mm/huge_memory.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Copyright (C) 2009  Red Hat, Inc.
   4  */
   5
   6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   7
   8 #include <linux/mm.h>
   9 #include <linux/sched.h>
  10 #include <linux/sched/mm.h>
  11 #include <linux/sched/coredump.h>
  12 #include <linux/sched/numa_balancing.h>
  13 #include <linux/highmem.h>
  14 #include <linux/hugetlb.h>
  15 #include <linux/mmu_notifier.h>
  16 #include <linux/rmap.h>
  17 #include <linux/swap.h>
  18 #include <linux/shrinker.h>
  19 #include <linux/mm_inline.h>
  20 #include <linux/swapops.h>
  21 #include <linux/backing-dev.h>
  22 #include <linux/dax.h>
  23 #include <linux/khugepaged.h>
  24 #include <linux/freezer.h>
  25 #include <linux/pfn_t.h>
  26 #include <linux/mman.h>
  27 #include <linux/memremap.h>
  28 #include <linux/pagemap.h>
  29 #include <linux/debugfs.h>
  30 #include <linux/migrate.h>
  31 #include <linux/hashtable.h>
  32 #include <linux/userfaultfd_k.h>
  33 #include <linux/page_idle.h>
  34 #include <linux/shmem_fs.h>
  35 #include <linux/oom.h>
  36 #include <linux/numa.h>
  37 #include <linux/page_owner.h>
  38 #include <linux/sched/sysctl.h>
  39 #include <linux/memory-tiers.h>
  40 #include <linux/compat.h>
  41
  42 #include <asm/tlb.h>
  43 #include <asm/pgalloc.h>
  44 #include "internal.h"
  45 #include "swap.h"
  46
  47 #define CREATE_TRACE_POINTS
  48 #include <trace/events/thp.h>
  49
  50 /*
  51  * By default, transparent hugepage support is disabled in order to avoid
  52  * risking an increased memory footprint for applications that are not
  53  * guaranteed to benefit from it. When transparent hugepage support is
  54  * enabled, it is for all mappings, and khugepaged scans all mappings.
  55  * Defrag is invoked by khugepaged hugepage allocations and by page faults
  56  * for all hugepage allocations.
  57  */
  58 unsigned long transparent_hugepage_flags __read_mostly =
  59 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS
  60         (1<<TRANSPARENT_HUGEPAGE_FLAG)|
  61 #endif
  62 #ifdef CONFIG_TRANSPARENT_HUGEPAGE_MADVISE
  63         (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG)|
  64 #endif
  65         (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG)|
  66         (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
  67         (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
  68
  69 static struct shrinker *deferred_split_shrinker;
  70 static unsigned long deferred_split_count(struct shrinker *shrink,
  71                                           struct shrink_control *sc);
  72 static unsigned long deferred_split_scan(struct shrinker *shrink,
  73                                          struct shrink_control *sc);
  74
  75 static atomic_t huge_zero_refcount;
  76 struct page *huge_zero_page __read_mostly;
  77 unsigned long huge_zero_pfn __read_mostly = ~0UL;
  78 unsigned long huge_anon_orders_always __read_mostly;
  79 unsigned long huge_anon_orders_madvise __read_mostly;
  80 unsigned long huge_anon_orders_inherit __read_mostly;
  81
  82 unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
  83                                          unsigned long vm_flags, bool smaps,
  84                                          bool in_pf, bool enforce_sysfs,
  85                                          unsigned long orders)
  86 {
  87         /* Check the intersection of requested and supported orders. */
  88         orders &= vma_is_anonymous(vma) ?
  89                         THP_ORDERS_ALL_ANON : THP_ORDERS_ALL_FILE;
  90         if (!orders)
  91                 return 0;
  92
  93         if (!vma->vm_mm)                /* vdso */
  94                 return 0;
  95
  96         /*
  97          * Explicitly disabled through madvise or prctl, or some
  98          * architectures may disable THP for some mappings, for
  99          * example, s390 kvm.
 100          * */
 101         if ((vm_flags & VM_NOHUGEPAGE) ||
 102             test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
 103                 return 0;
 104         /*
 105          * If the hardware/firmware marked hugepage support disabled.
 106          */
 107         if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED))
 108                 return 0;
 109
 110         /* khugepaged doesn't collapse DAX vma, but page fault is fine. */
 111         if (vma_is_dax(vma))
 112                 return in_pf ? orders : 0;
 113
 114         /*
 115          * khugepaged special VMA and hugetlb VMA.
 116          * Must be checked after dax since some dax mappings may have
 117          * VM_MIXEDMAP set.
 118          */
 119         if (!in_pf && !smaps && (vm_flags & VM_NO_KHUGEPAGED))
 120                 return 0;
 121
 122         /*
 123          * Check alignment for file vma and size for both file and anon vma by
 124          * filtering out the unsuitable orders.
 125          *
 126          * Skip the check for page fault. Huge fault does the check in fault
 127          * handlers.
 128          */
 129         if (!in_pf) {
 130                 int order = highest_order(orders);
 131                 unsigned long addr;
 132
 133                 while (orders) {
 134                         addr = vma->vm_end - (PAGE_SIZE << order);
 135                         if (thp_vma_suitable_order(vma, addr, order))
 136                                 break;
 137                         order = next_order(&orders, order);
 138                 }
 139
 140                 if (!orders)
 141                         return 0;
 142         }
 143
 144         /*
 145          * Enabled via shmem mount options or sysfs settings.
 146          * Must be done before hugepage flags check since shmem has its
 147          * own flags.
 148          */
 149         if (!in_pf && shmem_file(vma->vm_file))
 150                 return shmem_is_huge(file_inode(vma->vm_file), vma->vm_pgoff,
 151                                      !enforce_sysfs, vma->vm_mm, vm_flags)
 152                         ? orders : 0;
 153
 154         if (!vma_is_anonymous(vma)) {
 155                 /*
 156                  * Enforce sysfs THP requirements as necessary. Anonymous vmas
 157                  * were already handled in thp_vma_allowable_orders().
 158                  */
 159                 if (enforce_sysfs &&
 160                     (!hugepage_global_enabled() || (!(vm_flags & VM_HUGEPAGE) &&
 161                                                     !hugepage_global_always())))
 162                         return 0;
 163
 164                 /*
 165                  * Trust that ->huge_fault() handlers know what they are doing
 166                  * in fault path.
 167                  */
 168                 if (((in_pf || smaps)) && vma->vm_ops->huge_fault)
 169                         return orders;
 170                 /* Only regular file is valid in collapse path */
 171                 if (((!in_pf || smaps)) && file_thp_enabled(vma))
 172                         return orders;
 173                 return 0;
 174         }
 175
 176         if (vma_is_temporary_stack(vma))
 177                 return 0;
 178
 179         /*
 180          * THPeligible bit of smaps should show 1 for proper VMAs even
 181          * though anon_vma is not initialized yet.
 182          *
 183          * Allow page fault since anon_vma may be not initialized until
 184          * the first page fault.
 185          */
 186         if (!vma->anon_vma)
 187                 return (smaps || in_pf) ? orders : 0;
 188
 189         return orders;
 190 }
 191
 192 static bool get_huge_zero_page(void)
 193 {
 194         struct page *zero_page;
 195 retry:
 196         if (likely(atomic_inc_not_zero(&huge_zero_refcount)))
 197                 return true;
 198
 199         zero_page = alloc_pages((GFP_TRANSHUGE | __GFP_ZERO) & ~__GFP_MOVABLE,
 200                         HPAGE_PMD_ORDER);
 201         if (!zero_page) {
 202                 count_vm_event(THP_ZERO_PAGE_ALLOC_FAILED);
 203                 return false;
 204         }
 205         preempt_disable();
 206         if (cmpxchg(&huge_zero_page, NULL, zero_page)) {
 207                 preempt_enable();
 208                 __free_pages(zero_page, compound_order(zero_page));
 209                 goto retry;
 210         }
 211         WRITE_ONCE(huge_zero_pfn, page_to_pfn(zero_page));
 212
 213         /* We take additional reference here. It will be put back by shrinker */
 214         atomic_set(&huge_zero_refcount, 2);
 215         preempt_enable();
 216         count_vm_event(THP_ZERO_PAGE_ALLOC);
 217         return true;
 218 }
 219
 220 static void put_huge_zero_page(void)
 221 {
 222         /*
 223          * Counter should never go to zero here. Only shrinker can put
 224          * last reference.
 225          */
 226         BUG_ON(atomic_dec_and_test(&huge_zero_refcount));
 227 }
 228
 229 struct page *mm_get_huge_zero_page(struct mm_struct *mm)
 230 {
 231         if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
 232                 return READ_ONCE(huge_zero_page);
 233
 234         if (!get_huge_zero_page())
 235                 return NULL;
 236
 237         if (test_and_set_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
 238                 put_huge_zero_page();
 239
 240         return READ_ONCE(huge_zero_page);
 241 }
 242
 243 void mm_put_huge_zero_page(struct mm_struct *mm)
 244 {
 245         if (test_bit(MMF_HUGE_ZERO_PAGE, &mm->flags))
 246                 put_huge_zero_page();
 247 }
 248
 249 static unsigned long shrink_huge_zero_page_count(struct shrinker *shrink,
 250                                         struct shrink_control *sc)
 251 {
 252         /* we can free zero page only if last reference remains */
 253         return atomic_read(&huge_zero_refcount) == 1 ? HPAGE_PMD_NR : 0;
 254 }
 255
 256 static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
 257                                        struct shrink_control *sc)
 258 {
 259         if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) {
 260                 struct page *zero_page = xchg(&huge_zero_page, NULL);
 261                 BUG_ON(zero_page == NULL);
 262                 WRITE_ONCE(huge_zero_pfn, ~0UL);
 263                 __free_pages(zero_page, compound_order(zero_page));
 264                 return HPAGE_PMD_NR;
 265         }
 266
 267         return 0;
 268 }
 269
 270 static struct shrinker *huge_zero_page_shrinker;
 271
 272 #ifdef CONFIG_SYSFS
 273 static ssize_t enabled_show(struct kobject *kobj,
 274                             struct kobj_attribute *attr, char *buf)
 275 {
 276         const char *output;
 277
 278         if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags))
 279                 output = "[always] madvise never";
 280         else if (test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
 281                           &transparent_hugepage_flags))
 282                 output = "always [madvise] never";
 283         else
 284                 output = "always madvise [never]";
 285
 286         return sysfs_emit(buf, "%s\n", output);
 287 }
 288
 289 static ssize_t enabled_store(struct kobject *kobj,
 290                              struct kobj_attribute *attr,
 291                              const char *buf, size_t count)
 292 {
 293         ssize_t ret = count;
 294
 295         if (sysfs_streq(buf, "always")) {
 296                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
 297                 set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
 298         } else if (sysfs_streq(buf, "madvise")) {
 299                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
 300                 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
 301         } else if (sysfs_streq(buf, "never")) {
 302                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags);
 303                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags);
 304         } else
 305                 ret = -EINVAL;
 306
 307         if (ret > 0) {
 308                 int err = start_stop_khugepaged();
 309                 if (err)
 310                         ret = err;
 311         }
 312         return ret;
 313 }
 314
 315 static struct kobj_attribute enabled_attr = __ATTR_RW(enabled);
 316
 317 ssize_t single_hugepage_flag_show(struct kobject *kobj,
 318                                   struct kobj_attribute *attr, char *buf,
 319                                   enum transparent_hugepage_flag flag)
 320 {
 321         return sysfs_emit(buf, "%d\n",
 322                           !!test_bit(flag, &transparent_hugepage_flags));
 323 }
 324
 325 ssize_t single_hugepage_flag_store(struct kobject *kobj,
 326                                  struct kobj_attribute *attr,
 327                                  const char *buf, size_t count,
 328                                  enum transparent_hugepage_flag flag)
 329 {
 330         unsigned long value;
 331         int ret;
 332
 333         ret = kstrtoul(buf, 10, &value);
 334         if (ret < 0)
 335                 return ret;
 336         if (value > 1)
 337                 return -EINVAL;
 338
 339         if (value)
 340                 set_bit(flag, &transparent_hugepage_flags);
 341         else
 342                 clear_bit(flag, &transparent_hugepage_flags);
 343
 344         return count;
 345 }
 346
 347 static ssize_t defrag_show(struct kobject *kobj,
 348                            struct kobj_attribute *attr, char *buf)
 349 {
 350         const char *output;
 351
 352         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG,
 353                      &transparent_hugepage_flags))
 354                 output = "[always] defer defer+madvise madvise never";
 355         else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG,
 356                           &transparent_hugepage_flags))
 357                 output = "always [defer] defer+madvise madvise never";
 358         else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG,
 359                           &transparent_hugepage_flags))
 360                 output = "always defer [defer+madvise] madvise never";
 361         else if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
 362                           &transparent_hugepage_flags))
 363                 output = "always defer defer+madvise [madvise] never";
 364         else
 365                 output = "always defer defer+madvise madvise [never]";
 366
 367         return sysfs_emit(buf, "%s\n", output);
 368 }
 369
 370 static ssize_t defrag_store(struct kobject *kobj,
 371                             struct kobj_attribute *attr,
 372                             const char *buf, size_t count)
 373 {
 374         if (sysfs_streq(buf, "always")) {
 375                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 376                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 377                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 378                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 379         } else if (sysfs_streq(buf, "defer+madvise")) {
 380                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 381                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 382                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 383                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 384         } else if (sysfs_streq(buf, "defer")) {
 385                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 386                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 387                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 388                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 389         } else if (sysfs_streq(buf, "madvise")) {
 390                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 391                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 392                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 393                 set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 394         } else if (sysfs_streq(buf, "never")) {
 395                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags);
 396                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags);
 397                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags);
 398                 clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags);
 399         } else
 400                 return -EINVAL;
 401
 402         return count;
 403 }
 404 static struct kobj_attribute defrag_attr = __ATTR_RW(defrag);
 405
 406 static ssize_t use_zero_page_show(struct kobject *kobj,
 407                                   struct kobj_attribute *attr, char *buf)
 408 {
 409         return single_hugepage_flag_show(kobj, attr, buf,
 410                                          TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
 411 }
 412 static ssize_t use_zero_page_store(struct kobject *kobj,
 413                 struct kobj_attribute *attr, const char *buf, size_t count)
 414 {
 415         return single_hugepage_flag_store(kobj, attr, buf, count,
 416                                  TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
 417 }
 418 static struct kobj_attribute use_zero_page_attr = __ATTR_RW(use_zero_page);
 419
 420 static ssize_t hpage_pmd_size_show(struct kobject *kobj,
 421                                    struct kobj_attribute *attr, char *buf)
 422 {
 423         return sysfs_emit(buf, "%lu\n", HPAGE_PMD_SIZE);
 424 }
 425 static struct kobj_attribute hpage_pmd_size_attr =
 426         __ATTR_RO(hpage_pmd_size);
 427
 428 static struct attribute *hugepage_attr[] = {
 429         &enabled_attr.attr,
 430         &defrag_attr.attr,
 431         &use_zero_page_attr.attr,
 432         &hpage_pmd_size_attr.attr,
 433 #ifdef CONFIG_SHMEM
 434         &shmem_enabled_attr.attr,
 435 #endif
 436         NULL,
 437 };
 438
 439 static const struct attribute_group hugepage_attr_group = {
 440         .attrs = hugepage_attr,
 441 };
 442
 443 static void hugepage_exit_sysfs(struct kobject *hugepage_kobj);
 444 static void thpsize_release(struct kobject *kobj);
 445 static DEFINE_SPINLOCK(huge_anon_orders_lock);
 446 static LIST_HEAD(thpsize_list);
 447
 448 struct thpsize {
 449         struct kobject kobj;
 450         struct list_head node;
 451         int order;
 452 };
 453
 454 #define to_thpsize(kobj) container_of(kobj, struct thpsize, kobj)
 455
 456 static ssize_t thpsize_enabled_show(struct kobject *kobj,
 457                                     struct kobj_attribute *attr, char *buf)
 458 {
 459         int order = to_thpsize(kobj)->order;
 460         const char *output;
 461
 462         if (test_bit(order, &huge_anon_orders_always))
 463                 output = "[always] inherit madvise never";
 464         else if (test_bit(order, &huge_anon_orders_inherit))
 465                 output = "always [inherit] madvise never";
 466         else if (test_bit(order, &huge_anon_orders_madvise))
 467                 output = "always inherit [madvise] never";
 468         else
 469                 output = "always inherit madvise [never]";
 470
 471         return sysfs_emit(buf, "%s\n", output);
 472 }
 473
 474 static ssize_t thpsize_enabled_store(struct kobject *kobj,
 475                                      struct kobj_attribute *attr,
 476                                      const char *buf, size_t count)
 477 {
 478         int order = to_thpsize(kobj)->order;
 479         ssize_t ret = count;
 480
 481         if (sysfs_streq(buf, "always")) {
 482                 spin_lock(&huge_anon_orders_lock);
 483                 clear_bit(order, &huge_anon_orders_inherit);
 484                 clear_bit(order, &huge_anon_orders_madvise);
 485                 set_bit(order, &huge_anon_orders_always);
 486                 spin_unlock(&huge_anon_orders_lock);
 487         } else if (sysfs_streq(buf, "inherit")) {
 488                 spin_lock(&huge_anon_orders_lock);
 489                 clear_bit(order, &huge_anon_orders_always);
 490                 clear_bit(order, &huge_anon_orders_madvise);
 491                 set_bit(order, &huge_anon_orders_inherit);
 492                 spin_unlock(&huge_anon_orders_lock);
 493         } else if (sysfs_streq(buf, "madvise")) {
 494                 spin_lock(&huge_anon_orders_lock);
 495                 clear_bit(order, &huge_anon_orders_always);
 496                 clear_bit(order, &huge_anon_orders_inherit);
 497                 set_bit(order, &huge_anon_orders_madvise);
 498                 spin_unlock(&huge_anon_orders_lock);
 499         } else if (sysfs_streq(buf, "never")) {
 500                 spin_lock(&huge_anon_orders_lock);
 501                 clear_bit(order, &huge_anon_orders_always);
 502                 clear_bit(order, &huge_anon_orders_inherit);
 503                 clear_bit(order, &huge_anon_orders_madvise);
 504                 spin_unlock(&huge_anon_orders_lock);
 505         } else
 506                 ret = -EINVAL;
 507
 508         return ret;
 509 }
 510
 511 static struct kobj_attribute thpsize_enabled_attr =
 512         __ATTR(enabled, 0644, thpsize_enabled_show, thpsize_enabled_store);
 513
 514 static struct attribute *thpsize_attrs[] = {
 515         &thpsize_enabled_attr.attr,
 516         NULL,
 517 };
 518
 519 static const struct attribute_group thpsize_attr_group = {
 520         .attrs = thpsize_attrs,
 521 };
 522
 523 static const struct kobj_type thpsize_ktype = {
 524         .release = &thpsize_release,
 525         .sysfs_ops = &kobj_sysfs_ops,
 526 };
 527
 528 static struct thpsize *thpsize_create(int order, struct kobject *parent)
 529 {
 530         unsigned long size = (PAGE_SIZE << order) / SZ_1K;
 531         struct thpsize *thpsize;
 532         int ret;
 533
 534         thpsize = kzalloc(sizeof(*thpsize), GFP_KERNEL);
 535         if (!thpsize)
 536                 return ERR_PTR(-ENOMEM);
 537
 538         ret = kobject_init_and_add(&thpsize->kobj, &thpsize_ktype, parent,
 539                                    "hugepages-%lukB", size);
 540         if (ret) {
 541                 kfree(thpsize);
 542                 return ERR_PTR(ret);
 543         }
 544
 545         ret = sysfs_create_group(&thpsize->kobj, &thpsize_attr_group);
 546         if (ret) {
 547                 kobject_put(&thpsize->kobj);
 548                 return ERR_PTR(ret);
 549         }
 550
 551         thpsize->order = order;
 552         return thpsize;
 553 }
 554
 555 static void thpsize_release(struct kobject *kobj)
 556 {
 557         kfree(to_thpsize(kobj));
 558 }
 559
 560 static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
 561 {
 562         int err;
 563         struct thpsize *thpsize;
 564         unsigned long orders;
 565         int order;
 566
 567         /*
 568          * Default to setting PMD-sized THP to inherit the global setting and
 569          * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time
 570          * constant so we have to do this here.
