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