[PATCH] freepgt: free_pgtables use vma list
[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_DISCONTIGMEM
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_free_tlb(tlb, page);
118         dec_page_state(nr_page_table_pages);
119         tlb->mm->nr_ptes--;
120 }
121
122 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
123                                 unsigned long addr, unsigned long end,
124                                 unsigned long floor, unsigned long ceiling)
125 {
126         pmd_t *pmd;
127         unsigned long next;
128         unsigned long start;
129
130         start = addr;
131         pmd = pmd_offset(pud, addr);
132         do {
133                 next = pmd_addr_end(addr, end);
134                 if (pmd_none_or_clear_bad(pmd))
135                         continue;
136                 free_pte_range(tlb, pmd);
137         } while (pmd++, addr = next, addr != end);
138
139         start &= PUD_MASK;
140         if (start < floor)
141                 return;
142         if (ceiling) {
143                 ceiling &= PUD_MASK;
144                 if (!ceiling)
145                         return;
146         }
147         if (end - 1 > ceiling - 1)
148                 return;
149
150         pmd = pmd_offset(pud, start);
151         pud_clear(pud);
152         pmd_free_tlb(tlb, pmd);
153 }
154
155 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
156                                 unsigned long addr, unsigned long end,
157                                 unsigned long floor, unsigned long ceiling)
158 {
159         pud_t *pud;
160         unsigned long next;
161         unsigned long start;
162
163         start = addr;
164         pud = pud_offset(pgd, addr);
165         do {
166                 next = pud_addr_end(addr, end);
167                 if (pud_none_or_clear_bad(pud))
168                         continue;
169                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
170         } while (pud++, addr = next, addr != end);
171
172         start &= PGDIR_MASK;
173         if (start < floor)
174                 return;
175         if (ceiling) {
176                 ceiling &= PGDIR_MASK;
177                 if (!ceiling)
178                         return;
179         }
180         if (end - 1 > ceiling - 1)
181                 return;
182
183         pud = pud_offset(pgd, start);
184         pgd_clear(pgd);
185         pud_free_tlb(tlb, pud);
186 }
187
188 /*
189  * This function frees user-level page tables of a process.
190  *
191  * Must be called with pagetable lock held.
192  */
193 static inline void free_pgd_range(struct mmu_gather *tlb,
194                         unsigned long addr, unsigned long end,
195                         unsigned long floor, unsigned long ceiling)
196 {
197         pgd_t *pgd;
198         unsigned long next;
199         unsigned long start;
200
201         /*
202          * The next few lines have given us lots of grief...
203          *
204          * Why are we testing PMD* at this top level?  Because often
205          * there will be no work to do at all, and we'd prefer not to
206          * go all the way down to the bottom just to discover that.
207          *
208          * Why all these "- 1"s?  Because 0 represents both the bottom
209          * of the address space and the top of it (using -1 for the
210          * top wouldn't help much: the masks would do the wrong thing).
211          * The rule is that addr 0 and floor 0 refer to the bottom of
212          * the address space, but end 0 and ceiling 0 refer to the top
213          * Comparisons need to use "end - 1" and "ceiling - 1" (though
214          * that end 0 case should be mythical).
215          *
216          * Wherever addr is brought up or ceiling brought down, we must
217          * be careful to reject "the opposite 0" before it confuses the
218          * subsequent tests.  But what about where end is brought down
219          * by PMD_SIZE below? no, end can't go down to 0 there.
220          *
221          * Whereas we round start (addr) and ceiling down, by different
222          * masks at different levels, in order to test whether a table
223          * now has no other vmas using it, so can be freed, we don't
224          * bother to round floor or end up - the tests don't need that.
225          */
226
227         addr &= PMD_MASK;
228         if (addr < floor) {
229                 addr += PMD_SIZE;
230                 if (!addr)
231                         return;
232         }
233         if (ceiling) {
234                 ceiling &= PMD_MASK;
235                 if (!ceiling)
236                         return;
237         }
238         if (end - 1 > ceiling - 1)
239                 end -= PMD_SIZE;
240         if (addr > end - 1)
241                 return;
242
243         start = addr;
244         pgd = pgd_offset(tlb->mm, addr);
245         do {
246                 next = pgd_addr_end(addr, end);
247                 if (pgd_none_or_clear_bad(pgd))
248                         continue;
249                 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
250         } while (pgd++, addr = next, addr != end);
251
252         if (!tlb_is_full_mm(tlb))
253                 flush_tlb_pgtables(tlb->mm, start, end);
254 }
255
256 void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
257                                 unsigned long floor, unsigned long ceiling)
258 {
259         while (vma) {
260                 struct vm_area_struct *next = vma->vm_next;
261                 unsigned long addr = vma->vm_start;
262
263                 /* Optimization: gather nearby vmas into a single call down */
264                 while (next && next->vm_start <= vma->vm_end + PMD_SIZE) {
265                         vma = next;
266                         next = vma->vm_next;
267                 }
268                 free_pgd_range(*tlb, addr, vma->vm_end,
269                                 floor, next? next->vm_start: ceiling);
270                 vma = next;
271         }
272 }
273
274 pte_t fastcall * pte_alloc_map(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
275 {
276         if (!pmd_present(*pmd)) {
277                 struct page *new;
278
279                 spin_unlock(&mm->page_table_lock);
280                 new = pte_alloc_one(mm, address);
281                 spin_lock(&mm->page_table_lock);
282                 if (!new)
283                         return NULL;
284                 /*
285                  * Because we dropped the lock, we should re-check the
286                  * entry, as somebody else could have populated it..
287                  */
288                 if (pmd_present(*pmd)) {
289                         pte_free(new);
290                         goto out;
291                 }
292                 mm->nr_ptes++;
293                 inc_page_state(nr_page_table_pages);
294                 pmd_populate(mm, pmd, new);
295         }
296 out:
297         return pte_offset_map(pmd, address);
298 }
299
300 pte_t fastcall * pte_alloc_kernel(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
301 {
302         if (!pmd_present(*pmd)) {
303                 pte_t *new;
304
305                 spin_unlock(&mm->page_table_lock);
306                 new = pte_alloc_one_kernel(mm, address);
307                 spin_lock(&mm->page_table_lock);
308                 if (!new)
309                         return NULL;
310
311                 /*
312                  * Because we dropped the lock, we should re-check the
313                  * entry, as somebody else could have populated it..
314                  */
315                 if (pmd_present(*pmd)) {
316                         pte_free_kernel(new);
317                         goto out;
318                 }
319                 pmd_populate_kernel(mm, pmd, new);
320         }
321 out:
322         return pte_offset_kernel(pmd, address);
323 }
324
325 /*
326  * copy one vm_area from one task to the other. Assumes the page tables
327  * already present in the new task to be cleared in the whole range
328  * covered by this vma.
329  *
330  * dst->page_table_lock is held on entry and exit,
331  * but may be dropped within p[mg]d_alloc() and pte_alloc_map().
332  */
333
334 static inline void
335 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
336                 pte_t *dst_pte, pte_t *src_pte, unsigned long vm_flags,
337                 unsigned long addr)
338 {
339         pte_t pte = *src_pte;
340         struct page *page;
341         unsigned long pfn;
342
343         /* pte contains position in swap or file, so copy. */
344         if (unlikely(!pte_present(pte))) {
345                 if (!pte_file(pte)) {
346                         swap_duplicate(pte_to_swp_entry(pte));
347                         /* make sure dst_mm is on swapoff's mmlist. */
348                         if (unlikely(list_empty(&dst_mm->mmlist))) {
349                                 spin_lock(&mmlist_lock);
350                                 list_add(&dst_mm->mmlist, &src_mm->mmlist);
351                                 spin_unlock(&mmlist_lock);
352                         }
353                 }
354                 set_pte_at(dst_mm, addr, dst_pte, pte);
355                 return;
356         }
357
358         pfn = pte_pfn(pte);
359         /* the pte points outside of valid memory, the
360          * mapping is assumed to be good, meaningful
361          * and not mapped via rmap - duplicate the
362          * mapping as is.
363          */
364         page = NULL;
365         if (pfn_valid(pfn))
366                 page = pfn_to_page(pfn);
367
368         if (!page || PageReserved(page)) {
369                 set_pte_at(dst_mm, addr, dst_pte, pte);
370                 return;
371         }
372
373         /*
374          * If it's a COW mapping, write protect it both
375          * in the parent and the child
376          */
377         if ((vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE) {
378                 ptep_set_wrprotect(src_mm, addr, src_pte);
379                 pte = *src_pte;
380         }
381
382         /*
383          * If it's a shared mapping, mark it clean in
384          * the child
385          */
386         if (vm_flags & VM_SHARED)
387                 pte = pte_mkclean(pte);
388         pte = pte_mkold(pte);
389         get_page(page);
390         inc_mm_counter(dst_mm, rss);
391         if (PageAnon(page))
392                 inc_mm_counter(dst_mm, anon_rss);
393         set_pte_at(dst_mm, addr, dst_pte, pte);
394         page_dup_rmap(page);
395 }
396
397 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
398                 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
399                 unsigned long addr, unsigned long end)
400 {
401         pte_t *src_pte, *dst_pte;
402         unsigned long vm_flags = vma->vm_flags;
403         int progress;
404
405 again:
406         dst_pte = pte_alloc_map(dst_mm, dst_pmd, addr);
407         if (!dst_pte)
408                 return -ENOMEM;
409         src_pte = pte_offset_map_nested(src_pmd, addr);
410
411         progress = 0;
412         spin_lock(&src_mm->page_table_lock);
413         do {
414                 /*
415                  * We are holding two locks at this point - either of them
416                  * could generate latencies in another task on another CPU.
