| 1 | /* |
| 2 | * Generic hugetlb support. |
| 3 | * (C) William Irwin, April 2004 |
| 4 | */ |
| 5 | #include <linux/gfp.h> |
| 6 | #include <linux/list.h> |
| 7 | #include <linux/init.h> |
| 8 | #include <linux/module.h> |
| 9 | #include <linux/mm.h> |
| 10 | #include <linux/sysctl.h> |
| 11 | #include <linux/highmem.h> |
| 12 | #include <linux/nodemask.h> |
| 13 | #include <linux/pagemap.h> |
| 14 | #include <linux/mempolicy.h> |
| 15 | #include <linux/cpuset.h> |
| 16 | #include <linux/mutex.h> |
| 17 | |
| 18 | #include <asm/page.h> |
| 19 | #include <asm/pgtable.h> |
| 20 | |
| 21 | #include <linux/hugetlb.h> |
| 22 | #include "internal.h" |
| 23 | |
| 24 | const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL; |
| 25 | static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages; |
| 26 | static unsigned long surplus_huge_pages; |
| 27 | unsigned long max_huge_pages; |
| 28 | static struct list_head hugepage_freelists[MAX_NUMNODES]; |
| 29 | static unsigned int nr_huge_pages_node[MAX_NUMNODES]; |
| 30 | static unsigned int free_huge_pages_node[MAX_NUMNODES]; |
| 31 | static unsigned int surplus_huge_pages_node[MAX_NUMNODES]; |
| 32 | static gfp_t htlb_alloc_mask = GFP_HIGHUSER; |
| 33 | unsigned long hugepages_treat_as_movable; |
| 34 | int hugetlb_dynamic_pool; |
| 35 | |
| 36 | /* |
| 37 | * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages |
| 38 | */ |
| 39 | static DEFINE_SPINLOCK(hugetlb_lock); |
| 40 | |
| 41 | static void clear_huge_page(struct page *page, unsigned long addr) |
| 42 | { |
| 43 | int i; |
| 44 | |
| 45 | might_sleep(); |
| 46 | for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) { |
| 47 | cond_resched(); |
| 48 | clear_user_highpage(page + i, addr + i * PAGE_SIZE); |
| 49 | } |
| 50 | } |
| 51 | |
| 52 | static void copy_huge_page(struct page *dst, struct page *src, |
| 53 | unsigned long addr, struct vm_area_struct *vma) |
| 54 | { |
| 55 | int i; |
| 56 | |
| 57 | might_sleep(); |
| 58 | for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) { |
| 59 | cond_resched(); |
| 60 | copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | static void enqueue_huge_page(struct page *page) |
| 65 | { |
| 66 | int nid = page_to_nid(page); |
| 67 | list_add(&page->lru, &hugepage_freelists[nid]); |
| 68 | free_huge_pages++; |
| 69 | free_huge_pages_node[nid]++; |
| 70 | } |
| 71 | |
| 72 | static struct page *dequeue_huge_page(struct vm_area_struct *vma, |
| 73 | unsigned long address) |
| 74 | { |
| 75 | int nid; |
| 76 | struct page *page = NULL; |
| 77 | struct mempolicy *mpol; |
| 78 | struct zonelist *zonelist = huge_zonelist(vma, address, |
| 79 | htlb_alloc_mask, &mpol); |
| 80 | struct zone **z; |
| 81 | |
| 82 | for (z = zonelist->zones; *z; z++) { |
| 83 | nid = zone_to_nid(*z); |
| 84 | if (cpuset_zone_allowed_softwall(*z, htlb_alloc_mask) && |
| 85 | !list_empty(&hugepage_freelists[nid])) { |
| 86 | page = list_entry(hugepage_freelists[nid].next, |
| 87 | struct page, lru); |
| 88 | list_del(&page->lru); |
| 89 | free_huge_pages--; |
| 90 | free_huge_pages_node[nid]--; |
| 91 | if (vma && vma->vm_flags & VM_MAYSHARE) |
| 92 | resv_huge_pages--; |
| 93 | break; |
| 94 | } |
| 95 | } |
| 96 | mpol_free(mpol); /* unref if mpol !NULL */ |
| 97 | return page; |
| 98 | } |
| 99 | |
| 100 | static void update_and_free_page(struct page *page) |
| 101 | { |
| 102 | int i; |
| 103 | nr_huge_pages--; |
| 104 | nr_huge_pages_node[page_to_nid(page)]--; |
| 105 | for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) { |
| 106 | page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced | |
| 107 | 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved | |
| 108 | 1 << PG_private | 1<< PG_writeback); |
| 109 | } |
| 110 | set_compound_page_dtor(page, NULL); |
| 111 | set_page_refcounted(page); |
| 112 | __free_pages(page, HUGETLB_PAGE_ORDER); |
| 113 | } |
| 114 | |
| 115 | static void free_huge_page(struct page *page) |
| 116 | { |
| 117 | int nid = page_to_nid(page); |
| 118 | |
| 119 | BUG_ON(page_count(page)); |
| 120 | INIT_LIST_HEAD(&page->lru); |
| 121 | |
| 122 | spin_lock(&hugetlb_lock); |
| 123 | if (surplus_huge_pages_node[nid]) { |
| 124 | update_and_free_page(page); |
| 125 | surplus_huge_pages--; |
| 126 | surplus_huge_pages_node[nid]--; |
| 127 | } else { |
| 128 | enqueue_huge_page(page); |
| 129 | } |
| 130 | spin_unlock(&hugetlb_lock); |
| 131 | } |
| 132 | |
| 133 | /* |
| 134 | * Increment or decrement surplus_huge_pages. Keep node-specific counters |
| 135 | * balanced by operating on them in a round-robin fashion. |
| 136 | * Returns 1 if an adjustment was made. |
