d36e1f11a5f267d441ffda665d4b6a6275c3d451
[linux-2.6.git] / mm / hugetlb.c
1 /*
2  * Generic hugetlb support.
3  * (C) William Irwin, April 2004
4  */
5 #include <linux/gfp.h>
6 #include <linux/list.h>
7 #include <linux/init.h>
8 #include <linux/module.h>
9 #include <linux/mm.h>
10 #include <linux/sysctl.h>
11 #include <linux/highmem.h>
12 #include <linux/nodemask.h>
13 #include <linux/pagemap.h>
14 #include <linux/mempolicy.h>
15 #include <linux/cpuset.h>
16 #include <linux/mutex.h>
17
18 #include <asm/page.h>
19 #include <asm/pgtable.h>
20
21 #include <linux/hugetlb.h>
22 #include "internal.h"
23
24 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
25 static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;
26 static unsigned long surplus_huge_pages;
27 static unsigned long nr_overcommit_huge_pages;
28 unsigned long max_huge_pages;
29 unsigned long sysctl_overcommit_huge_pages;
30 static struct list_head hugepage_freelists[MAX_NUMNODES];
31 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
32 static unsigned int free_huge_pages_node[MAX_NUMNODES];
33 static unsigned int surplus_huge_pages_node[MAX_NUMNODES];
34 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
35 unsigned long hugepages_treat_as_movable;
36 static int hugetlb_next_nid;
37
38 /*
39  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
40  */
41 static DEFINE_SPINLOCK(hugetlb_lock);
42
43 static void clear_huge_page(struct page *page, unsigned long addr)
44 {
45         int i;
46
47         might_sleep();
48         for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
49                 cond_resched();
50                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
51         }
52 }
53
54 static void copy_huge_page(struct page *dst, struct page *src,
55                            unsigned long addr, struct vm_area_struct *vma)
56 {
57         int i;
58
59         might_sleep();
60         for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
61                 cond_resched();
62                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
63         }
64 }
65
66 static void enqueue_huge_page(struct page *page)
67 {
68         int nid = page_to_nid(page);
69         list_add(&page->lru, &hugepage_freelists[nid]);
70         free_huge_pages++;
71         free_huge_pages_node[nid]++;
72 }
73
74 static struct page *dequeue_huge_page(void)
75 {
76         int nid;
77         struct page *page = NULL;
78
79         for (nid = 0; nid < MAX_NUMNODES; ++nid) {
80                 if (!list_empty(&hugepage_freelists[nid])) {
81                         page = list_entry(hugepage_freelists[nid].next,
82                                           struct page, lru);
83                         list_del(&page->lru);
84                         free_huge_pages--;
85                         free_huge_pages_node[nid]--;
86                         break;
87                 }
88         }
89         return page;
90 }
91
92 static struct page *dequeue_huge_page_vma(struct vm_area_struct *vma,
93                                 unsigned long address)
94 {
95         int nid;
96         struct page *page = NULL;
97         struct mempolicy *mpol;
98         nodemask_t *nodemask;
99         struct zonelist *zonelist = huge_zonelist(vma, address,
100                                         htlb_alloc_mask, &mpol, &nodemask);
101         struct zone *zone;
102         struct zoneref *z;
103
104         for_each_zone_zonelist_nodemask(zone, z, zonelist,
105                                                 MAX_NR_ZONES - 1, nodemask) {
106                 nid = zone_to_nid(zone);
107                 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
108                     !list_empty(&hugepage_freelists[nid])) {
109                         page = list_entry(hugepage_freelists[nid].next,
110                                           struct page, lru);
111                         list_del(&page->lru);
112                         free_huge_pages--;
113                         free_huge_pages_node[nid]--;
114                         if (vma && vma->vm_flags & VM_MAYSHARE)
115                                 resv_huge_pages--;
116                         break;
117                 }
118         }
119         mpol_cond_put(mpol);
120         return page;
121 }
122
123 static void update_and_free_page(struct page *page)
124 {
125         int i;
126         nr_huge_pages--;
127         nr_huge_pages_node[page_to_nid(page)]--;
128         for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
129                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
130                                 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
131                                 1 << PG_private | 1<< PG_writeback);
132         }
133         set_compound_page_dtor(page, NULL);
134         set_page_refcounted(page);
135         __free_pages(page, HUGETLB_PAGE_ORDER);
136 }
137
138 static void free_huge_page(struct page *page)
139 {
140         int nid = page_to_nid(page);
141         struct address_space *mapping;
142
143         mapping = (struct address_space *) page_private(page);
144         set_page_private(page, 0);
145         BUG_ON(page_count(page));
146         INIT_LIST_HEAD(&page->lru);
147
148         spin_lock(&hugetlb_lock);
149         if (surplus_huge_pages_node[nid]) {
150                 update_and_free_page(page);
151                 surplus_huge_pages--;
152                 surplus_huge_pages_node[nid]--;
153         } else {
154                 enqueue_huge_page(page);
155         }
156         spin_unlock(&hugetlb_lock);
157         if (mapping)
158                 hugetlb_put_quota(mapping, 1);
159 }
160
161 /*
162  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
163  * balanced by operating on them in a round-robin fashion.
164  * Returns 1 if an adjustment was made.
