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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/seq_file.h>
11 #include <linux/sysctl.h>
12 #include <linux/highmem.h>
13 #include <linux/mmu_notifier.h>
14 #include <linux/nodemask.h>
15 #include <linux/pagemap.h>
16 #include <linux/mempolicy.h>
17 #include <linux/cpuset.h>
18 #include <linux/mutex.h>
19 #include <linux/bootmem.h>
20 #include <linux/sysfs.h>
21
22 #include <asm/page.h>
23 #include <asm/pgtable.h>
24 #include <asm/io.h>
25
26 #include <linux/hugetlb.h>
27 #include "internal.h"
28
29 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
30 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
31 unsigned long hugepages_treat_as_movable;
32
33 static int max_hstate;
34 unsigned int default_hstate_idx;
35 struct hstate hstates[HUGE_MAX_HSTATE];
36
37 __initdata LIST_HEAD(huge_boot_pages);
38
39 /* for command line parsing */
40 static struct hstate * __initdata parsed_hstate;
41 static unsigned long __initdata default_hstate_max_huge_pages;
42 static unsigned long __initdata default_hstate_size;
43
44 #define for_each_hstate(h) \
45 for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++)
46
47 /*
48 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
49 */
50 static DEFINE_SPINLOCK(hugetlb_lock);
51
52 /*
53 * Region tracking -- allows tracking of reservations and instantiated pages
54 * across the pages in a mapping.
55 *
56 * The region data structures are protected by a combination of the mmap_sem
57 * and the hugetlb_instantion_mutex. To access or modify a region the caller
58 * must either hold the mmap_sem for write, or the mmap_sem for read and
59 * the hugetlb_instantiation mutex:
60 *
61 * down_write(&mm->mmap_sem);
62 * or
63 * down_read(&mm->mmap_sem);
64 * mutex_lock(&hugetlb_instantiation_mutex);
65 */
66 struct file_region {
67 struct list_head link;
68 long from;
69 long to;
70 };
71
72 static long region_add(struct list_head *head, long f, long t)
73 {
74 struct file_region *rg, *nrg, *trg;
75
76 /* Locate the region we are either in or before. */
77 list_for_each_entry(rg, head, link)
78 if (f <= rg->to)
79 break;
80
81 /* Round our left edge to the current segment if it encloses us. */
82 if (f > rg->from)
83 f = rg->from;
84
85 /* Check for and consume any regions we now overlap with. */
86 nrg = rg;
87 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
88 if (&rg->link == head)
89 break;
90 if (rg->from > t)
91 break;
92
93 /* If this area reaches higher then extend our area to
94 * include it completely. If this is not the first area
95 * which we intend to reuse, free it. */
96 if (rg->to > t)
97 t = rg->to;
98 if (rg != nrg) {
99 list_del(&rg->link);
100 kfree(rg);
101 }
102 }
103 nrg->from = f;
104 nrg->to = t;
105 return 0;
106 }
107
108 static long region_chg(struct list_head *head, long f, long t)
109 {
110 struct file_region *rg, *nrg;
111 long chg = 0;
112
113 /* Locate the region we are before or in. */
114 list_for_each_entry(rg, head, link)
115 if (f <= rg->to)
116 break;
117
118 /* If we are below the current region then a new region is required.
119 * Subtle, allocate a new region at the position but make it zero
120 * size such that we can guarantee to record the reservation. */
121 if (&rg->link == head || t < rg->from) {
122 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
123 if (!nrg)
124 return -ENOMEM;
125 nrg->from = f;
126 nrg->to = f;
127 INIT_LIST_HEAD(&nrg->link);
128 list_add(&nrg->link, rg->link.prev);
129
130 return t - f;
131 }
132
133 /* Round our left edge to the current segment if it encloses us. */
134 if (f > rg->from)
135 f = rg->from;
136 chg = t - f;
137
138 /* Check for and consume any regions we now overlap with. */
139 list_for_each_entry(rg, rg->link.prev, link) {
140 if (&rg->link == head)
141 break;
142 if (rg->from > t)
143 return chg;
144
145 /* We overlap with this area, if it extends futher than
146 * us then we must extend ourselves. Account for its
147 * existing reservation. */
148 if (rg->to > t) {
149 chg += rg->to - t;
150 t = rg->to;
151 }
152 chg -= rg->to - rg->from;
153 }
154 return chg;
155 }
156
157 static long region_truncate(struct list_head *head, long end)
158 {
159 struct file_region *rg, *trg;
160 long chg = 0;
161
162 /* Locate the region we are either in or before. */
163 list_for_each_entry(rg, head, link)
164 if (end <= rg->to)
165 break;
166 if (&rg->link == head)
167 return 0;
168
169 /* If we are in the middle of a region then adjust it. */
170 if (end > rg->from) {
171 chg = rg->to - end;
172 rg->to = end;
173 rg = list_entry(rg->link.next, typeof(*rg), link);
174 }
175
176 /* Drop any remaining regions. */
177 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
178 if (&rg->link == head)
179 break;
180 chg += rg->to - rg->from;
181 list_del(&rg->link);
182 kfree(rg);
183 }
184 return chg;
185 }
186
187 static long region_count(struct list_head *head, long f, long t)
188 {
189 struct file_region *rg;
190 long chg = 0;
191
192 /* Locate each segment we overlap with, and count that overlap. */
193 list_for_each_entry(rg, head, link) {
194 int seg_from;
195 int seg_to;
196
197 if (rg->to <= f)
198 continue;
199 if (rg->from >= t)
200 break;
201
202 seg_from = max(rg->from, f);
203 seg_to = min(rg->to, t);
204
205 chg += seg_to - seg_from;
206 }
207
208 return chg;
209 }
210
211 /*
212 * Convert the address within this vma to the page offset within
213 * the mapping, in pagecache page units; huge pages here.
214 */
215 static pgoff_t vma_hugecache_offset(struct hstate *h,
216 struct vm_area_struct *vma, unsigned long address)
217 {
218 return ((address - vma->vm_start) >> huge_page_shift(h)) +
219 (vma->vm_pgoff >> huge_page_order(h));
220 }
221
222 /*
223 * Return the size of the pages allocated when backing a VMA. In the majority
224 * cases this will be same size as used by the page table entries.
225 */
226 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
227 {
228 struct hstate *hstate;
229
230 if (!is_vm_hugetlb_page(vma))
231 return PAGE_SIZE;
232
233 hstate = hstate_vma(vma);
234
235 return 1UL << (hstate->order + PAGE_SHIFT);
236 }
237
238 /*
239 * Return the page size being used by the MMU to back a VMA. In the majority
240 * of cases, the page size used by the kernel matches the MMU size. On
241 * architectures where it differs, an architecture-specific version of this
242 * function is required.
243 */
244 #ifndef vma_mmu_pagesize
245 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
246 {
247 return vma_kernel_pagesize(vma);
248 }
249 #endif
250
251 /*
252 * Flags for MAP_PRIVATE reservations. These are stored in the bottom
253 * bits of the reservation map pointer, which are always clear due to
254 * alignment.
255 */
256 #define HPAGE_RESV_OWNER (1UL << 0)
257 #define HPAGE_RESV_UNMAPPED (1UL << 1)
258 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
259
260 /*
261 * These helpers are used to track how many pages are reserved for
262 * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
263 * is guaranteed to have their future faults succeed.
264 *
265 * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
266 * the reserve counters are updated with the hugetlb_lock held. It is safe
267 * to reset the VMA at fork() time as it is not in use yet and there is no
268 * chance of the global counters getting corrupted as a result of the values.
269 *
270 * The private mapping reservation is represented in a subtly different
271 * manner to a shared mapping. A shared mapping has a region map associated
272 * with the underlying file, this region map represents the backing file
273 * pages which have ever had a reservation assigned which this persists even
274 * after the page is instantiated. A private mapping has a region map
275 * associated with the original mmap which is attached to all VMAs which
276 * reference it, this region map represents those offsets which have consumed
277 * reservation ie. where pages have been instantiated.
278 */
279 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
280 {
281 return (unsigned long)vma->vm_private_data;
282 }
283
284 static void set_vma_private_data(struct vm_area_struct *vma,
285 unsigned long value)
286 {
287 vma->vm_private_data = (void *)value;
288 }
289
290 struct resv_map {
291 struct kref refs;
292 struct list_head regions;
293 };
294
295 static struct resv_map *resv_map_alloc(void)
296 {
297 struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
298 if (!resv_map)
299 return NULL;
300
301 kref_init(&resv_map->refs);
302 INIT_LIST_HEAD(&resv_map->regions);
303
304 return resv_map;
305 }
306
307 static void resv_map_release(struct kref *ref)
308 {
309 struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
310
311 /* Clear out any active regions before we release the map. */
312 region_truncate(&resv_map->regions, 0);
313 kfree(resv_map);
314 }
315
316 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
317 {
318 VM_BUG_ON(!is_vm_hugetlb_page(vma));
319 if (!(vma->vm_flags & VM_MAYSHARE))
320 return (struct resv_map *)(get_vma_private_data(vma) &
321 ~HPAGE_RESV_MASK);
322 return NULL;
323 }
324
325 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
326 {
327 VM_BUG_ON(!is_vm_hugetlb_page(vma));
328 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
329
330 set_vma_private_data(vma, (get_vma_private_data(vma) &
331 HPAGE_RESV_MASK) | (unsigned long)map);
332 }
333
334 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
335 {
336 VM_BUG_ON(!is_vm_hugetlb_page(vma));
337 VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
338
339 set_vma_private_data(vma, get_vma_private_data(vma) | flags);
340 }
341
342 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
343 {
344 VM_BUG_ON(!is_vm_hugetlb_page(vma));
345
346 return (get_vma_private_data(vma) & flag) != 0;
347 }
348
349 /* Decrement the reserved pages in the hugepage pool by one */
350 static void decrement_hugepage_resv_vma(struct hstate *h,
351 struct vm_area_struct *vma)
352 {
353 if (vma->vm_flags & VM_NORESERVE)
354 return;
355
356 if (vma->vm_flags & VM_MAYSHARE) {
357 /* Shared mappings always use reserves */
358 h->resv_huge_pages--;
359 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
360 /*
361 * Only the process that called mmap() has reserves for
362 * private mappings.