| 137 | */ |
| 138 | static int adjust_pool_surplus(int delta) |
| 139 | { |
| 140 | static int prev_nid; |
| 141 | int nid = prev_nid; |
| 142 | int ret = 0; |
| 143 | |
| 144 | VM_BUG_ON(delta != -1 && delta != 1); |
| 145 | do { |
| 146 | nid = next_node(nid, node_online_map); |
| 147 | if (nid == MAX_NUMNODES) |
| 148 | nid = first_node(node_online_map); |
| 149 | |
| 150 | /* To shrink on this node, there must be a surplus page */ |
| 151 | if (delta < 0 && !surplus_huge_pages_node[nid]) |
| 152 | continue; |
| 153 | /* Surplus cannot exceed the total number of pages */ |
| 154 | if (delta > 0 && surplus_huge_pages_node[nid] >= |
| 155 | nr_huge_pages_node[nid]) |
| 156 | continue; |
| 157 | |
| 158 | surplus_huge_pages += delta; |
| 159 | surplus_huge_pages_node[nid] += delta; |
| 160 | ret = 1; |
| 161 | break; |
| 162 | } while (nid != prev_nid); |
| 163 | |
| 164 | prev_nid = nid; |
| 165 | return ret; |
| 166 | } |
| 167 | |
| 168 | static int alloc_fresh_huge_page(void) |
| 169 | { |
| 170 | static int prev_nid; |
| 171 | struct page *page; |
| 172 | int nid; |
| 173 | |
| 174 | /* |
| 175 | * Copy static prev_nid to local nid, work on that, then copy it |
| 176 | * back to prev_nid afterwards: otherwise there's a window in which |
| 177 | * a racer might pass invalid nid MAX_NUMNODES to alloc_pages_node. |
| 178 | * But we don't need to use a spin_lock here: it really doesn't |
| 179 | * matter if occasionally a racer chooses the same nid as we do. |
| 180 | */ |
| 181 | nid = next_node(prev_nid, node_online_map); |
| 182 | if (nid == MAX_NUMNODES) |
| 183 | nid = first_node(node_online_map); |
| 184 | prev_nid = nid; |
| 185 | |
| 186 | page = alloc_pages_node(nid, htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN, |
| 187 | HUGETLB_PAGE_ORDER); |
| 188 | if (page) { |
| 189 | set_compound_page_dtor(page, free_huge_page); |
| 190 | spin_lock(&hugetlb_lock); |
| 191 | nr_huge_pages++; |
| 192 | nr_huge_pages_node[page_to_nid(page)]++; |
| 193 | spin_unlock(&hugetlb_lock); |
| 194 | put_page(page); /* free it into the hugepage allocator */ |
| 195 | return 1; |
| 196 | } |
| 197 | return 0; |
| 198 | } |
| 199 | |
| 200 | static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma, |
| 201 | unsigned long address) |
| 202 | { |
| 203 | struct page *page; |
| 204 | |
| 205 | /* Check if the dynamic pool is enabled */ |
| 206 | if (!hugetlb_dynamic_pool) |
| 207 | return NULL; |
| 208 | |
| 209 | page = alloc_pages(htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN, |
| 210 | HUGETLB_PAGE_ORDER); |
| 211 | if (page) { |
| 212 | set_compound_page_dtor(page, free_huge_page); |
| 213 | spin_lock(&hugetlb_lock); |
| 214 | nr_huge_pages++; |
| 215 | nr_huge_pages_node[page_to_nid(page)]++; |
| 216 | surplus_huge_pages++; |
| 217 | surplus_huge_pages_node[page_to_nid(page)]++; |
| 218 | spin_unlock(&hugetlb_lock); |
| 219 | } |
| 220 | |
| 221 | return page; |
| 222 | } |
| 223 | |
| 224 | /* |
| 225 | * Increase the hugetlb pool such that it can accomodate a reservation |
| 226 | * of size 'delta'. |
| 227 | */ |
| 228 | static int gather_surplus_pages(int delta) |
| 229 | { |
| 230 | struct list_head surplus_list; |
| 231 | struct page *page, *tmp; |
| 232 | int ret, i; |
| 233 | int needed, allocated; |
| 234 | |
| 235 | needed = (resv_huge_pages + delta) - free_huge_pages; |
| 236 | if (needed <= 0) |
| 237 | return 0; |
| 238 | |
| 239 | allocated = 0; |
| 240 | INIT_LIST_HEAD(&surplus_list); |
| 241 | |
| 242 | ret = -ENOMEM; |
| 243 | retry: |
| 244 | spin_unlock(&hugetlb_lock); |
| 245 | for (i = 0; i < needed; i++) { |
| 246 | page = alloc_buddy_huge_page(NULL, 0); |
| 247 | if (!page) { |
| 248 | /* |
| 249 | * We were not able to allocate enough pages to |
| 250 | * satisfy the entire reservation so we free what |
| 251 | * we've allocated so far. |
| 252 | */ |
| 253 | spin_lock(&hugetlb_lock); |
| 254 | needed = 0; |
| 255 | goto free; |
| 256 | } |
| 257 | |
| 258 | list_add(&page->lru, &surplus_list); |
| 259 | } |
| 260 | allocated += needed; |
| 261 | |
| 262 | /* |
| 263 | * After retaking hugetlb_lock, we need to recalculate 'needed' |
| 264 | * because either resv_huge_pages or free_huge_pages may have changed. |
| 265 | */ |
| 266 | spin_lock(&hugetlb_lock); |
| 267 | needed = (resv_huge_pages + delta) - (free_huge_pages + allocated); |
| 268 | if (needed > 0) |
| 269 | goto retry; |
| 270 | |
| 271 | /* |
| 272 | * The surplus_list now contains _at_least_ the number of extra pages |
| 273 | * needed to accomodate the reservation. Add the appropriate number |
