b43/nphy.c: include headers to avoid build breakage on some platforms
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / mm / hugetlb.c
blobdb861d8b6c2824f460cc177f0d4008fd8850cc3e
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 static unsigned long surplus_huge_pages;
27 unsigned long max_huge_pages;
28 static struct list_head hugepage_freelists[MAX_NUMNODES];
29 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
30 static unsigned int free_huge_pages_node[MAX_NUMNODES];
31 static unsigned int surplus_huge_pages_node[MAX_NUMNODES];
32 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
33 unsigned long hugepages_treat_as_movable;
34 unsigned long nr_overcommit_huge_pages;
35 static int hugetlb_next_nid;
38 * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
40 static DEFINE_SPINLOCK(hugetlb_lock);
42 static void clear_huge_page(struct page *page, unsigned long addr)
44 int i;
46 might_sleep();
47 for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
48 cond_resched();
49 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
53 static void copy_huge_page(struct page *dst, struct page *src,
54 unsigned long addr, struct vm_area_struct *vma)
56 int i;
58 might_sleep();
59 for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
60 cond_resched();
61 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
65 static void enqueue_huge_page(struct page *page)
67 int nid = page_to_nid(page);
68 list_add(&page->lru, &hugepage_freelists[nid]);
69 free_huge_pages++;
70 free_huge_pages_node[nid]++;
73 static struct page *dequeue_huge_page(struct vm_area_struct *vma,
74 unsigned long address)
76 int nid;
77 struct page *page = NULL;
78 struct mempolicy *mpol;
79 struct zonelist *zonelist = huge_zonelist(vma, address,
80 htlb_alloc_mask, &mpol);
81 struct zone **z;
83 for (z = zonelist->zones; *z; z++) {
84 nid = zone_to_nid(*z);
85 if (cpuset_zone_allowed_softwall(*z, htlb_alloc_mask) &&
86 !list_empty(&hugepage_freelists[nid])) {
87 page = list_entry(hugepage_freelists[nid].next,
88 struct page, lru);
89 list_del(&page->lru);
90 free_huge_pages--;
91 free_huge_pages_node[nid]--;
92 if (vma && vma->vm_flags & VM_MAYSHARE)
93 resv_huge_pages--;
94 break;
97 mpol_free(mpol); /* unref if mpol !NULL */
98 return page;
101 static void update_and_free_page(struct page *page)
103 int i;
104 nr_huge_pages--;
105 nr_huge_pages_node[page_to_nid(page)]--;
106 for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
107 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
108 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
109 1 << PG_private | 1<< PG_writeback);
111 set_compound_page_dtor(page, NULL);
112 set_page_refcounted(page);
113 __free_pages(page, HUGETLB_PAGE_ORDER);
116 static void free_huge_page(struct page *page)
118 int nid = page_to_nid(page);
119 struct address_space *mapping;
121 mapping = (struct address_space *) page_private(page);
122 BUG_ON(page_count(page));
123 INIT_LIST_HEAD(&page->lru);
125 spin_lock(&hugetlb_lock);
126 if (surplus_huge_pages_node[nid]) {
127 update_and_free_page(page);
128 surplus_huge_pages--;
129 surplus_huge_pages_node[nid]--;
130 } else {
131 enqueue_huge_page(page);
133 spin_unlock(&hugetlb_lock);
134 if (mapping)
135 hugetlb_put_quota(mapping, 1);
136 set_page_private(page, 0);
140 * Increment or decrement surplus_huge_pages. Keep node-specific counters
141 * balanced by operating on them in a round-robin fashion.
142 * Returns 1 if an adjustment was made.