363 */
364 h->resv_huge_pages--;
365 }
366 }
367
368 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
369 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
370 {
371 VM_BUG_ON(!is_vm_hugetlb_page(vma));
372 if (!(vma->vm_flags & VM_MAYSHARE))
373 vma->vm_private_data = (void *)0;
374 }
375
376 /* Returns true if the VMA has associated reserve pages */
377 static int vma_has_reserves(struct vm_area_struct *vma)
378 {
379 if (vma->vm_flags & VM_MAYSHARE)
380 return 1;
381 if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
382 return 1;
383 return 0;
384 }
385
386 static void clear_gigantic_page(struct page *page,
387 unsigned long addr, unsigned long sz)
388 {
389 int i;
390 struct page *p = page;
391
392 might_sleep();
393 for (i = 0; i < sz/PAGE_SIZE; i++, p = mem_map_next(p, page, i)) {
394 cond_resched();
395 clear_user_highpage(p, addr + i * PAGE_SIZE);
396 }
397 }
398 static void clear_huge_page(struct page *page,
399 unsigned long addr, unsigned long sz)
400 {
401 int i;
402
403 if (unlikely(sz > MAX_ORDER_NR_PAGES)) {
404 clear_gigantic_page(page, addr, sz);
405 return;
406 }
407
408 might_sleep();
409 for (i = 0; i < sz/PAGE_SIZE; i++) {
410 cond_resched();
411 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
412 }
413 }
414
415 static void copy_gigantic_page(struct page *dst, struct page *src,
416 unsigned long addr, struct vm_area_struct *vma)
417 {
418 int i;
419 struct hstate *h = hstate_vma(vma);
420 struct page *dst_base = dst;
421 struct page *src_base = src;
422 might_sleep();
423 for (i = 0; i < pages_per_huge_page(h); ) {
424 cond_resched();
425 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
426
427 i++;
428 dst = mem_map_next(dst, dst_base, i);
429 src = mem_map_next(src, src_base, i);
430 }
431 }
432 static void copy_huge_page(struct page *dst, struct page *src,
433 unsigned long addr, struct vm_area_struct *vma)
434 {
435 int i;
436 struct hstate *h = hstate_vma(vma);
437
438 if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
439 copy_gigantic_page(dst, src, addr, vma);
440 return;
441 }
442
443 might_sleep();
444 for (i = 0; i < pages_per_huge_page(h); i++) {
445 cond_resched();
446 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
447 }
448 }
449
450 static void enqueue_huge_page(struct hstate *h, struct page *page)
451 {
452 int nid = page_to_nid(page);
453 list_add(&page->lru, &h->hugepage_freelists[nid]);
454 h->free_huge_pages++;
455 h->free_huge_pages_node[nid]++;
456 }
457
458 static struct page *dequeue_huge_page(struct hstate *h)
459 {
460 int nid;
461 struct page *page = NULL;
462
463 for (nid = 0; nid < MAX_NUMNODES; ++nid) {
464 if (!list_empty(&h->hugepage_freelists[nid])) {
465 page = list_entry(h->hugepage_freelists[nid].next,
466 struct page, lru);
467 list_del(&page->lru);
468 h->free_huge_pages--;
469 h->free_huge_pages_node[nid]--;
470 break;
471 }
472 }
473 return page;
474 }
475
476 static struct page *dequeue_huge_page_vma(struct hstate *h,
477 struct vm_area_struct *vma,
478 unsigned long address, int avoid_reserve)
479 {
480 int nid;
481 struct page *page = NULL;
482 struct mempolicy *mpol;
483 nodemask_t *nodemask;
484 struct zonelist *zonelist = huge_zonelist(vma, address,
485 htlb_alloc_mask, &mpol, &nodemask);
486 struct zone *zone;
487 struct zoneref *z;
488
489 /*
490 * A child process with MAP_PRIVATE mappings created by their parent
491 * have no page reserves. This check ensures that reservations are
492 * not "stolen". The child may still get SIGKILLed
493 */
494 if (!vma_has_reserves(vma) &&
495 h->free_huge_pages - h->resv_huge_pages == 0)
496 return NULL;
497
498 /* If reserves cannot be used, ensure enough pages are in the pool */
499 if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
500 return NULL;
501
502 for_each_zone_zonelist_nodemask(zone, z, zonelist,
503 MAX_NR_ZONES - 1, nodemask) {
504 nid = zone_to_nid(zone);
505 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
506 !list_empty(&h->hugepage_freelists[nid])) {
507 page = list_entry(h->hugepage_freelists[nid].next,
508 struct page, lru);
509 list_del(&page->lru);
510 h->free_huge_pages--;
511 h->free_huge_pages_node[nid]--;
512
513 if (!avoid_reserve)
514 decrement_hugepage_resv_vma(h, vma);
515
516 break;
517 }
518 }
519 mpol_cond_put(mpol);
520 return page;
521 }
522
523 static void update_and_free_page(struct hstate *h, struct page *page)
524 {
525 int i;
526
527 VM_BUG_ON(h->order >= MAX_ORDER);
528
529 h->nr_huge_pages--;
530 h->nr_huge_pages_node[page_to_nid(page)]--;
531 for (i = 0; i < pages_per_huge_page(h); i++) {
532 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
533 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
534 1 << PG_private | 1<< PG_writeback);
535 }
536 set_compound_page_dtor(page, NULL);
537 set_page_refcounted(page);
538 arch_release_hugepage(page);
539 __free_pages(page, huge_page_order(h));
540 }
541
542 struct hstate *size_to_hstate(unsigned long size)
543 {
544 struct hstate *h;
545
546 for_each_hstate(h) {
547 if (huge_page_size(h) == size)
548 return h;
549 }
550 return NULL;
551 }
552
553 static void free_huge_page(struct page *page)
554 {
555 /*
556 * Can't pass hstate in here because it is called from the
557 * compound page destructor.
558 */
559 struct hstate *h = page_hstate(page);
560 int nid = page_to_nid(page);
561 struct address_space *mapping;
562
563 mapping = (struct address_space *) page_private(page);
564 set_page_private(page, 0);
565 BUG_ON(page_count(page));
566 INIT_LIST_HEAD(&page->lru);
567
568 spin_lock(&hugetlb_lock);
569 if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
570 update_and_free_page(h, page);
571 h->surplus_huge_pages--;
572 h->surplus_huge_pages_node[nid]--;
573 } else {
574 enqueue_huge_page(h, page);
575 }
576 spin_unlock(&hugetlb_lock);
577 if (mapping)
578 hugetlb_put_quota(mapping, 1);
579 }
580
581 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
582 {
583 set_compound_page_dtor(page, free_huge_page);
584 spin_lock(&hugetlb_lock);
585 h->nr_huge_pages++;
586 h->nr_huge_pages_node[nid]++;
587 spin_unlock(&hugetlb_lock);
588 put_page(page); /* free it into the hugepage allocator */
589 }
590
591 static void prep_compound_gigantic_page(struct page *page, unsigned long order)
592 {
593 int i;
594 int nr_pages = 1 << order;
595 struct page *p = page + 1;
596
597 /* we rely on prep_new_huge_page to set the destructor */
598 set_compound_order(page, order);
599 __SetPageHead(page);
600 for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
601 __SetPageTail(p);
602 p->first_page = page;
603 }
604 }
605
606 int PageHuge(struct page *page)
607 {
608 compound_page_dtor *dtor;
609
610 if (!PageCompound(page))
611 return 0;
612
613 page = compound_head(page);
614 dtor = get_compound_page_dtor(page);
615
616 return dtor == free_huge_page;
617 }
618
619 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
620 {
621 struct page *page;
622
623 if (h->order >= MAX_ORDER)
624 return NULL;
625
626 page = alloc_pages_exact_node(nid,
627 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
628 __GFP_REPEAT|__GFP_NOWARN,
629 huge_page_order(h));
630 if (page) {
631 if (arch_prepare_hugepage(page)) {
632 __free_pages(page, huge_page_order(h));
633 return NULL;
634 }
635 prep_new_huge_page(h, page, nid);
636 }
637
638 return page;
639 }
640
641 /*
642 * Use a helper variable to find the next node and then
643 * copy it back to hugetlb_next_nid afterwards:
644 * otherwise there's a window in which a racer might
645 * pass invalid nid MAX_NUMNODES to alloc_pages_exact_node.
646 * But we don't need to use a spin_lock here: it really
647 * doesn't matter if occasionally a racer chooses the
648 * same nid as we do. Move nid forward in the mask even
649 * if we just successfully allocated a hugepage so that
650 * the next caller gets hugepages on the next node.
