemap(pfn, NULL);
 898         if (!pgmap)
 899                 return ERR_PTR(-EFAULT);
 900         page = pfn_to_page(pfn);
 901         get_page(page);
 902         put_dev_pagemap(pgmap);
 903
 904         return page;
 905 }
 906
 907 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 908                   pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
 909                   struct vm_area_struct *vma)
 910 {
 911         spinlock_t *dst_ptl, *src_ptl;
 912         struct page *src_page;
 913         pmd_t pmd;
 914         pgtable_t pgtable = NULL;
 915         int ret = -ENOMEM;
 916
 917         /* Skip if can be re-fill on fault */
 918         if (!vma_is_anonymous(vma))
 919                 return 0;
 920
 921         pgtable = pte_alloc_one(dst_mm, addr);
 922         if (unlikely(!pgtable))
 923                 goto out;
 924
 925         dst_ptl = pmd_lock(dst_mm, dst_pmd);
 926         src_ptl = pmd_lockptr(src_mm, src_pmd);
 927         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
 928
 929         ret = -EAGAIN;
 930         pmd = *src_pmd;
 931
 932 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
 933         if (unlikely(is_swap_pmd(pmd))) {
 934                 swp_entry_t entry = pmd_to_swp_entry(pmd);
 935
 936                 VM_BUG_ON(!is_pmd_migration_entry(pmd));
 937                 if (is_write_migration_entry(entry)) {
 938                         make_migration_entry_read(&entry);
 939                         pmd = swp_entry_to_pmd(entry);
 940                         if (pmd_swp_soft_dirty(*src_pmd))
 941                                 pmd = pmd_swp_mksoft_dirty(pmd);
 942                         set_pmd_at(src_mm, addr, src_pmd, pmd);
 943                 }
 944                 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
 945                 ret = 0;
 946                 goto out_unlock;
 947         }
 948 #endif
 949
 950         if (unlikely(!pmd_trans_huge(pmd))) {
 951                 pte_free(dst_mm, pgtable);
 952                 goto out_unlock;
 953         }
 954         /*
 955          * When page table lock is held, the huge zero pmd should not be
 956          * under splitting since we don't split the page itself, only pmd to
 957          * a page table.
 958          */
 959         if (is_huge_zero_pmd(pmd)) {
 960                 struct page *zero_page;
 961                 /*
 962                  * get_huge_zero_page() will never allocate a new page here,
 963                  * since we already have a zero page to copy. It just takes a
 964                  * reference.
 965                  */
 966                 zero_page = mm_get_huge_zero_page(dst_mm);
 967                 set_huge_zero_page(pgtable, dst_mm, vma, addr, dst_pmd,
 968                                 zero_page);
 969                 ret = 0;
 970                 goto out_unlock;
 971         }
 972
 973         src_page = pmd_page(pmd);
 974         VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
 975         get_page(src_page);
 976         page_dup_rmap(src_page, true);
 977         add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
 978         atomic_long_inc(&dst_mm->nr_ptes);
 979         pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
 980
 981         pmdp_set_wrprotect(src_mm, addr, src_pmd);
 982         pmd = pmd_mkold(pmd_wrprotect(pmd));
 983         set_pmd_at(dst_mm, addr, dst_pmd, pmd);
 984
 985         ret = 0;
 986 out_unlock:
 987         spin_unlock(src_ptl);
 988         spin_unlock(dst_ptl);
 989 out:
 990         return ret;
 991 }
 992
 993 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 994 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
 995                 pud_t *pud)
 996 {
 997         pud_t _pud;
 998
 999         /*
1000          * We should set the dirty bit only for FOLL_WRITE but for now
1001          * the dirty bit in the pud is meaningless.  And if the dirty
1002          * bit will become meaningful and we'll only set it with
1003          * FOLL_WRITE, an atomic set_bit will be required on the pud to
1004          * set the young bit, instead of the current set_pud_at.
1005          */
1006         _pud = pud_mkyoung(pud_mkdirty(*pud));
1007         if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1008                                 pud, _pud,  1))
1009                 update_mmu_cache_pud(vma, addr, pud);
1010 }
1011
1012 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1013                 pud_t *pud, int flags)
1014 {
1015         unsigned long pfn = pud_pfn(*pud);
1016         struct mm_struct *mm = vma->vm_mm;
1017         struct dev_pagemap *pgmap;
1018         struct page *page;
1019
1020         assert_spin_locked(pud_lockptr(mm, pud));
1021
1022         if (flags & FOLL_WRITE && !pud_write(*pud))
1023                 return NULL;
1024
1025         if (pud_present(*pud) && pud_devmap(*pud))
1026                 /* pass */;
1027         else
1028                 return NULL;
1029
1030         if (flags & FOLL_TOUCH)
1031                 touch_pud(vma, addr, pud);
1032
1033         /*
1034          * device mapped pages can only be returned if the
1035          * caller will manage the page reference count.
1036          */
1037         if (!(flags & FOLL_GET))
1038                 return ERR_PTR(-EEXIST);
1039
1040         pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1041         pgmap = get_dev_pagemap(pfn, NULL);
1042         if (!pgmap)
1043                 return ERR_PTR(-EFAULT);
1044         page = pfn_to_page(pfn);
1045         get_page(page);
1046         put_dev_pagemap(pgmap);
1047
1048         return page;
1049 }
1050
1051 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1052                   pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1053                   struct vm_area_struct *vma)
1054 {
1055         spinlock_t *dst_ptl, *src_ptl;
1056         pud_t pud;
1057         int ret;
1058
1059         dst_ptl = pud_lock(dst_mm, dst_pud);
1060         src_ptl = pud_lockptr(src_mm, src_pud);
1061         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1062
1063         ret = -EAGAIN;
1064         pud = *src_pud;
1065         if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1066                 goto out_unlock;
1067
1068         /*
1069          * When page table lock is held, the huge zero pud should not be
1070          * under splitting since we don't split the page itself, only pud to
1071          * a page table.
1072          */
1073         if (is_huge_zero_pud(pud)) {
1074                 /* No huge zero pud yet */
1075         }
1076
1077         pudp_set_wrprotect(src_mm, addr, src_pud);
1078         pud = pud_mkold(pud_wrprotect(pud));
1079         set_pud_at(dst_mm, addr, dst_pud, pud);
1080
1081         ret = 0;
1082 out_unlock:
1083         spin_unlock(src_ptl);
1084         spin_unlock(dst_ptl);
1085         return ret;
1086 }
1087
1088 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1089 {
1090         pud_t entry;
1091         unsigned long haddr;
1092         bool write = vmf->flags & FAULT_FLAG_WRITE;
1093
1094         vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1095         if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1096                 goto unlock;
1097
1098         entry = pud_mkyoung(orig_pud);
1099         if (write)
1100                 entry = pud_mkdirty(entry);
1101         haddr = vmf->address & HPAGE_PUD_MASK;
1102         if (pudp_set_access_flags(vmf->vma, haddr, vmf->pud, entry, write))
1103                 update_mmu_cache_pud(vmf->vma, vmf->address, vmf->pud);
1104
1105 unlock:
1106         spin_unlock(vmf->ptl);
1107 }
1108 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1109
1110 void huge_pmd_set_accessed(struct vm_fault *vmf, pmd_t orig_pmd)
1111 {
1112         pmd_t entry;
1113         unsigned long haddr;
1114         bool write = vmf->flags & FAULT_FLAG_WRITE;
1115
1116         vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1117         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1118                 goto unlock;
1119
1120         entry = pmd_mkyoung(orig_pmd);
1121         if (write)
1122                 entry = pmd_mkdirty(entry);
1123         haddr = vmf->address & HPAGE_PMD_MASK;
1124         if (pmdp_set_access_flags(vmf->vma, haddr, vmf->pmd, entry, write))
1125                 update_mmu_cache_pmd(vmf->vma, vmf->address, vmf->pmd);
1126
1127 unlock:
1128         spin_unlock(vmf->ptl);
1129 }
1130
1131 static int do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pmd_t orig_pmd,
1132                 struct page *page)
1133 {
1134         struct vm_area_struct *vma = vmf->vma;
1135         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1136         struct mem_cgroup *memcg;
1137         pgtable_t pgtable;
1138         pmd_t _pmd;
1139         int ret = 0, i;
1140         struct page **pages;
1141         unsigned long mmun_start;       /* For mmu_notifiers */
1142         unsigned long mmun_end;         /* For mmu_notifiers */
1143
1144         pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
1145                         GFP_KERNEL);
1146         if (unlikely(!pages)) {
1147                 ret |= VM_FAULT_OOM;
1148                 goto out;
1149         }
1150
1151         for (i = 0; i < HPAGE_PMD_NR; i++) {
1152                 pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE, vma,
1153                                                vmf->address, page_to_nid(page));
1154                 if (unlikely(!pages[i] ||