144 static int adjust_pool_surplus(int delta)
146 static int prev_nid;
147 int nid = prev_nid;
148 int ret = 0;
150 VM_BUG_ON(delta != -1 && delta != 1);
151 do {
152 nid = next_node(nid, node_online_map);
153 if (nid == MAX_NUMNODES)
154 nid = first_node(node_online_map);
156 /* To shrink on this node, there must be a surplus page */
157 if (delta < 0 && !surplus_huge_pages_node[nid])
158 continue;
159 /* Surplus cannot exceed the total number of pages */
160 if (delta > 0 && surplus_huge_pages_node[nid] >=
161 nr_huge_pages_node[nid])
162 continue;
164 surplus_huge_pages += delta;
165 surplus_huge_pages_node[nid] += delta;
166 ret = 1;
167 break;
168 } while (nid != prev_nid);
170 prev_nid = nid;
171 return ret;
174 static struct page *alloc_fresh_huge_page_node(int nid)
176 struct page *page;
178 page = alloc_pages_node(nid,
179 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|__GFP_NOWARN,
180 HUGETLB_PAGE_ORDER);
181 if (page) {
182 set_compound_page_dtor(page, free_huge_page);
183 spin_lock(&hugetlb_lock);
184 nr_huge_pages++;
185 nr_huge_pages_node[nid]++;
186 spin_unlock(&hugetlb_lock);
187 put_page(page); /* free it into the hugepage allocator */
190 return page;
193 static int alloc_fresh_huge_page(void)
195 struct page *page;
196 int start_nid;
197 int next_nid;
198 int ret = 0;
200 start_nid = hugetlb_next_nid;
202 do {
203 page = alloc_fresh_huge_page_node(hugetlb_next_nid);
204 if (page)
205 ret = 1;
207 * Use a helper variable to find the next node and then
208 * copy it back to hugetlb_next_nid afterwards:
209 * otherwise there's a window in which a racer might
210 * pass invalid nid MAX_NUMNODES to alloc_pages_node.
211 * But we don't need to use a spin_lock here: it really
212 * doesn't matter if occasionally a racer chooses the
213 * same nid as we do. Move nid forward in the mask even
214 * if we just successfully allocated a hugepage so that
215 * the next caller gets hugepages on the next node.
217 next_nid = next_node(hugetlb_next_nid, node_online_map);
218 if (next_nid == MAX_NUMNODES)
219 next_nid = first_node(node_online_map);
220 hugetlb_next_nid = next_nid;
221 } while (!page && hugetlb_next_nid != start_nid);
223 return ret;
226 static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma,
227 unsigned long address)
229 struct page *page;
230 unsigned int nid;
233 * Assume we will successfully allocate the surplus page to
234 * prevent racing processes from causing the surplus to exceed
235 * overcommit
237 * This however introduces a different race, where a process B
238 * tries to grow the static hugepage pool while alloc_pages() is
239 * called by process A. B will only examine the per-node
240 * counters in determining if surplus huge pages can be
241 * converted to normal huge pages in adjust_pool_surplus(). A
242 * won't be able to increment the per-node counter, until the
243 * lock is dropped by B, but B doesn't drop hugetlb_lock until
244 * no more huge pages can be converted from surplus to normal
245 * state (and doesn't try to convert again). Thus, we have a
246 * case where a surplus huge page exists, the pool is grown, and
247 * the surplus huge page still exists after, even though it
248 * should just have been converted to a normal huge page. This
249 * does not leak memory, though, as the hugepage will be freed
250 * once it is out of use. It also does not allow the counters to
251 * go out of whack in adjust_pool_surplus() as we don't modify
252 * the node values until we've gotten the hugepage and only the
253 * per-node value is checked there.
255 spin_lock(&hugetlb_lock);
256 if (surplus_huge_pages >= nr_overcommit_huge_pages) {
257 spin_unlock(&hugetlb_lock);
258 return NULL;
259 } else {
260 nr_huge_pages++;
261 surplus_huge_pages++;
263 spin_unlock(&hugetlb_lock);
265 page = alloc_pages(htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
266 HUGETLB_PAGE_ORDER);
268 spin_lock(&hugetlb_lock);
269 if (page) {
270 nid = page_to_nid(page);
271 set_compound_page_dtor(page, free_huge_page);
273 * We incremented the global counters already
275 nr_huge_pages_node[nid]++;
276 surplus_huge_pages_node[nid]++;
277 } else {
278 nr_huge_pages--;
279 surplus_huge_pages--;
281 spin_unlock(&hugetlb_lock);
283 return page;
287 * Increase the hugetlb pool such that it can accomodate a reservation
288 * of size 'delta'.
290 static int gather_surplus_pages(int delta)
292 struct list_head surplus_list;
293 struct page *page, *tmp;
294 int ret, i;
295 int needed, allocated;
297 needed = (resv_huge_pages + delta) - free_huge_pages;
298 if (needed <= 0)
299 return 0;
301 allocated = 0;
302 INIT_LIST_HEAD(&surplus_list);
304 ret = -ENOMEM;
305 retry:
306 spin_unlock(&hugetlb_lock);
307 for (i = 0; i < needed; i++) {
308 page = alloc_buddy_huge_page(NULL, 0);
309 if (!page) {
311 * We were not able to allocate enough pages to
312 * satisfy the entire reservation so we free what
313 * we've allocated so far.