651 */
652 static int hstate_next_node(struct hstate *h)
653 {
654 int next_nid;
655 next_nid = next_node(h->hugetlb_next_nid, node_online_map);
656 if (next_nid == MAX_NUMNODES)
657 next_nid = first_node(node_online_map);
658 h->hugetlb_next_nid = next_nid;
659 return next_nid;
660 }
661
662 static int alloc_fresh_huge_page(struct hstate *h)
663 {
664 struct page *page;
665 int start_nid;
666 int next_nid;
667 int ret = 0;
668
669 start_nid = h->hugetlb_next_nid;
670
671 do {
672 page = alloc_fresh_huge_page_node(h, h->hugetlb_next_nid);
673 if (page)
674 ret = 1;
675 next_nid = hstate_next_node(h);
676 } while (!page && h->hugetlb_next_nid != start_nid);
677
678 if (ret)
679 count_vm_event(HTLB_BUDDY_PGALLOC);
680 else
681 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
682
683 return ret;
684 }
685
686 static struct page *alloc_buddy_huge_page(struct hstate *h,
687 struct vm_area_struct *vma, unsigned long address)
688 {
689 struct page *page;
690 unsigned int nid;
691
692 if (h->order >= MAX_ORDER)
693 return NULL;
694
695 /*
696 * Assume we will successfully allocate the surplus page to
697 * prevent racing processes from causing the surplus to exceed
698 * overcommit
699 *
700 * This however introduces a different race, where a process B
701 * tries to grow the static hugepage pool while alloc_pages() is
702 * called by process A. B will only examine the per-node
703 * counters in determining if surplus huge pages can be
704 * converted to normal huge pages in adjust_pool_surplus(). A
705 * won't be able to increment the per-node counter, until the
706 * lock is dropped by B, but B doesn't drop hugetlb_lock until
707 * no more huge pages can be converted from surplus to normal
708 * state (and doesn't try to convert again). Thus, we have a
709 * case where a surplus huge page exists, the pool is grown, and
710 * the surplus huge page still exists after, even though it
711 * should just have been converted to a normal huge page. This
712 * does not leak memory, though, as the hugepage will be freed
713 * once it is out of use. It also does not allow the counters to
714 * go out of whack in adjust_pool_surplus() as we don't modify
715 * the node values until we've gotten the hugepage and only the
716 * per-node value is checked there.
717 */
718 spin_lock(&hugetlb_lock);
719 if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
720 spin_unlock(&hugetlb_lock);
721 return NULL;
722 } else {
723 h->nr_huge_pages++;
724 h->surplus_huge_pages++;
725 }
726 spin_unlock(&hugetlb_lock);
727
728 page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
729 __GFP_REPEAT|__GFP_NOWARN,
730 huge_page_order(h));
731
732 if (page && arch_prepare_hugepage(page)) {
733 __free_pages(page, huge_page_order(h));
734 return NULL;
735 }
736
737 spin_lock(&hugetlb_lock);
738 if (page) {
739 /*
740 * This page is now managed by the hugetlb allocator and has
741 * no users -- drop the buddy allocator's reference.
742 */
743 put_page_testzero(page);
744 VM_BUG_ON(page_count(page));
745 nid = page_to_nid(page);
746 set_compound_page_dtor(page, free_huge_page);
747 /*
748 * We incremented the global counters already
749 */
750 h->nr_huge_pages_node[nid]++;
751 h->surplus_huge_pages_node[nid]++;
752 __count_vm_event(HTLB_BUDDY_PGALLOC);
753 } else {
754 h->nr_huge_pages--;
755 h->surplus_huge_pages--;
756 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
757 }
758 spin_unlock(&hugetlb_lock);
759
760 return page;
761 }
762
763 /*
764 * Increase the hugetlb pool such that it can accomodate a reservation
765 * of size 'delta'.
766 */
767 static int gather_surplus_pages(struct hstate *h, int delta)
768 {
769 struct list_head surplus_list;
770 struct page *page, *tmp;
771 int ret, i;
772 int needed, allocated;
773
774 needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
775 if (needed <= 0) {
776 h->resv_huge_pages += delta;
777 return 0;
778 }
779
780 allocated = 0;
781 INIT_LIST_HEAD(&surplus_list);
782
783 ret = -ENOMEM;
784 retry:
785 spin_unlock(&hugetlb_lock);
786 for (i = 0; i < needed; i++) {
787 page = alloc_buddy_huge_page(h, NULL, 0);
788 if (!page) {
789 /*
790 * We were not able to allocate enough pages to
791 * satisfy the entire reservation so we free what
792 * we've allocated so far.
793 */
794 spin_lock(&hugetlb_lock);
795 needed = 0;
796 goto free;
797 }
798
799 list_add(&page->lru, &surplus_list);
800 }
801 allocated += needed;
802
803 /*
804 * After retaking hugetlb_lock, we need to recalculate 'needed'
805 * because either resv_huge_pages or free_huge_pages may have changed.
806 */
807 spin_lock(&hugetlb_lock);
808 needed = (h->resv_huge_pages + delta) -
809 (h->free_huge_pages + allocated);
810 if (needed > 0)
811 goto retry;
812
813 /*
814 * The surplus_list now contains _at_least_ the number of extra pages
815 * needed to accomodate the reservation. Add the appropriate number
816 * of pages to the hugetlb pool and free the extras back to the buddy
817 * allocator. Commit the entire reservation here to prevent another
818 * process from stealing the pages as they are added to the pool but
819 * before they are reserved.
820 */
821 needed += allocated;
822 h->resv_huge_pages += delta;
823 ret = 0;
824 free:
825 /* Free the needed pages to the hugetlb pool */
826 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
827 if ((--needed) < 0)
828 break;
829 list_del(&page->lru);
830 enqueue_huge_page(h, page);
831 }
832
833 /* Free unnecessary surplus pages to the buddy allocator */
834 if (!list_empty(&surplus_list)) {
835 spin_unlock(&hugetlb_lock);
836 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
837 list_del(&page->lru);
838 /*
839 * The page has a reference count of zero already, so
840 * call free_huge_page directly instead of using
841 * put_page. This must be done with hugetlb_lock
842 * unlocked which is safe because free_huge_page takes
843 * hugetlb_lock before deciding how to free the page.
844 */
845 free_huge_page(page);
846 }
847 spin_lock(&hugetlb_lock);
848 }
849
850 return ret;
851 }
852
853 /*
854 * When releasing a hugetlb pool reservation, any surplus pages that were
855 * allocated to satisfy the reservation must be explicitly freed if they were
856 * never used.
857 */
858 static void return_unused_surplus_pages(struct hstate *h,
859 unsigned long unused_resv_pages)
860 {
861 static int nid = -1;
862 struct page *page;
863 unsigned long nr_pages;
864
865 /*
866 * We want to release as many surplus pages as possible, spread
867 * evenly across all nodes. Iterate across all nodes until we
868 * can no longer free unreserved surplus pages. This occurs when
869 * the nodes with surplus pages have no free pages.
870 */
871 unsigned long remaining_iterations = nr_online_nodes;
872
873 /* Uncommit the reservation */
874 h->resv_huge_pages -= unused_resv_pages;
875
876 /* Cannot return gigantic pages currently */
877 if (h->order >= MAX_ORDER)
878 return;
879
880 nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
881
882 while (remaining_iterations-- && nr_pages) {
883 nid = next_node(nid, node_online_map);
884 if (nid == MAX_NUMNODES)
885 nid = first_node(node_online_map);
886
887 if (!h->surplus_huge_pages_node[nid])
888 continue;
889
890 if (!list_empty(&h->hugepage_freelists[nid])) {
891 page = list_entry(h->hugepage_freelists[nid].next,
892 struct page, lru);
893 list_del(&page->lru);
894 update_and_free_page(h, page);
895 h->free_huge_pages--;
896 h->free_huge_pages_node[nid]--;
897 h->surplus_huge_pages--;
898 h->surplus_huge_pages_node[nid]--;
899 nr_pages--;
900 remaining_iterations = nr_online_nodes;
901 }
902 }
903 }
904
905 /*
906 * Determine if the huge page at addr within the vma has an associated
907 * reservation. Where it does not we will need to logically increase
908 * reservation and actually increase quota before an allocation can occur.
909 * Where any new reservation would be required the reservation change is
910 * prepared, but not committed. Once the page has been quota'd allocated
911 * an instantiated the change should be committed via vma_commit_reservation.
912 * No action is required on failure.
913 */
914 static long vma_needs_reservation(struct hstate *h,
915 struct vm_area_struct *vma, unsigned long addr)
916 {
917 struct address_space *mapping = vma->vm_file->f_mapping;
918 struct inode *inode = mapping->host;
919
920 if (vma->vm_flags & VM_MAYSHARE) {
921 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
922 return region_chg(&inode->i_mapping->private_list,
923 idx, idx + 1);
924
925 } else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
926 return 1;
927
928 } else {
929 long err;
930 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
931 struct resv_map *reservations = vma_resv_map(vma);
932
933 err = region_chg(&reservations->regions, idx, idx + 1);
934 if (err < 0)
935 return err;
936 return 0;
937 }
938 }
939 static void vma_commit_reservation(struct hstate *h,
940 struct vm_area_struct *vma, unsigned long addr)
941 {
942 struct address_space *mapping = vma->vm_file->f_mapping;
943 struct inode *inode = mapping->host;
944
945 if (vma->vm_flags & VM_MAYSHARE) {
946 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
947 region_add(&inode->i_mapping->private_list, idx, idx + 1);
948
949 } else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
950 pgoff_t idx = vma_hugecache_offset(h, vma, addr);
951 struct resv_map *reservations = vma_resv_map(vma);
952
953 /* Mark this page used in the map. */
954 region_add(&reservations->regions, idx, idx + 1);
955 }
956 }
957
958 static struct page *alloc_huge_page(struct vm_area_struct *vma,
959 unsigned long addr, int avoid_reserve)
960 {
961 struct hstate *h = hstate_vma(vma);
962 struct page *page;
963 struct address_space *mapping = vma->vm_file->f_mapping;
964 struct inode *inode = mapping->host;
965 long chg;
966
967 /*
968 * Processes that did not create the mapping will have no reserves and
969 * will not have accounted against quota. Check that the quota can be
970 * made before satisfying the allocation
971 * MAP_NORESERVE mappings may also need pages and quota allocated
972 * if no reserve mapping overlaps.