| 274 | * of pages to the hugetlb pool and free the extras back to the buddy |
| 275 | * allocator. |
| 276 | */ |
| 277 | needed += allocated; |
| 278 | ret = 0; |
| 279 | free: |
| 280 | list_for_each_entry_safe(page, tmp, &surplus_list, lru) { |
| 281 | list_del(&page->lru); |
| 282 | if ((--needed) >= 0) |
| 283 | enqueue_huge_page(page); |
| 284 | else |
| 285 | update_and_free_page(page); |
| 286 | } |
| 287 | |
| 288 | return ret; |
| 289 | } |
| 290 | |
| 291 | /* |
| 292 | * When releasing a hugetlb pool reservation, any surplus pages that were |
| 293 | * allocated to satisfy the reservation must be explicitly freed if they were |
| 294 | * never used. |
| 295 | */ |
| 296 | void return_unused_surplus_pages(unsigned long unused_resv_pages) |
| 297 | { |
| 298 | static int nid = -1; |
| 299 | struct page *page; |
| 300 | unsigned long nr_pages; |
| 301 | |
| 302 | nr_pages = min(unused_resv_pages, surplus_huge_pages); |
| 303 | |
| 304 | while (nr_pages) { |
| 305 | nid = next_node(nid, node_online_map); |
| 306 | if (nid == MAX_NUMNODES) |
| 307 | nid = first_node(node_online_map); |
| 308 | |
| 309 | if (!surplus_huge_pages_node[nid]) |
| 310 | continue; |
| 311 | |
| 312 | if (!list_empty(&hugepage_freelists[nid])) { |
| 313 | page = list_entry(hugepage_freelists[nid].next, |
| 314 | struct page, lru); |
| 315 | list_del(&page->lru); |
| 316 | update_and_free_page(page); |
| 317 | free_huge_pages--; |
| 318 | free_huge_pages_node[nid]--; |
| 319 | surplus_huge_pages--; |
| 320 | surplus_huge_pages_node[nid]--; |
| 321 | nr_pages--; |
| 322 | } |
| 323 | } |
| 324 | } |
| 325 | |
| 326 | static struct page *alloc_huge_page(struct vm_area_struct *vma, |
| 327 | unsigned long addr) |
| 328 | { |
| 329 | struct page *page = NULL; |
| 330 | int use_reserved_page = vma->vm_flags & VM_MAYSHARE; |
| 331 | |
| 332 | spin_lock(&hugetlb_lock); |
| 333 | if (!use_reserved_page && (free_huge_pages <= resv_huge_pages)) |
| 334 | goto fail; |
| 335 | |
| 336 | page = dequeue_huge_page(vma, addr); |
| 337 | if (!page) |
| 338 | goto fail; |
| 339 | |
| 340 | spin_unlock(&hugetlb_lock); |
| 341 | set_page_refcounted(page); |
| 342 | return page; |
| 343 | |
| 344 | fail: |
| 345 | spin_unlock(&hugetlb_lock); |
| 346 | |
| 347 | /* |
| 348 | * Private mappings do not use reserved huge pages so the allocation |
| 349 | * may have failed due to an undersized hugetlb pool. Try to grab a |
| 350 | * surplus huge page from the buddy allocator. |
| 351 | */ |
| 352 | if (!use_reserved_page) |
| 353 | page = alloc_buddy_huge_page(vma, addr); |
| 354 | |
| 355 | return page; |
| 356 | } |
| 357 | |
| 358 | static int __init hugetlb_init(void) |
| 359 | { |
| 360 | unsigned long i; |
| 361 | |
| 362 | if (HPAGE_SHIFT == 0) |
| 363 | return 0; |
| 364 | |
| 365 | for (i = 0; i < MAX_NUMNODES; ++i) |
| 366 | INIT_LIST_HEAD(&hugepage_freelists[i]); |
| 367 | |
| 368 | for (i = 0; i < max_huge_pages; ++i) { |
| 369 | if (!alloc_fresh_huge_page()) |
| 370 | break; |
| 371 | } |
| 372 | max_huge_pages = free_huge_pages = nr_huge_pages = i; |
| 373 | printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages); |
| 374 | return 0; |
| 375 | } |
| 376 | module_init(hugetlb_init); |
| 377 | |
| 378 | static int __init hugetlb_setup(char *s) |
| 379 | { |
| 380 | if (sscanf(s, "%lu", &max_huge_pages) <= 0) |
| 381 | max_huge_pages = 0; |
| 382 | return 1; |
| 383 | } |
| 384 | __setup("hugepages=", hugetlb_setup); |
| 385 | |
| 386 | static unsigned int cpuset_mems_nr(unsigned int *array) |
| 387 | { |
| 388 | int node; |
| 389 | unsigned int nr = 0; |
| 390 | |
| 391 | for_each_node_mask(node, cpuset_current_mems_allowed) |
| 392 | nr += array[node]; |
| 393 | |
| 394 | return nr; |
| 395 | } |
| 396 | |
| 397 | #ifdef CONFIG_SYSCTL |
| 398 | #ifdef CONFIG_HIGHMEM |
| 399 | static void try_to_free_low(unsigned long count) |
| 400 | { |
| 401 | int i; |
| 402 | |
| 403 | for (i = 0; i < MAX_NUMNODES; ++i) { |
| 404 | struct page *page, *next; |
| 405 | list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) { |
| 406 | if (count >= nr_huge_pages) |
| 407 | return; |
| 408 | if (PageHighMem(page)) |
| 409 | continue; |
| 410 | list_del(&page->lru); |
| 411 | update_and_free_page(page); |
| 412 | free_huge_pages--; |
| 413 | free_huge_pages_node[page_to_nid(page)]--; |
| 414 | } |
| 415 | } |
| 416 | } |
| 417 | #else |
| 418 | static inline void try_to_free_low(unsigned long count) |
| 419 | { |
| 420 | } |
| 421 | #endif |
| 422 | |
| 423 | #define persistent_huge_pages (nr_huge_pages - surplus_huge_pages) |