 571          */
 572         huge_anon_orders_inherit = BIT(PMD_ORDER);
 573
 574         *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
 575         if (unlikely(!*hugepage_kobj)) {
 576                 pr_err("failed to create transparent hugepage kobject\n");
 577                 return -ENOMEM;
 578         }
 579
 580         err = sysfs_create_group(*hugepage_kobj, &hugepage_attr_group);
 581         if (err) {
 582                 pr_err("failed to register transparent hugepage group\n");
 583                 goto delete_obj;
 584         }
 585
 586         err = sysfs_create_group(*hugepage_kobj, &khugepaged_attr_group);
 587         if (err) {
 588                 pr_err("failed to register transparent hugepage group\n");
 589                 goto remove_hp_group;
 590         }
 591
 592         orders = THP_ORDERS_ALL_ANON;
 593         order = highest_order(orders);
 594         while (orders) {
 595                 thpsize = thpsize_create(order, *hugepage_kobj);
 596                 if (IS_ERR(thpsize)) {
 597                         pr_err("failed to create thpsize for order %d\n", order);
 598                         err = PTR_ERR(thpsize);
 599                         goto remove_all;
 600                 }
 601                 list_add(&thpsize->node, &thpsize_list);
 602                 order = next_order(&orders, order);
 603         }
 604
 605         return 0;
 606
 607 remove_all:
 608         hugepage_exit_sysfs(*hugepage_kobj);
 609         return err;
 610 remove_hp_group:
 611         sysfs_remove_group(*hugepage_kobj, &hugepage_attr_group);
 612 delete_obj:
 613         kobject_put(*hugepage_kobj);
 614         return err;
 615 }
 616
 617 static void __init hugepage_exit_sysfs(struct kobject *hugepage_kobj)
 618 {
 619         struct thpsize *thpsize, *tmp;
 620
 621         list_for_each_entry_safe(thpsize, tmp, &thpsize_list, node) {
 622                 list_del(&thpsize->node);
 623                 kobject_put(&thpsize->kobj);
 624         }
 625
 626         sysfs_remove_group(hugepage_kobj, &khugepaged_attr_group);
 627         sysfs_remove_group(hugepage_kobj, &hugepage_attr_group);
 628         kobject_put(hugepage_kobj);
 629 }
 630 #else
 631 static inline int hugepage_init_sysfs(struct kobject **hugepage_kobj)
 632 {
 633         return 0;
 634 }
 635
 636 static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
 637 {
 638 }
 639 #endif /* CONFIG_SYSFS */
 640
 641 static int __init thp_shrinker_init(void)
 642 {
 643         huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero");
 644         if (!huge_zero_page_shrinker)
 645                 return -ENOMEM;
 646
 647         deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE |
 648                                                  SHRINKER_MEMCG_AWARE |
 649                                                  SHRINKER_NONSLAB,
 650                                                  "thp-deferred_split");
 651         if (!deferred_split_shrinker) {
 652                 shrinker_free(huge_zero_page_shrinker);
 653                 return -ENOMEM;
 654         }
 655
 656         huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count;
 657         huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan;
 658         shrinker_register(huge_zero_page_shrinker);
 659
 660         deferred_split_shrinker->count_objects = deferred_split_count;
 661         deferred_split_shrinker->scan_objects = deferred_split_scan;
 662         shrinker_register(deferred_split_shrinker);
 663
 664         return 0;
 665 }
 666
 667 static void __init thp_shrinker_exit(void)
 668 {
 669         shrinker_free(huge_zero_page_shrinker);
 670         shrinker_free(deferred_split_shrinker);
 671 }
 672
 673 static int __init hugepage_init(void)
 674 {
 675         int err;
 676         struct kobject *hugepage_kobj;
 677
 678         if (!has_transparent_hugepage()) {
 679                 transparent_hugepage_flags = 1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED;
 680                 return -EINVAL;
 681         }
 682
 683         /*
 684          * hugepages can't be allocated by the buddy allocator
 685          */
 686         MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER > MAX_PAGE_ORDER);
 687         /*
 688          * we use page->mapping and page->index in second tail page
 689          * as list_head: assuming THP order >= 2
 690          */
 691         MAYBE_BUILD_BUG_ON(HPAGE_PMD_ORDER < 2);
 692
 693         err = hugepage_init_sysfs(&hugepage_kobj);
 694         if (err)
 695                 goto err_sysfs;
 696
 697         err = khugepaged_init();
 698         if (err)
 699                 goto err_slab;
 700
 701         err = thp_shrinker_init();
 702         if (err)
 703                 goto err_shrinker;
 704
 705         /*
 706          * By default disable transparent hugepages on smaller systems,
 707          * where the extra memory used could hurt more than TLB overhead
 708          * is likely to save.  The admin can still enable it through /sys.
 709          */
 710         if (totalram_pages() < (512 << (20 - PAGE_SHIFT))) {
 711                 transparent_hugepage_flags = 0;
 712                 return 0;
 713         }
 714
 715         err = start_stop_khugepaged();
 716         if (err)
 717                 goto err_khugepaged;
 718
 719         return 0;
 720 err_khugepaged:
 721         thp_shrinker_exit();
 722 err_shrinker:
 723         khugepaged_destroy();
 724 err_slab:
 725         hugepage_exit_sysfs(hugepage_kobj);
 726 err_sysfs:
 727         return err;
 728 }
 729 subsys_initcall(hugepage_init);
 730
 731 static int __init setup_transparent_hugepage(char *str)
 732 {
 733         int ret = 0;
 734         if (!str)
 735                 goto out;
 736         if (!strcmp(str, "always")) {
 737                 set_bit(TRANSPARENT_HUGEPAGE_FLAG,
 738                         &transparent_hugepage_flags);
 739                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
 740                           &transparent_hugepage_flags);
 741                 ret = 1;
 742         } else if (!strcmp(str, "madvise")) {
 743                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
 744                           &transparent_hugepage_flags);
 745                 set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
 746                         &transparent_hugepage_flags);
 747                 ret = 1;
 748         } else if (!strcmp(str, "never")) {
 749                 clear_bit(TRANSPARENT_HUGEPAGE_FLAG,
 750                           &transparent_hugepage_flags);
 751                 clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
 752                           &transparent_hugepage_flags);
 753                 ret = 1;
 754         }
 755 out:
 756         if (!ret)
 757                 pr_warn("transparent_hugepage= cannot parse, ignored\n");
 758         return ret;
 759 }
 760 __setup("transparent_hugepage=", setup_transparent_hugepage);
 761
 762 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
 763 {
 764         if (likely(vma->vm_flags & VM_WRITE))
 765                 pmd = pmd_mkwrite(pmd, vma);
 766         return pmd;
 767 }
 768
 769 #ifdef CONFIG_MEMCG
 770 static inline
 771 struct deferred_split *get_deferred_split_queue(struct folio *folio)
 772 {
 773         struct mem_cgroup *memcg = folio_memcg(folio);
 774         struct pglist_data *pgdat = NODE_DATA(folio_nid(folio));
 775
 776         if (memcg)
 777                 return &memcg->deferred_split_queue;
 778         else
 779                 return &pgdat->deferred_split_queue;
 780 }
 781 #else
 782 static inline
 783 struct deferred_split *get_deferred_split_queue(struct folio *folio)
 784 {
 785         struct pglist_data *pgdat = NODE_DATA(folio_nid(folio));
 786
 787         return &pgdat->deferred_split_queue;
 788 }
 789 #endif
 790
 791 void folio_prep_large_rmappable(struct folio *folio)
 792 {
 793         VM_BUG_ON_FOLIO(folio_order(folio) < 2, folio);
 794         INIT_LIST_HEAD(&folio->_deferred_list);
 795         folio_set_large_rmappable(folio);
 796 }
 797
 798 static inline bool is_transparent_hugepage(struct folio *folio)
 799 {
 800         if (!folio_test_large(folio))
 801                 return false;
 802
 803         return is_huge_zero_page(&folio->page) ||
 804                 folio_test_large_rmappable(folio);
 805 }
 806
 807 static unsigned long __thp_get_unmapped_area(struct file *filp,
 808                 unsigned long addr, unsigned long len,
 809                 loff_t off, unsigned long flags, unsigned long size)
 810 {
 811         loff_t off_end = off + len;
 812         loff_t off_align = round_up(off, size);
 813         unsigned long len_pad, ret, off_sub;
 814
 815         if (IS_ENABLED(CONFIG_32BIT) || in_compat_syscall())
 816                 return 0;
 817
 818         if (off_end <= off_align || (off_end - off_align) < size)
 819                 return 0;
 820
 821         len_pad = len + size;
 822         if (len_pad < len || (off + len_pad) < off)
 823                 return 0;
 824
 825         ret = current->mm->get_unmapped_area(filp, addr, len_pad,
 826                                               off >> PAGE_SHIFT, flags);
 827
 828         /*
 829          * The failure might be due to length padding. The caller will retry
 830          * without the padding.
 831          */
 832         if (IS_ERR_VALUE(ret))
 833                 return 0;
 834
 835         /*
 836          * Do not try to align to THP boundary if allocation at the address
 837          * hint succeeds.
 838          */
 839         if (ret == addr)
 840                 return addr;
 841
 842         off_sub = (off - ret) & (size - 1);
 843
 844         if (current->mm->get_unmapped_area == arch_get_unmapped_area_topdown &&
 845             !off_sub)
 846                 return ret + size;
 847
 848         ret += off_sub;
 849         return ret;
 850 }
 851
 852 unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
 853                 unsigned long len, unsigned long pgoff, unsigned long flags)
 854 {
 855         unsigned long ret;
 856         loff_t off = (loff_t)pgoff << PAGE_SHIFT;
 857
 858         ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
 859         if (ret)
 860                 return ret;
 861
 862         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 863 }
 864 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
 865
 866 static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf,
 867                         struct page *page, gfp_t gfp)
 868 {
 869         struct vm_area_struct *vma = vmf->vma;
 870         struct folio *folio = page_folio(page);
 871         pgtable_t pgtable;
 872         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
 873         vm_fault_t ret = 0;
 874
 875         VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
 876
 877         if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) {
 878                 folio_put(folio);
 879                 count_vm_event(THP_FAULT_FALLBACK);
 880                 count_vm_event(THP_FAULT_FALLBACK_CHARGE);
 881                 return VM_FAULT_FALLBACK;
 882         }
 883         folio_throttle_swaprate(folio, gfp);
 884
 885         pgtable = pte_alloc_one(vma->vm_mm);
 886         if (unlikely(!pgtable)) {
 887                 ret = VM_FAULT_OOM;
 888                 goto release;
 889         }
 890
 891         clear_huge_page(page, vmf->address, HPAGE_PMD_NR);
 892         /*
 893          * The memory barrier inside __folio_mark_uptodate makes sure that
 894          * clear_huge_page writes become visible before the set_pmd_at()
 895          * write.