315 spin_lock(&hugetlb_lock);
316 needed = 0;
317 goto free;
320 list_add(&page->lru, &surplus_list);
322 allocated += needed;
325 * After retaking hugetlb_lock, we need to recalculate 'needed'
326 * because either resv_huge_pages or free_huge_pages may have changed.
328 spin_lock(&hugetlb_lock);
329 needed = (resv_huge_pages + delta) - (free_huge_pages + allocated);
330 if (needed > 0)
331 goto retry;
334 * The surplus_list now contains _at_least_ the number of extra pages
335 * needed to accomodate the reservation. Add the appropriate number
336 * of pages to the hugetlb pool and free the extras back to the buddy
337 * allocator.
339 needed += allocated;
340 ret = 0;
341 free:
342 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
343 list_del(&page->lru);
344 if ((--needed) >= 0)
345 enqueue_huge_page(page);
346 else {
348 * Decrement the refcount and free the page using its
349 * destructor. This must be done with hugetlb_lock
350 * unlocked which is safe because free_huge_page takes
351 * hugetlb_lock before deciding how to free the page.
353 spin_unlock(&hugetlb_lock);
354 put_page(page);
355 spin_lock(&hugetlb_lock);
359 return ret;
363 * When releasing a hugetlb pool reservation, any surplus pages that were
364 * allocated to satisfy the reservation must be explicitly freed if they were
365 * never used.
367 static void return_unused_surplus_pages(unsigned long unused_resv_pages)
369 static int nid = -1;
370 struct page *page;
371 unsigned long nr_pages;
373 nr_pages = min(unused_resv_pages, surplus_huge_pages);
375 while (nr_pages) {
376 nid = next_node(nid, node_online_map);
377 if (nid == MAX_NUMNODES)
378 nid = first_node(node_online_map);
380 if (!surplus_huge_pages_node[nid])
381 continue;
383 if (!list_empty(&hugepage_freelists[nid])) {
384 page = list_entry(hugepage_freelists[nid].next,
385 struct page, lru);
386 list_del(&page->lru);
387 update_and_free_page(page);
388 free_huge_pages--;
389 free_huge_pages_node[nid]--;
390 surplus_huge_pages--;
391 surplus_huge_pages_node[nid]--;
392 nr_pages--;
398 static struct page *alloc_huge_page_shared(struct vm_area_struct *vma,
399 unsigned long addr)
401 struct page *page;
403 spin_lock(&hugetlb_lock);
404 page = dequeue_huge_page(vma, addr);
405 spin_unlock(&hugetlb_lock);
406 return page ? page : ERR_PTR(-VM_FAULT_OOM);
409 static struct page *alloc_huge_page_private(struct vm_area_struct *vma,
410 unsigned long addr)
412 struct page *page = NULL;
414 if (hugetlb_get_quota(vma->vm_file->f_mapping, 1))
415 return ERR_PTR(-VM_FAULT_SIGBUS);
417 spin_lock(&hugetlb_lock);
418 if (free_huge_pages > resv_huge_pages)
419 page = dequeue_huge_page(vma, addr);
420 spin_unlock(&hugetlb_lock);
421 if (!page) {
422 page = alloc_buddy_huge_page(vma, addr);
423 if (!page) {
424 hugetlb_put_quota(vma->vm_file->f_mapping, 1);
425 return ERR_PTR(-VM_FAULT_OOM);
428 return page;
431 static struct page *alloc_huge_page(struct vm_area_struct *vma,
432 unsigned long addr)
434 struct page *page;
435 struct address_space *mapping = vma->vm_file->f_mapping;
437 if (vma->vm_flags & VM_MAYSHARE)
438 page = alloc_huge_page_shared(vma, addr);
439 else
440 page = alloc_huge_page_private(vma, addr);
442 if (!IS_ERR(page)) {
443 set_page_refcounted(page);
444 set_page_private(page, (unsigned long) mapping);
446 return page;
449 static int __init hugetlb_init(void)
451 unsigned long i;
453 if (HPAGE_SHIFT == 0)
454 return 0;
456 for (i = 0; i < MAX_NUMNODES; ++i)
457 INIT_LIST_HEAD(&hugepage_freelists[i]);
459 hugetlb_next_nid = first_node(node_online_map);
461 for (i = 0; i < max_huge_pages; ++i) {
462 if (!alloc_fresh_huge_page())
463 break;
465 max_huge_pages = free_huge_pages = nr_huge_pages = i;
466 printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
467 return 0;
469 module_init(hugetlb_init);
471 static int __init hugetlb_setup(char *s)
473 if (sscanf(s, "%lu", &max_huge_pages) <= 0)
474 max_huge_pages = 0;
475 return 1;
477 __setup("hugepages=", hugetlb_setup);
479 static unsigned int cpuset_mems_nr(unsigned int *array)
481 int node;
482 unsigned int nr = 0;
484 for_each_node_mask(node, cpuset_current_mems_allowed)
485 nr += array[node];
487 return nr;
490 #ifdef CONFIG_SYSCTL
491 #ifdef CONFIG_HIGHMEM
492 static void try_to_free_low(unsigned long count)
494 int i;
496 for (i = 0; i < MAX_NUMNODES; ++i) {