| 424 | static unsigned long set_max_huge_pages(unsigned long count) |
| 425 | { |
| 426 | unsigned long min_count, ret; |
| 427 | |
| 428 | /* |
| 429 | * Increase the pool size |
| 430 | * First take pages out of surplus state. Then make up the |
| 431 | * remaining difference by allocating fresh huge pages. |
| 432 | */ |
| 433 | spin_lock(&hugetlb_lock); |
| 434 | while (surplus_huge_pages && count > persistent_huge_pages) { |
| 435 | if (!adjust_pool_surplus(-1)) |
| 436 | break; |
| 437 | } |
| 438 | |
| 439 | while (count > persistent_huge_pages) { |
| 440 | int ret; |
| 441 | /* |
| 442 | * If this allocation races such that we no longer need the |
| 443 | * page, free_huge_page will handle it by freeing the page |
| 444 | * and reducing the surplus. |
| 445 | */ |
| 446 | spin_unlock(&hugetlb_lock); |
| 447 | ret = alloc_fresh_huge_page(); |
| 448 | spin_lock(&hugetlb_lock); |
| 449 | if (!ret) |
| 450 | goto out; |
| 451 | |
| 452 | } |
| 453 | |
| 454 | /* |
| 455 | * Decrease the pool size |
| 456 | * First return free pages to the buddy allocator (being careful |
| 457 | * to keep enough around to satisfy reservations). Then place |
| 458 | * pages into surplus state as needed so the pool will shrink |
| 459 | * to the desired size as pages become free. |
| 460 | */ |
| 461 | min_count = resv_huge_pages + nr_huge_pages - free_huge_pages; |
| 462 | min_count = max(count, min_count); |
| 463 | try_to_free_low(min_count); |
| 464 | while (min_count < persistent_huge_pages) { |
| 465 | struct page *page = dequeue_huge_page(NULL, 0); |
| 466 | if (!page) |
| 467 | break; |
| 468 | update_and_free_page(page); |
| 469 | } |
| 470 | while (count < persistent_huge_pages) { |
| 471 | if (!adjust_pool_surplus(1)) |
| 472 | break; |
| 473 | } |
| 474 | out: |
| 475 | ret = persistent_huge_pages; |
| 476 | spin_unlock(&hugetlb_lock); |
| 477 | return ret; |
| 478 | } |
| 479 | |
| 480 | int hugetlb_sysctl_handler(struct ctl_table *table, int write, |
| 481 | struct file *file, void __user *buffer, |
| 482 | size_t *length, loff_t *ppos) |
| 483 | { |
| 484 | proc_doulongvec_minmax(table, write, file, buffer, length, ppos); |
| 485 | max_huge_pages = set_max_huge_pages(max_huge_pages); |
| 486 | return 0; |
| 487 | } |
| 488 | |
| 489 | int hugetlb_treat_movable_handler(struct ctl_table *table, int write, |
| 490 | struct file *file, void __user *buffer, |
| 491 | size_t *length, loff_t *ppos) |
| 492 | { |
| 493 | proc_dointvec(table, write, file, buffer, length, ppos); |
| 494 | if (hugepages_treat_as_movable) |
| 495 | htlb_alloc_mask = GFP_HIGHUSER_MOVABLE; |
| 496 | else |
| 497 | htlb_alloc_mask = GFP_HIGHUSER; |
| 498 | return 0; |
| 499 | } |
| 500 | |
| 501 | #endif /* CONFIG_SYSCTL */ |
| 502 | |
| 503 | int hugetlb_report_meminfo(char *buf) |
| 504 | { |
| 505 | return sprintf(buf, |
| 506 | "HugePages_Total: %5lu\n" |
| 507 | "HugePages_Free: %5lu\n" |
| 508 | "HugePages_Rsvd: %5lu\n" |
| 509 | "HugePages_Surp: %5lu\n" |
| 510 | "Hugepagesize: %5lu kB\n", |
| 511 | nr_huge_pages, |
| 512 | free_huge_pages, |
| 513 | resv_huge_pages, |
| 514 | surplus_huge_pages, |
| 515 | HPAGE_SIZE/1024); |
| 516 | } |
| 517 | |
| 518 | int hugetlb_report_node_meminfo(int nid, char *buf) |
| 519 | { |
| 520 | return sprintf(buf, |
| 521 | "Node %d HugePages_Total: %5u\n" |
| 522 | "Node %d HugePages_Free: %5u\n", |
| 523 | nid, nr_huge_pages_node[nid], |
| 524 | nid, free_huge_pages_node[nid]); |
| 525 | } |
| 526 | |
| 527 | /* Return the number pages of memory we physically have, in PAGE_SIZE units. */ |
| 528 | unsigned long hugetlb_total_pages(void) |
| 529 | { |
| 530 | return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE); |
| 531 | } |
| 532 | |
| 533 | /* |
| 534 | * We cannot handle pagefaults against hugetlb pages at all. They cause |
| 535 | * handle_mm_fault() to try to instantiate regular-sized pages in the |
| 536 | * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get |
| 537 | * this far. |
| 538 | */ |
| 539 | static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
| 540 | { |
| 541 | BUG(); |
| 542 | return 0; |
| 543 | } |
| 544 | |
| 545 | struct vm_operations_struct hugetlb_vm_ops = { |
| 546 | .fault = hugetlb_vm_op_fault, |
| 547 | }; |
| 548 | |
| 549 | static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page, |
| 550 | int writable) |
| 551 | { |
| 552 | pte_t entry; |
| 553 | |
| 554 | if (writable) { |
| 555 | entry = |
| 556 | pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot))); |
| 557 | } else { |
| 558 | entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot)); |
| 559 | } |
