xref: /openbmc/linux/mm/hugetlb.c (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
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 <linux/node.h>
28 #include "internal.h"
29 
30 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
31 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
32 unsigned long hugepages_treat_as_movable;
33 
34 static int max_hstate;
35 unsigned int default_hstate_idx;
36 struct hstate hstates[HUGE_MAX_HSTATE];
37 
38 __initdata LIST_HEAD(huge_boot_pages);
39 
40 /* for command line parsing */
41 static struct hstate * __initdata parsed_hstate;
42 static unsigned long __initdata default_hstate_max_huge_pages;
43 static unsigned long __initdata default_hstate_size;
44 
45 #define for_each_hstate(h) \
46 	for ((h) = hstates; (h) < &hstates[max_hstate]; (h)++)
47 
48 /*
49  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
50  */
51 static DEFINE_SPINLOCK(hugetlb_lock);
52 
53 /*
54  * Region tracking -- allows tracking of reservations and instantiated pages
55  *                    across the pages in a mapping.
56  *
57  * The region data structures are protected by a combination of the mmap_sem
58  * and the hugetlb_instantion_mutex.  To access or modify a region the caller
59  * must either hold the mmap_sem for write, or the mmap_sem for read and
60  * the hugetlb_instantiation mutex:
61  *
62  * 	down_write(&mm->mmap_sem);
63  * or
64  * 	down_read(&mm->mmap_sem);
65  * 	mutex_lock(&hugetlb_instantiation_mutex);
66  */
67 struct file_region {
68 	struct list_head link;
69 	long from;
70 	long to;
71 };
72 
73 static long region_add(struct list_head *head, long f, long t)
74 {
75 	struct file_region *rg, *nrg, *trg;
76 
77 	/* Locate the region we are either in or before. */
78 	list_for_each_entry(rg, head, link)
79 		if (f <= rg->to)
80 			break;
81 
82 	/* Round our left edge to the current segment if it encloses us. */
83 	if (f > rg->from)
84 		f = rg->from;
85 
86 	/* Check for and consume any regions we now overlap with. */
87 	nrg = rg;
88 	list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
89 		if (&rg->link == head)
90 			break;
91 		if (rg->from > t)
92 			break;
93 
94 		/* If this area reaches higher then extend our area to
95 		 * include it completely.  If this is not the first area
96 		 * which we intend to reuse, free it. */
97 		if (rg->to > t)
98 			t = rg->to;
99 		if (rg != nrg) {
100 			list_del(&rg->link);
101 			kfree(rg);
102 		}
103 	}
104 	nrg->from = f;
105 	nrg->to = t;
106 	return 0;
107 }
108 
109 static long region_chg(struct list_head *head, long f, long t)
110 {
111 	struct file_region *rg, *nrg;
112 	long chg = 0;
113 
114 	/* Locate the region we are before or in. */
115 	list_for_each_entry(rg, head, link)
116 		if (f <= rg->to)
117 			break;
118 
119 	/* If we are below the current region then a new region is required.
120 	 * Subtle, allocate a new region at the position but make it zero
121 	 * size such that we can guarantee to record the reservation. */
122 	if (&rg->link == head || t < rg->from) {
123 		nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
124 		if (!nrg)
125 			return -ENOMEM;
126 		nrg->from = f;
127 		nrg->to   = f;
128 		INIT_LIST_HEAD(&nrg->link);
129 		list_add(&nrg->link, rg->link.prev);
130 
131 		return t - f;
132 	}
133 
134 	/* Round our left edge to the current segment if it encloses us. */
135 	if (f > rg->from)
136 		f = rg->from;
137 	chg = t - f;
138 
139 	/* Check for and consume any regions we now overlap with. */
140 	list_for_each_entry(rg, rg->link.prev, link) {
141 		if (&rg->link == head)
142 			break;
143 		if (rg->from > t)
144 			return chg;
145 
146 		/* We overlap with this area, if it extends futher than
147 		 * us then we must extend ourselves.  Account for its
148 		 * existing reservation. */
149 		if (rg->to > t) {
150 			chg += rg->to - t;
151 			t = rg->to;
152 		}
153 		chg -= rg->to - rg->from;
154 	}
155 	return chg;
156 }
157 
158 static long region_truncate(struct list_head *head, long end)
159 {
160 	struct file_region *rg, *trg;
161 	long chg = 0;
162 
163 	/* Locate the region we are either in or before. */
164 	list_for_each_entry(rg, head, link)
165 		if (end <= rg->to)
166 			break;
167 	if (&rg->link == head)
168 		return 0;
169 
170 	/* If we are in the middle of a region then adjust it. */
171 	if (end > rg->from) {
172 		chg = rg->to - end;
173 		rg->to = end;
174 		rg = list_entry(rg->link.next, typeof(*rg), link);
175 	}
176 
177 	/* Drop any remaining regions. */
178 	list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
179 		if (&rg->link == head)
180 			break;
181 		chg += rg->to - rg->from;
182 		list_del(&rg->link);
183 		kfree(rg);
184 	}
185 	return chg;
186 }
187 
188 static long region_count(struct list_head *head, long f, long t)
189 {
190 	struct file_region *rg;
191 	long chg = 0;
192 
193 	/* Locate each segment we overlap with, and count that overlap. */
194 	list_for_each_entry(rg, head, link) {
195 		int seg_from;
196 		int seg_to;
197 
198 		if (rg->to <= f)
199 			continue;
200 		if (rg->from >= t)
201 			break;
202 
203 		seg_from = max(rg->from, f);
204 		seg_to = min(rg->to, t);
205 
206 		chg += seg_to - seg_from;
207 	}
208 
209 	return chg;
210 }
211 
212 /*
213  * Convert the address within this vma to the page offset within
214  * the mapping, in pagecache page units; huge pages here.
215  */
216 static pgoff_t vma_hugecache_offset(struct hstate *h,
217 			struct vm_area_struct *vma, unsigned long address)
218 {
219 	return ((address - vma->vm_start) >> huge_page_shift(h)) +
220 			(vma->vm_pgoff >> huge_page_order(h));
221 }
222 
223 /*
224  * Return the size of the pages allocated when backing a VMA. In the majority
225  * cases this will be same size as used by the page table entries.
226  */
227 unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
228 {
229 	struct hstate *hstate;
230 
231 	if (!is_vm_hugetlb_page(vma))
232 		return PAGE_SIZE;
233 
234 	hstate = hstate_vma(vma);
235 
236 	return 1UL << (hstate->order + PAGE_SHIFT);
237 }
238 EXPORT_SYMBOL_GPL(vma_kernel_pagesize);
239 
240 /*
241  * Return the page size being used by the MMU to back a VMA. In the majority
242  * of cases, the page size used by the kernel matches the MMU size. On
243  * architectures where it differs, an architecture-specific version of this
244  * function is required.
245  */
246 #ifndef vma_mmu_pagesize
247 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
248 {
249 	return vma_kernel_pagesize(vma);
250 }
251 #endif
252 
253 /*
254  * Flags for MAP_PRIVATE reservations.  These are stored in the bottom
255  * bits of the reservation map pointer, which are always clear due to
256  * alignment.
257  */
258 #define HPAGE_RESV_OWNER    (1UL << 0)
259 #define HPAGE_RESV_UNMAPPED (1UL << 1)
260 #define HPAGE_RESV_MASK (HPAGE_RESV_OWNER | HPAGE_RESV_UNMAPPED)
261 
262 /*
263  * These helpers are used to track how many pages are reserved for
264  * faults in a MAP_PRIVATE mapping. Only the process that called mmap()
265  * is guaranteed to have their future faults succeed.
266  *
267  * With the exception of reset_vma_resv_huge_pages() which is called at fork(),
268  * the reserve counters are updated with the hugetlb_lock held. It is safe
269  * to reset the VMA at fork() time as it is not in use yet and there is no
270  * chance of the global counters getting corrupted as a result of the values.
271  *
272  * The private mapping reservation is represented in a subtly different
273  * manner to a shared mapping.  A shared mapping has a region map associated
274  * with the underlying file, this region map represents the backing file
275  * pages which have ever had a reservation assigned which this persists even
276  * after the page is instantiated.  A private mapping has a region map
277  * associated with the original mmap which is attached to all VMAs which
278  * reference it, this region map represents those offsets which have consumed
279  * reservation ie. where pages have been instantiated.
280  */
281 static unsigned long get_vma_private_data(struct vm_area_struct *vma)
282 {
283 	return (unsigned long)vma->vm_private_data;
284 }
285 
286 static void set_vma_private_data(struct vm_area_struct *vma,
287 							unsigned long value)
288 {
289 	vma->vm_private_data = (void *)value;
290 }
291 
292 struct resv_map {
293 	struct kref refs;
294 	struct list_head regions;
295 };
296 
297 static struct resv_map *resv_map_alloc(void)
298 {
299 	struct resv_map *resv_map = kmalloc(sizeof(*resv_map), GFP_KERNEL);
300 	if (!resv_map)
301 		return NULL;
302 
303 	kref_init(&resv_map->refs);
304 	INIT_LIST_HEAD(&resv_map->regions);
305 
306 	return resv_map;
307 }
308 
309 static void resv_map_release(struct kref *ref)
310 {
311 	struct resv_map *resv_map = container_of(ref, struct resv_map, refs);
312 
313 	/* Clear out any active regions before we release the map. */
314 	region_truncate(&resv_map->regions, 0);
315 	kfree(resv_map);
316 }
317 
318 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
319 {
320 	VM_BUG_ON(!is_vm_hugetlb_page(vma));
321 	if (!(vma->vm_flags & VM_MAYSHARE))
322 		return (struct resv_map *)(get_vma_private_data(vma) &
323 							~HPAGE_RESV_MASK);
324 	return NULL;
325 }
326 
327 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
328 {
329 	VM_BUG_ON(!is_vm_hugetlb_page(vma));
330 	VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
331 
332 	set_vma_private_data(vma, (get_vma_private_data(vma) &
333 				HPAGE_RESV_MASK) | (unsigned long)map);
334 }
335 
336 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
337 {
338 	VM_BUG_ON(!is_vm_hugetlb_page(vma));
339 	VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
340 
341 	set_vma_private_data(vma, get_vma_private_data(vma) | flags);
342 }
343 
344 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
345 {
346 	VM_BUG_ON(!is_vm_hugetlb_page(vma));
347 
348 	return (get_vma_private_data(vma) & flag) != 0;
349 }
350 
351 /* Decrement the reserved pages in the hugepage pool by one */
352 static void decrement_hugepage_resv_vma(struct hstate *h,
353 			struct vm_area_struct *vma)
354 {
355 	if (vma->vm_flags & VM_NORESERVE)
356 		return;
357 
358 	if (vma->vm_flags & VM_MAYSHARE) {
359 		/* Shared mappings always use reserves */
360 		h->resv_huge_pages--;
361 	} else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
362 		/*
363 		 * Only the process that called mmap() has reserves for
364 		 * private mappings.