497 struct page *page, *next;
498 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
499 if (count >= nr_huge_pages)
500 return;
501 if (PageHighMem(page))
502 continue;
503 list_del(&page->lru);
504 update_and_free_page(page);
505 free_huge_pages--;
506 free_huge_pages_node[page_to_nid(page)]--;
510 #else
511 static inline void try_to_free_low(unsigned long count)
514 #endif
516 #define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
517 static unsigned long set_max_huge_pages(unsigned long count)
519 unsigned long min_count, ret;
522 * Increase the pool size
523 * First take pages out of surplus state. Then make up the
524 * remaining difference by allocating fresh huge pages.
526 * We might race with alloc_buddy_huge_page() here and be unable
527 * to convert a surplus huge page to a normal huge page. That is
528 * not critical, though, it just means the overall size of the
529 * pool might be one hugepage larger than it needs to be, but
530 * within all the constraints specified by the sysctls.
532 spin_lock(&hugetlb_lock);
533 while (surplus_huge_pages && count > persistent_huge_pages) {
534 if (!adjust_pool_surplus(-1))
535 break;
538 while (count > persistent_huge_pages) {
539 int ret;
541 * If this allocation races such that we no longer need the
542 * page, free_huge_page will handle it by freeing the page
543 * and reducing the surplus.
545 spin_unlock(&hugetlb_lock);
546 ret = alloc_fresh_huge_page();
547 spin_lock(&hugetlb_lock);
548 if (!ret)
549 goto out;
554 * Decrease the pool size
555 * First return free pages to the buddy allocator (being careful
556 * to keep enough around to satisfy reservations). Then place
557 * pages into surplus state as needed so the pool will shrink
558 * to the desired size as pages become free.
560 * By placing pages into the surplus state independent of the
561 * overcommit value, we are allowing the surplus pool size to
562 * exceed overcommit. There are few sane options here. Since
563 * alloc_buddy_huge_page() is checking the global counter,
564 * though, we'll note that we're not allowed to exceed surplus
565 * and won't grow the pool anywhere else. Not until one of the
566 * sysctls are changed, or the surplus pages go out of use.
568 min_count = resv_huge_pages + nr_huge_pages - free_huge_pages;
569 min_count = max(count, min_count);
570 try_to_free_low(min_count);
571 while (min_count < persistent_huge_pages) {
572 struct page *page = dequeue_huge_page(NULL, 0);
573 if (!page)
574 break;
575 update_and_free_page(page);
577 while (count < persistent_huge_pages) {
578 if (!adjust_pool_surplus(1))
579 break;
581 out:
582 ret = persistent_huge_pages;
583 spin_unlock(&hugetlb_lock);
584 return ret;
587 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
588 struct file *file, void __user *buffer,
589 size_t *length, loff_t *ppos)
591 proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
592 max_huge_pages = set_max_huge_pages(max_huge_pages);
593 return 0;
596 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
597 struct file *file, void __user *buffer,
598 size_t *length, loff_t *ppos)
600 proc_dointvec(table, write, file, buffer, length, ppos);
601 if (hugepages_treat_as_movable)
602 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
603 else
604 htlb_alloc_mask = GFP_HIGHUSER;
605 return 0;
608 #endif /* CONFIG_SYSCTL */
610 int hugetlb_report_meminfo(char *buf)
612 return sprintf(buf,
613 "HugePages_Total: %5lu\n"
614 "HugePages_Free: %5lu\n"
615 "HugePages_Rsvd: %5lu\n"
616 "HugePages_Surp: %5lu\n"
617 "Hugepagesize: %5lu kB\n",
618 nr_huge_pages,
619 free_huge_pages,
620 resv_huge_pages,
621 surplus_huge_pages,
622 HPAGE_SIZE/1024);
625 int hugetlb_report_node_meminfo(int nid, char *buf)
627 return sprintf(buf,
628 "Node %d HugePages_Total: %5u\n"
629 "Node %d HugePages_Free: %5u\n",
630 nid, nr_huge_pages_node[nid],
631 nid, free_huge_pages_node[nid]);
634 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
635 unsigned long hugetlb_total_pages(void)
637 return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
641 * We cannot handle pagefaults against hugetlb pages at all. They cause
642 * handle_mm_fault() to try to instantiate regular-sized pages in the
643 * hugegpage VMA. do_page_fault() is supposed to trap this, so BUG is we get
644 * this far.