| 560 | entry = pte_mkyoung(entry); |
| 561 | entry = pte_mkhuge(entry); |
| 562 | |
| 563 | return entry; |
| 564 | } |
| 565 | |
| 566 | static void set_huge_ptep_writable(struct vm_area_struct *vma, |
| 567 | unsigned long address, pte_t *ptep) |
| 568 | { |
| 569 | pte_t entry; |
| 570 | |
| 571 | entry = pte_mkwrite(pte_mkdirty(*ptep)); |
| 572 | if (ptep_set_access_flags(vma, address, ptep, entry, 1)) { |
| 573 | update_mmu_cache(vma, address, entry); |
| 574 | } |
| 575 | } |
| 576 | |
| 577 | |
| 578 | int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, |
| 579 | struct vm_area_struct *vma) |
| 580 | { |
| 581 | pte_t *src_pte, *dst_pte, entry; |
| 582 | struct page *ptepage; |
| 583 | unsigned long addr; |
| 584 | int cow; |
| 585 | |
| 586 | cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; |
| 587 | |
| 588 | for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) { |
| 589 | src_pte = huge_pte_offset(src, addr); |
| 590 | if (!src_pte) |
| 591 | continue; |
| 592 | dst_pte = huge_pte_alloc(dst, addr); |
| 593 | if (!dst_pte) |
| 594 | goto nomem; |
| 595 | spin_lock(&dst->page_table_lock); |
| 596 | spin_lock(&src->page_table_lock); |
| 597 | if (!pte_none(*src_pte)) { |
| 598 | if (cow) |
| 599 | ptep_set_wrprotect(src, addr, src_pte); |
| 600 | entry = *src_pte; |
| 601 | ptepage = pte_page(entry); |
| 602 | get_page(ptepage); |
| 603 | set_huge_pte_at(dst, addr, dst_pte, entry); |
| 604 | } |
| 605 | spin_unlock(&src->page_table_lock); |
| 606 | spin_unlock(&dst->page_table_lock); |
| 607 | } |
| 608 | return 0; |
| 609 | |
| 610 | nomem: |
| 611 | return -ENOMEM; |
| 612 | } |
| 613 | |
| 614 | void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, |
| 615 | unsigned long end) |
| 616 | { |
| 617 | struct mm_struct *mm = vma->vm_mm; |
| 618 | unsigned long address; |
| 619 | pte_t *ptep; |
| 620 | pte_t pte; |
| 621 | struct page *page; |
| 622 | struct page *tmp; |
| 623 | /* |
| 624 | * A page gathering list, protected by per file i_mmap_lock. The |
| 625 | * lock is used to avoid list corruption from multiple unmapping |
| 626 | * of the same page since we are using page->lru. |
| 627 | */ |
| 628 | LIST_HEAD(page_list); |
| 629 | |
| 630 | WARN_ON(!is_vm_hugetlb_page(vma)); |
| 631 | BUG_ON(start & ~HPAGE_MASK); |
| 632 | BUG_ON(end & ~HPAGE_MASK); |
| 633 | |
| 634 | spin_lock(&mm->page_table_lock); |
| 635 | for (address = start; address < end; address += HPAGE_SIZE) { |
| 636 | ptep = huge_pte_offset(mm, address); |
| 637 | if (!ptep) |
| 638 | continue; |
| 639 | |
| 640 | if (huge_pmd_unshare(mm, &address, ptep)) |
| 641 | continue; |
| 642 | |
| 643 | pte = huge_ptep_get_and_clear(mm, address, ptep); |
| 644 | if (pte_none(pte)) |
| 645 | continue; |
| 646 | |
| 647 | page = pte_page(pte); |
| 648 | if (pte_dirty(pte)) |
| 649 | set_page_dirty(page); |
| 650 | list_add(&page->lru, &page_list); |
| 651 | } |
| 652 | spin_unlock(&mm->page_table_lock); |
| 653 | flush_tlb_range(vma, start, end); |
| 654 | list_for_each_entry_safe(page, tmp, &page_list, lru) { |
| 655 | list_del(&page->lru); |
| 656 | put_page(page); |
| 657 | } |
| 658 | } |
| 659 | |
| 660 | void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, |
| 661 | unsigned long end) |
| 662 | { |
| 663 | /* |
| 664 | * It is undesirable to test vma->vm_file as it should be non-null |
| 665 | * for valid hugetlb area. However, vm_file will be NULL in the error |
| 666 | * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails, |
| 667 | * do_mmap_pgoff() nullifies vma->vm_file before calling this function |
| 668 | * to clean up. Since no pte has actually been setup, it is safe to |
| 669 | * do nothing in this case. |
| 670 | */ |
| 671 | if (vma->vm_file) { |
| 672 | spin_lock(&vma->vm_file->f_mapping->i_mmap_lock); |
| 673 | __unmap_hugepage_range(vma, start, end); |
| 674 | spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); |
| 675 | } |
| 676 | } |
| 677 | |
| 678 | static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma, |
| 679 | unsigned long address, pte_t *ptep, pte_t pte) |
| 680 | { |
| 681 | struct page *old_page, *new_page; |
| 682 | int avoidcopy; |
| 683 | |
| 684 | old_page = pte_page(pte); |
| 685 | |
| 686 | /* If no-one else is actually using this page, avoid the copy |
| 687 | * and just make the page writable */ |
| 688 | avoidcopy = (page_count(old_page) == 1); |
| 689 | if (avoidcopy) { |
| 690 | set_huge_ptep_writable(vma, address, ptep); |
| 691 | return 0; |
| 692 | } |
| 693 | |
| 694 | page_cache_get(old_page); |
| 695 | new_page = alloc_huge_page(vma, address); |
| 696 | |