365 		 */
366 		h->resv_huge_pages--;
367 	}
368 }
369 
370 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
371 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
372 {
373 	VM_BUG_ON(!is_vm_hugetlb_page(vma));
374 	if (!(vma->vm_flags & VM_MAYSHARE))
375 		vma->vm_private_data = (void *)0;
376 }
377 
378 /* Returns true if the VMA has associated reserve pages */
379 static int vma_has_reserves(struct vm_area_struct *vma)
380 {
381 	if (vma->vm_flags & VM_MAYSHARE)
382 		return 1;
383 	if (is_vma_resv_set(vma, HPAGE_RESV_OWNER))
384 		return 1;
385 	return 0;
386 }
387 
388 static void clear_gigantic_page(struct page *page,
389 			unsigned long addr, unsigned long sz)
390 {
391 	int i;
392 	struct page *p = page;
393 
394 	might_sleep();
395 	for (i = 0; i < sz/PAGE_SIZE; i++, p = mem_map_next(p, page, i)) {
396 		cond_resched();
397 		clear_user_highpage(p, addr + i * PAGE_SIZE);
398 	}
399 }
400 static void clear_huge_page(struct page *page,
401 			unsigned long addr, unsigned long sz)
402 {
403 	int i;
404 
405 	if (unlikely(sz/PAGE_SIZE > MAX_ORDER_NR_PAGES)) {
406 		clear_gigantic_page(page, addr, sz);
407 		return;
408 	}
409 
410 	might_sleep();
411 	for (i = 0; i < sz/PAGE_SIZE; i++) {
412 		cond_resched();
413 		clear_user_highpage(page + i, addr + i * PAGE_SIZE);
414 	}
415 }
416 
417 static void copy_gigantic_page(struct page *dst, struct page *src,
418 			   unsigned long addr, struct vm_area_struct *vma)
419 {
420 	int i;
421 	struct hstate *h = hstate_vma(vma);
422 	struct page *dst_base = dst;
423 	struct page *src_base = src;
424 	might_sleep();
425 	for (i = 0; i < pages_per_huge_page(h); ) {
426 		cond_resched();
427 		copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
428 
429 		i++;
430 		dst = mem_map_next(dst, dst_base, i);
431 		src = mem_map_next(src, src_base, i);
432 	}
433 }
434 static void copy_huge_page(struct page *dst, struct page *src,
435 			   unsigned long addr, struct vm_area_struct *vma)
436 {
437 	int i;
438 	struct hstate *h = hstate_vma(vma);
439 
440 	if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
441 		copy_gigantic_page(dst, src, addr, vma);
442 		return;
443 	}
444 
445 	might_sleep();
446 	for (i = 0; i < pages_per_huge_page(h); i++) {
447 		cond_resched();
448 		copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
449 	}
450 }
451 
452 static void enqueue_huge_page(struct hstate *h, struct page *page)
453 {
454 	int nid = page_to_nid(page);
455 	list_add(&page->lru, &h->hugepage_freelists[nid]);
456 	h->free_huge_pages++;
457 	h->free_huge_pages_node[nid]++;
458 }
459 
460 static struct page *dequeue_huge_page_vma(struct hstate *h,
461 				struct vm_area_struct *vma,
462 				unsigned long address, int avoid_reserve)
463 {
464 	int nid;
465 	struct page *page = NULL;
466 	struct mempolicy *mpol;
467 	nodemask_t *nodemask;
468 	struct zonelist *zonelist = huge_zonelist(vma, address,
469 					htlb_alloc_mask, &mpol, &nodemask);
470 	struct zone *zone;
471 	struct zoneref *z;
472 
473 	/*
474 	 * A child process with MAP_PRIVATE mappings created by their parent
475 	 * have no page reserves. This check ensures that reservations are
476 	 * not "stolen". The child may still get SIGKILLed
477 	 */
478 	if (!vma_has_reserves(vma) &&
479 			h->free_huge_pages - h->resv_huge_pages == 0)
480 		return NULL;
481 
482 	/* If reserves cannot be used, ensure enough pages are in the pool */
483 	if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
484 		return NULL;
485 
486 	for_each_zone_zonelist_nodemask(zone, z, zonelist,
487 						MAX_NR_ZONES - 1, nodemask) {
488 		nid = zone_to_nid(zone);
489 		if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
490 		    !list_empty(&h->hugepage_freelists[nid])) {
491 			page = list_entry(h->hugepage_freelists[nid].next,
492 					  struct page, lru);
493 			list_del(&page->lru);
494 			h->free_huge_pages--;
495 			h->free_huge_pages_node[nid]--;
496 
497 			if (!avoid_reserve)
498 				decrement_hugepage_resv_vma(h, vma);
499 
500 			break;
501 		}
502 	}
503 	mpol_cond_put(mpol);
504 	return page;
505 }
506 
507 static void update_and_free_page(struct hstate *h, struct page *page)
508 {
509 	int i;
510 
511 	VM_BUG_ON(h->order >= MAX_ORDER);
512 
513 	h->nr_huge_pages--;
514 	h->nr_huge_pages_node[page_to_nid(page)]--;
515 	for (i = 0; i < pages_per_huge_page(h); i++) {
516 		page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
517 				1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
518 				1 << PG_private | 1<< PG_writeback);
519 	}
520 	set_compound_page_dtor(page, NULL);
521 	set_page_refcounted(page);
522 	arch_release_hugepage(page);
523 	__free_pages(page, huge_page_order(h));
524 }
525 
526 struct hstate *size_to_hstate(unsigned long size)
527 {
528 	struct hstate *h;
529 
530 	for_each_hstate(h) {
531 		if (huge_page_size(h) == size)
532 			return h;
533 	}
534 	return NULL;
535 }
536 
537 static void free_huge_page(struct page *page)
538 {
539 	/*
540 	 * Can't pass hstate in here because it is called from the
541 	 * compound page destructor.
542 	 */
543 	struct hstate *h = page_hstate(page);
544 	int nid = page_to_nid(page);
545 	struct address_space *mapping;
546 
547 	mapping = (struct address_space *) page_private(page);
548 	set_page_private(page, 0);
549 	BUG_ON(page_count(page));
550 	INIT_LIST_HEAD(&page->lru);
551 
552 	spin_lock(&hugetlb_lock);
553 	if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {
554 		update_and_free_page(h, page);
555 		h->surplus_huge_pages--;
556 		h->surplus_huge_pages_node[nid]--;
557 	} else {
558 		enqueue_huge_page(h, page);
559 	}
560 	spin_unlock(&hugetlb_lock);
561 	if (mapping)
562 		hugetlb_put_quota(mapping, 1);
563 }
564 
565 static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
566 {
567 	set_compound_page_dtor(page, free_huge_page);
568 	spin_lock(&hugetlb_lock);
569 	h->nr_huge_pages++;
570 	h->nr_huge_pages_node[nid]++;
571 	spin_unlock(&hugetlb_lock);
572 	put_page(page); /* free it into the hugepage allocator */
573 }
574 
575 static void prep_compound_gigantic_page(struct page *page, unsigned long order)
576 {
577 	int i;
578 	int nr_pages = 1 << order;
579 	struct page *p = page + 1;
580 
581 	/* we rely on prep_new_huge_page to set the destructor */
582 	set_compound_order(page, order);
583 	__SetPageHead(page);
584 	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
585 		__SetPageTail(p);
586 		p->first_page = page;
587 	}
588 }
589 
590 int PageHuge(struct page *page)
591 {
592 	compound_page_dtor *dtor;
593 
594 	if (!PageCompound(page))
595 		return 0;
596 
597 	page = compound_head(page);
598 	dtor = get_compound_page_dtor(page);
599 
600 	return dtor == free_huge_page;
601 }
602 
603 static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
604 {
605 	struct page *page;
606 
607 	if (h->order >= MAX_ORDER)
608 		return NULL;
609 
610 	page = alloc_pages_exact_node(nid,
611 		htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|
612 						__GFP_REPEAT|__GFP_NOWARN,
613 		huge_page_order(h));
614 	if (page) {
615 		if (arch_prepare_hugepage(page)) {
616 			__free_pages(page, huge_page_order(h));
617 			return NULL;
618 		}
619 		prep_new_huge_page(h, page, nid);
620 	}
621 
622 	return page;
623 }
624 
625 /*
626  * common helper functions for hstate_next_node_to_{alloc|free}.
627  * We may have allocated or freed a huge page based on a different
628  * nodes_allowed previously, so h->next_node_to_{alloc|free} might
629  * be outside of *nodes_allowed.  Ensure that we use an allowed
630  * node for alloc or free.
631  */
632 static int next_node_allowed(int nid, nodemask_t *nodes_allowed)
633 {
634 	nid = next_node(nid, *nodes_allowed);
635 	if (nid == MAX_NUMNODES)
636 		nid = first_node(*nodes_allowed);
637 	VM_BUG_ON(nid >= MAX_NUMNODES);
638 
639 	return nid;
640 }
641 
642 static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
643 {
644 	if (!node_isset(nid, *nodes_allowed))
645 		nid = next_node_allowed(nid, nodes_allowed);
646 	return nid;
647 }
648 
649 /*
650  * returns the previously saved node ["this node"] from which to
651  * allocate a persistent huge page for the pool and advance the
652  * next node from which to allocate, handling wrap at end of node
653  * mask.
654  */
655 static int hstate_next_node_to_alloc(struct hstate *h,
656 					nodemask_t *nodes_allowed)
657 {
658 	int nid;
659 
660 	VM_BUG_ON(!nodes_allowed);
661 
662 	nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
663 	h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
664 
665 	return nid;
666 }
667 
668 static int alloc_fresh_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
669 {
670 	struct page *page;
671 	int start_nid;
672 	int next_nid;
673 	int ret = 0;
674 
675 	start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
676 	next_nid = start_nid;
677 
678 	do {
679 		page = alloc_fresh_huge_page_node(h, next_nid);
680 		if (page) {
681 			ret = 1;
682 			break;
683 		}
684 		next_nid = hstate_next_node_to_alloc(h, nodes_allowed);
685 	} while (next_nid != start_nid);
686 
687 	if (ret)
688 		count_vm_event(HTLB_BUDDY_PGALLOC);
689 	else
690 		count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
691 
692 	return ret;
693 }
694 
695 /*
696  * helper for free_pool_huge_page() - return the previously saved
697  * node ["this node"] from which to free a huge page.  Advance the
698  * next node id whether or not we find a free huge page to free so
699  * that the next attempt to free addresses the next node.
700  */
701 static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
702 {
703 	int nid;
704 
705 	VM_BUG_ON(!nodes_allowed);
706 
707 	nid = get_valid_node_allowed(h->next_nid_to_free, nodes_allowed);
708 	h->next_nid_to_free = next_node_allowed(nid, nodes_allowed);
709 
710 	return nid;
711 }
712 
713 /*
714  * Free huge page from pool from next node to free.
715  * Attempt to keep persistent huge pages more or less
716  * balanced over allowed nodes.
717  * Called with hugetlb_lock locked.
718  */
719 static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed,
720 							 bool acct_surplus)
721 {
722 	int start_nid;
723 	int next_nid;
724 	int ret = 0;
725 
726 	start_nid = hstate_next_node_to_free(h, nodes_allowed);
727 	next_nid = start_nid;
728 
729 	do {
730 		/*
731 		 * If we're returning unused surplus pages, only examine
732 		 * nodes with surplus pages.
733 		 */
734 		if ((!acct_surplus || h->surplus_huge_pages_node[next_nid]) &&
735 		    !list_empty(&h->hugepage_freelists[next_nid])) {
736 			struct page *page =
737 				list_entry(h->hugepage_freelists[next_nid].next,
738 					  struct page, lru);
739 			list_del(&page->lru);
740 			h->free_huge_pages--;
741 			h->free_huge_pages_node[next_nid]--;
742 			if (acct_surplus) {
743 				h->surplus_huge_pages--;
744 				h->surplus_huge_pages_node[next_nid]--;
745 			}
746 			update_and_free_page(h, page);
747 			ret = 1;
748 			break;
749 		}
750 		next_nid = hstate_next_node_to_free(h, nodes_allowed);
751 	} while (next_nid != start_nid);
752 
753 	return ret;
754 }
755 
756 static struct page *alloc_buddy_huge_page(struct hstate *h,
757 			struct vm_area_struct *vma, unsigned long address)
758 {
759 	struct page *page;
760 	unsigned int nid;
761 
762 	if (h->order >= MAX_ORDER)
763 		return NULL;
764 
765 	/*
766 	 * Assume we will successfully allocate the surplus page to
767 	 * prevent racing processes from causing the surplus to exceed
768 	 * overcommit
769 	 *
770 	 * This however introduces a different race, where a process B
771 	 * tries to grow the static hugepage pool while alloc_pages() is
772 	 * called by process A. B will only examine the per-node
773 	 * counters in determining if surplus huge pages can be
774 	 * converted to normal huge pages in adjust_pool_surplus(). A
775 	 * won't be able to increment the per-node counter, until the
776 	 * lock is dropped by B, but B doesn't drop hugetlb_lock until
777 	 * no more huge pages can be converted from surplus to normal
778 	 * state (and doesn't try to convert again). Thus, we have a
779 	 * case where a surplus huge page exists, the pool is grown, and
780 	 * the surplus huge page still exists after, even though it
781 	 * should just have been converted to a normal huge page. This
782 	 * does not leak memory, though, as the hugepage will be freed
783 	 * once it is out of use. It also does not allow the counters to
784 	 * go out of whack in adjust_pool_surplus() as we don't modify
785 	 * the node values until we've gotten the hugepage and only the
786 	 * per-node value is checked there.
