Input: atmel_mxt_ts - Improve device configuration
[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/ksm.h>
49 #include <linux/rmap.h>
50 #include <linux/module.h>
51 #include <linux/delayacct.h>
52 #include <linux/init.h>
53 #include <linux/writeback.h>
54 #include <linux/memcontrol.h>
55 #include <linux/mmu_notifier.h>
56 #include <linux/kallsyms.h>
57 #include <linux/swapops.h>
58 #include <linux/elf.h>
59 #include <linux/gfp.h>
60
61 #include <asm/io.h>
62 #include <asm/pgalloc.h>
63 #include <asm/uaccess.h>
64 #include <asm/tlb.h>
65 #include <asm/tlbflush.h>
66 #include <asm/pgtable.h>
67
68 #include "internal.h"
69
70 #ifndef CONFIG_NEED_MULTIPLE_NODES
71 /* use the per-pgdat data instead for discontigmem - mbligh */
72 unsigned long max_mapnr;
73 struct page *mem_map;
74
75 EXPORT_SYMBOL(max_mapnr);
76 EXPORT_SYMBOL(mem_map);
77 #endif
78
79 unsigned long num_physpages;
80 /*
81  * A number of key systems in x86 including ioremap() rely on the assumption
82  * that high_memory defines the upper bound on direct map memory, then end
83  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
84  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
85  * and ZONE_HIGHMEM.
86  */
87 void * high_memory;
88
89 EXPORT_SYMBOL(num_physpages);
90 EXPORT_SYMBOL(high_memory);
91
92 /*
93  * Randomize the address space (stacks, mmaps, brk, etc.).
94  *
95  * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
96  *   as ancient (libc5 based) binaries can segfault. )
97  */
98 int randomize_va_space __read_mostly =
99 #ifdef CONFIG_COMPAT_BRK
100                                         1;
101 #else
102                                         2;
103 #endif
104
105 static int __init disable_randmaps(char *s)
106 {
107         randomize_va_space = 0;
108         return 1;
109 }
110 __setup("norandmaps", disable_randmaps);
111
112 unsigned long zero_pfn __read_mostly;
113 unsigned long highest_memmap_pfn __read_mostly;
114
115 /*
116  * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
117  */
118 static int __init init_zero_pfn(void)
119 {
120         zero_pfn = page_to_pfn(ZERO_PAGE(0));
121         return 0;
122 }
123 core_initcall(init_zero_pfn);
124
125
126 #if defined(SPLIT_RSS_COUNTING)
127
128 static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
129 {
130         int i;
131
132         for (i = 0; i < NR_MM_COUNTERS; i++) {
133                 if (task->rss_stat.count[i]) {
134                         add_mm_counter(mm, i, task->rss_stat.count[i]);
135                         task->rss_stat.count[i] = 0;
136                 }
137         }
138         task->rss_stat.events = 0;
139 }
140
141 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
142 {
143         struct task_struct *task = current;
144
145         if (likely(task->mm == mm))
146                 task->rss_stat.count[member] += val;
147         else
148                 add_mm_counter(mm, member, val);
149 }
150 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
151 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
152
153 /* sync counter once per 64 page faults */
154 #define TASK_RSS_EVENTS_THRESH  (64)
155 static void check_sync_rss_stat(struct task_struct *task)
156 {
157         if (unlikely(task != current))
158                 return;
159         if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
160                 __sync_task_rss_stat(task, task->mm);
161 }
162
163 unsigned long get_mm_counter(struct mm_struct *mm, int member)
164 {
165         long val = 0;
166
167         /*
168          * Don't use task->mm here...for avoiding to use task_get_mm()..
169          * The caller must guarantee task->mm is not invalid.
170          */
171         val = atomic_long_read(&mm->rss_stat.count[member]);
172         /*
173          * counter is updated in asynchronous manner and may go to minus.
174          * But it's never be expected number for users.