| 697 | if (!new_page) { |
| 698 | page_cache_release(old_page); |
| 699 | return VM_FAULT_OOM; |
| 700 | } |
| 701 | |
| 702 | spin_unlock(&mm->page_table_lock); |
| 703 | copy_huge_page(new_page, old_page, address, vma); |
| 704 | spin_lock(&mm->page_table_lock); |
| 705 | |
| 706 | ptep = huge_pte_offset(mm, address & HPAGE_MASK); |
| 707 | if (likely(pte_same(*ptep, pte))) { |
| 708 | /* Break COW */ |
| 709 | set_huge_pte_at(mm, address, ptep, |
| 710 | make_huge_pte(vma, new_page, 1)); |
| 711 | /* Make the old page be freed below */ |
| 712 | new_page = old_page; |
| 713 | } |
| 714 | page_cache_release(new_page); |
| 715 | page_cache_release(old_page); |
| 716 | return 0; |
| 717 | } |
| 718 | |
| 719 | static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, |
| 720 | unsigned long address, pte_t *ptep, int write_access) |
| 721 | { |
| 722 | int ret = VM_FAULT_SIGBUS; |
| 723 | unsigned long idx; |
| 724 | unsigned long size; |
| 725 | struct page *page; |
| 726 | struct address_space *mapping; |
| 727 | pte_t new_pte; |
| 728 | |
| 729 | mapping = vma->vm_file->f_mapping; |
| 730 | idx = ((address - vma->vm_start) >> HPAGE_SHIFT) |
| 731 | + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT)); |
| 732 | |
| 733 | /* |
| 734 | * Use page lock to guard against racing truncation |
| 735 | * before we get page_table_lock. |
| 736 | */ |
| 737 | retry: |
| 738 | page = find_lock_page(mapping, idx); |
| 739 | if (!page) { |
| 740 | size = i_size_read(mapping->host) >> HPAGE_SHIFT; |
| 741 | if (idx >= size) |
| 742 | goto out; |
| 743 | if (hugetlb_get_quota(mapping)) |
| 744 | goto out; |
| 745 | page = alloc_huge_page(vma, address); |
| 746 | if (!page) { |
| 747 | hugetlb_put_quota(mapping); |
| 748 | ret = VM_FAULT_OOM; |
| 749 | goto out; |
| 750 | } |
| 751 | clear_huge_page(page, address); |
| 752 | |
| 753 | if (vma->vm_flags & VM_SHARED) { |
| 754 | int err; |
| 755 | |
| 756 | err = add_to_page_cache(page, mapping, idx, GFP_KERNEL); |
| 757 | if (err) { |
| 758 | put_page(page); |
| 759 | hugetlb_put_quota(mapping); |
| 760 | if (err == -EEXIST) |
| 761 | goto retry; |
| 762 | goto out; |
| 763 | } |
| 764 | } else |
| 765 | lock_page(page); |
| 766 | } |
| 767 | |
| 768 | spin_lock(&mm->page_table_lock); |
| 769 | size = i_size_read(mapping->host) >> HPAGE_SHIFT; |
| 770 | if (idx >= size) |
| 771 | goto backout; |
| 772 | |
| 773 | ret = 0; |
| 774 | if (!pte_none(*ptep)) |
| 775 | goto backout; |
| 776 | |
| 777 | new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) |
| 778 | && (vma->vm_flags & VM_SHARED))); |
| 779 | set_huge_pte_at(mm, address, ptep, new_pte); |
| 780 | |
| 781 | if (write_access && !(vma->vm_flags & VM_SHARED)) { |
| 782 | /* Optimization, do the COW without a second fault */ |
| 783 | ret = hugetlb_cow(mm, vma, address, ptep, new_pte); |
| 784 | } |
| 785 | |
| 786 | spin_unlock(&mm->page_table_lock); |
| 787 | unlock_page(page); |
| 788 | out: |
| 789 | return ret; |
| 790 | |
| 791 | backout: |
| 792 | spin_unlock(&mm->page_table_lock); |
| 793 | hugetlb_put_quota(mapping); |
| 794 | unlock_page(page); |
| 795 | put_page(page); |
| 796 | goto out; |
| 797 | } |
| 798 | |
| 799 | int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, |
| 800 | unsigned long address, int write_access) |
| 801 | { |
| 802 | pte_t *ptep; |
| 803 | pte_t entry; |
| 804 | int ret; |
| 805 | static DEFINE_MUTEX(hugetlb_instantiation_mutex); |
| 806 | |
| 807 | ptep = huge_pte_alloc(mm, address); |
| 808 | if (!ptep) |
| 809 | return VM_FAULT_OOM; |
| 810 | |
| 811 | /* |
| 812 | * Serialize hugepage allocation and instantiation, so that we don't |
| 813 | * get spurious allocation failures if two CPUs race to instantiate |
| 814 | * the same page in the page cache. |
| 815 | */ |
| 816 | mutex_lock(&hugetlb_instantiation_mutex); |
| 817 | entry = *ptep; |
| 818 | if (pte_none(entry)) { |
| 819 | ret = hugetlb_no_page(mm, vma, address, ptep, write_access); |
| 820 | mutex_unlock(&hugetlb_instantiation_mutex); |
| 821 | return ret; |
| 822 | } |
| 823 | |
| 824 | ret = 0; |
| 825 | |
| 826 | spin_lock(&mm->page_table_lock); |
| 827 | /* Check for a racing update before calling hugetlb_cow */ |
| 828 | if (likely(pte_same(entry, *ptep))) |
| 829 | if (write_access && !pte_write(entry)) |
| 830 | ret = hugetlb_cow(mm, vma, address, ptep, entry); |
| 831 | spin_unlock(&mm->page_table_lock); |
| 832 | mutex_unlock(&hugetlb_instantiation_mutex); |
| 833 | |
| 834 | return ret; |
| 835 | } |
| 836 | |
| 837 | int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, |