165  */
166 static int adjust_pool_surplus(int delta)
167 {
168         static int prev_nid;
169         int nid = prev_nid;
170         int ret = 0;
171
172         VM_BUG_ON(delta != -1 && delta != 1);
173         do {
174                 nid = next_node(nid, node_online_map);
175                 if (nid == MAX_NUMNODES)
176                         nid = first_node(node_online_map);
177
178                 /* To shrink on this node, there must be a surplus page */
179                 if (delta < 0 && !surplus_huge_pages_node[nid])
180                         continue;
181                 /* Surplus cannot exceed the total number of pages */
182                 if (delta > 0 && surplus_huge_pages_node[nid] >=
183                                                 nr_huge_pages_node[nid])
184                         continue;
185
186                 surplus_huge_pages += delta;
187                 surplus_huge_pages_node[nid] += delta;
188                 ret = 1;
189                 break;
190         } while (nid != prev_nid);
191
192         prev_nid = nid;
193         return ret;
194 }
195
196 static struct page *alloc_fresh_huge_page_node(int nid)
197 {
198         struct page *page;
199
200         page = alloc_pages_node(nid,
201                 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|__GFP_NOWARN,
202                 HUGETLB_PAGE_ORDER);
203         if (page) {
204                 set_compound_page_dtor(page, free_huge_page);
205                 spin_lock(&hugetlb_lock);
206                 nr_huge_pages++;
207                 nr_huge_pages_node[nid]++;
208                 spin_unlock(&hugetlb_lock);
209                 put_page(page); /* free it into the hugepage allocator */
210         }
211
212         return page;
213 }
214
215 static int alloc_fresh_huge_page(void)
216 {
217         struct page *page;
218         int start_nid;
219         int next_nid;
220         int ret = 0;
221
222         start_nid = hugetlb_next_nid;
223
224         do {
225                 page = alloc_fresh_huge_page_node(hugetlb_next_nid);
226                 if (page)
227                         ret = 1;
228                 /*
229                  * Use a helper variable to find the next node and then
230                  * copy it back to hugetlb_next_nid afterwards:
231                  * otherwise there's a window in which a racer might
232                  * pass invalid nid MAX_NUMNODES to alloc_pages_node.
233                  * But we don't need to use a spin_lock here: it really
234                  * doesn't matter if occasionally a racer chooses the
235                  * same nid as we do.  Move nid forward in the mask even
236                  * if we just successfully allocated a hugepage so that
237                  * the next caller gets hugepages on the next node.
238                  */
239                 next_nid = next_node(hugetlb_next_nid, node_online_map);
240                 if (next_nid == MAX_NUMNODES)
241                         next_nid = first_node(node_online_map);
242                 hugetlb_next_nid = next_nid;
243         } while (!page && hugetlb_next_nid != start_nid);
244
245         if (ret)
246                 count_vm_event(HTLB_BUDDY_PGALLOC);
247         else
248                 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
249
250         return ret;
251 }
252
253 static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma,
254                                                 unsigned long address)
255 {
256         struct page *page;
257         unsigned int nid;
258
259         /*
260          * Assume we will successfully allocate the surplus page to
261          * prevent racing processes from causing the surplus to exceed
262          * overcommit
263          *
264          * This however introduces a different race, where a process B
265          * tries to grow the static hugepage pool while alloc_pages() is
266          * called by process A. B will only examine the per-node
267          * counters in determining if surplus huge pages can be
268          * converted to normal huge pages in adjust_pool_surplus(). A
269          * won't be able to increment the per-node counter, until the
270          * lock is dropped by B, but B doesn't drop hugetlb_lock until
271          * no more huge pages can be converted from surplus to normal
272          * state (and doesn't try to convert again). Thus, we have a
273          * case where a surplus huge page exists, the pool is grown, and
274          * the surplus huge page still exists after, even though it
275          * should just have been converted to a normal huge page. This
276          * does not leak memory, though, as the hugepage will be freed
277          * once it is out of use. It also does not allow the counters to
278          * go out of whack in adjust_pool_surplus() as we don't modify
279          * the node values until we've gotten the hugepage and only the
280          * per-node value is checked there.
281          */
282         spin_lock(&hugetlb_lock);
283         if (surplus_huge_pages >= nr_overcommit_huge_pages) {
284                 spin_unlock(&hugetlb_lock);
285                 return NULL;
286         } else {
287                 nr_huge_pages++;
288                 surplus_huge_pages++;
289         }
290         spin_unlock(&hugetlb_lock);
291
292         page = alloc_pages(htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
293                                         HUGETLB_PAGE_ORDER);
294
295         spin_lock(&hugetlb_lock);
296         if (page) {
297                 /*
298                  * This page is now managed by the hugetlb allocator and has
299                  * no users -- drop the buddy allocator's reference.
300                  */
301                 put_page_testzero(page);
302                 VM_BUG_ON(page_count(page));
303                 nid = page_to_nid(page);
304                 set_compound_page_dtor(page, free_huge_page);
305                 /*
306                  * We incremented the global counters already
307                  */
308                 nr_huge_pages_node[nid]++;
309                 surplus_huge_pages_node[nid]++;
310                 __count_vm_event(HTLB_BUDDY_PGALLOC);
311         } else {
312                 nr_huge_pages--;
313                 surplus_huge_pages--;
314                 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
315         }
316         spin_unlock(&hugetlb_lock);
317
318         return page;
319 }
320
321 /*
322  * Increase the hugetlb pool such that it can accomodate a reservation
323  * of size 'delta'.