787 	 */
788 	spin_lock(&hugetlb_lock);
789 	if (h->surplus_huge_pages >= h->nr_overcommit_huge_pages) {
790 		spin_unlock(&hugetlb_lock);
791 		return NULL;
792 	} else {
793 		h->nr_huge_pages++;
794 		h->surplus_huge_pages++;
795 	}
796 	spin_unlock(&hugetlb_lock);
797 
798 	page = alloc_pages(htlb_alloc_mask|__GFP_COMP|
799 					__GFP_REPEAT|__GFP_NOWARN,
800 					huge_page_order(h));
801 
802 	if (page && arch_prepare_hugepage(page)) {
803 		__free_pages(page, huge_page_order(h));
804 		return NULL;
805 	}
806 
807 	spin_lock(&hugetlb_lock);
808 	if (page) {
809 		/*
810 		 * This page is now managed by the hugetlb allocator and has
811 		 * no users -- drop the buddy allocator's reference.
812 		 */
813 		put_page_testzero(page);
814 		VM_BUG_ON(page_count(page));
815 		nid = page_to_nid(page);
816 		set_compound_page_dtor(page, free_huge_page);
817 		/*
818 		 * We incremented the global counters already
819 		 */
820 		h->nr_huge_pages_node[nid]++;
821 		h->surplus_huge_pages_node[nid]++;
822 		__count_vm_event(HTLB_BUDDY_PGALLOC);
823 	} else {
824 		h->nr_huge_pages--;
825 		h->surplus_huge_pages--;
826 		__count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
827 	}
828 	spin_unlock(&hugetlb_lock);
829 
830 	return page;
831 }
832 
833 /*
834  * Increase the hugetlb pool such that it can accomodate a reservation
835  * of size 'delta'.
836  */
837 static int gather_surplus_pages(struct hstate *h, int delta)
838 {
839 	struct list_head surplus_list;
840 	struct page *page, *tmp;
841 	int ret, i;
842 	int needed, allocated;
843 
844 	needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
845 	if (needed <= 0) {
846 		h->resv_huge_pages += delta;
847 		return 0;
848 	}
849 
850 	allocated = 0;
851 	INIT_LIST_HEAD(&surplus_list);
852 
853 	ret = -ENOMEM;
854 retry:
855 	spin_unlock(&hugetlb_lock);
856 	for (i = 0; i < needed; i++) {
857 		page = alloc_buddy_huge_page(h, NULL, 0);
858 		if (!page) {
859 			/*
860 			 * We were not able to allocate enough pages to
861 			 * satisfy the entire reservation so we free what
862 			 * we've allocated so far.
863 			 */
864 			spin_lock(&hugetlb_lock);
865 			needed = 0;
866 			goto free;
867 		}
868 
869 		list_add(&page->lru, &surplus_list);
870 	}
871 	allocated += needed;
872 
873 	/*
874 	 * After retaking hugetlb_lock, we need to recalculate 'needed'
875 	 * because either resv_huge_pages or free_huge_pages may have changed.
876 	 */
877 	spin_lock(&hugetlb_lock);
878 	needed = (h->resv_huge_pages + delta) -
879 			(h->free_huge_pages + allocated);
880 	if (needed > 0)
881 		goto retry;
882 
883 	/*
884 	 * The surplus_list now contains _at_least_ the number of extra pages
885 	 * needed to accomodate the reservation.  Add the appropriate number
886 	 * of pages to the hugetlb pool and free the extras back to the buddy
887 	 * allocator.  Commit the entire reservation here to prevent another
888 	 * process from stealing the pages as they are added to the pool but
889 	 * before they are reserved.
890 	 */
891 	needed += allocated;
892 	h->resv_huge_pages += delta;
893 	ret = 0;
894 free:
895 	/* Free the needed pages to the hugetlb pool */
896 	list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
897 		if ((--needed) < 0)
898 			break;
899 		list_del(&page->lru);
900 		enqueue_huge_page(h, page);
901 	}
902 
903 	/* Free unnecessary surplus pages to the buddy allocator */
904 	if (!list_empty(&surplus_list)) {
905 		spin_unlock(&hugetlb_lock);
906 		list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
907 			list_del(&page->lru);
908 			/*
909 			 * The page has a reference count of zero already, so
910 			 * call free_huge_page directly instead of using
911 			 * put_page.  This must be done with hugetlb_lock
912 			 * unlocked which is safe because free_huge_page takes
913 			 * hugetlb_lock before deciding how to free the page.
914 			 */
915 			free_huge_page(page);
916 		}
917 		spin_lock(&hugetlb_lock);
918 	}
919 
920 	return ret;
921 }
922 
923 /*
924  * When releasing a hugetlb pool reservation, any surplus pages that were
925  * allocated to satisfy the reservation must be explicitly freed if they were
926  * never used.
927  * Called with hugetlb_lock held.
928  */
929 static void return_unused_surplus_pages(struct hstate *h,
930 					unsigned long unused_resv_pages)
931 {
932 	unsigned long nr_pages;
933 
934 	/* Uncommit the reservation */
935 	h->resv_huge_pages -= unused_resv_pages;
936 
937 	/* Cannot return gigantic pages currently */
938 	if (h->order >= MAX_ORDER)
939 		return;
940 
941 	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
942 
943 	/*
944 	 * We want to release as many surplus pages as possible, spread
945 	 * evenly across all nodes with memory. Iterate across these nodes
946 	 * until we can no longer free unreserved surplus pages. This occurs
947 	 * when the nodes with surplus pages have no free pages.
948 	 * free_pool_huge_page() will balance the the freed pages across the
949 	 * on-line nodes with memory and will handle the hstate accounting.
950 	 */
951 	while (nr_pages--) {
952 		if (!free_pool_huge_page(h, &node_states[N_HIGH_MEMORY], 1))
953 			break;
954 	}
955 }
956 
957 /*
958  * Determine if the huge page at addr within the vma has an associated
959  * reservation.  Where it does not we will need to logically increase
960  * reservation and actually increase quota before an allocation can occur.
961  * Where any new reservation would be required the reservation change is
962  * prepared, but not committed.  Once the page has been quota'd allocated
963  * an instantiated the change should be committed via vma_commit_reservation.
964  * No action is required on failure.
965  */
966 static long vma_needs_reservation(struct hstate *h,
967 			struct vm_area_struct *vma, unsigned long addr)
968 {
969 	struct address_space *mapping = vma->vm_file->f_mapping;
970 	struct inode *inode = mapping->host;
971 
972 	if (vma->vm_flags & VM_MAYSHARE) {
973 		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
974 		return region_chg(&inode->i_mapping->private_list,
975 							idx, idx + 1);
976 
977 	} else if (!is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
978 		return 1;
979 
980 	} else  {
981 		long err;
982 		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
983 		struct resv_map *reservations = vma_resv_map(vma);
984 
985 		err = region_chg(&reservations->regions, idx, idx + 1);
986 		if (err < 0)
987 			return err;
988 		return 0;
989 	}
990 }
991 static void vma_commit_reservation(struct hstate *h,
992 			struct vm_area_struct *vma, unsigned long addr)
993 {
994 	struct address_space *mapping = vma->vm_file->f_mapping;
995 	struct inode *inode = mapping->host;
996 
997 	if (vma->vm_flags & VM_MAYSHARE) {
998 		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
999 		region_add(&inode->i_mapping->private_list, idx, idx + 1);
1000 
1001 	} else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
1002 		pgoff_t idx = vma_hugecache_offset(h, vma, addr);
1003 		struct resv_map *reservations = vma_resv_map(vma);
1004 
1005 		/* Mark this page used in the map. */
1006 		region_add(&reservations->regions, idx, idx + 1);
1007 	}
1008 }
1009 
1010 static struct page *alloc_huge_page(struct vm_area_struct *vma,
1011 				    unsigned long addr, int avoid_reserve)
1012 {
1013 	struct hstate *h = hstate_vma(vma);
1014 	struct page *page;
1015 	struct address_space *mapping = vma->vm_file->f_mapping;
1016 	struct inode *inode = mapping->host;
1017 	long chg;
1018 
1019 	/*
1020 	 * Processes that did not create the mapping will have no reserves and
1021 	 * will not have accounted against quota. Check that the quota can be
1022 	 * made before satisfying the allocation
1023 	 * MAP_NORESERVE mappings may also need pages and quota allocated
1024 	 * if no reserve mapping overlaps.
1025 	 */
1026 	chg = vma_needs_reservation(h, vma, addr);
1027 	if (chg < 0)
1028 		return ERR_PTR(chg);
1029 	if (chg)
1030 		if (hugetlb_get_quota(inode->i_mapping, chg))
1031 			return ERR_PTR(-ENOSPC);
1032 
1033 	spin_lock(&hugetlb_lock);
1034 	page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve);
1035 	spin_unlock(&hugetlb_lock);
1036 
1037 	if (!page) {
1038 		page = alloc_buddy_huge_page(h, vma, addr);
1039 		if (!page) {
1040 			hugetlb_put_quota(inode->i_mapping, chg);
1041 			return ERR_PTR(-VM_FAULT_OOM);
1042 		}
1043 	}
1044 
1045 	set_page_refcounted(page);
1046 	set_page_private(page, (unsigned long) mapping);
1047 
1048 	vma_commit_reservation(h, vma, addr);
1049 
1050 	return page;
1051 }
1052 
1053 int __weak alloc_bootmem_huge_page(struct hstate *h)
1054 {
1055 	struct huge_bootmem_page *m;
1056 	int nr_nodes = nodes_weight(node_states[N_HIGH_MEMORY]);
1057 
1058 	while (nr_nodes) {
1059 		void *addr;
1060 
1061 		addr = __alloc_bootmem_node_nopanic(
1062 				NODE_DATA(hstate_next_node_to_alloc(h,
1063 						&node_states[N_HIGH_MEMORY])),
1064 				huge_page_size(h), huge_page_size(h), 0);
1065 
1066 		if (addr) {
1067 			/*
1068 			 * Use the beginning of the huge page to store the
1069 			 * huge_bootmem_page struct (until gather_bootmem
1070 			 * puts them into the mem_map).
1071 			 */
1072 			m = addr;
1073 			goto found;
1074 		}
1075 		nr_nodes--;
1076 	}
1077 	return 0;
1078 
1079 found:
1080 	BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));
1081 	/* Put them into a private list first because mem_map is not up yet */
1082 	list_add(&m->list, &huge_boot_pages);
1083 	m->hstate = h;
1084 	return 1;
1085 }
1086 
1087 static void prep_compound_huge_page(struct page *page, int order)
1088 {
1089 	if (unlikely(order > (MAX_ORDER - 1)))
1090 		prep_compound_gigantic_page(page, order);
1091 	else
1092 		prep_compound_page(page, order);
1093 }
1094 
1095 /* Put bootmem huge pages into the standard lists after mem_map is up */
1096 static void __init gather_bootmem_prealloc(void)
1097 {
1098 	struct huge_bootmem_page *m;
1099 
1100 	list_for_each_entry(m, &huge_boot_pages, list) {
1101 		struct page *page = virt_to_page(m);
1102 		struct hstate *h = m->hstate;
1103 		__ClearPageReserved(page);
1104 		WARN_ON(page_count(page) != 1);
1105 		prep_compound_huge_page(page, h->order);
1106 		prep_new_huge_page(h, page, page_to_nid(page));
1107 	}
1108 }
1109 
1110 static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
1111 {
1112 	unsigned long i;
1113 
1114 	for (i = 0; i < h->max_huge_pages; ++i) {
1115 		if (h->order >= MAX_ORDER) {
1116 			if (!alloc_bootmem_huge_page(h))
1117 				break;
1118 		} else if (!alloc_fresh_huge_page(h,
1119 					 &node_states[N_HIGH_MEMORY]))
1120 			break;
1121 	}
1122 	h->max_huge_pages = i;
1123 }
1124 
1125 static void __init hugetlb_init_hstates(void)
1126 {
1127 	struct hstate *h;
1128 
1129 	for_each_hstate(h) {
1130 		/* oversize hugepages were init'ed in early boot */
1131 		if (h->order < MAX_ORDER)
1132 			hugetlb_hstate_alloc_pages(h);
1133 	}
1134 }
1135 
1136 static char * __init memfmt(char *buf, unsigned long n)
1137 {
1138 	if (n >= (1UL << 30))
1139 		sprintf(buf, "%lu GB", n >> 30);
1140 	else if (n >= (1UL << 20))
1141 		sprintf(buf, "%lu MB", n >> 20);
1142 	else
1143 		sprintf(buf, "%lu KB", n >> 10);
1144 	return buf;
1145 }
1146 
1147 static void __init report_hugepages(void)
1148 {
1149 	struct hstate *h;
1150 
1151 	for_each_hstate(h) {
1152 		char buf[32];
1153 		printk(KERN_INFO "HugeTLB registered %s page size, "
1154 				 "pre-allocated %ld pages\n",
1155 			memfmt(buf, huge_page_size(h)),
1156 			h->free_huge_pages);
1157 	}
1158 }
1159 
1160 #ifdef CONFIG_HIGHMEM
1161 static void try_to_free_low(struct hstate *h, unsigned long count,
1162 						nodemask_t *nodes_allowed)
1163 {
1164 	int i;
1165 
1166 	if (h->order >= MAX_ORDER)
1167 		return;
1168 
1169 	for_each_node_mask(i, *nodes_allowed) {
1170 		struct page *page, *next;
1171 		struct list_head *freel = &h->hugepage_freelists[i];
1172 		list_for_each_entry_safe(page, next, freel, lru) {
1173 			if (count >= h->nr_huge_pages)
1174 				return;
1175 			if (PageHighMem(page))
1176 				continue;
1177 			list_del(&page->lru);
1178 			update_and_free_page(h, page);
1179 			h->free_huge_pages--;
1180 			h->free_huge_pages_node[page_to_nid(page)]--;
1181 		}
1182 	}
1183 }
1184 #else
1185 static inline void try_to_free_low(struct hstate *h, unsigned long count,
1186 						nodemask_t *nodes_allowed)
1187 {
1188 }
1189 #endif
1190 
1191 /*
1192  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
1193  * balanced by operating on them in a round-robin fashion.