417                  */
418                 if (progress >= 32 && (need_resched() ||
419                     need_lockbreak(&src_mm->page_table_lock) ||
420                     need_lockbreak(&dst_mm->page_table_lock)))
421                         break;
422                 if (pte_none(*src_pte)) {
423                         progress++;
424                         continue;
425                 }
426                 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vm_flags, addr);
427                 progress += 8;
428         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
429         spin_unlock(&src_mm->page_table_lock);
430
431         pte_unmap_nested(src_pte - 1);
432         pte_unmap(dst_pte - 1);
433         cond_resched_lock(&dst_mm->page_table_lock);
434         if (addr != end)
435                 goto again;
436         return 0;
437 }
438
439 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
440                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
441                 unsigned long addr, unsigned long end)
442 {
443         pmd_t *src_pmd, *dst_pmd;
444         unsigned long next;
445
446         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
447         if (!dst_pmd)
448                 return -ENOMEM;
449         src_pmd = pmd_offset(src_pud, addr);
450         do {
451                 next = pmd_addr_end(addr, end);
452                 if (pmd_none_or_clear_bad(src_pmd))
453                         continue;
454                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
455                                                 vma, addr, next))
456                         return -ENOMEM;
457         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
458         return 0;
459 }
460
461 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
462                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
463                 unsigned long addr, unsigned long end)
464 {
465         pud_t *src_pud, *dst_pud;
466         unsigned long next;
467
468         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
469         if (!dst_pud)
470                 return -ENOMEM;
471         src_pud = pud_offset(src_pgd, addr);
472         do {
473                 next = pud_addr_end(addr, end);
474                 if (pud_none_or_clear_bad(src_pud))
475                         continue;
476                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
477                                                 vma, addr, next))
478                         return -ENOMEM;
479         } while (dst_pud++, src_pud++, addr = next, addr != end);
480         return 0;
481 }
482
483 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
484                 struct vm_area_struct *vma)
485 {
486         pgd_t *src_pgd, *dst_pgd;
487         unsigned long next;
488         unsigned long addr = vma->vm_start;
489         unsigned long end = vma->vm_end;
490
491         if (is_vm_hugetlb_page(vma))
492                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
493
494         dst_pgd = pgd_offset(dst_mm, addr);
495         src_pgd = pgd_offset(src_mm, addr);
496         do {
497                 next = pgd_addr_end(addr, end);
498                 if (pgd_none_or_clear_bad(src_pgd))
499                         continue;
500                 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
501                                                 vma, addr, next))
502                         return -ENOMEM;
503         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
504         return 0;
505 }
506
507 static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
508                                 unsigned long addr, unsigned long end,
509                                 struct zap_details *details)
510 {
511         pte_t *pte;
512
513         pte = pte_offset_map(pmd, addr);
514         do {
515                 pte_t ptent = *pte;
516                 if (pte_none(ptent))
517                         continue;
518                 if (pte_present(ptent)) {
519                         struct page *page = NULL;
520                         unsigned long pfn = pte_pfn(ptent);
521                         if (pfn_valid(pfn)) {
522                                 page = pfn_to_page(pfn);
523                                 if (PageReserved(page))
524                                         page = NULL;
525                         }
526                         if (unlikely(details) && page) {
527                                 /*
528                                  * unmap_shared_mapping_pages() wants to
529                                  * invalidate cache without truncating:
530                                  * unmap shared but keep private pages.
531                                  */
532                                 if (details->check_mapping &&
533                                     details->check_mapping != page->mapping)
534                                         continue;
535                                 /*
536                                  * Each page->index must be checked when
537                                  * invalidating or truncating nonlinear.
538                                  */
539                                 if (details->nonlinear_vma &&
540                                     (page->index < details->first_index ||
541                                      page->index > details->last_index))
542                                         continue;
543                         }
544                         ptent = ptep_get_and_clear(tlb->mm, addr, pte);
545                         tlb_remove_tlb_entry(tlb, pte, addr);
546                         if (unlikely(!page))
547                                 continue;
548                         if (unlikely(details) && details->nonlinear_vma
549                             && linear_page_index(details->nonlinear_vma,
550                                                 addr) != page->index)
551                                 set_pte_at(tlb->mm, addr, pte,
552                                            pgoff_to_pte(page->index));
553                         if (pte_dirty(ptent))
554                                 set_page_dirty(page);
555                         if (PageAnon(page))
556                                 dec_mm_counter(tlb->mm, anon_rss);
557                         else if (pte_young(ptent))
558                                 mark_page_accessed(page);
559                         tlb->freed++;
560                         page_remove_rmap(page);
561                         tlb_remove_page(tlb, page);
562                         continue;
563                 }
564                 /*
565                  * If details->check_mapping, we leave swap entries;
566                  * if details->nonlinear_vma, we leave file entries.
567                  */
568                 if (unlikely(details))
569                         continue;
570                 if (!pte_file(ptent))
571                         free_swap_and_cache(pte_to_swp_entry(ptent));
572                 pte_clear(tlb->mm, addr, pte);
573         } while (pte++, addr += PAGE_SIZE, addr != end);
574         pte_unmap(pte - 1);
575 }
576
577 static inline void zap_pmd_range(struct mmu_gather *tlb, pud_t *pud,
578                                 unsigned long addr, unsigned long end,
579                                 struct zap_details *details)
580 {
581         pmd_t *pmd;
582         unsigned long next;
583
584         pmd = pmd_offset(pud, addr);
585         do {
586                 next = pmd_addr_end(addr, end);
587                 if (pmd_none_or_clear_bad(pmd))
588                         continue;
589                 zap_pte_range(tlb, pmd, addr, next, details);
590         } while (pmd++, addr = next, addr != end);
591 }
592
593 static inline void zap_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
594                                 unsigned long addr, unsigned long end,
595                                 struct zap_details *details)
596 {
597         pud_t *pud;
598         unsigned long next;
599
600         pud = pud_offset(pgd, addr);
601         do {
602                 next = pud_addr_end(addr, end);
603                 if (pud_none_or_clear_bad(pud))
604                         continue;
605                 zap_pmd_range(tlb, pud, addr, next, details);
606         } while (pud++, addr = next, addr != end);
607 }
608
609 static void unmap_page_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
610                                 unsigned long addr, unsigned long end,
611                                 struct zap_details *details)
612 {
613         pgd_t *pgd;
614         unsigned long next;
615
616         if (details && !details->check_mapping && !details->nonlinear_vma)
617                 details = NULL;
618
619         BUG_ON(addr >= end);
620         tlb_start_vma(tlb, vma);
621         pgd = pgd_offset(vma->vm_mm, addr);
622         do {
623                 next = pgd_addr_end(addr, end);
624                 if (pgd_none_or_clear_bad(pgd))
625                         continue;
626                 zap_pud_range(tlb, pgd, addr, next, details);
627         } while (pgd++, addr = next, addr != end);
628         tlb_end_vma(tlb, vma);
629 }
630
631 #ifdef CONFIG_PREEMPT
632 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
633 #else
634 /* No preempt: go for improved straight-line efficiency */
635 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
636 #endif
637
638 /**
639  * unmap_vmas - unmap a range of memory covered by a list of vma's
640  * @tlbp: address of the caller's struct mmu_gather
641  * @mm: the controlling mm_struct
642  * @vma: the starting vma
643  * @start_addr: virtual address at which to start unmapping
644  * @end_addr: virtual address at which to end unmapping
645  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
646  * @details: details of nonlinear truncation or shared cache invalidation
647  *
648  * Returns the number of vma's which were covered by the unmapping.
649  *
650  * Unmap all pages in the vma list.  Called under page_table_lock.
651  *
652  * We aim to not hold page_table_lock for too long (for scheduling latency
653  * reasons).  So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
654  * return the ending mmu_gather to the caller.
655  *
656  * Only addresses between `start' and `end' will be unmapped.
657  *
658  * The VMA list must be sorted in ascending virtual address order.
659  *
660  * unmap_vmas() assumes that the caller will flush the whole unmapped address
661  * range after unmap_vmas() returns.  So the only responsibility here is to
662  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
663  * drops the lock and schedules.