973 */
974 chg = vma_needs_reservation(h, vma, addr);
975 if (chg < 0)
976 return ERR_PTR(chg);
977 if (chg)
978 if (hugetlb_get_quota(inode->i_mapping, chg))
979 return ERR_PTR(-ENOSPC);
980
981 spin_lock(&hugetlb_lock);
982 page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
983 spin_unlock(&hugetlb_lock);
984
985 if (!page) {
986 page = alloc_buddy_huge_page(h, vma, addr);
987 if (!page) {
988 hugetlb_put_quota(inode->i_mapping, chg);
989 return ERR_PTR(-VM_FAULT_OOM);
990 }
991 }
992
993 set_page_refcounted(page);
994 set_page_private(page, (unsigned long) mapping);
995
996 vma_commit_reservation(h, vma, addr);
997
998 return page;
999 }
1000
1001 int __weak alloc_bootmem_huge_page(struct hstate *h)
1002 {
1003 struct huge_bootmem_page *m;
1004 int nr_nodes = nodes_weight(node_online_map);
1005
1006 while (nr_nodes) {
1007 void *addr;
1008
1009 addr = __alloc_bootmem_node_nopanic(
1010 NODE_DATA(h->hugetlb_next_nid),
1011 huge_page_size(h), huge_page_size(h), 0);
1012
1013 if (addr) {
1014 /*
1015 * Use the beginning of the huge page to store the
1016 * huge_bootmem_page struct (until gather_bootmem
1017 * puts them into the mem_map).
1018 */
1019 m = addr;
1020 goto found;
1021 }
1022 hstate_next_node(h);
1023 nr_nodes--;
1024 }
1025 return 0;
1026
1027 found:
1028 BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));
1029 /* Put them into a private list first because mem_map is not up yet */
1030 list_add(&m->list, &huge_boot_pages);
1031 m->hstate = h;
1032 return 1;
1033 }
1034
1035 static void prep_compound_huge_page(struct page *page, int order)
1036 {
1037 if (unlikely(order > (MAX_ORDER - 1)))
1038 prep_compound_gigantic_page(page, order);
1039 else
1040 prep_compound_page(page, order);
1041 }
1042
1043 /* Put bootmem huge pages into the standard lists after mem_map is up */
1044 static void __init gather_bootmem_prealloc(void)
1045 {
1046 struct huge_bootmem_page *m;
1047
1048 list_for_each_entry(m, &huge_boot_pages, list) {
1049 struct page *page = virt_to_page(m);
1050 struct hstate *h = m->hstate;
1051 __ClearPageReserved(page);
1052 WARN_ON(page_count(page) != 1);
1053 prep_compound_huge_page(page, h->order);
1054 prep_new_huge_page(h, page, page_to_nid(page));
1055 }
1056 }
1057
1058 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
1059 {
1060 unsigned long i;
1061
1062 for (i = 0; i < h->max_huge_pages; ++i) {
1063 if (h->order >= MAX_ORDER) {
1064 if (!alloc_bootmem_huge_page(h))
1065 break;
1066 } else if (!alloc_fresh_huge_page(h))
1067 break;
1068 }
1069 h->max_huge_pages = i;
1070 }
1071
1072 static void __init hugetlb_init_hstates(void)
1073 {
1074 struct hstate *h;
1075
1076 for_each_hstate(h) {
1077 /* oversize hugepages were init'ed in early boot */
1078 if (h->order < MAX_ORDER)
1079 hugetlb_hstate_alloc_pages(h);
1080 }
1081 }
1082
1083 static char * __init memfmt(char *buf, unsigned long n)
1084 {
1085 if (n >= (1UL << 30))
1086 sprintf(buf, "%lu GB", n >> 30);
1087 else if (n >= (1UL << 20))
1088 sprintf(buf, "%lu MB", n >> 20);
1089 else
1090 sprintf(buf, "%lu KB", n >> 10);
1091 return buf;
1092 }
1093
1094 static void __init report_hugepages(void)
1095 {
1096 struct hstate *h;
1097
1098 for_each_hstate(h) {
1099 char buf[32];
1100 printk(KERN_INFO "HugeTLB registered %s page size, "
1101 "pre-allocated %ld pages\n",
1102 memfmt(buf, huge_page_size(h)),
1103 h->free_huge_pages);
1104 }
1105 }
1106
1107 #ifdef CONFIG_HIGHMEM
1108 static void try_to_free_low(struct hstate *h, unsigned long count)
1109 {
1110 int i;
1111
1112 if (h->order >= MAX_ORDER)
1113 return;
1114
1115 for (i = 0; i < MAX_NUMNODES; ++i) {
1116 struct page *page, *next;
1117 struct list_head *freel = &h->hugepage_freelists[i];
1118 list_for_each_entry_safe(page, next, freel, lru) {
1119 if (count >= h->nr_huge_pages)
1120 return;
1121 if (PageHighMem(page))
1122 continue;
1123 list_del(&page->lru);
1124 update_and_free_page(h, page);
1125 h->free_huge_pages--;
1126 h->free_huge_pages_node[page_to_nid(page)]--;
1127 }
1128 }
1129 }
1130 #else
1131 static inline void try_to_free_low(struct hstate *h, unsigned long count)
1132 {
1133 }
1134 #endif
1135
1136 /*
1137 * Increment or decrement surplus_huge_pages. Keep node-specific counters
1138 * balanced by operating on them in a round-robin fashion.
1139 * Returns 1 if an adjustment was made.
1140 */
1141 static int adjust_pool_surplus(struct hstate *h, int delta)
1142 {
1143 static int prev_nid;
1144 int nid = prev_nid;
1145 int ret = 0;
1146
1147 VM_BUG_ON(delta != -1 && delta != 1);
1148 do {
1149 nid = next_node(nid, node_online_map);
1150 if (nid == MAX_NUMNODES)
1151 nid = first_node(node_online_map);
1152
1153 /* To shrink on this node, there must be a surplus page */
1154 if (delta < 0 && !h->surplus_huge_pages_node[nid])
1155 continue;
1156 /* Surplus cannot exceed the total number of pages */
1157 if (delta > 0 && h->surplus_huge_pages_node[nid] >=
1158 h->nr_huge_pages_node[nid])
1159 continue;
1160
1161 h->surplus_huge_pages += delta;
1162 h->surplus_huge_pages_node[nid] += delta;
1163 ret = 1;
1164 break;
1165 } while (nid != prev_nid);
1166
1167 prev_nid = nid;
1168 return ret;
1169 }
1170
1171 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1172 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count)
1173 {
1174 unsigned long min_count, ret;
1175
1176 if (h->order >= MAX_ORDER)
1177 return h->max_huge_pages;
1178
1179 /*
1180 * Increase the pool size
1181 * First take pages out of surplus state. Then make up the
1182 * remaining difference by allocating fresh huge pages.
1183 *
1184 * We might race with alloc_buddy_huge_page() here and be unable
1185 * to convert a surplus huge page to a normal huge page. That is
1186 * not critical, though, it just means the overall size of the
1187 * pool might be one hugepage larger than it needs to be, but
1188 * within all the constraints specified by the sysctls.
1189 */
1190 spin_lock(&hugetlb_lock);
1191 while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1192 if (!adjust_pool_surplus(h, -1))
1193 break;
1194 }
1195
1196 while (count > persistent_huge_pages(h)) {
1197 /*
1198 * If this allocation races such that we no longer need the
1199 * page, free_huge_page will handle it by freeing the page
1200 * and reducing the surplus.
1201 */
1202 spin_unlock(&hugetlb_lock);
1203 ret = alloc_fresh_huge_page(h);
1204 spin_lock(&hugetlb_lock);
1205 if (!ret)
1206 goto out;
1207
1208 }
1209
1210 /*
1211 * Decrease the pool size
1212 * First return free pages to the buddy allocator (being careful
1213 * to keep enough around to satisfy reservations). Then place
1214 * pages into surplus state as needed so the pool will shrink
1215 * to the desired size as pages become free.
1216 *
1217 * By placing pages into the surplus state independent of the
1218 * overcommit value, we are allowing the surplus pool size to
1219 * exceed overcommit. There are few sane options here. Since
1220 * alloc_buddy_huge_page() is checking the global counter,
1221 * though, we'll note that we're not allowed to exceed surplus
1222 * and won't grow the pool anywhere else. Not until one of the
1223 * sysctls are changed, or the surplus pages go out of use.