646 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
648 BUG();
649 return 0;
652 struct vm_operations_struct hugetlb_vm_ops = {
653 .fault = hugetlb_vm_op_fault,
656 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
657 int writable)
659 pte_t entry;
661 if (writable) {
662 entry =
663 pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
664 } else {
665 entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
667 entry = pte_mkyoung(entry);
668 entry = pte_mkhuge(entry);
670 return entry;
673 static void set_huge_ptep_writable(struct vm_area_struct *vma,
674 unsigned long address, pte_t *ptep)
676 pte_t entry;
678 entry = pte_mkwrite(pte_mkdirty(*ptep));
679 if (ptep_set_access_flags(vma, address, ptep, entry, 1)) {
680 update_mmu_cache(vma, address, entry);
685 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
686 struct vm_area_struct *vma)
688 pte_t *src_pte, *dst_pte, entry;
689 struct page *ptepage;
690 unsigned long addr;
691 int cow;
693 cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
695 for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
696 src_pte = huge_pte_offset(src, addr);
697 if (!src_pte)
698 continue;
699 dst_pte = huge_pte_alloc(dst, addr);
700 if (!dst_pte)
701 goto nomem;
703 /* If the pagetables are shared don't copy or take references */
704 if (dst_pte == src_pte)
705 continue;
707 spin_lock(&dst->page_table_lock);
708 spin_lock(&src->page_table_lock);
709 if (!pte_none(*src_pte)) {
710 if (cow)
711 ptep_set_wrprotect(src, addr, src_pte);
712 entry = *src_pte;
713 ptepage = pte_page(entry);
714 get_page(ptepage);
715 set_huge_pte_at(dst, addr, dst_pte, entry);
717 spin_unlock(&src->page_table_lock);
718 spin_unlock(&dst->page_table_lock);
720 return 0;
722 nomem:
723 return -ENOMEM;
726 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
727 unsigned long end)
729 struct mm_struct *mm = vma->vm_mm;
730 unsigned long address;
731 pte_t *ptep;
732 pte_t pte;
733 struct page *page;
734 struct page *tmp;
736 * A page gathering list, protected by per file i_mmap_lock. The
737 * lock is used to avoid list corruption from multiple unmapping
738 * of the same page since we are using page->lru.
740 LIST_HEAD(page_list);
742 WARN_ON(!is_vm_hugetlb_page(vma));
743 BUG_ON(start & ~HPAGE_MASK);
744 BUG_ON(end & ~HPAGE_MASK);
746 spin_lock(&mm->page_table_lock);
747 for (address = start; address < end; address += HPAGE_SIZE) {
748 ptep = huge_pte_offset(mm, address);
749 if (!ptep)
750 continue;
752 if (huge_pmd_unshare(mm, &address, ptep))
753 continue;
755 pte = huge_ptep_get_and_clear(mm, address, ptep);
756 if (pte_none(pte))
757 continue;
759 page = pte_page(pte);
760 if (pte_dirty(pte))
761 set_page_dirty(page);
762 list_add(&page->lru, &page_list);
764 spin_unlock(&mm->page_table_lock);
765 flush_tlb_range(vma, start, end);
766 list_for_each_entry_safe(page, tmp, &page_list, lru) {
767 list_del(&page->lru);
768 put_page(page);
772 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
773 unsigned long end)
776 * It is undesirable to test vma->vm_file as it should be non-null
777 * for valid hugetlb area. However, vm_file will be NULL in the error
778 * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
779 * do_mmap_pgoff() nullifies vma->vm_file before calling this function
780 * to clean up. Since no pte has actually been setup, it is safe to
781 * do nothing in this case.