 896          */
 897         __folio_mark_uptodate(folio);
 898
 899         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
 900         if (unlikely(!pmd_none(*vmf->pmd))) {
 901                 goto unlock_release;
 902         } else {
 903                 pmd_t entry;
 904
 905                 ret = check_stable_address_space(vma->vm_mm);
 906                 if (ret)
 907                         goto unlock_release;
 908
 909                 /* Deliver the page fault to userland */
 910                 if (userfaultfd_missing(vma)) {
 911                         spin_unlock(vmf->ptl);
 912                         folio_put(folio);
 913                         pte_free(vma->vm_mm, pgtable);
 914                         ret = handle_userfault(vmf, VM_UFFD_MISSING);
 915                         VM_BUG_ON(ret & VM_FAULT_FALLBACK);
 916                         return ret;
 917                 }
 918
 919                 entry = mk_huge_pmd(page, vma->vm_page_prot);
 920                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
 921                 folio_add_new_anon_rmap(folio, vma, haddr);
 922                 folio_add_lru_vma(folio, vma);
 923                 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
 924                 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
 925                 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
 926                 add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
 927                 mm_inc_nr_ptes(vma->vm_mm);
 928                 spin_unlock(vmf->ptl);
 929                 count_vm_event(THP_FAULT_ALLOC);
 930                 count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
 931         }
 932
 933         return 0;
 934 unlock_release:
 935         spin_unlock(vmf->ptl);
 936 release:
 937         if (pgtable)
 938                 pte_free(vma->vm_mm, pgtable);
 939         folio_put(folio);
 940         return ret;
 941
 942 }
 943
 944 /*
 945  * always: directly stall for all thp allocations
 946  * defer: wake kswapd and fail if not immediately available
 947  * defer+madvise: wake kswapd and directly stall for MADV_HUGEPAGE, otherwise
 948  *                fail if not immediately available
 949  * madvise: directly stall for MADV_HUGEPAGE, otherwise fail if not immediately
 950  *          available
 951  * never: never stall for any thp allocation
 952  */
 953 gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma)
 954 {
 955         const bool vma_madvised = vma && (vma->vm_flags & VM_HUGEPAGE);
 956
 957         /* Always do synchronous compaction */
 958         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags))
 959                 return GFP_TRANSHUGE | (vma_madvised ? 0 : __GFP_NORETRY);
 960
 961         /* Kick kcompactd and fail quickly */
 962         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags))
 963                 return GFP_TRANSHUGE_LIGHT | __GFP_KSWAPD_RECLAIM;
 964
 965         /* Synchronous compaction if madvised, otherwise kick kcompactd */
 966         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags))
 967                 return GFP_TRANSHUGE_LIGHT |
 968                         (vma_madvised ? __GFP_DIRECT_RECLAIM :
 969                                         __GFP_KSWAPD_RECLAIM);
 970
 971         /* Only do synchronous compaction if madvised */
 972         if (test_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags))
 973                 return GFP_TRANSHUGE_LIGHT |
 974                        (vma_madvised ? __GFP_DIRECT_RECLAIM : 0);
 975
 976         return GFP_TRANSHUGE_LIGHT;
 977 }
 978
 979 /* Caller must hold page table lock. */
 980 static void set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm,
 981                 struct vm_area_struct *vma, unsigned long haddr, pmd_t *pmd,
 982                 struct page *zero_page)
 983 {
 984         pmd_t entry;
 985         if (!pmd_none(*pmd))
 986                 return;
 987         entry = mk_pmd(zero_page, vma->vm_page_prot);
 988         entry = pmd_mkhuge(entry);
 989         pgtable_trans_huge_deposit(mm, pmd, pgtable);
 990         set_pmd_at(mm, haddr, pmd, entry);
 991         mm_inc_nr_ptes(mm);
 992 }
 993
 994 vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 995 {
 996         struct vm_area_struct *vma = vmf->vma;
 997         gfp_t gfp;
 998         struct folio *folio;
 999         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1000
1001         if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER))
1002                 return VM_FAULT_FALLBACK;
1003         if (unlikely(anon_vma_prepare(vma)))
1004                 return VM_FAULT_OOM;
1005         khugepaged_enter_vma(vma, vma->vm_flags);
1006
1007         if (!(vmf->flags & FAULT_FLAG_WRITE) &&
1008                         !mm_forbids_zeropage(vma->vm_mm) &&
1009                         transparent_hugepage_use_zero_page()) {
1010                 pgtable_t pgtable;
1011                 struct page *zero_page;
1012                 vm_fault_t ret;
1013                 pgtable = pte_alloc_one(vma->vm_mm);
1014                 if (unlikely(!pgtable))
1015                         return VM_FAULT_OOM;
1016                 zero_page = mm_get_huge_zero_page(vma->vm_mm);
1017                 if (unlikely(!zero_page)) {
1018                         pte_free(vma->vm_mm, pgtable);
1019                         count_vm_event(THP_FAULT_FALLBACK);
1020                         return VM_FAULT_FALLBACK;
1021                 }
1022                 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1023                 ret = 0;
1024                 if (pmd_none(*vmf->pmd)) {
1025                         ret = check_stable_address_space(vma->vm_mm);
1026                         if (ret) {
1027                                 spin_unlock(vmf->ptl);
1028                                 pte_free(vma->vm_mm, pgtable);
1029                         } else if (userfaultfd_missing(vma)) {
1030                                 spin_unlock(vmf->ptl);
1031                                 pte_free(vma->vm_mm, pgtable);
1032                                 ret = handle_userfault(vmf, VM_UFFD_MISSING);
1033                                 VM_BUG_ON(ret & VM_FAULT_FALLBACK);
1034                         } else {
1035                                 set_huge_zero_page(pgtable, vma->vm_mm, vma,
1036                                                    haddr, vmf->pmd, zero_page);
1037                                 update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1038                                 spin_unlock(vmf->ptl);
1039                         }
1040                 } else {
1041                         spin_unlock(vmf->ptl);
1042                         pte_free(vma->vm_mm, pgtable);
1043                 }
1044                 return ret;
1045         }
1046         gfp = vma_thp_gfp_mask(vma);
1047         folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true);
1048         if (unlikely(!folio)) {
1049                 count_vm_event(THP_FAULT_FALLBACK);
1050                 return VM_FAULT_FALLBACK;
1051         }
1052         return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp);
1053 }
1054
1055 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
1056                 pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
1057                 pgtable_t pgtable)
1058 {
1059         struct mm_struct *mm = vma->vm_mm;
1060         pmd_t entry;
1061         spinlock_t *ptl;
1062
1063         ptl = pmd_lock(mm, pmd);
1064         if (!pmd_none(*pmd)) {
1065                 if (write) {
1066                         if (pmd_pfn(*pmd) != pfn_t_to_pfn(pfn)) {
1067                                 WARN_ON_ONCE(!is_huge_zero_pmd(*pmd));
1068                                 goto out_unlock;
1069                         }
1070                         entry = pmd_mkyoung(*pmd);
1071                         entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1072                         if (pmdp_set_access_flags(vma, addr, pmd, entry, 1))
1073                                 update_mmu_cache_pmd(vma, addr, pmd);
1074                 }
1075
1076                 goto out_unlock;
1077         }
1078
1079         entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
1080         if (pfn_t_devmap(pfn))
1081                 entry = pmd_mkdevmap(entry);
1082         if (write) {
1083                 entry = pmd_mkyoung(pmd_mkdirty(entry));
1084                 entry = maybe_pmd_mkwrite(entry, vma);
1085         }
1086
1087         if (pgtable) {
1088                 pgtable_trans_huge_deposit(mm, pmd, pgtable);
1089                 mm_inc_nr_ptes(mm);
1090                 pgtable = NULL;
1091         }
1092
1093         set_pmd_at(mm, addr, pmd, entry);
1094         update_mmu_cache_pmd(vma, addr, pmd);
1095
1096 out_unlock:
1097         spin_unlock(ptl);
1098         if (pgtable)
1099                 pte_free(mm, pgtable);
1100 }
1101
1102 /**
1103  * vmf_insert_pfn_pmd - insert a pmd size pfn
1104  * @vmf: Structure describing the fault
1105  * @pfn: pfn to insert
1106  * @write: whether it's a write fault
1107  *
1108  * Insert a pmd size pfn. See vmf_insert_pfn() for additional info.
1109  *
1110  * Return: vm_fault_t value.
1111  */
1112 vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
1113 {
1114         unsigned long addr = vmf->address & PMD_MASK;
1115         struct vm_area_struct *vma = vmf->vma;
1116         pgprot_t pgprot = vma->vm_page_prot;
1117         pgtable_t pgtable = NULL;
1118
1119         /*
1120          * If we had pmd_special, we could avoid all these restrictions,
1121          * but we need to be consistent with PTEs and architectures that
1122          * can't support a 'special' bit.
1123          */
1124         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
1125                         !pfn_t_devmap(pfn));
1126         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1127                                                 (VM_PFNMAP|VM_MIXEDMAP));
1128         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1129
1130         if (addr < vma->vm_start || addr >= vma->vm_end)
1131                 return VM_FAULT_SIGBUS;
1132
1133         if (arch_needs_pgtable_deposit()) {
1134                 pgtable = pte_alloc_one(vma->vm_mm);
1135                 if (!pgtable)
1136                         return VM_FAULT_OOM;
1137         }
1138
1139         track_pfn_insert(vma, &pgprot, pfn);
1140
1141         insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
1142         return VM_FAULT_NOPAGE;
1143 }
1144 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
1145
1146 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1147 static pud_t maybe_pud_mkwrite(pud_t pud, struct vm_area_struct *vma)
1148 {
1149         if (likely(vma->vm_flags & VM_WRITE))
1150                 pud = pud_mkwrite(pud);
1151         return pud;
1152 }
1153
1154 static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
1155                 pud_t *pud, pfn_t pfn, bool write)
1156 {
1157         struct mm_struct *mm = vma->vm_mm;
1158         pgprot_t prot = vma->vm_page_prot;
1159         pud_t entry;
1160         spinlock_t *ptl;
1161
1162         ptl = pud_lock(mm, pud);
1163         if (!pud_none(*pud)) {
1164                 if (write) {
1165                         if (pud_pfn(*pud) != pfn_t_to_pfn(pfn)) {
1166                                 WARN_ON_ONCE(!is_huge_zero_pud(*pud));
1167                                 goto out_unlock;
1168                         }
1169                         entry = pud_mkyoung(*pud);
1170                         entry = maybe_pud_mkwrite(pud_mkdirty(entry), vma);
1171                         if (pudp_set_access_flags(vma, addr, pud, entry, 1))
1172                                 update_mmu_cache_pud(vma, addr, pud);
1173                 }
1174                 goto out_unlock;
1175         }
1176
1177         entry = pud_mkhuge(pfn_t_pud(pfn, prot));
1178         if (pfn_t_devmap(pfn))
1179                 entry = pud_mkdevmap(entry);
1180         if (write) {
1181                 entry = pud_mkyoung(pud_mkdirty(entry));
1182                 entry = maybe_pud_mkwrite(entry, vma);
1183         }
1184         set_pud_at(mm, addr, pud, entry);
1185         update_mmu_cache_pud(vma, addr, pud);
1186
1187 out_unlock:
1188         spin_unlock(ptl);
1189 }
1190
1191 /**
1192  * vmf_insert_pfn_pud - insert a pud size pfn
1193  * @vmf: Structure describing the fault
1194  * @pfn: pfn to insert
1195  * @write: whether it's a write fault
1196  *
1197  * Insert a pud size pfn. See vmf_insert_pfn() for additional info.
1198  *
1199  * Return: vm_fault_t value.
1200  */
1201 vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
1202 {
1203         unsigned long addr = vmf->address & PUD_MASK;
1204         struct vm_area_struct *vma = vmf->vma;
1205         pgprot_t pgprot = vma->vm_page_prot;
1206
1207         /*
1208          * If we had pud_special, we could avoid all these restrictions,
1209          * but we need to be consistent with PTEs and architectures that
1210          * can't support a 'special' bit.
1211          */
1212         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
1213                         !pfn_t_devmap(pfn));
1214         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1215                                                 (VM_PFNMAP|VM_MIXEDMAP));
1216         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1217
1218         if (addr < vma->vm_start || addr >= vma->vm_end)
1219                 return VM_FAULT_SIGBUS;
1220
1221         track_pfn_insert(vma, &pgprot, pfn);
1222
1223         insert_pfn_pud(vma, addr, vmf->pud, pfn, write);
1224         return VM_FAULT_NOPAGE;
1225 }
1226 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);
1227 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1228
1229 static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
1230                       pmd_t *pmd, bool write)
1231 {
1232         pmd_t _pmd;
1233
1234         _pmd = pmd_mkyoung(*pmd);
1235         if (write)
1236                 _pmd = pmd_mkdirty(_pmd);
1237         if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
1238                                   pmd, _pmd, write))
1239                 update_mmu_cache_pmd(vma, addr, pmd);
1240 }
1241
1242 struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
1243                 pmd_t *pmd, int flags, struct dev_pagemap **pgmap)
1244 {
1245         unsigned long pfn = pmd_pfn(*pmd);
1246         struct mm_struct *mm = vma->vm_mm;
1247         struct page *page;
1248         int ret;
1249
1250         assert_spin_locked(pmd_lockptr(mm, pmd));
1251
1252         if (flags & FOLL_WRITE && !pmd_write(*pmd))
1253                 return NULL;
1254
1255         if (pmd_present(*pmd) && pmd_devmap(*pmd))
1256                 /* pass */;
1257         else
1258                 return NULL;
1259
1260         if (flags & FOLL_TOUCH)
1261                 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE);
1262
1263         /*
1264          * device mapped pages can only be returned if the
1265          * caller will manage the page reference count.
1266          */
1267         if (!(flags & (FOLL_GET | FOLL_PIN)))
1268                 return ERR_PTR(-EEXIST);
1269
1270         pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
1271         *pgmap = get_dev_pagemap(pfn, *pgmap);
1272         if (!*pgmap)
1273                 return ERR_PTR(-EFAULT);
1274         page = pfn_to_page(pfn);
1275         ret = try_grab_page(page, flags);
1276         if (ret)
1277                 page = ERR_PTR(ret);
1278
1279         return page;
1280 }
1281
1282 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1283                   pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1284                   struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1285 {
1286         spinlock_t *dst_ptl, *src_ptl;
1287         struct page *src_page;
1288         struct folio *src_folio;
1289         pmd_t pmd;
1290         pgtable_t pgtable = NULL;
1291         int ret = -ENOMEM;
1292
1293         /* Skip if can be re-fill on fault */
1294         if (!vma_is_anonymous(dst_vma))
1295                 return 0;
1296
1297         pgtable = pte_alloc_one(dst_mm);
1298         if (unlikely(!pgtable))
1299                 goto out;
1300
1301         dst_ptl = pmd_lock(dst_mm, dst_pmd);
1302         src_ptl = pmd_lockptr(src_mm, src_pmd);
1303         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1304
1305         ret = -EAGAIN;
1306         pmd = *src_pmd;
1307
1308 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
1309         if (unlikely(is_swap_pmd(pmd))) {
1310                 swp_entry_t entry = pmd_to_swp_entry(pmd);
1311
1312                 VM_BUG_ON(!is_pmd_migration_entry(pmd));
1313                 if (!is_readable_migration_entry(entry)) {
1314                         entry = make_readable_migration_entry(
1315                                                         swp_offset(entry));
1316                         pmd = swp_entry_to_pmd(entry);
1317                         if (pmd_swp_soft_dirty(*src_pmd))
1318                                 pmd = pmd_swp_mksoft_dirty(pmd);
1319                         if (pmd_swp_uffd_wp(*src_pmd))
1320                                 pmd = pmd_swp_mkuffd_wp(pmd);
1321                         set_pmd_at(src_mm, addr, src_pmd, pmd);
1322                 }
1323                 add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1324                 mm_inc_nr_ptes(dst_mm);
1325                 pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1326                 if (!userfaultfd_wp(dst_vma))
1327                         pmd = pmd_swp_clear_uffd_wp(pmd);
1328                 set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1329                 ret = 0;
1330                 goto out_unlock;
1331         }
1332 #endif
1333
1334         if (unlikely(!pmd_trans_huge(pmd))) {
1335                 pte_free(dst_mm, pgtable);
1336                 goto out_unlock;
1337         }
1338         /*
1339          * When page table lock is held, the huge zero pmd should not be
1340          * under splitting since we don't split the page itself, only pmd to
1341          * a page table.
1342          */
1343         if (is_huge_zero_pmd(pmd)) {
1344                 /*
1345                  * get_huge_zero_page() will never allocate a new page here,
1346                  * since we already have a zero page to copy. It just takes a
1347                  * reference.
1348                  */
1349                 mm_get_huge_zero_page(dst_mm);
1350                 goto out_zero_page;
1351         }
1352
1353         src_page = pmd_page(pmd);
1354         VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
1355         src_folio = page_folio(src_page);
1356
1357         folio_get(src_folio);
1358         if (unlikely(folio_try_dup_anon_rmap_pmd(src_folio, src_page, src_vma))) {
1359                 /* Page maybe pinned: split and retry the fault on PTEs. */
1360                 folio_put(src_folio);
1361                 pte_free(dst_mm, pgtable);
1362                 spin_unlock(src_ptl);
1363                 spin_unlock(dst_ptl);
1364                 __split_huge_pmd(src_vma, src_pmd, addr, false, NULL);
1365                 return -EAGAIN;
1366         }
1367         add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
1368 out_zero_page:
1369         mm_inc_nr_ptes(dst_mm);
1370         pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
1371         pmdp_set_wrprotect(src_mm, addr, src_pmd);
1372         if (!userfaultfd_wp(dst_vma))
1373                 pmd = pmd_clear_uffd_wp(pmd);
1374         pmd = pmd_mkold(pmd_wrprotect(pmd));
1375         set_pmd_at(dst_mm, addr, dst_pmd, pmd);
1376
1377         ret = 0;
1378 out_unlock:
1379         spin_unlock(src_ptl);
1380         spin_unlock(dst_ptl);
1381 out:
1382         return ret;
1383 }
1384
1385 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1386 static void touch_pud(struct vm_area_struct *vma, unsigned long addr,
1387                       pud_t *pud, bool write)
1388 {
1389         pud_t _pud;
1390
1391         _pud = pud_mkyoung(*pud);
1392         if (write)
1393                 _pud = pud_mkdirty(_pud);
1394         if (pudp_set_access_flags(vma, addr & HPAGE_PUD_MASK,
1395                                   pud, _pud, write))
1396                 update_mmu_cache_pud(vma, addr, pud);
1397 }
1398
1399 struct page *follow_devmap_pud(struct vm_area_struct *vma, unsigned long addr,
1400                 pud_t *pud, int flags, struct dev_pagemap **pgmap)
1401 {
1402         unsigned long pfn = pud_pfn(*pud);
1403         struct mm_struct *mm = vma->vm_mm;
1404         struct page *page;
1405         int ret;
1406
1407         assert_spin_locked(pud_lockptr(mm, pud));
1408
1409         if (flags & FOLL_WRITE && !pud_write(*pud))
1410                 return NULL;
1411
1412         if (pud_present(*pud) && pud_devmap(*pud))
1413                 /* pass */;
1414         else
1415                 return NULL;
1416
1417         if (flags & FOLL_TOUCH)
1418                 touch_pud(vma, addr, pud, flags & FOLL_WRITE);
1419
1420         /*
1421          * device mapped pages can only be returned if the
1422          * caller will manage the page reference count.