1155                              mem_cgroup_try_charge(pages[i], vma->vm_mm,
1156                                      GFP_KERNEL, &memcg, false))) {
1157                         if (pages[i])
1158                                 put_page(pages[i]);
1159                         while (--i >= 0) {
1160                                 memcg = (void *)page_private(pages[i]);
1161                                 set_page_private(pages[i], 0);
1162                                 mem_cgroup_cancel_charge(pages[i], memcg,
1163                                                 false);
1164                                 put_page(pages[i]);
1165                         }
1166                         kfree(pages);
1167                         ret |= VM_FAULT_OOM;
1168                         goto out;
1169                 }
1170                 set_page_private(pages[i], (unsigned long)memcg);
1171         }
1172
1173         for (i = 0; i < HPAGE_PMD_NR; i++) {
1174                 copy_user_highpage(pages[i], page + i,
1175                                    haddr + PAGE_SIZE * i, vma);
1176                 __SetPageUptodate(pages[i]);
1177                 cond_resched();
1178         }
1179
1180         mmun_start = haddr;
1181         mmun_end   = haddr + HPAGE_PMD_SIZE;
1182         mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1183
1184         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1185         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1186                 goto out_free_pages;
1187         VM_BUG_ON_PAGE(!PageHead(page), page);
1188
1189         pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1190         /* leave pmd empty until pte is filled */
1191
1192         pgtable = pgtable_trans_huge_withdraw(vma->vm_mm, vmf->pmd);
1193         pmd_populate(vma->vm_mm, &_pmd, pgtable);
1194
1195         for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
1196                 pte_t entry;
1197                 entry = mk_pte(pages[i], vma->vm_page_prot);
1198                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1199                 memcg = (void *)page_private(pages[i]);
1200                 set_page_private(pages[i], 0);
1201                 page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
1202                 mem_cgroup_commit_charge(pages[i], memcg, false, false);
1203                 lru_cache_add_active_or_unevictable(pages[i], vma);
1204                 vmf->pte = pte_offset_map(&_pmd, haddr);
1205                 VM_BUG_ON(!pte_none(*vmf->pte));
1206                 set_pte_at(vma->vm_mm, haddr, vmf->pte, entry);
1207                 pte_unmap(vmf->pte);
1208         }
1209         kfree(pages);
1210
1211         smp_wmb(); /* make pte visible before pmd */
1212         pmd_populate(vma->vm_mm, vmf->pmd, pgtable);
1213         page_remove_rmap(page, true);
1214         spin_unlock(vmf->ptl);
1215
1216         mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1217
1218         ret |= VM_FAULT_WRITE;
1219         put_page(page);
1220
1221 out:
1222         return ret;
1223
1224 out_free_pages:
1225         spin_unlock(vmf->ptl);
1226         mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1227         for (i = 0; i < HPAGE_PMD_NR; i++) {
1228                 memcg = (void *)page_private(pages[i]);
1229                 set_page_private(pages[i], 0);
1230                 mem_cgroup_cancel_charge(pages[i], memcg, false);
1231                 put_page(pages[i]);
1232         }
1233         kfree(pages);
1234         goto out;
1235 }
1236
1237 int do_huge_pmd_wp_page(struct vm_fault *vmf, pmd_t orig_pmd)
1238 {
1239         struct vm_area_struct *vma = vmf->vma;
1240         struct page *page = NULL, *new_page;
1241         struct mem_cgroup *memcg;
1242         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1243         unsigned long mmun_start;       /* For mmu_notifiers */
1244         unsigned long mmun_end;         /* For mmu_notifiers */
1245         gfp_t huge_gfp;                 /* for allocation and charge */
1246         int ret = 0;
1247
1248         vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1249         VM_BUG_ON_VMA(!vma->anon_vma, vma);
1250         if (is_huge_zero_pmd(orig_pmd))
1251                 goto alloc;
1252         spin_lock(vmf->ptl);
1253         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd)))
1254                 goto out_unlock;
1255
1256         page = pmd_page(orig_pmd);
1257         VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
1258         /*
1259          * We can only reuse the page if nobody else maps the huge page or it's
1260          * part.
1261          */
1262         if (!trylock_page(page)) {
1263                 get_page(page);
1264                 spin_unlock(vmf->ptl);
1265                 lock_page(page);
1266                 spin_lock(vmf->ptl);
1267                 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1268                         unlock_page(page);
1269                         put_page(page);
1270                         goto out_unlock;
1271                 }
1272                 put_page(page);
1273         }
1274         if (reuse_swap_page(page, NULL)) {
1275                 pmd_t entry;
1276                 entry = pmd_mkyoung(orig_pmd);
1277                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1278                 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry,  1))
1279                         update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1280                 ret |= VM_FAULT_WRITE;
1281                 unlock_page(page);
1282                 goto out_unlock;
1283         }
1284         unlock_page(page);
1285         get_page(page);
1286         spin_unlock(vmf->ptl);
1287 alloc:
1288         if (transparent_hugepage_enabled(vma) &&
1289             !transparent_hugepage_debug_cow()) {
1290                 huge_gfp = alloc_hugepage_direct_gfpmask(vma);
1291                 new_page = alloc_hugepage_vma(huge_gfp, vma, haddr, HPAGE_PMD_ORDER);
1292         } else
1293                 new_page = NULL;
1294
1295         if (likely(new_page)) {
1296                 prep_transhuge_page(new_page);
1297         } else {
1298                 if (!page) {
1299                         split_huge_pmd(vma, vmf->pmd, vmf->address);
1300                         ret |= VM_FAULT_FALLBACK;
1301                 } else {
1302                         ret = do_huge_pmd_wp_page_fallback(vmf, orig_pmd, page);
1303                         if (ret & VM_FAULT_OOM) {
1304                                 split_huge_pmd(vma, vmf->pmd, vmf->address);
1305                                 ret |= VM_FAULT_FALLBACK;
1306                         }
1307                         put_page(page);
1308                 }
1309                 count_vm_event(THP_FAULT_FALLBACK);
1310                 goto out;
1311         }
1312
1313         if (unlikely(mem_cgroup_try_charge(new_page, vma->vm_mm,
1314                                         huge_gfp, &memcg, true))) {
1315                 put_page(new_page);
1316                 split_huge_pmd(vma, vmf->pmd, vmf->address);
1317                 if (page)
1318                         put_page(page);
1319                 ret |= VM_FAULT_FALLBACK;
1320                 count_vm_event(THP_FAULT_FALLBACK);
1321                 goto out;
1322         }
1323
1324         count_vm_event(THP_FAULT_ALLOC);
1325
1326         if (!page)
1327                 clear_huge_page(new_page, vmf->address, HPAGE_PMD_NR);
1328         else
1329                 copy_user_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
1330         __SetPageUptodate(new_page);
1331
1332         mmun_start = haddr;
1333         mmun_end   = haddr + HPAGE_PMD_SIZE;
1334         mmu_notifier_invalidate_range_start(vma->vm_mm, mmun_start, mmun_end);
1335
1336         spin_lock(vmf->ptl);
1337         if (page)
1338                 put_page(page);
1339         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1340                 spin_unlock(vmf->ptl);
1341                 mem_cgroup_cancel_charge(new_page, memcg, true);
1342                 put_page(new_page);
1343                 goto out_mn;
1344         } else {
1345                 pmd_t entry;
1346                 entry = mk_huge_pmd(new_page, vma->vm_page_prot);
1347                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1348                 pmdp_huge_clear_flush_notify(vma, haddr, vmf->pmd);
1349                 page_add_new_anon_rmap(new_page, vma, haddr, true);
1350                 mem_cgroup_commit_charge(new_page, memcg, false, true);
1351                 lru_cache_add_active_or_unevictable(new_page, vma);
1352                 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
1353                 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1354                 if (!page) {
1355                         add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1356                 } else {
1357                         VM_BUG_ON_PAGE(!PageHead(page), page);
1358                         page_remove_rmap(page, true);
1359                         put_page(page);
1360                 }
1361                 ret |= VM_FAULT_WRITE;
1362         }
1363         spin_unlock(vmf->ptl);
1364 out_mn:
1365         mmu_notifier_invalidate_range_end(vma->vm_mm, mmun_start, mmun_end);
1366 out:
1367         return ret;
1368 out_unlock:
1369         spin_unlock(vmf->ptl);
1370         return ret;
1371 }
1372
1373 /*
1374  * FOLL_FORCE can write to even unwritable pmd's, but only
1375  * after we've gone through a COW cycle and they are dirty.