324  */
325 static int gather_surplus_pages(int delta)
326 {
327         struct list_head surplus_list;
328         struct page *page, *tmp;
329         int ret, i;
330         int needed, allocated;
331
332         needed = (resv_huge_pages + delta) - free_huge_pages;
333         if (needed <= 0) {
334                 resv_huge_pages += delta;
335                 return 0;
336         }
337
338         allocated = 0;
339         INIT_LIST_HEAD(&surplus_list);
340
341         ret = -ENOMEM;
342 retry:
343         spin_unlock(&hugetlb_lock);
344         for (i = 0; i < needed; i++) {
345                 page = alloc_buddy_huge_page(NULL, 0);
346                 if (!page) {
347                         /*
348                          * We were not able to allocate enough pages to
349                          * satisfy the entire reservation so we free what
350                          * we've allocated so far.
351                          */
352                         spin_lock(&hugetlb_lock);
353                         needed = 0;
354                         goto free;
355                 }
356
357                 list_add(&page->lru, &surplus_list);
358         }
359         allocated += needed;
360
361         /*
362          * After retaking hugetlb_lock, we need to recalculate 'needed'
363          * because either resv_huge_pages or free_huge_pages may have changed.
364          */
365         spin_lock(&hugetlb_lock);
366         needed = (resv_huge_pages + delta) - (free_huge_pages + allocated);
367         if (needed > 0)
368                 goto retry;
369
370         /*
371          * The surplus_list now contains _at_least_ the number of extra pages
372          * needed to accomodate the reservation.  Add the appropriate number
373          * of pages to the hugetlb pool and free the extras back to the buddy
374          * allocator.  Commit the entire reservation here to prevent another
375          * process from stealing the pages as they are added to the pool but
376          * before they are reserved.
377          */
378         needed += allocated;
379         resv_huge_pages += delta;
380         ret = 0;
381 free:
382         /* Free the needed pages to the hugetlb pool */
383         list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
384                 if ((--needed) < 0)
385                         break;
386                 list_del(&page->lru);
387                 enqueue_huge_page(page);
388         }
389
390         /* Free unnecessary surplus pages to the buddy allocator */
391         if (!list_empty(&surplus_list)) {
392                 spin_unlock(&hugetlb_lock);
393                 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
394                         list_del(&page->lru);
395                         /*
396                          * The page has a reference count of zero already, so
397                          * call free_huge_page directly instead of using
398                          * put_page.  This must be done with hugetlb_lock
399                          * unlocked which is safe because free_huge_page takes
400                          * hugetlb_lock before deciding how to free the page.
401                          */
402                         free_huge_page(page);
403                 }
404                 spin_lock(&hugetlb_lock);
405         }
406
407         return ret;
408 }
409
410 /*
411  * When releasing a hugetlb pool reservation, any surplus pages that were
412  * allocated to satisfy the reservation must be explicitly freed if they were
413  * never used.
414  */
415 static void return_unused_surplus_pages(unsigned long unused_resv_pages)
416 {
417         static int nid = -1;
418         struct page *page;
419         unsigned long nr_pages;
420
421         /*
422          * We want to release as many surplus pages as possible, spread
423          * evenly across all nodes. Iterate across all nodes until we
424          * can no longer free unreserved surplus pages. This occurs when
425          * the nodes with surplus pages have no free pages.
426          */
427         unsigned long remaining_iterations = num_online_nodes();
428
429         /* Uncommit the reservation */
430         resv_huge_pages -= unused_resv_pages;
431
432         nr_pages = min(unused_resv_pages, surplus_huge_pages);
433
434         while (remaining_iterations-- && nr_pages) {
435                 nid = next_node(nid, node_online_map);
436                 if (nid == MAX_NUMNODES)
437                         nid = first_node(node_online_map);
438
439                 if (!surplus_huge_pages_node[nid])
440                         continue;
441
442                 if (!list_empty(&hugepage_freelists[nid])) {
443                         page = list_entry(hugepage_freelists[nid].next,
444                                           struct page, lru);
445                         list_del(&page->lru);
446                         update_and_free_page(page);
447                         free_huge_pages--;
448                         free_huge_pages_node[nid]--;
449                         surplus_huge_pages--;
450                         surplus_huge_pages_node[nid]--;
451                         nr_pages--;
452                         remaining_iterations = num_online_nodes();
453                 }
454         }
455 }
456
457
458 static struct page *alloc_huge_page_shared(struct vm_area_struct *vma,
459                                                 unsigned long addr)
460 {
461         struct page *page;
462
463         spin_lock(&hugetlb_lock);
464         page = dequeue_huge_page_vma(vma, addr);
465         spin_unlock(&hugetlb_lock);
466         return page ? page : ERR_PTR(-VM_FAULT_OOM);
467 }
468
469 static struct page *alloc_huge_page_private(struct vm_area_struct *vma,