175          */
176         if (val < 0)
177                 return 0;
178         return (unsigned long)val;
179 }
180
181 void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
182 {
183         __sync_task_rss_stat(task, mm);
184 }
185 #else /* SPLIT_RSS_COUNTING */
186
187 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
188 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
189
190 static void check_sync_rss_stat(struct task_struct *task)
191 {
192 }
193
194 #endif /* SPLIT_RSS_COUNTING */
195
196 #ifdef HAVE_GENERIC_MMU_GATHER
197
198 static int tlb_next_batch(struct mmu_gather *tlb)
199 {
200         struct mmu_gather_batch *batch;
201
202         batch = tlb->active;
203         if (batch->next) {
204                 tlb->active = batch->next;
205                 return 1;
206         }
207
208         batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
209         if (!batch)
210                 return 0;
211
212         batch->next = NULL;
213         batch->nr   = 0;
214         batch->max  = MAX_GATHER_BATCH;
215
216         tlb->active->next = batch;
217         tlb->active = batch;
218
219         return 1;
220 }
221
222 /* tlb_gather_mmu
223  *      Called to initialize an (on-stack) mmu_gather structure for page-table
224  *      tear-down from @mm. The @fullmm argument is used when @mm is without
225  *      users and we're going to destroy the full address space (exit/execve).
226  */
227 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
228 {
229         tlb->mm = mm;
230
231         tlb->fullmm     = fullmm;
232         tlb->need_flush = 0;
233         tlb->fast_mode  = (num_possible_cpus() == 1);
234         tlb->local.next = NULL;
235         tlb->local.nr   = 0;
236         tlb->local.max  = ARRAY_SIZE(tlb->__pages);
237         tlb->active     = &tlb->local;
238
239 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
240         tlb->batch = NULL;
241 #endif
242 }
243
244 void tlb_flush_mmu(struct mmu_gather *tlb)
245 {
246         struct mmu_gather_batch *batch;
247
248         if (!tlb->need_flush)
249                 return;
250         tlb->need_flush = 0;
251         tlb_flush(tlb);
252 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
253         tlb_table_flush(tlb);
254 #endif
255
256         if (tlb_fast_mode(tlb))
257                 return;
258
259         for (batch = &tlb->local; batch; batch = batch->next) {
260                 free_pages_and_swap_cache(batch->pages, batch->nr);
261                 batch->nr = 0;
262         }
263         tlb->active = &tlb->local;
264 }
265
266 /* tlb_finish_mmu
267  *      Called at the end of the shootdown operation to free up any resources
268  *      that were required.
269  */
270 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
271 {
272         struct mmu_gather_batch *batch, *next;
273
274         tlb_flush_mmu(tlb);
275
276         /* keep the page table cache within bounds */
277         check_pgt_cache();
278
279         for (batch = tlb->local.next; batch; batch = next) {
280                 next = batch->next;
281                 free_pages((unsigned long)batch, 0);
282         }
283         tlb->local.next = NULL;
284 }
285
286 /* __tlb_remove_page
287  *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
288  *      handling the additional races in SMP caused by other CPUs caching valid
289  *      mappings in their TLBs. Returns the number of free page slots left.
290  *      When out of page slots we must call tlb_flush_mmu().
291  */
292 int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
293 {
294         struct mmu_gather_batch *batch;
295
296         tlb->need_flush = 1;
297
298         if (tlb_fast_mode(tlb)) {
299                 free_page_and_swap_cache(page);
300                 return 1; /* avoid calling tlb_flush_mmu() */
301         }
302
303         batch = tlb->active;
304         batch->pages[batch->nr++] = page;
305         if (batch->nr == batch->max) {
306                 if (!tlb_next_batch(tlb))
307                         return 0;
308                 batch = tlb->active;
309         }
310         VM_BUG_ON(batch->nr > batch->max);
311
312         return batch->max - batch->nr;
313 }
314
315 #endif /* HAVE_GENERIC_MMU_GATHER */
316
317 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
318
319 /*
320  * See the comment near struct mmu_table_batch.
321  */
322
323 static void tlb_remove_table_smp_sync(void *arg)
324 {
325         /* Simply deliver the interrupt */
326 }
327
328 static void tlb_remove_table_one(void *table)
329 {
330         /*
331          * This isn't an RCU grace period and hence the page-tables cannot be
332          * assumed to be actually RCU-freed.
333          *
334          * It is however sufficient for software page-table walkers that rely on
335          * IRQ disabling. See the comment near struct mmu_table_batch.