1224 */
1225 min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1226 min_count = max(count, min_count);
1227 try_to_free_low(h, min_count);
1228 while (min_count < persistent_huge_pages(h)) {
1229 struct page *page = dequeue_huge_page(h);
1230 if (!page)
1231 break;
1232 update_and_free_page(h, page);
1233 }
1234 while (count < persistent_huge_pages(h)) {
1235 if (!adjust_pool_surplus(h, 1))
1236 break;
1237 }
1238 out:
1239 ret = persistent_huge_pages(h);
1240 spin_unlock(&hugetlb_lock);
1241 return ret;
1242 }
1243
1244 #define HSTATE_ATTR_RO(_name) \
1245 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1246
1247 #define HSTATE_ATTR(_name) \
1248 static struct kobj_attribute _name##_attr = \
1249 __ATTR(_name, 0644, _name##_show, _name##_store)
1250
1251 static struct kobject *hugepages_kobj;
1252 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1253
1254 static struct hstate *kobj_to_hstate(struct kobject *kobj)
1255 {
1256 int i;
1257 for (i = 0; i < HUGE_MAX_HSTATE; i++)
1258 if (hstate_kobjs[i] == kobj)
1259 return &hstates[i];
1260 BUG();
1261 return NULL;
1262 }
1263
1264 static ssize_t nr_hugepages_show(struct kobject *kobj,
1265 struct kobj_attribute *attr, char *buf)
1266 {
1267 struct hstate *h = kobj_to_hstate(kobj);
1268 return sprintf(buf, "%lu\n", h->nr_huge_pages);
1269 }
1270 static ssize_t nr_hugepages_store(struct kobject *kobj,
1271 struct kobj_attribute *attr, const char *buf, size_t count)
1272 {
1273 int err;
1274 unsigned long input;
1275 struct hstate *h = kobj_to_hstate(kobj);
1276
1277 err = strict_strtoul(buf, 10, &input);
1278 if (err)
1279 return 0;
1280
1281 h->max_huge_pages = set_max_huge_pages(h, input);
1282
1283 return count;
1284 }
1285 HSTATE_ATTR(nr_hugepages);
1286
1287 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1288 struct kobj_attribute *attr, char *buf)
1289 {
1290 struct hstate *h = kobj_to_hstate(kobj);
1291 return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1292 }
1293 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1294 struct kobj_attribute *attr, const char *buf, size_t count)
1295 {
1296 int err;
1297 unsigned long input;
1298 struct hstate *h = kobj_to_hstate(kobj);
1299
1300 err = strict_strtoul(buf, 10, &input);
1301 if (err)
1302 return 0;
1303
1304 spin_lock(&hugetlb_lock);
1305 h->nr_overcommit_huge_pages = input;
1306 spin_unlock(&hugetlb_lock);
1307
1308 return count;
1309 }
1310 HSTATE_ATTR(nr_overcommit_hugepages);
1311
1312 static ssize_t free_hugepages_show(struct kobject *kobj,
1313 struct kobj_attribute *attr, char *buf)
1314 {
1315 struct hstate *h = kobj_to_hstate(kobj);
1316 return sprintf(buf, "%lu\n", h->free_huge_pages);
1317 }
1318 HSTATE_ATTR_RO(free_hugepages);
1319
1320 static ssize_t resv_hugepages_show(struct kobject *kobj,
1321 struct kobj_attribute *attr, char *buf)
1322 {
1323 struct hstate *h = kobj_to_hstate(kobj);
1324 return sprintf(buf, "%lu\n", h->resv_huge_pages);
1325 }
1326 HSTATE_ATTR_RO(resv_hugepages);
1327
1328 static ssize_t surplus_hugepages_show(struct kobject *kobj,
1329 struct kobj_attribute *attr, char *buf)
1330 {
1331 struct hstate *h = kobj_to_hstate(kobj);
1332 return sprintf(buf, "%lu\n", h->surplus_huge_pages);
1333 }
1334 HSTATE_ATTR_RO(surplus_hugepages);
1335
1336 static struct attribute *hstate_attrs[] = {
1337 &nr_hugepages_attr.attr,
1338 &nr_overcommit_hugepages_attr.attr,
1339 &free_hugepages_attr.attr,
1340 &resv_hugepages_attr.attr,
1341 &surplus_hugepages_attr.attr,
1342 NULL,
1343 };
1344
1345 static struct attribute_group hstate_attr_group = {
1346 .attrs = hstate_attrs,
1347 };
1348
1349 static int __init hugetlb_sysfs_add_hstate(struct hstate *h)
1350 {
1351 int retval;
1352
1353 hstate_kobjs[h - hstates] = kobject_create_and_add(h->name,
1354 hugepages_kobj);
1355 if (!hstate_kobjs[h - hstates])
1356 return -ENOMEM;
1357
1358 retval = sysfs_create_group(hstate_kobjs[h - hstates],
1359 &hstate_attr_group);
1360 if (retval)
1361 kobject_put(hstate_kobjs[h - hstates]);
1362
1363 return retval;
1364 }
1365
1366 static void __init hugetlb_sysfs_init(void)
1367 {
1368 struct hstate *h;
1369 int err;
1370
1371 hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1372 if (!hugepages_kobj)
1373 return;
1374
1375 for_each_hstate(h) {
1376 err = hugetlb_sysfs_add_hstate(h);
1377 if (err)
1378 printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
1379 h->name);
1380 }
1381 }
1382
1383 static void __exit hugetlb_exit(void)
1384 {
1385 struct hstate *h;
1386
1387 for_each_hstate(h) {
1388 kobject_put(hstate_kobjs[h - hstates]);
1389 }
1390
1391 kobject_put(hugepages_kobj);
1392 }
1393 module_exit(hugetlb_exit);
1394
1395 static int __init hugetlb_init(void)
1396 {
1397 /* Some platform decide whether they support huge pages at boot
1398 * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when
1399 * there is no such support
1400 */
1401 if (HPAGE_SHIFT == 0)
1402 return 0;
1403
1404 if (!size_to_hstate(default_hstate_size)) {
1405 default_hstate_size = HPAGE_SIZE;
1406 if (!size_to_hstate(default_hstate_size))
1407 hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
1408 }
1409 default_hstate_idx = size_to_hstate(default_hstate_size) - hstates;
1410 if (default_hstate_max_huge_pages)
1411 default_hstate.max_huge_pages = default_hstate_max_huge_pages;
1412
1413 hugetlb_init_hstates();
1414
1415 gather_bootmem_prealloc();
1416
1417 report_hugepages();
1418
1419 hugetlb_sysfs_init();
1420
1421 return 0;
1422 }
1423 module_init(hugetlb_init);
1424
1425 /* Should be called on processing a hugepagesz=... option */
1426 void __init hugetlb_add_hstate(unsigned order)
1427 {
1428 struct hstate *h;
1429 unsigned long i;
1430
1431 if (size_to_hstate(PAGE_SIZE << order)) {
1432 printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
1433 return;
1434 }
1435 BUG_ON(max_hstate >= HUGE_MAX_HSTATE);
1436 BUG_ON(order == 0);
1437 h = &hstates[max_hstate++];
1438 h->order = order;
1439 h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1440 h->nr_huge_pages = 0;
1441 h->free_huge_pages = 0;
1442 for (i = 0; i < MAX_NUMNODES; ++i)
1443 INIT_LIST_HEAD(&h->hugepage_freelists[i]);
1444 h->hugetlb_next_nid = first_node(node_online_map);
1445 snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
1446 huge_page_size(h)/1024);
1447
1448 parsed_hstate = h;
1449 }
1450
1451 static int __init hugetlb_nrpages_setup(char *s)
1452 {
1453 unsigned long *mhp;
1454 static unsigned long *last_mhp;
1455
1456 /*
1457 * !max_hstate means we haven't parsed a hugepagesz= parameter yet,
1458 * so this hugepages= parameter goes to the "default hstate".
1459 */
1460 if (!max_hstate)
1461 mhp = &default_hstate_max_huge_pages;
1462 else
1463 mhp = &parsed_hstate->max_huge_pages;
1464
1465 if (mhp == last_mhp) {
1466 printk(KERN_WARNING "hugepages= specified twice without "
1467 "interleaving hugepagesz=, ignoring\n");
1468 return 1;
1469 }
1470
1471 if (sscanf(s, "%lu", mhp) <= 0)
1472 *mhp = 0;
1473
1474 /*
1475 * Global state is always initialized later in hugetlb_init.
1476 * But we need to allocate >= MAX_ORDER hstates here early to still
1477 * use the bootmem allocator.