1376  */
1377 static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags)
1378 {
1379         return pmd_write(pmd) ||
1380                ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd));
1381 }
1382
1383 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1384                                    unsigned long addr,
1385                                    pmd_t *pmd,
1386                                    unsigned int flags)
1387 {
1388         struct mm_struct *mm = vma->vm_mm;
1389         struct page *page = NULL;
1390
1391         assert_spin_locked(pmd_lockptr(mm, pmd));
1392
1393         if (flags & FOLL_WRITE && !can_follow_write_pmd(*pmd, flags))
1394                 goto out;
1395
1396         /* Avoid dumping huge zero page */
1397         if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1398                 return ERR_PTR(-EFAULT);
1399
1400         /* Full NUMA hinting faults to serialise migration in fault paths */
1401         if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
1402                 goto out;
1403
1404         page = pmd_page(*pmd);
1405         VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1406         if (flags & FOLL_TOUCH)
1407                 touch_pmd(vma, addr, pmd);
1408         if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1409                 /*
1410                  * We don't mlock() pte-mapped THPs. This way we can avoid
1411                  * leaking mlocked pages into non-VM_LOCKED VMAs.
1412                  *
1413                  * For anon THP:
1414                  *
1415                  * In most cases the pmd is the only mapping of the page as we
1416                  * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for
1417                  * writable private mappings in populate_vma_page_range().
1418                  *
1419                  * The only scenario when we have the page shared here is if we
1420                  * mlocking read-only mapping shared over fork(). We skip
1421                  * mlocking such pages.
1422                  *
1423                  * For file THP:
1424                  *
1425                  * We can expect PageDoubleMap() to be stable under page lock:
1426                  * for file pages we set it in page_add_file_rmap(), which
1427                  * requires page to be locked.
1428                  */
1429
1430                 if (PageAnon(page) && compound_mapcount(page) != 1)
1431                         goto skip_mlock;
1432                 if (PageDoubleMap(page) || !page->mapping)
1433                         goto skip_mlock;
1434                 if (!trylock_page(page))
1435                         goto skip_mlock;
1436                 lru_add_drain();
1437                 if (page->mapping && !PageDoubleMap(page))
1438                         mlock_vma_page(page);
1439                 unlock_page(page);
1440         }
1441 skip_mlock:
1442         page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1443         VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1444         if (flags & FOLL_GET)
1445                 get_page(page);
1446
1447 out:
1448         return page;
1449 }
1450
1451 /* NUMA hinting page fault entry point for trans huge pmds */
1452 int do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd)
1453 {
1454         struct vm_area_struct *vma = vmf->vma;
1455         struct anon_vma *anon_vma = NULL;
1456         struct page *page;
1457         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1458         int page_nid = -1, this_nid = numa_node_id();
1459         int target_nid, last_cpupid = -1;
1460         bool page_locked;
1461         bool migrated = false;
1462         bool was_writable;
1463         int flags = 0;
1464
1465         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1466         if (unlikely(!pmd_same(pmd, *vmf->pmd)))
1467                 goto out_unlock;
1468
1469         /*
1470          * If there are potential migrations, wait for completion and retry
1471          * without disrupting NUMA hinting information. Do not relock and
1472          * check_same as the page may no longer be mapped.
1473          */
1474         if (unlikely(pmd_trans_migrating(*vmf->pmd))) {
1475                 page = pmd_page(*vmf->pmd);
1476                 if (!get_page_unless_zero(page))
1477                         goto out_unlock;
1478                 spin_unlock(vmf->ptl);
1479                 wait_on_page_locked(page);
1480                 put_page(page);
1481                 goto out;
1482         }
1483
1484         page = pmd_page(pmd);
1485         BUG_ON(is_huge_zero_page(page));
1486         page_nid = page_to_nid(page);
1487         last_cpupid = page_cpupid_last(page);
1488         count_vm_numa_event(NUMA_HINT_FAULTS);
1489         if (page_nid == this_nid) {
1490                 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
1491                 flags |= TNF_FAULT_LOCAL;
1492         }
1493
1494         /* See similar comment in do_numa_page for explanation */
1495         if (!pmd_savedwrite(pmd))
1496                 flags |= TNF_NO_GROUP;
1497
1498         /*
1499          * Acquire the page lock to serialise THP migrations but avoid dropping
1500          * page_table_lock if at all possible
1501          */
1502         page_locked = trylock_page(page);
1503         target_nid = mpol_misplaced(page, vma, haddr);
1504         if (target_nid == -1) {
1505                 /* If the page was locked, there are no parallel migrations */
1506                 if (page_locked)
1507                         goto clear_pmdnuma;
1508         }
1509
1510         /* Migration could have started since the pmd_trans_migrating check */
1511         if (!page_locked) {
1512                 page_nid = -1;
1513                 if (!get_page_unless_zero(page))
1514                         goto out_unlock;
1515                 spin_unlock(vmf->ptl);
1516                 wait_on_page_locked(page);
1517                 put_page(page);
1518                 goto out;
1519         }
1520
1521         /*
1522          * Page is misplaced. Page lock serialises migrations. Acquire anon_vma
1523          * to serialises splits
1524          */
1525         get_page(page);
1526         spin_unlock(vmf->ptl);
1527         anon_vma = page_lock_anon_vma_read(page);
1528
1529         /* Confirm the PMD did not change while page_table_lock was released */
1530         spin_lock(vmf->ptl);
1531         if (unlikely(!pmd_same(pmd, *vmf->pmd))) {
1532                 unlock_page(page);
1533                 put_page(page);
1534                 page_nid = -1;
1535                 goto out_unlock;
1536         }
1537
1538         /* Bail if we fail to protect against THP splits for any reason */
1539         if (unlikely(!anon_vma)) {
1540                 put_page(page);
1541                 page_nid = -1;
1542                 goto clear_pmdnuma;
1543         }
1544
1545         /*
1546          * Since we took the NUMA fault, we must have observed the !accessible
1547          * bit. Make sure all other CPUs agree with that, to avoid them
1548          * modifying the page we're about to migrate.
1549          *
1550          * Must be done under PTL such that we'll observe the relevant
1551          * inc_tlb_flush_pending().
1552          *
1553          * We are not sure a pending tlb flush here is for a huge page
1554          * mapping or not. Hence use the tlb range variant
1555          */
1556         if (mm_tlb_flush_pending(vma->vm_mm))
1557                 flush_tlb_range(vma, haddr, haddr + HPAGE_PMD_SIZE);
1558
1559         /*
1560          * Migrate the THP to the requested node, returns with page unlocked
1561          * and access rights restored.
1562          */
1563         spin_unlock(vmf->ptl);
1564
1565         migrated = migrate_misplaced_transhuge_page(vma->vm_mm, vma,
1566                                 vmf->pmd, pmd, vmf->address, page, target_nid);
1567         if (migrated) {
1568                 flags |= TNF_MIGRATED;
1569                 page_nid = target_nid;
1570         } else
1571                 flags |= TNF_MIGRATE_FAIL;
1572
1573         goto out;
1574 clear_pmdnuma:
1575         BUG_ON(!PageLocked(page));
1576         was_writable = pmd_savedwrite(pmd);
1577         pmd = pmd_modify(pmd, vma->vm_page_prot);
1578         pmd = pmd_mkyoung(pmd);
1579         if (was_writable)
1580                 pmd = pmd_mkwrite(pmd);
1581         set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1582         update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1583         unlock_page(page);
1584 out_unlock:
1585         spin_unlock(vmf->ptl);
1586
1587 out:
1588         if (anon_vma)
1589                 page_unlock_anon_vma_read(anon_vma);
1590
1591         if (page_nid != -1)
1592                 task_numa_fault(last_cpupid, page_nid, HPAGE_PMD_NR,
1593                                 flags);
1594
1595         return 0;
1596 }
1597
1598 /*
1599  * Return true if we do MADV_FREE successfully on entire pmd page.
1600  * Otherwise, return false.
1601  */
1602 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1603                 pmd_t *pmd, unsigned long addr, unsigned long next)
1604 {
1605         spinlock_t *ptl;
1606         pmd_t orig_pmd;
1607         struct page *page;
1608         struct mm_struct *mm = tlb->mm;
1609         bool ret = false;
1610
1611         tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1612
1613         ptl = pmd_trans_huge_lock(pmd, vma);
1614         if (!ptl)
1615                 goto out_unlocked;
1616
1617         orig_pmd = *pmd;
1618         if (is_huge_zero_pmd(orig_pmd))
1619                 goto out;
1620
1621         if (unlikely(!pmd_present(orig_pmd))) {
1622                 VM_BUG_ON(thp_migration_supported() &&
1623                                   !is_pmd_migration_entry(orig_pmd));
1624                 goto out;
1625         }
1626
1627         page = pmd_page(orig_pmd);
1628         /*
1629          * If other processes are mapping this page, we couldn't discard
1630          * the page unless they all do MADV_FREE so let's skip the page.
1631          */
1632         if (page_mapcount(page) != 1)
1633                 goto out;
1634
1635         if (!trylock_page(page))
1636                 goto out;
1637
1638         /*
1639          * If user want to discard part-pages of THP, split it so MADV_FREE
1640          * will deactivate only them.