336          */
337         smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
338         __tlb_remove_table(table);
339 }
340
341 static void tlb_remove_table_rcu(struct rcu_head *head)
342 {
343         struct mmu_table_batch *batch;
344         int i;
345
346         batch = container_of(head, struct mmu_table_batch, rcu);
347
348         for (i = 0; i < batch->nr; i++)
349                 __tlb_remove_table(batch->tables[i]);
350
351         free_page((unsigned long)batch);
352 }
353
354 void tlb_table_flush(struct mmu_gather *tlb)
355 {
356         struct mmu_table_batch **batch = &tlb->batch;
357
358         if (*batch) {
359                 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
360                 *batch = NULL;
361         }
362 }
363
364 void tlb_remove_table(struct mmu_gather *tlb, void *table)
365 {
366         struct mmu_table_batch **batch = &tlb->batch;
367
368         tlb->need_flush = 1;
369
370         /*
371          * When there's less then two users of this mm there cannot be a
372          * concurrent page-table walk.
373          */
374         if (atomic_read(&tlb->mm->mm_users) < 2) {
375                 __tlb_remove_table(table);
376                 return;
377         }
378
379         if (*batch == NULL) {
380                 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
381                 if (*batch == NULL) {
382                         tlb_remove_table_one(table);
383                         return;
384                 }
385                 (*batch)->nr = 0;
386         }
387         (*batch)->tables[(*batch)->nr++] = table;
388         if ((*batch)->nr == MAX_TABLE_BATCH)
389                 tlb_table_flush(tlb);
390 }
391
392 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
393
394 /*
395  * If a p?d_bad entry is found while walking page tables, report
396  * the error, before resetting entry to p?d_none.  Usually (but
397  * very seldom) called out from the p?d_none_or_clear_bad macros.
398  */
399
400 void pgd_clear_bad(pgd_t *pgd)
401 {
402         pgd_ERROR(*pgd);
403         pgd_clear(pgd);
404 }
405
406 void pud_clear_bad(pud_t *pud)
407 {
408         pud_ERROR(*pud);
409         pud_clear(pud);
410 }
411
412 void pmd_clear_bad(pmd_t *pmd)
413 {
414         pmd_ERROR(*pmd);
415         pmd_clear(pmd);
416 }
417
418 /*
419  * Note: this doesn't free the actual pages themselves. That
420  * has been handled earlier when unmapping all the memory regions.
421  */
422 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
423                            unsigned long addr)
424 {
425         pgtable_t token = pmd_pgtable(*pmd);
426         pmd_clear(pmd);
427         pte_free_tlb(tlb, token, addr);
428         tlb->mm->nr_ptes--;
429 }
430
431 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
432                                 unsigned long addr, unsigned long end,
433                                 unsigned long floor, unsigned long ceiling)
434 {
435         pmd_t *pmd;
436         unsigned long next;
437         unsigned long start;
438
439         start = addr;
440         pmd = pmd_offset(pud, addr);
441         do {
442                 next = pmd_addr_end(addr, end);
443                 if (pmd_none_or_clear_bad(pmd))
444                         continue;
445                 free_pte_range(tlb, pmd, addr);
446         } while (pmd++, addr = next, addr != end);
447
448         start &= PUD_MASK;
449         if (start < floor)
450                 return;
451         if (ceiling) {
452                 ceiling &= PUD_MASK;
453                 if (!ceiling)
454                         return;
455         }
456         if (end - 1 > ceiling - 1)
457                 return;
458
459         pmd = pmd_offset(pud, start);
460         pud_clear(pud);
461         pmd_free_tlb(tlb, pmd, start);
462 }
463
464 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
465                                 unsigned long addr, unsigned long end,
466                                 unsigned long floor, unsigned long ceiling)
467 {
468         pud_t *pud;
469         unsigned long next;
470         unsigned long start;
471
472         start = addr;
473         pud = pud_offset(pgd, addr);
474         do {
475                 next = pud_addr_end(addr, end);
476                 if (pud_none_or_clear_bad(pud))
477                         continue;
478                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
479         } while (pud++, addr = next, addr != end);
480
481         start &= PGDIR_MASK;
482         if (start < floor)
483                 return;
484         if (ceiling) {
485                 ceiling &= PGDIR_MASK;
486                 if (!ceiling)
487                         return;
488         }
489         if (end - 1 > ceiling - 1)
490                 return;
491
492         pud = pud_offset(pgd, start);
493         pgd_clear(pgd);
494         pud_free_tlb(tlb, pud, start);
495 }
496
497 /*
498  * This function frees user-level page tables of a process.
499  *
500  * Must be called with pagetable lock held.
