[PATCH] mm: ZAP_BLOCK causes redundant work
[linux-2.6.git] / mm / memory.c
1 /*
2  *  linux/mm/memory.c
3  *
4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
5  */
6
7 /*
8  * demand-loading started 01.12.91 - seems it is high on the list of
9  * things wanted, and it should be easy to implement. - Linus
10  */
11
12 /*
13  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14  * pages started 02.12.91, seems to work. - Linus.
15  *
16  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17  * would have taken more than the 6M I have free, but it worked well as
18  * far as I could see.
19  *
20  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21  */
22
23 /*
24  * Real VM (paging to/from disk) started 18.12.91. Much more work and
25  * thought has to go into this. Oh, well..
26  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
27  *              Found it. Everything seems to work now.
28  * 20.12.91  -  Ok, making the swap-device changeable like the root.
29  */
30
31 /*
32  * 05.04.94  -  Multi-page memory management added for v1.1.
33  *              Idea by Alex Bligh (alex@cconcepts.co.uk)
34  *
35  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
36  *              (Gerhard.Wichert@pdb.siemens.de)
37  *
38  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39  */
40
41 #include <linux/kernel_stat.h>
42 #include <linux/mm.h>
43 #include <linux/hugetlb.h>
44 #include <linux/mman.h>
45 #include <linux/swap.h>
46 #include <linux/highmem.h>
47 #include <linux/pagemap.h>
48 #include <linux/rmap.h>
49 #include <linux/module.h>
50 #include <linux/init.h>
51
52 #include <asm/pgalloc.h>
53 #include <asm/uaccess.h>
54 #include <asm/tlb.h>
55 #include <asm/tlbflush.h>
56 #include <asm/pgtable.h>
57
58 #include <linux/swapops.h>
59 #include <linux/elf.h>
60
61 #ifndef CONFIG_NEED_MULTIPLE_NODES
62 /* use the per-pgdat data instead for discontigmem - mbligh */
63 unsigned long max_mapnr;
64 struct page *mem_map;
65
66 EXPORT_SYMBOL(max_mapnr);
67 EXPORT_SYMBOL(mem_map);
68 #endif
69
70 unsigned long num_physpages;
71 /*
72  * A number of key systems in x86 including ioremap() rely on the assumption
73  * that high_memory defines the upper bound on direct map memory, then end
74  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
75  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
76  * and ZONE_HIGHMEM.
77  */
78 void * high_memory;
79 unsigned long vmalloc_earlyreserve;
80
81 EXPORT_SYMBOL(num_physpages);
82 EXPORT_SYMBOL(high_memory);
83 EXPORT_SYMBOL(vmalloc_earlyreserve);
84
85 /*
86  * If a p?d_bad entry is found while walking page tables, report
87  * the error, before resetting entry to p?d_none.  Usually (but
88  * very seldom) called out from the p?d_none_or_clear_bad macros.
89  */
90
91 void pgd_clear_bad(pgd_t *pgd)
92 {
93         pgd_ERROR(*pgd);
94         pgd_clear(pgd);
95 }
96
97 void pud_clear_bad(pud_t *pud)
98 {
99         pud_ERROR(*pud);
100         pud_clear(pud);
101 }
102
103 void pmd_clear_bad(pmd_t *pmd)
104 {
105         pmd_ERROR(*pmd);
106         pmd_clear(pmd);
107 }
108
109 /*
110  * Note: this doesn't free the actual pages themselves. That
111  * has been handled earlier when unmapping all the memory regions.
112  */
113 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
114 {
115         struct page *page = pmd_page(*pmd);
116         pmd_clear(pmd);
117         pte_lock_deinit(page);
118         pte_free_tlb(tlb, page);
119         dec_page_state(nr_page_table_pages);
120         tlb->mm->nr_ptes--;
121 }
122
123 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
124                                 unsigned long addr, unsigned long end,
125                                 unsigned long floor, unsigned long ceiling)
126 {
127         pmd_t *pmd;
128         unsigned long next;
129         unsigned long start;
130
131         start = addr;
132         pmd = pmd_offset(pud, addr);
133         do {
134                 next = pmd_addr_end(addr, end);
135                 if (pmd_none_or_clear_bad(pmd))
136                         continue;
137                 free_pte_range(tlb, pmd);
138         } while (pmd++, addr = next, addr != end);
139
140         start &= PUD_MASK;
141         if (start < floor)
142                 return;
143         if (ceiling) {
144                 ceiling &= PUD_MASK;
145                 if (!ceiling)
146                         return;
147         }
148         if (end - 1 > ceiling - 1)
149                 return;
150
151         pmd = pmd_offset(pud, start);
152         pud_clear(pud);
153         pmd_free_tlb(tlb, pmd);
154 }
155
156 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
157                                 unsigned long addr, unsigned long end,
158                                 unsigned long floor, unsigned long ceiling)
159 {
160         pud_t *pud;
161         unsigned long next;
162         unsigned long start;
163
164         start = addr;
165         pud = pud_offset(pgd, addr);
166         do {
167                 next = pud_addr_end(addr, end);
168                 if (pud_none_or_clear_bad(pud))
169                         continue;
170                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
171         } while (pud++, addr = next, addr != end);
172
173         start &= PGDIR_MASK;
174         if (start < floor)
175                 return;
176         if (ceiling) {
177                 ceiling &= PGDIR_MASK;
178                 if (!ceiling)
179                         return;
180         }
181         if (end - 1 > ceiling - 1)
182                 return;
183
184         pud = pud_offset(pgd, start);
185         pgd_clear(pgd);
186         pud_free_tlb(tlb, pud);
187 }
188
189 /*
190  * This function frees user-level page tables of a process.
191  *
192  * Must be called with pagetable lock held.
193  */
194 void free_pgd_range(struct mmu_gather **tlb,
195                         unsigned long addr, unsigned long end,
196                         unsigned long floor, unsigned long ceiling)
197 {
198         pgd_t *pgd;
199         unsigned long next;
200         unsigned long start;
201
202         /*
203          * The next few lines have given us lots of grief...
204          *
205          * Why are we testing PMD* at this top level?  Because often
206          * there will be no work to do at all, and we'd prefer not to
207          * go all the way down to the bottom just to discover that.
208          *
209          * Why all these "- 1"s?  Because 0 represents both the bottom
210          * of the address space and the top of it (using -1 for the
211          * top wouldn't help much: the masks would do the wrong thing).
212          * The rule is that addr 0 and floor 0 refer to the bottom of
213          * the address space, but end 0 and ceiling 0 refer to the top
214          * Comparisons need to use "end - 1" and "ceiling - 1" (though
215          * that end 0 case should be mythical).
216          *
217          * Wherever addr is brought up or ceiling brought down, we must
218          * be careful to reject "the opposite 0" before it confuses the
219          * subsequent tests.  But what about where end is brought down
220          * by PMD_SIZE below? no, end can't go down to 0 there.
221          *
222          * Whereas we round start (addr) and ceiling down, by different
223          * masks at different levels, in order to test whether a table
224          * now has no other vmas using it, so can be freed, we don't
225          * bother to round floor or end up - the tests don't need that.
226          */
227
228         addr &= PMD_MASK;
229         if (addr < floor) {
230                 addr += PMD_SIZE;
231                 if (!addr)
232                         return;
233         }
234         if (ceiling) {
235                 ceiling &= PMD_MASK;
236                 if (!ceiling)
237                         return;
238         }
239         if (end - 1 > ceiling - 1)
240                 end -= PMD_SIZE;
241         if (addr > end - 1)
242                 return;
243
244         start = addr;
245         pgd = pgd_offset((*tlb)->mm, addr);
246         do {
247                 next = pgd_addr_end(addr, end);
248                 if (pgd_none_or_clear_bad(pgd))
249                         continue;
250                 free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
251         } while (pgd++, addr = next, addr != end);
252
253         if (!(*tlb)->fullmm)
254                 flush_tlb_pgtables((*tlb)->mm, start, end);
255 }
256
257 void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
258                 unsigned long floor, unsigned long ceiling)
259 {
260         while (vma) {
261                 struct vm_area_struct *next = vma->vm_next;
262                 unsigned long addr = vma->vm_start;
263
264                 /*
265                  * Hide vma from rmap and vmtruncate before freeing pgtables
266                  */
267                 anon_vma_unlink(vma);
268                 unlink_file_vma(vma);
269
270                 if (is_hugepage_only_range(vma->vm_mm, addr, HPAGE_SIZE)) {
271                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
272                                 floor, next? next->vm_start: ceiling);
273                 } else {
274                         /*
275                          * Optimization: gather nearby vmas into one call down
276                          */
277                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
278                           && !is_hugepage_only_range(vma->vm_mm, next->vm_start,
279                                                         HPAGE_SIZE)) {
280                                 vma = next;
281                                 next = vma->vm_next;
282                                 anon_vma_unlink(vma);
283                                 unlink_file_vma(vma);
284                         }
285                         free_pgd_range(tlb, addr, vma->vm_end,
286                                 floor, next? next->vm_start: ceiling);
287                 }
288                 vma = next;
289         }
290 }
291
292 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
293 {
294         struct page *new = pte_alloc_one(mm, address);
295         if (!new)
296                 return -ENOMEM;
297
298         pte_lock_init(new);
299         spin_lock(&mm->page_table_lock);
300         if (pmd_present(*pmd)) {        /* Another has populated it */
301                 pte_lock_deinit(new);
302                 pte_free(new);
303         } else {
304                 mm->nr_ptes++;
305                 inc_page_state(nr_page_table_pages);
306                 pmd_populate(mm, pmd, new);
307         }
308         spin_unlock(&mm->page_table_lock);
309         return 0;
310 }
311
312 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
313 {
314         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
315         if (!new)
316                 return -ENOMEM;
317
318         spin_lock(&init_mm.page_table_lock);
319         if (pmd_present(*pmd))          /* Another has populated it */
320                 pte_free_kernel(new);
321         else
322                 pmd_populate_kernel(&init_mm, pmd, new);
323         spin_unlock(&init_mm.page_table_lock);
324         return 0;
325 }
326
327 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss)
328 {
329         if (file_rss)
330                 add_mm_counter(mm, file_rss, file_rss);
331         if (anon_rss)
332                 add_mm_counter(mm, anon_rss, anon_rss);
333 }
334
335 /*
336  * This function is called to print an error when a pte in a
337  * !VM_RESERVED region is found pointing to an invalid pfn (which
338  * is an error.
