ia64/linux-2.6.18-xen.hg

view mm/hugetlb.c @ 563:3b3701ad4eec

pvSCSI frontend driver

Signed-off-by: Tomonari Horikoshi <t.horikoshi@jp.fujitsu.com>
Signed-off-by: Jun Kamada <kama@jp.fujitsu.com>
author Keir Fraser <keir.fraser@citrix.com>
date Mon Jun 02 09:58:56 2008 +0100 (2008-06-02)
parents 831230e53067
children
line source
1 /*
2 * Generic hugetlb support.
3 * (C) William Irwin, April 2004
4 */
5 #include <linux/gfp.h>
6 #include <linux/list.h>
7 #include <linux/init.h>
8 #include <linux/module.h>
9 #include <linux/mm.h>
10 #include <linux/sysctl.h>
11 #include <linux/highmem.h>
12 #include <linux/nodemask.h>
13 #include <linux/pagemap.h>
14 #include <linux/mempolicy.h>
15 #include <linux/cpuset.h>
16 #include <linux/mutex.h>
18 #include <asm/page.h>
19 #include <asm/pgtable.h>
21 #include <linux/hugetlb.h>
22 #include "internal.h"
24 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
25 static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;
26 unsigned long max_huge_pages;
27 static struct list_head hugepage_freelists[MAX_NUMNODES];
28 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
29 static unsigned int free_huge_pages_node[MAX_NUMNODES];
30 /*
31 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
32 */
33 static DEFINE_SPINLOCK(hugetlb_lock);
35 static void clear_huge_page(struct page *page, unsigned long addr)
36 {
37 int i;
39 might_sleep();
40 for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
41 cond_resched();
42 clear_user_highpage(page + i, addr);
43 }
44 }
46 static void copy_huge_page(struct page *dst, struct page *src,
47 unsigned long addr)
48 {
49 int i;
51 might_sleep();
52 for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
53 cond_resched();
54 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE);
55 }
56 }
58 static void enqueue_huge_page(struct page *page)
59 {
60 int nid = page_to_nid(page);
61 list_add(&page->lru, &hugepage_freelists[nid]);
62 free_huge_pages++;
63 free_huge_pages_node[nid]++;
64 }
66 static struct page *dequeue_huge_page(struct vm_area_struct *vma,
67 unsigned long address)
68 {
69 int nid = numa_node_id();
70 struct page *page = NULL;
71 struct zonelist *zonelist = huge_zonelist(vma, address);
72 struct zone **z;
74 for (z = zonelist->zones; *z; z++) {
75 nid = (*z)->zone_pgdat->node_id;
76 if (cpuset_zone_allowed(*z, GFP_HIGHUSER) &&
77 !list_empty(&hugepage_freelists[nid]))
78 break;
79 }
81 if (*z) {
82 page = list_entry(hugepage_freelists[nid].next,
83 struct page, lru);
84 list_del(&page->lru);
85 free_huge_pages--;
86 free_huge_pages_node[nid]--;
87 }
88 return page;
89 }
91 static void free_huge_page(struct page *page)
92 {
93 BUG_ON(page_count(page));
95 INIT_LIST_HEAD(&page->lru);
97 spin_lock(&hugetlb_lock);
98 enqueue_huge_page(page);
99 spin_unlock(&hugetlb_lock);
100 }
102 static int alloc_fresh_huge_page(void)
103 {
104 static int nid = 0;
105 struct page *page;
106 page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
107 HUGETLB_PAGE_ORDER);
108 nid = next_node(nid, node_online_map);
109 if (nid == MAX_NUMNODES)
110 nid = first_node(node_online_map);
111 if (page) {
112 page[1].lru.next = (void *)free_huge_page; /* dtor */
113 spin_lock(&hugetlb_lock);
114 nr_huge_pages++;
115 nr_huge_pages_node[page_to_nid(page)]++;
116 spin_unlock(&hugetlb_lock);
117 put_page(page); /* free it into the hugepage allocator */
118 return 1;
119 }
120 return 0;
121 }
123 static struct page *alloc_huge_page(struct vm_area_struct *vma,
124 unsigned long addr)
125 {
126 struct page *page;
128 spin_lock(&hugetlb_lock);
129 if (vma->vm_flags & VM_MAYSHARE)
130 resv_huge_pages--;
131 else if (free_huge_pages <= resv_huge_pages)
132 goto fail;
134 page = dequeue_huge_page(vma, addr);