470                                                 unsigned long addr)
471 {
472         struct page *page = NULL;
473
474         if (hugetlb_get_quota(vma->vm_file->f_mapping, 1))
475                 return ERR_PTR(-VM_FAULT_SIGBUS);
476
477         spin_lock(&hugetlb_lock);
478         if (free_huge_pages > resv_huge_pages)
479                 page = dequeue_huge_page_vma(vma, addr);
480         spin_unlock(&hugetlb_lock);
481         if (!page) {
482                 page = alloc_buddy_huge_page(vma, addr);
483                 if (!page) {
484                         hugetlb_put_quota(vma->vm_file->f_mapping, 1);
485                         return ERR_PTR(-VM_FAULT_OOM);
486                 }
487         }
488         return page;
489 }
490
491 static struct page *alloc_huge_page(struct vm_area_struct *vma,
492                                     unsigned long addr)
493 {
494         struct page *page;
495         struct address_space *mapping = vma->vm_file->f_mapping;
496
497         if (vma->vm_flags & VM_MAYSHARE)
498                 page = alloc_huge_page_shared(vma, addr);
499         else
500                 page = alloc_huge_page_private(vma, addr);
501
502         if (!IS_ERR(page)) {
503                 set_page_refcounted(page);
504                 set_page_private(page, (unsigned long) mapping);
505         }
506         return page;
507 }
508
509 static int __init hugetlb_init(void)
510 {
511         unsigned long i;
512
513         if (HPAGE_SHIFT == 0)
514                 return 0;
515
516         for (i = 0; i < MAX_NUMNODES; ++i)
517                 INIT_LIST_HEAD(&hugepage_freelists[i]);
518
519         hugetlb_next_nid = first_node(node_online_map);
520
521         for (i = 0; i < max_huge_pages; ++i) {
522                 if (!alloc_fresh_huge_page())
523                         break;
524         }
525         max_huge_pages = free_huge_pages = nr_huge_pages = i;
526         printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
527         return 0;
528 }
529 module_init(hugetlb_init);
530
531 static int __init hugetlb_setup(char *s)
532 {
533         if (sscanf(s, "%lu", &max_huge_pages) <= 0)
534                 max_huge_pages = 0;
535         return 1;
536 }
537 __setup("hugepages=", hugetlb_setup);
538
539 static unsigned int cpuset_mems_nr(unsigned int *array)
540 {
541         int node;
542         unsigned int nr = 0;
543
544         for_each_node_mask(node, cpuset_current_mems_allowed)
545                 nr += array[node];
546
547         return nr;
548 }
549
550 #ifdef CONFIG_SYSCTL
551 #ifdef CONFIG_HIGHMEM
552 static void try_to_free_low(unsigned long count)
553 {
554         int i;
555
556         for (i = 0; i < MAX_NUMNODES; ++i) {
557                 struct page *page, *next;
558                 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
559                         if (count >= nr_huge_pages)
560                                 return;
561                         if (PageHighMem(page))
562                                 continue;
563                         list_del(&page->lru);
564                         update_and_free_page(page);
565                         free_huge_pages--;
566                         free_huge_pages_node[page_to_nid(page)]--;
567                 }
568         }
569 }
570 #else
571 static inline void try_to_free_low(unsigned long count)
572 {
573 }
574 #endif
575
576 #define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
577 static unsigned long set_max_huge_pages(unsigned long count)
578 {
579         unsigned long min_count, ret;
580
581         /*
582          * Increase the pool size
583          * First take pages out of surplus state.  Then make up the
584          * remaining difference by allocating fresh huge pages.
585          *
586          * We might race with alloc_buddy_huge_page() here and be unable
587          * to convert a surplus huge page to a normal huge page. That is
588          * not critical, though, it just means the overall size of the
589          * pool might be one hugepage larger than it needs to be, but
590          * within all the constraints specified by the sysctls.
591          */
592         spin_lock(&hugetlb_lock);
593         while (surplus_huge_pages && count > persistent_huge_pages) {
594                 if (!adjust_pool_surplus(-1))
595                         break;
596         }
597
598         while (count > persistent_huge_pages) {
599                 int ret;
600                 /*
601                  * If this allocation races such that we no longer need the
602                  * page, free_huge_page will handle it by freeing the page
603                  * and reducing the surplus.
604                  */
605                 spin_unlock(&hugetlb_lock);
606                 ret = alloc_fresh_huge_page();
607                 spin_lock(&hugetlb_lock);
608                 if (!ret)
609                         goto out;
610
611         }
612
613         /*
614          * Decrease the pool size
615          * First return free pages to the buddy allocator (being careful
616          * to keep enough around to satisfy reservations).  Then place
617          * pages into surplus state as needed so the pool will shrink
618          * to the desired size as pages become free.
619          *
620          * By placing pages into the surplus state independent of the
621          * overcommit value, we are allowing the surplus pool size to
622          * exceed overcommit. There are few sane options here. Since
623          * alloc_buddy_huge_page() is checking the global counter,
624          * though, we'll note that we're not allowed to exceed surplus
625          * and won't grow the pool anywhere else. Not until one of the
626          * sysctls are changed, or the surplus pages go out of use.