339  *
340  * The calling function must still handle the error.
341  */
342 void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr)
343 {
344         printk(KERN_ERR "Bad pte = %08llx, process = %s, "
345                         "vm_flags = %lx, vaddr = %lx\n",
346                 (long long)pte_val(pte),
347                 (vma->vm_mm == current->mm ? current->comm : "???"),
348                 vma->vm_flags, vaddr);
349         dump_stack();
350 }
351
352 /*
353  * copy one vm_area from one task to the other. Assumes the page tables
354  * already present in the new task to be cleared in the whole range
355  * covered by this vma.
356  */
357
358 static inline void
359 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
360                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
361                 unsigned long addr, int *rss)
362 {
363         unsigned long vm_flags = vma->vm_flags;
364         pte_t pte = *src_pte;
365         struct page *page;
366         unsigned long pfn;
367
368         /* pte contains position in swap or file, so copy. */
369         if (unlikely(!pte_present(pte))) {
370                 if (!pte_file(pte)) {
371                         swap_duplicate(pte_to_swp_entry(pte));
372                         /* make sure dst_mm is on swapoff's mmlist. */
373                         if (unlikely(list_empty(&dst_mm->mmlist))) {
374                                 spin_lock(&mmlist_lock);
375                                 if (list_empty(&dst_mm->mmlist))
376                                         list_add(&dst_mm->mmlist,
377                                                  &src_mm->mmlist);
378                                 spin_unlock(&mmlist_lock);
379                         }
380                 }
381                 goto out_set_pte;
382         }
383
384         /* If the region is VM_RESERVED, the mapping is not
385          * mapped via rmap - duplicate the pte as is.
386          */
387         if (vm_flags & VM_RESERVED)
388                 goto out_set_pte;
389
390         pfn = pte_pfn(pte);
391         /* If the pte points outside of valid memory but
392          * the region is not VM_RESERVED, we have a problem.
393          */
394         if (unlikely(!pfn_valid(pfn))) {
395                 print_bad_pte(vma, pte, addr);
396                 goto out_set_pte; /* try to do something sane */
397         }
398
399         page = pfn_to_page(pfn);
400
401         /*
402          * If it's a COW mapping, write protect it both
403          * in the parent and the child
404          */
405         if ((vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE) {
406                 ptep_set_wrprotect(src_mm, addr, src_pte);
407                 pte = *src_pte;
408         }
409
410         /*
411          * If it's a shared mapping, mark it clean in
412          * the child
413          */
414         if (vm_flags & VM_SHARED)
415                 pte = pte_mkclean(pte);
416         pte = pte_mkold(pte);
417         get_page(page);
418         page_dup_rmap(page);
419         rss[!!PageAnon(page)]++;
420
421 out_set_pte:
422         set_pte_at(dst_mm, addr, dst_pte, pte);
423 }
424
425 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
426                 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
427                 unsigned long addr, unsigned long end)
428 {
429         pte_t *src_pte, *dst_pte;
430         spinlock_t *src_ptl, *dst_ptl;
431         int progress = 0;
432         int rss[2];
433
434 again:
435         rss[1] = rss[0] = 0;
436         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
437         if (!dst_pte)
438                 return -ENOMEM;
439         src_pte = pte_offset_map_nested(src_pmd, addr);
440         src_ptl = pte_lockptr(src_mm, src_pmd);
441         spin_lock(src_ptl);
442
443         do {
444                 /*
445                  * We are holding two locks at this point - either of them
446                  * could generate latencies in another task on another CPU.
447                  */
448                 if (progress >= 32) {
449                         progress = 0;
450                         if (need_resched() ||
451                             need_lockbreak(src_ptl) ||
452                             need_lockbreak(dst_ptl))
453                                 break;
454                 }
455                 if (pte_none(*src_pte)) {
456                         progress++;
457                         continue;
458                 }
459                 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss);
460                 progress += 8;
461         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
462
463         spin_unlock(src_ptl);
464         pte_unmap_nested(src_pte - 1);
465         add_mm_rss(dst_mm, rss[0], rss[1]);
466         pte_unmap_unlock(dst_pte - 1, dst_ptl);
467         cond_resched();
468         if (addr != end)
469                 goto again;
470         return 0;
471 }
472
473 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
474                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
475                 unsigned long addr, unsigned long end)
476 {
477         pmd_t *src_pmd, *dst_pmd;
478         unsigned long next;
479
480         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
481         if (!dst_pmd)
482                 return -ENOMEM;
483         src_pmd = pmd_offset(src_pud, addr);
484         do {
485                 next = pmd_addr_end(addr, end);
486                 if (pmd_none_or_clear_bad(src_pmd))
487                         continue;
488                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
489                                                 vma, addr, next))
490                         return -ENOMEM;
491         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
492         return 0;
493 }
494
495 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
496                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
497                 unsigned long addr, unsigned long end)
498 {
499         pud_t *src_pud, *dst_pud;
500         unsigned long next;
501
502         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
503         if (!dst_pud)
504                 return -ENOMEM;
505         src_pud = pud_offset(src_pgd, addr);
506         do {
507                 next = pud_addr_end(addr, end);
508                 if (pud_none_or_clear_bad(src_pud))
509                         continue;
510                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
511                                                 vma, addr, next))
512                         return -ENOMEM;
513         } while (dst_pud++, src_pud++, addr = next, addr != end);
514         return 0;
515 }
516
517 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
518                 struct vm_area_struct *vma)
519 {
520         pgd_t *src_pgd, *dst_pgd;
521         unsigned long next;
522         unsigned long addr = vma->vm_start;
523         unsigned long end = vma->vm_end;
524
525         /*
526          * Don't copy ptes where a page fault will fill them correctly.
527          * Fork becomes much lighter when there are big shared or private
528          * readonly mappings. The tradeoff is that copy_page_range is more
529          * efficient than faulting.
530          */
531         if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_RESERVED))) {
532                 if (!vma->anon_vma)
533                         return 0;
534         }
535
536         if (is_vm_hugetlb_page(vma))
537                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
538
539         dst_pgd = pgd_offset(dst_mm, addr);
540         src_pgd = pgd_offset(src_mm, addr);
541         do {
542                 next = pgd_addr_end(addr, end);
543                 if (pgd_none_or_clear_bad(src_pgd))
544                         continue;
545                 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
546                                                 vma, addr, next))
547                         return -ENOMEM;
548         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
549         return 0;
550 }
551
552 static unsigned long zap_pte_range(struct mmu_gather *tlb,
553                                 struct vm_area_struct *vma, pmd_t *pmd,
554                                 unsigned long addr, unsigned long end,
555                                 long *zap_work, struct zap_details *details)
556 {
557         struct mm_struct *mm = tlb->mm;
558         pte_t *pte;
559         spinlock_t *ptl;
560         int file_rss = 0;
561         int anon_rss = 0;
562
563         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
564         do {
565                 pte_t ptent = *pte;
566                 if (pte_none(ptent)) {
567                         (*zap_work)--;
568                         continue;
569                 }
570                 if (pte_present(ptent)) {
571                         struct page *page = NULL;
572
573                         (*zap_work) -= PAGE_SIZE;
574
575                         if (!(vma->vm_flags & VM_RESERVED)) {
576                                 unsigned long pfn = pte_pfn(ptent);
577                                 if (unlikely(!pfn_valid(pfn)))
578                                         print_bad_pte(vma, ptent, addr);
579                                 else
580                                         page = pfn_to_page(pfn);
581                         }
582                         if (unlikely(details) && page) {
583                                 /*
584                                  * unmap_shared_mapping_pages() wants to
585                                  * invalidate cache without truncating:
586                                  * unmap shared but keep private pages.
587                                  */
588                                 if (details->check_mapping &&
589                                     details->check_mapping != page->mapping)
590                                         continue;
591                                 /*
592                                  * Each page->index must be checked when
593                                  * invalidating or truncating nonlinear.