1194  * Returns 1 if an adjustment was made.
1195  */
1196 static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
1197 				int delta)
1198 {
1199 	int start_nid, next_nid;
1200 	int ret = 0;
1201 
1202 	VM_BUG_ON(delta != -1 && delta != 1);
1203 
1204 	if (delta < 0)
1205 		start_nid = hstate_next_node_to_alloc(h, nodes_allowed);
1206 	else
1207 		start_nid = hstate_next_node_to_free(h, nodes_allowed);
1208 	next_nid = start_nid;
1209 
1210 	do {
1211 		int nid = next_nid;
1212 		if (delta < 0)  {
1213 			/*
1214 			 * To shrink on this node, there must be a surplus page
1215 			 */
1216 			if (!h->surplus_huge_pages_node[nid]) {
1217 				next_nid = hstate_next_node_to_alloc(h,
1218 								nodes_allowed);
1219 				continue;
1220 			}
1221 		}
1222 		if (delta > 0) {
1223 			/*
1224 			 * Surplus cannot exceed the total number of pages
1225 			 */
1226 			if (h->surplus_huge_pages_node[nid] >=
1227 						h->nr_huge_pages_node[nid]) {
1228 				next_nid = hstate_next_node_to_free(h,
1229 								nodes_allowed);
1230 				continue;
1231 			}
1232 		}
1233 
1234 		h->surplus_huge_pages += delta;
1235 		h->surplus_huge_pages_node[nid] += delta;
1236 		ret = 1;
1237 		break;
1238 	} while (next_nid != start_nid);
1239 
1240 	return ret;
1241 }
1242 
1243 #define persistent_huge_pages(h) (h->nr_huge_pages - h->surplus_huge_pages)
1244 static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count,
1245 						nodemask_t *nodes_allowed)
1246 {
1247 	unsigned long min_count, ret;
1248 
1249 	if (h->order >= MAX_ORDER)
1250 		return h->max_huge_pages;
1251 
1252 	/*
1253 	 * Increase the pool size
1254 	 * First take pages out of surplus state.  Then make up the
1255 	 * remaining difference by allocating fresh huge pages.
1256 	 *
1257 	 * We might race with alloc_buddy_huge_page() here and be unable
1258 	 * to convert a surplus huge page to a normal huge page. That is
1259 	 * not critical, though, it just means the overall size of the
1260 	 * pool might be one hugepage larger than it needs to be, but
1261 	 * within all the constraints specified by the sysctls.
1262 	 */
1263 	spin_lock(&hugetlb_lock);
1264 	while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
1265 		if (!adjust_pool_surplus(h, nodes_allowed, -1))
1266 			break;
1267 	}
1268 
1269 	while (count > persistent_huge_pages(h)) {
1270 		/*
1271 		 * If this allocation races such that we no longer need the
1272 		 * page, free_huge_page will handle it by freeing the page
1273 		 * and reducing the surplus.
1274 		 */
1275 		spin_unlock(&hugetlb_lock);
1276 		ret = alloc_fresh_huge_page(h, nodes_allowed);
1277 		spin_lock(&hugetlb_lock);
1278 		if (!ret)
1279 			goto out;
1280 
1281 		/* Bail for signals. Probably ctrl-c from user */
1282 		if (signal_pending(current))
1283 			goto out;
1284 	}
1285 
1286 	/*
1287 	 * Decrease the pool size
1288 	 * First return free pages to the buddy allocator (being careful
1289 	 * to keep enough around to satisfy reservations).  Then place
1290 	 * pages into surplus state as needed so the pool will shrink
1291 	 * to the desired size as pages become free.
1292 	 *
1293 	 * By placing pages into the surplus state independent of the
1294 	 * overcommit value, we are allowing the surplus pool size to
1295 	 * exceed overcommit. There are few sane options here. Since
1296 	 * alloc_buddy_huge_page() is checking the global counter,
1297 	 * though, we'll note that we're not allowed to exceed surplus
1298 	 * and won't grow the pool anywhere else. Not until one of the
1299 	 * sysctls are changed, or the surplus pages go out of use.
1300 	 */
1301 	min_count = h->resv_huge_pages + h->nr_huge_pages - h->free_huge_pages;
1302 	min_count = max(count, min_count);
1303 	try_to_free_low(h, min_count, nodes_allowed);
1304 	while (min_count < persistent_huge_pages(h)) {
1305 		if (!free_pool_huge_page(h, nodes_allowed, 0))
1306 			break;
1307 	}
1308 	while (count < persistent_huge_pages(h)) {
1309 		if (!adjust_pool_surplus(h, nodes_allowed, 1))
1310 			break;
1311 	}
1312 out:
1313 	ret = persistent_huge_pages(h);
1314 	spin_unlock(&hugetlb_lock);
1315 	return ret;
1316 }
1317 
1318 #define HSTATE_ATTR_RO(_name) \
1319 	static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
1320 
1321 #define HSTATE_ATTR(_name) \
1322 	static struct kobj_attribute _name##_attr = \
1323 		__ATTR(_name, 0644, _name##_show, _name##_store)
1324 
1325 static struct kobject *hugepages_kobj;
1326 static struct kobject *hstate_kobjs[HUGE_MAX_HSTATE];
1327 
1328 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp);
1329 
1330 static struct hstate *kobj_to_hstate(struct kobject *kobj, int *nidp)
1331 {
1332 	int i;
1333 
1334 	for (i = 0; i < HUGE_MAX_HSTATE; i++)
1335 		if (hstate_kobjs[i] == kobj) {
1336 			if (nidp)
1337 				*nidp = NUMA_NO_NODE;
1338 			return &hstates[i];
1339 		}
1340 
1341 	return kobj_to_node_hstate(kobj, nidp);
1342 }
1343 
1344 static ssize_t nr_hugepages_show_common(struct kobject *kobj,
1345 					struct kobj_attribute *attr, char *buf)
1346 {
1347 	struct hstate *h;
1348 	unsigned long nr_huge_pages;
1349 	int nid;
1350 
1351 	h = kobj_to_hstate(kobj, &nid);
1352 	if (nid == NUMA_NO_NODE)
1353 		nr_huge_pages = h->nr_huge_pages;
1354 	else
1355 		nr_huge_pages = h->nr_huge_pages_node[nid];
1356 
1357 	return sprintf(buf, "%lu\n", nr_huge_pages);
1358 }
1359 static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
1360 			struct kobject *kobj, struct kobj_attribute *attr,
1361 			const char *buf, size_t len)
1362 {
1363 	int err;
1364 	int nid;
1365 	unsigned long count;
1366 	struct hstate *h;
1367 	NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
1368 
1369 	err = strict_strtoul(buf, 10, &count);
1370 	if (err)
1371 		return 0;
1372 
1373 	h = kobj_to_hstate(kobj, &nid);
1374 	if (nid == NUMA_NO_NODE) {
1375 		/*
1376 		 * global hstate attribute
1377 		 */
1378 		if (!(obey_mempolicy &&
1379 				init_nodemask_of_mempolicy(nodes_allowed))) {
1380 			NODEMASK_FREE(nodes_allowed);
1381 			nodes_allowed = &node_states[N_HIGH_MEMORY];
1382 		}
1383 	} else if (nodes_allowed) {
1384 		/*
1385 		 * per node hstate attribute: adjust count to global,
1386 		 * but restrict alloc/free to the specified node.
1387 		 */
1388 		count += h->nr_huge_pages - h->nr_huge_pages_node[nid];
1389 		init_nodemask_of_node(nodes_allowed, nid);
1390 	} else
1391 		nodes_allowed = &node_states[N_HIGH_MEMORY];
1392 
1393 	h->max_huge_pages = set_max_huge_pages(h, count, nodes_allowed);
1394 
1395 	if (nodes_allowed != &node_states[N_HIGH_MEMORY])
1396 		NODEMASK_FREE(nodes_allowed);
1397 
1398 	return len;
1399 }
1400 
1401 static ssize_t nr_hugepages_show(struct kobject *kobj,
1402 				       struct kobj_attribute *attr, char *buf)
1403 {
1404 	return nr_hugepages_show_common(kobj, attr, buf);
1405 }
1406 
1407 static ssize_t nr_hugepages_store(struct kobject *kobj,
1408 	       struct kobj_attribute *attr, const char *buf, size_t len)
1409 {
1410 	return nr_hugepages_store_common(false, kobj, attr, buf, len);
1411 }
1412 HSTATE_ATTR(nr_hugepages);
1413 
1414 #ifdef CONFIG_NUMA
1415 
1416 /*
1417  * hstate attribute for optionally mempolicy-based constraint on persistent
1418  * huge page alloc/free.