501  */
502 void free_pgd_range(struct mmu_gather *tlb,
503                         unsigned long addr, unsigned long end,
504                         unsigned long floor, unsigned long ceiling)
505 {
506         pgd_t *pgd;
507         unsigned long next;
508
509         /*
510          * The next few lines have given us lots of grief...
511          *
512          * Why are we testing PMD* at this top level?  Because often
513          * there will be no work to do at all, and we'd prefer not to
514          * go all the way down to the bottom just to discover that.
515          *
516          * Why all these "- 1"s?  Because 0 represents both the bottom
517          * of the address space and the top of it (using -1 for the
518          * top wouldn't help much: the masks would do the wrong thing).
519          * The rule is that addr 0 and floor 0 refer to the bottom of
520          * the address space, but end 0 and ceiling 0 refer to the top
521          * Comparisons need to use "end - 1" and "ceiling - 1" (though
522          * that end 0 case should be mythical).
523          *
524          * Wherever addr is brought up or ceiling brought down, we must
525          * be careful to reject "the opposite 0" before it confuses the
526          * subsequent tests.  But what about where end is brought down
527          * by PMD_SIZE below? no, end can't go down to 0 there.
528          *
529          * Whereas we round start (addr) and ceiling down, by different
530          * masks at different levels, in order to test whether a table
531          * now has no other vmas using it, so can be freed, we don't
532          * bother to round floor or end up - the tests don't need that.
533          */
534
535         addr &= PMD_MASK;
536         if (addr < floor) {
537                 addr += PMD_SIZE;
538                 if (!addr)
539                         return;
540         }
541         if (ceiling) {
542                 ceiling &= PMD_MASK;
543                 if (!ceiling)
544                         return;
545         }
546         if (end - 1 > ceiling - 1)
547                 end -= PMD_SIZE;
548         if (addr > end - 1)
549                 return;
550
551         pgd = pgd_offset(tlb->mm, addr);
552         do {
553                 next = pgd_addr_end(addr, end);
554                 if (pgd_none_or_clear_bad(pgd))
555                         continue;
556                 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
557         } while (pgd++, addr = next, addr != end);
558 }
559
560 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
561                 unsigned long floor, unsigned long ceiling)
562 {
563         while (vma) {
564                 struct vm_area_struct *next = vma->vm_next;
565                 unsigned long addr = vma->vm_start;
566
567                 /*
568                  * Hide vma from rmap and truncate_pagecache before freeing
569                  * pgtables
570                  */
571                 unlink_anon_vmas(vma);
572                 unlink_file_vma(vma);
573
574                 if (is_vm_hugetlb_page(vma)) {
575                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
576                                 floor, next? next->vm_start: ceiling);
577                 } else {
578                         /*
579                          * Optimization: gather nearby vmas into one call down
580                          */
581                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
582                                && !is_vm_hugetlb_page(next)) {
583                                 vma = next;
584                                 next = vma->vm_next;
585                                 unlink_anon_vmas(vma);
586                                 unlink_file_vma(vma);
587                         }
588                         free_pgd_range(tlb, addr, vma->vm_end,
589                                 floor, next? next->vm_start: ceiling);
590                 }
591                 vma = next;
592         }
593 }
594
595 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
596                 pmd_t *pmd, unsigned long address)
597 {
598         pgtable_t new = pte_alloc_one(mm, address);
599         int wait_split_huge_page;
600         if (!new)
601                 return -ENOMEM;
602
603         /*
604          * Ensure all pte setup (eg. pte page lock and page clearing) are
605          * visible before the pte is made visible to other CPUs by being
606          * put into page tables.
607          *
608          * The other side of the story is the pointer chasing in the page
609          * table walking code (when walking the page table without locking;
610          * ie. most of the time). Fortunately, these data accesses consist
611          * of a chain of data-dependent loads, meaning most CPUs (alpha
612          * being the notable exception) will already guarantee loads are
613          * seen in-order. See the alpha page table accessors for the
614          * smp_read_barrier_depends() barriers in page table walking code.