1423          *
1424          * At least one of FOLL_GET | FOLL_PIN must be set, so assert that here:
1425          */
1426         if (!(flags & (FOLL_GET | FOLL_PIN)))
1427                 return ERR_PTR(-EEXIST);
1428
1429         pfn += (addr & ~PUD_MASK) >> PAGE_SHIFT;
1430         *pgmap = get_dev_pagemap(pfn, *pgmap);
1431         if (!*pgmap)
1432                 return ERR_PTR(-EFAULT);
1433         page = pfn_to_page(pfn);
1434
1435         ret = try_grab_page(page, flags);
1436         if (ret)
1437                 page = ERR_PTR(ret);
1438
1439         return page;
1440 }
1441
1442 int copy_huge_pud(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1443                   pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1444                   struct vm_area_struct *vma)
1445 {
1446         spinlock_t *dst_ptl, *src_ptl;
1447         pud_t pud;
1448         int ret;
1449
1450         dst_ptl = pud_lock(dst_mm, dst_pud);
1451         src_ptl = pud_lockptr(src_mm, src_pud);
1452         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1453
1454         ret = -EAGAIN;
1455         pud = *src_pud;
1456         if (unlikely(!pud_trans_huge(pud) && !pud_devmap(pud)))
1457                 goto out_unlock;
1458
1459         /*
1460          * When page table lock is held, the huge zero pud should not be
1461          * under splitting since we don't split the page itself, only pud to
1462          * a page table.
1463          */
1464         if (is_huge_zero_pud(pud)) {
1465                 /* No huge zero pud yet */
1466         }
1467
1468         /*
1469          * TODO: once we support anonymous pages, use
1470          * folio_try_dup_anon_rmap_*() and split if duplicating fails.
1471          */
1472         pudp_set_wrprotect(src_mm, addr, src_pud);
1473         pud = pud_mkold(pud_wrprotect(pud));
1474         set_pud_at(dst_mm, addr, dst_pud, pud);
1475
1476         ret = 0;
1477 out_unlock:
1478         spin_unlock(src_ptl);
1479         spin_unlock(dst_ptl);
1480         return ret;
1481 }
1482
1483 void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
1484 {
1485         bool write = vmf->flags & FAULT_FLAG_WRITE;
1486
1487         vmf->ptl = pud_lock(vmf->vma->vm_mm, vmf->pud);
1488         if (unlikely(!pud_same(*vmf->pud, orig_pud)))
1489                 goto unlock;
1490
1491         touch_pud(vmf->vma, vmf->address, vmf->pud, write);
1492 unlock:
1493         spin_unlock(vmf->ptl);
1494 }
1495 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
1496
1497 void huge_pmd_set_accessed(struct vm_fault *vmf)
1498 {
1499         bool write = vmf->flags & FAULT_FLAG_WRITE;
1500
1501         vmf->ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
1502         if (unlikely(!pmd_same(*vmf->pmd, vmf->orig_pmd)))
1503                 goto unlock;
1504
1505         touch_pmd(vmf->vma, vmf->address, vmf->pmd, write);
1506
1507 unlock:
1508         spin_unlock(vmf->ptl);
1509 }
1510
1511 vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf)
1512 {
1513         const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
1514         struct vm_area_struct *vma = vmf->vma;
1515         struct folio *folio;
1516         struct page *page;
1517         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1518         pmd_t orig_pmd = vmf->orig_pmd;
1519
1520         vmf->ptl = pmd_lockptr(vma->vm_mm, vmf->pmd);
1521         VM_BUG_ON_VMA(!vma->anon_vma, vma);
1522
1523         if (is_huge_zero_pmd(orig_pmd))
1524                 goto fallback;
1525
1526         spin_lock(vmf->ptl);
1527
1528         if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1529                 spin_unlock(vmf->ptl);
1530                 return 0;
1531         }
1532
1533         page = pmd_page(orig_pmd);
1534         folio = page_folio(page);
1535         VM_BUG_ON_PAGE(!PageHead(page), page);
1536
1537         /* Early check when only holding the PT lock. */
1538         if (PageAnonExclusive(page))
1539                 goto reuse;
1540
1541         if (!folio_trylock(folio)) {
1542                 folio_get(folio);
1543                 spin_unlock(vmf->ptl);
1544                 folio_lock(folio);
1545                 spin_lock(vmf->ptl);
1546                 if (unlikely(!pmd_same(*vmf->pmd, orig_pmd))) {
1547                         spin_unlock(vmf->ptl);
1548                         folio_unlock(folio);
1549                         folio_put(folio);
1550                         return 0;
1551                 }
1552                 folio_put(folio);
1553         }
1554
1555         /* Recheck after temporarily dropping the PT lock. */
1556         if (PageAnonExclusive(page)) {
1557                 folio_unlock(folio);
1558                 goto reuse;
1559         }
1560
1561         /*
1562          * See do_wp_page(): we can only reuse the folio exclusively if
1563          * there are no additional references. Note that we always drain
1564          * the LRU cache immediately after adding a THP.
1565          */
1566         if (folio_ref_count(folio) >
1567                         1 + folio_test_swapcache(folio) * folio_nr_pages(folio))
1568                 goto unlock_fallback;
1569         if (folio_test_swapcache(folio))
1570                 folio_free_swap(folio);
1571         if (folio_ref_count(folio) == 1) {
1572                 pmd_t entry;
1573
1574                 folio_move_anon_rmap(folio, vma);
1575                 SetPageAnonExclusive(page);
1576                 folio_unlock(folio);
1577 reuse:
1578                 if (unlikely(unshare)) {
1579                         spin_unlock(vmf->ptl);
1580                         return 0;
1581                 }
1582                 entry = pmd_mkyoung(orig_pmd);
1583                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
1584                 if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
1585                         update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1586                 spin_unlock(vmf->ptl);
1587                 return 0;
1588         }
1589
1590 unlock_fallback:
1591         folio_unlock(folio);
1592         spin_unlock(vmf->ptl);
1593 fallback:
1594         __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
1595         return VM_FAULT_FALLBACK;
1596 }
1597
1598 static inline bool can_change_pmd_writable(struct vm_area_struct *vma,
1599                                            unsigned long addr, pmd_t pmd)
1600 {
1601         struct page *page;
1602
1603         if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
1604                 return false;
1605
1606         /* Don't touch entries that are not even readable (NUMA hinting). */
1607         if (pmd_protnone(pmd))
1608                 return false;
1609
1610         /* Do we need write faults for softdirty tracking? */
1611         if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd))
1612                 return false;
1613
1614         /* Do we need write faults for uffd-wp tracking? */
1615         if (userfaultfd_huge_pmd_wp(vma, pmd))
1616                 return false;
1617
1618         if (!(vma->vm_flags & VM_SHARED)) {
1619                 /* See can_change_pte_writable(). */
1620                 page = vm_normal_page_pmd(vma, addr, pmd);
1621                 return page && PageAnon(page) && PageAnonExclusive(page);
1622         }
1623
1624         /* See can_change_pte_writable(). */
1625         return pmd_dirty(pmd);
1626 }
1627
1628 /* FOLL_FORCE can write to even unwritable PMDs in COW mappings. */
1629 static inline bool can_follow_write_pmd(pmd_t pmd, struct page *page,
1630                                         struct vm_area_struct *vma,
1631                                         unsigned int flags)
1632 {
1633         /* If the pmd is writable, we can write to the page. */
1634         if (pmd_write(pmd))
1635                 return true;
1636
1637         /* Maybe FOLL_FORCE is set to override it? */
1638         if (!(flags & FOLL_FORCE))
1639                 return false;
1640
1641         /* But FOLL_FORCE has no effect on shared mappings */
1642         if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED))
1643                 return false;
1644
1645         /* ... or read-only private ones */
1646         if (!(vma->vm_flags & VM_MAYWRITE))
1647                 return false;
1648
1649         /* ... or already writable ones that just need to take a write fault */
1650         if (vma->vm_flags & VM_WRITE)
1651                 return false;
1652
1653         /*
1654          * See can_change_pte_writable(): we broke COW and could map the page
1655          * writable if we have an exclusive anonymous page ...
1656          */
1657         if (!page || !PageAnon(page) || !PageAnonExclusive(page))
1658                 return false;
1659
1660         /* ... and a write-fault isn't required for other reasons. */
1661         if (vma_soft_dirty_enabled(vma) && !pmd_soft_dirty(pmd))
1662                 return false;
1663         return !userfaultfd_huge_pmd_wp(vma, pmd);
1664 }
1665
1666 struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
1667                                    unsigned long addr,
1668                                    pmd_t *pmd,
1669                                    unsigned int flags)
1670 {
1671         struct mm_struct *mm = vma->vm_mm;
1672         struct page *page;
1673         int ret;
1674
1675         assert_spin_locked(pmd_lockptr(mm, pmd));
1676
1677         page = pmd_page(*pmd);
1678         VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
1679
1680         if ((flags & FOLL_WRITE) &&
1681             !can_follow_write_pmd(*pmd, page, vma, flags))
1682                 return NULL;
1683
1684         /* Avoid dumping huge zero page */
1685         if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
1686                 return ERR_PTR(-EFAULT);
1687
1688         if (pmd_protnone(*pmd) && !gup_can_follow_protnone(vma, flags))
1689                 return NULL;
1690
1691         if (!pmd_write(*pmd) && gup_must_unshare(vma, flags, page))
1692                 return ERR_PTR(-EMLINK);
1693
1694         VM_BUG_ON_PAGE((flags & FOLL_PIN) && PageAnon(page) &&
1695                         !PageAnonExclusive(page), page);
1696
1697         ret = try_grab_page(page, flags);
1698         if (ret)
1699                 return ERR_PTR(ret);
1700
1701         if (flags & FOLL_TOUCH)
1702                 touch_pmd(vma, addr, pmd, flags & FOLL_WRITE);
1703
1704         page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
1705         VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
1706
1707         return page;
1708 }
1709
1710 /* NUMA hinting page fault entry point for trans huge pmds */
1711 vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
1712 {
1713         struct vm_area_struct *vma = vmf->vma;
1714         pmd_t oldpmd = vmf->orig_pmd;
1715         pmd_t pmd;
1716         struct folio *folio;
1717         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
1718         int nid = NUMA_NO_NODE;
1719         int target_nid, last_cpupid = (-1 & LAST_CPUPID_MASK);
1720         bool migrated = false, writable = false;
1721         int flags = 0;
1722
1723         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1724         if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
1725                 spin_unlock(vmf->ptl);
1726                 goto out;
1727         }
1728
1729         pmd = pmd_modify(oldpmd, vma->vm_page_prot);
1730
1731         /*
1732          * Detect now whether the PMD could be writable; this information
1733          * is only valid while holding the PT lock.
1734          */
1735         writable = pmd_write(pmd);
1736         if (!writable && vma_wants_manual_pte_write_upgrade(vma) &&
1737             can_change_pmd_writable(vma, vmf->address, pmd))
1738                 writable = true;
1739
1740         folio = vm_normal_folio_pmd(vma, haddr, pmd);
1741         if (!folio)
1742                 goto out_map;
1743
1744         /* See similar comment in do_numa_page for explanation */
1745         if (!writable)
1746                 flags |= TNF_NO_GROUP;
1747
1748         nid = folio_nid(folio);
1749         /*
1750          * For memory tiering mode, cpupid of slow memory page is used
1751          * to record page access time.  So use default value.
1752          */
1753         if (node_is_toptier(nid))
1754                 last_cpupid = folio_last_cpupid(folio);
1755         target_nid = numa_migrate_prep(folio, vma, haddr, nid, &flags);
1756         if (target_nid == NUMA_NO_NODE) {
1757                 folio_put(folio);
1758                 goto out_map;
1759         }
1760
1761         spin_unlock(vmf->ptl);
1762         writable = false;
1763
1764         migrated = migrate_misplaced_folio(folio, vma, target_nid);
1765         if (migrated) {
1766                 flags |= TNF_MIGRATED;
1767                 nid = target_nid;
1768         } else {
1769                 flags |= TNF_MIGRATE_FAIL;
1770                 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
1771                 if (unlikely(!pmd_same(oldpmd, *vmf->pmd))) {
1772                         spin_unlock(vmf->ptl);
1773                         goto out;
1774                 }
1775                 goto out_map;
1776         }
1777
1778 out:
1779         if (nid != NUMA_NO_NODE)
1780                 task_numa_fault(last_cpupid, nid, HPAGE_PMD_NR, flags);
1781
1782         return 0;
1783
1784 out_map:
1785         /* Restore the PMD */
1786         pmd = pmd_modify(oldpmd, vma->vm_page_prot);
1787         pmd = pmd_mkyoung(pmd);
1788         if (writable)
1789                 pmd = pmd_mkwrite(pmd, vma);
1790         set_pmd_at(vma->vm_mm, haddr, vmf->pmd, pmd);
1791         update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
1792         spin_unlock(vmf->ptl);
1793         goto out;
1794 }
1795
1796 /*
1797  * Return true if we do MADV_FREE successfully on entire pmd page.
1798  * Otherwise, return false.
1799  */
1800 bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1801                 pmd_t *pmd, unsigned long addr, unsigned long next)
1802 {
1803         spinlock_t *ptl;
1804         pmd_t orig_pmd;
1805         struct folio *folio;
1806         struct mm_struct *mm = tlb->mm;
1807         bool ret = false;
1808
1809         tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1810
1811         ptl = pmd_trans_huge_lock(pmd, vma);
1812         if (!ptl)
1813                 goto out_unlocked;
1814
1815         orig_pmd = *pmd;
1816         if (is_huge_zero_pmd(orig_pmd))
1817                 goto out;
1818
1819         if (unlikely(!pmd_present(orig_pmd))) {
1820                 VM_BUG_ON(thp_migration_supported() &&
1821                                   !is_pmd_migration_entry(orig_pmd));
1822                 goto out;
1823         }
1824
1825         folio = pfn_folio(pmd_pfn(orig_pmd));
1826         /*
1827          * If other processes are mapping this folio, we couldn't discard
1828          * the folio unless they all do MADV_FREE so let's skip the folio.
1829          */
1830         if (folio_estimated_sharers(folio) != 1)
1831                 goto out;
1832
1833         if (!folio_trylock(folio))
1834                 goto out;
1835
1836         /*
1837          * If user want to discard part-pages of THP, split it so MADV_FREE
1838          * will deactivate only them.
1839          */
1840         if (next - addr != HPAGE_PMD_SIZE) {
1841                 folio_get(folio);
1842                 spin_unlock(ptl);
1843                 split_folio(folio);
1844                 folio_unlock(folio);
1845                 folio_put(folio);
1846                 goto out_unlocked;
1847         }
1848
1849         if (folio_test_dirty(folio))
1850                 folio_clear_dirty(folio);
1851         folio_unlock(folio);
1852
1853         if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
1854                 pmdp_invalidate(vma, addr, pmd);
1855                 orig_pmd = pmd_mkold(orig_pmd);
1856                 orig_pmd = pmd_mkclean(orig_pmd);
1857
1858                 set_pmd_at(mm, addr, pmd, orig_pmd);
1859                 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1860         }
1861
1862         folio_mark_lazyfree(folio);
1863         ret = true;
1864 out:
1865         spin_unlock(ptl);
1866 out_unlocked:
1867         return ret;
1868 }
1869
1870 static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
1871 {
1872         pgtable_t pgtable;
1873
1874         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
1875         pte_free(mm, pgtable);
1876         mm_dec_nr_ptes(mm);
1877 }
1878
1879 int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
1880                  pmd_t *pmd, unsigned long addr)
1881 {
1882         pmd_t orig_pmd;
1883         spinlock_t *ptl;
1884
1885         tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
1886
1887         ptl = __pmd_trans_huge_lock(pmd, vma);
1888         if (!ptl)
1889                 return 0;
1890         /*
1891          * For architectures like ppc64 we look at deposited pgtable
1892          * when calling pmdp_huge_get_and_clear. So do the
1893          * pgtable_trans_huge_withdraw after finishing pmdp related
1894          * operations.