1478 */
1479 if (max_hstate && parsed_hstate->order >= MAX_ORDER)
1480 hugetlb_hstate_alloc_pages(parsed_hstate);
1481
1482 last_mhp = mhp;
1483
1484 return 1;
1485 }
1486 __setup("hugepages=", hugetlb_nrpages_setup);
1487
1488 static int __init hugetlb_default_setup(char *s)
1489 {
1490 default_hstate_size = memparse(s, &s);
1491 return 1;
1492 }
1493 __setup("default_hugepagesz=", hugetlb_default_setup);
1494
1495 static unsigned int cpuset_mems_nr(unsigned int *array)
1496 {
1497 int node;
1498 unsigned int nr = 0;
1499
1500 for_each_node_mask(node, cpuset_current_mems_allowed)
1501 nr += array[node];
1502
1503 return nr;
1504 }
1505
1506 #ifdef CONFIG_SYSCTL
1507 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
1508 struct file *file, void __user *buffer,
1509 size_t *length, loff_t *ppos)
1510 {
1511 struct hstate *h = &default_hstate;
1512 unsigned long tmp;
1513
1514 if (!write)
1515 tmp = h->max_huge_pages;
1516
1517 table->data = &tmp;
1518 table->maxlen = sizeof(unsigned long);
1519 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
1520
1521 if (write)
1522 h->max_huge_pages = set_max_huge_pages(h, tmp);
1523
1524 return 0;
1525 }
1526
1527 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
1528 struct file *file, void __user *buffer,
1529 size_t *length, loff_t *ppos)
1530 {
1531 proc_dointvec(table, write, file, buffer, length, ppos);
1532 if (hugepages_treat_as_movable)
1533 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
1534 else
1535 htlb_alloc_mask = GFP_HIGHUSER;
1536 return 0;
1537 }
1538
1539 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
1540 struct file *file, void __user *buffer,
1541 size_t *length, loff_t *ppos)
1542 {
1543 struct hstate *h = &default_hstate;
1544 unsigned long tmp;
1545
1546 if (!write)
1547 tmp = h->nr_overcommit_huge_pages;
1548
1549 table->data = &tmp;
1550 table->maxlen = sizeof(unsigned long);
1551 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
1552
1553 if (write) {
1554 spin_lock(&hugetlb_lock);
1555 h->nr_overcommit_huge_pages = tmp;
1556 spin_unlock(&hugetlb_lock);
1557 }
1558
1559 return 0;
1560 }
1561
1562 #endif /* CONFIG_SYSCTL */
1563
1564 void hugetlb_report_meminfo(struct seq_file *m)
1565 {
1566 struct hstate *h = &default_hstate;
1567 seq_printf(m,
1568 "HugePages_Total: %5lu\n"
1569 "HugePages_Free: %5lu\n"
1570 "HugePages_Rsvd: %5lu\n"
1571 "HugePages_Surp: %5lu\n"
1572 "Hugepagesize: %8lu kB\n",
1573 h->nr_huge_pages,
1574 h->free_huge_pages,
1575 h->resv_huge_pages,
1576 h->surplus_huge_pages,
1577 1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
1578 }
1579
1580 int hugetlb_report_node_meminfo(int nid, char *buf)
1581 {
1582 struct hstate *h = &default_hstate;
1583 return sprintf(buf,
1584 "Node %d HugePages_Total: %5u\n"
1585 "Node %d HugePages_Free: %5u\n"
1586 "Node %d HugePages_Surp: %5u\n",
1587 nid, h->nr_huge_pages_node[nid],
1588 nid, h->free_huge_pages_node[nid],
1589 nid, h->surplus_huge_pages_node[nid]);
1590 }
1591
1592 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
1593 unsigned long hugetlb_total_pages(void)
1594 {
1595 struct hstate *h = &default_hstate;
1596 return h->nr_huge_pages * pages_per_huge_page(h);
1597 }
1598
1599 static int hugetlb_acct_memory(struct hstate *h, long delta)
1600 {
1601 int ret = -ENOMEM;
1602
1603 spin_lock(&hugetlb_lock);
1604 /*
1605 * When cpuset is configured, it breaks the strict hugetlb page
1606 * reservation as the accounting is done on a global variable. Such
1607 * reservation is completely rubbish in the presence of cpuset because
1608 * the reservation is not checked against page availability for the
1609 * current cpuset. Application can still potentially OOM'ed by kernel
1610 * with lack of free htlb page in cpuset that the task is in.
1611 * Attempt to enforce strict accounting with cpuset is almost
1612 * impossible (or too ugly) because cpuset is too fluid that
1613 * task or memory node can be dynamically moved between cpusets.
1614 *
1615 * The change of semantics for shared hugetlb mapping with cpuset is
1616 * undesirable. However, in order to preserve some of the semantics,
1617 * we fall back to check against current free page availability as
1618 * a best attempt and hopefully to minimize the impact of changing
1619 * semantics that cpuset has.
1620 */
1621 if (delta > 0) {
1622 if (gather_surplus_pages(h, delta) < 0)
1623 goto out;
1624
1625 if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
1626 return_unused_surplus_pages(h, delta);
1627 goto out;
1628 }
1629 }
1630
1631 ret = 0;
1632 if (delta < 0)
1633 return_unused_surplus_pages(h, (unsigned long) -delta);
1634
1635 out:
1636 spin_unlock(&hugetlb_lock);
1637 return ret;
1638 }
1639
1640 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
1641 {
1642 struct resv_map *reservations = vma_resv_map(vma);
1643
1644 /*
1645 * This new VMA should share its siblings reservation map if present.
1646 * The VMA will only ever have a valid reservation map pointer where
1647 * it is being copied for another still existing VMA. As that VMA
1648 * has a reference to the reservation map it cannot dissappear until
1649 * after this open call completes. It is therefore safe to take a
1650 * new reference here without additional locking.
1651 */
1652 if (reservations)
1653 kref_get(&reservations->refs);
1654 }
1655
1656 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
1657 {
1658 struct hstate *h = hstate_vma(vma);
1659 struct resv_map *reservations = vma_resv_map(vma);
1660 unsigned long reserve;
1661 unsigned long start;
1662 unsigned long end;
1663
1664 if (reservations) {
1665 start = vma_hugecache_offset(h, vma, vma->vm_start);
1666 end = vma_hugecache_offset(h, vma, vma->vm_end);
1667
1668 reserve = (end - start) -
1669 region_count(&reservations->regions, start, end);
1670
1671 kref_put(&reservations->refs, resv_map_release);
1672
1673 if (reserve) {
1674 hugetlb_acct_memory(h, -reserve);
1675 hugetlb_put_quota(vma->vm_file->f_mapping, reserve);
1676 }
1677 }
1678 }
1679
1680 /*
1681 * We cannot handle pagefaults against hugetlb pages at all. They cause
1682 * handle_mm_fault() to try to instantiate regular-sized pages in the
1683 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
1684 * this far.
1685 */
1686 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1687 {
1688 BUG();
1689 return 0;
1690 }
1691
1692 struct vm_operations_struct hugetlb_vm_ops = {
1693 .fault = hugetlb_vm_op_fault,
1694 .open = hugetlb_vm_op_open,
1695 .close = hugetlb_vm_op_close,
1696 };
1697
1698 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
1699 int writable)
1700 {
1701 pte_t entry;
1702
1703 if (writable) {
1704 entry =
1705 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
1706 } else {
1707 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
1708 }
1709 entry = pte_mkyoung(entry);
1710 entry = pte_mkhuge(entry);
1711
1712 return entry;
1713 }
1714
1715 static void set_huge_ptep_writable(struct vm_area_struct *vma,
1716 unsigned long address, pte_t *ptep)
1717 {
1718 pte_t entry;
1719
1720 entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
1721 if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
1722 update_mmu_cache(vma, address, entry);
1723 }
1724 }
1725
1726
1727 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
1728 struct vm_area_struct *vma)
1729 {
1730 pte_t *src_pte, *dst_pte, entry;
1731 struct page *ptepage;
1732 unsigned long addr;
1733 int cow;
1734 struct hstate *h = hstate_vma(vma);
1735 unsigned long sz = huge_page_size(h);
1736
1737 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
1738
1739 for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
1740 src_pte = huge_pte_offset(src, addr);
1741 if (!src_pte)
1742 continue;
1743 dst_pte = huge_pte_alloc(dst, addr, sz);
1744 if (!dst_pte)
1745 goto nomem;
1746
1747 /* If the pagetables are shared don't copy or take references */
1748 if (dst_pte == src_pte)
1749 continue;
1750
1751 spin_lock(&dst->page_table_lock);
1752 spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
1753 if (!huge_pte_none(huge_ptep_get(src_pte))) {
1754 if (cow)
1755 huge_ptep_set_wrprotect(src, addr, src_pte);
1756 entry = huge_ptep_get(src_pte);
1757 ptepage = pte_page(entry);
1758 get_page(ptepage);
1759 set_huge_pte_at(dst, addr, dst_pte, entry);
1760 }
1761 spin_unlock(&src->page_table_lock);
1762 spin_unlock(&dst->page_table_lock);
1763 }
1764 return 0;
1765
1766 nomem:
1767 return -ENOMEM;
1768 }
1769
1770 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
1771 unsigned long end, struct page *ref_page)
1772 {
1773 struct mm_struct *mm = vma->vm_mm;
1774 unsigned long address;
1775 pte_t *ptep;
1776 pte_t pte;
1777 struct page *page;
1778 struct page *tmp;
1779 struct hstate *h = hstate_vma(vma);
1780 unsigned long sz = huge_page_size(h);
1781
1782 /*
1783 * A page gathering list, protected by per file i_mmap_lock. The
1784 * lock is used to avoid list corruption from multiple unmapping
1785 * of the same page since we are using page->lru.
1786 */
1787 LIST_HEAD(page_list);
1788
1789 WARN_ON(!is_vm_hugetlb_page(vma));
1790 BUG_ON(start & ~huge_page_mask(h));
1791 BUG_ON(end & ~huge_page_mask(h));
1792
1793 mmu_notifier_invalidate_range_start(mm, start, end);
1794 spin_lock(&mm->page_table_lock);
1795 for (address = start; address < end; address += sz) {
1796 ptep = huge_pte_offset(mm, address);
1797 if (!ptep)
1798 continue;
1799
1800 if (huge_pmd_unshare(mm, &address, ptep))
1801 continue;
1802
1803 /*
1804 * If a reference page is supplied, it is because a specific
1805 * page is being unmapped, not a range. Ensure the page we
1806 * are about to unmap is the actual page of interest.