594                                  */
595                                 if (details->nonlinear_vma &&
596                                     (page->index < details->first_index ||
597                                      page->index > details->last_index))
598                                         continue;
599                         }
600                         ptent = ptep_get_and_clear_full(mm, addr, pte,
601                                                         tlb->fullmm);
602                         tlb_remove_tlb_entry(tlb, pte, addr);
603                         if (unlikely(!page))
604                                 continue;
605                         if (unlikely(details) && details->nonlinear_vma
606                             && linear_page_index(details->nonlinear_vma,
607                                                 addr) != page->index)
608                                 set_pte_at(mm, addr, pte,
609                                            pgoff_to_pte(page->index));
610                         if (PageAnon(page))
611                                 anon_rss--;
612                         else {
613                                 if (pte_dirty(ptent))
614                                         set_page_dirty(page);
615                                 if (pte_young(ptent))
616                                         mark_page_accessed(page);
617                                 file_rss--;
618                         }
619                         page_remove_rmap(page);
620                         tlb_remove_page(tlb, page);
621                         continue;
622                 }
623                 /*
624                  * If details->check_mapping, we leave swap entries;
625                  * if details->nonlinear_vma, we leave file entries.
626                  */
627                 if (unlikely(details))
628                         continue;
629                 if (!pte_file(ptent))
630                         free_swap_and_cache(pte_to_swp_entry(ptent));
631                 pte_clear_full(mm, addr, pte, tlb->fullmm);
632         } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
633
634         add_mm_rss(mm, file_rss, anon_rss);
635         pte_unmap_unlock(pte - 1, ptl);
636
637         return addr;
638 }
639
640 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
641                                 struct vm_area_struct *vma, pud_t *pud,
642                                 unsigned long addr, unsigned long end,
643                                 long *zap_work, struct zap_details *details)
644 {
645         pmd_t *pmd;
646         unsigned long next;
647
648         pmd = pmd_offset(pud, addr);
649         do {
650                 next = pmd_addr_end(addr, end);
651                 if (pmd_none_or_clear_bad(pmd)) {
652                         (*zap_work)--;
653                         continue;
654                 }
655                 next = zap_pte_range(tlb, vma, pmd, addr, next,
656                                                 zap_work, details);
657         } while (pmd++, addr = next, (addr != end && *zap_work > 0));
658
659         return addr;
660 }
661
662 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
663                                 struct vm_area_struct *vma, pgd_t *pgd,
664                                 unsigned long addr, unsigned long end,
665                                 long *zap_work, struct zap_details *details)
666 {
667         pud_t *pud;
668         unsigned long next;
669
670         pud = pud_offset(pgd, addr);
671         do {
672                 next = pud_addr_end(addr, end);
673                 if (pud_none_or_clear_bad(pud)) {
674                         (*zap_work)--;
675                         continue;
676                 }
677                 next = zap_pmd_range(tlb, vma, pud, addr, next,
678                                                 zap_work, details);
679         } while (pud++, addr = next, (addr != end && *zap_work > 0));
680
681         return addr;
682 }
683
684 static unsigned long unmap_page_range(struct mmu_gather *tlb,
685                                 struct vm_area_struct *vma,
686                                 unsigned long addr, unsigned long end,
687                                 long *zap_work, struct zap_details *details)
688 {
689         pgd_t *pgd;
690         unsigned long next;
691
692         if (details && !details->check_mapping && !details->nonlinear_vma)
693                 details = NULL;
694
695         BUG_ON(addr >= end);
696         tlb_start_vma(tlb, vma);
697         pgd = pgd_offset(vma->vm_mm, addr);
698         do {
699                 next = pgd_addr_end(addr, end);
700                 if (pgd_none_or_clear_bad(pgd)) {
701                         (*zap_work)--;
702                         continue;
703                 }
704                 next = zap_pud_range(tlb, vma, pgd, addr, next,
705                                                 zap_work, details);
706         } while (pgd++, addr = next, (addr != end && *zap_work > 0));
707         tlb_end_vma(tlb, vma);
708
709         return addr;
710 }
711
712 #ifdef CONFIG_PREEMPT
713 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
714 #else
715 /* No preempt: go for improved straight-line efficiency */
716 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
717 #endif
718
719 /**
720  * unmap_vmas - unmap a range of memory covered by a list of vma's
721  * @tlbp: address of the caller's struct mmu_gather
722  * @vma: the starting vma
723  * @start_addr: virtual address at which to start unmapping
724  * @end_addr: virtual address at which to end unmapping
725  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
726  * @details: details of nonlinear truncation or shared cache invalidation
727  *
728  * Returns the end address of the unmapping (restart addr if interrupted).
729  *
730  * Unmap all pages in the vma list.
731  *
732  * We aim to not hold locks for too long (for scheduling latency reasons).
733  * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
734  * return the ending mmu_gather to the caller.
735  *
736  * Only addresses between `start' and `end' will be unmapped.
737  *
738  * The VMA list must be sorted in ascending virtual address order.
739  *
740  * unmap_vmas() assumes that the caller will flush the whole unmapped address
741  * range after unmap_vmas() returns.  So the only responsibility here is to
742  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
743  * drops the lock and schedules.
744  */
745 unsigned long unmap_vmas(struct mmu_gather **tlbp,
746                 struct vm_area_struct *vma, unsigned long start_addr,
747                 unsigned long end_addr, unsigned long *nr_accounted,
748                 struct zap_details *details)
749 {
750         long zap_work = ZAP_BLOCK_SIZE;
751         unsigned long tlb_start = 0;    /* For tlb_finish_mmu */
752         int tlb_start_valid = 0;
753         unsigned long start = start_addr;
754         spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
755         int fullmm = (*tlbp)->fullmm;
756
757         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
758                 unsigned long end;
759
760                 start = max(vma->vm_start, start_addr);
761                 if (start >= vma->vm_end)
762                         continue;
763                 end = min(vma->vm_end, end_addr);
764                 if (end <= vma->vm_start)
765                         continue;
766
767                 if (vma->vm_flags & VM_ACCOUNT)
768                         *nr_accounted += (end - start) >> PAGE_SHIFT;
769
770                 while (start != end) {
771                         if (!tlb_start_valid) {
772                                 tlb_start = start;
773                                 tlb_start_valid = 1;
774                         }
775
776                         if (unlikely(is_vm_hugetlb_page(vma))) {
777                                 unmap_hugepage_range(vma, start, end);
778                                 zap_work -= (end - start) /
779                                                 (HPAGE_SIZE / PAGE_SIZE);
780                                 start = end;
781                         } else
782                                 start = unmap_page_range(*tlbp, vma,
783                                                 start, end, &zap_work, details);
784
785                         if (zap_work > 0) {
786                                 BUG_ON(start != end);
787                                 break;
788                         }
789
790                         tlb_finish_mmu(*tlbp, tlb_start, start);
791
792                         if (need_resched() ||
793                                 (i_mmap_lock && need_lockbreak(i_mmap_lock))) {
794                                 if (i_mmap_lock) {
795                                         *tlbp = NULL;
796                                         goto out;
797                                 }
798                                 cond_resched();
799                         }
800
801                         *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
802                         tlb_start_valid = 0;
803                         zap_work = ZAP_BLOCK_SIZE;
804                 }
805         }
806 out:
807         return start;   /* which is now the end (or restart) address */
808 }
809
810 /**
811  * zap_page_range - remove user pages in a given range
812  * @vma: vm_area_struct holding the applicable pages
813  * @address: starting address of pages to zap
814  * @size: number of bytes to zap
815  * @details: details of nonlinear truncation or shared cache invalidation
816  */
817 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
818                 unsigned long size, struct zap_details *details)
819 {
820         struct mm_struct *mm = vma->vm_mm;
821         struct mmu_gather *tlb;
822         unsigned long end = address + size;
823         unsigned long nr_accounted = 0;
824
825         lru_add_drain();
826         tlb = tlb_gather_mmu(mm, 0);
827         update_hiwater_rss(mm);
828         end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
829         if (tlb)
830                 tlb_finish_mmu(tlb, address, end);
831         return end;
832 }
833
834 /*
835  * Do a quick page-table lookup for a single page.
836  */
837 struct page *follow_page(struct mm_struct *mm, unsigned long address,
838                         unsigned int flags)
839 {
840         pgd_t *pgd;
841         pud_t *pud;
842         pmd_t *pmd;
843         pte_t *ptep, pte;
844         spinlock_t *ptl;
845         unsigned long pfn;
846         struct page *page;
847
848         page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
849         if (!IS_ERR(page)) {
850                 BUG_ON(flags & FOLL_GET);
851                 goto out;
852         }
853
854         page = NULL;
855         pgd = pgd_offset(mm, address);
856         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
857                 goto no_page_table;
858
859         pud = pud_offset(pgd, address);
860         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
861                 goto no_page_table;
862         
863         pmd = pmd_offset(pud, address);
864         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
865                 goto no_page_table;
866
867         if (pmd_huge(*pmd)) {
868                 BUG_ON(flags & FOLL_GET);
869                 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
870                 goto out;
871         }
872
873         ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
874         if (!ptep)
875                 goto out;
876
877         pte = *ptep;
878         if (!pte_present(pte))
879                 goto unlock;
880         if ((flags & FOLL_WRITE) && !pte_write(pte))
881                 goto unlock;
882         pfn = pte_pfn(pte);
883         if (!pfn_valid(pfn))
884                 goto unlock;
885
886         page = pfn_to_page(pfn);
887         if (flags & FOLL_GET)
888                 get_page(page);
889         if (flags & FOLL_TOUCH) {
890                 if ((flags & FOLL_WRITE) &&
891                     !pte_dirty(pte) && !PageDirty(page))
892                         set_page_dirty(page);
893                 mark_page_accessed(page);
894         }
895 unlock:
896         pte_unmap_unlock(ptep, ptl);
897 out:
898         return page;
899
900 no_page_table:
901         /*
902          * When core dumping an enormous anonymous area that nobody
903          * has touched so far, we don't want to allocate page tables.