627          */
628         min_count = resv_huge_pages + nr_huge_pages - free_huge_pages;
629         min_count = max(count, min_count);
630         try_to_free_low(min_count);
631         while (min_count < persistent_huge_pages) {
632                 struct page *page = dequeue_huge_page();
633                 if (!page)
634                         break;
635                 update_and_free_page(page);
636         }
637         while (count < persistent_huge_pages) {
638                 if (!adjust_pool_surplus(1))
639                         break;
640         }
641 out:
642         ret = persistent_huge_pages;
643         spin_unlock(&hugetlb_lock);
644         return ret;
645 }
646
647 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
648                            struct file *file, void __user *buffer,
649                            size_t *length, loff_t *ppos)
650 {
651         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
652         max_huge_pages = set_max_huge_pages(max_huge_pages);
653         return 0;
654 }
655
656 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
657                         struct file *file, void __user *buffer,
658                         size_t *length, loff_t *ppos)
659 {
660         proc_dointvec(table, write, file, buffer, length, ppos);
661         if (hugepages_treat_as_movable)
662                 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
663         else
664                 htlb_alloc_mask = GFP_HIGHUSER;
665         return 0;
666 }
667
668 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
669                         struct file *file, void __user *buffer,
670                         size_t *length, loff_t *ppos)
671 {
672         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
673         spin_lock(&hugetlb_lock);
674         nr_overcommit_huge_pages = sysctl_overcommit_huge_pages;
675         spin_unlock(&hugetlb_lock);
676         return 0;
677 }
678
679 #endif /* CONFIG_SYSCTL */
680
681 int hugetlb_report_meminfo(char *buf)
682 {
683         return sprintf(buf,
684                         "HugePages_Total: %5lu\n"
685                         "HugePages_Free:  %5lu\n"
686                         "HugePages_Rsvd:  %5lu\n"
687                         "HugePages_Surp:  %5lu\n"
688                         "Hugepagesize:    %5lu kB\n",
689                         nr_huge_pages,
690                         free_huge_pages,
691                         resv_huge_pages,
692                         surplus_huge_pages,
693                         HPAGE_SIZE/1024);
694 }
695
696 int hugetlb_report_node_meminfo(int nid, char *buf)
697 {
698         return sprintf(buf,
699                 "Node %d HugePages_Total: %5u\n"
700                 "Node %d HugePages_Free:  %5u\n"
701                 "Node %d HugePages_Surp:  %5u\n",
702                 nid, nr_huge_pages_node[nid],
703                 nid, free_huge_pages_node[nid],
704                 nid, surplus_huge_pages_node[nid]);
705 }
706
707 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
708 unsigned long hugetlb_total_pages(void)
709 {
710         return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
711 }
712
713 /*
714  * We cannot handle pagefaults against hugetlb pages at all.  They cause
715  * handle_mm_fault() to try to instantiate regular-sized pages in the
716  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
717  * this far.
718  */
719 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
720 {
721         BUG();
722         return 0;
723 }
724
725 struct vm_operations_struct hugetlb_vm_ops = {
726         .fault = hugetlb_vm_op_fault,
727 };
728
729 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
730                                 int writable)
731 {
732         pte_t entry;
733
734         if (writable) {
735                 entry =
736                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
737         } else {
738                 entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
739         }
740         entry = pte_mkyoung(entry);
741         entry = pte_mkhuge(entry);
742
743         return entry;
744 }
745
746 static void set_huge_ptep_writable(struct vm_area_struct *vma,
747                                    unsigned long address, pte_t *ptep)
748 {
749         pte_t entry;
750
751         entry = pte_mkwrite(pte_mkdirty(*ptep));
752         if (ptep_set_access_flags(vma, address, ptep, entry, 1)) {
753                 update_mmu_cache(vma, address, entry);
754         }
755 }
756
757
758 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
759                             struct vm_area_struct *vma)
760 {
761         pte_t *src_pte, *dst_pte, entry;
762         struct page *ptepage;
763         unsigned long addr;
764         int cow;
765
766         cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
767
768         for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
769                 src_pte = huge_pte_offset(src, addr);
770                 if (!src_pte)
771                         continue;
772                 dst_pte = huge_pte_alloc(dst, addr);
773                 if (!dst_pte)
774                         goto nomem;
775
776                 /* If the pagetables are shared don't copy or take references */
777                 if (dst_pte == src_pte)
778                         continue;
779
780                 spin_lock(&dst->page_table_lock);
781                 spin_lock(&src->page_table_lock);
782                 if (!pte_none(*src_pte)) {
783                         if (cow)
784                                 ptep_set_wrprotect(src, addr, src_pte);
785                         entry = *src_pte;
786                         ptepage = pte_page(entry);
787                         get_page(ptepage);
788                         set_huge_pte_at(dst, addr, dst_pte, entry);
789                 }
790                 spin_unlock(&src->page_table_lock);
791                 spin_unlock(&dst->page_table_lock);
792         }
793         return 0;
794
795 nomem:
796         return -ENOMEM;
797 }
798
799 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
800                             unsigned long end)
801 {
802         struct mm_struct *mm = vma->vm_mm;
803         unsigned long address;
804         pte_t *ptep;
805         pte_t pte;
806         struct page *page;
807         struct page *tmp;
808         /*
809          * A page gathering list, protected by per file i_mmap_lock. The
810          * lock is used to avoid list corruption from multiple unmapping
811          * of the same page since we are using page->lru.