615          */
616         smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
617
618         spin_lock(&mm->page_table_lock);
619         wait_split_huge_page = 0;
620         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
621                 mm->nr_ptes++;
622                 pmd_populate(mm, pmd, new);
623                 new = NULL;
624         } else if (unlikely(pmd_trans_splitting(*pmd)))
625                 wait_split_huge_page = 1;
626         spin_unlock(&mm->page_table_lock);
627         if (new)
628                 pte_free(mm, new);
629         if (wait_split_huge_page)
630                 wait_split_huge_page(vma->anon_vma, pmd);
631         return 0;
632 }
633
634 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
635 {
636         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
637         if (!new)
638                 return -ENOMEM;
639
640         smp_wmb(); /* See comment in __pte_alloc */
641
642         spin_lock(&init_mm.page_table_lock);
643         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
644                 pmd_populate_kernel(&init_mm, pmd, new);
645                 new = NULL;
646         } else
647                 VM_BUG_ON(pmd_trans_splitting(*pmd));
648         spin_unlock(&init_mm.page_table_lock);
649         if (new)
650                 pte_free_kernel(&init_mm, new);
651         return 0;
652 }
653
654 static inline void init_rss_vec(int *rss)
655 {
656         memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
657 }
658
659 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
660 {
661         int i;
662
663         if (current->mm == mm)
664                 sync_mm_rss(current, mm);
665         for (i = 0; i < NR_MM_COUNTERS; i++)
666                 if (rss[i])
667                         add_mm_counter(mm, i, rss[i]);
668 }
669
670 /*
671  * This function is called to print an error when a bad pte
672  * is found. For example, we might have a PFN-mapped pte in
673  * a region that doesn't allow it.
674  *
675  * The calling function must still handle the error.
676  */
677 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
678                           pte_t pte, struct page *page)
679 {
680         pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
681         pud_t *pud = pud_offset(pgd, addr);
682         pmd_t *pmd = pmd_offset(pud, addr);
683         struct address_space *mapping;
684         pgoff_t index;
685         static unsigned long resume;
686         static unsigned long nr_shown;
687         static unsigned long nr_unshown;
688
689         /*
690          * Allow a burst of 60 reports, then keep quiet for that minute;
691          * or allow a steady drip of one report per second.
692          */
693         if (nr_shown == 60) {
694                 if (time_before(jiffies, resume)) {
695                         nr_unshown++;
696                         return;
697                 }
698                 if (nr_unshown) {
699                         printk(KERN_ALERT
700                                 "BUG: Bad page map: %lu messages suppressed\n",
701                                 nr_unshown);
702                         nr_unshown = 0;
703                 }
704                 nr_shown = 0;
705         }
706         if (nr_shown++ == 0)
707                 resume = jiffies + 60 * HZ;
708
709         mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
710         index = linear_page_index(vma, addr);
711
712         printk(KERN_ALERT
713                 "BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
714                 current->comm,
715                 (long long)pte_val(pte), (long long)pmd_val(*pmd));
716         if (page)
717                 dump_page(page);
718         printk(KERN_ALERT
719                 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
720                 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
721         /*
722          * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
723          */
724         if (vma->vm_ops)
725                 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
726                                 (unsigned long)vma->vm_ops->fault);
727         if (vma->vm_file && vma->vm_file->f_op)
728                 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
729                                 (unsigned long)vma->vm_file->f_op->mmap);
730         dump_stack();
731         add_taint(TAINT_BAD_PAGE);
732 }
733
734 static inline int is_cow_mapping(vm_flags_t flags)
735 {
736         return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
737 }
738
739 #ifndef is_zero_pfn
740 static inline int is_zero_pfn(unsigned long pfn)
741 {
742         return pfn == zero_pfn;
743 }
744 #endif
745
746 #ifndef my_zero_pfn
747 static inline unsigned long my_zero_pfn(unsigned long addr)
748 {
749         return zero_pfn;
750 }
751 #endif
752
753 /*
754  * vm_normal_page -- This function gets the "struct page" associated with a pte.
755  *
756  * "Special" mappings do not wish to be associated with a "struct page" (either
757  * it doesn't exist, or it exists but they don't want to touch it). In this
758  * case, NULL is returned here. "Normal" mappings do have a struct page.
759  *
760  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
761  * pte bit, in which case this function is trivial. Secondly, an architecture
762  * may not have a spare pte bit, which requires a more complicated scheme,
763  * described below.
764  *
765  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
766  * special mapping (even if there are underlying and valid "struct pages").
767  * COWed pages of a VM_PFNMAP are always normal.
768  *
769  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
770  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
771  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
772  * mapping will always honor the rule
773  *
774  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
775  *
776  * And for normal mappings this is false.
777  *
778  * This restricts such mappings to be a linear translation from virtual address
779  * to pfn. To get around this restriction, we allow arbitrary mappings so long
780  * as the vma is not a COW mapping; in that case, we know that all ptes are
781  * special (because none can have been COWed).