1895          */
1896         orig_pmd = pmdp_huge_get_and_clear_full(vma, addr, pmd,
1897                                                 tlb->fullmm);
1898         arch_check_zapped_pmd(vma, orig_pmd);
1899         tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
1900         if (vma_is_special_huge(vma)) {
1901                 if (arch_needs_pgtable_deposit())
1902                         zap_deposited_table(tlb->mm, pmd);
1903                 spin_unlock(ptl);
1904         } else if (is_huge_zero_pmd(orig_pmd)) {
1905                 zap_deposited_table(tlb->mm, pmd);
1906                 spin_unlock(ptl);
1907         } else {
1908                 struct page *page = NULL;
1909                 int flush_needed = 1;
1910
1911                 if (pmd_present(orig_pmd)) {
1912                         page = pmd_page(orig_pmd);
1913                         folio_remove_rmap_pmd(page_folio(page), page, vma);
1914                         VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
1915                         VM_BUG_ON_PAGE(!PageHead(page), page);
1916                 } else if (thp_migration_supported()) {
1917                         swp_entry_t entry;
1918
1919                         VM_BUG_ON(!is_pmd_migration_entry(orig_pmd));
1920                         entry = pmd_to_swp_entry(orig_pmd);
1921                         page = pfn_swap_entry_to_page(entry);
1922                         flush_needed = 0;
1923                 } else
1924                         WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
1925
1926                 if (PageAnon(page)) {
1927                         zap_deposited_table(tlb->mm, pmd);
1928                         add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
1929                 } else {
1930                         if (arch_needs_pgtable_deposit())
1931                                 zap_deposited_table(tlb->mm, pmd);
1932                         add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR);
1933                 }
1934
1935                 spin_unlock(ptl);
1936                 if (flush_needed)
1937                         tlb_remove_page_size(tlb, page, HPAGE_PMD_SIZE);
1938         }
1939         return 1;
1940 }
1941
1942 #ifndef pmd_move_must_withdraw
1943 static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
1944                                          spinlock_t *old_pmd_ptl,
1945                                          struct vm_area_struct *vma)
1946 {
1947         /*
1948          * With split pmd lock we also need to move preallocated
1949          * PTE page table if new_pmd is on different PMD page table.
1950          *
1951          * We also don't deposit and withdraw tables for file pages.
1952          */
1953         return (new_pmd_ptl != old_pmd_ptl) && vma_is_anonymous(vma);
1954 }
1955 #endif
1956
1957 static pmd_t move_soft_dirty_pmd(pmd_t pmd)
1958 {
1959 #ifdef CONFIG_MEM_SOFT_DIRTY
1960         if (unlikely(is_pmd_migration_entry(pmd)))
1961                 pmd = pmd_swp_mksoft_dirty(pmd);
1962         else if (pmd_present(pmd))
1963                 pmd = pmd_mksoft_dirty(pmd);
1964 #endif
1965         return pmd;
1966 }
1967
1968 bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
1969                   unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd)
1970 {
1971         spinlock_t *old_ptl, *new_ptl;
1972         pmd_t pmd;
1973         struct mm_struct *mm = vma->vm_mm;
1974         bool force_flush = false;
1975
1976         /*
1977          * The destination pmd shouldn't be established, free_pgtables()
1978          * should have released it; but move_page_tables() might have already
1979          * inserted a page table, if racing against shmem/file collapse.
1980          */
1981         if (!pmd_none(*new_pmd)) {
1982                 VM_BUG_ON(pmd_trans_huge(*new_pmd));
1983                 return false;
1984         }
1985
1986         /*
1987          * We don't have to worry about the ordering of src and dst
1988          * ptlocks because exclusive mmap_lock prevents deadlock.
1989          */
1990         old_ptl = __pmd_trans_huge_lock(old_pmd, vma);
1991         if (old_ptl) {
1992                 new_ptl = pmd_lockptr(mm, new_pmd);
1993                 if (new_ptl != old_ptl)
1994                         spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
1995                 pmd = pmdp_huge_get_and_clear(mm, old_addr, old_pmd);
1996                 if (pmd_present(pmd))
1997                         force_flush = true;
1998                 VM_BUG_ON(!pmd_none(*new_pmd));
1999
2000                 if (pmd_move_must_withdraw(new_ptl, old_ptl, vma)) {
2001                         pgtable_t pgtable;
2002                         pgtable = pgtable_trans_huge_withdraw(mm, old_pmd);
2003                         pgtable_trans_huge_deposit(mm, new_pmd, pgtable);
2004                 }
2005                 pmd = move_soft_dirty_pmd(pmd);
2006                 set_pmd_at(mm, new_addr, new_pmd, pmd);
2007                 if (force_flush)
2008                         flush_pmd_tlb_range(vma, old_addr, old_addr + PMD_SIZE);
2009                 if (new_ptl != old_ptl)
2010                         spin_unlock(new_ptl);
2011                 spin_unlock(old_ptl);
2012                 return true;
2013         }
2014         return false;
2015 }
2016
2017 /*
2018  * Returns
2019  *  - 0 if PMD could not be locked
2020  *  - 1 if PMD was locked but protections unchanged and TLB flush unnecessary
2021  *      or if prot_numa but THP migration is not supported
2022  *  - HPAGE_PMD_NR if protections changed and TLB flush necessary
2023  */
2024 int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
2025                     pmd_t *pmd, unsigned long addr, pgprot_t newprot,
2026                     unsigned long cp_flags)
2027 {
2028         struct mm_struct *mm = vma->vm_mm;
2029         spinlock_t *ptl;
2030         pmd_t oldpmd, entry;
2031         bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
2032         bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
2033         bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
2034         int ret = 1;
2035
2036         tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
2037
2038         if (prot_numa && !thp_migration_supported())
2039                 return 1;
2040
2041         ptl = __pmd_trans_huge_lock(pmd, vma);
2042         if (!ptl)
2043                 return 0;
2044
2045 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
2046         if (is_swap_pmd(*pmd)) {
2047                 swp_entry_t entry = pmd_to_swp_entry(*pmd);
2048                 struct folio *folio = page_folio(pfn_swap_entry_to_page(entry));
2049                 pmd_t newpmd;
2050
2051                 VM_BUG_ON(!is_pmd_migration_entry(*pmd));
2052                 if (is_writable_migration_entry(entry)) {
2053                         /*
2054                          * A protection check is difficult so
2055                          * just be safe and disable write
2056                          */
2057                         if (folio_test_anon(folio))
2058                                 entry = make_readable_exclusive_migration_entry(swp_offset(entry));
2059                         else
2060                                 entry = make_readable_migration_entry(swp_offset(entry));
2061                         newpmd = swp_entry_to_pmd(entry);
2062                         if (pmd_swp_soft_dirty(*pmd))
2063                                 newpmd = pmd_swp_mksoft_dirty(newpmd);
2064                 } else {
2065                         newpmd = *pmd;
2066                 }
2067
2068                 if (uffd_wp)
2069                         newpmd = pmd_swp_mkuffd_wp(newpmd);
2070                 else if (uffd_wp_resolve)
2071                         newpmd = pmd_swp_clear_uffd_wp(newpmd);
2072                 if (!pmd_same(*pmd, newpmd))
2073                         set_pmd_at(mm, addr, pmd, newpmd);
2074                 goto unlock;
2075         }
2076 #endif
2077
2078         if (prot_numa) {
2079                 struct folio *folio;
2080                 bool toptier;
2081                 /*
2082                  * Avoid trapping faults against the zero page. The read-only
2083                  * data is likely to be read-cached on the local CPU and
2084                  * local/remote hits to the zero page are not interesting.
2085                  */
2086                 if (is_huge_zero_pmd(*pmd))
2087                         goto unlock;
2088
2089                 if (pmd_protnone(*pmd))
2090                         goto unlock;
2091
2092                 folio = page_folio(pmd_page(*pmd));
2093                 toptier = node_is_toptier(folio_nid(folio));
2094                 /*
2095                  * Skip scanning top tier node if normal numa
2096                  * balancing is disabled
2097                  */
2098                 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
2099                     toptier)
2100                         goto unlock;
2101
2102                 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
2103                     !toptier)
2104                         folio_xchg_access_time(folio,
2105                                                jiffies_to_msecs(jiffies));
2106         }
2107         /*
2108          * In case prot_numa, we are under mmap_read_lock(mm). It's critical
2109          * to not clear pmd intermittently to avoid race with MADV_DONTNEED
2110          * which is also under mmap_read_lock(mm):
2111          *
2112          *      CPU0:                           CPU1:
2113          *                              change_huge_pmd(prot_numa=1)
2114          *                               pmdp_huge_get_and_clear_notify()
2115          * madvise_dontneed()
2116          *  zap_pmd_range()
2117          *   pmd_trans_huge(*pmd) == 0 (without ptl)
2118          *   // skip the pmd
2119          *                               set_pmd_at();
2120          *                               // pmd is re-established
2121          *
2122          * The race makes MADV_DONTNEED miss the huge pmd and don't clear it
2123          * which may break userspace.
2124          *
2125          * pmdp_invalidate_ad() is required to make sure we don't miss
2126          * dirty/young flags set by hardware.
2127          */
2128         oldpmd = pmdp_invalidate_ad(vma, addr, pmd);
2129
2130         entry = pmd_modify(oldpmd, newprot);
2131         if (uffd_wp)
2132                 entry = pmd_mkuffd_wp(entry);
2133         else if (uffd_wp_resolve)
2134                 /*
2135                  * Leave the write bit to be handled by PF interrupt
2136                  * handler, then things like COW could be properly
2137                  * handled.
2138                  */
2139                 entry = pmd_clear_uffd_wp(entry);
2140
2141         /* See change_pte_range(). */
2142         if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && !pmd_write(entry) &&
2143             can_change_pmd_writable(vma, addr, entry))
2144                 entry = pmd_mkwrite(entry, vma);
2145
2146         ret = HPAGE_PMD_NR;
2147         set_pmd_at(mm, addr, pmd, entry);
2148
2149         if (huge_pmd_needs_flush(oldpmd, entry))
2150                 tlb_flush_pmd_range(tlb, addr, HPAGE_PMD_SIZE);
2151 unlock:
2152         spin_unlock(ptl);
2153         return ret;
2154 }
2155
2156 #ifdef CONFIG_USERFAULTFD
2157 /*
2158  * The PT lock for src_pmd and the mmap_lock for reading are held by
2159  * the caller, but it must return after releasing the page_table_lock.
2160  * Just move the page from src_pmd to dst_pmd if possible.
2161  * Return zero if succeeded in moving the page, -EAGAIN if it needs to be
2162  * repeated by the caller, or other errors in case of failure.
2163  */
2164 int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval,
2165                         struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
2166                         unsigned long dst_addr, unsigned long src_addr)
2167 {
2168         pmd_t _dst_pmd, src_pmdval;
2169         struct page *src_page;
2170         struct folio *src_folio;
2171         struct anon_vma *src_anon_vma;
2172         spinlock_t *src_ptl, *dst_ptl;
2173         pgtable_t src_pgtable;
2174         struct mmu_notifier_range range;
2175         int err = 0;
2176
2177         src_pmdval = *src_pmd;
2178         src_ptl = pmd_lockptr(mm, src_pmd);
2179
2180         lockdep_assert_held(src_ptl);
2181         mmap_assert_locked(mm);
2182
2183         /* Sanity checks before the operation */
2184         if (WARN_ON_ONCE(!pmd_none(dst_pmdval)) || WARN_ON_ONCE(src_addr & ~HPAGE_PMD_MASK) ||
2185             WARN_ON_ONCE(dst_addr & ~HPAGE_PMD_MASK)) {
2186                 spin_unlock(src_ptl);
2187                 return -EINVAL;
2188         }
2189
2190         if (!pmd_trans_huge(src_pmdval)) {
2191                 spin_unlock(src_ptl);
2192                 if (is_pmd_migration_entry(src_pmdval)) {
2193                         pmd_migration_entry_wait(mm, &src_pmdval);
2194                         return -EAGAIN;
2195                 }
2196                 return -ENOENT;
2197         }
2198
2199         src_page = pmd_page(src_pmdval);
2200         if (unlikely(!PageAnonExclusive(src_page))) {
2201                 spin_unlock(src_ptl);
2202                 return -EBUSY;
2203         }
2204
2205         src_folio = page_folio(src_page);
2206         folio_get(src_folio);
2207         spin_unlock(src_ptl);
2208
2209         flush_cache_range(src_vma, src_addr, src_addr + HPAGE_PMD_SIZE);
2210         mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, src_addr,
2211                                 src_addr + HPAGE_PMD_SIZE);
2212         mmu_notifier_invalidate_range_start(&range);
2213
2214         folio_lock(src_folio);
2215
2216         /*
2217          * split_huge_page walks the anon_vma chain without the page
2218          * lock. Serialize against it with the anon_vma lock, the page
2219          * lock is not enough.
2220          */
2221         src_anon_vma = folio_get_anon_vma(src_folio);
2222         if (!src_anon_vma) {
2223                 err = -EAGAIN;
2224                 goto unlock_folio;
2225         }
2226         anon_vma_lock_write(src_anon_vma);
2227
2228         dst_ptl = pmd_lockptr(mm, dst_pmd);
2229         double_pt_lock(src_ptl, dst_ptl);
2230         if (unlikely(!pmd_same(*src_pmd, src_pmdval) ||
2231                      !pmd_same(*dst_pmd, dst_pmdval))) {
2232                 err = -EAGAIN;
2233                 goto unlock_ptls;
2234         }
2235         if (folio_maybe_dma_pinned(src_folio) ||
2236             !PageAnonExclusive(&src_folio->page)) {
2237                 err = -EBUSY;
2238                 goto unlock_ptls;
2239         }
2240
2241         if (WARN_ON_ONCE(!folio_test_head(src_folio)) ||
2242             WARN_ON_ONCE(!folio_test_anon(src_folio))) {
2243                 err = -EBUSY;
2244                 goto unlock_ptls;
2245         }
2246
2247         src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd);
2248         /* Folio got pinned from under us. Put it back and fail the move. */
2249         if (folio_maybe_dma_pinned(src_folio)) {
2250                 set_pmd_at(mm, src_addr, src_pmd, src_pmdval);
2251                 err = -EBUSY;
2252                 goto unlock_ptls;
2253         }
2254
2255         folio_move_anon_rmap(src_folio, dst_vma);
2256         WRITE_ONCE(src_folio->index, linear_page_index(dst_vma, dst_addr));
2257
2258         _dst_pmd = mk_huge_pmd(&src_folio->page, dst_vma->vm_page_prot);
2259         /* Follow mremap() behavior and treat the entry dirty after the move */
2260         _dst_pmd = pmd_mkwrite(pmd_mkdirty(_dst_pmd), dst_vma);
2261         set_pmd_at(mm, dst_addr, dst_pmd, _dst_pmd);
2262
2263         src_pgtable = pgtable_trans_huge_withdraw(mm, src_pmd);
2264         pgtable_trans_huge_deposit(mm, dst_pmd, src_pgtable);
2265 unlock_ptls:
2266         double_pt_unlock(src_ptl, dst_ptl);
2267         anon_vma_unlock_write(src_anon_vma);
2268         put_anon_vma(src_anon_vma);
2269 unlock_folio:
2270         /* unblock rmap walks */
2271         folio_unlock(src_folio);
2272         mmu_notifier_invalidate_range_end(&range);
2273         folio_put(src_folio);
2274         return err;
2275 }
2276 #endif /* CONFIG_USERFAULTFD */
2277
2278 /*
2279  * Returns page table lock pointer if a given pmd maps a thp, NULL otherwise.
2280  *
2281  * Note that if it returns page table lock pointer, this routine returns without
2282  * unlocking page table lock. So callers must unlock it.
2283  */
2284 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma)
2285 {
2286         spinlock_t *ptl;
2287         ptl = pmd_lock(vma->vm_mm, pmd);
2288         if (likely(is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) ||
2289                         pmd_devmap(*pmd)))
2290                 return ptl;
2291         spin_unlock(ptl);
2292         return NULL;
2293 }
2294
2295 /*
2296  * Returns page table lock pointer if a given pud maps a thp, NULL otherwise.