783 if (vma->vm_file) {
784 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
785 __unmap_hugepage_range(vma, start, end);
786 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
790 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
791 unsigned long address, pte_t *ptep, pte_t pte)
793 struct page *old_page, *new_page;
794 int avoidcopy;
796 old_page = pte_page(pte);
798 /* If no-one else is actually using this page, avoid the copy
799 * and just make the page writable */
800 avoidcopy = (page_count(old_page) == 1);
801 if (avoidcopy) {
802 set_huge_ptep_writable(vma, address, ptep);
803 return 0;
806 page_cache_get(old_page);
807 new_page = alloc_huge_page(vma, address);
809 if (IS_ERR(new_page)) {
810 page_cache_release(old_page);
811 return -PTR_ERR(new_page);
814 spin_unlock(&mm->page_table_lock);
815 copy_huge_page(new_page, old_page, address, vma);
816 spin_lock(&mm->page_table_lock);
818 ptep = huge_pte_offset(mm, address & HPAGE_MASK);
819 if (likely(pte_same(*ptep, pte))) {
820 /* Break COW */
821 set_huge_pte_at(mm, address, ptep,
822 make_huge_pte(vma, new_page, 1));
823 /* Make the old page be freed below */
824 new_page = old_page;
826 page_cache_release(new_page);
827 page_cache_release(old_page);
828 return 0;
831 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
832 unsigned long address, pte_t *ptep, int write_access)
834 int ret = VM_FAULT_SIGBUS;
835 unsigned long idx;
836 unsigned long size;
837 struct page *page;
838 struct address_space *mapping;
839 pte_t new_pte;
841 mapping = vma->vm_file->f_mapping;
842 idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
843 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
846 * Use page lock to guard against racing truncation
847 * before we get page_table_lock.
849 retry:
850 page = find_lock_page(mapping, idx);
851 if (!page) {
852 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
853 if (idx >= size)
854 goto out;
855 page = alloc_huge_page(vma, address);
856 if (IS_ERR(page)) {
857 ret = -PTR_ERR(page);
858 goto out;
860 clear_huge_page(page, address);
862 if (vma->vm_flags & VM_SHARED) {
863 int err;
864 struct inode *inode = mapping->host;
866 err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
867 if (err) {
868 put_page(page);
869 if (err == -EEXIST)
870 goto retry;
871 goto out;
874 spin_lock(&inode->i_lock);
875 inode->i_blocks += BLOCKS_PER_HUGEPAGE;
876 spin_unlock(&inode->i_lock);
877 } else
878 lock_page(page);
881 spin_lock(&mm->page_table_lock);
882 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
883 if (idx >= size)
884 goto backout;
886 ret = 0;
887 if (!pte_none(*ptep))
888 goto backout;
890 new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
891 && (vma->vm_flags & VM_SHARED)));
892 set_huge_pte_at(mm, address, ptep, new_pte);
894 if (write_access && !(vma->vm_flags & VM_SHARED)) {
895 /* Optimization, do the COW without a second fault */
896 ret = hugetlb_cow(mm, vma, address, ptep, new_pte);
899 spin_unlock(&mm->page_table_lock);
900 unlock_page(page);
901 out:
902 return ret;
904 backout:
905 spin_unlock(&mm->page_table_lock);
906 unlock_page(page);
907 put_page(page);
908 goto out;
911 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
912 unsigned long address, int write_access)
914 pte_t *ptep;
915 pte_t entry;
916 int ret;
917 static DEFINE_MUTEX(hugetlb_instantiation_mutex);
919 ptep = huge_pte_alloc(mm, address);
920 if (!ptep)
921 return VM_FAULT_OOM;
924 * Serialize hugepage allocation and instantiation, so that we don't
925 * get spurious allocation failures if two CPUs race to instantiate
926 * the same page in the page cache.