664  */
665 int unmap_vmas(struct mmu_gather **tlbp, struct mm_struct *mm,
666                 struct vm_area_struct *vma, unsigned long start_addr,
667                 unsigned long end_addr, unsigned long *nr_accounted,
668                 struct zap_details *details)
669 {
670         unsigned long zap_bytes = ZAP_BLOCK_SIZE;
671         unsigned long tlb_start = 0;    /* For tlb_finish_mmu */
672         int tlb_start_valid = 0;
673         int ret = 0;
674         spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
675         int fullmm = tlb_is_full_mm(*tlbp);
676
677         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
678                 unsigned long start;
679                 unsigned long end;
680
681                 start = max(vma->vm_start, start_addr);
682                 if (start >= vma->vm_end)
683                         continue;
684                 end = min(vma->vm_end, end_addr);
685                 if (end <= vma->vm_start)
686                         continue;
687
688                 if (vma->vm_flags & VM_ACCOUNT)
689                         *nr_accounted += (end - start) >> PAGE_SHIFT;
690
691                 ret++;
692                 while (start != end) {
693                         unsigned long block;
694
695                         if (!tlb_start_valid) {
696                                 tlb_start = start;
697                                 tlb_start_valid = 1;
698                         }
699
700                         if (is_vm_hugetlb_page(vma)) {
701                                 block = end - start;
702                                 unmap_hugepage_range(vma, start, end);
703                         } else {
704                                 block = min(zap_bytes, end - start);
705                                 unmap_page_range(*tlbp, vma, start,
706                                                 start + block, details);
707                         }
708
709                         start += block;
710                         zap_bytes -= block;
711                         if ((long)zap_bytes > 0)
712                                 continue;
713
714                         tlb_finish_mmu(*tlbp, tlb_start, start);
715
716                         if (need_resched() ||
717                                 need_lockbreak(&mm->page_table_lock) ||
718                                 (i_mmap_lock && need_lockbreak(i_mmap_lock))) {
719                                 if (i_mmap_lock) {
720                                         /* must reset count of rss freed */
721                                         *tlbp = tlb_gather_mmu(mm, fullmm);
722                                         details->break_addr = start;
723                                         goto out;
724                                 }
725                                 spin_unlock(&mm->page_table_lock);
726                                 cond_resched();
727                                 spin_lock(&mm->page_table_lock);
728                         }
729
730                         *tlbp = tlb_gather_mmu(mm, fullmm);
731                         tlb_start_valid = 0;
732                         zap_bytes = ZAP_BLOCK_SIZE;
733                 }
734         }
735 out:
736         return ret;
737 }
738
739 /**
740  * zap_page_range - remove user pages in a given range
741  * @vma: vm_area_struct holding the applicable pages
742  * @address: starting address of pages to zap
743  * @size: number of bytes to zap
744  * @details: details of nonlinear truncation or shared cache invalidation
745  */
746 void zap_page_range(struct vm_area_struct *vma, unsigned long address,
747                 unsigned long size, struct zap_details *details)
748 {
749         struct mm_struct *mm = vma->vm_mm;
750         struct mmu_gather *tlb;
751         unsigned long end = address + size;
752         unsigned long nr_accounted = 0;
753
754         if (is_vm_hugetlb_page(vma)) {
755                 zap_hugepage_range(vma, address, size);
756                 return;
757         }
758
759         lru_add_drain();
760         spin_lock(&mm->page_table_lock);
761         tlb = tlb_gather_mmu(mm, 0);
762         unmap_vmas(&tlb, mm, vma, address, end, &nr_accounted, details);
763         tlb_finish_mmu(tlb, address, end);
764         spin_unlock(&mm->page_table_lock);
765 }
766
767 /*
768  * Do a quick page-table lookup for a single page.
769  * mm->page_table_lock must be held.
770  */
771 static struct page *
772 __follow_page(struct mm_struct *mm, unsigned long address, int read, int write)
773 {
774         pgd_t *pgd;
775         pud_t *pud;
776         pmd_t *pmd;
777         pte_t *ptep, pte;
778         unsigned long pfn;
779         struct page *page;
780
781         page = follow_huge_addr(mm, address, write);
782         if (! IS_ERR(page))
783                 return page;
784
785         pgd = pgd_offset(mm, address);
786         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
787                 goto out;
788
789         pud = pud_offset(pgd, address);
790         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
791                 goto out;
792         
793         pmd = pmd_offset(pud, address);
794         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
795                 goto out;
796         if (pmd_huge(*pmd))
797                 return follow_huge_pmd(mm, address, pmd, write);
798
799         ptep = pte_offset_map(pmd, address);
800         if (!ptep)
801                 goto out;
802
803         pte = *ptep;
804         pte_unmap(ptep);
805         if (pte_present(pte)) {
806                 if (write && !pte_write(pte))
807                         goto out;
808                 if (read && !pte_read(pte))
809                         goto out;
810                 pfn = pte_pfn(pte);
811                 if (pfn_valid(pfn)) {
812                         page = pfn_to_page(pfn);
813                         if (write && !pte_dirty(pte) && !PageDirty(page))
814                                 set_page_dirty(page);
815                         mark_page_accessed(page);
816                         return page;
817                 }
818         }
819
820 out:
821         return NULL;
822 }
823
824 struct page *
825 follow_page(struct mm_struct *mm, unsigned long address, int write)
826 {
827         return __follow_page(mm, address, /*read*/0, write);
828 }
829
830 int
831 check_user_page_readable(struct mm_struct *mm, unsigned long address)
832 {
833         return __follow_page(mm, address, /*read*/1, /*write*/0) != NULL;
834 }
835
836 EXPORT_SYMBOL(check_user_page_readable);
837
838 /* 
839  * Given a physical address, is there a useful struct page pointing to
840  * it?  This may become more complex in the future if we start dealing
841  * with IO-aperture pages for direct-IO.
842  */
843
844 static inline struct page *get_page_map(struct page *page)
845 {
846         if (!pfn_valid(page_to_pfn(page)))
847                 return NULL;
848         return page;
849 }
850
851
852 static inline int
853 untouched_anonymous_page(struct mm_struct* mm, struct vm_area_struct *vma,
854                          unsigned long address)
855 {
856         pgd_t *pgd;
857         pud_t *pud;
858         pmd_t *pmd;
859
860         /* Check if the vma is for an anonymous mapping. */
861         if (vma->vm_ops && vma->vm_ops->nopage)
862                 return 0;
863
864         /* Check if page directory entry exists. */
865         pgd = pgd_offset(mm, address);
866         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
867                 return 1;
868
869         pud = pud_offset(pgd, address);
870         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
871                 return 1;
872
873         /* Check if page middle directory entry exists. */
874         pmd = pmd_offset(pud, address);
875         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
876                 return 1;
877
878         /* There is a pte slot for 'address' in 'mm'. */
879         return 0;
880 }
881
882
883 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
884                 unsigned long start, int len, int write, int force,
885                 struct page **pages, struct vm_area_struct **vmas)
886 {
887         int i;
888         unsigned int flags;
889
890         /* 
891          * Require read or write permissions.
892          * If 'force' is set, we only require the "MAY" flags.
893          */
894         flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
895         flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
896         i = 0;
897
898         do {
899                 struct vm_area_struct * vma;
900
901                 vma = find_extend_vma(mm, start);
902                 if (!vma && in_gate_area(tsk, start)) {
903                         unsigned long pg = start & PAGE_MASK;
904                         struct vm_area_struct *gate_vma = get_gate_vma(tsk);
905                         pgd_t *pgd;
906                         pud_t *pud;
907                         pmd_t *pmd;
908                         pte_t *pte;
909                         if (write) /* user gate pages are read-only */
910                                 return i ? : -EFAULT;
911                         if (pg > TASK_SIZE)
912                                 pgd = pgd_offset_k(pg);
913                         else
914                                 pgd = pgd_offset_gate(mm, pg);
915                         BUG_ON(pgd_none(*pgd));
916                         pud = pud_offset(pgd, pg);
917                         BUG_ON(pud_none(*pud));
918                         pmd = pmd_offset(pud, pg);
919                         BUG_ON(pmd_none(*pmd));
920                         pte = pte_offset_map(pmd, pg);
921                         BUG_ON(pte_none(*pte));
922                         if (pages) {
923                                 pages[i] = pte_page(*pte);
924                                 get_page(pages[i]);
925                         }
926                         pte_unmap(pte);
927                         if (vmas)
928                                 vmas[i] = gate_vma;
929                         i++;
930                         start += PAGE_SIZE;
931                         len--;
932                         continue;
933                 }
934
935                 if (!vma || (vma->vm_flags & VM_IO)
936                                 || !(flags & vma->vm_flags))
937                         return i ? : -EFAULT;
938
939                 if (is_vm_hugetlb_page(vma)) {
940                         i = follow_hugetlb_page(mm, vma, pages, vmas,
941                                                 &start, &len, i);
942                         continue;
943                 }
944                 spin_lock(&mm->page_table_lock);
945                 do {
946                         struct page *map;
947                         int lookup_write = write;
948
949                         cond_resched_lock(&mm->page_table_lock);
950                         while (!(map = follow_page(mm, start, lookup_write))) {
951                                 /*
952                                  * Shortcut for anonymous pages. We don't want
953                                  * to force the creation of pages tables for
954                                  * insanly big anonymously mapped areas that
955                                  * nobody touched so far. This is important
956                                  * for doing a core dump for these mappings.
957                                  */
958                                 if (!lookup_write &&
959                                     untouched_anonymous_page(mm,vma,start)) {
960                                         map = ZERO_PAGE(start);
961                                         break;
962                                 }
963                                 spin_unlock(&mm->page_table_lock);
964                                 switch (handle_mm_fault(mm,vma,start,write)) {
965                                 case VM_FAULT_MINOR:
966                                         tsk->min_flt++;
967                                         break;
968                                 case VM_FAULT_MAJOR:
969                                         tsk->maj_flt++;
970                                         break;
971                                 case VM_FAULT_SIGBUS:
972                                         return i ? i : -EFAULT;
973                                 case VM_FAULT_OOM:
974                                         return i ? i : -ENOMEM;
975                                 default:
976                                         BUG();
977                                 }
978                                 /*
979                                  * Now that we have performed a write fault
980                                  * and surely no longer have a shared page we
981                                  * shouldn't write, we shouldn't ignore an
982                                  * unwritable page in the page table if
983                                  * we are forcing write access.