904          */
905         if (flags & FOLL_ANON) {
906                 page = ZERO_PAGE(address);
907                 if (flags & FOLL_GET)
908                         get_page(page);
909                 BUG_ON(flags & FOLL_WRITE);
910         }
911         return page;
912 }
913
914 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
915                 unsigned long start, int len, int write, int force,
916                 struct page **pages, struct vm_area_struct **vmas)
917 {
918         int i;
919         unsigned int vm_flags;
920
921         /* 
922          * Require read or write permissions.
923          * If 'force' is set, we only require the "MAY" flags.
924          */
925         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
926         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
927         i = 0;
928
929         do {
930                 struct vm_area_struct *vma;
931                 unsigned int foll_flags;
932
933                 vma = find_extend_vma(mm, start);
934                 if (!vma && in_gate_area(tsk, start)) {
935                         unsigned long pg = start & PAGE_MASK;
936                         struct vm_area_struct *gate_vma = get_gate_vma(tsk);
937                         pgd_t *pgd;
938                         pud_t *pud;
939                         pmd_t *pmd;
940                         pte_t *pte;
941                         if (write) /* user gate pages are read-only */
942                                 return i ? : -EFAULT;
943                         if (pg > TASK_SIZE)
944                                 pgd = pgd_offset_k(pg);
945                         else
946                                 pgd = pgd_offset_gate(mm, pg);
947                         BUG_ON(pgd_none(*pgd));
948                         pud = pud_offset(pgd, pg);
949                         BUG_ON(pud_none(*pud));
950                         pmd = pmd_offset(pud, pg);
951                         if (pmd_none(*pmd))
952                                 return i ? : -EFAULT;
953                         pte = pte_offset_map(pmd, pg);
954                         if (pte_none(*pte)) {
955                                 pte_unmap(pte);
956                                 return i ? : -EFAULT;
957                         }
958                         if (pages) {
959                                 pages[i] = pte_page(*pte);
960                                 get_page(pages[i]);
961                         }
962                         pte_unmap(pte);
963                         if (vmas)
964                                 vmas[i] = gate_vma;
965                         i++;
966                         start += PAGE_SIZE;
967                         len--;
968                         continue;
969                 }
970
971                 if (!vma || (vma->vm_flags & (VM_IO | VM_RESERVED))
972                                 || !(vm_flags & vma->vm_flags))
973                         return i ? : -EFAULT;
974
975                 if (is_vm_hugetlb_page(vma)) {
976                         i = follow_hugetlb_page(mm, vma, pages, vmas,
977                                                 &start, &len, i);
978                         continue;
979                 }
980
981                 foll_flags = FOLL_TOUCH;
982                 if (pages)
983                         foll_flags |= FOLL_GET;
984                 if (!write && !(vma->vm_flags & VM_LOCKED) &&
985                     (!vma->vm_ops || !vma->vm_ops->nopage))
986                         foll_flags |= FOLL_ANON;
987
988                 do {
989                         struct page *page;
990
991                         if (write)
992                                 foll_flags |= FOLL_WRITE;
993
994                         cond_resched();
995                         while (!(page = follow_page(mm, start, foll_flags))) {
996                                 int ret;
997                                 ret = __handle_mm_fault(mm, vma, start,
998                                                 foll_flags & FOLL_WRITE);
999                                 /*
1000                                  * The VM_FAULT_WRITE bit tells us that do_wp_page has
1001                                  * broken COW when necessary, even if maybe_mkwrite
1002                                  * decided not to set pte_write. We can thus safely do
1003                                  * subsequent page lookups as if they were reads.
1004                                  */
1005                                 if (ret & VM_FAULT_WRITE)
1006                                         foll_flags &= ~FOLL_WRITE;
1007                                 
1008                                 switch (ret & ~VM_FAULT_WRITE) {
1009                                 case VM_FAULT_MINOR:
1010                                         tsk->min_flt++;
1011                                         break;
1012                                 case VM_FAULT_MAJOR:
1013                                         tsk->maj_flt++;
1014                                         break;
1015                                 case VM_FAULT_SIGBUS:
1016                                         return i ? i : -EFAULT;
1017                                 case VM_FAULT_OOM:
1018                                         return i ? i : -ENOMEM;
1019                                 default:
1020                                         BUG();
1021                                 }
1022                         }
1023                         if (pages) {
1024                                 pages[i] = page;
1025                                 flush_dcache_page(page);
1026                         }
1027                         if (vmas)
1028                                 vmas[i] = vma;
1029                         i++;
1030                         start += PAGE_SIZE;
1031                         len--;
1032                 } while (len && start < vma->vm_end);
1033         } while (len);
1034         return i;
1035 }
1036 EXPORT_SYMBOL(get_user_pages);
1037
1038 static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1039                         unsigned long addr, unsigned long end, pgprot_t prot)
1040 {
1041         pte_t *pte;
1042         spinlock_t *ptl;
1043
1044         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1045         if (!pte)
1046                 return -ENOMEM;
1047         do {
1048                 struct page *page = ZERO_PAGE(addr);
1049                 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot));
1050                 page_cache_get(page);
1051                 page_add_file_rmap(page);
1052                 inc_mm_counter(mm, file_rss);
1053                 BUG_ON(!pte_none(*pte));
1054                 set_pte_at(mm, addr, pte, zero_pte);
1055         } while (pte++, addr += PAGE_SIZE, addr != end);
1056         pte_unmap_unlock(pte - 1, ptl);
1057         return 0;
1058 }
1059
1060 static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
1061                         unsigned long addr, unsigned long end, pgprot_t prot)
1062 {
1063         pmd_t *pmd;
1064         unsigned long next;
1065
1066         pmd = pmd_alloc(mm, pud, addr);
1067         if (!pmd)
1068                 return -ENOMEM;
1069         do {
1070                 next = pmd_addr_end(addr, end);
1071                 if (zeromap_pte_range(mm, pmd, addr, next, prot))
1072                         return -ENOMEM;
1073         } while (pmd++, addr = next, addr != end);
1074         return 0;
1075 }
1076
1077 static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1078                         unsigned long addr, unsigned long end, pgprot_t prot)
1079 {
1080         pud_t *pud;
1081         unsigned long next;
1082
1083         pud = pud_alloc(mm, pgd, addr);
1084         if (!pud)
1085                 return -ENOMEM;
1086         do {
1087                 next = pud_addr_end(addr, end);
1088                 if (zeromap_pmd_range(mm, pud, addr, next, prot))
1089                         return -ENOMEM;
1090         } while (pud++, addr = next, addr != end);
1091         return 0;
1092 }
1093
1094 int zeromap_page_range(struct vm_area_struct *vma,
1095                         unsigned long addr, unsigned long size, pgprot_t prot)
1096 {
1097         pgd_t *pgd;
1098         unsigned long next;
1099         unsigned long end = addr + size;
1100         struct mm_struct *mm = vma->vm_mm;
1101         int err;
1102
1103         BUG_ON(addr >= end);
1104         pgd = pgd_offset(mm, addr);
1105         flush_cache_range(vma, addr, end);
1106         do {
1107                 next = pgd_addr_end(addr, end);
1108                 err = zeromap_pud_range(mm, pgd, addr, next, prot);
1109                 if (err)
1110                         break;
1111         } while (pgd++, addr = next, addr != end);
1112         return err;
1113 }
1114
1115 /*
1116  * maps a range of physical memory into the requested pages. the old
1117  * mappings are removed. any references to nonexistent pages results
1118  * in null mappings (currently treated as "copy-on-access")
1119  */
1120 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1121                         unsigned long addr, unsigned long end,
1122                         unsigned long pfn, pgprot_t prot)
1123 {
1124         pte_t *pte;
1125         spinlock_t *ptl;
1126
1127         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1128         if (!pte)
1129                 return -ENOMEM;
1130         do {
1131                 BUG_ON(!pte_none(*pte));
1132                 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
1133                 pfn++;
1134         } while (pte++, addr += PAGE_SIZE, addr != end);
1135         pte_unmap_unlock(pte - 1, ptl);
1136         return 0;
1137 }
1138
1139 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1140                         unsigned long addr, unsigned long end,
1141                         unsigned long pfn, pgprot_t prot)
1142 {
1143         pmd_t *pmd;
1144         unsigned long next;
1145
1146         pfn -= addr >> PAGE_SHIFT;
1147         pmd = pmd_alloc(mm, pud, addr);
1148         if (!pmd)
1149                 return -ENOMEM;
1150         do {
1151                 next = pmd_addr_end(addr, end);
1152                 if (remap_pte_range(mm, pmd, addr, next,
1153                                 pfn + (addr >> PAGE_SHIFT), prot))
1154                         return -ENOMEM;
1155         } while (pmd++, addr = next, addr != end);
1156         return 0;
1157 }
1158
1159 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1160                         unsigned long addr, unsigned long end,
1161                         unsigned long pfn, pgprot_t prot)
1162 {
1163         pud_t *pud;
1164         unsigned long next;
1165
1166         pfn -= addr >> PAGE_SHIFT;
1167         pud = pud_alloc(mm, pgd, addr);
1168         if (!pud)
1169                 return -ENOMEM;
1170         do {
1171                 next = pud_addr_end(addr, end);
1172                 if (remap_pmd_range(mm, pud, addr, next,
1173                                 pfn + (addr >> PAGE_SHIFT), prot))
1174                         return -ENOMEM;
1175         } while (pud++, addr = next, addr != end);
1176         return 0;
1177 }
1178
1179 /*  Note: this is only safe if the mm semaphore is held when called. */
1180 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1181                     unsigned long pfn, unsigned long size, pgprot_t prot)
1182 {
1183         pgd_t *pgd;
1184         unsigned long next;
1185         unsigned long end = addr + PAGE_ALIGN(size);
1186         struct mm_struct *mm = vma->vm_mm;
1187         int err;
1188
1189         /*
1190          * Physically remapped pages are special. Tell the
1191          * rest of the world about it:
1192          *   VM_IO tells people not to look at these pages
1193          *      (accesses can have side effects).