135 if (!page)
136 goto fail;
138 spin_unlock(&hugetlb_lock);
139 set_page_refcounted(page);
140 return page;
142 fail:
143 spin_unlock(&hugetlb_lock);
144 return NULL;
145 }
147 static int __init hugetlb_init(void)
148 {
149 unsigned long i;
151 if (HPAGE_SHIFT == 0)
152 return 0;
154 for (i = 0; i < MAX_NUMNODES; ++i)
155 INIT_LIST_HEAD(&hugepage_freelists[i]);
157 for (i = 0; i < max_huge_pages; ++i) {
158 if (!alloc_fresh_huge_page())
159 break;
160 }
161 max_huge_pages = free_huge_pages = nr_huge_pages = i;
162 printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
163 return 0;
164 }
165 module_init(hugetlb_init);
167 static int __init hugetlb_setup(char *s)
168 {
169 if (sscanf(s, "%lu", &max_huge_pages) <= 0)
170 max_huge_pages = 0;
171 return 1;
172 }
173 __setup("hugepages=", hugetlb_setup);
175 #ifdef CONFIG_SYSCTL
176 static void update_and_free_page(struct page *page)
177 {
178 int i;
179 nr_huge_pages--;
180 nr_huge_pages_node[page_zone(page)->zone_pgdat->node_id]--;
181 for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
182 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
183 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
184 1 << PG_private | 1<< PG_writeback);
185 }
186 page[1].lru.next = NULL;
187 set_page_refcounted(page);
188 __free_pages(page, HUGETLB_PAGE_ORDER);
189 }
191 #ifdef CONFIG_HIGHMEM
192 static void try_to_free_low(unsigned long count)
193 {
194 int i, nid;
195 for (i = 0; i < MAX_NUMNODES; ++i) {
196 struct page *page, *next;
197 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
198 if (PageHighMem(page))
199 continue;
200 list_del(&page->lru);
201 update_and_free_page(page);
202 nid = page_zone(page)->zone_pgdat->node_id;
203 free_huge_pages--;
204 free_huge_pages_node[nid]--;
205 if (count >= nr_huge_pages)
206 return;
207 }
208 }
209 }
210 #else
211 static inline void try_to_free_low(unsigned long count)
212 {
213 }
214 #endif
216 static unsigned long set_max_huge_pages(unsigned long count)
217 {
218 while (count > nr_huge_pages) {
219 if (!alloc_fresh_huge_page())
220 return nr_huge_pages;
221 }
222 if (count >= nr_huge_pages)
223 return nr_huge_pages;
225 spin_lock(&hugetlb_lock);
226 count = max(count, resv_huge_pages);
227 try_to_free_low(count);
228 while (count < nr_huge_pages) {
229 struct page *page = dequeue_huge_page(NULL, 0);
230 if (!page)
231 break;
232 update_and_free_page(page);
233 }
234 spin_unlock(&hugetlb_lock);
235 return nr_huge_pages;
236 }
238 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
239 struct file *file, void __user *buffer,
240 size_t *length, loff_t *ppos)
241 {
242 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
243 max_huge_pages = set_max_huge_pages(max_huge_pages);
244 return 0;
245 }
246 #endif /* CONFIG_SYSCTL */
248 int hugetlb_report_meminfo(char *buf)
249 {
250 return sprintf(buf,
251 "HugePages_Total: %5lu\n"
252 "HugePages_Free: %5lu\n"
253 "HugePages_Rsvd: %5lu\n"
254 "Hugepagesize: %5lu kB\n",
255 nr_huge_pages,
256 free_huge_pages,
257 resv_huge_pages,
258 HPAGE_SIZE/1024);
259 }
261 int hugetlb_report_node_meminfo(int nid, char *buf)
262 {
263 return sprintf(buf,
264 "Node %d HugePages_Total: %5u\n"
265 "Node %d HugePages_Free: %5u\n",
266 nid, nr_huge_pages_node[nid],
267 nid, free_huge_pages_node[nid]);
268 }
270 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
271 unsigned long hugetlb_total_pages(void)
272 {
273 return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
274 }
276 /*
277 * We cannot handle pagefaults against hugetlb pages at all. They cause
278 * handle_mm_fault() to try to instantiate regular-sized pages in the
279 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
280 * this far.