1419  */
1420 static ssize_t nr_hugepages_mempolicy_show(struct kobject *kobj,
1421 				       struct kobj_attribute *attr, char *buf)
1422 {
1423 	return nr_hugepages_show_common(kobj, attr, buf);
1424 }
1425 
1426 static ssize_t nr_hugepages_mempolicy_store(struct kobject *kobj,
1427 	       struct kobj_attribute *attr, const char *buf, size_t len)
1428 {
1429 	return nr_hugepages_store_common(true, kobj, attr, buf, len);
1430 }
1431 HSTATE_ATTR(nr_hugepages_mempolicy);
1432 #endif
1433 
1434 
1435 static ssize_t nr_overcommit_hugepages_show(struct kobject *kobj,
1436 					struct kobj_attribute *attr, char *buf)
1437 {
1438 	struct hstate *h = kobj_to_hstate(kobj, NULL);
1439 	return sprintf(buf, "%lu\n", h->nr_overcommit_huge_pages);
1440 }
1441 static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
1442 		struct kobj_attribute *attr, const char *buf, size_t count)
1443 {
1444 	int err;
1445 	unsigned long input;
1446 	struct hstate *h = kobj_to_hstate(kobj, NULL);
1447 
1448 	err = strict_strtoul(buf, 10, &input);
1449 	if (err)
1450 		return 0;
1451 
1452 	spin_lock(&hugetlb_lock);
1453 	h->nr_overcommit_huge_pages = input;
1454 	spin_unlock(&hugetlb_lock);
1455 
1456 	return count;
1457 }
1458 HSTATE_ATTR(nr_overcommit_hugepages);
1459 
1460 static ssize_t free_hugepages_show(struct kobject *kobj,
1461 					struct kobj_attribute *attr, char *buf)
1462 {
1463 	struct hstate *h;
1464 	unsigned long free_huge_pages;
1465 	int nid;
1466 
1467 	h = kobj_to_hstate(kobj, &nid);
1468 	if (nid == NUMA_NO_NODE)
1469 		free_huge_pages = h->free_huge_pages;
1470 	else
1471 		free_huge_pages = h->free_huge_pages_node[nid];
1472 
1473 	return sprintf(buf, "%lu\n", free_huge_pages);
1474 }
1475 HSTATE_ATTR_RO(free_hugepages);
1476 
1477 static ssize_t resv_hugepages_show(struct kobject *kobj,
1478 					struct kobj_attribute *attr, char *buf)
1479 {
1480 	struct hstate *h = kobj_to_hstate(kobj, NULL);
1481 	return sprintf(buf, "%lu\n", h->resv_huge_pages);
1482 }
1483 HSTATE_ATTR_RO(resv_hugepages);
1484 
1485 static ssize_t surplus_hugepages_show(struct kobject *kobj,
1486 					struct kobj_attribute *attr, char *buf)
1487 {
1488 	struct hstate *h;
1489 	unsigned long surplus_huge_pages;
1490 	int nid;
1491 
1492 	h = kobj_to_hstate(kobj, &nid);
1493 	if (nid == NUMA_NO_NODE)
1494 		surplus_huge_pages = h->surplus_huge_pages;
1495 	else
1496 		surplus_huge_pages = h->surplus_huge_pages_node[nid];
1497 
1498 	return sprintf(buf, "%lu\n", surplus_huge_pages);
1499 }
1500 HSTATE_ATTR_RO(surplus_hugepages);
1501 
1502 static struct attribute *hstate_attrs[] = {
1503 	&nr_hugepages_attr.attr,
1504 	&nr_overcommit_hugepages_attr.attr,
1505 	&free_hugepages_attr.attr,
1506 	&resv_hugepages_attr.attr,
1507 	&surplus_hugepages_attr.attr,
1508 #ifdef CONFIG_NUMA
1509 	&nr_hugepages_mempolicy_attr.attr,
1510 #endif
1511 	NULL,
1512 };
1513 
1514 static struct attribute_group hstate_attr_group = {
1515 	.attrs = hstate_attrs,
1516 };
1517 
1518 static int __init hugetlb_sysfs_add_hstate(struct hstate *h,
1519 				struct kobject *parent,
1520 				struct kobject **hstate_kobjs,
1521 				struct attribute_group *hstate_attr_group)
1522 {
1523 	int retval;
1524 	int hi = h - hstates;
1525 
1526 	hstate_kobjs[hi] = kobject_create_and_add(h->name, parent);
1527 	if (!hstate_kobjs[hi])
1528 		return -ENOMEM;
1529 
1530 	retval = sysfs_create_group(hstate_kobjs[hi], hstate_attr_group);
1531 	if (retval)
1532 		kobject_put(hstate_kobjs[hi]);
1533 
1534 	return retval;
1535 }
1536 
1537 static void __init hugetlb_sysfs_init(void)
1538 {
1539 	struct hstate *h;
1540 	int err;
1541 
1542 	hugepages_kobj = kobject_create_and_add("hugepages", mm_kobj);
1543 	if (!hugepages_kobj)
1544 		return;
1545 
1546 	for_each_hstate(h) {
1547 		err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
1548 					 hstate_kobjs, &hstate_attr_group);
1549 		if (err)
1550 			printk(KERN_ERR "Hugetlb: Unable to add hstate %s",
1551 								h->name);
1552 	}
1553 }
1554 
1555 #ifdef CONFIG_NUMA
1556 
1557 /*
1558  * node_hstate/s - associate per node hstate attributes, via their kobjects,
1559  * with node sysdevs in node_devices[] using a parallel array.  The array
1560  * index of a node sysdev or _hstate == node id.
1561  * This is here to avoid any static dependency of the node sysdev driver, in
1562  * the base kernel, on the hugetlb module.
1563  */
1564 struct node_hstate {
1565 	struct kobject		*hugepages_kobj;
1566 	struct kobject		*hstate_kobjs[HUGE_MAX_HSTATE];
1567 };
1568 struct node_hstate node_hstates[MAX_NUMNODES];
1569 
1570 /*
1571  * A subset of global hstate attributes for node sysdevs
1572  */
1573 static struct attribute *per_node_hstate_attrs[] = {
1574 	&nr_hugepages_attr.attr,
1575 	&free_hugepages_attr.attr,
1576 	&surplus_hugepages_attr.attr,
1577 	NULL,
1578 };
1579 
1580 static struct attribute_group per_node_hstate_attr_group = {
1581 	.attrs = per_node_hstate_attrs,
1582 };
1583 
1584 /*
1585  * kobj_to_node_hstate - lookup global hstate for node sysdev hstate attr kobj.
1586  * Returns node id via non-NULL nidp.
1587  */
1588 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1589 {
1590 	int nid;
1591 
1592 	for (nid = 0; nid < nr_node_ids; nid++) {
1593 		struct node_hstate *nhs = &node_hstates[nid];
1594 		int i;
1595 		for (i = 0; i < HUGE_MAX_HSTATE; i++)
1596 			if (nhs->hstate_kobjs[i] == kobj) {
1597 				if (nidp)
1598 					*nidp = nid;
1599 				return &hstates[i];
1600 			}
1601 	}
1602 
1603 	BUG();
1604 	return NULL;
1605 }
1606 
1607 /*
1608  * Unregister hstate attributes from a single node sysdev.
1609  * No-op if no hstate attributes attached.
1610  */
1611 void hugetlb_unregister_node(struct node *node)
1612 {
1613 	struct hstate *h;
1614 	struct node_hstate *nhs = &node_hstates[node->sysdev.id];
1615 
1616 	if (!nhs->hugepages_kobj)
1617 		return;		/* no hstate attributes */
1618 
1619 	for_each_hstate(h)
1620 		if (nhs->hstate_kobjs[h - hstates]) {
1621 			kobject_put(nhs->hstate_kobjs[h - hstates]);
1622 			nhs->hstate_kobjs[h - hstates] = NULL;
1623 		}
1624 
1625 	kobject_put(nhs->hugepages_kobj);
1626 	nhs->hugepages_kobj = NULL;
1627 }
1628 
1629 /*
1630  * hugetlb module exit:  unregister hstate attributes from node sysdevs
1631  * that have them.
1632  */
1633 static void hugetlb_unregister_all_nodes(void)
1634 {
1635 	int nid;
1636 
1637 	/*
1638 	 * disable node sysdev registrations.
1639 	 */
1640 	register_hugetlbfs_with_node(NULL, NULL);
1641 
1642 	/*
1643 	 * remove hstate attributes from any nodes that have them.
1644 	 */
1645 	for (nid = 0; nid < nr_node_ids; nid++)
1646 		hugetlb_unregister_node(&node_devices[nid]);
1647 }
1648 
1649 /*
1650  * Register hstate attributes for a single node sysdev.
1651  * No-op if attributes already registered.
1652  */
1653 void hugetlb_register_node(struct node *node)
1654 {
1655 	struct hstate *h;
1656 	struct node_hstate *nhs = &node_hstates[node->sysdev.id];
1657 	int err;
1658 
1659 	if (nhs->hugepages_kobj)
1660 		return;		/* already allocated */
1661 
1662 	nhs->hugepages_kobj = kobject_create_and_add("hugepages",
1663 							&node->sysdev.kobj);
1664 	if (!nhs->hugepages_kobj)
1665 		return;
1666 
1667 	for_each_hstate(h) {
1668 		err = hugetlb_sysfs_add_hstate(h, nhs->hugepages_kobj,
1669 						nhs->hstate_kobjs,
1670 						&per_node_hstate_attr_group);
1671 		if (err) {
1672 			printk(KERN_ERR "Hugetlb: Unable to add hstate %s"
1673 					" for node %d\n",
1674 						h->name, node->sysdev.id);
1675 			hugetlb_unregister_node(node);
1676 			break;
1677 		}
1678 	}
1679 }
1680 
1681 /*
1682  * hugetlb init time:  register hstate attributes for all registered node
1683  * sysdevs of nodes that have memory.  All on-line nodes should have
1684  * registered their associated sysdev by this time.
1685  */
1686 static void hugetlb_register_all_nodes(void)
1687 {
1688 	int nid;
1689 
1690 	for_each_node_state(nid, N_HIGH_MEMORY) {
1691 		struct node *node = &node_devices[nid];
1692 		if (node->sysdev.id == nid)
1693 			hugetlb_register_node(node);
1694 	}
1695 
1696 	/*
1697 	 * Let the node sysdev driver know we're here so it can
1698 	 * [un]register hstate attributes on node hotplug.
1699 	 */
1700 	register_hugetlbfs_with_node(hugetlb_register_node,
1701 				     hugetlb_unregister_node);
1702 }
1703 #else	/* !CONFIG_NUMA */
1704 
1705 static struct hstate *kobj_to_node_hstate(struct kobject *kobj, int *nidp)
1706 {
1707 	BUG();
1708 	if (nidp)
1709 		*nidp = -1;
1710 	return NULL;
1711 }
1712 
1713 static void hugetlb_unregister_all_nodes(void) { }
1714 
1715 static void hugetlb_register_all_nodes(void) { }
1716 
1717 #endif
1718 
1719 static void __exit hugetlb_exit(void)
1720 {
1721 	struct hstate *h;
1722 
1723 	hugetlb_unregister_all_nodes();
1724 
1725 	for_each_hstate(h) {
1726 		kobject_put(hstate_kobjs[h - hstates]);
1727 	}
1728 
1729 	kobject_put(hugepages_kobj);
1730 }
1731 module_exit(hugetlb_exit);
1732 
1733 static int __init hugetlb_init(void)
1734 {
1735 	/* Some platform decide whether they support huge pages at boot
1736 	 * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when
1737 	 * there is no such support
1738 	 */
1739 	if (HPAGE_SHIFT == 0)
1740 		return 0;
1741 
1742 	if (!size_to_hstate(default_hstate_size)) {
1743 		default_hstate_size = HPAGE_SIZE;
1744 		if (!size_to_hstate(default_hstate_size))
1745 			hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
1746 	}
1747 	default_hstate_idx = size_to_hstate(default_hstate_size) - hstates;
1748 	if (default_hstate_max_huge_pages)
1749 		default_hstate.max_huge_pages = default_hstate_max_huge_pages;
1750 
1751 	hugetlb_init_hstates();
1752 
1753 	gather_bootmem_prealloc();
1754 
1755 	report_hugepages();
1756 
1757 	hugetlb_sysfs_init();
1758 
1759 	hugetlb_register_all_nodes();
1760 
1761 	return 0;
1762 }
1763 module_init(hugetlb_init);
1764 
1765 /* Should be called on processing a hugepagesz=... option */
1766 void __init hugetlb_add_hstate(unsigned order)
1767 {
1768 	struct hstate *h;
1769 	unsigned long i;
1770 
1771 	if (size_to_hstate(PAGE_SIZE << order)) {
1772 		printk(KERN_WARNING "hugepagesz= specified twice, ignoring\n");
1773 		return;
1774 	}
1775 	BUG_ON(max_hstate >= HUGE_MAX_HSTATE);
1776 	BUG_ON(order == 0);
1777 	h = &hstates[max_hstate++];
1778 	h->order = order;
1779 	h->mask = ~((1ULL << (order + PAGE_SHIFT)) - 1);
1780 	h->nr_huge_pages = 0;
1781 	h->free_huge_pages = 0;
1782 	for (i = 0; i < MAX_NUMNODES; ++i)
1783 		INIT_LIST_HEAD(&h->hugepage_freelists[i]);
1784 	h->next_nid_to_alloc = first_node(node_states[N_HIGH_MEMORY]);
1785 	h->next_nid_to_free = first_node(node_states[N_HIGH_MEMORY]);
1786 	snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
1787 					huge_page_size(h)/1024);
1788 
1789 	parsed_hstate = h;
1790 }
1791 
1792 static int __init hugetlb_nrpages_setup(char *s)
1793 {
1794 	unsigned long *mhp;
1795 	static unsigned long *last_mhp;
1796 
1797 	/*
1798 	 * !max_hstate means we haven't parsed a hugepagesz= parameter yet,
1799 	 * so this hugepages= parameter goes to the "default hstate".