812          */
813         LIST_HEAD(page_list);
814
815         WARN_ON(!is_vm_hugetlb_page(vma));
816         BUG_ON(start & ~HPAGE_MASK);
817         BUG_ON(end & ~HPAGE_MASK);
818
819         spin_lock(&mm->page_table_lock);
820         for (address = start; address < end; address += HPAGE_SIZE) {
821                 ptep = huge_pte_offset(mm, address);
822                 if (!ptep)
823                         continue;
824
825                 if (huge_pmd_unshare(mm, &address, ptep))
826                         continue;
827
828                 pte = huge_ptep_get_and_clear(mm, address, ptep);
829                 if (pte_none(pte))
830                         continue;
831
832                 page = pte_page(pte);
833                 if (pte_dirty(pte))
834                         set_page_dirty(page);
835                 list_add(&page->lru, &page_list);
836         }
837         spin_unlock(&mm->page_table_lock);
838         flush_tlb_range(vma, start, end);
839         list_for_each_entry_safe(page, tmp, &page_list, lru) {
840                 list_del(&page->lru);
841                 put_page(page);
842         }
843 }
844
845 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
846                           unsigned long end)
847 {
848         /*
849          * It is undesirable to test vma->vm_file as it should be non-null
850          * for valid hugetlb area. However, vm_file will be NULL in the error
851          * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
852          * do_mmap_pgoff() nullifies vma->vm_file before calling this function
853          * to clean up. Since no pte has actually been setup, it is safe to
854          * do nothing in this case.
855          */
856         if (vma->vm_file) {
857                 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
858                 __unmap_hugepage_range(vma, start, end);
859                 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
860         }
861 }
862
863 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
864                         unsigned long address, pte_t *ptep, pte_t pte)
865 {
866         struct page *old_page, *new_page;
867         int avoidcopy;
868
869         old_page = pte_page(pte);
870
871         /* If no-one else is actually using this page, avoid the copy
872          * and just make the page writable */
873         avoidcopy = (page_count(old_page) == 1);
874         if (avoidcopy) {
875                 set_huge_ptep_writable(vma, address, ptep);
876                 return 0;
877         }
878
879         page_cache_get(old_page);
880         new_page = alloc_huge_page(vma, address);
881
882         if (IS_ERR(new_page)) {
883                 page_cache_release(old_page);
884                 return -PTR_ERR(new_page);
885         }
886
887         spin_unlock(&mm->page_table_lock);
888         copy_huge_page(new_page, old_page, address, vma);
889         __SetPageUptodate(new_page);
890         spin_lock(&mm->page_table_lock);
891
892         ptep = huge_pte_offset(mm, address & HPAGE_MASK);
893         if (likely(pte_same(*ptep, pte))) {
894                 /* Break COW */
895                 set_huge_pte_at(mm, address, ptep,
896                                 make_huge_pte(vma, new_page, 1));
897                 /* Make the old page be freed below */
898                 new_page = old_page;
899         }
900         page_cache_release(new_page);
901         page_cache_release(old_page);
902         return 0;
903 }
904
905 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
906                         unsigned long address, pte_t *ptep, int write_access)
907 {
908         int ret = VM_FAULT_SIGBUS;
909         unsigned long idx;
910         unsigned long size;
911         struct page *page;
912         struct address_space *mapping;
913         pte_t new_pte;
914
915         mapping = vma->vm_file->f_mapping;
916         idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
917                 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
918
919         /*
920          * Use page lock to guard against racing truncation
921          * before we get page_table_lock.
922          */
923 retry:
924         page = find_lock_page(mapping, idx);
925         if (!page) {
926                 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
927                 if (idx >= size)
928                         goto out;
929                 page = alloc_huge_page(vma, address);
930                 if (IS_ERR(page)) {
931                         ret = -PTR_ERR(page);
932                         goto out;
933                 }
934                 clear_huge_page(page, address);
935                 __SetPageUptodate(page);
936
937                 if (vma->vm_flags & VM_SHARED) {
938                         int err;
939                         struct inode *inode = mapping->host;
940
941                         err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
942                         if (err) {
943                                 put_page(page);
944                                 if (err == -EEXIST)
945                                         goto retry;
946                                 goto out;
947                         }
948
949                         spin_lock(&inode->i_lock);
950                         inode->i_blocks += BLOCKS_PER_HUGEPAGE;
951                         spin_unlock(&inode->i_lock);
952                 } else
953                         lock_page(page);
954         }
955
956         spin_lock(&mm->page_table_lock);
957         size = i_size_read(mapping->host) >> HPAGE_SHIFT;
958         if (idx >= size)
959                 goto backout;
960
961         ret = 0;
962         if (!pte_none(*ptep))
963                 goto backout;
964
965         new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
966                                 && (vma->vm_flags & VM_SHARED)));
967         set_huge_pte_at(mm, address, ptep, new_pte);
968
969         if (write_access && !(vma->vm_flags & VM_SHARED)) {
970                 /* Optimization, do the COW without a second fault */
971                 ret = hugetlb_cow(mm, vma, address, ptep, new_pte);
972         }
973
974         spin_unlock(&mm->page_table_lock);
975         unlock_page(page);
976 out:
977         return ret;
978
979 backout:
980         spin_unlock(&mm->page_table_lock);
981         unlock_page(page);
982         put_page(page);
983         goto out;
984 }
985
986 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
987                         unsigned long address, int write_access)
988 {
989         pte_t *ptep;
990         pte_t entry;
991         int ret;
992         static DEFINE_MUTEX(hugetlb_instantiation_mutex);
993
994         ptep = huge_pte_alloc(mm, address);
995         if (!ptep)
996                 return VM_FAULT_OOM;
997
998         /*
999          * Serialize hugepage allocation and instantiation, so that we don't
1000          * get spurious allocation failures if two CPUs race to instantiate
1001          * the same page in the page cache.