1194          *   VM_RESERVED tells the core MM not to "manage" these pages
1195          *      (e.g. refcount, mapcount, try to swap them out).
1196          */
1197         vma->vm_flags |= VM_IO | VM_RESERVED;
1198
1199         BUG_ON(addr >= end);
1200         pfn -= addr >> PAGE_SHIFT;
1201         pgd = pgd_offset(mm, addr);
1202         flush_cache_range(vma, addr, end);
1203         do {
1204                 next = pgd_addr_end(addr, end);
1205                 err = remap_pud_range(mm, pgd, addr, next,
1206                                 pfn + (addr >> PAGE_SHIFT), prot);
1207                 if (err)
1208                         break;
1209         } while (pgd++, addr = next, addr != end);
1210         return err;
1211 }
1212 EXPORT_SYMBOL(remap_pfn_range);
1213
1214 /*
1215  * handle_pte_fault chooses page fault handler according to an entry
1216  * which was read non-atomically.  Before making any commitment, on
1217  * those architectures or configurations (e.g. i386 with PAE) which
1218  * might give a mix of unmatched parts, do_swap_page and do_file_page
1219  * must check under lock before unmapping the pte and proceeding
1220  * (but do_wp_page is only called after already making such a check;
1221  * and do_anonymous_page and do_no_page can safely check later on).
1222  */
1223 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
1224                                 pte_t *page_table, pte_t orig_pte)
1225 {
1226         int same = 1;
1227 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
1228         if (sizeof(pte_t) > sizeof(unsigned long)) {
1229                 spinlock_t *ptl = pte_lockptr(mm, pmd);
1230                 spin_lock(ptl);
1231                 same = pte_same(*page_table, orig_pte);
1232                 spin_unlock(ptl);
1233         }
1234 #endif
1235         pte_unmap(page_table);
1236         return same;
1237 }
1238
1239 /*
1240  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
1241  * servicing faults for write access.  In the normal case, do always want
1242  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
1243  * that do not have writing enabled, when used by access_process_vm.
1244  */
1245 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1246 {
1247         if (likely(vma->vm_flags & VM_WRITE))
1248                 pte = pte_mkwrite(pte);
1249         return pte;
1250 }
1251
1252 /*
1253  * This routine handles present pages, when users try to write
1254  * to a shared page. It is done by copying the page to a new address
1255  * and decrementing the shared-page counter for the old page.
1256  *
1257  * Note that this routine assumes that the protection checks have been
1258  * done by the caller (the low-level page fault routine in most cases).
1259  * Thus we can safely just mark it writable once we've done any necessary
1260  * COW.
1261  *
1262  * We also mark the page dirty at this point even though the page will
1263  * change only once the write actually happens. This avoids a few races,
1264  * and potentially makes it more efficient.
1265  *
1266  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1267  * but allow concurrent faults), with pte both mapped and locked.
1268  * We return with mmap_sem still held, but pte unmapped and unlocked.
1269  */
1270 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
1271                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1272                 spinlock_t *ptl, pte_t orig_pte)
1273 {
1274         struct page *old_page, *new_page;
1275         unsigned long pfn = pte_pfn(orig_pte);
1276         pte_t entry;
1277         int ret = VM_FAULT_MINOR;
1278
1279         BUG_ON(vma->vm_flags & VM_RESERVED);
1280
1281         if (unlikely(!pfn_valid(pfn))) {
1282                 /*
1283                  * Page table corrupted: show pte and kill process.
1284                  */
1285                 print_bad_pte(vma, orig_pte, address);
1286                 ret = VM_FAULT_OOM;
1287                 goto unlock;
1288         }
1289         old_page = pfn_to_page(pfn);
1290
1291         if (PageAnon(old_page) && !TestSetPageLocked(old_page)) {
1292                 int reuse = can_share_swap_page(old_page);
1293                 unlock_page(old_page);
1294                 if (reuse) {
1295                         flush_cache_page(vma, address, pfn);
1296                         entry = pte_mkyoung(orig_pte);
1297                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1298                         ptep_set_access_flags(vma, address, page_table, entry, 1);
1299                         update_mmu_cache(vma, address, entry);
1300                         lazy_mmu_prot_update(entry);
1301                         ret |= VM_FAULT_WRITE;
1302                         goto unlock;
1303                 }
1304         }
1305
1306         /*
1307          * Ok, we need to copy. Oh, well..
1308          */
1309         page_cache_get(old_page);
1310         pte_unmap_unlock(page_table, ptl);
1311
1312         if (unlikely(anon_vma_prepare(vma)))
1313                 goto oom;
1314         if (old_page == ZERO_PAGE(address)) {
1315                 new_page = alloc_zeroed_user_highpage(vma, address);
1316                 if (!new_page)
1317                         goto oom;
1318         } else {
1319                 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1320                 if (!new_page)
1321                         goto oom;
1322                 copy_user_highpage(new_page, old_page, address);
1323         }
1324
1325         /*
1326          * Re-check the pte - we dropped the lock
1327          */
1328         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1329         if (likely(pte_same(*page_table, orig_pte))) {
1330                 page_remove_rmap(old_page);
1331                 if (!PageAnon(old_page)) {
1332                         inc_mm_counter(mm, anon_rss);
1333                         dec_mm_counter(mm, file_rss);
1334                 }
1335                 flush_cache_page(vma, address, pfn);
1336                 entry = mk_pte(new_page, vma->vm_page_prot);
1337                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1338                 ptep_establish(vma, address, page_table, entry);
1339                 update_mmu_cache(vma, address, entry);
1340                 lazy_mmu_prot_update(entry);
1341                 lru_cache_add_active(new_page);
1342                 page_add_anon_rmap(new_page, vma, address);
1343
1344                 /* Free the old page.. */
1345                 new_page = old_page;
1346                 ret |= VM_FAULT_WRITE;
1347         }
1348         page_cache_release(new_page);
1349         page_cache_release(old_page);
1350 unlock:
1351         pte_unmap_unlock(page_table, ptl);
1352         return ret;
1353 oom:
1354         page_cache_release(old_page);
1355         return VM_FAULT_OOM;
1356 }
1357
1358 /*
1359  * Helper functions for unmap_mapping_range().
1360  *
1361  * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1362  *
1363  * We have to restart searching the prio_tree whenever we drop the lock,
1364  * since the iterator is only valid while the lock is held, and anyway
1365  * a later vma might be split and reinserted earlier while lock dropped.
1366  *
1367  * The list of nonlinear vmas could be handled more efficiently, using
1368  * a placeholder, but handle it in the same way until a need is shown.
1369  * It is important to search the prio_tree before nonlinear list: a vma
1370  * may become nonlinear and be shifted from prio_tree to nonlinear list
1371  * while the lock is dropped; but never shifted from list to prio_tree.
1372  *
1373  * In order to make forward progress despite restarting the search,
1374  * vm_truncate_count is used to mark a vma as now dealt with, so we can
1375  * quickly skip it next time around.  Since the prio_tree search only
1376  * shows us those vmas affected by unmapping the range in question, we
1377  * can't efficiently keep all vmas in step with mapping->truncate_count:
1378  * so instead reset them all whenever it wraps back to 0 (then go to 1).
1379  * mapping->truncate_count and vma->vm_truncate_count are protected by
1380  * i_mmap_lock.
1381  *
1382  * In order to make forward progress despite repeatedly restarting some
1383  * large vma, note the restart_addr from unmap_vmas when it breaks out:
1384  * and restart from that address when we reach that vma again.  It might
1385  * have been split or merged, shrunk or extended, but never shifted: so
1386  * restart_addr remains valid so long as it remains in the vma's range.
1387  * unmap_mapping_range forces truncate_count to leap over page-aligned
1388  * values so we can save vma's restart_addr in its truncate_count field.