1800 	 */
1801 	if (!max_hstate)
1802 		mhp = &default_hstate_max_huge_pages;
1803 	else
1804 		mhp = &parsed_hstate->max_huge_pages;
1805 
1806 	if (mhp == last_mhp) {
1807 		printk(KERN_WARNING "hugepages= specified twice without "
1808 			"interleaving hugepagesz=, ignoring\n");
1809 		return 1;
1810 	}
1811 
1812 	if (sscanf(s, "%lu", mhp) <= 0)
1813 		*mhp = 0;
1814 
1815 	/*
1816 	 * Global state is always initialized later in hugetlb_init.
1817 	 * But we need to allocate >= MAX_ORDER hstates here early to still
1818 	 * use the bootmem allocator.
1819 	 */
1820 	if (max_hstate && parsed_hstate->order >= MAX_ORDER)
1821 		hugetlb_hstate_alloc_pages(parsed_hstate);
1822 
1823 	last_mhp = mhp;
1824 
1825 	return 1;
1826 }
1827 __setup("hugepages=", hugetlb_nrpages_setup);
1828 
1829 static int __init hugetlb_default_setup(char *s)
1830 {
1831 	default_hstate_size = memparse(s, &s);
1832 	return 1;
1833 }
1834 __setup("default_hugepagesz=", hugetlb_default_setup);
1835 
1836 static unsigned int cpuset_mems_nr(unsigned int *array)
1837 {
1838 	int node;
1839 	unsigned int nr = 0;
1840 
1841 	for_each_node_mask(node, cpuset_current_mems_allowed)
1842 		nr += array[node];
1843 
1844 	return nr;
1845 }
1846 
1847 #ifdef CONFIG_SYSCTL
1848 static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
1849 			 struct ctl_table *table, int write,
1850 			 void __user *buffer, size_t *length, loff_t *ppos)
1851 {
1852 	struct hstate *h = &default_hstate;
1853 	unsigned long tmp;
1854 
1855 	if (!write)
1856 		tmp = h->max_huge_pages;
1857 
1858 	table->data = &tmp;
1859 	table->maxlen = sizeof(unsigned long);
1860 	proc_doulongvec_minmax(table, write, buffer, length, ppos);
1861 
1862 	if (write) {
1863 		NODEMASK_ALLOC(nodemask_t, nodes_allowed,
1864 						GFP_KERNEL | __GFP_NORETRY);
1865 		if (!(obey_mempolicy &&
1866 			       init_nodemask_of_mempolicy(nodes_allowed))) {
1867 			NODEMASK_FREE(nodes_allowed);
1868 			nodes_allowed = &node_states[N_HIGH_MEMORY];
1869 		}
1870 		h->max_huge_pages = set_max_huge_pages(h, tmp, nodes_allowed);
1871 
1872 		if (nodes_allowed != &node_states[N_HIGH_MEMORY])
1873 			NODEMASK_FREE(nodes_allowed);
1874 	}
1875 
1876 	return 0;
1877 }
1878 
1879 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
1880 			  void __user *buffer, size_t *length, loff_t *ppos)
1881 {
1882 
1883 	return hugetlb_sysctl_handler_common(false, table, write,
1884 							buffer, length, ppos);
1885 }
1886 
1887 #ifdef CONFIG_NUMA
1888 int hugetlb_mempolicy_sysctl_handler(struct ctl_table *table, int write,
1889 			  void __user *buffer, size_t *length, loff_t *ppos)
1890 {
1891 	return hugetlb_sysctl_handler_common(true, table, write,
1892 							buffer, length, ppos);
1893 }
1894 #endif /* CONFIG_NUMA */
1895 
1896 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
1897 			void __user *buffer,
1898 			size_t *length, loff_t *ppos)
1899 {
1900 	proc_dointvec(table, write, buffer, length, ppos);
1901 	if (hugepages_treat_as_movable)
1902 		htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
1903 	else
1904 		htlb_alloc_mask = GFP_HIGHUSER;
1905 	return 0;
1906 }
1907 
1908 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
1909 			void __user *buffer,
1910 			size_t *length, loff_t *ppos)
1911 {
1912 	struct hstate *h = &default_hstate;
1913 	unsigned long tmp;
1914 
1915 	if (!write)
1916 		tmp = h->nr_overcommit_huge_pages;
1917 
1918 	table->data = &tmp;
1919 	table->maxlen = sizeof(unsigned long);
1920 	proc_doulongvec_minmax(table, write, buffer, length, ppos);
1921 
1922 	if (write) {
1923 		spin_lock(&hugetlb_lock);
1924 		h->nr_overcommit_huge_pages = tmp;
1925 		spin_unlock(&hugetlb_lock);
1926 	}
1927 
1928 	return 0;
1929 }
1930 
1931 #endif /* CONFIG_SYSCTL */
1932 
1933 void hugetlb_report_meminfo(struct seq_file *m)
1934 {
1935 	struct hstate *h = &default_hstate;
1936 	seq_printf(m,
1937 			"HugePages_Total:   %5lu\n"
1938 			"HugePages_Free:    %5lu\n"
1939 			"HugePages_Rsvd:    %5lu\n"
1940 			"HugePages_Surp:    %5lu\n"
1941 			"Hugepagesize:   %8lu kB\n",
1942 			h->nr_huge_pages,
1943 			h->free_huge_pages,
1944 			h->resv_huge_pages,
1945 			h->surplus_huge_pages,
1946 			1UL << (huge_page_order(h) + PAGE_SHIFT - 10));
1947 }
1948 
1949 int hugetlb_report_node_meminfo(int nid, char *buf)
1950 {
1951 	struct hstate *h = &default_hstate;
1952 	return sprintf(buf,
1953 		"Node %d HugePages_Total: %5u\n"
1954 		"Node %d HugePages_Free:  %5u\n"
1955 		"Node %d HugePages_Surp:  %5u\n",
1956 		nid, h->nr_huge_pages_node[nid],
1957 		nid, h->free_huge_pages_node[nid],
1958 		nid, h->surplus_huge_pages_node[nid]);
1959 }
1960 
1961 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
1962 unsigned long hugetlb_total_pages(void)
1963 {
1964 	struct hstate *h = &default_hstate;
1965 	return h->nr_huge_pages * pages_per_huge_page(h);
1966 }
1967 
1968 static int hugetlb_acct_memory(struct hstate *h, long delta)
1969 {
1970 	int ret = -ENOMEM;
1971 
1972 	spin_lock(&hugetlb_lock);
1973 	/*
1974 	 * When cpuset is configured, it breaks the strict hugetlb page
1975 	 * reservation as the accounting is done on a global variable. Such
1976 	 * reservation is completely rubbish in the presence of cpuset because
1977 	 * the reservation is not checked against page availability for the
1978 	 * current cpuset. Application can still potentially OOM'ed by kernel
1979 	 * with lack of free htlb page in cpuset that the task is in.
1980 	 * Attempt to enforce strict accounting with cpuset is almost
1981 	 * impossible (or too ugly) because cpuset is too fluid that
1982 	 * task or memory node can be dynamically moved between cpusets.
1983 	 *
1984 	 * The change of semantics for shared hugetlb mapping with cpuset is
1985 	 * undesirable. However, in order to preserve some of the semantics,
1986 	 * we fall back to check against current free page availability as
1987 	 * a best attempt and hopefully to minimize the impact of changing
1988 	 * semantics that cpuset has.
1989 	 */
1990 	if (delta > 0) {
1991 		if (gather_surplus_pages(h, delta) < 0)
1992 			goto out;
1993 
1994 		if (delta > cpuset_mems_nr(h->free_huge_pages_node)) {
1995 			return_unused_surplus_pages(h, delta);
1996 			goto out;
1997 		}
1998 	}
1999 
2000 	ret = 0;
2001 	if (delta < 0)
2002 		return_unused_surplus_pages(h, (unsigned long) -delta);
2003 
2004 out:
2005 	spin_unlock(&hugetlb_lock);
2006 	return ret;
2007 }
2008 
2009 static void hugetlb_vm_op_open(struct vm_area_struct *vma)
2010 {
2011 	struct resv_map *reservations = vma_resv_map(vma);
2012 
2013 	/*
2014 	 * This new VMA should share its siblings reservation map if present.
2015 	 * The VMA will only ever have a valid reservation map pointer where
2016 	 * it is being copied for another still existing VMA.  As that VMA
2017 	 * has a reference to the reservation map it cannot dissappear until
2018 	 * after this open call completes.  It is therefore safe to take a
2019 	 * new reference here without additional locking.
2020 	 */
2021 	if (reservations)
2022 		kref_get(&reservations->refs);
2023 }
2024 
2025 static void hugetlb_vm_op_close(struct vm_area_struct *vma)
2026 {
2027 	struct hstate *h = hstate_vma(vma);
2028 	struct resv_map *reservations = vma_resv_map(vma);
2029 	unsigned long reserve;
2030 	unsigned long start;
2031 	unsigned long end;
2032 
2033 	if (reservations) {
2034 		start = vma_hugecache_offset(h, vma, vma->vm_start);
2035 		end = vma_hugecache_offset(h, vma, vma->vm_end);
2036 
2037 		reserve = (end - start) -
2038 			region_count(&reservations->regions, start, end);
2039 
2040 		kref_put(&reservations->refs, resv_map_release);
2041 
2042 		if (reserve) {
2043 			hugetlb_acct_memory(h, -reserve);
2044 			hugetlb_put_quota(vma->vm_file->f_mapping, reserve);
2045 		}
2046 	}
2047 }
2048 
2049 /*
2050  * We cannot handle pagefaults against hugetlb pages at all.  They cause
2051  * handle_mm_fault() to try to instantiate regular-sized pages in the
2052  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
2053  * this far.
2054  */
2055 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
2056 {
2057 	BUG();
2058 	return 0;
2059 }
2060 
2061 const struct vm_operations_struct hugetlb_vm_ops = {
2062 	.fault = hugetlb_vm_op_fault,
2063 	.open = hugetlb_vm_op_open,
2064 	.close = hugetlb_vm_op_close,
2065 };
2066 
2067 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
2068 				int writable)
2069 {
2070 	pte_t entry;
2071 
2072 	if (writable) {
2073 		entry =
2074 		    pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
2075 	} else {
2076 		entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
2077 	}
2078 	entry = pte_mkyoung(entry);
2079 	entry = pte_mkhuge(entry);
2080 
2081 	return entry;
2082 }
2083 
2084 static void set_huge_ptep_writable(struct vm_area_struct *vma,
2085 				   unsigned long address, pte_t *ptep)
2086 {
2087 	pte_t entry;
2088 
2089 	entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
2090 	if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
2091 		update_mmu_cache(vma, address, entry);
2092 	}
2093 }
2094 
2095 
2096 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
2097 			    struct vm_area_struct *vma)
2098 {
2099 	pte_t *src_pte, *dst_pte, entry;
2100 	struct page *ptepage;
2101 	unsigned long addr;
2102 	int cow;
2103 	struct hstate *h = hstate_vma(vma);
2104 	unsigned long sz = huge_page_size(h);
2105 
2106 	cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
2107 
2108 	for (addr = vma->vm_start; addr < vma->vm_end; addr += sz) {
2109 		src_pte = huge_pte_offset(src, addr);
2110 		if (!src_pte)
2111 			continue;
2112 		dst_pte = huge_pte_alloc(dst, addr, sz);
2113 		if (!dst_pte)
2114 			goto nomem;
2115 
2116 		/* If the pagetables are shared don't copy or take references */
2117 		if (dst_pte == src_pte)
2118 			continue;
2119 
2120 		spin_lock(&dst->page_table_lock);
2121 		spin_lock_nested(&src->page_table_lock, SINGLE_DEPTH_NESTING);
2122 		if (!huge_pte_none(huge_ptep_get(src_pte))) {
2123 			if (cow)
2124 				huge_ptep_set_wrprotect(src, addr, src_pte);
2125 			entry = huge_ptep_get(src_pte);
2126 			ptepage = pte_page(entry);
2127 			get_page(ptepage);
2128 			set_huge_pte_at(dst, addr, dst_pte, entry);
2129 		}
2130 		spin_unlock(&src->page_table_lock);
2131 		spin_unlock(&dst->page_table_lock);
2132 	}
2133 	return 0;
2134 
2135 nomem:
2136 	return -ENOMEM;
2137 }
2138 
2139 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2140 			    unsigned long end, struct page *ref_page)
2141 {
2142 	struct mm_struct *mm = vma->vm_mm;
2143 	unsigned long address;
2144 	pte_t *ptep;
2145 	pte_t pte;
2146 	struct page *page;
2147 	struct page *tmp;
2148 	struct hstate *h = hstate_vma(vma);
2149 	unsigned long sz = huge_page_size(h);
2150 
2151 	/*
2152 	 * A page gathering list, protected by per file i_mmap_lock. The
2153 	 * lock is used to avoid list corruption from multiple unmapping
2154 	 * of the same page since we are using page->lru.