984                                  */
985                                 lookup_write = write && !force;
986                                 spin_lock(&mm->page_table_lock);
987                         }
988                         if (pages) {
989                                 pages[i] = get_page_map(map);
990                                 if (!pages[i]) {
991                                         spin_unlock(&mm->page_table_lock);
992                                         while (i--)
993                                                 page_cache_release(pages[i]);
994                                         i = -EFAULT;
995                                         goto out;
996                                 }
997                                 flush_dcache_page(pages[i]);
998                                 if (!PageReserved(pages[i]))
999                                         page_cache_get(pages[i]);
1000                         }
1001                         if (vmas)
1002                                 vmas[i] = vma;
1003                         i++;
1004                         start += PAGE_SIZE;
1005                         len--;
1006                 } while(len && start < vma->vm_end);
1007                 spin_unlock(&mm->page_table_lock);
1008         } while(len);
1009 out:
1010         return i;
1011 }
1012
1013 EXPORT_SYMBOL(get_user_pages);
1014
1015 static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1016                         unsigned long addr, unsigned long end, pgprot_t prot)
1017 {
1018         pte_t *pte;
1019
1020         pte = pte_alloc_map(mm, pmd, addr);
1021         if (!pte)
1022                 return -ENOMEM;
1023         do {
1024                 pte_t zero_pte = pte_wrprotect(mk_pte(ZERO_PAGE(addr), prot));
1025                 BUG_ON(!pte_none(*pte));
1026                 set_pte_at(mm, addr, pte, zero_pte);
1027         } while (pte++, addr += PAGE_SIZE, addr != end);
1028         pte_unmap(pte - 1);
1029         return 0;
1030 }
1031
1032 static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud,
1033                         unsigned long addr, unsigned long end, pgprot_t prot)
1034 {
1035         pmd_t *pmd;
1036         unsigned long next;
1037
1038         pmd = pmd_alloc(mm, pud, addr);
1039         if (!pmd)
1040                 return -ENOMEM;
1041         do {
1042                 next = pmd_addr_end(addr, end);
1043                 if (zeromap_pte_range(mm, pmd, addr, next, prot))
1044                         return -ENOMEM;
1045         } while (pmd++, addr = next, addr != end);
1046         return 0;
1047 }
1048
1049 static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1050                         unsigned long addr, unsigned long end, pgprot_t prot)
1051 {
1052         pud_t *pud;
1053         unsigned long next;
1054
1055         pud = pud_alloc(mm, pgd, addr);
1056         if (!pud)
1057                 return -ENOMEM;
1058         do {
1059                 next = pud_addr_end(addr, end);
1060                 if (zeromap_pmd_range(mm, pud, addr, next, prot))
1061                         return -ENOMEM;
1062         } while (pud++, addr = next, addr != end);
1063         return 0;
1064 }
1065
1066 int zeromap_page_range(struct vm_area_struct *vma,
1067                         unsigned long addr, unsigned long size, pgprot_t prot)
1068 {
1069         pgd_t *pgd;
1070         unsigned long next;
1071         unsigned long end = addr + size;
1072         struct mm_struct *mm = vma->vm_mm;
1073         int err;
1074
1075         BUG_ON(addr >= end);
1076         pgd = pgd_offset(mm, addr);
1077         flush_cache_range(vma, addr, end);
1078         spin_lock(&mm->page_table_lock);
1079         do {
1080                 next = pgd_addr_end(addr, end);
1081                 err = zeromap_pud_range(mm, pgd, addr, next, prot);
1082                 if (err)
1083                         break;
1084         } while (pgd++, addr = next, addr != end);
1085         spin_unlock(&mm->page_table_lock);
1086         return err;
1087 }
1088
1089 /*
1090  * maps a range of physical memory into the requested pages. the old
1091  * mappings are removed. any references to nonexistent pages results
1092  * in null mappings (currently treated as "copy-on-access")
1093  */
1094 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1095                         unsigned long addr, unsigned long end,
1096                         unsigned long pfn, pgprot_t prot)
1097 {
1098         pte_t *pte;
1099
1100         pte = pte_alloc_map(mm, pmd, addr);
1101         if (!pte)
1102                 return -ENOMEM;
1103         do {
1104                 BUG_ON(!pte_none(*pte));
1105                 if (!pfn_valid(pfn) || PageReserved(pfn_to_page(pfn)))
1106                         set_pte_at(mm, addr, pte, pfn_pte(pfn, prot));
1107                 pfn++;
1108         } while (pte++, addr += PAGE_SIZE, addr != end);
1109         pte_unmap(pte - 1);
1110         return 0;
1111 }
1112
1113 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1114                         unsigned long addr, unsigned long end,
1115                         unsigned long pfn, pgprot_t prot)
1116 {
1117         pmd_t *pmd;
1118         unsigned long next;
1119
1120         pfn -= addr >> PAGE_SHIFT;
1121         pmd = pmd_alloc(mm, pud, addr);
1122         if (!pmd)
1123                 return -ENOMEM;
1124         do {
1125                 next = pmd_addr_end(addr, end);
1126                 if (remap_pte_range(mm, pmd, addr, next,
1127                                 pfn + (addr >> PAGE_SHIFT), prot))
1128                         return -ENOMEM;
1129         } while (pmd++, addr = next, addr != end);
1130         return 0;
1131 }
1132
1133 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1134                         unsigned long addr, unsigned long end,
1135                         unsigned long pfn, pgprot_t prot)
1136 {
1137         pud_t *pud;
1138         unsigned long next;
1139
1140         pfn -= addr >> PAGE_SHIFT;
1141         pud = pud_alloc(mm, pgd, addr);
1142         if (!pud)
1143                 return -ENOMEM;
1144         do {
1145                 next = pud_addr_end(addr, end);
1146                 if (remap_pmd_range(mm, pud, addr, next,
1147                                 pfn + (addr >> PAGE_SHIFT), prot))
1148                         return -ENOMEM;
1149         } while (pud++, addr = next, addr != end);
1150         return 0;
1151 }
1152
1153 /*  Note: this is only safe if the mm semaphore is held when called. */
1154 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1155                     unsigned long pfn, unsigned long size, pgprot_t prot)
1156 {
1157         pgd_t *pgd;
1158         unsigned long next;
1159         unsigned long end = addr + size;
1160         struct mm_struct *mm = vma->vm_mm;
1161         int err;
1162
1163         /*
1164          * Physically remapped pages are special. Tell the
1165          * rest of the world about it:
1166          *   VM_IO tells people not to look at these pages
1167          *      (accesses can have side effects).
1168          *   VM_RESERVED tells swapout not to try to touch
1169          *      this region.
1170          */
1171         vma->vm_flags |= VM_IO | VM_RESERVED;
1172
1173         BUG_ON(addr >= end);
1174         pfn -= addr >> PAGE_SHIFT;
1175         pgd = pgd_offset(mm, addr);
1176         flush_cache_range(vma, addr, end);
1177         spin_lock(&mm->page_table_lock);
1178         do {
1179                 next = pgd_addr_end(addr, end);
1180                 err = remap_pud_range(mm, pgd, addr, next,
1181                                 pfn + (addr >> PAGE_SHIFT), prot);
1182                 if (err)
1183                         break;
1184         } while (pgd++, addr = next, addr != end);
1185         spin_unlock(&mm->page_table_lock);
1186         return err;
1187 }
1188 EXPORT_SYMBOL(remap_pfn_range);
1189
1190 /*
1191  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
1192  * servicing faults for write access.  In the normal case, do always want
1193  * pte_mkwrite.  But get_user_pages can cause write faults for mappings
1194  * that do not have writing enabled, when used by access_process_vm.
1195  */
1196 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
1197 {
1198         if (likely(vma->vm_flags & VM_WRITE))
1199                 pte = pte_mkwrite(pte);
1200         return pte;
1201 }
1202
1203 /*
1204  * We hold the mm semaphore for reading and vma->vm_mm->page_table_lock
1205  */
1206 static inline void break_cow(struct vm_area_struct * vma, struct page * new_page, unsigned long address, 
1207                 pte_t *page_table)
1208 {
1209         pte_t entry;
1210
1211         entry = maybe_mkwrite(pte_mkdirty(mk_pte(new_page, vma->vm_page_prot)),
1212                               vma);
1213         ptep_establish(vma, address, page_table, entry);
1214         update_mmu_cache(vma, address, entry);
1215         lazy_mmu_prot_update(entry);
1216 }
1217
1218 /*
1219  * This routine handles present pages, when users try to write
1220  * to a shared page. It is done by copying the page to a new address
1221  * and decrementing the shared-page counter for the old page.
1222  *
1223  * Goto-purists beware: the only reason for goto's here is that it results
1224  * in better assembly code.. The "default" path will see no jumps at all.
1225  *
1226  * Note that this routine assumes that the protection checks have been
1227  * done by the caller (the low-level page fault routine in most cases).