1002          */
1003         mutex_lock(&hugetlb_instantiation_mutex);
1004         entry = *ptep;
1005         if (pte_none(entry)) {
1006                 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
1007                 mutex_unlock(&hugetlb_instantiation_mutex);
1008                 return ret;
1009         }
1010
1011         ret = 0;
1012
1013         spin_lock(&mm->page_table_lock);
1014         /* Check for a racing update before calling hugetlb_cow */
1015         if (likely(pte_same(entry, *ptep)))
1016                 if (write_access && !pte_write(entry))
1017                         ret = hugetlb_cow(mm, vma, address, ptep, entry);
1018         spin_unlock(&mm->page_table_lock);
1019         mutex_unlock(&hugetlb_instantiation_mutex);
1020
1021         return ret;
1022 }
1023
1024 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
1025                         struct page **pages, struct vm_area_struct **vmas,
1026                         unsigned long *position, int *length, int i,
1027                         int write)
1028 {
1029         unsigned long pfn_offset;
1030         unsigned long vaddr = *position;
1031         int remainder = *length;
1032
1033         spin_lock(&mm->page_table_lock);
1034         while (vaddr < vma->vm_end && remainder) {
1035                 pte_t *pte;
1036                 struct page *page;
1037
1038                 /*
1039                  * Some archs (sparc64, sh*) have multiple pte_ts to
1040                  * each hugepage.  We have to make * sure we get the
1041                  * first, for the page indexing below to work.
1042                  */
1043                 pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
1044
1045                 if (!pte || pte_none(*pte) || (write && !pte_write(*pte))) {
1046                         int ret;
1047
1048                         spin_unlock(&mm->page_table_lock);
1049                         ret = hugetlb_fault(mm, vma, vaddr, write);
1050                         spin_lock(&mm->page_table_lock);
1051                         if (!(ret & VM_FAULT_ERROR))
1052                                 continue;
1053
1054                         remainder = 0;
1055                         if (!i)
1056                                 i = -EFAULT;
1057                         break;
1058                 }
1059
1060                 pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
1061                 page = pte_page(*pte);
1062 same_page:
1063                 if (pages) {
1064                         get_page(page);
1065                         pages[i] = page + pfn_offset;
1066                 }
1067
1068                 if (vmas)
1069                         vmas[i] = vma;
1070
1071                 vaddr += PAGE_SIZE;
1072                 ++pfn_offset;
1073                 --remainder;
1074                 ++i;
1075                 if (vaddr < vma->vm_end && remainder &&
1076                                 pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
1077                         /*
1078                          * We use pfn_offset to avoid touching the pageframes
1079                          * of this compound page.
1080                          */
1081                         goto same_page;
1082                 }
1083         }
1084         spin_unlock(&mm->page_table_lock);
1085         *length = remainder;
1086         *position = vaddr;
1087
1088         return i;
1089 }
1090
1091 void hugetlb_change_protection(struct vm_area_struct *vma,
1092                 unsigned long address, unsigned long end, pgprot_t newprot)
1093 {
1094         struct mm_struct *mm = vma->vm_mm;
1095         unsigned long start = address;
1096         pte_t *ptep;
1097         pte_t pte;
1098
1099         BUG_ON(address >= end);
1100         flush_cache_range(vma, address, end);
1101
1102         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1103         spin_lock(&mm->page_table_lock);
1104         for (; address < end; address += HPAGE_SIZE) {
1105                 ptep = huge_pte_offset(mm, address);
1106                 if (!ptep)
1107                         continue;
1108                 if (huge_pmd_unshare(mm, &address, ptep))
1109                         continue;
1110                 if (!pte_none(*ptep)) {
1111                         pte = huge_ptep_get_and_clear(mm, address, ptep);
1112                         pte = pte_mkhuge(pte_modify(pte, newprot));
1113                         set_huge_pte_at(mm, address, ptep, pte);
1114                 }
1115         }
1116         spin_unlock(&mm->page_table_lock);
1117         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1118
1119         flush_tlb_range(vma, start, end);
1120 }
1121
1122 struct file_region {
1123         struct list_head link;
1124         long from;
1125         long to;
1126 };
1127
1128 static long region_add(struct list_head *head, long f, long t)
1129 {
1130         struct file_region *rg, *nrg, *trg;
1131
1132         /* Locate the region we are either in or before. */
1133         list_for_each_entry(rg, head, link)
1134                 if (f <= rg->to)
1135                         break;
1136
1137         /* Round our left edge to the current segment if it encloses us. */
1138         if (f > rg->from)
1139                 f = rg->from;
1140
1141         /* Check for and consume any regions we now overlap with. */
1142         nrg = rg;
1143         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
1144                 if (&rg->link == head)
1145                         break;
1146                 if (rg->from > t)
1147                         break;
1148
1149                 /* If this area reaches higher then extend our area to
1150                  * include it completely.  If this is not the first area
1151                  * which we intend to reuse, free it. */
1152                 if (rg->to > t)
1153                         t = rg->to;
1154                 if (rg != nrg) {
1155                         list_del(&rg->link);
1156                         kfree(rg);
1157                 }
1158         }
1159         nrg->from = f;
1160         nrg->to = t;
1161         return 0;
1162 }
1163
1164 static long region_chg(struct list_head *head, long f, long t)
1165 {
1166         struct file_region *rg, *nrg;
1167         long chg = 0;
1168
1169         /* Locate the region we are before or in. */
1170         list_for_each_entry(rg, head, link)
1171                 if (f <= rg->to)
1172                         break;
1173
1174         /* If we are below the current region then a new region is required.