1389  */
1390 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1391
1392 static void reset_vma_truncate_counts(struct address_space *mapping)
1393 {
1394         struct vm_area_struct *vma;
1395         struct prio_tree_iter iter;
1396
1397         vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1398                 vma->vm_truncate_count = 0;
1399         list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1400                 vma->vm_truncate_count = 0;
1401 }
1402
1403 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1404                 unsigned long start_addr, unsigned long end_addr,
1405                 struct zap_details *details)
1406 {
1407         unsigned long restart_addr;
1408         int need_break;
1409
1410 again:
1411         restart_addr = vma->vm_truncate_count;
1412         if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1413                 start_addr = restart_addr;
1414                 if (start_addr >= end_addr) {
1415                         /* Top of vma has been split off since last time */
1416                         vma->vm_truncate_count = details->truncate_count;
1417                         return 0;
1418                 }
1419         }
1420
1421         restart_addr = zap_page_range(vma, start_addr,
1422                                         end_addr - start_addr, details);
1423         need_break = need_resched() ||
1424                         need_lockbreak(details->i_mmap_lock);
1425
1426         if (restart_addr >= end_addr) {
1427                 /* We have now completed this vma: mark it so */
1428                 vma->vm_truncate_count = details->truncate_count;
1429                 if (!need_break)
1430                         return 0;
1431         } else {
1432                 /* Note restart_addr in vma's truncate_count field */
1433                 vma->vm_truncate_count = restart_addr;
1434                 if (!need_break)
1435                         goto again;
1436         }
1437
1438         spin_unlock(details->i_mmap_lock);
1439         cond_resched();
1440         spin_lock(details->i_mmap_lock);
1441         return -EINTR;
1442 }
1443
1444 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1445                                             struct zap_details *details)
1446 {
1447         struct vm_area_struct *vma;
1448         struct prio_tree_iter iter;
1449         pgoff_t vba, vea, zba, zea;
1450
1451 restart:
1452         vma_prio_tree_foreach(vma, &iter, root,
1453                         details->first_index, details->last_index) {
1454                 /* Skip quickly over those we have already dealt with */
1455                 if (vma->vm_truncate_count == details->truncate_count)
1456                         continue;
1457
1458                 vba = vma->vm_pgoff;
1459                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1460                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1461                 zba = details->first_index;
1462                 if (zba < vba)
1463                         zba = vba;
1464                 zea = details->last_index;
1465                 if (zea > vea)
1466                         zea = vea;
1467
1468                 if (unmap_mapping_range_vma(vma,
1469                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1470                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1471                                 details) < 0)
1472                         goto restart;
1473         }
1474 }
1475
1476 static inline void unmap_mapping_range_list(struct list_head *head,
1477                                             struct zap_details *details)
1478 {
1479         struct vm_area_struct *vma;
1480
1481         /*
1482          * In nonlinear VMAs there is no correspondence between virtual address
1483          * offset and file offset.  So we must perform an exhaustive search
1484          * across *all* the pages in each nonlinear VMA, not just the pages
1485          * whose virtual address lies outside the file truncation point.
1486          */
1487 restart:
1488         list_for_each_entry(vma, head, shared.vm_set.list) {
1489                 /* Skip quickly over those we have already dealt with */
1490                 if (vma->vm_truncate_count == details->truncate_count)
1491                         continue;
1492                 details->nonlinear_vma = vma;
1493                 if (unmap_mapping_range_vma(vma, vma->vm_start,
1494                                         vma->vm_end, details) < 0)
1495                         goto restart;
1496         }
1497 }
1498
1499 /**
1500  * unmap_mapping_range - unmap the portion of all mmaps
1501  * in the specified address_space corresponding to the specified
1502  * page range in the underlying file.
1503  * @mapping: the address space containing mmaps to be unmapped.
1504  * @holebegin: byte in first page to unmap, relative to the start of
1505  * the underlying file.  This will be rounded down to a PAGE_SIZE
1506  * boundary.  Note that this is different from vmtruncate(), which
1507  * must keep the partial page.  In contrast, we must get rid of
1508  * partial pages.
1509  * @holelen: size of prospective hole in bytes.  This will be rounded
1510  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
1511  * end of the file.
1512  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1513  * but 0 when invalidating pagecache, don't throw away private data.
1514  */
1515 void unmap_mapping_range(struct address_space *mapping,
1516                 loff_t const holebegin, loff_t const holelen, int even_cows)
1517 {
1518         struct zap_details details;
1519         pgoff_t hba = holebegin >> PAGE_SHIFT;
1520         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1521
1522         /* Check for overflow. */
1523         if (sizeof(holelen) > sizeof(hlen)) {
1524                 long long holeend =
1525                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1526                 if (holeend & ~(long long)ULONG_MAX)
1527                         hlen = ULONG_MAX - hba + 1;
1528         }
1529
1530         details.check_mapping = even_cows? NULL: mapping;
1531         details.nonlinear_vma = NULL;
1532         details.first_index = hba;
1533         details.last_index = hba + hlen - 1;
1534         if (details.last_index < details.first_index)
1535                 details.last_index = ULONG_MAX;
1536         details.i_mmap_lock = &mapping->i_mmap_lock;
1537
1538         spin_lock(&mapping->i_mmap_lock);
1539
1540         /* serialize i_size write against truncate_count write */
1541         smp_wmb();
1542         /* Protect against page faults, and endless unmapping loops */
1543         mapping->truncate_count++;
1544         /*
1545          * For archs where spin_lock has inclusive semantics like ia64
1546          * this smp_mb() will prevent to read pagetable contents
1547          * before the truncate_count increment is visible to
1548          * other cpus.
1549          */
1550         smp_mb();
1551         if (unlikely(is_restart_addr(mapping->truncate_count))) {
1552                 if (mapping->truncate_count == 0)
1553                         reset_vma_truncate_counts(mapping);
1554                 mapping->truncate_count++;
1555         }
1556         details.truncate_count = mapping->truncate_count;
1557
1558         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1559                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
1560         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1561                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1562         spin_unlock(&mapping->i_mmap_lock);
1563 }
1564 EXPORT_SYMBOL(unmap_mapping_range);
1565
1566 /*
1567  * Handle all mappings that got truncated by a "truncate()"
1568  * system call.
1569  *
1570  * NOTE! We have to be ready to update the memory sharing
1571  * between the file and the memory map for a potential last
1572  * incomplete page.  Ugly, but necessary.
1573  */
1574 int vmtruncate(struct inode * inode, loff_t offset)
1575 {
1576         struct address_space *mapping = inode->i_mapping;
1577         unsigned long limit;
1578
1579         if (inode->i_size < offset)
1580                 goto do_expand;
1581         /*
1582          * truncation of in-use swapfiles is disallowed - it would cause
1583          * subsequent swapout to scribble on the now-freed blocks.
1584          */
1585         if (IS_SWAPFILE(inode))
1586                 goto out_busy;
1587         i_size_write(inode, offset);
1588         unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1589         truncate_inode_pages(mapping, offset);
1590         goto out_truncate;
1591
1592 do_expand:
1593         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1594         if (limit != RLIM_INFINITY && offset > limit)
1595                 goto out_sig;
1596         if (offset > inode->i_sb->s_maxbytes)
1597                 goto out_big;
1598         i_size_write(inode, offset);
1599
1600 out_truncate:
1601         if (inode->i_op && inode->i_op->truncate)
1602                 inode->i_op->truncate(inode);
1603         return 0;
1604 out_sig:
1605         send_sig(SIGXFSZ, current, 0);
1606 out_big:
1607         return -EFBIG;
1608 out_busy:
1609         return -ETXTBSY;
1610 }
1611
1612 EXPORT_SYMBOL(vmtruncate);
1613
1614 /* 
1615  * Primitive swap readahead code. We simply read an aligned block of
1616  * (1 << page_cluster) entries in the swap area. This method is chosen
1617  * because it doesn't cost us any seek time.  We also make sure to queue
1618  * the 'original' request together with the readahead ones...  
1619  *
1620  * This has been extended to use the NUMA policies from the mm triggering
1621  * the readahead.
1622  *
1623  * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
1624  */
1625 void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
1626 {
1627 #ifdef CONFIG_NUMA
1628         struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
1629 #endif
1630         int i, num;
1631         struct page *new_page;
1632         unsigned long offset;
1633
1634         /*
1635          * Get the number of handles we should do readahead io to.
1636          */
1637         num = valid_swaphandles(entry, &offset);
1638         for (i = 0; i < num; offset++, i++) {
1639                 /* Ok, do the async read-ahead now */
1640                 new_page = read_swap_cache_async(swp_entry(swp_type(entry),
1641                                                            offset), vma, addr);
1642                 if (!new_page)
1643                         break;
1644                 page_cache_release(new_page);
1645 #ifdef CONFIG_NUMA
1646                 /*
1647                  * Find the next applicable VMA for the NUMA policy.
1648                  */
1649                 addr += PAGE_SIZE;
1650                 if (addr == 0)
1651                         vma = NULL;
1652                 if (vma) {
1653                         if (addr >= vma->vm_end) {
1654                                 vma = next_vma;
1655                                 next_vma = vma ? vma->vm_next : NULL;
1656                         }
1657                         if (vma && addr < vma->vm_start)
1658                                 vma = NULL;
1659                 } else {
1660                         if (next_vma && addr >= next_vma->vm_start) {
1661                                 vma = next_vma;
1662                                 next_vma = vma->vm_next;
1663                         }
1664                 }
1665 #endif
1666         }
1667         lru_add_drain();        /* Push any new pages onto the LRU now */
1668 }
1669
1670 /*
1671  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1672  * but allow concurrent faults), and pte mapped but not yet locked.
1673  * We return with mmap_sem still held, but pte unmapped and unlocked.
1674  */
1675 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
1676                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1677                 int write_access, pte_t orig_pte)
1678 {
1679         spinlock_t *ptl;
1680         struct page *page;
1681         swp_entry_t entry;
1682         pte_t pte;
1683         int ret = VM_FAULT_MINOR;
1684
1685         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1686                 goto out;
1687
1688         entry = pte_to_swp_entry(orig_pte);
1689         page = lookup_swap_cache(entry);
1690         if (!page) {
1691                 swapin_readahead(entry, address, vma);
1692                 page = read_swap_cache_async(entry, vma, address);
1693                 if (!page) {
1694                         /*
1695                          * Back out if somebody else faulted in this pte
1696                          * while we released the pte lock.