1228  * Thus we can safely just mark it writable once we've done any necessary
1229  * COW.
1230  *
1231  * We also mark the page dirty at this point even though the page will
1232  * change only once the write actually happens. This avoids a few races,
1233  * and potentially makes it more efficient.
1234  *
1235  * We hold the mm semaphore and the page_table_lock on entry and exit
1236  * with the page_table_lock released.
1237  */
1238 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma,
1239         unsigned long address, pte_t *page_table, pmd_t *pmd, pte_t pte)
1240 {
1241         struct page *old_page, *new_page;
1242         unsigned long pfn = pte_pfn(pte);
1243         pte_t entry;
1244
1245         if (unlikely(!pfn_valid(pfn))) {
1246                 /*
1247                  * This should really halt the system so it can be debugged or
1248                  * at least the kernel stops what it's doing before it corrupts
1249                  * data, but for the moment just pretend this is OOM.
1250                  */
1251                 pte_unmap(page_table);
1252                 printk(KERN_ERR "do_wp_page: bogus page at address %08lx\n",
1253                                 address);
1254                 spin_unlock(&mm->page_table_lock);
1255                 return VM_FAULT_OOM;
1256         }
1257         old_page = pfn_to_page(pfn);
1258
1259         if (!TestSetPageLocked(old_page)) {
1260                 int reuse = can_share_swap_page(old_page);
1261                 unlock_page(old_page);
1262                 if (reuse) {
1263                         flush_cache_page(vma, address, pfn);
1264                         entry = maybe_mkwrite(pte_mkyoung(pte_mkdirty(pte)),
1265                                               vma);
1266                         ptep_set_access_flags(vma, address, page_table, entry, 1);
1267                         update_mmu_cache(vma, address, entry);
1268                         lazy_mmu_prot_update(entry);
1269                         pte_unmap(page_table);
1270                         spin_unlock(&mm->page_table_lock);
1271                         return VM_FAULT_MINOR;
1272                 }
1273         }
1274         pte_unmap(page_table);
1275
1276         /*
1277          * Ok, we need to copy. Oh, well..
1278          */
1279         if (!PageReserved(old_page))
1280                 page_cache_get(old_page);
1281         spin_unlock(&mm->page_table_lock);
1282
1283         if (unlikely(anon_vma_prepare(vma)))
1284                 goto no_new_page;
1285         if (old_page == ZERO_PAGE(address)) {
1286                 new_page = alloc_zeroed_user_highpage(vma, address);
1287                 if (!new_page)
1288                         goto no_new_page;
1289         } else {
1290                 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1291                 if (!new_page)
1292                         goto no_new_page;
1293                 copy_user_highpage(new_page, old_page, address);
1294         }
1295         /*
1296          * Re-check the pte - we dropped the lock
1297          */
1298         spin_lock(&mm->page_table_lock);
1299         page_table = pte_offset_map(pmd, address);
1300         if (likely(pte_same(*page_table, pte))) {
1301                 if (PageAnon(old_page))
1302                         dec_mm_counter(mm, anon_rss);
1303                 if (PageReserved(old_page))
1304                         inc_mm_counter(mm, rss);
1305                 else
1306                         page_remove_rmap(old_page);
1307                 flush_cache_page(vma, address, pfn);
1308                 break_cow(vma, new_page, address, page_table);
1309                 lru_cache_add_active(new_page);
1310                 page_add_anon_rmap(new_page, vma, address);
1311
1312                 /* Free the old page.. */
1313                 new_page = old_page;
1314         }
1315         pte_unmap(page_table);
1316         page_cache_release(new_page);
1317         page_cache_release(old_page);
1318         spin_unlock(&mm->page_table_lock);
1319         return VM_FAULT_MINOR;
1320
1321 no_new_page:
1322         page_cache_release(old_page);
1323         return VM_FAULT_OOM;
1324 }
1325
1326 /*
1327  * Helper functions for unmap_mapping_range().
1328  *
1329  * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
1330  *
1331  * We have to restart searching the prio_tree whenever we drop the lock,
1332  * since the iterator is only valid while the lock is held, and anyway
1333  * a later vma might be split and reinserted earlier while lock dropped.
1334  *
1335  * The list of nonlinear vmas could be handled more efficiently, using
1336  * a placeholder, but handle it in the same way until a need is shown.
1337  * It is important to search the prio_tree before nonlinear list: a vma
1338  * may become nonlinear and be shifted from prio_tree to nonlinear list
1339  * while the lock is dropped; but never shifted from list to prio_tree.
1340  *
1341  * In order to make forward progress despite restarting the search,
1342  * vm_truncate_count is used to mark a vma as now dealt with, so we can
1343  * quickly skip it next time around.  Since the prio_tree search only
1344  * shows us those vmas affected by unmapping the range in question, we
1345  * can't efficiently keep all vmas in step with mapping->truncate_count:
1346  * so instead reset them all whenever it wraps back to 0 (then go to 1).
1347  * mapping->truncate_count and vma->vm_truncate_count are protected by
1348  * i_mmap_lock.
1349  *
1350  * In order to make forward progress despite repeatedly restarting some
1351  * large vma, note the break_addr set by unmap_vmas when it breaks out:
1352  * and restart from that address when we reach that vma again.  It might
1353  * have been split or merged, shrunk or extended, but never shifted: so
1354  * restart_addr remains valid so long as it remains in the vma's range.
1355  * unmap_mapping_range forces truncate_count to leap over page-aligned
1356  * values so we can save vma's restart_addr in its truncate_count field.
1357  */
1358 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
1359
1360 static void reset_vma_truncate_counts(struct address_space *mapping)
1361 {
1362         struct vm_area_struct *vma;
1363         struct prio_tree_iter iter;
1364
1365         vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
1366                 vma->vm_truncate_count = 0;
1367         list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1368                 vma->vm_truncate_count = 0;
1369 }
1370
1371 static int unmap_mapping_range_vma(struct vm_area_struct *vma,
1372                 unsigned long start_addr, unsigned long end_addr,
1373                 struct zap_details *details)
1374 {
1375         unsigned long restart_addr;
1376         int need_break;
1377
1378 again:
1379         restart_addr = vma->vm_truncate_count;
1380         if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
1381                 start_addr = restart_addr;
1382                 if (start_addr >= end_addr) {
1383                         /* Top of vma has been split off since last time */
1384                         vma->vm_truncate_count = details->truncate_count;
1385                         return 0;
1386                 }
1387         }
1388
1389         details->break_addr = end_addr;
1390         zap_page_range(vma, start_addr, end_addr - start_addr, details);
1391
1392         /*
1393          * We cannot rely on the break test in unmap_vmas:
1394          * on the one hand, we don't want to restart our loop
1395          * just because that broke out for the page_table_lock;
1396          * on the other hand, it does no test when vma is small.
1397          */
1398         need_break = need_resched() ||
1399                         need_lockbreak(details->i_mmap_lock);
1400
1401         if (details->break_addr >= end_addr) {
1402                 /* We have now completed this vma: mark it so */
1403                 vma->vm_truncate_count = details->truncate_count;
1404                 if (!need_break)
1405                         return 0;
1406         } else {
1407                 /* Note restart_addr in vma's truncate_count field */
1408                 vma->vm_truncate_count = details->break_addr;
1409                 if (!need_break)
1410                         goto again;
1411         }
1412
1413         spin_unlock(details->i_mmap_lock);
1414         cond_resched();
1415         spin_lock(details->i_mmap_lock);
1416         return -EINTR;
1417 }
1418
1419 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
1420                                             struct zap_details *details)
1421 {
1422         struct vm_area_struct *vma;
1423         struct prio_tree_iter iter;
1424         pgoff_t vba, vea, zba, zea;
1425
1426 restart:
1427         vma_prio_tree_foreach(vma, &iter, root,
1428                         details->first_index, details->last_index) {
1429                 /* Skip quickly over those we have already dealt with */
1430                 if (vma->vm_truncate_count == details->truncate_count)
1431                         continue;
1432
1433                 vba = vma->vm_pgoff;
1434                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
1435                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
1436                 zba = details->first_index;
1437                 if (zba < vba)
1438                         zba = vba;
1439                 zea = details->last_index;
1440                 if (zea > vea)
1441                         zea = vea;
1442
1443                 if (unmap_mapping_range_vma(vma,
1444                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
1445                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
1446                                 details) < 0)
1447                         goto restart;
1448         }
1449 }
1450
1451 static inline void unmap_mapping_range_list(struct list_head *head,
1452                                             struct zap_details *details)
1453 {
1454         struct vm_area_struct *vma;
1455
1456         /*
1457          * In nonlinear VMAs there is no correspondence between virtual address
1458          * offset and file offset.  So we must perform an exhaustive search
1459          * across *all* the pages in each nonlinear VMA, not just the pages
1460          * whose virtual address lies outside the file truncation point.
1461          */
1462 restart:
1463         list_for_each_entry(vma, head, shared.vm_set.list) {
1464                 /* Skip quickly over those we have already dealt with */
1465                 if (vma->vm_truncate_count == details->truncate_count)
1466                         continue;
1467                 details->nonlinear_vma = vma;
1468                 if (unmap_mapping_range_vma(vma, vma->vm_start,
1469                                         vma->vm_end, details) < 0)
1470                         goto restart;
1471         }
1472 }
1473
1474 /**
1475  * unmap_mapping_range - unmap the portion of all mmaps
1476  * in the specified address_space corresponding to the specified
1477  * page range in the underlying file.