928 mutex_lock(&hugetlb_instantiation_mutex);
929 entry = *ptep;
930 if (pte_none(entry)) {
931 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
932 mutex_unlock(&hugetlb_instantiation_mutex);
933 return ret;
936 ret = 0;
938 spin_lock(&mm->page_table_lock);
939 /* Check for a racing update before calling hugetlb_cow */
940 if (likely(pte_same(entry, *ptep)))
941 if (write_access && !pte_write(entry))
942 ret = hugetlb_cow(mm, vma, address, ptep, entry);
943 spin_unlock(&mm->page_table_lock);
944 mutex_unlock(&hugetlb_instantiation_mutex);
946 return ret;
949 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
950 struct page **pages, struct vm_area_struct **vmas,
951 unsigned long *position, int *length, int i,
952 int write)
954 unsigned long pfn_offset;
955 unsigned long vaddr = *position;
956 int remainder = *length;
958 spin_lock(&mm->page_table_lock);
959 while (vaddr < vma->vm_end && remainder) {
960 pte_t *pte;
961 struct page *page;
964 * Some archs (sparc64, sh*) have multiple pte_ts to
965 * each hugepage. We have to make * sure we get the
966 * first, for the page indexing below to work.
968 pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
970 if (!pte || pte_none(*pte) || (write && !pte_write(*pte))) {
971 int ret;
973 spin_unlock(&mm->page_table_lock);
974 ret = hugetlb_fault(mm, vma, vaddr, write);
975 spin_lock(&mm->page_table_lock);
976 if (!(ret & VM_FAULT_ERROR))
977 continue;
979 remainder = 0;
980 if (!i)
981 i = -EFAULT;
982 break;
985 pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
986 page = pte_page(*pte);
987 same_page:
988 if (pages) {
989 get_page(page);
990 pages[i] = page + pfn_offset;
993 if (vmas)
994 vmas[i] = vma;
996 vaddr += PAGE_SIZE;
997 ++pfn_offset;
998 --remainder;
999 ++i;
1000 if (vaddr < vma->vm_end && remainder &&
1001 pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
1003 * We use pfn_offset to avoid touching the pageframes
1004 * of this compound page.
1006 goto same_page;
1009 spin_unlock(&mm->page_table_lock);
1010 *length = remainder;
1011 *position = vaddr;
1013 return i;
1016 void hugetlb_change_protection(struct vm_area_struct *vma,
1017 unsigned long address, unsigned long end, pgprot_t newprot)
1019 struct mm_struct *mm = vma->vm_mm;
1020 unsigned long start = address;
1021 pte_t *ptep;
1022 pte_t pte;
1024 BUG_ON(address >= end);
1025 flush_cache_range(vma, address, end);
1027 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1028 spin_lock(&mm->page_table_lock);
1029 for (; address < end; address += HPAGE_SIZE) {
1030 ptep = huge_pte_offset(mm, address);
1031 if (!ptep)
1032 continue;
1033 if (huge_pmd_unshare(mm, &address, ptep))
1034 continue;
1035 if (!pte_none(*ptep)) {
1036 pte = huge_ptep_get_and_clear(mm, address, ptep);
1037 pte = pte_mkhuge(pte_modify(pte, newprot));
1038 set_huge_pte_at(mm, address, ptep, pte);
1041 spin_unlock(&mm->page_table_lock);
1042 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1044 flush_tlb_range(vma, start, end);
1047 struct file_region {
1048 struct list_head link;
1049 long from;
1050 long to;
1053 static long region_add(struct list_head *head, long f, long t)
1055 struct file_region *rg, *nrg, *trg;
1057 /* Locate the region we are either in or before. */
1058 list_for_each_entry(rg, head, link)
1059 if (f <= rg->to)
1060 break;
1062 /* Round our left edge to the current segment if it encloses us. */
1063 if (f > rg->from)
1064 f = rg->from;
1066 /* Check for and consume any regions we now overlap with. */
1067 nrg = rg;
1068 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
1069 if (&rg->link == head)
1070 break;
1071 if (rg->from > t)
1072 break;
1074 /* If this area reaches higher then extend our area to
1075 * include it completely. If this is not the first area
1076 * which we intend to reuse, free it. */
1077 if (rg->to > t)
1078 t = rg->to;
1079 if (rg != nrg) {
1080 list_del(&rg->link);
1081 kfree(rg);
1084 nrg->from = f;
1085 nrg->to = t;
1086 return 0;
1089 static long region_chg(struct list_head *head, long f, long t)
1091 struct file_region *rg, *nrg;
1092 long chg = 0;
1094 /* Locate the region we are before or in. */
1095 list_for_each_entry(rg, head, link)
1096 if (f <= rg->to)
1097 break;
1099 /* If we are below the current region then a new region is required.