1807 */
1808 if (ref_page) {
1809 pte = huge_ptep_get(ptep);
1810 if (huge_pte_none(pte))
1811 continue;
1812 page = pte_page(pte);
1813 if (page != ref_page)
1814 continue;
1815
1816 /*
1817 * Mark the VMA as having unmapped its page so that
1818 * future faults in this VMA will fail rather than
1819 * looking like data was lost
1820 */
1821 set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
1822 }
1823
1824 pte = huge_ptep_get_and_clear(mm, address, ptep);
1825 if (huge_pte_none(pte))
1826 continue;
1827
1828 page = pte_page(pte);
1829 if (pte_dirty(pte))
1830 set_page_dirty(page);
1831 list_add(&page->lru, &page_list);
1832 }
1833 spin_unlock(&mm->page_table_lock);
1834 flush_tlb_range(vma, start, end);
1835 mmu_notifier_invalidate_range_end(mm, start, end);
1836 list_for_each_entry_safe(page, tmp, &page_list, lru) {
1837 list_del(&page->lru);
1838 put_page(page);
1839 }
1840 }
1841
1842 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
1843 unsigned long end, struct page *ref_page)
1844 {
1845 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1846 __unmap_hugepage_range(vma, start, end, ref_page);
1847 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1848 }
1849
1850 /*
1851 * This is called when the original mapper is failing to COW a MAP_PRIVATE
1852 * mappping it owns the reserve page for. The intention is to unmap the page
1853 * from other VMAs and let the children be SIGKILLed if they are faulting the
1854 * same region.
1855 */
1856 static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
1857 struct page *page, unsigned long address)
1858 {
1859 struct hstate *h = hstate_vma(vma);
1860 struct vm_area_struct *iter_vma;
1861 struct address_space *mapping;
1862 struct prio_tree_iter iter;
1863 pgoff_t pgoff;
1864
1865 /*
1866 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
1867 * from page cache lookup which is in HPAGE_SIZE units.
1868 */
1869 address = address & huge_page_mask(h);
1870 pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
1871 + (vma->vm_pgoff >> PAGE_SHIFT);
1872 mapping = (struct address_space *)page_private(page);
1873
1874 vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
1875 /* Do not unmap the current VMA */
1876 if (iter_vma == vma)
1877 continue;
1878
1879 /*
1880 * Unmap the page from other VMAs without their own reserves.
1881 * They get marked to be SIGKILLed if they fault in these
1882 * areas. This is because a future no-page fault on this VMA
1883 * could insert a zeroed page instead of the data existing
1884 * from the time of fork. This would look like data corruption
1885 */
1886 if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
1887 unmap_hugepage_range(iter_vma,
1888 address, address + huge_page_size(h),
1889 page);
1890 }
1891
1892 return 1;
1893 }
1894
1895 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
1896 unsigned long address, pte_t *ptep, pte_t pte,
1897 struct page *pagecache_page)
1898 {
1899 struct hstate *h = hstate_vma(vma);
1900 struct page *old_page, *new_page;
1901 int avoidcopy;
1902 int outside_reserve = 0;
1903
1904 old_page = pte_page(pte);
1905
1906 retry_avoidcopy:
1907 /* If no-one else is actually using this page, avoid the copy
1908 * and just make the page writable */
1909 avoidcopy = (page_count(old_page) == 1);
1910 if (avoidcopy) {
1911 set_huge_ptep_writable(vma, address, ptep);
1912 return 0;
1913 }
1914
1915 /*
1916 * If the process that created a MAP_PRIVATE mapping is about to
1917 * perform a COW due to a shared page count, attempt to satisfy
1918 * the allocation without using the existing reserves. The pagecache
1919 * page is used to determine if the reserve at this address was
1920 * consumed or not. If reserves were used, a partial faulted mapping
1921 * at the time of fork() could consume its reserves on COW instead
1922 * of the full address range.
1923 */
1924 if (!(vma->vm_flags & VM_MAYSHARE) &&
1925 is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
1926 old_page != pagecache_page)
1927 outside_reserve = 1;
1928
1929 page_cache_get(old_page);
1930 new_page = alloc_huge_page(vma, address, outside_reserve);
1931
1932 if (IS_ERR(new_page)) {
1933 page_cache_release(old_page);
1934
1935 /*
1936 * If a process owning a MAP_PRIVATE mapping fails to COW,
1937 * it is due to references held by a child and an insufficient
1938 * huge page pool. To guarantee the original mappers
1939 * reliability, unmap the page from child processes. The child
1940 * may get SIGKILLed if it later faults.
1941 */
1942 if (outside_reserve) {
1943 BUG_ON(huge_pte_none(pte));
1944 if (unmap_ref_private(mm, vma, old_page, address)) {
1945 BUG_ON(page_count(old_page) != 1);
1946 BUG_ON(huge_pte_none(pte));
1947 goto retry_avoidcopy;
1948 }
1949 WARN_ON_ONCE(1);
1950 }
1951
1952 return -PTR_ERR(new_page);
1953 }
1954
1955 spin_unlock(&mm->page_table_lock);
1956 copy_huge_page(new_page, old_page, address, vma);
1957 __SetPageUptodate(new_page);
1958 spin_lock(&mm->page_table_lock);
1959
1960 ptep = huge_pte_offset(mm, address & huge_page_mask(h));
1961 if (likely(pte_same(huge_ptep_get(ptep), pte))) {
1962 /* Break COW */
1963 huge_ptep_clear_flush(vma, address, ptep);
1964 set_huge_pte_at(mm, address, ptep,
1965 make_huge_pte(vma, new_page, 1));
1966 /* Make the old page be freed below */
1967 new_page = old_page;
1968 }
1969 page_cache_release(new_page);
1970 page_cache_release(old_page);
1971 return 0;
1972 }
1973
1974 /* Return the pagecache page at a given address within a VMA */
1975 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
1976 struct vm_area_struct *vma, unsigned long address)
1977 {
1978 struct address_space *mapping;
1979 pgoff_t idx;
1980
1981 mapping = vma->vm_file->f_mapping;
1982 idx = vma_hugecache_offset(h, vma, address);
1983
1984 return find_lock_page(mapping, idx);
1985 }
1986
1987 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
1988 unsigned long address, pte_t *ptep, unsigned int flags)
1989 {
1990 struct hstate *h = hstate_vma(vma);
1991 int ret = VM_FAULT_SIGBUS;
1992 pgoff_t idx;
1993 unsigned long size;
1994 struct page *page;
1995 struct address_space *mapping;
1996 pte_t new_pte;
1997
1998 /*
1999 * Currently, we are forced to kill the process in the event the
2000 * original mapper has unmapped pages from the child due to a failed
2001 * COW. Warn that such a situation has occured as it may not be obvious
2002 */
2003 if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
2004 printk(KERN_WARNING
2005 "PID %d killed due to inadequate hugepage pool\n",
2006 current->pid);
2007 return ret;
2008 }
2009
2010 mapping = vma->vm_file->f_mapping;
2011 idx = vma_hugecache_offset(h, vma, address);
2012
2013 /*
2014 * Use page lock to guard against racing truncation
2015 * before we get page_table_lock.
2016 */
2017 retry:
2018 page = find_lock_page(mapping, idx);
2019 if (!page) {
2020 size = i_size_read(mapping->host) >> huge_page_shift(h);
2021 if (idx >= size)
2022 goto out;
2023 page = alloc_huge_page(vma, address, 0);
2024 if (IS_ERR(page)) {
2025 ret = -PTR_ERR(page);
2026 goto out;
2027 }
2028 clear_huge_page(page, address, huge_page_size(h));
2029 __SetPageUptodate(page);
2030
2031 if (vma->vm_flags & VM_MAYSHARE) {
2032 int err;
2033 struct inode *inode = mapping->host;
2034
2035 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
2036 if (err) {
2037 put_page(page);
2038 if (err == -EEXIST)
2039 goto retry;
2040 goto out;
2041 }
2042
2043 spin_lock(&inode->i_lock);
2044 inode->i_blocks += blocks_per_huge_page(h);
2045 spin_unlock(&inode->i_lock);
2046 } else
2047 lock_page(page);
2048 }
2049
2050 /*
2051 * If we are going to COW a private mapping later, we examine the
2052 * pending reservations for this page now. This will ensure that
2053 * any allocations necessary to record that reservation occur outside
2054 * the spinlock.
2055 */
2056 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
2057 if (vma_needs_reservation(h, vma, address) < 0) {
2058 ret = VM_FAULT_OOM;
2059 goto backout_unlocked;
2060 }
2061
2062 spin_lock(&mm->page_table_lock);
2063 size = i_size_read(mapping->host) >> huge_page_shift(h);
2064 if (idx >= size)
2065 goto backout;
2066
2067 ret = 0;
2068 if (!huge_pte_none(huge_ptep_get(ptep)))
2069 goto backout;
2070
2071 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
2072 && (vma->vm_flags & VM_SHARED)));
2073 set_huge_pte_at(mm, address, ptep, new_pte);
2074
2075 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
2076 /* Optimization, do the COW without a second fault */
2077 ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
2078 }
2079
2080 spin_unlock(&mm->page_table_lock);
2081 unlock_page(page);
2082 out:
2083 return ret;
2084
2085 backout:
2086 spin_unlock(&mm->page_table_lock);
2087 backout_unlocked:
2088 unlock_page(page);
2089 put_page(page);
2090 goto out;
2091 }
2092
2093 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2094 unsigned long address, unsigned int flags)
2095 {
2096 pte_t *ptep;
2097 pte_t entry;
2098 int ret;
2099 struct page *pagecache_page = NULL;
2100 static DEFINE_MUTEX(hugetlb_instantiation_mutex);
2101 struct hstate *h = hstate_vma(vma);
2102
2103 ptep = huge_pte_alloc(mm, address, huge_page_size(h));
2104 if (!ptep)
2105 return VM_FAULT_OOM;
2106
2107 /*
2108 * Serialize hugepage allocation and instantiation, so that we don't
2109 * get spurious allocation failures if two CPUs race to instantiate
2110 * the same page in the page cache.