1697                          */
1698                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1699                         if (likely(pte_same(*page_table, orig_pte)))
1700                                 ret = VM_FAULT_OOM;
1701                         goto unlock;
1702                 }
1703
1704                 /* Had to read the page from swap area: Major fault */
1705                 ret = VM_FAULT_MAJOR;
1706                 inc_page_state(pgmajfault);
1707                 grab_swap_token();
1708         }
1709
1710         mark_page_accessed(page);
1711         lock_page(page);
1712
1713         /*
1714          * Back out if somebody else already faulted in this pte.
1715          */
1716         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1717         if (unlikely(!pte_same(*page_table, orig_pte)))
1718                 goto out_nomap;
1719
1720         if (unlikely(!PageUptodate(page))) {
1721                 ret = VM_FAULT_SIGBUS;
1722                 goto out_nomap;
1723         }
1724
1725         /* The page isn't present yet, go ahead with the fault. */
1726
1727         inc_mm_counter(mm, anon_rss);
1728         pte = mk_pte(page, vma->vm_page_prot);
1729         if (write_access && can_share_swap_page(page)) {
1730                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
1731                 write_access = 0;
1732         }
1733
1734         flush_icache_page(vma, page);
1735         set_pte_at(mm, address, page_table, pte);
1736         page_add_anon_rmap(page, vma, address);
1737
1738         swap_free(entry);
1739         if (vm_swap_full())
1740                 remove_exclusive_swap_page(page);
1741         unlock_page(page);
1742
1743         if (write_access) {
1744                 if (do_wp_page(mm, vma, address,
1745                                 page_table, pmd, ptl, pte) == VM_FAULT_OOM)
1746                         ret = VM_FAULT_OOM;
1747                 goto out;
1748         }
1749
1750         /* No need to invalidate - it was non-present before */
1751         update_mmu_cache(vma, address, pte);
1752         lazy_mmu_prot_update(pte);
1753 unlock:
1754         pte_unmap_unlock(page_table, ptl);
1755 out:
1756         return ret;
1757 out_nomap:
1758         pte_unmap_unlock(page_table, ptl);
1759         unlock_page(page);
1760         page_cache_release(page);
1761         return ret;
1762 }
1763
1764 /*
1765  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1766  * but allow concurrent faults), and pte mapped but not yet locked.
1767  * We return with mmap_sem still held, but pte unmapped and unlocked.
1768  */
1769 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
1770                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1771                 int write_access)
1772 {
1773         struct page *page;
1774         spinlock_t *ptl;
1775         pte_t entry;
1776
1777         if (write_access) {
1778                 /* Allocate our own private page. */
1779                 pte_unmap(page_table);
1780
1781                 if (unlikely(anon_vma_prepare(vma)))
1782                         goto oom;
1783                 page = alloc_zeroed_user_highpage(vma, address);
1784                 if (!page)
1785                         goto oom;
1786
1787                 entry = mk_pte(page, vma->vm_page_prot);
1788                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1789
1790                 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1791                 if (!pte_none(*page_table))
1792                         goto release;
1793                 inc_mm_counter(mm, anon_rss);
1794                 lru_cache_add_active(page);
1795                 SetPageReferenced(page);
1796                 page_add_anon_rmap(page, vma, address);
1797         } else {
1798                 /* Map the ZERO_PAGE - vm_page_prot is readonly */
1799                 page = ZERO_PAGE(address);
1800                 page_cache_get(page);
1801                 entry = mk_pte(page, vma->vm_page_prot);
1802
1803                 ptl = pte_lockptr(mm, pmd);
1804                 spin_lock(ptl);
1805                 if (!pte_none(*page_table))
1806                         goto release;
1807                 inc_mm_counter(mm, file_rss);
1808                 page_add_file_rmap(page);
1809         }
1810
1811         set_pte_at(mm, address, page_table, entry);
1812
1813         /* No need to invalidate - it was non-present before */
1814         update_mmu_cache(vma, address, entry);
1815         lazy_mmu_prot_update(entry);
1816 unlock:
1817         pte_unmap_unlock(page_table, ptl);
1818         return VM_FAULT_MINOR;
1819 release:
1820         page_cache_release(page);
1821         goto unlock;
1822 oom:
1823         return VM_FAULT_OOM;
1824 }
1825
1826 /*
1827  * do_no_page() tries to create a new page mapping. It aggressively
1828  * tries to share with existing pages, but makes a separate copy if
1829  * the "write_access" parameter is true in order to avoid the next
1830  * page fault.
1831  *
1832  * As this is called only for pages that do not currently exist, we
1833  * do not need to flush old virtual caches or the TLB.
1834  *
1835  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1836  * but allow concurrent faults), and pte mapped but not yet locked.
1837  * We return with mmap_sem still held, but pte unmapped and unlocked.
1838  */
1839 static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
1840                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1841                 int write_access)
1842 {
1843         spinlock_t *ptl;
1844         struct page *new_page;
1845         struct address_space *mapping = NULL;
1846         pte_t entry;
1847         unsigned int sequence = 0;
1848         int ret = VM_FAULT_MINOR;
1849         int anon = 0;
1850
1851         pte_unmap(page_table);
1852
1853         if (vma->vm_file) {
1854                 mapping = vma->vm_file->f_mapping;
1855                 sequence = mapping->truncate_count;
1856                 smp_rmb(); /* serializes i_size against truncate_count */
1857         }
1858 retry:
1859         new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
1860         /*
1861          * No smp_rmb is needed here as long as there's a full
1862          * spin_lock/unlock sequence inside the ->nopage callback
1863          * (for the pagecache lookup) that acts as an implicit
1864          * smp_mb() and prevents the i_size read to happen
1865          * after the next truncate_count read.
1866          */
1867
1868         /* no page was available -- either SIGBUS or OOM */
1869         if (new_page == NOPAGE_SIGBUS)
1870                 return VM_FAULT_SIGBUS;
1871         if (new_page == NOPAGE_OOM)
1872                 return VM_FAULT_OOM;
1873
1874         /*
1875          * Should we do an early C-O-W break?
1876          */
1877         if (write_access && !(vma->vm_flags & VM_SHARED)) {
1878                 struct page *page;
1879
1880                 if (unlikely(anon_vma_prepare(vma)))
1881                         goto oom;
1882                 page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1883                 if (!page)
1884                         goto oom;
1885                 copy_user_highpage(page, new_page, address);
1886                 page_cache_release(new_page);
1887                 new_page = page;
1888                 anon = 1;
1889         }
1890
1891         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
1892         /*
1893          * For a file-backed vma, someone could have truncated or otherwise
1894          * invalidated this page.  If unmap_mapping_range got called,
1895          * retry getting the page.
1896          */
1897         if (mapping && unlikely(sequence != mapping->truncate_count)) {
1898                 pte_unmap_unlock(page_table, ptl);
1899                 page_cache_release(new_page);
1900                 cond_resched();
1901                 sequence = mapping->truncate_count;
1902                 smp_rmb();
1903                 goto retry;
1904         }
1905
1906         /*
1907          * This silly early PAGE_DIRTY setting removes a race
1908          * due to the bad i386 page protection. But it's valid
1909          * for other architectures too.
1910          *
1911          * Note that if write_access is true, we either now have
1912          * an exclusive copy of the page, or this is a shared mapping,
1913          * so we can make it writable and dirty to avoid having to
1914          * handle that later.
1915          */
1916         /* Only go through if we didn't race with anybody else... */
1917         if (pte_none(*page_table)) {
1918                 flush_icache_page(vma, new_page);
1919                 entry = mk_pte(new_page, vma->vm_page_prot);
1920                 if (write_access)
1921                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1922                 set_pte_at(mm, address, page_table, entry);
1923                 if (anon) {
1924                         inc_mm_counter(mm, anon_rss);
1925                         lru_cache_add_active(new_page);
1926                         page_add_anon_rmap(new_page, vma, address);
1927                 } else if (!(vma->vm_flags & VM_RESERVED)) {
1928                         inc_mm_counter(mm, file_rss);
1929                         page_add_file_rmap(new_page);
1930                 }
1931         } else {
1932                 /* One of our sibling threads was faster, back out. */
1933                 page_cache_release(new_page);
1934                 goto unlock;
1935         }
1936
1937         /* no need to invalidate: a not-present page shouldn't be cached */
1938         update_mmu_cache(vma, address, entry);
1939         lazy_mmu_prot_update(entry);
1940 unlock:
1941         pte_unmap_unlock(page_table, ptl);
1942         return ret;
1943 oom:
1944         page_cache_release(new_page);
1945         return VM_FAULT_OOM;
1946 }
1947
1948 /*
1949  * Fault of a previously existing named mapping. Repopulate the pte
1950  * from the encoded file_pte if possible. This enables swappable
1951  * nonlinear vmas.
1952  *
1953  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1954  * but allow concurrent faults), and pte mapped but not yet locked.
1955  * We return with mmap_sem still held, but pte unmapped and unlocked.
1956  */
1957 static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma,
1958                 unsigned long address, pte_t *page_table, pmd_t *pmd,
1959                 int write_access, pte_t orig_pte)
1960 {
1961         pgoff_t pgoff;
1962         int err;
1963
1964         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
1965                 return VM_FAULT_MINOR;
1966
1967         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
1968                 /*
1969                  * Page table corrupted: show pte and kill process.