2155 	 */
2156 	LIST_HEAD(page_list);
2157 
2158 	WARN_ON(!is_vm_hugetlb_page(vma));
2159 	BUG_ON(start & ~huge_page_mask(h));
2160 	BUG_ON(end & ~huge_page_mask(h));
2161 
2162 	mmu_notifier_invalidate_range_start(mm, start, end);
2163 	spin_lock(&mm->page_table_lock);
2164 	for (address = start; address < end; address += sz) {
2165 		ptep = huge_pte_offset(mm, address);
2166 		if (!ptep)
2167 			continue;
2168 
2169 		if (huge_pmd_unshare(mm, &address, ptep))
2170 			continue;
2171 
2172 		/*
2173 		 * If a reference page is supplied, it is because a specific
2174 		 * page is being unmapped, not a range. Ensure the page we
2175 		 * are about to unmap is the actual page of interest.
2176 		 */
2177 		if (ref_page) {
2178 			pte = huge_ptep_get(ptep);
2179 			if (huge_pte_none(pte))
2180 				continue;
2181 			page = pte_page(pte);
2182 			if (page != ref_page)
2183 				continue;
2184 
2185 			/*
2186 			 * Mark the VMA as having unmapped its page so that
2187 			 * future faults in this VMA will fail rather than
2188 			 * looking like data was lost
2189 			 */
2190 			set_vma_resv_flags(vma, HPAGE_RESV_UNMAPPED);
2191 		}
2192 
2193 		pte = huge_ptep_get_and_clear(mm, address, ptep);
2194 		if (huge_pte_none(pte))
2195 			continue;
2196 
2197 		page = pte_page(pte);
2198 		if (pte_dirty(pte))
2199 			set_page_dirty(page);
2200 		list_add(&page->lru, &page_list);
2201 	}
2202 	spin_unlock(&mm->page_table_lock);
2203 	flush_tlb_range(vma, start, end);
2204 	mmu_notifier_invalidate_range_end(mm, start, end);
2205 	list_for_each_entry_safe(page, tmp, &page_list, lru) {
2206 		list_del(&page->lru);
2207 		put_page(page);
2208 	}
2209 }
2210 
2211 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
2212 			  unsigned long end, struct page *ref_page)
2213 {
2214 	spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2215 	__unmap_hugepage_range(vma, start, end, ref_page);
2216 	spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2217 }
2218 
2219 /*
2220  * This is called when the original mapper is failing to COW a MAP_PRIVATE
2221  * mappping it owns the reserve page for. The intention is to unmap the page
2222  * from other VMAs and let the children be SIGKILLed if they are faulting the
2223  * same region.
2224  */
2225 static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
2226 				struct page *page, unsigned long address)
2227 {
2228 	struct hstate *h = hstate_vma(vma);
2229 	struct vm_area_struct *iter_vma;
2230 	struct address_space *mapping;
2231 	struct prio_tree_iter iter;
2232 	pgoff_t pgoff;
2233 
2234 	/*
2235 	 * vm_pgoff is in PAGE_SIZE units, hence the different calculation
2236 	 * from page cache lookup which is in HPAGE_SIZE units.
2237 	 */
2238 	address = address & huge_page_mask(h);
2239 	pgoff = ((address - vma->vm_start) >> PAGE_SHIFT)
2240 		+ (vma->vm_pgoff >> PAGE_SHIFT);
2241 	mapping = (struct address_space *)page_private(page);
2242 
2243 	/*
2244 	 * Take the mapping lock for the duration of the table walk. As
2245 	 * this mapping should be shared between all the VMAs,
2246 	 * __unmap_hugepage_range() is called as the lock is already held
2247 	 */
2248 	spin_lock(&mapping->i_mmap_lock);
2249 	vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
2250 		/* Do not unmap the current VMA */
2251 		if (iter_vma == vma)
2252 			continue;
2253 
2254 		/*
2255 		 * Unmap the page from other VMAs without their own reserves.
2256 		 * They get marked to be SIGKILLed if they fault in these
2257 		 * areas. This is because a future no-page fault on this VMA
2258 		 * could insert a zeroed page instead of the data existing
2259 		 * from the time of fork. This would look like data corruption
2260 		 */
2261 		if (!is_vma_resv_set(iter_vma, HPAGE_RESV_OWNER))
2262 			__unmap_hugepage_range(iter_vma,
2263 				address, address + huge_page_size(h),
2264 				page);
2265 	}
2266 	spin_unlock(&mapping->i_mmap_lock);
2267 
2268 	return 1;
2269 }
2270 
2271 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
2272 			unsigned long address, pte_t *ptep, pte_t pte,
2273 			struct page *pagecache_page)
2274 {
2275 	struct hstate *h = hstate_vma(vma);
2276 	struct page *old_page, *new_page;
2277 	int avoidcopy;
2278 	int outside_reserve = 0;
2279 
2280 	old_page = pte_page(pte);
2281 
2282 retry_avoidcopy:
2283 	/* If no-one else is actually using this page, avoid the copy
2284 	 * and just make the page writable */
2285 	avoidcopy = (page_count(old_page) == 1);
2286 	if (avoidcopy) {
2287 		set_huge_ptep_writable(vma, address, ptep);
2288 		return 0;
2289 	}
2290 
2291 	/*
2292 	 * If the process that created a MAP_PRIVATE mapping is about to
2293 	 * perform a COW due to a shared page count, attempt to satisfy
2294 	 * the allocation without using the existing reserves. The pagecache
2295 	 * page is used to determine if the reserve at this address was
2296 	 * consumed or not. If reserves were used, a partial faulted mapping
2297 	 * at the time of fork() could consume its reserves on COW instead
2298 	 * of the full address range.
2299 	 */
2300 	if (!(vma->vm_flags & VM_MAYSHARE) &&
2301 			is_vma_resv_set(vma, HPAGE_RESV_OWNER) &&
2302 			old_page != pagecache_page)
2303 		outside_reserve = 1;
2304 
2305 	page_cache_get(old_page);
2306 
2307 	/* Drop page_table_lock as buddy allocator may be called */
2308 	spin_unlock(&mm->page_table_lock);
2309 	new_page = alloc_huge_page(vma, address, outside_reserve);
2310 
2311 	if (IS_ERR(new_page)) {
2312 		page_cache_release(old_page);
2313 
2314 		/*
2315 		 * If a process owning a MAP_PRIVATE mapping fails to COW,
2316 		 * it is due to references held by a child and an insufficient
2317 		 * huge page pool. To guarantee the original mappers
2318 		 * reliability, unmap the page from child processes. The child
2319 		 * may get SIGKILLed if it later faults.
2320 		 */
2321 		if (outside_reserve) {
2322 			BUG_ON(huge_pte_none(pte));
2323 			if (unmap_ref_private(mm, vma, old_page, address)) {
2324 				BUG_ON(page_count(old_page) != 1);
2325 				BUG_ON(huge_pte_none(pte));
2326 				spin_lock(&mm->page_table_lock);
2327 				goto retry_avoidcopy;
2328 			}
2329 			WARN_ON_ONCE(1);
2330 		}
2331 
2332 		/* Caller expects lock to be held */
2333 		spin_lock(&mm->page_table_lock);
2334 		return -PTR_ERR(new_page);
2335 	}
2336 
2337 	copy_huge_page(new_page, old_page, address, vma);
2338 	__SetPageUptodate(new_page);
2339 
2340 	/*
2341 	 * Retake the page_table_lock to check for racing updates
2342 	 * before the page tables are altered
2343 	 */
2344 	spin_lock(&mm->page_table_lock);
2345 	ptep = huge_pte_offset(mm, address & huge_page_mask(h));
2346 	if (likely(pte_same(huge_ptep_get(ptep), pte))) {
2347 		/* Break COW */
2348 		huge_ptep_clear_flush(vma, address, ptep);
2349 		set_huge_pte_at(mm, address, ptep,
2350 				make_huge_pte(vma, new_page, 1));
2351 		/* Make the old page be freed below */
2352 		new_page = old_page;
2353 	}
2354 	page_cache_release(new_page);
2355 	page_cache_release(old_page);
2356 	return 0;
2357 }
2358 
2359 /* Return the pagecache page at a given address within a VMA */
2360 static struct page *hugetlbfs_pagecache_page(struct hstate *h,
2361 			struct vm_area_struct *vma, unsigned long address)
2362 {
2363 	struct address_space *mapping;
2364 	pgoff_t idx;
2365 
2366 	mapping = vma->vm_file->f_mapping;
2367 	idx = vma_hugecache_offset(h, vma, address);
2368 
2369 	return find_lock_page(mapping, idx);
2370 }
2371 
2372 /*
2373  * Return whether there is a pagecache page to back given address within VMA.
2374  * Caller follow_hugetlb_page() holds page_table_lock so we cannot lock_page.
2375  */
2376 static bool hugetlbfs_pagecache_present(struct hstate *h,
2377 			struct vm_area_struct *vma, unsigned long address)
2378 {
2379 	struct address_space *mapping;
2380 	pgoff_t idx;
2381 	struct page *page;
2382 
2383 	mapping = vma->vm_file->f_mapping;
2384 	idx = vma_hugecache_offset(h, vma, address);
2385 
2386 	page = find_get_page(mapping, idx);
2387 	if (page)
2388 		put_page(page);
2389 	return page != NULL;
2390 }
2391 
2392 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
2393 			unsigned long address, pte_t *ptep, unsigned int flags)
2394 {
2395 	struct hstate *h = hstate_vma(vma);
2396 	int ret = VM_FAULT_SIGBUS;
2397 	pgoff_t idx;
2398 	unsigned long size;
2399 	struct page *page;
2400 	struct address_space *mapping;
2401 	pte_t new_pte;
2402 
2403 	/*
2404 	 * Currently, we are forced to kill the process in the event the
2405 	 * original mapper has unmapped pages from the child due to a failed
2406 	 * COW. Warn that such a situation has occured as it may not be obvious
2407 	 */
2408 	if (is_vma_resv_set(vma, HPAGE_RESV_UNMAPPED)) {
2409 		printk(KERN_WARNING
2410 			"PID %d killed due to inadequate hugepage pool\n",
2411 			current->pid);
2412 		return ret;
2413 	}
2414 
2415 	mapping = vma->vm_file->f_mapping;
2416 	idx = vma_hugecache_offset(h, vma, address);
2417 
2418 	/*
2419 	 * Use page lock to guard against racing truncation
2420 	 * before we get page_table_lock.
2421 	 */
2422 retry:
2423 	page = find_lock_page(mapping, idx);
2424 	if (!page) {
2425 		size = i_size_read(mapping->host) >> huge_page_shift(h);
2426 		if (idx >= size)
2427 			goto out;
2428 		page = alloc_huge_page(vma, address, 0);
2429 		if (IS_ERR(page)) {
2430 			ret = -PTR_ERR(page);
2431 			goto out;
2432 		}
2433 		clear_huge_page(page, address, huge_page_size(h));
2434 		__SetPageUptodate(page);
2435 
2436 		if (vma->vm_flags & VM_MAYSHARE) {
2437 			int err;
2438 			struct inode *inode = mapping->host;
2439 
2440 			err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
2441 			if (err) {
2442 				put_page(page);
2443 				if (err == -EEXIST)
2444 					goto retry;
2445 				goto out;
2446 			}
2447 
2448 			spin_lock(&inode->i_lock);
2449 			inode->i_blocks += blocks_per_huge_page(h);
2450 			spin_unlock(&inode->i_lock);
2451 		} else
2452 			lock_page(page);
2453 	}
2454 
2455 	/*
2456 	 * If we are going to COW a private mapping later, we examine the
2457 	 * pending reservations for this page now. This will ensure that
2458 	 * any allocations necessary to record that reservation occur outside
2459 	 * the spinlock.