1641          */
1642         if (next - addr != HPAGE_PMD_SIZE) {
1643                 get_page(page);
1644                 spin_unlock(ptl);
1645                 split_huge_page(page);
1646                 unlock_page(page);
1647                 put_page(page);
1648                 goto out_unlocked;
1649         }
1650
1651         if (PageDirty(page))
1652                 ClearPageDirty(page);
1653         unlock_page(page);
1654
1655         if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1656                 pmdp_invalidate(vma, addr, pmd);
1657                 orig_pmd = pmd_mkold(orig_pmd);
1658                 orig_pmd = pmd_mkclean(orig_pmd);
1659
1660                 set_pmd_at(mm, addr, pmd, orig_pmd);
1661                 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1662         }
1663
1664         mark_page_lazyfree(page);
1665         ret = true;
1666 out:
1667         spin_unlock(ptl);
1668 out_unlocked:
1669         return ret;
1670 }
1671
1672 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1673 {
1674         pgtable_t pgtable;
1675
1676         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1677         pte_free(mm, pgtable);
1678         atomic_long_dec(&mm->nr_ptes);
1679 }
1680
1681 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1682                  pmd_t *pmd, unsigned long addr)
1683 {
1684         pmd_t orig_pmd;
1685         spinlock_t *ptl;
1686
1687         tlb_remove_check_page_size_change(tlb, HPAGE_PMD_SIZE);
1688
1689         ptl = __pmd_trans_huge_lock(pmd, vma);
1690         if (!ptl)
1691                 return 0;
1692         /*
1693          * For architectures like ppc64 we look at deposited pgtable
1694          * when calling pmdp_huge_get_and_clear. So do the
1695          * pgtable_trans_huge_withdraw after finishing pmdp related
1696          * operations.
1697          */
1698         orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
1699                         tlb->fullmm);
1700         tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1701         if (vma_is_dax(vma)) {
1702                 if (arch_needs_pgtable_deposit())
1703                         zap_deposited_table(tlb->mm, pmd);
1704                 spin_unlock(ptl);
1705                 if (is_huge_zero_pmd(orig_pmd))
1706                         tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1707         } else if (is_huge_zero_pmd(orig_pmd)) {
1708                 zap_deposited_table(tlb->mm, pmd);
1709                 spin_unlock(ptl);
1710                 tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
1711         } else {
1712                 struct page *page = NULL;
1713                 int flush_needed = 1;
1714
1715                 if (pmd_present(orig_pmd)) {
1716                         page = pmd_page(orig_pmd);
1717                         page_remove_rmap(page, true);
1718                         VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1719                         VM_BUG_ON_PAGE(!PageHead(page), page);
1720                 } else if (thp_migration_supported()) {
1721                         swp_entry_t entry;
1722
1723                         VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1724                         entry = pmd_to_swp_entry(orig_pmd);
1725                         page = pfn_to_page(swp_offset(entry));
1726                         flush_needed = 0;
1727                 } else
1728                         WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1729
1730                 if (PageAnon(page)) {
1731                         zap_deposited_table(tlb->mm, pmd);
1732                         add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1733                 } else {
1734                         if (arch_needs_pgtable_deposit())
1735                                 zap_deposited_table(tlb->mm, pmd);
1736                         add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR);
1737                 }
1738
1739                 spin_unlock(ptl);
1740                 if (flush_needed)
1741                         tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1742         }
1743         return 1;
1744 }
1745
1746 #ifndef pmd_move_must_withdraw
1747 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1748                                          spinlock_t *old_pmd_ptl,
1749                                          struct vm_area_struct *vma)
1750 {
1751         /*
1752          * With split pmd lock we also need to move preallocated
1753          * PTE page table if new_pmd is on different PMD page table.
1754          *
1755          * We also don't deposit and withdraw tables for file pages.
1756          */
1757         return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1758 }
1759 #endif
1760
1761 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1762 {
1763 #ifdef CONFIG_MEM_SOFT_DIRTY
1764         if (unlikely(is_pmd_migration_entry(pmd)))
1765                 pmd = pmd_swp_mksoft_dirty(pmd);
1766         else if (pmd_present(pmd))
1767                 pmd = pmd_mksoft_dirty(pmd);
1768 #endif
1769         return pmd;
1770 }
1771
1772 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1773                   unsigned long new_addr, unsigned long old_end,
1774                   pmd_t *old_pmd, pmd_t *new_pmd, bool *need_flush)
1775 {
1776         spinlock_t *old_ptl, *new_ptl;
1777         pmd_t pmd;
1778         struct mm_struct *mm = vma->vm_mm;
1779         bool force_flush = false;
1780
1781         if ((old_addr & ~HPAGE_PMD_MASK) ||
1782             (new_addr & ~HPAGE_PMD_MASK) ||
1783             old_end - old_addr < HPAGE_PMD_SIZE)
1784                 return false;
1785
1786         /*
1787          * The destination pmd shouldn't be established, free_pgtables()
1788          * should have release it.
1789          */
1790         if (WARN_ON(!pmd_none(*new_pmd))) {
1791                 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1792                 return false;
1793         }
1794
1795         /*
1796          * We don't have to worry about the ordering of src and dst
1797          * ptlocks because exclusive mmap_sem prevents deadlock.
1798          */
1799         old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1800         if (old_ptl) {
1801                 new_ptl = pmd_lockptr(mm, new_pmd);
1802                 if (new_ptl != old_ptl)
1803                         spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1804                 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1805                 if (pmd_present(pmd) && pmd_dirty(pmd))
1806                         force_flush = true;
1807                 VM_BUG_ON(!pmd_none(*new_pmd));
1808
1809                 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
1810                         pgtable_t pgtable;
1811                         pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
1812                         pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
1813                 }
1814                 pmd = move_soft_dirty_pmd(pmd);
1815                 set_pmd_at(mm, new_addr, new_pmd, pmd);
1816                 if (new_ptl != old_ptl)
1817                         spin_unlock(new_ptl);
1818                 if (force_flush)
1819                         flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
1820                 else
1821                         *need_flush = true;
1822                 spin_unlock(old_ptl);
1823                 return true;
1824         }
1825         return false;
1826 }
1827
1828 /*
1829  * Returns
1830  *  - 0 if PMD could not be locked
1831  *  - 1 if PMD was locked but protections unchange and TLB flush unnecessary
1832  *  - HPAGE_PMD_NR is protections changed and TLB flush necessary
1833  */
1834 int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
1835                 unsigned long addr, pgprot_t newprot, int prot_numa)
1836 {
1837         struct mm_struct *mm = vma->vm_mm;
1838         spinlock_t *ptl;
1839         pmd_t entry;
1840         bool preserve_write;
1841         int ret;
1842
1843         ptl = __pmd_trans_huge_lock(pmd, vma);
1844         if (!ptl)
1845                 return 0;
1846
1847         preserve_write = prot_numa && pmd_write(*pmd);
1848         ret = 1;
1849
1850 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1851         if (is_swap_pmd(*pmd)) {
1852                 swp_entry_t entry = pmd_to_swp_entry(*pmd);
1853
1854                 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
1855                 if (is_write_migration_entry(entry)) {
1856                         pmd_t newpmd;
1857                         /*
1858                          * A protection check is difficult so
1859                          * just be safe and disable write
1860                          */
1861                         make_migration_entry_read(&entry);
1862                         newpmd = swp_entry_to_pmd(entry);
1863                         if (pmd_swp_soft_dirty(*pmd))
1864                                 newpmd = pmd_swp_mksoft_dirty(newpmd);
1865                         set_pmd_at(mm, addr, pmd, newpmd);
1866                 }
1867                 goto unlock;
1868         }
1869 #endif
1870
1871         /*
1872          * Avoid trapping faults against the zero page. The read-only
1873          * data is likely to be read-cached on the local CPU and
1874          * local/remote hits to the zero page are not interesting.
1875          */
1876         if (prot_numa && is_huge_zero_pmd(*pmd))
1877                 goto unlock;
1878
1879         if (prot_numa && pmd_protnone(*pmd))
1880                 goto unlock;
1881
1882         /*
1883          * In case prot_numa, we are under down_read(mmap_sem). It's critical
1884          * to not clear pmd intermittently to avoid race with MADV_DONTNEED
1885          * which is also under down_read(mmap_sem):
1886          *
1887          *      CPU0:                           CPU1:
1888          *                              change_huge_pmd(prot_numa=1)
1889          *                               pmdp_huge_get_and_clear_notify()
1890          * madvise_dontneed()
1891          *  zap_pmd_range()
1892          *   pmd_trans_huge(*pmd) == 0 (without ptl)
1893          *   // skip the pmd
1894          *                               set_pmd_at();
1895          *                               // pmd is re-established
1896          *
1897          * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
1898          * which may break userspace.