1970                  */
1971                 print_bad_pte(vma, orig_pte, address);
1972                 return VM_FAULT_OOM;
1973         }
1974         /* We can then assume vm->vm_ops && vma->vm_ops->populate */
1975
1976         pgoff = pte_to_pgoff(orig_pte);
1977         err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE,
1978                                         vma->vm_page_prot, pgoff, 0);
1979         if (err == -ENOMEM)
1980                 return VM_FAULT_OOM;
1981         if (err)
1982                 return VM_FAULT_SIGBUS;
1983         return VM_FAULT_MAJOR;
1984 }
1985
1986 /*
1987  * These routines also need to handle stuff like marking pages dirty
1988  * and/or accessed for architectures that don't do it in hardware (most
1989  * RISC architectures).  The early dirtying is also good on the i386.
1990  *
1991  * There is also a hook called "update_mmu_cache()" that architectures
1992  * with external mmu caches can use to update those (ie the Sparc or
1993  * PowerPC hashed page tables that act as extended TLBs).
1994  *
1995  * We enter with non-exclusive mmap_sem (to exclude vma changes,
1996  * but allow concurrent faults), and pte mapped but not yet locked.
1997  * We return with mmap_sem still held, but pte unmapped and unlocked.
1998  */
1999 static inline int handle_pte_fault(struct mm_struct *mm,
2000                 struct vm_area_struct *vma, unsigned long address,
2001                 pte_t *pte, pmd_t *pmd, int write_access)
2002 {
2003         pte_t entry;
2004         pte_t old_entry;
2005         spinlock_t *ptl;
2006
2007         old_entry = entry = *pte;
2008         if (!pte_present(entry)) {
2009                 if (pte_none(entry)) {
2010                         if (!vma->vm_ops || !vma->vm_ops->nopage)
2011                                 return do_anonymous_page(mm, vma, address,
2012                                         pte, pmd, write_access);
2013                         return do_no_page(mm, vma, address,
2014                                         pte, pmd, write_access);
2015                 }
2016                 if (pte_file(entry))
2017                         return do_file_page(mm, vma, address,
2018                                         pte, pmd, write_access, entry);
2019                 return do_swap_page(mm, vma, address,
2020                                         pte, pmd, write_access, entry);
2021         }
2022
2023         ptl = pte_lockptr(mm, pmd);
2024         spin_lock(ptl);
2025         if (unlikely(!pte_same(*pte, entry)))
2026                 goto unlock;
2027         if (write_access) {
2028                 if (!pte_write(entry))
2029                         return do_wp_page(mm, vma, address,
2030                                         pte, pmd, ptl, entry);
2031                 entry = pte_mkdirty(entry);
2032         }
2033         entry = pte_mkyoung(entry);
2034         if (!pte_same(old_entry, entry)) {
2035                 ptep_set_access_flags(vma, address, pte, entry, write_access);
2036                 update_mmu_cache(vma, address, entry);
2037                 lazy_mmu_prot_update(entry);
2038         } else {
2039                 /*
2040                  * This is needed only for protection faults but the arch code
2041                  * is not yet telling us if this is a protection fault or not.
2042                  * This still avoids useless tlb flushes for .text page faults
2043                  * with threads.
2044                  */
2045                 if (write_access)
2046                         flush_tlb_page(vma, address);
2047         }
2048 unlock:
2049         pte_unmap_unlock(pte, ptl);
2050         return VM_FAULT_MINOR;
2051 }
2052
2053 /*
2054  * By the time we get here, we already hold the mm semaphore
2055  */
2056 int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
2057                 unsigned long address, int write_access)
2058 {
2059         pgd_t *pgd;
2060         pud_t *pud;
2061         pmd_t *pmd;
2062         pte_t *pte;
2063
2064         __set_current_state(TASK_RUNNING);
2065
2066         inc_page_state(pgfault);
2067
2068         if (unlikely(is_vm_hugetlb_page(vma)))
2069                 return hugetlb_fault(mm, vma, address, write_access);
2070
2071         pgd = pgd_offset(mm, address);
2072         pud = pud_alloc(mm, pgd, address);
2073         if (!pud)
2074                 return VM_FAULT_OOM;
2075         pmd = pmd_alloc(mm, pud, address);
2076         if (!pmd)
2077                 return VM_FAULT_OOM;
2078         pte = pte_alloc_map(mm, pmd, address);
2079         if (!pte)
2080                 return VM_FAULT_OOM;
2081
2082         return handle_pte_fault(mm, vma, address, pte, pmd, write_access);
2083 }
2084
2085 #ifndef __PAGETABLE_PUD_FOLDED
2086 /*
2087  * Allocate page upper directory.
2088  * We've already handled the fast-path in-line.
2089  */
2090 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2091 {
2092         pud_t *new = pud_alloc_one(mm, address);
2093         if (!new)
2094                 return -ENOMEM;
2095
2096         spin_lock(&mm->page_table_lock);
2097         if (pgd_present(*pgd))          /* Another has populated it */
2098                 pud_free(new);
2099         else
2100                 pgd_populate(mm, pgd, new);
2101         spin_unlock(&mm->page_table_lock);
2102         return 0;
2103 }
2104 #endif /* __PAGETABLE_PUD_FOLDED */
2105
2106 #ifndef __PAGETABLE_PMD_FOLDED
2107 /*
2108  * Allocate page middle directory.
2109  * We've already handled the fast-path in-line.
2110  */
2111 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2112 {
2113         pmd_t *new = pmd_alloc_one(mm, address);
2114         if (!new)
2115                 return -ENOMEM;
2116
2117         spin_lock(&mm->page_table_lock);
2118 #ifndef __ARCH_HAS_4LEVEL_HACK
2119         if (pud_present(*pud))          /* Another has populated it */
2120                 pmd_free(new);
2121         else
2122                 pud_populate(mm, pud, new);
2123 #else
2124         if (pgd_present(*pud))          /* Another has populated it */
2125                 pmd_free(new);
2126         else
2127                 pgd_populate(mm, pud, new);
2128 #endif /* __ARCH_HAS_4LEVEL_HACK */
2129         spin_unlock(&mm->page_table_lock);
2130         return 0;
2131 }
2132 #endif /* __PAGETABLE_PMD_FOLDED */
2133
2134 int make_pages_present(unsigned long addr, unsigned long end)
2135 {
2136         int ret, len, write;
2137         struct vm_area_struct * vma;
2138
2139         vma = find_vma(current->mm, addr);
2140         if (!vma)
2141                 return -1;
2142         write = (vma->vm_flags & VM_WRITE) != 0;
2143         if (addr >= end)
2144                 BUG();
2145         if (end > vma->vm_end)
2146                 BUG();
2147         len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
2148         ret = get_user_pages(current, current->mm, addr,
2149                         len, write, 0, NULL, NULL);
2150         if (ret < 0)
2151                 return ret;
2152         return ret == len ? 0 : -1;
2153 }
2154
2155 /* 
2156  * Map a vmalloc()-space virtual address to the physical page.
2157  */
2158 struct page * vmalloc_to_page(void * vmalloc_addr)
2159 {
2160         unsigned long addr = (unsigned long) vmalloc_addr;
2161         struct page *page = NULL;
2162         pgd_t *pgd = pgd_offset_k(addr);
2163         pud_t *pud;
2164         pmd_t *pmd;
2165         pte_t *ptep, pte;
2166   
2167         if (!pgd_none(*pgd)) {
2168                 pud = pud_offset(pgd, addr);
2169                 if (!pud_none(*pud)) {
2170                         pmd = pmd_offset(pud, addr);
2171                         if (!pmd_none(*pmd)) {
2172                                 ptep = pte_offset_map(pmd, addr);
2173                                 pte = *ptep;
2174                                 if (pte_present(pte))
2175                                         page = pte_page(pte);
2176                                 pte_unmap(ptep);
2177                         }
2178                 }
2179         }
2180         return page;
2181 }
2182
2183 EXPORT_SYMBOL(vmalloc_to_page);
2184
2185 /*
2186  * Map a vmalloc()-space virtual address to the physical page frame number.
2187  */
2188 unsigned long vmalloc_to_pfn(void * vmalloc_addr)
2189 {
2190         return page_to_pfn(vmalloc_to_page(vmalloc_addr));
2191 }
2192
2193 EXPORT_SYMBOL(vmalloc_to_pfn);
2194
2195 #if !defined(__HAVE_ARCH_GATE_AREA)
2196
2197 #if defined(AT_SYSINFO_EHDR)
2198 static struct vm_area_struct gate_vma;
2199
2200 static int __init gate_vma_init(void)
2201 {
2202         gate_vma.vm_mm = NULL;
2203         gate_vma.vm_start = FIXADDR_USER_START;
2204         gate_vma.vm_end = FIXADDR_USER_END;
2205         gate_vma.vm_page_prot = PAGE_READONLY;
2206         gate_vma.vm_flags = VM_RESERVED;
2207         return 0;
2208 }
2209 __initcall(gate_vma_init);
2210 #endif
2211
2212 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2213 {
2214 #ifdef AT_SYSINFO_EHDR
2215         return &gate_vma;
2216 #else
2217         return NULL;
2218 #endif
2219 }
2220
2221 int in_gate_area_no_task(unsigned long addr)
2222 {
2223 #ifdef AT_SYSINFO_EHDR
2224         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2225                 return 1;
2226 #endif
2227         return 0;
2228 }
2229
2230 #endif  /* __HAVE_ARCH_GATE_AREA */