281 */
282 static struct page *hugetlb_nopage(struct vm_area_struct *vma,
283 unsigned long address, int *unused)
284 {
285 BUG();
286 return NULL;
287 }
289 struct vm_operations_struct hugetlb_vm_ops = {
290 .nopage = hugetlb_nopage,
291 };
293 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
294 int writable)
295 {
296 pte_t entry;
298 if (writable) {
299 entry =
300 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
301 } else {
302 entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
303 }
304 entry = pte_mkyoung(entry);
305 entry = pte_mkhuge(entry);
307 return entry;
308 }
310 static void set_huge_ptep_writable(struct vm_area_struct *vma,
311 unsigned long address, pte_t *ptep)
312 {
313 pte_t entry;
315 entry = pte_mkwrite(pte_mkdirty(*ptep));
316 ptep_set_access_flags(vma, address, ptep, entry, 1);
317 update_mmu_cache(vma, address, entry);
318 lazy_mmu_prot_update(entry);
319 }
322 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
323 struct vm_area_struct *vma)
324 {
325 pte_t *src_pte, *dst_pte, entry;
326 struct page *ptepage;
327 unsigned long addr;
328 int cow;
330 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
332 for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
333 src_pte = huge_pte_offset(src, addr);
334 if (!src_pte)
335 continue;
336 dst_pte = huge_pte_alloc(dst, addr);
337 if (!dst_pte)
338 goto nomem;
339 spin_lock(&dst->page_table_lock);
340 spin_lock(&src->page_table_lock);
341 if (!pte_none(*src_pte)) {
342 if (cow)
343 ptep_set_wrprotect(src, addr, src_pte);
344 entry = *src_pte;
345 ptepage = pte_page(entry);
346 get_page(ptepage);
347 add_mm_counter(dst, file_rss, HPAGE_SIZE / PAGE_SIZE);
348 set_huge_pte_at(dst, addr, dst_pte, entry);
349 }
350 spin_unlock(&src->page_table_lock);
351 spin_unlock(&dst->page_table_lock);
352 }
353 return 0;
355 nomem:
356 return -ENOMEM;
357 }
359 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
360 unsigned long end)
361 {
362 struct mm_struct *mm = vma->vm_mm;
363 unsigned long address;
364 pte_t *ptep;
365 pte_t pte;
366 struct page *page;
368 WARN_ON(!is_vm_hugetlb_page(vma));
369 BUG_ON(start & ~HPAGE_MASK);
370 BUG_ON(end & ~HPAGE_MASK);
372 spin_lock(&mm->page_table_lock);
374 /* Update high watermark before we lower rss */
375 update_hiwater_rss(mm);
377 for (address = start; address < end; address += HPAGE_SIZE) {
378 ptep = huge_pte_offset(mm, address);
379 if (!ptep)
380 continue;
382 pte = huge_ptep_get_and_clear(mm, address, ptep);
383 if (pte_none(pte))
384 continue;
386 page = pte_page(pte);
387 put_page(page);
388 add_mm_counter(mm, file_rss, (int) -(HPAGE_SIZE / PAGE_SIZE));
389 }
391 spin_unlock(&mm->page_table_lock);
392 flush_tlb_range(vma, start, end);
393 }
395 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
396 unsigned long address, pte_t *ptep, pte_t pte)
397 {
398 struct page *old_page, *new_page;
399 int avoidcopy;
401 old_page = pte_page(pte);
403 /* If no-one else is actually using this page, avoid the copy
404 * and just make the page writable */
405 avoidcopy = (page_count(old_page) == 1);
406 if (avoidcopy) {