| 838 | struct page **pages, struct vm_area_struct **vmas, |
| 839 | unsigned long *position, int *length, int i) |
| 840 | { |
| 841 | unsigned long pfn_offset; |
| 842 | unsigned long vaddr = *position; |
| 843 | int remainder = *length; |
| 844 | |
| 845 | spin_lock(&mm->page_table_lock); |
| 846 | while (vaddr < vma->vm_end && remainder) { |
| 847 | pte_t *pte; |
| 848 | struct page *page; |
| 849 | |
| 850 | /* |
| 851 | * Some archs (sparc64, sh*) have multiple pte_ts to |
| 852 | * each hugepage. We have to make * sure we get the |
| 853 | * first, for the page indexing below to work. |
| 854 | */ |
| 855 | pte = huge_pte_offset(mm, vaddr & HPAGE_MASK); |
| 856 | |
| 857 | if (!pte || pte_none(*pte)) { |
| 858 | int ret; |
| 859 | |
| 860 | spin_unlock(&mm->page_table_lock); |
| 861 | ret = hugetlb_fault(mm, vma, vaddr, 0); |
| 862 | spin_lock(&mm->page_table_lock); |
| 863 | if (!(ret & VM_FAULT_ERROR)) |
| 864 | continue; |
| 865 | |
| 866 | remainder = 0; |
| 867 | if (!i) |
| 868 | i = -EFAULT; |
| 869 | break; |
| 870 | } |
| 871 | |
| 872 | pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT; |
| 873 | page = pte_page(*pte); |
| 874 | same_page: |
| 875 | if (pages) { |
| 876 | get_page(page); |
| 877 | pages[i] = page + pfn_offset; |
| 878 | } |
| 879 | |
| 880 | if (vmas) |
| 881 | vmas[i] = vma; |
| 882 | |
| 883 | vaddr += PAGE_SIZE; |
| 884 | ++pfn_offset; |
| 885 | --remainder; |
| 886 | ++i; |
| 887 | if (vaddr < vma->vm_end && remainder && |
| 888 | pfn_offset < HPAGE_SIZE/PAGE_SIZE) { |
| 889 | /* |
| 890 | * We use pfn_offset to avoid touching the pageframes |
| 891 | * of this compound page. |
| 892 | */ |
| 893 | goto same_page; |
| 894 | } |
| 895 | } |
| 896 | spin_unlock(&mm->page_table_lock); |
| 897 | *length = remainder; |
| 898 | *position = vaddr; |
| 899 | |
| 900 | return i; |
| 901 | } |
| 902 | |
| 903 | void hugetlb_change_protection(struct vm_area_struct *vma, |
| 904 | unsigned long address, unsigned long end, pgprot_t newprot) |
| 905 | { |
| 906 | struct mm_struct *mm = vma->vm_mm; |
| 907 | unsigned long start = address; |
| 908 | pte_t *ptep; |
| 909 | pte_t pte; |
| 910 | |
| 911 | BUG_ON(address >= end); |
| 912 | flush_cache_range(vma, address, end); |
| 913 | |
| 914 | spin_lock(&vma->vm_file->f_mapping->i_mmap_lock); |
| 915 | spin_lock(&mm->page_table_lock); |
| 916 | for (; address < end; address += HPAGE_SIZE) { |
| 917 | ptep = huge_pte_offset(mm, address); |
| 918 | if (!ptep) |
| 919 | continue; |
| 920 | if (huge_pmd_unshare(mm, &address, ptep)) |
| 921 | continue; |
| 922 | if (!pte_none(*ptep)) { |
| 923 | pte = huge_ptep_get_and_clear(mm, address, ptep); |
| 924 | pte = pte_mkhuge(pte_modify(pte, newprot)); |
| 925 | set_huge_pte_at(mm, address, ptep, pte); |
| 926 | } |
| 927 | } |
| 928 | spin_unlock(&mm->page_table_lock); |
| 929 | spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock); |
| 930 | |
| 931 | flush_tlb_range(vma, start, end); |
| 932 | } |
| 933 | |
| 934 | struct file_region { |
| 935 | struct list_head link; |
| 936 | long from; |
| 937 | long to; |
| 938 | }; |
| 939 | |
| 940 | static long region_add(struct list_head *head, long f, long t) |
| 941 | { |
| 942 | struct file_region *rg, *nrg, *trg; |
| 943 | |
| 944 | /* Locate the region we are either in or before. */ |
| 945 | list_for_each_entry(rg, head, link) |
| 946 | if (f <= rg->to) |
| 947 | break; |
| 948 | |
| 949 | /* Round our left edge to the current segment if it encloses us. */ |
| 950 | if (f > rg->from) |
| 951 | f = rg->from; |
| 952 | |
| 953 | /* Check for and consume any regions we now overlap with. */ |
| 954 | nrg = rg; |
| 955 | list_for_each_entry_safe(rg, trg, rg->link.prev, link) { |
| 956 | if (&rg->link == head) |
| 957 | break; |
| 958 | if (rg->from > t) |
| 959 | break; |
| 960 | |
| 961 | /* If this area reaches higher then extend our area to |
| 962 | * include it completely. If this is not the first area |
| 963 | * which we intend to reuse, free it. */ |
| 964 | if (rg->to > t) |
| 965 | t = rg->to; |
| 966 | if (rg != nrg) { |
| 967 | list_del(&rg->link); |
| 968 | kfree(rg); |
| 969 | } |
| 970 | } |
| 971 | nrg->from = f; |
| 972 | nrg->to = t; |
| 973 | return 0; |
| 974 | } |
| 975 | |
| 976 | static long region_chg(struct list_head *head, long f, long t) |
| 977 | { |
| 978 | struct file_region *rg, *nrg; |
| 979 | long chg = 0; |
| 980 | |
| 981 | /* Locate the region we are before or in. */ |
| 982 | list_for_each_entry(rg, head, link) |
| 983 | if (f <= rg->to) |
| 984 | break; |
| 985 | |
| 986 | /* If we are below the current region then a new region is required. |