1100 * Subtle, allocate a new region at the position but make it zero
1101 * size such that we can guarantee to record the reservation. */
1102 if (&rg->link == head || t < rg->from) {
1103 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
1104 if (!nrg)
1105 return -ENOMEM;
1106 nrg->from = f;
1107 nrg->to = f;
1108 INIT_LIST_HEAD(&nrg->link);
1109 list_add(&nrg->link, rg->link.prev);
1111 return t - f;
1114 /* Round our left edge to the current segment if it encloses us. */
1115 if (f > rg->from)
1116 f = rg->from;
1117 chg = t - f;
1119 /* Check for and consume any regions we now overlap with. */
1120 list_for_each_entry(rg, rg->link.prev, link) {
1121 if (&rg->link == head)
1122 break;
1123 if (rg->from > t)
1124 return chg;
1126 /* We overlap with this area, if it extends futher than
1127 * us then we must extend ourselves. Account for its
1128 * existing reservation. */
1129 if (rg->to > t) {
1130 chg += rg->to - t;
1131 t = rg->to;
1133 chg -= rg->to - rg->from;
1135 return chg;
1138 static long region_truncate(struct list_head *head, long end)
1140 struct file_region *rg, *trg;
1141 long chg = 0;
1143 /* Locate the region we are either in or before. */
1144 list_for_each_entry(rg, head, link)
1145 if (end <= rg->to)
1146 break;
1147 if (&rg->link == head)
1148 return 0;
1150 /* If we are in the middle of a region then adjust it. */
1151 if (end > rg->from) {
1152 chg = rg->to - end;
1153 rg->to = end;
1154 rg = list_entry(rg->link.next, typeof(*rg), link);
1157 /* Drop any remaining regions. */
1158 list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
1159 if (&rg->link == head)
1160 break;
1161 chg += rg->to - rg->from;
1162 list_del(&rg->link);
1163 kfree(rg);
1165 return chg;
1168 static int hugetlb_acct_memory(long delta)
1170 int ret = -ENOMEM;
1172 spin_lock(&hugetlb_lock);
1174 * When cpuset is configured, it breaks the strict hugetlb page
1175 * reservation as the accounting is done on a global variable. Such
1176 * reservation is completely rubbish in the presence of cpuset because
1177 * the reservation is not checked against page availability for the
1178 * current cpuset. Application can still potentially OOM'ed by kernel
1179 * with lack of free htlb page in cpuset that the task is in.
1180 * Attempt to enforce strict accounting with cpuset is almost
1181 * impossible (or too ugly) because cpuset is too fluid that
1182 * task or memory node can be dynamically moved between cpusets.
1184 * The change of semantics for shared hugetlb mapping with cpuset is
1185 * undesirable. However, in order to preserve some of the semantics,
1186 * we fall back to check against current free page availability as
1187 * a best attempt and hopefully to minimize the impact of changing
1188 * semantics that cpuset has.
1190 if (delta > 0) {
1191 if (gather_surplus_pages(delta) < 0)
1192 goto out;
1194 if (delta > cpuset_mems_nr(free_huge_pages_node))
1195 goto out;
1198 ret = 0;
1199 resv_huge_pages += delta;
1200 if (delta < 0)
1201 return_unused_surplus_pages((unsigned long) -delta);
1203 out:
1204 spin_unlock(&hugetlb_lock);
1205 return ret;
1208 int hugetlb_reserve_pages(struct inode *inode, long from, long to)
1210 long ret, chg;
1212 chg = region_chg(&inode->i_mapping->private_list, from, to);
1213 if (chg < 0)
1214 return chg;
1216 if (hugetlb_get_quota(inode->i_mapping, chg))
1217 return -ENOSPC;
1218 ret = hugetlb_acct_memory(chg);
1219 if (ret < 0) {
1220 hugetlb_put_quota(inode->i_mapping, chg);
1221 return ret;
1223 region_add(&inode->i_mapping->private_list, from, to);
1224 return 0;
1227 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
1229 long chg = region_truncate(&inode->i_mapping->private_list, offset);
1231 spin_lock(&inode->i_lock);
1232 inode->i_blocks -= BLOCKS_PER_HUGEPAGE * freed;
1233 spin_unlock(&inode->i_lock);
1235 hugetlb_put_quota(inode->i_mapping, (chg - freed));
1236 hugetlb_acct_memory(-(chg - freed));