407 set_huge_ptep_writable(vma, address, ptep);
408 return VM_FAULT_MINOR;
409 }
411 page_cache_get(old_page);
412 new_page = alloc_huge_page(vma, address);
414 if (!new_page) {
415 page_cache_release(old_page);
416 return VM_FAULT_OOM;
417 }
419 spin_unlock(&mm->page_table_lock);
420 copy_huge_page(new_page, old_page, address);
421 spin_lock(&mm->page_table_lock);
423 ptep = huge_pte_offset(mm, address & HPAGE_MASK);
424 if (likely(pte_same(*ptep, pte))) {
425 /* Break COW */
426 set_huge_pte_at(mm, address, ptep,
427 make_huge_pte(vma, new_page, 1));
428 /* Make the old page be freed below */
429 new_page = old_page;
430 }
431 page_cache_release(new_page);
432 page_cache_release(old_page);
433 return VM_FAULT_MINOR;
434 }
436 int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
437 unsigned long address, pte_t *ptep, int write_access)
438 {
439 int ret = VM_FAULT_SIGBUS;
440 unsigned long idx;
441 unsigned long size;
442 struct page *page;
443 struct address_space *mapping;
444 pte_t new_pte;
446 mapping = vma->vm_file->f_mapping;
447 idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
448 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
450 /*
451 * Use page lock to guard against racing truncation
452 * before we get page_table_lock.
453 */
454 retry:
455 page = find_lock_page(mapping, idx);
456 if (!page) {
457 if (hugetlb_get_quota(mapping))
458 goto out;
459 page = alloc_huge_page(vma, address);
460 if (!page) {
461 hugetlb_put_quota(mapping);
462 ret = VM_FAULT_OOM;
463 goto out;
464 }
465 clear_huge_page(page, address);
467 if (vma->vm_flags & VM_SHARED) {
468 int err;
470 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
471 if (err) {
472 put_page(page);
473 hugetlb_put_quota(mapping);
474 if (err == -EEXIST)
475 goto retry;
476 goto out;
477 }
478 } else
479 lock_page(page);
480 }
482 spin_lock(&mm->page_table_lock);
483 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
484 if (idx >= size)
485 goto backout;
487 ret = VM_FAULT_MINOR;
488 if (!pte_none(*ptep))
489 goto backout;
491 add_mm_counter(mm, file_rss, HPAGE_SIZE / PAGE_SIZE);
492 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
493 && (vma->vm_flags & VM_SHARED)));
494 set_huge_pte_at(mm, address, ptep, new_pte);
496 if (write_access && !(vma->vm_flags & VM_SHARED)) {
497 /* Optimization, do the COW without a second fault */
498 ret = hugetlb_cow(mm, vma, address, ptep, new_pte);
499 }
501 spin_unlock(&mm->page_table_lock);
502 unlock_page(page);
503 out:
504 return ret;
506 backout:
507 spin_unlock(&mm->page_table_lock);
508 hugetlb_put_quota(mapping);
509 unlock_page(page);
510 put_page(page);
511 goto out;
512 }
514 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
515 unsigned long address, int write_access)
516 {
517 pte_t *ptep;
518 pte_t entry;
519 int ret;
520 static DEFINE_MUTEX(hugetlb_instantiation_mutex);
522 ptep = huge_pte_alloc(mm, address);
523 if (!ptep)
524 return VM_FAULT_OOM;
526 /*
527 * Serialize hugepage allocation and instantiation, so that we don't
528 * get spurious allocation failures if two CPUs race to instantiate
529 * the same page in the page cache.