2460 	 */
2461 	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
2462 		if (vma_needs_reservation(h, vma, address) < 0) {
2463 			ret = VM_FAULT_OOM;
2464 			goto backout_unlocked;
2465 		}
2466 
2467 	spin_lock(&mm->page_table_lock);
2468 	size = i_size_read(mapping->host) >> huge_page_shift(h);
2469 	if (idx >= size)
2470 		goto backout;
2471 
2472 	ret = 0;
2473 	if (!huge_pte_none(huge_ptep_get(ptep)))
2474 		goto backout;
2475 
2476 	new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
2477 				&& (vma->vm_flags & VM_SHARED)));
2478 	set_huge_pte_at(mm, address, ptep, new_pte);
2479 
2480 	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
2481 		/* Optimization, do the COW without a second fault */
2482 		ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page);
2483 	}
2484 
2485 	spin_unlock(&mm->page_table_lock);
2486 	unlock_page(page);
2487 out:
2488 	return ret;
2489 
2490 backout:
2491 	spin_unlock(&mm->page_table_lock);
2492 backout_unlocked:
2493 	unlock_page(page);
2494 	put_page(page);
2495 	goto out;
2496 }
2497 
2498 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2499 			unsigned long address, unsigned int flags)
2500 {
2501 	pte_t *ptep;
2502 	pte_t entry;
2503 	int ret;
2504 	struct page *pagecache_page = NULL;
2505 	static DEFINE_MUTEX(hugetlb_instantiation_mutex);
2506 	struct hstate *h = hstate_vma(vma);
2507 
2508 	ptep = huge_pte_alloc(mm, address, huge_page_size(h));
2509 	if (!ptep)
2510 		return VM_FAULT_OOM;
2511 
2512 	/*
2513 	 * Serialize hugepage allocation and instantiation, so that we don't
2514 	 * get spurious allocation failures if two CPUs race to instantiate
2515 	 * the same page in the page cache.
2516 	 */
2517 	mutex_lock(&hugetlb_instantiation_mutex);
2518 	entry = huge_ptep_get(ptep);
2519 	if (huge_pte_none(entry)) {
2520 		ret = hugetlb_no_page(mm, vma, address, ptep, flags);
2521 		goto out_mutex;
2522 	}
2523 
2524 	ret = 0;
2525 
2526 	/*
2527 	 * If we are going to COW the mapping later, we examine the pending
2528 	 * reservations for this page now. This will ensure that any
2529 	 * allocations necessary to record that reservation occur outside the
2530 	 * spinlock. For private mappings, we also lookup the pagecache
2531 	 * page now as it is used to determine if a reservation has been
2532 	 * consumed.
2533 	 */
2534 	if ((flags & FAULT_FLAG_WRITE) && !pte_write(entry)) {
2535 		if (vma_needs_reservation(h, vma, address) < 0) {
2536 			ret = VM_FAULT_OOM;
2537 			goto out_mutex;
2538 		}
2539 
2540 		if (!(vma->vm_flags & VM_MAYSHARE))
2541 			pagecache_page = hugetlbfs_pagecache_page(h,
2542 								vma, address);
2543 	}
2544 
2545 	spin_lock(&mm->page_table_lock);
2546 	/* Check for a racing update before calling hugetlb_cow */
2547 	if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
2548 		goto out_page_table_lock;
2549 
2550 
2551 	if (flags & FAULT_FLAG_WRITE) {
2552 		if (!pte_write(entry)) {
2553 			ret = hugetlb_cow(mm, vma, address, ptep, entry,
2554 							pagecache_page);
2555 			goto out_page_table_lock;
2556 		}
2557 		entry = pte_mkdirty(entry);
2558 	}
2559 	entry = pte_mkyoung(entry);
2560 	if (huge_ptep_set_access_flags(vma, address, ptep, entry,
2561 						flags & FAULT_FLAG_WRITE))
2562 		update_mmu_cache(vma, address, entry);
2563 
2564 out_page_table_lock:
2565 	spin_unlock(&mm->page_table_lock);
2566 
2567 	if (pagecache_page) {
2568 		unlock_page(pagecache_page);
2569 		put_page(pagecache_page);
2570 	}
2571 
2572 out_mutex:
2573 	mutex_unlock(&hugetlb_instantiation_mutex);
2574 
2575 	return ret;
2576 }
2577 
2578 /* Can be overriden by architectures */
2579 __attribute__((weak)) struct page *
2580 follow_huge_pud(struct mm_struct *mm, unsigned long address,
2581 	       pud_t *pud, int write)
2582 {
2583 	BUG();
2584 	return NULL;
2585 }
2586 
2587 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
2588 			struct page **pages, struct vm_area_struct **vmas,
2589 			unsigned long *position, int *length, int i,
2590 			unsigned int flags)
2591 {
2592 	unsigned long pfn_offset;
2593 	unsigned long vaddr = *position;
2594 	int remainder = *length;
2595 	struct hstate *h = hstate_vma(vma);
2596 
2597 	spin_lock(&mm->page_table_lock);
2598 	while (vaddr < vma->vm_end && remainder) {
2599 		pte_t *pte;
2600 		int absent;
2601 		struct page *page;
2602 
2603 		/*
2604 		 * Some archs (sparc64, sh*) have multiple pte_ts to
2605 		 * each hugepage.  We have to make sure we get the
2606 		 * first, for the page indexing below to work.
2607 		 */
2608 		pte = huge_pte_offset(mm, vaddr & huge_page_mask(h));
2609 		absent = !pte || huge_pte_none(huge_ptep_get(pte));
2610 
2611 		/*
2612 		 * When coredumping, it suits get_dump_page if we just return
2613 		 * an error where there's an empty slot with no huge pagecache
2614 		 * to back it.  This way, we avoid allocating a hugepage, and
2615 		 * the sparse dumpfile avoids allocating disk blocks, but its
2616 		 * huge holes still show up with zeroes where they need to be.
2617 		 */
2618 		if (absent && (flags & FOLL_DUMP) &&
2619 		    !hugetlbfs_pagecache_present(h, vma, vaddr)) {
2620 			remainder = 0;
2621 			break;
2622 		}
2623 
2624 		if (absent ||
2625 		    ((flags & FOLL_WRITE) && !pte_write(huge_ptep_get(pte)))) {
2626 			int ret;
2627 
2628 			spin_unlock(&mm->page_table_lock);
2629 			ret = hugetlb_fault(mm, vma, vaddr,
2630 				(flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
2631 			spin_lock(&mm->page_table_lock);
2632 			if (!(ret & VM_FAULT_ERROR))
2633 				continue;
2634 
2635 			remainder = 0;
2636 			break;
2637 		}
2638 
2639 		pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
2640 		page = pte_page(huge_ptep_get(pte));
2641 same_page:
2642 		if (pages) {
2643 			pages[i] = mem_map_offset(page, pfn_offset);
2644 			get_page(pages[i]);
2645 		}
2646 
2647 		if (vmas)
2648 			vmas[i] = vma;
2649 
2650 		vaddr += PAGE_SIZE;
2651 		++pfn_offset;
2652 		--remainder;
2653 		++i;
2654 		if (vaddr < vma->vm_end && remainder &&
2655 				pfn_offset < pages_per_huge_page(h)) {
2656 			/*
2657 			 * We use pfn_offset to avoid touching the pageframes
2658 			 * of this compound page.
2659 			 */
2660 			goto same_page;
2661 		}
2662 	}
2663 	spin_unlock(&mm->page_table_lock);
2664 	*length = remainder;
2665 	*position = vaddr;
2666 
2667 	return i ? i : -EFAULT;
2668 }
2669 
2670 void hugetlb_change_protection(struct vm_area_struct *vma,
2671 		unsigned long address, unsigned long end, pgprot_t newprot)
2672 {
2673 	struct mm_struct *mm = vma->vm_mm;
2674 	unsigned long start = address;
2675 	pte_t *ptep;
2676 	pte_t pte;
2677 	struct hstate *h = hstate_vma(vma);
2678 
2679 	BUG_ON(address >= end);
2680 	flush_cache_range(vma, address, end);
2681 
2682 	spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
2683 	spin_lock(&mm->page_table_lock);
2684 	for (; address < end; address += huge_page_size(h)) {
2685 		ptep = huge_pte_offset(mm, address);
2686 		if (!ptep)
2687 			continue;
2688 		if (huge_pmd_unshare(mm, &address, ptep))
2689 			continue;
2690 		if (!huge_pte_none(huge_ptep_get(ptep))) {
2691 			pte = huge_ptep_get_and_clear(mm, address, ptep);
2692 			pte = pte_mkhuge(pte_modify(pte, newprot));
2693 			set_huge_pte_at(mm, address, ptep, pte);
2694 		}
2695 	}
2696 	spin_unlock(&mm->page_table_lock);
2697 	spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
2698 
2699 	flush_tlb_range(vma, start, end);
2700 }
2701 
2702 int hugetlb_reserve_pages(struct inode *inode,
2703 					long from, long to,
2704 					struct vm_area_struct *vma,
2705 					int acctflag)
2706 {
2707 	long ret, chg;
2708 	struct hstate *h = hstate_inode(inode);
2709 
2710 	/*
2711 	 * Only apply hugepage reservation if asked. At fault time, an
2712 	 * attempt will be made for VM_NORESERVE to allocate a page
2713 	 * and filesystem quota without using reserves
2714 	 */
2715 	if (acctflag & VM_NORESERVE)
2716 		return 0;
2717 
2718 	/*
2719 	 * Shared mappings base their reservation on the number of pages that
2720 	 * are already allocated on behalf of the file. Private mappings need
2721 	 * to reserve the full area even if read-only as mprotect() may be
2722 	 * called to make the mapping read-write. Assume !vma is a shm mapping
2723 	 */
2724 	if (!vma || vma->vm_flags & VM_MAYSHARE)
2725 		chg = region_chg(&inode->i_mapping->private_list, from, to);
2726 	else {
2727 		struct resv_map *resv_map = resv_map_alloc();
2728 		if (!resv_map)
2729 			return -ENOMEM;
2730 
2731 		chg = to - from;
2732 
2733 		set_vma_resv_map(vma, resv_map);
2734 		set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
2735 	}
2736 
2737 	if (chg < 0)
2738 		return chg;
2739 
2740 	/* There must be enough filesystem quota for the mapping */
2741 	if (hugetlb_get_quota(inode->i_mapping, chg))
2742 		return -ENOSPC;
2743 
2744 	/*
2745 	 * Check enough hugepages are available for the reservation.
2746 	 * Hand back the quota if there are not
2747 	 */
2748 	ret = hugetlb_acct_memory(h, chg);
2749 	if (ret < 0) {
2750 		hugetlb_put_quota(inode->i_mapping, chg);
2751 		return ret;
2752 	}
2753 
2754 	/*
2755 	 * Account for the reservations made. Shared mappings record regions
2756 	 * that have reservations as they are shared by multiple VMAs.
2757 	 * When the last VMA disappears, the region map says how much
2758 	 * the reservation was and the page cache tells how much of
2759 	 * the reservation was consumed. Private mappings are per-VMA and
2760 	 * only the consumed reservations are tracked. When the VMA
2761 	 * disappears, the original reservation is the VMA size and the
2762 	 * consumed reservations are stored in the map. Hence, nothing
2763 	 * else has to be done for private mappings here
2764 	 */
2765 	if (!vma || vma->vm_flags & VM_MAYSHARE)
2766 		region_add(&inode->i_mapping->private_list, from, to);
2767 	return 0;
2768 }
2769 
2770 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
2771 {
2772 	struct hstate *h = hstate_inode(inode);
2773 	long chg = region_truncate(&inode->i_mapping->private_list, offset);
2774 
2775 	spin_lock(&inode->i_lock);
2776 	inode->i_blocks -= (blocks_per_huge_page(h) * freed);
2777 	spin_unlock(&inode->i_lock);
2778 
2779 	hugetlb_put_quota(inode->i_mapping, (chg - freed));
2780 	hugetlb_acct_memory(h, -(chg - freed));
2781 }
2782