1478  * @address_space: the address space containing mmaps to be unmapped.
1479  * @holebegin: byte in first page to unmap, relative to the start of
1480  * the underlying file.  This will be rounded down to a PAGE_SIZE
1481  * boundary.  Note that this is different from vmtruncate(), which
1482  * must keep the partial page.  In contrast, we must get rid of
1483  * partial pages.
1484  * @holelen: size of prospective hole in bytes.  This will be rounded
1485  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
1486  * end of the file.
1487  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
1488  * but 0 when invalidating pagecache, don't throw away private data.
1489  */
1490 void unmap_mapping_range(struct address_space *mapping,
1491                 loff_t const holebegin, loff_t const holelen, int even_cows)
1492 {
1493         struct zap_details details;
1494         pgoff_t hba = holebegin >> PAGE_SHIFT;
1495         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1496
1497         /* Check for overflow. */
1498         if (sizeof(holelen) > sizeof(hlen)) {
1499                 long long holeend =
1500                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1501                 if (holeend & ~(long long)ULONG_MAX)
1502                         hlen = ULONG_MAX - hba + 1;
1503         }
1504
1505         details.check_mapping = even_cows? NULL: mapping;
1506         details.nonlinear_vma = NULL;
1507         details.first_index = hba;
1508         details.last_index = hba + hlen - 1;
1509         if (details.last_index < details.first_index)
1510                 details.last_index = ULONG_MAX;
1511         details.i_mmap_lock = &mapping->i_mmap_lock;
1512
1513         spin_lock(&mapping->i_mmap_lock);
1514
1515         /* serialize i_size write against truncate_count write */
1516         smp_wmb();
1517         /* Protect against page faults, and endless unmapping loops */
1518         mapping->truncate_count++;
1519         /*
1520          * For archs where spin_lock has inclusive semantics like ia64
1521          * this smp_mb() will prevent to read pagetable contents
1522          * before the truncate_count increment is visible to
1523          * other cpus.
1524          */
1525         smp_mb();
1526         if (unlikely(is_restart_addr(mapping->truncate_count))) {
1527                 if (mapping->truncate_count == 0)
1528                         reset_vma_truncate_counts(mapping);
1529                 mapping->truncate_count++;
1530         }
1531         details.truncate_count = mapping->truncate_count;
1532
1533         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
1534                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
1535         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
1536                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
1537         spin_unlock(&mapping->i_mmap_lock);
1538 }
1539 EXPORT_SYMBOL(unmap_mapping_range);
1540
1541 /*
1542  * Handle all mappings that got truncated by a "truncate()"
1543  * system call.
1544  *
1545  * NOTE! We have to be ready to update the memory sharing
1546  * between the file and the memory map for a potential last
1547  * incomplete page.  Ugly, but necessary.
1548  */
1549 int vmtruncate(struct inode * inode, loff_t offset)
1550 {
1551         struct address_space *mapping = inode->i_mapping;
1552         unsigned long limit;
1553
1554         if (inode->i_size < offset)
1555                 goto do_expand;
1556         /*
1557          * truncation of in-use swapfiles is disallowed - it would cause
1558          * subsequent swapout to scribble on the now-freed blocks.
1559          */
1560         if (IS_SWAPFILE(inode))
1561                 goto out_busy;
1562         i_size_write(inode, offset);
1563         unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
1564         truncate_inode_pages(mapping, offset);
1565         goto out_truncate;
1566
1567 do_expand:
1568         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1569         if (limit != RLIM_INFINITY && offset > limit)
1570                 goto out_sig;
1571         if (offset > inode->i_sb->s_maxbytes)
1572                 goto out_big;
1573         i_size_write(inode, offset);
1574
1575 out_truncate:
1576         if (inode->i_op && inode->i_op->truncate)
1577                 inode->i_op->truncate(inode);
1578         return 0;
1579 out_sig:
1580         send_sig(SIGXFSZ, current, 0);
1581 out_big:
1582         return -EFBIG;
1583 out_busy:
1584         return -ETXTBSY;
1585 }
1586
1587 EXPORT_SYMBOL(vmtruncate);
1588
1589 /* 
1590  * Primitive swap readahead code. We simply read an aligned block of
1591  * (1 << page_cluster) entries in the swap area. This method is chosen
1592  * because it doesn't cost us any seek time.  We also make sure to queue
1593  * the 'original' request together with the readahead ones...  
1594  *
1595  * This has been extended to use the NUMA policies from the mm triggering
1596  * the readahead.
1597  *
1598  * Caller must hold down_read on the vma->vm_mm if vma is not NULL.
1599  */
1600 void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma)
1601 {
1602 #ifdef CONFIG_NUMA
1603         struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL;
1604 #endif
1605         int i, num;
1606         struct page *new_page;
1607         unsigned long offset;
1608
1609         /*
1610          * Get the number of handles we should do readahead io to.
1611          */
1612         num = valid_swaphandles(entry, &offset);
1613         for (i = 0; i < num; offset++, i++) {
1614                 /* Ok, do the async read-ahead now */
1615                 new_page = read_swap_cache_async(swp_entry(swp_type(entry),
1616                                                            offset), vma, addr);
1617                 if (!new_page)
1618                         break;
1619                 page_cache_release(new_page);
1620 #ifdef CONFIG_NUMA
1621                 /*
1622                  * Find the next applicable VMA for the NUMA policy.
1623                  */
1624                 addr += PAGE_SIZE;
1625                 if (addr == 0)
1626                         vma = NULL;
1627                 if (vma) {
1628                         if (addr >= vma->vm_end) {
1629                                 vma = next_vma;
1630                                 next_vma = vma ? vma->vm_next : NULL;
1631                         }
1632                         if (vma && addr < vma->vm_start)
1633                                 vma = NULL;
1634                 } else {
1635                         if (next_vma && addr >= next_vma->vm_start) {
1636                                 vma = next_vma;
1637                                 next_vma = vma->vm_next;
1638                         }
1639                 }
1640 #endif
1641         }
1642         lru_add_drain();        /* Push any new pages onto the LRU now */
1643 }
1644
1645 /*
1646  * We hold the mm semaphore and the page_table_lock on entry and
1647  * should release the pagetable lock on exit..
1648  */
1649 static int do_swap_page(struct mm_struct * mm,
1650         struct vm_area_struct * vma, unsigned long address,
1651         pte_t *page_table, pmd_t *pmd, pte_t orig_pte, int write_access)
1652 {
1653         struct page *page;
1654         swp_entry_t entry = pte_to_swp_entry(orig_pte);
1655         pte_t pte;
1656         int ret = VM_FAULT_MINOR;
1657
1658         pte_unmap(page_table);
1659         spin_unlock(&mm->page_table_lock);
1660         page = lookup_swap_cache(entry);
1661         if (!page) {
1662                 swapin_readahead(entry, address, vma);
1663                 page = read_swap_cache_async(entry, vma, address);
1664                 if (!page) {
1665                         /*
1666                          * Back out if somebody else faulted in this pte while
1667                          * we released the page table lock.
1668                          */
1669                         spin_lock(&mm->page_table_lock);
1670                         page_table = pte_offset_map(pmd, address);
1671                         if (likely(pte_same(*page_table, orig_pte)))
1672                                 ret = VM_FAULT_OOM;
1673                         else
1674                                 ret = VM_FAULT_MINOR;
1675                         pte_unmap(page_table);
1676                         spin_unlock(&mm->page_table_lock);
1677                         goto out;
1678                 }
1679
1680                 /* Had to read the page from swap area: Major fault */
1681                 ret = VM_FAULT_MAJOR;
1682                 inc_page_state(pgmajfault);
1683                 grab_swap_token();
1684         }
1685
1686         mark_page_accessed(page);
1687         lock_page(page);
1688
1689         /*
1690          * Back out if somebody else faulted in this pte while we
1691          * released the page table lock.
1692          */
1693         spin_lock(&mm->page_table_lock);
1694         page_table = pte_offset_map(pmd, address);
1695         if (unlikely(!pte_same(*page_table, orig_pte))) {
1696                 pte_unmap(page_table);
1697                 spin_unlock(&mm->page_table_lock);
1698                 unlock_page(page);
1699                 page_cache_release(page);
1700                 ret = VM_FAULT_MINOR;
1701                 goto out;
1702         }
1703
1704         /* The page isn't present yet, go ahead with the fault. */
1705                 
1706         swap_free(entry);
1707         if (vm_swap_full())
1708                 remove_exclusive_swap_page(page);
1709
1710         inc_mm_counter(mm, rss);
1711         pte = mk_pte(page, vma->vm_page_prot);
1712         if (write_access && can_share_swap_page(page)) {
1713                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
1714                 write_access = 0;
1715         }
1716         unlock_page(page);
1717
1718         flush_icache_page(vma, page);
1719         set_pte_at(mm, address, page_table, pte);
1720         page_add_anon_rmap(page, vma, address);
1721
1722         if (write_access) {
1723                 if (do_wp_page(mm, vma, address,
1724                                 page_table, pmd, pte) == VM_FAULT_OOM)
1725                         ret = VM_FAULT_OOM;
1726                 goto out;
1727         }
1728
1729         /* No need to invalidate - it was non-present before */
1730         update_mmu_cache(vma, address, pte);
1731         lazy_mmu_prot_update(pte);
1732         pte_unmap(page_table);
1733         spin_unlock(&mm->page_table_lock);
1734 out:
1735         return ret;
1736 }
1737
1738 /*
1739  * We are called with the MM semaphore and page_table_lock
1740  * spinlock held to protect against concurrent faults in
1741  * multithreaded programs. 