1899          *
1900          * pmdp_invalidate() is required to make sure we don't miss
1901          * dirty/young flags set by hardware.
1902          */
1903         entry = *pmd;
1904         pmdp_invalidate(vma, addr, pmd);
1905
1906         /*
1907          * Recover dirty/young flags.  It relies on pmdp_invalidate to not
1908          * corrupt them.
1909          */
1910         if (pmd_dirty(*pmd))
1911                 entry = pmd_mkdirty(entry);
1912         if (pmd_young(*pmd))
1913                 entry = pmd_mkyoung(entry);
1914
1915         entry = pmd_modify(entry, newprot);
1916         if (preserve_write)
1917                 entry = pmd_mk_savedwrite(entry);
1918         ret = HPAGE_PMD_NR;
1919         set_pmd_at(mm, addr, pmd, entry);
1920         BUG_ON(vma_is_anonymous(vma) && !preserve_write && pmd_write(entry));
1921 unlock:
1922         spin_unlock(ptl);
1923         return ret;
1924 }
1925
1926 /*
1927  * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
1928  *
1929  * Note that if it returns page table lock pointer, this routine returns without
1930  * unlocking page table lock. So callers must unlock it.
1931  */
1932 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
1933 {
1934         spinlock_t *ptl;
1935         ptl = pmd_lock(vma->vm_mm, pmd);
1936         if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
1937                         pmd_devmap(*pmd)))
1938                 return ptl;
1939         spin_unlock(ptl);
1940         return NULL;
1941 }
1942
1943 /*
1944  * Returns true if a given pud maps a thp, false otherwise.
1945  *
1946  * Note that if it returns true, this routine returns without unlocking page
1947  * table lock. So callers must unlock it.
1948  */
1949 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
1950 {
1951         spinlock_t *ptl;
1952
1953         ptl = pud_lock(vma->vm_mm, pud);
1954         if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
1955                 return ptl;
1956         spin_unlock(ptl);
1957         return NULL;
1958 }
1959
1960 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1961 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
1962                  pud_t *pud, unsigned long addr)
1963 {
1964         pud_t orig_pud;
1965         spinlock_t *ptl;
1966
1967         ptl = __pud_trans_huge_lock(pud, vma);
1968         if (!ptl)
1969                 return 0;
1970         /*
1971          * For architectures like ppc64 we look at deposited pgtable
1972          * when calling pudp_huge_get_and_clear. So do the
1973          * pgtable_trans_huge_withdraw after finishing pudp related
1974          * operations.
1975          */
1976         orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud,
1977                         tlb->fullmm);
1978         tlb_remove_pud_tlb_entry(tlb, pud, addr);
1979         if (vma_is_dax(vma)) {
1980                 spin_unlock(ptl);
1981                 /* No zero page support yet */
1982         } else {
1983                 /* No support for anonymous PUD pages yet */
1984                 BUG();
1985         }
1986         return 1;
1987 }
1988
1989 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
1990                 unsigned long haddr)
1991 {
1992         VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
1993         VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
1994         VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
1995         VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
1996
1997         count_vm_event(THP_SPLIT_PUD);
1998
1999         pudp_huge_clear_flush_notify(vma, haddr, pud);
2000 }
2001
2002 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2003                 unsigned long address)
2004 {
2005         spinlock_t *ptl;
2006         struct mm_struct *mm = vma->vm_mm;
2007         unsigned long haddr = address & HPAGE_PUD_MASK;
2008
2009         mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PUD_SIZE);
2010         ptl = pud_lock(mm, pud);
2011         if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2012                 goto out;
2013         __split_huge_pud_locked(vma, pud, haddr);
2014
2015 out:
2016         spin_unlock(ptl);
2017         mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PUD_SIZE);
2018 }
2019 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2020
2021 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2022                 unsigned long haddr, pmd_t *pmd)
2023 {
2024         struct mm_struct *mm = vma->vm_mm;
2025         pgtable_t pgtable;
2026         pmd_t _pmd;
2027         int i;
2028
2029         /* leave pmd empty until pte is filled */
2030         pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2031
2032         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2033         pmd_populate(mm, &_pmd, pgtable);
2034
2035         for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
2036                 pte_t *pte, entry;
2037                 entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
2038                 entry = pte_mkspecial(entry);
2039                 pte = pte_offset_map(&_pmd, haddr);
2040                 VM_BUG_ON(!pte_none(*pte));
2041                 set_pte_at(mm, haddr, pte, entry);
2042                 pte_unmap(pte);
2043         }
2044         smp_wmb(); /* make pte visible before pmd */
2045         pmd_populate(mm, pmd, pgtable);
2046 }
2047
2048 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2049                 unsigned long haddr, bool freeze)
2050 {
2051         struct mm_struct *mm = vma->vm_mm;
2052         struct page *page;
2053         pgtable_t pgtable;
2054         pmd_t _pmd;
2055         bool young, write, dirty, soft_dirty, pmd_migration = false;
2056         unsigned long addr;
2057         int i;
2058
2059         VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2060         VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2061         VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2062         VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2063                                 && !pmd_devmap(*pmd));
2064
2065         count_vm_event(THP_SPLIT_PMD);
2066
2067         if (!vma_is_anonymous(vma)) {
2068                 _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
2069                 /*
2070                  * We are going to unmap this huge page. So
2071                  * just go ahead and zap it
2072                  */
2073                 if (arch_needs_pgtable_deposit())
2074                         zap_deposited_table(mm, pmd);
2075                 if (vma_is_dax(vma))
2076                         return;
2077                 page = pmd_page(_pmd);
2078                 if (!PageReferenced(page) && pmd_young(_pmd))
2079                         SetPageReferenced(page);
2080                 page_remove_rmap(page, true);
2081                 put_page(page);
2082                 add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
2083                 return;
2084         } else if (is_huge_zero_pmd(*pmd)) {
2085                 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2086         }
2087
2088 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2089         pmd_migration = is_pmd_migration_entry(*pmd);
2090         if (pmd_migration) {
2091                 swp_entry_t entry;
2092
2093                 entry = pmd_to_swp_entry(*pmd);
2094                 page = pfn_to_page(swp_offset(entry));
2095         } else
2096 #endif
2097                 page = pmd_page(*pmd);
2098         VM_BUG_ON_PAGE(!page_count(page), page);
2099         page_ref_add(page, HPAGE_PMD_NR - 1);
2100         write = pmd_write(*pmd);
2101         young = pmd_young(*pmd);
2102         dirty = pmd_dirty(*pmd);
2103         soft_dirty = pmd_soft_dirty(*pmd);
2104
2105         pmdp_huge_split_prepare(vma, haddr, pmd);
2106         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2107         pmd_populate(mm, &_pmd, pgtable);
2108
2109         for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2110                 pte_t entry, *pte;
2111                 /*
2112                  * Note that NUMA hinting access restrictions are not
2113                  * transferred to avoid any possibility of altering
2114                  * permissions across VMAs.
2115                  */
2116                 if (freeze || pmd_migration) {
2117                         swp_entry_t swp_entry;
2118                         swp_entry = make_migration_entry(page + i, write);
2119                         entry = swp_entry_to_pte(swp_entry);
2120                         if (soft_dirty)
2121                                 entry = pte_swp_mksoft_dirty(entry);
2122                 } else {
2123                         entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2124                         entry = maybe_mkwrite(entry, vma);
2125                         if (!write)
2126                                 entry = pte_wrprotect(entry);
2127                         if (!young)
2128                                 entry = pte_mkold(entry);
2129                         if (soft_dirty)
2130                                 entry = pte_mksoft_dirty(entry);
2131                 }
2132                 if (dirty)
2133                         SetPageDirty(page + i);
2134                 pte = pte_offset_map(&_pmd, addr);
2135                 BUG_ON(!pte_none(*pte));
2136                 set_pte_at(mm, addr, pte, entry);
2137                 atomic_inc(&page[i]._mapcount);
2138                 pte_unmap(pte);
2139         }
2140
2141         /*
2142          * Set PG_double_map before dropping compound_mapcount to avoid
2143          * false-negative page_mapped().
2144          */
2145         if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) {
2146                 for (i = 0; i < HPAGE_PMD_NR; i++)
2147                         atomic_inc(&page[i]._mapcount);
2148         }
2149
2150         if (atomic_add_negative(-1, compound_mapcount_ptr(page))) {
2151                 /* Last compound_mapcount is gone. */
2152                 __dec_node_page_state(page, NR_ANON_THPS);
2153                 if (TestClearPageDoubleMap(page)) {
2154                         /* No need in mapcount reference anymore */
2155                         for (i = 0; i < HPAGE_PMD_NR; i++)
2156                                 atomic_dec(&page[i]._mapcount);
2157                 }
2158         }
2159
2160         smp_wmb(); /* make pte visible before pmd */
2161         /*
2162          * Up to this point the pmd is present and huge and userland has the
2163          * whole access to the hugepage during the split (which happens in
2164          * place). If we overwrite the pmd with the not-huge version pointing
2165          * to the pte here (which of course we could if all CPUs were bug
2166          * free), userland could trigger a small page size TLB miss on the
2167          * small sized TLB while the hugepage TLB entry is still established in
2168          * the huge TLB. Some CPU doesn't like that.