| 987 | * Subtle, allocate a new region at the position but make it zero |
| 988 | * size such that we can guarentee to record the reservation. */ |
| 989 | if (&rg->link == head || t < rg->from) { |
| 990 | nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); |
| 991 | if (nrg == 0) |
| 992 | return -ENOMEM; |
| 993 | nrg->from = f; |
| 994 | nrg->to = f; |
| 995 | INIT_LIST_HEAD(&nrg->link); |
| 996 | list_add(&nrg->link, rg->link.prev); |
| 997 | |
| 998 | return t - f; |
| 999 | } |
| 1000 | |
| 1001 | /* Round our left edge to the current segment if it encloses us. */ |
| 1002 | if (f > rg->from) |
| 1003 | f = rg->from; |
| 1004 | chg = t - f; |
| 1005 | |
| 1006 | /* Check for and consume any regions we now overlap with. */ |
| 1007 | list_for_each_entry(rg, rg->link.prev, link) { |
| 1008 | if (&rg->link == head) |
| 1009 | break; |
| 1010 | if (rg->from > t) |
| 1011 | return chg; |
| 1012 | |
| 1013 | /* We overlap with this area, if it extends futher than |
| 1014 | * us then we must extend ourselves. Account for its |
| 1015 | * existing reservation. */ |
| 1016 | if (rg->to > t) { |
| 1017 | chg += rg->to - t; |
| 1018 | t = rg->to; |
| 1019 | } |
| 1020 | chg -= rg->to - rg->from; |
| 1021 | } |
| 1022 | return chg; |
| 1023 | } |
| 1024 | |
| 1025 | static long region_truncate(struct list_head *head, long end) |
| 1026 | { |
| 1027 | struct file_region *rg, *trg; |
| 1028 | long chg = 0; |
| 1029 | |
| 1030 | /* Locate the region we are either in or before. */ |
| 1031 | list_for_each_entry(rg, head, link) |
| 1032 | if (end <= rg->to) |
| 1033 | break; |
| 1034 | if (&rg->link == head) |
| 1035 | return 0; |
| 1036 | |
| 1037 | /* If we are in the middle of a region then adjust it. */ |
| 1038 | if (end > rg->from) { |
| 1039 | chg = rg->to - end; |
| 1040 | rg->to = end; |
| 1041 | rg = list_entry(rg->link.next, typeof(*rg), link); |
| 1042 | } |
| 1043 | |
| 1044 | /* Drop any remaining regions. */ |
| 1045 | list_for_each_entry_safe(rg, trg, rg->link.prev, link) { |
| 1046 | if (&rg->link == head) |
| 1047 | break; |
| 1048 | chg += rg->to - rg->from; |
| 1049 | list_del(&rg->link); |
| 1050 | kfree(rg); |
| 1051 | } |
| 1052 | return chg; |
| 1053 | } |
| 1054 | |
| 1055 | static int hugetlb_acct_memory(long delta) |
| 1056 | { |
| 1057 | int ret = -ENOMEM; |
| 1058 | |
| 1059 | spin_lock(&hugetlb_lock); |
| 1060 | /* |
| 1061 | * When cpuset is configured, it breaks the strict hugetlb page |
| 1062 | * reservation as the accounting is done on a global variable. Such |
| 1063 | * reservation is completely rubbish in the presence of cpuset because |
| 1064 | * the reservation is not checked against page availability for the |
| 1065 | * current cpuset. Application can still potentially OOM'ed by kernel |
| 1066 | * with lack of free htlb page in cpuset that the task is in. |
| 1067 | * Attempt to enforce strict accounting with cpuset is almost |
| 1068 | * impossible (or too ugly) because cpuset is too fluid that |
| 1069 | * task or memory node can be dynamically moved between cpusets. |
| 1070 | * |
| 1071 | * The change of semantics for shared hugetlb mapping with cpuset is |
| 1072 | * undesirable. However, in order to preserve some of the semantics, |
| 1073 | * we fall back to check against current free page availability as |
| 1074 | * a best attempt and hopefully to minimize the impact of changing |
| 1075 | * semantics that cpuset has. |
| 1076 | */ |
| 1077 | if (delta > 0) { |
| 1078 | if (gather_surplus_pages(delta) < 0) |
| 1079 | goto out; |
| 1080 | |
| 1081 | if (delta > cpuset_mems_nr(free_huge_pages_node)) |
| 1082 | goto out; |
| 1083 | } |
| 1084 | |
| 1085 | ret = 0; |
| 1086 | resv_huge_pages += delta; |
| 1087 | if (delta < 0) |
| 1088 | return_unused_surplus_pages((unsigned long) -delta); |
| 1089 | |
| 1090 | out: |
| 1091 | spin_unlock(&hugetlb_lock); |
| 1092 | return ret; |
| 1093 | } |
| 1094 | |
| 1095 | int hugetlb_reserve_pages(struct inode *inode, long from, long to) |
| 1096 | { |
| 1097 | long ret, chg; |
| 1098 | |
| 1099 | chg = region_chg(&inode->i_mapping->private_list, from, to); |
| 1100 | if (chg < 0) |
| 1101 | return chg; |
| 1102 | |
| 1103 | ret = hugetlb_acct_memory(chg); |
| 1104 | if (ret < 0) |
| 1105 | return ret; |
| 1106 | region_add(&inode->i_mapping->private_list, from, to); |
| 1107 | return 0; |
| 1108 | } |
| 1109 | |
| 1110 | void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed) |
| 1111 | { |
| 1112 | long chg = region_truncate(&inode->i_mapping->private_list, offset); |
| 1113 | hugetlb_acct_memory(freed - chg); |
| 1114 | } |