2297  *
2298  * Note that if it returns page table lock pointer, this routine returns without
2299  * unlocking page table lock. So callers must unlock it.
2300  */
2301 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma)
2302 {
2303         spinlock_t *ptl;
2304
2305         ptl = pud_lock(vma->vm_mm, pud);
2306         if (likely(pud_trans_huge(*pud) || pud_devmap(*pud)))
2307                 return ptl;
2308         spin_unlock(ptl);
2309         return NULL;
2310 }
2311
2312 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
2313 int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma,
2314                  pud_t *pud, unsigned long addr)
2315 {
2316         spinlock_t *ptl;
2317
2318         ptl = __pud_trans_huge_lock(pud, vma);
2319         if (!ptl)
2320                 return 0;
2321
2322         pudp_huge_get_and_clear_full(vma, addr, pud, tlb->fullmm);
2323         tlb_remove_pud_tlb_entry(tlb, pud, addr);
2324         if (vma_is_special_huge(vma)) {
2325                 spin_unlock(ptl);
2326                 /* No zero page support yet */
2327         } else {
2328                 /* No support for anonymous PUD pages yet */
2329                 BUG();
2330         }
2331         return 1;
2332 }
2333
2334 static void __split_huge_pud_locked(struct vm_area_struct *vma, pud_t *pud,
2335                 unsigned long haddr)
2336 {
2337         VM_BUG_ON(haddr & ~HPAGE_PUD_MASK);
2338         VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2339         VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PUD_SIZE, vma);
2340         VM_BUG_ON(!pud_trans_huge(*pud) && !pud_devmap(*pud));
2341
2342         count_vm_event(THP_SPLIT_PUD);
2343
2344         pudp_huge_clear_flush(vma, haddr, pud);
2345 }
2346
2347 void __split_huge_pud(struct vm_area_struct *vma, pud_t *pud,
2348                 unsigned long address)
2349 {
2350         spinlock_t *ptl;
2351         struct mmu_notifier_range range;
2352
2353         mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
2354                                 address & HPAGE_PUD_MASK,
2355                                 (address & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE);
2356         mmu_notifier_invalidate_range_start(&range);
2357         ptl = pud_lock(vma->vm_mm, pud);
2358         if (unlikely(!pud_trans_huge(*pud) && !pud_devmap(*pud)))
2359                 goto out;
2360         __split_huge_pud_locked(vma, pud, range.start);
2361
2362 out:
2363         spin_unlock(ptl);
2364         mmu_notifier_invalidate_range_end(&range);
2365 }
2366 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
2367
2368 static void __split_huge_zero_page_pmd(struct vm_area_struct *vma,
2369                 unsigned long haddr, pmd_t *pmd)
2370 {
2371         struct mm_struct *mm = vma->vm_mm;
2372         pgtable_t pgtable;
2373         pmd_t _pmd, old_pmd;
2374         unsigned long addr;
2375         pte_t *pte;
2376         int i;
2377
2378         /*
2379          * Leave pmd empty until pte is filled note that it is fine to delay
2380          * notification until mmu_notifier_invalidate_range_end() as we are
2381          * replacing a zero pmd write protected page with a zero pte write
2382          * protected page.
2383          *
2384          * See Documentation/mm/mmu_notifier.rst
2385          */
2386         old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd);
2387
2388         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2389         pmd_populate(mm, &_pmd, pgtable);
2390
2391         pte = pte_offset_map(&_pmd, haddr);
2392         VM_BUG_ON(!pte);
2393         for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2394                 pte_t entry;
2395
2396                 entry = pfn_pte(my_zero_pfn(addr), vma->vm_page_prot);
2397                 entry = pte_mkspecial(entry);
2398                 if (pmd_uffd_wp(old_pmd))
2399                         entry = pte_mkuffd_wp(entry);
2400                 VM_BUG_ON(!pte_none(ptep_get(pte)));
2401                 set_pte_at(mm, addr, pte, entry);
2402                 pte++;
2403         }
2404         pte_unmap(pte - 1);
2405         smp_wmb(); /* make pte visible before pmd */
2406         pmd_populate(mm, pmd, pgtable);
2407 }
2408
2409 static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
2410                 unsigned long haddr, bool freeze)
2411 {
2412         struct mm_struct *mm = vma->vm_mm;
2413         struct folio *folio;
2414         struct page *page;
2415         pgtable_t pgtable;
2416         pmd_t old_pmd, _pmd;
2417         bool young, write, soft_dirty, pmd_migration = false, uffd_wp = false;
2418         bool anon_exclusive = false, dirty = false;
2419         unsigned long addr;
2420         pte_t *pte;
2421         int i;
2422
2423         VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
2424         VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
2425         VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
2426         VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd)
2427                                 && !pmd_devmap(*pmd));
2428
2429         count_vm_event(THP_SPLIT_PMD);
2430
2431         if (!vma_is_anonymous(vma)) {
2432                 old_pmd = pmdp_huge_clear_flush(vma, haddr, pmd);
2433                 /*
2434                  * We are going to unmap this huge page. So
2435                  * just go ahead and zap it
2436                  */
2437                 if (arch_needs_pgtable_deposit())
2438                         zap_deposited_table(mm, pmd);
2439                 if (vma_is_special_huge(vma))
2440                         return;
2441                 if (unlikely(is_pmd_migration_entry(old_pmd))) {
2442                         swp_entry_t entry;
2443
2444                         entry = pmd_to_swp_entry(old_pmd);
2445                         page = pfn_swap_entry_to_page(entry);
2446                 } else {
2447                         page = pmd_page(old_pmd);
2448                         folio = page_folio(page);
2449                         if (!folio_test_dirty(folio) && pmd_dirty(old_pmd))
2450                                 folio_mark_dirty(folio);
2451                         if (!folio_test_referenced(folio) && pmd_young(old_pmd))
2452                                 folio_set_referenced(folio);
2453                         folio_remove_rmap_pmd(folio, page, vma);
2454                         folio_put(folio);
2455                 }
2456                 add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR);
2457                 return;
2458         }
2459
2460         if (is_huge_zero_pmd(*pmd)) {
2461                 /*
2462                  * FIXME: Do we want to invalidate secondary mmu by calling
2463                  * mmu_notifier_arch_invalidate_secondary_tlbs() see comments below
2464                  * inside __split_huge_pmd() ?
2465                  *
2466                  * We are going from a zero huge page write protected to zero
2467                  * small page also write protected so it does not seems useful
2468                  * to invalidate secondary mmu at this time.
2469                  */
2470                 return __split_huge_zero_page_pmd(vma, haddr, pmd);
2471         }
2472
2473         /*
2474          * Up to this point the pmd is present and huge and userland has the
2475          * whole access to the hugepage during the split (which happens in
2476          * place). If we overwrite the pmd with the not-huge version pointing
2477          * to the pte here (which of course we could if all CPUs were bug
2478          * free), userland could trigger a small page size TLB miss on the
2479          * small sized TLB while the hugepage TLB entry is still established in
2480          * the huge TLB. Some CPU doesn't like that.
2481          * See http://support.amd.com/TechDocs/41322_10h_Rev_Gd.pdf, Erratum
2482          * 383 on page 105. Intel should be safe but is also warns that it's
2483          * only safe if the permission and cache attributes of the two entries
2484          * loaded in the two TLB is identical (which should be the case here).
2485          * But it is generally safer to never allow small and huge TLB entries
2486          * for the same virtual address to be loaded simultaneously. So instead
2487          * of doing "pmd_populate(); flush_pmd_tlb_range();" we first mark the
2488          * current pmd notpresent (atomically because here the pmd_trans_huge
2489          * must remain set at all times on the pmd until the split is complete
2490          * for this pmd), then we flush the SMP TLB and finally we write the
2491          * non-huge version of the pmd entry with pmd_populate.
2492          */
2493         old_pmd = pmdp_invalidate(vma, haddr, pmd);
2494
2495         pmd_migration = is_pmd_migration_entry(old_pmd);
2496         if (unlikely(pmd_migration)) {
2497                 swp_entry_t entry;
2498
2499                 entry = pmd_to_swp_entry(old_pmd);
2500                 page = pfn_swap_entry_to_page(entry);
2501                 write = is_writable_migration_entry(entry);
2502                 if (PageAnon(page))
2503                         anon_exclusive = is_readable_exclusive_migration_entry(entry);
2504                 young = is_migration_entry_young(entry);
2505                 dirty = is_migration_entry_dirty(entry);
2506                 soft_dirty = pmd_swp_soft_dirty(old_pmd);
2507                 uffd_wp = pmd_swp_uffd_wp(old_pmd);
2508         } else {
2509                 page = pmd_page(old_pmd);
2510                 folio = page_folio(page);
2511                 if (pmd_dirty(old_pmd)) {
2512                         dirty = true;
2513                         folio_set_dirty(folio);
2514                 }
2515                 write = pmd_write(old_pmd);
2516                 young = pmd_young(old_pmd);
2517                 soft_dirty = pmd_soft_dirty(old_pmd);
2518                 uffd_wp = pmd_uffd_wp(old_pmd);
2519
2520                 VM_WARN_ON_FOLIO(!folio_ref_count(folio), folio);
2521                 VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
2522
2523                 /*
2524                  * Without "freeze", we'll simply split the PMD, propagating the
2525                  * PageAnonExclusive() flag for each PTE by setting it for
2526                  * each subpage -- no need to (temporarily) clear.
2527                  *
2528                  * With "freeze" we want to replace mapped pages by
2529                  * migration entries right away. This is only possible if we
2530                  * managed to clear PageAnonExclusive() -- see
2531                  * set_pmd_migration_entry().
2532                  *
2533                  * In case we cannot clear PageAnonExclusive(), split the PMD
2534                  * only and let try_to_migrate_one() fail later.
2535                  *
2536                  * See folio_try_share_anon_rmap_pmd(): invalidate PMD first.
2537                  */
2538                 anon_exclusive = PageAnonExclusive(page);
2539                 if (freeze && anon_exclusive &&
2540                     folio_try_share_anon_rmap_pmd(folio, page))
2541                         freeze = false;
2542                 if (!freeze) {
2543                         rmap_t rmap_flags = RMAP_NONE;
2544
2545                         folio_ref_add(folio, HPAGE_PMD_NR - 1);
2546                         if (anon_exclusive)
2547                                 rmap_flags |= RMAP_EXCLUSIVE;
2548                         folio_add_anon_rmap_ptes(folio, page, HPAGE_PMD_NR,
2549                                                  vma, haddr, rmap_flags);
2550                 }
2551         }
2552
2553         /*
2554          * Withdraw the table only after we mark the pmd entry invalid.
2555          * This's critical for some architectures (Power).
2556          */
2557         pgtable = pgtable_trans_huge_withdraw(mm, pmd);
2558         pmd_populate(mm, &_pmd, pgtable);
2559
2560         pte = pte_offset_map(&_pmd, haddr);
2561         VM_BUG_ON(!pte);
2562         for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
2563                 pte_t entry;
2564                 /*
2565                  * Note that NUMA hinting access restrictions are not
2566                  * transferred to avoid any possibility of altering
2567                  * permissions across VMAs.
2568                  */
2569                 if (freeze || pmd_migration) {
2570                         swp_entry_t swp_entry;
2571                         if (write)
2572                                 swp_entry = make_writable_migration_entry(
2573                                                         page_to_pfn(page + i));
2574                         else if (anon_exclusive)
2575                                 swp_entry = make_readable_exclusive_migration_entry(
2576                                                         page_to_pfn(page + i));
2577                         else
2578                                 swp_entry = make_readable_migration_entry(
2579                                                         page_to_pfn(page + i));
2580                         if (young)
2581                                 swp_entry = make_migration_entry_young(swp_entry);
2582                         if (dirty)
2583                                 swp_entry = make_migration_entry_dirty(swp_entry);
2584                         entry = swp_entry_to_pte(swp_entry);
2585                         if (soft_dirty)
2586                                 entry = pte_swp_mksoft_dirty(entry);
2587                         if (uffd_wp)
2588                                 entry = pte_swp_mkuffd_wp(entry);
2589                 } else {
2590                         entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));
2591                         if (write)
2592                                 entry = pte_mkwrite(entry, vma);
2593                         if (!young)
2594                                 entry = pte_mkold(entry);
2595                         /* NOTE: this may set soft-dirty too on some archs */
2596                         if (dirty)
2597                                 entry = pte_mkdirty(entry);
2598                         if (soft_dirty)
2599                                 entry = pte_mksoft_dirty(entry);
2600                         if (uffd_wp)
2601                                 entry = pte_mkuffd_wp(entry);
2602                 }
2603                 VM_BUG_ON(!pte_none(ptep_get(pte)));
2604                 set_pte_at(mm, addr, pte, entry);
2605                 pte++;
2606         }
2607         pte_unmap(pte - 1);
2608
2609         if (!pmd_migration)
2610                 folio_remove_rmap_pmd(folio, page, vma);
2611         if (freeze)
2612                 put_page(page);
2613
2614         smp_wmb(); /* make pte visible before pmd */
2615         pmd_populate(mm, pmd, pgtable);
2616 }
2617
2618 void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
2619                 unsigned long address, bool freeze, struct folio *folio)
2620 {
2621         spinlock_t *ptl;
2622         struct mmu_notifier_range range;
2623
2624         mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
2625                                 address & HPAGE_PMD_MASK,
2626                                 (address & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE);
2627         mmu_notifier_invalidate_range_start(&range);
2628         ptl = pmd_lock(vma->vm_mm, pmd);
2629
2630         /*
2631          * If caller asks to setup a migration entry, we need a folio to check
2632          * pmd against. Otherwise we can end up replacing wrong folio.
2633          */
2634         VM_BUG_ON(freeze && !folio);
2635         VM_WARN_ON_ONCE(folio && !folio_test_locked(folio));
2636
2637         if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd) ||
2638             is_pmd_migration_entry(*pmd)) {
2639                 /*
2640                  * It's safe to call pmd_page when folio is set because it's
2641                  * guaranteed that pmd is present.
2642                  */
2643                 if (folio && folio != page_folio(pmd_page(*pmd)))
2644                         goto out;
2645                 __split_huge_pmd_locked(vma, pmd, range.start, freeze);
2646         }
2647
2648 out:
2649         spin_unlock(ptl);
2650         mmu_notifier_invalidate_range_end(&range);
2651 }
2652
2653 void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
2654                 bool freeze, struct folio *folio)
2655 {
2656         pmd_t *pmd = mm_find_pmd(vma->vm_mm, address);
2657
2658         if (!pmd)
2659                 return;
2660
2661         __split_huge_pmd(vma, pmd, address, freeze, folio);
2662 }
2663
2664 static inline void split_huge_pmd_if_needed(struct vm_area_struct *vma, unsigned long address)
2665 {
2666         /*
2667          * If the new address isn't hpage aligned and it could previously
2668          * contain an hugepage: check if we need to split an huge pmd.
2669          */
2670         if (!IS_ALIGNED(address, HPAGE_PMD_SIZE) &&
2671             range_in_vma(vma, ALIGN_DOWN(address, HPAGE_PMD_SIZE),
2672                          ALIGN(address, HPAGE_PMD_SIZE)))
2673                 split_huge_pmd_address(vma, address, false, NULL);
2674 }
2675
2676 void vma_adjust_trans_huge(struct vm_area_struct *vma,
2677                              unsigned long start,
2678                              unsigned long end,
2679                              long adjust_next)
2680 {
2681         /* Check if we need to split start first. */
2682         split_huge_pmd_if_needed(vma, start);
2683
2684         /* Check if we need to split end next. */
2685         split_huge_pmd_if_needed(vma, end);
2686
2687         /*
2688          * If we're also updating the next vma vm_start,
2689          * check if we need to split it.
2690          */
2691         if (adjust_next > 0) {
2692                 struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end);
2693                 unsigned long nstart = next->vm_start;
2694                 nstart += adjust_next;
2695                 split_huge_pmd_if_needed(next, nstart);
2696         }
2697 }
2698
2699 static void unmap_folio(struct folio *folio)
2700 {
2701         enum ttu_flags ttu_flags = TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD |
2702                 TTU_SYNC | TTU_BATCH_FLUSH;
2703
2704         VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
2705
2706         /*
2707          * Anon pages need migration entries to preserve them, but file
2708          * pages can simply be left unmapped, then faulted back on demand.
2709          * If that is ever changed (perhaps for mlock), update remap_page().