1742  */
1743 static int
1744 do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
1745                 pte_t *page_table, pmd_t *pmd, int write_access,
1746                 unsigned long addr)
1747 {
1748         pte_t entry;
1749         struct page * page = ZERO_PAGE(addr);
1750
1751         /* Read-only mapping of ZERO_PAGE. */
1752         entry = pte_wrprotect(mk_pte(ZERO_PAGE(addr), vma->vm_page_prot));
1753
1754         /* ..except if it's a write access */
1755         if (write_access) {
1756                 /* Allocate our own private page. */
1757                 pte_unmap(page_table);
1758                 spin_unlock(&mm->page_table_lock);
1759
1760                 if (unlikely(anon_vma_prepare(vma)))
1761                         goto no_mem;
1762                 page = alloc_zeroed_user_highpage(vma, addr);
1763                 if (!page)
1764                         goto no_mem;
1765
1766                 spin_lock(&mm->page_table_lock);
1767                 page_table = pte_offset_map(pmd, addr);
1768
1769                 if (!pte_none(*page_table)) {
1770                         pte_unmap(page_table);
1771                         page_cache_release(page);
1772                         spin_unlock(&mm->page_table_lock);
1773                         goto out;
1774                 }
1775                 inc_mm_counter(mm, rss);
1776                 entry = maybe_mkwrite(pte_mkdirty(mk_pte(page,
1777                                                          vma->vm_page_prot)),
1778                                       vma);
1779                 lru_cache_add_active(page);
1780                 SetPageReferenced(page);
1781                 page_add_anon_rmap(page, vma, addr);
1782         }
1783
1784         set_pte_at(mm, addr, page_table, entry);
1785         pte_unmap(page_table);
1786
1787         /* No need to invalidate - it was non-present before */
1788         update_mmu_cache(vma, addr, entry);
1789         lazy_mmu_prot_update(entry);
1790         spin_unlock(&mm->page_table_lock);
1791 out:
1792         return VM_FAULT_MINOR;
1793 no_mem:
1794         return VM_FAULT_OOM;
1795 }
1796
1797 /*
1798  * do_no_page() tries to create a new page mapping. It aggressively
1799  * tries to share with existing pages, but makes a separate copy if
1800  * the "write_access" parameter is true in order to avoid the next
1801  * page fault.
1802  *
1803  * As this is called only for pages that do not currently exist, we
1804  * do not need to flush old virtual caches or the TLB.
1805  *
1806  * This is called with the MM semaphore held and the page table
1807  * spinlock held. Exit with the spinlock released.
1808  */
1809 static int
1810 do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
1811         unsigned long address, int write_access, pte_t *page_table, pmd_t *pmd)
1812 {
1813         struct page * new_page;
1814         struct address_space *mapping = NULL;
1815         pte_t entry;
1816         unsigned int sequence = 0;
1817         int ret = VM_FAULT_MINOR;
1818         int anon = 0;
1819
1820         if (!vma->vm_ops || !vma->vm_ops->nopage)
1821                 return do_anonymous_page(mm, vma, page_table,
1822                                         pmd, write_access, address);
1823         pte_unmap(page_table);
1824         spin_unlock(&mm->page_table_lock);
1825
1826         if (vma->vm_file) {
1827                 mapping = vma->vm_file->f_mapping;
1828                 sequence = mapping->truncate_count;
1829                 smp_rmb(); /* serializes i_size against truncate_count */
1830         }
1831 retry:
1832         cond_resched();
1833         new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret);
1834         /*
1835          * No smp_rmb is needed here as long as there's a full
1836          * spin_lock/unlock sequence inside the ->nopage callback
1837          * (for the pagecache lookup) that acts as an implicit
1838          * smp_mb() and prevents the i_size read to happen
1839          * after the next truncate_count read.
1840          */
1841
1842         /* no page was available -- either SIGBUS or OOM */
1843         if (new_page == NOPAGE_SIGBUS)
1844                 return VM_FAULT_SIGBUS;
1845         if (new_page == NOPAGE_OOM)
1846                 return VM_FAULT_OOM;
1847
1848         /*
1849          * Should we do an early C-O-W break?
1850          */
1851         if (write_access && !(vma->vm_flags & VM_SHARED)) {
1852                 struct page *page;
1853
1854                 if (unlikely(anon_vma_prepare(vma)))
1855                         goto oom;
1856                 page = alloc_page_vma(GFP_HIGHUSER, vma, address);
1857                 if (!page)
1858                         goto oom;
1859                 copy_user_highpage(page, new_page, address);
1860                 page_cache_release(new_page);
1861                 new_page = page;
1862                 anon = 1;
1863         }
1864
1865         spin_lock(&mm->page_table_lock);
1866         /*
1867          * For a file-backed vma, someone could have truncated or otherwise
1868          * invalidated this page.  If unmap_mapping_range got called,
1869          * retry getting the page.
1870          */
1871         if (mapping && unlikely(sequence != mapping->truncate_count)) {
1872                 sequence = mapping->truncate_count;
1873                 spin_unlock(&mm->page_table_lock);
1874                 page_cache_release(new_page);
1875                 goto retry;
1876         }
1877         page_table = pte_offset_map(pmd, address);
1878
1879         /*
1880          * This silly early PAGE_DIRTY setting removes a race
1881          * due to the bad i386 page protection. But it's valid
1882          * for other architectures too.
1883          *
1884          * Note that if write_access is true, we either now have
1885          * an exclusive copy of the page, or this is a shared mapping,
1886          * so we can make it writable and dirty to avoid having to
1887          * handle that later.
1888          */
1889         /* Only go through if we didn't race with anybody else... */
1890         if (pte_none(*page_table)) {
1891                 if (!PageReserved(new_page))
1892                         inc_mm_counter(mm, rss);
1893
1894                 flush_icache_page(vma, new_page);
1895                 entry = mk_pte(new_page, vma->vm_page_prot);
1896                 if (write_access)
1897                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1898                 set_pte_at(mm, address, page_table, entry);
1899                 if (anon) {
1900                         lru_cache_add_active(new_page);
1901                         page_add_anon_rmap(new_page, vma, address);
1902                 } else
1903                         page_add_file_rmap(new_page);
1904                 pte_unmap(page_table);
1905         } else {
1906                 /* One of our sibling threads was faster, back out. */
1907                 pte_unmap(page_table);
1908                 page_cache_release(new_page);
1909                 spin_unlock(&mm->page_table_lock);
1910                 goto out;
1911         }
1912
1913         /* no need to invalidate: a not-present page shouldn't be cached */
1914         update_mmu_cache(vma, address, entry);
1915         lazy_mmu_prot_update(entry);
1916         spin_unlock(&mm->page_table_lock);
1917 out:
1918         return ret;
1919 oom:
1920         page_cache_release(new_page);
1921         ret = VM_FAULT_OOM;
1922         goto out;
1923 }
1924
1925 /*
1926  * Fault of a previously existing named mapping. Repopulate the pte
1927  * from the encoded file_pte if possible. This enables swappable
1928  * nonlinear vmas.
1929  */
1930 static int do_file_page(struct mm_struct * mm, struct vm_area_struct * vma,
1931         unsigned long address, int write_access, pte_t *pte, pmd_t *pmd)
1932 {
1933         unsigned long pgoff;
1934         int err;
1935
1936         BUG_ON(!vma->vm_ops || !vma->vm_ops->nopage);
1937         /*
1938          * Fall back to the linear mapping if the fs does not support
1939          * ->populate:
1940          */
1941         if (!vma->vm_ops || !vma->vm_ops->populate || 
1942                         (write_access && !(vma->vm_flags & VM_SHARED))) {
1943                 pte_clear(mm, address, pte);
1944                 return do_no_page(mm, vma, address, write_access, pte, pmd);
1945         }
1946
1947         pgoff = pte_to_pgoff(*pte);
1948
1949         pte_unmap(pte);
1950         spin_unlock(&mm->page_table_lock);
1951
1952         err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, vma->vm_page_prot, pgoff, 0);
1953         if (err == -ENOMEM)
1954                 return VM_FAULT_OOM;
1955         if (err)
1956                 return VM_FAULT_SIGBUS;
1957         return VM_FAULT_MAJOR;
1958 }
1959
1960 /*
1961  * These routines also need to handle stuff like marking pages dirty
1962  * and/or accessed for architectures that don't do it in hardware (most
1963  * RISC architectures).  The early dirtying is also good on the i386.
1964  *
1965  * There is also a hook called "update_mmu_cache()" that architectures
1966  * with external mmu caches can use to update those (ie the Sparc or
1967  * PowerPC hashed page tables that act as extended TLBs).
1968  *
1969  * Note the "page_table_lock". It is to protect against kswapd removing
1970  * pages from under us. Note that kswapd only ever _removes_ pages, never
1971  * adds them. As such, once we have noticed that the page is not present,
1972  * we can drop the lock early.