2169          * See http://support.amd.com/us/Processor_TechDocs/41322.pdf, Erratum
2170          * 383 on page 93. Intel should be safe but is also warns that it's
2171          * only safe if the permission and cache attributes of the two entries
2172          * loaded in the two TLB is identical (which should be the case here).
2173          * But it is generally safer to never allow small and huge TLB entries
2174          * for the same virtual address to be loaded simultaneously. So instead
2175          * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2176          * current pmd notpresent (atomically because here the pmd_trans_huge
2177          * and pmd_trans_splitting must remain set at all times on the pmd
2178          * until the split is complete for this pmd), then we flush the SMP TLB
2179          * and finally we write the non-huge version of the pmd entry with
2180          * pmd_populate.
2181          */
2182         pmdp_invalidate(vma, haddr, pmd);
2183         pmd_populate(mm, pmd, pgtable);
2184
2185         if (freeze) {
2186                 for (i = 0; i < HPAGE_PMD_NR; i++) {
2187                         page_remove_rmap(page + i, false);
2188                         put_page(page + i);
2189                 }
2190         }
2191 }
2192
2193 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2194                 unsigned long address, bool freeze, struct page *page)
2195 {
2196         spinlock_t *ptl;
2197         struct mm_struct *mm = vma->vm_mm;
2198         unsigned long haddr = address & HPAGE_PMD_MASK;
2199
2200         mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
2201         ptl = pmd_lock(mm, pmd);
2202
2203         /*
2204          * If caller asks to setup a migration entries, we need a page to check
2205          * pmd against. Otherwise we can end up replacing wrong page.
2206          */
2207         VM_BUG_ON(freeze && !page);
2208         if (page && page != pmd_page(*pmd))
2209                 goto out;
2210
2211         if (pmd_trans_huge(*pmd)) {
2212                 page = pmd_page(*pmd);
2213                 if (PageMlocked(page))
2214                         clear_page_mlock(page);
2215         } else if (!(pmd_devmap(*pmd) || is_pmd_migration_entry(*pmd)))
2216                 goto out;
2217         __split_huge_pmd_locked(vma, pmd, haddr, freeze);
2218 out:
2219         spin_unlock(ptl);
2220         mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE);
2221 }
2222
2223 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2224                 bool freeze, struct page *page)
2225 {
2226         pgd_t *pgd;
2227         p4d_t *p4d;
2228         pud_t *pud;
2229         pmd_t *pmd;
2230
2231         pgd = pgd_offset(vma->vm_mm, address);
2232         if (!pgd_present(*pgd))
2233                 return;
2234
2235         p4d = p4d_offset(pgd, address);
2236         if (!p4d_present(*p4d))
2237                 return;
2238
2239         pud = pud_offset(p4d, address);
2240         if (!pud_present(*pud))
2241                 return;
2242
2243         pmd = pmd_offset(pud, address);
2244
2245         __split_huge_pmd(vma, pmd, address, freeze, page);
2246 }
2247
2248 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2249                              unsigned long start,
2250                              unsigned long end,
2251                              long adjust_next)
2252 {
2253         /*
2254          * If the new start address isn't hpage aligned and it could
2255          * previously contain an hugepage: check if we need to split
2256          * an huge pmd.
2257          */
2258         if (start & ~HPAGE_PMD_MASK &&
2259             (start & HPAGE_PMD_MASK) >= vma->vm_start &&
2260             (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2261                 split_huge_pmd_address(vma, start, false, NULL);
2262
2263         /*
2264          * If the new end address isn't hpage aligned and it could
2265          * previously contain an hugepage: check if we need to split
2266          * an huge pmd.
2267          */
2268         if (end & ~HPAGE_PMD_MASK &&
2269             (end & HPAGE_PMD_MASK) >= vma->vm_start &&
2270             (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
2271                 split_huge_pmd_address(vma, end, false, NULL);
2272
2273         /*
2274          * If we're also updating the vma->vm_next->vm_start, if the new
2275          * vm_next->vm_start isn't page aligned and it could previously
2276          * contain an hugepage: check if we need to split an huge pmd.
2277          */
2278         if (adjust_next > 0) {
2279                 struct vm_area_struct *next = vma->vm_next;
2280                 unsigned long nstart = next->vm_start;
2281                 nstart += adjust_next << PAGE_SHIFT;
2282                 if (nstart & ~HPAGE_PMD_MASK &&
2283                     (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
2284                     (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
2285                         split_huge_pmd_address(next, nstart, false, NULL);
2286         }
2287 }
2288
2289 static void freeze_page(struct page *page)
2290 {
2291         enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
2292                 TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
2293         bool unmap_success;
2294
2295         VM_BUG_ON_PAGE(!PageHead(page), page);
2296
2297         if (PageAnon(page))
2298                 ttu_flags |= TTU_SPLIT_FREEZE;
2299
2300         unmap_success = try_to_unmap(page, ttu_flags);
2301         VM_BUG_ON_PAGE(!unmap_success, page);
2302 }
2303
2304 static void unfreeze_page(struct page *page)
2305 {
2306         int i;
2307         if (PageTransHuge(page)) {
2308                 remove_migration_ptes(page, page, true);
2309         } else {
2310                 for (i = 0; i < HPAGE_PMD_NR; i++)
2311                         remove_migration_ptes(page + i, page + i, true);
2312         }
2313 }
2314
2315 static void __split_huge_page_tail(struct page *head, int tail,
2316                 struct lruvec *lruvec, struct list_head *list)
2317 {
2318         struct page *page_tail = head + tail;
2319
2320         VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2321         VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail);
2322
2323         /*
2324          * tail_page->_refcount is zero and not changing from under us. But
2325          * get_page_unless_zero() may be running from under us on the
2326          * tail_page. If we used atomic_set() below instead of atomic_inc() or
2327          * atomic_add(), we would then run atomic_set() concurrently with
2328          * get_page_unless_zero(), and atomic_set() is implemented in C not
2329          * using locked ops. spin_unlock on x86 sometime uses locked ops
2330          * because of PPro errata 66, 92, so unless somebody can guarantee
2331          * atomic_set() here would be safe on all archs (and not only on x86),
2332          * it's safer to use atomic_inc()/atomic_add().
2333          */
2334         if (PageAnon(head) && !PageSwapCache(head)) {
2335                 page_ref_inc(page_tail);
2336         } else {
2337                 /* Additional pin to radix tree */
2338                 page_ref_add(page_tail, 2);
2339         }
2340
2341         page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2342         page_tail->flags |= (head->flags &
2343                         ((1L << PG_referenced) |
2344                          (1L << PG_swapbacked) |
2345                          (1L << PG_swapcache) |
2346                          (1L << PG_mlocked) |
2347                          (1L << PG_uptodate) |
2348                          (1L << PG_active) |
2349                          (1L << PG_locked) |
2350                          (1L << PG_unevictable) |
2351                          (1L << PG_dirty)));
2352
2353         /*
2354          * After clearing PageTail the gup refcount can be released.
2355          * Page flags also must be visible before we make the page non-compound.
2356          */
2357         smp_wmb();
2358
2359         clear_compound_head(page_tail);
2360
2361         if (page_is_young(head))
2362                 set_page_young(page_tail);
2363         if (page_is_idle(head))
2364                 set_page_idle(page_tail);
2365
2366         /* ->mapping in first tail page is compound_mapcount */
2367         VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2368                         page_tail);
2369         page_tail->mapping = head->mapping;
2370
2371         page_tail->index = head->index + tail;
2372         page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
2373         lru_add_page_tail(head, page_tail, lruvec, list);
2374 }
2375
2376 static void __split_huge_page(struct page *page, struct list_head *list,
2377                 unsigned long flags)
2378 {
2379         struct page *head = compound_head(page);
2380         struct zone *zone = page_zone(head);
2381         struct lruvec *lruvec;
2382         pgoff_t end = -1;
2383         int i;
2384
2385         lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
2386
2387         /* complete memcg works before add pages to LRU */
2388         mem_cgroup_split_huge_fixup(head);
2389
2390         if (!PageAnon(page))
2391                 end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
2392
2393         for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
2394                 __split_huge_page_tail(head, i, lruvec, list);
2395                 /* Some pages can be beyond i_size: drop them from page cache */
2396                 if (head[i].index >= end) {
2397                         __ClearPageDirty(head + i);
2398                         __delete_from_page_cache(head + i, NULL);
2399                         if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
2400                                 shmem_uncharge(head->mapping->host, 1);
2401                         put_page(head + i);
2402                 }
2403         }
2404
2405         ClearPageCompound(head);
2406         /* See comment in __split_huge_page_tail() */
2407         if (PageAnon(head)) {
2408                 /* Additional pin to radix tree of swap cache */
2409                 if (PageSwapCache(head))
2410                         page_ref_add(head, 2);
2411                 else
2412                         page_ref_inc(head);
2413         } else {
2414                 /* Additional pin to radix tree */
2415                 page_ref_add(head, 2);
2416                 spin_unlock(&head->mapping->tree_lock);
2417         }
2418
2419         spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2420
2421         unfreeze_page(head);
2422
2423         for (i = 0; i < HPAGE_PMD_NR; i++) {
2424                 struct page *subpage = head + i;
2425                 if (subpage == page)
2426                         continue;
2427                 unlock_page(subpage);
2428
2429                 /*
2430                  * Subpages may be freed if there wasn't any mapping
2431                  * like if add_to_swap() is running on a lru page that
2432                  * had its mapping zapped. And freeing these pages
2433                  * requires taking the lru_lock so we do the put_page
2434                  * of the tail pages after the split is complete.