2710          */
2711         if (folio_test_anon(folio))
2712                 try_to_migrate(folio, ttu_flags);
2713         else
2714                 try_to_unmap(folio, ttu_flags | TTU_IGNORE_MLOCK);
2715
2716         try_to_unmap_flush();
2717 }
2718
2719 static void remap_page(struct folio *folio, unsigned long nr)
2720 {
2721         int i = 0;
2722
2723         /* If unmap_folio() uses try_to_migrate() on file, remove this check */
2724         if (!folio_test_anon(folio))
2725                 return;
2726         for (;;) {
2727                 remove_migration_ptes(folio, folio, true);
2728                 i += folio_nr_pages(folio);
2729                 if (i >= nr)
2730                         break;
2731                 folio = folio_next(folio);
2732         }
2733 }
2734
2735 static void lru_add_page_tail(struct page *head, struct page *tail,
2736                 struct lruvec *lruvec, struct list_head *list)
2737 {
2738         VM_BUG_ON_PAGE(!PageHead(head), head);
2739         VM_BUG_ON_PAGE(PageCompound(tail), head);
2740         VM_BUG_ON_PAGE(PageLRU(tail), head);
2741         lockdep_assert_held(&lruvec->lru_lock);
2742
2743         if (list) {
2744                 /* page reclaim is reclaiming a huge page */
2745                 VM_WARN_ON(PageLRU(head));
2746                 get_page(tail);
2747                 list_add_tail(&tail->lru, list);
2748         } else {
2749                 /* head is still on lru (and we have it frozen) */
2750                 VM_WARN_ON(!PageLRU(head));
2751                 if (PageUnevictable(tail))
2752                         tail->mlock_count = 0;
2753                 else
2754                         list_add_tail(&tail->lru, &head->lru);
2755                 SetPageLRU(tail);
2756         }
2757 }
2758
2759 static void __split_huge_page_tail(struct folio *folio, int tail,
2760                 struct lruvec *lruvec, struct list_head *list)
2761 {
2762         struct page *head = &folio->page;
2763         struct page *page_tail = head + tail;
2764         /*
2765          * Careful: new_folio is not a "real" folio before we cleared PageTail.
2766          * Don't pass it around before clear_compound_head().
2767          */
2768         struct folio *new_folio = (struct folio *)page_tail;
2769
2770         VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
2771
2772         /*
2773          * Clone page flags before unfreezing refcount.
2774          *
2775          * After successful get_page_unless_zero() might follow flags change,
2776          * for example lock_page() which set PG_waiters.
2777          *
2778          * Note that for mapped sub-pages of an anonymous THP,
2779          * PG_anon_exclusive has been cleared in unmap_folio() and is stored in
2780          * the migration entry instead from where remap_page() will restore it.
2781          * We can still have PG_anon_exclusive set on effectively unmapped and
2782          * unreferenced sub-pages of an anonymous THP: we can simply drop
2783          * PG_anon_exclusive (-> PG_mappedtodisk) for these here.
2784          */
2785         page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
2786         page_tail->flags |= (head->flags &
2787                         ((1L << PG_referenced) |
2788                          (1L << PG_swapbacked) |
2789                          (1L << PG_swapcache) |
2790                          (1L << PG_mlocked) |
2791                          (1L << PG_uptodate) |
2792                          (1L << PG_active) |
2793                          (1L << PG_workingset) |
2794                          (1L << PG_locked) |
2795                          (1L << PG_unevictable) |
2796 #ifdef CONFIG_ARCH_USES_PG_ARCH_X
2797                          (1L << PG_arch_2) |
2798                          (1L << PG_arch_3) |
2799 #endif
2800                          (1L << PG_dirty) |
2801                          LRU_GEN_MASK | LRU_REFS_MASK));
2802
2803         /* ->mapping in first and second tail page is replaced by other uses */
2804         VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
2805                         page_tail);
2806         page_tail->mapping = head->mapping;
2807         page_tail->index = head->index + tail;
2808
2809         /*
2810          * page->private should not be set in tail pages. Fix up and warn once
2811          * if private is unexpectedly set.
2812          */
2813         if (unlikely(page_tail->private)) {
2814                 VM_WARN_ON_ONCE_PAGE(true, page_tail);
2815                 page_tail->private = 0;
2816         }
2817         if (folio_test_swapcache(folio))
2818                 new_folio->swap.val = folio->swap.val + tail;
2819
2820         /* Page flags must be visible before we make the page non-compound. */
2821         smp_wmb();
2822
2823         /*
2824          * Clear PageTail before unfreezing page refcount.
2825          *
2826          * After successful get_page_unless_zero() might follow put_page()
2827          * which needs correct compound_head().
2828          */
2829         clear_compound_head(page_tail);
2830
2831         /* Finally unfreeze refcount. Additional reference from page cache. */
2832         page_ref_unfreeze(page_tail, 1 + (!folio_test_anon(folio) ||
2833                                           folio_test_swapcache(folio)));
2834
2835         if (folio_test_young(folio))
2836                 folio_set_young(new_folio);
2837         if (folio_test_idle(folio))
2838                 folio_set_idle(new_folio);
2839
2840         folio_xchg_last_cpupid(new_folio, folio_last_cpupid(folio));
2841
2842         /*
2843          * always add to the tail because some iterators expect new
2844          * pages to show after the currently processed elements - e.g.
2845          * migrate_pages
2846          */
2847         lru_add_page_tail(head, page_tail, lruvec, list);
2848 }
2849
2850 static void __split_huge_page(struct page *page, struct list_head *list,
2851                 pgoff_t end)
2852 {
2853         struct folio *folio = page_folio(page);
2854         struct page *head = &folio->page;
2855         struct lruvec *lruvec;
2856         struct address_space *swap_cache = NULL;
2857         unsigned long offset = 0;
2858         unsigned int nr = thp_nr_pages(head);
2859         int i, nr_dropped = 0;
2860
2861         /* complete memcg works before add pages to LRU */
2862         split_page_memcg(head, nr);
2863
2864         if (folio_test_anon(folio) && folio_test_swapcache(folio)) {
2865                 offset = swp_offset(folio->swap);
2866                 swap_cache = swap_address_space(folio->swap);
2867                 xa_lock(&swap_cache->i_pages);
2868         }
2869
2870         /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
2871         lruvec = folio_lruvec_lock(folio);
2872
2873         ClearPageHasHWPoisoned(head);
2874
2875         for (i = nr - 1; i >= 1; i--) {
2876                 __split_huge_page_tail(folio, i, lruvec, list);
2877                 /* Some pages can be beyond EOF: drop them from page cache */
2878                 if (head[i].index >= end) {
2879                         struct folio *tail = page_folio(head + i);
2880
2881                         if (shmem_mapping(head->mapping))
2882                                 nr_dropped++;
2883                         else if (folio_test_clear_dirty(tail))
2884                                 folio_account_cleaned(tail,
2885                                         inode_to_wb(folio->mapping->host));
2886                         __filemap_remove_folio(tail, NULL);
2887                         folio_put(tail);
2888                 } else if (!PageAnon(page)) {
2889                         __xa_store(&head->mapping->i_pages, head[i].index,
2890                                         head + i, 0);
2891                 } else if (swap_cache) {
2892                         __xa_store(&swap_cache->i_pages, offset + i,
2893                                         head + i, 0);
2894                 }
2895         }
2896
2897         ClearPageCompound(head);
2898         unlock_page_lruvec(lruvec);
2899         /* Caller disabled irqs, so they are still disabled here */
2900
2901         split_page_owner(head, nr);
2902
2903         /* See comment in __split_huge_page_tail() */
2904         if (PageAnon(head)) {
2905                 /* Additional pin to swap cache */
2906                 if (PageSwapCache(head)) {
2907                         page_ref_add(head, 2);
2908                         xa_unlock(&swap_cache->i_pages);
2909                 } else {
2910                         page_ref_inc(head);
2911                 }
2912         } else {
2913                 /* Additional pin to page cache */
2914                 page_ref_add(head, 2);
2915                 xa_unlock(&head->mapping->i_pages);
2916         }
2917         local_irq_enable();
2918
2919         if (nr_dropped)
2920                 shmem_uncharge(head->mapping->host, nr_dropped);
2921         remap_page(folio, nr);
2922
2923         if (folio_test_swapcache(folio))
2924                 split_swap_cluster(folio->swap);
2925
2926         for (i = 0; i < nr; i++) {
2927                 struct page *subpage = head + i;
2928                 if (subpage == page)
2929                         continue;
2930                 unlock_page(subpage);
2931
2932                 /*
2933                  * Subpages may be freed if there wasn't any mapping
2934                  * like if add_to_swap() is running on a lru page that
2935                  * had its mapping zapped. And freeing these pages
2936                  * requires taking the lru_lock so we do the put_page
2937                  * of the tail pages after the split is complete.
2938                  */
2939                 free_page_and_swap_cache(subpage);
2940         }
2941 }
2942
2943 /* Racy check whether the huge page can be split */
2944 bool can_split_folio(struct folio *folio, int *pextra_pins)
2945 {
2946         int extra_pins;
2947
2948         /* Additional pins from page cache */
2949         if (folio_test_anon(folio))
2950                 extra_pins = folio_test_swapcache(folio) ?
2951                                 folio_nr_pages(folio) : 0;
2952         else
2953                 extra_pins = folio_nr_pages(folio);
2954         if (pextra_pins)
2955                 *pextra_pins = extra_pins;
2956         return folio_mapcount(folio) == folio_ref_count(folio) - extra_pins - 1;
2957 }
2958
2959 /*
2960  * This function splits huge page into normal pages. @page can point to any
2961  * subpage of huge page to split. Split doesn't change the position of @page.
2962  *
2963  * Only caller must hold pin on the @page, otherwise split fails with -EBUSY.
2964  * The huge page must be locked.
2965  *
2966  * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
2967  *
2968  * Both head page and tail pages will inherit mapping, flags, and so on from
2969  * the hugepage.
2970  *
2971  * GUP pin and PG_locked transferred to @page. Rest subpages can be freed if
2972  * they are not mapped.
2973  *
2974  * Returns 0 if the hugepage is split successfully.
2975  * Returns -EBUSY if the page is pinned or if anon_vma disappeared from under
2976  * us.
2977  */
2978 int split_huge_page_to_list(struct page *page, struct list_head *list)
2979 {
2980         struct folio *folio = page_folio(page);
2981         struct deferred_split *ds_queue = get_deferred_split_queue(folio);
2982         XA_STATE(xas, &folio->mapping->i_pages, folio->index);
2983         struct anon_vma *anon_vma = NULL;
2984         struct address_space *mapping = NULL;
2985         int extra_pins, ret;
2986         pgoff_t end;
2987         bool is_hzp;
2988
2989         VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
2990         VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
2991
2992         is_hzp = is_huge_zero_page(&folio->page);
2993         if (is_hzp) {
2994                 pr_warn_ratelimited("Called split_huge_page for huge zero page\n");
2995                 return -EBUSY;
2996         }
2997
2998         if (folio_test_writeback(folio))
2999                 return -EBUSY;
3000
3001         if (folio_test_anon(folio)) {
3002                 /*
3003                  * The caller does not necessarily hold an mmap_lock that would
3004                  * prevent the anon_vma disappearing so we first we take a
3005                  * reference to it and then lock the anon_vma for write. This
3006                  * is similar to folio_lock_anon_vma_read except the write lock
3007                  * is taken to serialise against parallel split or collapse
3008                  * operations.
3009                  */
3010                 anon_vma = folio_get_anon_vma(folio);
3011                 if (!anon_vma) {
3012                         ret = -EBUSY;
3013                         goto out;
3014                 }
3015                 end = -1;
3016                 mapping = NULL;
3017                 anon_vma_lock_write(anon_vma);
3018         } else {
3019                 gfp_t gfp;
3020
3021                 mapping = folio->mapping;
3022
3023                 /* Truncated ? */
3024                 if (!mapping) {
3025                         ret = -EBUSY;
3026                         goto out;
3027                 }
3028
3029                 gfp = current_gfp_context(mapping_gfp_mask(mapping) &
3030                                                         GFP_RECLAIM_MASK);
3031
3032                 if (!filemap_release_folio(folio, gfp)) {
3033                         ret = -EBUSY;
3034                         goto out;
3035                 }
3036
3037                 xas_split_alloc(&xas, folio, folio_order(folio), gfp);
3038                 if (xas_error(&xas)) {
3039                         ret = xas_error(&xas);
3040                         goto out;
3041                 }
3042
3043                 anon_vma = NULL;
3044                 i_mmap_lock_read(mapping);
3045
3046                 /*
3047                  *__split_huge_page() may need to trim off pages beyond EOF:
3048                  * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
3049                  * which cannot be nested inside the page tree lock. So note
3050                  * end now: i_size itself may be changed at any moment, but
3051                  * folio lock is good enough to serialize the trimming.
3052                  */
3053                 end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
3054                 if (shmem_mapping(mapping))
3055                         end = shmem_fallocend(mapping->host, end);
3056         }
3057
3058         /*
3059          * Racy check if we can split the page, before unmap_folio() will
3060          * split PMDs
3061          */
3062         if (!can_split_folio(folio, &extra_pins)) {
3063                 ret = -EAGAIN;
3064                 goto out_unlock;
3065         }
3066
3067         unmap_folio(folio);
3068
3069         /* block interrupt reentry in xa_lock and spinlock */
3070         local_irq_disable();
3071         if (mapping) {
3072                 /*
3073                  * Check if the folio is present in page cache.
3074                  * We assume all tail are present too, if folio is there.
3075                  */
3076                 xas_lock(&xas);
3077                 xas_reset(&xas);
3078                 if (xas_load(&xas) != folio)
3079                         goto fail;
3080         }
3081
3082         /* Prevent deferred_split_scan() touching ->_refcount */
3083         spin_lock(&ds_queue->split_queue_lock);
3084         if (folio_ref_freeze(folio, 1 + extra_pins)) {
3085                 if (!list_empty(&folio->_deferred_list)) {
3086                         ds_queue->split_queue_len--;
3087                         list_del(&folio->_deferred_list);
3088                 }
3089                 spin_unlock(&ds_queue->split_queue_lock);
3090                 if (mapping) {
3091                         int nr = folio_nr_pages(folio);
3092
3093                         xas_split(&xas, folio, folio_order(folio));
3094                         if (folio_test_pmd_mappable(folio)) {
3095                                 if (folio_test_swapbacked(folio)) {
3096                                         __lruvec_stat_mod_folio(folio,
3097                                                         NR_SHMEM_THPS, -nr);
3098                                 } else {
3099                                         __lruvec_stat_mod_folio(folio,
3100                                                         NR_FILE_THPS, -nr);
3101                                         filemap_nr_thps_dec(mapping);
3102                                 }
3103                         }
3104                 }
3105
3106                 __split_huge_page(page, list, end);
3107                 ret = 0;
3108         } else {
3109                 spin_unlock(&ds_queue->split_queue_lock);
3110 fail:
3111                 if (mapping)
3112                         xas_unlock(&xas);
3113                 local_irq_enable();
3114                 remap_page(folio, folio_nr_pages(folio));
3115                 ret = -EAGAIN;
3116         }
3117
3118 out_unlock:
3119         if (anon_vma) {
3120                 anon_vma_unlock_write(anon_vma);
3121                 put_anon_vma(anon_vma);
3122         }
3123         if (mapping)
3124                 i_mmap_unlock_read(mapping);
3125 out:
3126         xas_destroy(&xas);
3127         count_vm_event(!ret ? THP_SPLIT_PAGE : THP_SPLIT_PAGE_FAILED);
3128         return ret;
3129 }
3130
3131 void folio_undo_large_rmappable(struct folio *folio)
3132 {
3133         struct deferred_split *ds_queue;
3134         unsigned long flags;
3135
3136         /*
3137          * At this point, there is no one trying to add the folio to
3138          * deferred_list. If folio is not in deferred_list, it's safe
3139          * to check without acquiring the split_queue_lock.
3140          */
3141         if (data_race(list_empty(&folio->_deferred_list)))
3142                 return;
3143
3144         ds_queue = get_deferred_split_queue(folio);
3145         spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
3146         if (!list_empty(&folio->_deferred_list)) {
3147                 ds_queue->split_queue_len--;
3148                 list_del_init(&folio->_deferred_list);
3149         }
3150         spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
3151 }
3152
3153 void deferred_split_folio(struct folio *folio)
3154 {
3155         struct deferred_split *ds_queue = get_deferred_split_queue(folio);
3156 #ifdef CONFIG_MEMCG
3157         struct mem_cgroup *memcg = folio_memcg(folio);
3158 #endif
3159         unsigned long flags;
3160
3161         VM_BUG_ON_FOLIO(folio_order(folio) < 2, folio);
3162
3163         /*
3164          * The try_to_unmap() in page reclaim path might reach here too,
3165          * this may cause a race condition to corrupt deferred split queue.