1175          * Subtle, allocate a new region at the position but make it zero
1176          * size such that we can guarantee to record the reservation. */
1177         if (&rg->link == head || t < rg->from) {
1178                 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
1179                 if (!nrg)
1180                         return -ENOMEM;
1181                 nrg->from = f;
1182                 nrg->to   = f;
1183                 INIT_LIST_HEAD(&nrg->link);
1184                 list_add(&nrg->link, rg->link.prev);
1185
1186                 return t - f;
1187         }
1188
1189         /* Round our left edge to the current segment if it encloses us. */
1190         if (f > rg->from)
1191                 f = rg->from;
1192         chg = t - f;
1193
1194         /* Check for and consume any regions we now overlap with. */
1195         list_for_each_entry(rg, rg->link.prev, link) {
1196                 if (&rg->link == head)
1197                         break;
1198                 if (rg->from > t)
1199                         return chg;
1200
1201                 /* We overlap with this area, if it extends futher than
1202                  * us then we must extend ourselves.  Account for its
1203                  * existing reservation. */
1204                 if (rg->to > t) {
1205                         chg += rg->to - t;
1206                         t = rg->to;
1207                 }
1208                 chg -= rg->to - rg->from;
1209         }
1210         return chg;
1211 }
1212
1213 static long region_truncate(struct list_head *head, long end)
1214 {
1215         struct file_region *rg, *trg;
1216         long chg = 0;
1217
1218         /* Locate the region we are either in or before. */
1219         list_for_each_entry(rg, head, link)
1220                 if (end <= rg->to)
1221                         break;
1222         if (&rg->link == head)
1223                 return 0;
1224
1225         /* If we are in the middle of a region then adjust it. */
1226         if (end > rg->from) {
1227                 chg = rg->to - end;
1228                 rg->to = end;
1229                 rg = list_entry(rg->link.next, typeof(*rg), link);
1230         }
1231
1232         /* Drop any remaining regions. */
1233         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
1234                 if (&rg->link == head)
1235                         break;
1236                 chg += rg->to - rg->from;
1237                 list_del(&rg->link);
1238                 kfree(rg);
1239         }
1240         return chg;
1241 }
1242
1243 static int hugetlb_acct_memory(long delta)
1244 {
1245         int ret = -ENOMEM;
1246
1247         spin_lock(&hugetlb_lock);
1248         /*
1249          * When cpuset is configured, it breaks the strict hugetlb page
1250          * reservation as the accounting is done on a global variable. Such
1251          * reservation is completely rubbish in the presence of cpuset because
1252          * the reservation is not checked against page availability for the
1253          * current cpuset. Application can still potentially OOM'ed by kernel
1254          * with lack of free htlb page in cpuset that the task is in.
1255          * Attempt to enforce strict accounting with cpuset is almost
1256          * impossible (or too ugly) because cpuset is too fluid that
1257          * task or memory node can be dynamically moved between cpusets.
1258          *
1259          * The change of semantics for shared hugetlb mapping with cpuset is
1260          * undesirable. However, in order to preserve some of the semantics,
1261          * we fall back to check against current free page availability as
1262          * a best attempt and hopefully to minimize the impact of changing
1263          * semantics that cpuset has.
1264          */
1265         if (delta > 0) {
1266                 if (gather_surplus_pages(delta) < 0)
1267                         goto out;
1268
1269                 if (delta > cpuset_mems_nr(free_huge_pages_node)) {
1270                         return_unused_surplus_pages(delta);
1271                         goto out;
1272                 }
1273         }
1274
1275         ret = 0;
1276         if (delta < 0)
1277                 return_unused_surplus_pages((unsigned long) -delta);
1278
1279 out:
1280         spin_unlock(&hugetlb_lock);
1281         return ret;
1282 }
1283
1284 int hugetlb_reserve_pages(struct inode *inode, long from, long to)
1285 {
1286         long ret, chg;
1287
1288         chg = region_chg(&inode->i_mapping->private_list, from, to);
1289         if (chg < 0)
1290                 return chg;
1291
1292         if (hugetlb_get_quota(inode->i_mapping, chg))
1293                 return -ENOSPC;
1294         ret = hugetlb_acct_memory(chg);
1295         if (ret < 0) {
1296                 hugetlb_put_quota(inode->i_mapping, chg);
1297                 return ret;
1298         }
1299         region_add(&inode->i_mapping->private_list, from, to);
1300         return 0;
1301 }
1302
1303 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
1304 {
1305         long chg = region_truncate(&inode->i_mapping->private_list, offset);
1306
1307         spin_lock(&inode->i_lock);
1308         inode->i_blocks -= BLOCKS_PER_HUGEPAGE * freed;
1309         spin_unlock(&inode->i_lock);
1310
1311         hugetlb_put_quota(inode->i_mapping, (chg - freed));
1312         hugetlb_acct_memory(-(chg - freed));
1313 }