2435                  */
2436                 put_page(subpage);
2437         }
2438 }
2439
2440 int total_mapcount(struct page *page)
2441 {
2442         int i, compound, ret;
2443
2444         VM_BUG_ON_PAGE(PageTail(page), page);
2445
2446         if (likely(!PageCompound(page)))
2447                 return atomic_read(&page->_mapcount) + 1;
2448
2449         compound = compound_mapcount(page);
2450         if (PageHuge(page))
2451                 return compound;
2452         ret = compound;
2453         for (i = 0; i < HPAGE_PMD_NR; i++)
2454                 ret += atomic_read(&page[i]._mapcount) + 1;
2455         /* File pages has compound_mapcount included in _mapcount */
2456         if (!PageAnon(page))
2457                 return ret - compound * HPAGE_PMD_NR;
2458         if (PageDoubleMap(page))
2459                 ret -= HPAGE_PMD_NR;
2460         return ret;
2461 }
2462
2463 /*
2464  * This calculates accurately how many mappings a transparent hugepage
2465  * has (unlike page_mapcount() which isn't fully accurate). This full
2466  * accuracy is primarily needed to know if copy-on-write faults can
2467  * reuse the page and change the mapping to read-write instead of
2468  * copying them. At the same time this returns the total_mapcount too.
2469  *
2470  * The function returns the highest mapcount any one of the subpages
2471  * has. If the return value is one, even if different processes are
2472  * mapping different subpages of the transparent hugepage, they can
2473  * all reuse it, because each process is reusing a different subpage.
2474  *
2475  * The total_mapcount is instead counting all virtual mappings of the
2476  * subpages. If the total_mapcount is equal to "one", it tells the
2477  * caller all mappings belong to the same "mm" and in turn the
2478  * anon_vma of the transparent hugepage can become the vma->anon_vma
2479  * local one as no other process may be mapping any of the subpages.
2480  *
2481  * It would be more accurate to replace page_mapcount() with
2482  * page_trans_huge_mapcount(), however we only use
2483  * page_trans_huge_mapcount() in the copy-on-write faults where we
2484  * need full accuracy to avoid breaking page pinning, because
2485  * page_trans_huge_mapcount() is slower than page_mapcount().
2486  */
2487 int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
2488 {
2489         int i, ret, _total_mapcount, mapcount;
2490
2491         /* hugetlbfs shouldn't call it */
2492         VM_BUG_ON_PAGE(PageHuge(page), page);
2493
2494         if (likely(!PageTransCompound(page))) {
2495                 mapcount = atomic_read(&page->_mapcount) + 1;
2496                 if (total_mapcount)
2497                         *total_mapcount = mapcount;
2498                 return mapcount;
2499         }
2500
2501         page = compound_head(page);
2502
2503         _total_mapcount = ret = 0;
2504         for (i = 0; i < HPAGE_PMD_NR; i++) {
2505                 mapcount = atomic_read(&page[i]._mapcount) + 1;
2506                 ret = max(ret, mapcount);
2507                 _total_mapcount += mapcount;
2508         }
2509         if (PageDoubleMap(page)) {
2510                 ret -= 1;
2511                 _total_mapcount -= HPAGE_PMD_NR;
2512         }
2513         mapcount = compound_mapcount(page);
2514         ret += mapcount;
2515         _total_mapcount += mapcount;
2516         if (total_mapcount)
2517                 *total_mapcount = _total_mapcount;
2518         return ret;
2519 }
2520
2521 /* Racy check whether the huge page can be split */
2522 bool can_split_huge_page(struct page *page, int *pextra_pins)
2523 {
2524         int extra_pins;
2525
2526         /* Additional pins from radix tree */
2527         if (PageAnon(page))
2528                 extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
2529         else
2530                 extra_pins = HPAGE_PMD_NR;
2531         if (pextra_pins)
2532                 *pextra_pins = extra_pins;
2533         return total_mapcount(page) == page_count(page) - extra_pins - 1;
2534 }
2535
2536 /*
2537  * This function splits huge page into normal pages. @page can point to any
2538  * subpage of huge page to split. Split doesn't change the position of @page.
2539  *
2540  * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2541  * The huge page must be locked.
2542  *
2543  * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2544  *
2545  * Both head page and tail pages will inherit mapping, flags, and so on from
2546  * the hugepage.
2547  *
2548  * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2549  * they are not mapped.
2550  *
2551  * Returns 0 if the hugepage is split successfully.
2552  * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2553  * us.
2554  */
2555 int split_huge_page_to_list(struct page *page, struct list_head *list)
2556 {
2557         struct page *head = compound_head(page);
2558         struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));
2559         struct anon_vma *anon_vma = NULL;
2560         struct address_space *mapping = NULL;
2561         int count, mapcount, extra_pins, ret;
2562         bool mlocked;
2563         unsigned long flags;
2564
2565         VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
2566         VM_BUG_ON_PAGE(!PageLocked(page), page);
2567         VM_BUG_ON_PAGE(!PageCompound(page), page);
2568
2569         if (PageWriteback(page))
2570                 return -EBUSY;
2571
2572         if (PageAnon(head)) {
2573                 /*
2574                  * The caller does not necessarily hold an mmap_sem that would
2575                  * prevent the anon_vma disappearing so we first we take a
2576                  * reference to it and then lock the anon_vma for write. This
2577                  * is similar to page_lock_anon_vma_read except the write lock
2578                  * is taken to serialise against parallel split or collapse
2579                  * operations.
2580                  */
2581                 anon_vma = page_get_anon_vma(head);
2582                 if (!anon_vma) {
2583                         ret = -EBUSY;
2584                         goto out;
2585                 }
2586                 mapping = NULL;
2587                 anon_vma_lock_write(anon_vma);
2588         } else {
2589                 mapping = head->mapping;
2590
2591                 /* Truncated ? */
2592                 if (!mapping) {
2593                         ret = -EBUSY;
2594                         goto out;
2595                 }
2596
2597                 anon_vma = NULL;
2598                 i_mmap_lock_read(mapping);
2599         }
2600
2601         /*
2602          * Racy check if we can split the page, before freeze_page() will
2603          * split PMDs
2604          */
2605         if (!can_split_huge_page(head, &extra_pins)) {
2606                 ret = -EBUSY;
2607                 goto out_unlock;
2608         }
2609
2610         mlocked = PageMlocked(page);
2611         freeze_page(head);
2612         VM_BUG_ON_PAGE(compound_mapcount(head), head);
2613
2614         /* Make sure the page is not on per-CPU pagevec as it takes pin */
2615         if (mlocked)
2616                 lru_add_drain();
2617
2618         /* prevent PageLRU to go away from under us, and freeze lru stats */
2619         spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
2620
2621         if (mapping) {
2622                 void **pslot;
2623
2624                 spin_lock(&mapping->tree_lock);
2625                 pslot = radix_tree_lookup_slot(&mapping->page_tree,
2626                                 page_index(head));
2627                 /*
2628                  * Check if the head page is present in radix tree.
2629                  * We assume all tail are present too, if head is there.