3166          * And, if page reclaim is already handling the same folio, it is
3167          * unnecessary to handle it again in shrinker.
3168          *
3169          * Check the swapcache flag to determine if the folio is being
3170          * handled by page reclaim since THP swap would add the folio into
3171          * swap cache before calling try_to_unmap().
3172          */
3173         if (folio_test_swapcache(folio))
3174                 return;
3175
3176         if (!list_empty(&folio->_deferred_list))
3177                 return;
3178
3179         spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
3180         if (list_empty(&folio->_deferred_list)) {
3181                 count_vm_event(THP_DEFERRED_SPLIT_PAGE);
3182                 list_add_tail(&folio->_deferred_list, &ds_queue->split_queue);
3183                 ds_queue->split_queue_len++;
3184 #ifdef CONFIG_MEMCG
3185                 if (memcg)
3186                         set_shrinker_bit(memcg, folio_nid(folio),
3187                                          deferred_split_shrinker->id);
3188 #endif
3189         }
3190         spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
3191 }
3192
3193 static unsigned long deferred_split_count(struct shrinker *shrink,
3194                 struct shrink_control *sc)
3195 {
3196         struct pglist_data *pgdata = NODE_DATA(sc->nid);
3197         struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
3198
3199 #ifdef CONFIG_MEMCG
3200         if (sc->memcg)
3201                 ds_queue = &sc->memcg->deferred_split_queue;
3202 #endif
3203         return READ_ONCE(ds_queue->split_queue_len);
3204 }
3205
3206 static unsigned long deferred_split_scan(struct shrinker *shrink,
3207                 struct shrink_control *sc)
3208 {
3209         struct pglist_data *pgdata = NODE_DATA(sc->nid);
3210         struct deferred_split *ds_queue = &pgdata->deferred_split_queue;
3211         unsigned long flags;
3212         LIST_HEAD(list);
3213         struct folio *folio, *next;
3214         int split = 0;
3215
3216 #ifdef CONFIG_MEMCG
3217         if (sc->memcg)
3218                 ds_queue = &sc->memcg->deferred_split_queue;
3219 #endif
3220
3221         spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
3222         /* Take pin on all head pages to avoid freeing them under us */
3223         list_for_each_entry_safe(folio, next, &ds_queue->split_queue,
3224                                                         _deferred_list) {
3225                 if (folio_try_get(folio)) {
3226                         list_move(&folio->_deferred_list, &list);
3227                 } else {
3228                         /* We lost race with folio_put() */
3229                         list_del_init(&folio->_deferred_list);
3230                         ds_queue->split_queue_len--;
3231                 }
3232                 if (!--sc->nr_to_scan)
3233                         break;
3234         }
3235         spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
3236
3237         list_for_each_entry_safe(folio, next, &list, _deferred_list) {
3238                 if (!folio_trylock(folio))
3239                         goto next;
3240                 /* split_huge_page() removes page from list on success */
3241                 if (!split_folio(folio))
3242                         split++;
3243                 folio_unlock(folio);
3244 next:
3245                 folio_put(folio);
3246         }
3247
3248         spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
3249         list_splice_tail(&list, &ds_queue->split_queue);
3250         spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
3251
3252         /*
3253          * Stop shrinker if we didn't split any page, but the queue is empty.
3254          * This can happen if pages were freed under us.
3255          */
3256         if (!split && list_empty(&ds_queue->split_queue))
3257                 return SHRINK_STOP;
3258         return split;
3259 }
3260
3261 #ifdef CONFIG_DEBUG_FS
3262 static void split_huge_pages_all(void)
3263 {
3264         struct zone *zone;
3265         struct page *page;
3266         struct folio *folio;
3267         unsigned long pfn, max_zone_pfn;
3268         unsigned long total = 0, split = 0;
3269
3270         pr_debug("Split all THPs\n");
3271         for_each_zone(zone) {
3272                 if (!managed_zone(zone))
3273                         continue;
3274                 max_zone_pfn = zone_end_pfn(zone);
3275                 for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
3276                         int nr_pages;
3277
3278                         page = pfn_to_online_page(pfn);
3279                         if (!page || PageTail(page))
3280                                 continue;
3281                         folio = page_folio(page);
3282                         if (!folio_try_get(folio))
3283                                 continue;
3284
3285                         if (unlikely(page_folio(page) != folio))
3286                                 goto next;
3287
3288                         if (zone != folio_zone(folio))
3289                                 goto next;
3290
3291                         if (!folio_test_large(folio)
3292                                 || folio_test_hugetlb(folio)
3293                                 || !folio_test_lru(folio))
3294                                 goto next;
3295
3296                         total++;
3297                         folio_lock(folio);
3298                         nr_pages = folio_nr_pages(folio);
3299                         if (!split_folio(folio))
3300                                 split++;
3301                         pfn += nr_pages - 1;
3302                         folio_unlock(folio);
3303 next:
3304                         folio_put(folio);
3305                         cond_resched();
3306                 }
3307         }
3308
3309         pr_debug("%lu of %lu THP split\n", split, total);
3310 }
3311
3312 static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma)
3313 {
3314         return vma_is_special_huge(vma) || (vma->vm_flags & VM_IO) ||
3315                     is_vm_hugetlb_page(vma);
3316 }
3317
3318 static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
3319                                 unsigned long vaddr_end)
3320 {
3321         int ret = 0;
3322         struct task_struct *task;
3323         struct mm_struct *mm;
3324         unsigned long total = 0, split = 0;
3325         unsigned long addr;
3326
3327         vaddr_start &= PAGE_MASK;
3328         vaddr_end &= PAGE_MASK;
3329
3330         /* Find the task_struct from pid */
3331         rcu_read_lock();
3332         task = find_task_by_vpid(pid);
3333         if (!task) {
3334                 rcu_read_unlock();
3335                 ret = -ESRCH;
3336                 goto out;
3337         }
3338         get_task_struct(task);
3339         rcu_read_unlock();
3340
3341         /* Find the mm_struct */
3342         mm = get_task_mm(task);
3343         put_task_struct(task);
3344
3345         if (!mm) {
3346                 ret = -EINVAL;
3347                 goto out;
3348         }
3349
3350         pr_debug("Split huge pages in pid: %d, vaddr: [0x%lx - 0x%lx]\n",
3351                  pid, vaddr_start, vaddr_end);
3352
3353         mmap_read_lock(mm);
3354         /*
3355          * always increase addr by PAGE_SIZE, since we could have a PTE page
3356          * table filled with PTE-mapped THPs, each of which is distinct.
3357          */
3358         for (addr = vaddr_start; addr < vaddr_end; addr += PAGE_SIZE) {
3359                 struct vm_area_struct *vma = vma_lookup(mm, addr);
3360                 struct page *page;
3361                 struct folio *folio;
3362
3363                 if (!vma)
3364                         break;
3365
3366                 /* skip special VMA and hugetlb VMA */
3367                 if (vma_not_suitable_for_thp_split(vma)) {
3368                         addr = vma->vm_end;
3369                         continue;
3370                 }
3371
3372                 /* FOLL_DUMP to ignore special (like zero) pages */
3373                 page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
3374
3375                 if (IS_ERR_OR_NULL(page))
3376                         continue;
3377
3378                 folio = page_folio(page);
3379                 if (!is_transparent_hugepage(folio))
3380                         goto next;
3381
3382                 total++;
3383                 if (!can_split_folio(folio, NULL))
3384                         goto next;
3385
3386                 if (!folio_trylock(folio))
3387                         goto next;
3388
3389                 if (!split_folio(folio))
3390                         split++;
3391
3392                 folio_unlock(folio);
3393 next:
3394                 folio_put(folio);
3395                 cond_resched();
3396         }
3397         mmap_read_unlock(mm);
3398         mmput(mm);
3399
3400         pr_debug("%lu of %lu THP split\n", split, total);
3401
3402 out:
3403         return ret;
3404 }
3405
3406 static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
3407                                 pgoff_t off_end)
3408 {
3409         struct filename *file;
3410         struct file *candidate;
3411         struct address_space *mapping;
3412         int ret = -EINVAL;
3413         pgoff_t index;
3414         int nr_pages = 1;
3415         unsigned long total = 0, split = 0;
3416
3417         file = getname_kernel(file_path);
3418         if (IS_ERR(file))
3419                 return ret;
3420
3421         candidate = file_open_name(file, O_RDONLY, 0);
3422         if (IS_ERR(candidate))
3423                 goto out;
3424
3425         pr_debug("split file-backed THPs in file: %s, page offset: [0x%lx - 0x%lx]\n",
3426                  file_path, off_start, off_end);
3427
3428         mapping = candidate->f_mapping;
3429
3430         for (index = off_start; index < off_end; index += nr_pages) {
3431                 struct folio *folio = filemap_get_folio(mapping, index);
3432
3433                 nr_pages = 1;
3434                 if (IS_ERR(folio))
3435                         continue;
3436
3437                 if (!folio_test_large(folio))
3438                         goto next;
3439
3440                 total++;
3441                 nr_pages = folio_nr_pages(folio);
3442
3443                 if (!folio_trylock(folio))
3444                         goto next;
3445
3446                 if (!split_folio(folio))
3447                         split++;
3448
3449                 folio_unlock(folio);
3450 next:
3451                 folio_put(folio);
3452                 cond_resched();
3453         }
3454
3455         filp_close(candidate, NULL);
3456         ret = 0;
3457
3458         pr_debug("%lu of %lu file-backed THP split\n", split, total);
3459 out:
3460         putname(file);
3461         return ret;
3462 }
3463
3464 #define MAX_INPUT_BUF_SZ 255
3465
3466 static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
3467                                 size_t count, loff_t *ppops)
3468 {
3469         static DEFINE_MUTEX(split_debug_mutex);
3470         ssize_t ret;
3471         /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */
3472         char input_buf[MAX_INPUT_BUF_SZ];
3473         int pid;
3474         unsigned long vaddr_start, vaddr_end;
3475
3476         ret = mutex_lock_interruptible(&split_debug_mutex);
3477         if (ret)
3478                 return ret;
3479
3480         ret = -EFAULT;
3481
3482         memset(input_buf, 0, MAX_INPUT_BUF_SZ);
3483         if (copy_from_user(input_buf, buf, min_t(size_t, count, MAX_INPUT_BUF_SZ)))
3484                 goto out;
3485
3486         input_buf[MAX_INPUT_BUF_SZ - 1] = '\0';
3487
3488         if (input_buf[0] == '/') {
3489                 char *tok;
3490                 char *buf = input_buf;
3491                 char file_path[MAX_INPUT_BUF_SZ];
3492                 pgoff_t off_start = 0, off_end = 0;
3493                 size_t input_len = strlen(input_buf);
3494
3495                 tok = strsep(&buf, ",");
3496                 if (tok) {
3497                         strcpy(file_path, tok);
3498                 } else {
3499                         ret = -EINVAL;
3500                         goto out;
3501                 }
3502
3503                 ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end);
3504                 if (ret != 2) {
3505                         ret = -EINVAL;
3506                         goto out;
3507                 }
3508                 ret = split_huge_pages_in_file(file_path, off_start, off_end);
3509                 if (!ret)
3510                         ret = input_len;
3511
3512                 goto out;
3513         }
3514
3515         ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end);
3516         if (ret == 1 && pid == 1) {
3517                 split_huge_pages_all();
3518                 ret = strlen(input_buf);
3519                 goto out;
3520         } else if (ret != 3) {
3521                 ret = -EINVAL;
3522                 goto out;
3523         }
3524
3525         ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end);
3526         if (!ret)
3527                 ret = strlen(input_buf);
3528 out:
3529         mutex_unlock(&split_debug_mutex);
3530         return ret;
3531
3532 }
3533
3534 static const struct file_operations split_huge_pages_fops = {
3535         .owner   = THIS_MODULE,
3536         .write   = split_huge_pages_write,
3537         .llseek  = no_llseek,
3538 };
3539
3540 static int __init split_huge_pages_debugfs(void)
3541 {
3542         debugfs_create_file("split_huge_pages", 0200, NULL, NULL,
3543                             &split_huge_pages_fops);
3544         return 0;
3545 }
3546 late_initcall(split_huge_pages_debugfs);
3547 #endif
3548
3549 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
3550 int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
3551                 struct page *page)
3552 {
3553         struct folio *folio = page_folio(page);
3554         struct vm_area_struct *vma = pvmw->vma;
3555         struct mm_struct *mm = vma->vm_mm;
3556         unsigned long address = pvmw->address;
3557         bool anon_exclusive;
3558         pmd_t pmdval;
3559         swp_entry_t entry;
3560         pmd_t pmdswp;
3561
3562         if (!(pvmw->pmd && !pvmw->pte))
3563                 return 0;
3564
3565         flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
3566         pmdval = pmdp_invalidate(vma, address, pvmw->pmd);
3567
3568         /* See folio_try_share_anon_rmap_pmd(): invalidate PMD first. */
3569         anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(page);
3570         if (anon_exclusive && folio_try_share_anon_rmap_pmd(folio, page)) {
3571                 set_pmd_at(mm, address, pvmw->pmd, pmdval);
3572                 return -EBUSY;
3573         }
3574
3575         if (pmd_dirty(pmdval))
3576                 folio_mark_dirty(folio);
3577         if (pmd_write(pmdval))
3578                 entry = make_writable_migration_entry(page_to_pfn(page));
3579         else if (anon_exclusive)
3580                 entry = make_readable_exclusive_migration_entry(page_to_pfn(page));
3581         else
3582                 entry = make_readable_migration_entry(page_to_pfn(page));
3583         if (pmd_young(pmdval))
3584                 entry = make_migration_entry_young(entry);
3585         if (pmd_dirty(pmdval))
3586                 entry = make_migration_entry_dirty(entry);
3587         pmdswp = swp_entry_to_pmd(entry);
3588         if (pmd_soft_dirty(pmdval))
3589                 pmdswp = pmd_swp_mksoft_dirty(pmdswp);
3590         if (pmd_uffd_wp(pmdval))
3591                 pmdswp = pmd_swp_mkuffd_wp(pmdswp);
3592         set_pmd_at(mm, address, pvmw->pmd, pmdswp);
3593         folio_remove_rmap_pmd(folio, page, vma);
3594         folio_put(folio);
3595         trace_set_migration_pmd(address, pmd_val(pmdswp));
3596
3597         return 0;
3598 }
3599
3600 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
3601 {
3602         struct folio *folio = page_folio(new);
3603         struct vm_area_struct *vma = pvmw->vma;
3604         struct mm_struct *mm = vma->vm_mm;
3605         unsigned long address = pvmw->address;
3606         unsigned long haddr = address & HPAGE_PMD_MASK;
3607         pmd_t pmde;
3608         swp_entry_t entry;
3609
3610         if (!(pvmw->pmd && !pvmw->pte))
3611                 return;
3612
3613         entry = pmd_to_swp_entry(*pvmw->pmd);
3614         folio_get(folio);
3615         pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot));
3616         if (pmd_swp_soft_dirty(*pvmw->pmd))
3617                 pmde = pmd_mksoft_dirty(pmde);
3618         if (is_writable_migration_entry(entry))
3619                 pmde = pmd_mkwrite(pmde, vma);
3620         if (pmd_swp_uffd_wp(*pvmw->pmd))
3621                 pmde = pmd_mkuffd_wp(pmde);
3622         if (!is_migration_entry_young(entry))
3623                 pmde = pmd_mkold(pmde);
3624         /* NOTE: this may contain setting soft-dirty on some archs */
3625         if (folio_test_dirty(folio) && is_migration_entry_dirty(entry))
3626                 pmde = pmd_mkdirty(pmde);
3627
3628         if (folio_test_anon(folio)) {
3629                 rmap_t rmap_flags = RMAP_NONE;
3630
3631                 if (!is_readable_migration_entry(entry))
3632                         rmap_flags |= RMAP_EXCLUSIVE;
3633
3634                 folio_add_anon_rmap_pmd(folio, new, vma, haddr, rmap_flags);
3635         } else {
3636                 folio_add_file_rmap_pmd(folio, new, vma);
3637         }
3638         VM_BUG_ON(pmd_write(pmde) && folio_test_anon(folio) && !PageAnonExclusive(new));
3639         set_pmd_at(mm, haddr, pvmw->pmd, pmde);
3640
3641         /* No need to invalidate - it was non-present before */
3642         update_mmu_cache_pmd(vma, address, pvmw->pmd);
3643         trace_remove_migration_pmd(address, pmd_val(pmde));
3644 }
3645 #endif