2111 */
2112 mutex_lock(&hugetlb_instantiation_mutex);
2113 entry = huge_ptep_get(ptep);
2114 if (huge_pte_none(entry)) {
2115 ret = hugetlb_no_page(mm, vma, address, ptep, flags);
2116 goto out_mutex;
2117 }
2118
2119 ret = 0;
2120
2121 /*
2122 * If we are going to COW the mapping later, we examine the pending
2123 * reservations for this page now. This will ensure that any
2124 * allocations necessary to record that reservation occur outside the
2125 * spinlock. For private mappings, we also lookup the pagecache
2126 * page now as it is used to determine if a reservation has been
2127 * consumed.
2128 */
2129 if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) {
2130 if (vma_needs_reservation(h, vma, address) < 0) {
2131 ret = VM_FAULT_OOM;
2132 goto out_mutex;
2133 }
2134
2135 if (!(vma->vm_flags & VM_MAYSHARE))
2136 pagecache_page = hugetlbfs_pagecache_page(h,
2137 vma, address);
2138 }
2139
2140 spin_lock(&mm->page_table_lock);
2141 /* Check for a racing update before calling hugetlb_cow */
2142 if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
2143 goto out_page_table_lock;
2144
2145
2146 if (flags & FAULT_FLAG_WRITE) {
2147 if (!pte_write(entry)) {
2148 ret = hugetlb_cow(mm, vma, address, ptep, entry,
2149 pagecache_page);
2150 goto out_page_table_lock;
2151 }
2152 entry = pte_mkdirty(entry);
2153 }
2154 entry = pte_mkyoung(entry);
2155 if (huge_ptep_set_access_flags(vma, address, ptep, entry,
2156 flags & FAULT_FLAG_WRITE))
2157 update_mmu_cache(vma, address, entry);
2158
2159 out_page_table_lock:
2160 spin_unlock(&mm->page_table_lock);
2161
2162 if (pagecache_page) {
2163 unlock_page(pagecache_page);
2164 put_page(pagecache_page);
2165 }
2166
2167 out_mutex:
2168 mutex_unlock(&hugetlb_instantiation_mutex);
2169
2170 return ret;
2171 }
2172
2173 /* Can be overriden by architectures */
2174 __attribute__((weak)) struct page *
2175 follow_huge_pud(struct mm_struct *mm, unsigned long address,
2176 pud_t *pud, int write)
2177 {
2178 BUG();
2179 return NULL;
2180 }
2181
2182 static int huge_zeropage_ok(pte_t *ptep, int write, int shared)
2183 {
2184 if (!ptep || write || shared)
2185 return 0;
2186 else
2187 return huge_pte_none(huge_ptep_get(ptep));
2188 }
2189
2190 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
2191 struct page **pages, struct vm_area_struct **vmas,
2192 unsigned long *position, int *length, int i,
2193 int write)
2194 {
2195 unsigned long pfn_offset;
2196 unsigned long vaddr = *position;
2197 int remainder = *length;
2198 struct hstate *h = hstate_vma(vma);
2199 int zeropage_ok = 0;
2200 int shared = vma->vm_flags & VM_SHARED;
2201
2202 spin_lock(&mm->page_table_lock);
2203 while (vaddr < vma->vm_end && remainder) {
2204 pte_t *pte;
2205 struct page *page;
2206
2207 /*
2208 * Some archs (sparc64, sh*) have multiple pte_ts to
2209 * each hugepage. We have to make * sure we get the
2210 * first, for the page indexing below to work.
2211 */
2212 pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
2213 if (huge_zeropage_ok(pte, write, shared))
2214 zeropage_ok = 1;
2215
2216 if (!pte ||
2217 (huge_pte_none(huge_ptep_get(pte)) && !zeropage_ok) ||
2218 (write && !pte_write(huge_ptep_get(pte)))) {
2219 int ret;
2220
2221 spin_unlock(&mm->page_table_lock);
2222 ret = hugetlb_fault(mm, vma, vaddr, write);
2223 spin_lock(&mm->page_table_lock);
2224 if (!(ret & VM_FAULT_ERROR))
2225 continue;
2226
2227 remainder = 0;
2228 if (!i)
2229 i = -EFAULT;
2230 break;
2231 }
2232
2233 pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2234 page = pte_page(huge_ptep_get(pte));
2235 same_page:
2236 if (pages) {
2237 if (zeropage_ok)
2238 pages[i] = ZERO_PAGE(0);
2239 else
2240 pages[i] = mem_map_offset(page, pfn_offset);
2241 get_page(pages[i]);
2242 }
2243
2244 if (vmas)
2245 vmas[i] = vma;
2246
2247 vaddr += PAGE_SIZE;
2248 ++pfn_offset;
2249 --remainder;
2250 ++i;
2251 if (vaddr < vma->vm_end && remainder &&
2252 pfn_offset < pages_per_huge_page(h)) {
2253 /*
2254 * We use pfn_offset to avoid touching the pageframes
2255 * of this compound page.
2256 */
2257 goto same_page;
2258 }
2259 }
2260 spin_unlock(&mm->page_table_lock);
2261 *length = remainder;
2262 *position = vaddr;
2263
2264 return i;
2265 }
2266
2267 void hugetlb_change_protection(struct vm_area_struct *vma,
2268 unsigned long address, unsigned long end, pgprot_t newprot)
2269 {
2270 struct mm_struct *mm = vma->vm_mm;
2271 unsigned long start = address;
2272 pte_t *ptep;
2273 pte_t pte;
2274 struct hstate *h = hstate_vma(vma);
2275
2276 BUG_ON(address >= end);
2277 flush_cache_range(vma, address, end);
2278
2279 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2280 spin_lock(&mm->page_table_lock);
2281 for (; address < end; address += huge_page_size(h)) {
2282 ptep = huge_pte_offset(mm, address);
2283 if (!ptep)
2284 continue;
2285 if (huge_pmd_unshare(mm, &address, ptep))
2286 continue;
2287 if (!huge_pte_none(huge_ptep_get(ptep))) {
2288 pte = huge_ptep_get_and_clear(mm, address, ptep);
2289 pte = pte_mkhuge(pte_modify(pte, newprot));
2290 set_huge_pte_at(mm, address, ptep, pte);
2291 }
2292 }
2293 spin_unlock(&mm->page_table_lock);
2294 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2295
2296 flush_tlb_range(vma, start, end);
2297 }
2298
2299 int hugetlb_reserve_pages(struct inode *inode,
2300 long from, long to,
2301 struct vm_area_struct *vma,
2302 int acctflag)
2303 {
2304 long ret, chg;
2305 struct hstate *h = hstate_inode(inode);
2306
2307 /*
2308 * Only apply hugepage reservation if asked. At fault time, an
2309 * attempt will be made for VM_NORESERVE to allocate a page
2310 * and filesystem quota without using reserves
2311 */
2312 if (acctflag & VM_NORESERVE)
2313 return 0;
2314
2315 /*
2316 * Shared mappings base their reservation on the number of pages that
2317 * are already allocated on behalf of the file. Private mappings need
2318 * to reserve the full area even if read-only as mprotect() may be
2319 * called to make the mapping read-write. Assume !vma is a shm mapping
2320 */
2321 if (!vma || vma->vm_flags & VM_MAYSHARE)
2322 chg = region_chg(&inode->i_mapping->private_list, from, to);
2323 else {
2324 struct resv_map *resv_map = resv_map_alloc();
2325 if (!resv_map)
2326 return -ENOMEM;
2327
2328 chg = to - from;
2329
2330 set_vma_resv_map(vma, resv_map);
2331 set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
2332 }
2333
2334 if (chg < 0)
2335 return chg;
2336
2337 /* There must be enough filesystem quota for the mapping */
2338 if (hugetlb_get_quota(inode->i_mapping, chg))
2339 return -ENOSPC;
2340
2341 /*
2342 * Check enough hugepages are available for the reservation.
2343 * Hand back the quota if there are not
2344 */
2345 ret = hugetlb_acct_memory(h, chg);
2346 if (ret < 0) {
2347 hugetlb_put_quota(inode->i_mapping, chg);
2348 return ret;
2349 }
2350
2351 /*
2352 * Account for the reservations made. Shared mappings record regions
2353 * that have reservations as they are shared by multiple VMAs.
2354 * When the last VMA disappears, the region map says how much
2355 * the reservation was and the page cache tells how much of
2356 * the reservation was consumed. Private mappings are per-VMA and
2357 * only the consumed reservations are tracked. When the VMA
2358 * disappears, the original reservation is the VMA size and the
2359 * consumed reservations are stored in the map. Hence, nothing
2360 * else has to be done for private mappings here
2361 */
2362 if (!vma || vma->vm_flags & VM_MAYSHARE)
2363 region_add(&inode->i_mapping->private_list, from, to);
2364 return 0;
2365 }
2366
2367 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
2368 {
2369 struct hstate *h = hstate_inode(inode);
2370 long chg = region_truncate(&inode->i_mapping->private_list, offset);
2371
2372 spin_lock(&inode->i_lock);
2373 inode->i_blocks -= blocks_per_huge_page(h);
2374 spin_unlock(&inode->i_lock);
2375
2376 hugetlb_put_quota(inode->i_mapping, (chg - freed));
2377 hugetlb_acct_memory(h, -(chg - freed));
2378 }