1973  *
1974  * The adding of pages is protected by the MM semaphore (which we hold),
1975  * so we don't need to worry about a page being suddenly been added into
1976  * our VM.
1977  *
1978  * We enter with the pagetable spinlock held, we are supposed to
1979  * release it when done.
1980  */
1981 static inline int handle_pte_fault(struct mm_struct *mm,
1982         struct vm_area_struct * vma, unsigned long address,
1983         int write_access, pte_t *pte, pmd_t *pmd)
1984 {
1985         pte_t entry;
1986
1987         entry = *pte;
1988         if (!pte_present(entry)) {
1989                 /*
1990                  * If it truly wasn't present, we know that kswapd
1991                  * and the PTE updates will not touch it later. So
1992                  * drop the lock.
1993                  */
1994                 if (pte_none(entry))
1995                         return do_no_page(mm, vma, address, write_access, pte, pmd);
1996                 if (pte_file(entry))
1997                         return do_file_page(mm, vma, address, write_access, pte, pmd);
1998                 return do_swap_page(mm, vma, address, pte, pmd, entry, write_access);
1999         }
2000
2001         if (write_access) {
2002                 if (!pte_write(entry))
2003                         return do_wp_page(mm, vma, address, pte, pmd, entry);
2004
2005                 entry = pte_mkdirty(entry);
2006         }
2007         entry = pte_mkyoung(entry);
2008         ptep_set_access_flags(vma, address, pte, entry, write_access);
2009         update_mmu_cache(vma, address, entry);
2010         lazy_mmu_prot_update(entry);
2011         pte_unmap(pte);
2012         spin_unlock(&mm->page_table_lock);
2013         return VM_FAULT_MINOR;
2014 }
2015
2016 /*
2017  * By the time we get here, we already hold the mm semaphore
2018  */
2019 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma,
2020                 unsigned long address, int write_access)
2021 {
2022         pgd_t *pgd;
2023         pud_t *pud;
2024         pmd_t *pmd;
2025         pte_t *pte;
2026
2027         __set_current_state(TASK_RUNNING);
2028
2029         inc_page_state(pgfault);
2030
2031         if (is_vm_hugetlb_page(vma))
2032                 return VM_FAULT_SIGBUS; /* mapping truncation does this. */
2033
2034         /*
2035          * We need the page table lock to synchronize with kswapd
2036          * and the SMP-safe atomic PTE updates.
2037          */
2038         pgd = pgd_offset(mm, address);
2039         spin_lock(&mm->page_table_lock);
2040
2041         pud = pud_alloc(mm, pgd, address);
2042         if (!pud)
2043                 goto oom;
2044
2045         pmd = pmd_alloc(mm, pud, address);
2046         if (!pmd)
2047                 goto oom;
2048
2049         pte = pte_alloc_map(mm, pmd, address);
2050         if (!pte)
2051                 goto oom;
2052         
2053         return handle_pte_fault(mm, vma, address, write_access, pte, pmd);
2054
2055  oom:
2056         spin_unlock(&mm->page_table_lock);
2057         return VM_FAULT_OOM;
2058 }
2059
2060 #ifndef __PAGETABLE_PUD_FOLDED
2061 /*
2062  * Allocate page upper directory.
2063  *
2064  * We've already handled the fast-path in-line, and we own the
2065  * page table lock.
2066  */
2067 pud_t fastcall *__pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
2068 {
2069         pud_t *new;
2070
2071         spin_unlock(&mm->page_table_lock);
2072         new = pud_alloc_one(mm, address);
2073         spin_lock(&mm->page_table_lock);
2074         if (!new)
2075                 return NULL;
2076
2077         /*
2078          * Because we dropped the lock, we should re-check the
2079          * entry, as somebody else could have populated it..
2080          */
2081         if (pgd_present(*pgd)) {
2082                 pud_free(new);
2083                 goto out;
2084         }
2085         pgd_populate(mm, pgd, new);
2086  out:
2087         return pud_offset(pgd, address);
2088 }
2089 #endif /* __PAGETABLE_PUD_FOLDED */
2090
2091 #ifndef __PAGETABLE_PMD_FOLDED
2092 /*
2093  * Allocate page middle directory.
2094  *
2095  * We've already handled the fast-path in-line, and we own the
2096  * page table lock.
2097  */
2098 pmd_t fastcall *__pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
2099 {
2100         pmd_t *new;
2101
2102         spin_unlock(&mm->page_table_lock);
2103         new = pmd_alloc_one(mm, address);
2104         spin_lock(&mm->page_table_lock);
2105         if (!new)
2106                 return NULL;
2107
2108         /*
2109          * Because we dropped the lock, we should re-check the
2110          * entry, as somebody else could have populated it..
2111          */
2112 #ifndef __ARCH_HAS_4LEVEL_HACK
2113         if (pud_present(*pud)) {
2114                 pmd_free(new);
2115                 goto out;
2116         }
2117         pud_populate(mm, pud, new);
2118 #else
2119         if (pgd_present(*pud)) {
2120                 pmd_free(new);
2121                 goto out;
2122         }
2123         pgd_populate(mm, pud, new);
2124 #endif /* __ARCH_HAS_4LEVEL_HACK */
2125
2126  out:
2127         return pmd_offset(pud, address);
2128 }
2129 #endif /* __PAGETABLE_PMD_FOLDED */
2130
2131 int make_pages_present(unsigned long addr, unsigned long end)
2132 {
2133         int ret, len, write;
2134         struct vm_area_struct * vma;
2135
2136         vma = find_vma(current->mm, addr);
2137         if (!vma)
2138                 return -1;
2139         write = (vma->vm_flags & VM_WRITE) != 0;
2140         if (addr >= end)
2141                 BUG();
2142         if (end > vma->vm_end)
2143                 BUG();
2144         len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE;
2145         ret = get_user_pages(current, current->mm, addr,
2146                         len, write, 0, NULL, NULL);
2147         if (ret < 0)
2148                 return ret;
2149         return ret == len ? 0 : -1;
2150 }
2151
2152 /* 
2153  * Map a vmalloc()-space virtual address to the physical page.
2154  */
2155 struct page * vmalloc_to_page(void * vmalloc_addr)
2156 {
2157         unsigned long addr = (unsigned long) vmalloc_addr;
2158         struct page *page = NULL;
2159         pgd_t *pgd = pgd_offset_k(addr);
2160         pud_t *pud;
2161         pmd_t *pmd;
2162         pte_t *ptep, pte;
2163   
2164         if (!pgd_none(*pgd)) {
2165                 pud = pud_offset(pgd, addr);
2166                 if (!pud_none(*pud)) {
2167                         pmd = pmd_offset(pud, addr);
2168                         if (!pmd_none(*pmd)) {
2169                                 ptep = pte_offset_map(pmd, addr);
2170                                 pte = *ptep;
2171                                 if (pte_present(pte))
2172                                         page = pte_page(pte);
2173                                 pte_unmap(ptep);
2174                         }
2175                 }
2176         }
2177         return page;
2178 }
2179
2180 EXPORT_SYMBOL(vmalloc_to_page);
2181
2182 /*
2183  * Map a vmalloc()-space virtual address to the physical page frame number.
2184  */
2185 unsigned long vmalloc_to_pfn(void * vmalloc_addr)
2186 {
2187         return page_to_pfn(vmalloc_to_page(vmalloc_addr));
2188 }
2189
2190 EXPORT_SYMBOL(vmalloc_to_pfn);
2191
2192 /*
2193  * update_mem_hiwater
2194  *      - update per process rss and vm high water data
2195  */
2196 void update_mem_hiwater(struct task_struct *tsk)
2197 {
2198         if (tsk->mm) {
2199                 unsigned long rss = get_mm_counter(tsk->mm, rss);
2200
2201                 if (tsk->mm->hiwater_rss < rss)
2202                         tsk->mm->hiwater_rss = rss;
2203                 if (tsk->mm->hiwater_vm < tsk->mm->total_vm)
2204                         tsk->mm->hiwater_vm = tsk->mm->total_vm;
2205         }
2206 }
2207
2208 #if !defined(__HAVE_ARCH_GATE_AREA)
2209
2210 #if defined(AT_SYSINFO_EHDR)
2211 struct vm_area_struct gate_vma;
2212
2213 static int __init gate_vma_init(void)
2214 {
2215         gate_vma.vm_mm = NULL;
2216         gate_vma.vm_start = FIXADDR_USER_START;
2217         gate_vma.vm_end = FIXADDR_USER_END;
2218         gate_vma.vm_page_prot = PAGE_READONLY;
2219         gate_vma.vm_flags = 0;
2220         return 0;
2221 }
2222 __initcall(gate_vma_init);
2223 #endif
2224
2225 struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
2226 {
2227 #ifdef AT_SYSINFO_EHDR
2228         return &gate_vma;
2229 #else
2230         return NULL;
2231 #endif
2232 }
2233
2234 int in_gate_area_no_task(unsigned long addr)
2235 {
2236 #ifdef AT_SYSINFO_EHDR
2237         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
2238                 return 1;
2239 #endif
2240         return 0;
2241 }
2242
2243 #endif  /* __HAVE_ARCH_GATE_AREA */