530 */
531 mutex_lock(&hugetlb_instantiation_mutex);
532 entry = *ptep;
533 if (pte_none(entry)) {
534 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
535 mutex_unlock(&hugetlb_instantiation_mutex);
536 return ret;
537 }
539 ret = VM_FAULT_MINOR;
541 spin_lock(&mm->page_table_lock);
542 /* Check for a racing update before calling hugetlb_cow */
543 if (likely(pte_same(entry, *ptep)))
544 if (write_access && !pte_write(entry))
545 ret = hugetlb_cow(mm, vma, address, ptep, entry);
546 spin_unlock(&mm->page_table_lock);
547 mutex_unlock(&hugetlb_instantiation_mutex);
549 return ret;
550 }
552 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
553 struct page **pages, struct vm_area_struct **vmas,
554 unsigned long *position, int *length, int i)
555 {
556 unsigned long pfn_offset;
557 unsigned long vaddr = *position;
558 int remainder = *length;
560 spin_lock(&mm->page_table_lock);
561 while (vaddr < vma->vm_end && remainder) {
562 pte_t *pte;
563 struct page *page;
565 /*
566 * Some archs (sparc64, sh*) have multiple pte_ts to
567 * each hugepage. We have to make * sure we get the
568 * first, for the page indexing below to work.
569 */
570 pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
572 if (!pte || pte_none(*pte)) {
573 int ret;
575 spin_unlock(&mm->page_table_lock);
576 ret = hugetlb_fault(mm, vma, vaddr, 0);
577 spin_lock(&mm->page_table_lock);
578 if (ret == VM_FAULT_MINOR)
579 continue;
581 remainder = 0;
582 if (!i)
583 i = -EFAULT;
584 break;
585 }
587 pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
588 page = pte_page(*pte);
589 same_page:
590 if (pages) {
591 get_page(page);
592 pages[i] = page + pfn_offset;
593 }
595 if (vmas)
596 vmas[i] = vma;
598 vaddr += PAGE_SIZE;
599 ++pfn_offset;
600 --remainder;
601 ++i;
602 if (vaddr < vma->vm_end && remainder &&
603 pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
604 /*
605 * We use pfn_offset to avoid touching the pageframes
606 * of this compound page.
607 */
608 goto same_page;
609 }
610 }
611 spin_unlock(&mm->page_table_lock);
612 *length = remainder;
613 *position = vaddr;
615 return i;
616 }
618 void hugetlb_change_protection(struct vm_area_struct *vma,
619 unsigned long address, unsigned long end, pgprot_t newprot)
620 {
621 struct mm_struct *mm = vma->vm_mm;
622 unsigned long start = address;
623 pte_t *ptep;
624 pte_t pte;
626 BUG_ON(address >= end);
627 flush_cache_range(vma, address, end);
629 spin_lock(&mm->page_table_lock);
630 for (; address < end; address += HPAGE_SIZE) {
631 ptep = huge_pte_offset(mm, address);
632 if (!ptep)
633 continue;
634 if (!pte_none(*ptep)) {
635 pte = huge_ptep_get_and_clear(mm, address, ptep);
636 pte = pte_mkhuge(pte_modify(pte, newprot));
637 set_huge_pte_at(mm, address, ptep, pte);
638 lazy_mmu_prot_update(pte);
639 }
640 }
641 spin_unlock(&mm->page_table_lock);
643 flush_tlb_range(vma, start, end);
644 }
646 struct file_region {
647 struct list_head link;
648 long from;
649 long to;
650 };
652 static long region_add(struct list_head *head, long f, long t)
653 {
654 struct file_region *rg, *nrg, *trg;
656 /* Locate the region we are either in or before. */
657 list_for_each_entry(rg, head, link)
658 if (f <= rg->to)
659 break;
661 /* Round our left edge to the current segment if it encloses us. */
662 if (f > rg->from)
663 f = rg->from;
665 /* Check for and consume any regions we now overlap with. */
666 nrg = rg;
667 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
668 if (&rg->link == head)
669 break;
670 if (rg->from > t)
671 break;
673 /* If this area reaches higher then extend our area to
674 * include it completely. If this is not the first area
675 * which we intend to reuse, free it. */
676 if (rg->to > t)
677 t = rg->to;
678 if (rg != nrg) {
679 list_del(&rg->link);
680 kfree(rg);
681 }
682 }
683 nrg->from = f;
684 nrg->to = t;
685 return 0;
686 }
688 static long region_chg(struct list_head *head, long f, long t)
689 {
690 struct file_region *rg, *nrg;
691 long chg = 0;
693 /* Locate the region we are before or in. */
694 list_for_each_entry(rg, head, link)
695 if (f <= rg->to)
696 break;
698 /* If we are below the current region then a new region is required.