2630                  */
2631                 if (radix_tree_deref_slot_protected(pslot,
2632                                         &mapping->tree_lock) != head)
2633                         goto fail;
2634         }
2635
2636         /* Prevent deferred_split_scan() touching ->_refcount */
2637         spin_lock(&pgdata->split_queue_lock);
2638         count = page_count(head);
2639         mapcount = total_mapcount(head);
2640         if (!mapcount && page_ref_freeze(head, 1 + extra_pins)) {
2641                 if (!list_empty(page_deferred_list(head))) {
2642                         pgdata->split_queue_len--;
2643                         list_del(page_deferred_list(head));
2644                 }
2645                 if (mapping)
2646                         __dec_node_page_state(page, NR_SHMEM_THPS);
2647                 spin_unlock(&pgdata->split_queue_lock);
2648                 __split_huge_page(page, list, flags);
2649                 if (PageSwapCache(head)) {
2650                         swp_entry_t entry = { .val = page_private(head) };
2651
2652                         ret = split_swap_cluster(entry);
2653                 } else
2654                         ret = 0;
2655         } else {
2656                 if (IS_ENABLED(CONFIG_DEBUG_VM) && mapcount) {
2657                         pr_alert("total_mapcount: %u, page_count(): %u\n",
2658                                         mapcount, count);
2659                         if (PageTail(page))
2660                                 dump_page(head, NULL);
2661                         dump_page(page, "total_mapcount(head) > 0");
2662                         BUG();
2663                 }
2664                 spin_unlock(&pgdata->split_queue_lock);
2665 fail:           if (mapping)
2666                         spin_unlock(&mapping->tree_lock);
2667                 spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
2668                 unfreeze_page(head);
2669                 ret = -EBUSY;
2670         }
2671
2672 out_unlock:
2673         if (anon_vma) {
2674                 anon_vma_unlock_write(anon_vma);
2675                 put_anon_vma(anon_vma);
2676         }
2677         if (mapping)
2678                 i_mmap_unlock_read(mapping);
2679 out:
2680         count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
2681         return ret;
2682 }
2683
2684 void free_transhuge_page(struct page *page)
2685 {
2686         struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2687         unsigned long flags;
2688
2689         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2690         if (!list_empty(page_deferred_list(page))) {
2691                 pgdata->split_queue_len--;
2692                 list_del(page_deferred_list(page));
2693         }
2694         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2695         free_compound_page(page);
2696 }
2697
2698 void deferred_split_huge_page(struct page *page)
2699 {
2700         struct pglist_data *pgdata = NODE_DATA(page_to_nid(page));
2701         unsigned long flags;
2702
2703         VM_BUG_ON_PAGE(!PageTransHuge(page), page);
2704
2705         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2706         if (list_empty(page_deferred_list(page))) {
2707                 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
2708                 list_add_tail(page_deferred_list(page), &pgdata->split_queue);
2709                 pgdata->split_queue_len++;
2710         }
2711         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2712 }
2713
2714 static unsigned long deferred_split_count(struct shrinker *shrink,
2715                 struct shrink_control *sc)
2716 {
2717         struct pglist_data *pgdata = NODE_DATA(sc->nid);
2718         return ACCESS_ONCE(pgdata->split_queue_len);
2719 }
2720
2721 static unsigned long deferred_split_scan(struct shrinker *shrink,
2722                 struct shrink_control *sc)
2723 {
2724         struct pglist_data *pgdata = NODE_DATA(sc->nid);
2725         unsigned long flags;
2726         LIST_HEAD(list), *pos, *next;
2727         struct page *page;
2728         int split = 0;
2729
2730         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2731         /* Take pin on all head pages to avoid freeing them under us */
2732         list_for_each_safe(pos, next, &pgdata->split_queue) {
2733                 page = list_entry((void *)pos, struct page, mapping);
2734                 page = compound_head(page);
2735                 if (get_page_unless_zero(page)) {
2736                         list_move(page_deferred_list(page), &list);
2737                 } else {
2738                         /* We lost race with put_compound_page() */
2739                         list_del_init(page_deferred_list(page));
2740                         pgdata->split_queue_len--;
2741                 }
2742                 if (!--sc->nr_to_scan)
2743                         break;
2744         }
2745         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2746
2747         list_for_each_safe(pos, next, &list) {
2748                 page = list_entry((void *)pos, struct page, mapping);
2749                 lock_page(page);
2750                 /* split_huge_page() removes page from list on success */
2751                 if (!split_huge_page(page))
2752                         split++;
2753                 unlock_page(page);
2754                 put_page(page);
2755         }
2756
2757         spin_lock_irqsave(&pgdata->split_queue_lock, flags);
2758         list_splice_tail(&list, &pgdata->split_queue);
2759         spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);
2760
2761         /*
2762          * Stop shrinker if we didn't split any page, but the queue is empty.
2763          * This can happen if pages were freed under us.
2764          */
2765         if (!split && list_empty(&pgdata->split_queue))
2766                 return SHRINK_STOP;
2767         return split;
2768 }
2769
2770 static struct shrinker deferred_split_shrinker = {
2771         .count_objects = deferred_split_count,
2772         .scan_objects = deferred_split_scan,
2773         .seeks = DEFAULT_SEEKS,
2774         .flags = SHRINKER_NUMA_AWARE,
2775 };
2776
2777 #ifdef CONFIG_DEBUG_FS
2778 static int split_huge_pages_set(void *data, u64 val)
2779 {
2780         struct zone *zone;
2781         struct page *page;
2782         unsigned long pfn, max_zone_pfn;
2783         unsigned long total = 0, split = 0;
2784
2785         if (val != 1)
2786                 return -EINVAL;
2787
2788         for_each_populated_zone(zone) {
2789                 max_zone_pfn = zone_end_pfn(zone);
2790                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
2791                         if (!pfn_valid(pfn))
2792                                 continue;
2793
2794                         page = pfn_to_page(pfn);
2795                         if (!get_page_unless_zero(page))
2796                                 continue;
2797
2798                         if (zone != page_zone(page))
2799                                 goto next;
2800
2801                         if (!PageHead(page) || PageHuge(page) || !PageLRU(page))
2802                                 goto next;
2803
2804                         total++;
2805                         lock_page(page);
2806                         if (!split_huge_page(page))
2807                                 split++;
2808                         unlock_page(page);
2809 next:
2810                         put_page(page);
2811                 }
2812         }
2813
2814         pr_info("%lu of %lu THP split\n", split, total);
2815
2816         return 0;
2817 }
2818 DEFINE_SIMPLE_ATTRIBUTE(split_huge_pages_fops, NULL, split_huge_pages_set,
2819                 "%llu\n");
2820
2821 static int __init split_huge_pages_debugfs(void)
2822 {
2823         void *ret;
2824
2825         ret = debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
2826                         &split_huge_pages_fops);
2827         if (!ret)
2828                 pr_warn("Failed to create split_huge_pages in debugfs");
2829         return 0;
2830 }
2831 late_initcall(split_huge_pages_debugfs);
2832 #endif
2833
2834 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2835 void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
2836                 struct page *page)
2837 {
2838         struct vm_area_struct *vma = pvmw->vma;
2839         struct mm_struct *mm = vma->vm_mm;
2840         unsigned long address = pvmw->address;
2841         pmd_t pmdval;
2842         swp_entry_t entry;
2843         pmd_t pmdswp;
2844
2845         if (!(pvmw->pmd && !pvmw->pte))
2846                 return;
2847
2848         mmu_notifier_invalidate_range_start(mm, address,
2849                         address + HPAGE_PMD_SIZE);
2850
2851         flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
2852         pmdval = *pvmw->pmd;
2853         pmdp_invalidate(vma, address, pvmw->pmd);
2854         if (pmd_dirty(pmdval))
2855                 set_page_dirty(page);
2856         entry = make_migration_entry(page, pmd_write(pmdval));
2857         pmdswp = swp_entry_to_pmd(entry);
2858         if (pmd_soft_dirty(pmdval))
2859                 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
2860         set_pmd_at(mm, address, pvmw->pmd, pmdswp);
2861         page_remove_rmap(page, true);
2862         put_page(page);
2863
2864         mmu_notifier_invalidate_range_end(mm, address,
2865                         address + HPAGE_PMD_SIZE);
2866 }
2867
2868 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
2869 {
2870         struct vm_area_struct *vma = pvmw->vma;
2871         struct mm_struct *mm = vma->vm_mm;
2872         unsigned long address = pvmw->address;
2873         unsigned long mmun_start = address & HPAGE_PMD_MASK;
2874         pmd_t pmde;
2875         swp_entry_t entry;
2876
2877         if (!(pvmw->pmd && !pvmw->pte))
2878                 return;
2879
2880         entry = pmd_to_swp_entry(*pvmw->pmd);
2881         get_page(new);
2882         pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
2883         if (pmd_swp_soft_dirty(*pvmw->pmd))
2884                 pmde = pmd_mksoft_dirty(pmde);
2885         if (is_write_migration_entry(entry))
2886                 pmde = maybe_pmd_mkwrite(pmde, vma);
2887
2888         flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
2889         page_add_anon_rmap(new, vma, mmun_start, true);
2890         set_pmd_at(mm, mmun_start, pvmw->pmd, pmde);
2891         if (vma->vm_flags & VM_LOCKED)
2892                 mlock_vma_page(new);
2893         update_mmu_cache_pmd(vma, address, pvmw->pmd);
2894 }
2895 #endif