699 * Subtle, allocate a new region at the position but make it zero
700 * size such that we can guarentee to record the reservation. */
701 if (&rg->link == head || t < rg->from) {
702 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
703 if (nrg == 0)
704 return -ENOMEM;
705 nrg->from = f;
706 nrg->to = f;
707 INIT_LIST_HEAD(&nrg->link);
708 list_add(&nrg->link, rg->link.prev);
710 return t - f;
711 }
713 /* Round our left edge to the current segment if it encloses us. */
714 if (f > rg->from)
715 f = rg->from;
716 chg = t - f;
718 /* Check for and consume any regions we now overlap with. */
719 list_for_each_entry(rg, rg->link.prev, link) {
720 if (&rg->link == head)
721 break;
722 if (rg->from > t)
723 return chg;
725 /* We overlap with this area, if it extends futher than
726 * us then we must extend ourselves. Account for its
727 * existing reservation. */
728 if (rg->to > t) {
729 chg += rg->to - t;
730 t = rg->to;
731 }
732 chg -= rg->to - rg->from;
733 }
734 return chg;
735 }
737 static long region_truncate(struct list_head *head, long end)
738 {
739 struct file_region *rg, *trg;
740 long chg = 0;
742 /* Locate the region we are either in or before. */
743 list_for_each_entry(rg, head, link)
744 if (end <= rg->to)
745 break;
746 if (&rg->link == head)
747 return 0;
749 /* If we are in the middle of a region then adjust it. */
750 if (end > rg->from) {
751 chg = rg->to - end;
752 rg->to = end;
753 rg = list_entry(rg->link.next, typeof(*rg), link);
754 }
756 /* Drop any remaining regions. */
757 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
758 if (&rg->link == head)
759 break;
760 chg += rg->to - rg->from;
761 list_del(&rg->link);
762 kfree(rg);
763 }
764 return chg;
765 }
767 static int hugetlb_acct_memory(long delta)
768 {
769 int ret = -ENOMEM;
771 spin_lock(&hugetlb_lock);
772 if ((delta + resv_huge_pages) <= free_huge_pages) {
773 resv_huge_pages += delta;
774 ret = 0;
775 }
776 spin_unlock(&hugetlb_lock);
777 return ret;
778 }
780 int hugetlb_reserve_pages(struct inode *inode, long from, long to)
781 {
782 long ret, chg;
784 chg = region_chg(&inode->i_mapping->private_list, from, to);
785 if (chg < 0)
786 return chg;
787 ret = hugetlb_acct_memory(chg);
788 if (ret < 0)
789 return ret;
790 region_add(&inode->i_mapping->private_list, from, to);
791 return 0;
792 }
794 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
795 {
796 long chg = region_truncate(&inode->i_mapping->private_list, offset);
797 hugetlb_acct_memory(freed - chg);
798 }