782  *
783  *
784  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
785  *
786  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
787  * page" backing, however the difference is that _all_ pages with a struct
788  * page (that is, those where pfn_valid is true) are refcounted and considered
789  * normal pages by the VM. The disadvantage is that pages are refcounted
790  * (which can be slower and simply not an option for some PFNMAP users). The
791  * advantage is that we don't have to follow the strict linearity rule of
792  * PFNMAP mappings in order to support COWable mappings.
793  *
794  */
795 #ifdef __HAVE_ARCH_PTE_SPECIAL
796 # define HAVE_PTE_SPECIAL 1
797 #else
798 # define HAVE_PTE_SPECIAL 0
799 #endif
800 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
801                                 pte_t pte)
802 {
803         unsigned long pfn = pte_pfn(pte);
804
805         if (HAVE_PTE_SPECIAL) {
806                 if (likely(!pte_special(pte)))
807                         goto check_pfn;
808                 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
809                         return NULL;
810                 if (!is_zero_pfn(pfn))
811                         print_bad_pte(vma, addr, pte, NULL);
812                 return NULL;
813         }
814
815         /* !HAVE_PTE_SPECIAL case follows: */
816
817         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
818                 if (vma->vm_flags & VM_MIXEDMAP) {
819                         if (!pfn_valid(pfn))
820                                 return NULL;
821                         goto out;
822                 } else {
823                         unsigned long off;
824                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
825                         if (pfn == vma->vm_pgoff + off)
826                                 return NULL;
827                         if (!is_cow_mapping(vma->vm_flags))
828                                 return NULL;
829                 }
830         }
831
832         if (is_zero_pfn(pfn))
833                 return NULL;
834 check_pfn:
835         if (unlikely(pfn > highest_memmap_pfn)) {
836                 print_bad_pte(vma, addr, pte, NULL);
837                 return NULL;
838         }
839
840         /*
841          * NOTE! We still have PageReserved() pages in the page tables.
842          * eg. VDSO mappings can cause them to exist.
843          */
844 out:
845         return pfn_to_page(pfn);
846 }
847
848 /*
849  * copy one vm_area from one task to the other. Assumes the page tables
850  * already present in the new task to be cleared in the whole range
851  * covered by this vma.
852  */
853
854 static inline unsigned long
855 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
856                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
857                 unsigned long addr, int *rss)
858 {
859         unsigned long vm_flags = vma->vm_flags;
860         pte_t pte = *src_pte;
861         struct page *page;
862
863         /* pte contains position in swap or file, so copy. */
864         if (unlikely(!pte_present(pte))) {
865                 if (!pte_file(pte)) {
866                         swp_entry_t entry = pte_to_swp_entry(pte);
867
868                         if (swap_duplicate(entry) < 0)
869                                 return entry.val;
870
871                         /* make sure dst_mm is on swapoff's mmlist. */
872                         if (unlikely(list_empty(&dst_mm->mmlist))) {
873                                 spin_lock(&mmlist_lock);
874                                 if (list_empty(&dst_mm->mmlist))
875                                         list_add(&dst_mm->mmlist,
876                                                  &src_mm->mmlist);
877                                 spin_unlock(&mmlist_lock);
878                         }
879                         if (likely(!non_swap_entry(entry)))
880                                 rss[MM_SWAPENTS]++;
881                         else if (is_write_migration_entry(entry) &&
882                                         is_cow_mapping(vm_flags)) {
883                                 /*
884                                  * COW mappings require pages in both parent
885                                  * and child to be set to read.
886                                  */
887                                 make_migration_entry_read(&entry);
888                                 pte = swp_entry_to_pte(entry);
889                                 set_pte_at(src_mm, addr, src_pte, pte);
890                         }
891                 }
892                 goto out_set_pte;
893         }
894
895         /*
896          * If it's a COW mapping, write protect it both
897          * in the parent and the child
898          */
899         if (is_cow_mapping(vm_flags)) {
900                 ptep_set_wrprotect(src_mm, addr, src_pte);
901                 pte = pte_wrprotect(pte);
902         }
903
904         /*
905          * If it's a shared mapping, mark it clean in
906          * the child
907          */
908         if (vm_flags & VM_SHARED)
909                 pte = pte_mkclean(pte);
910         pte = pte_mkold(pte);
911
912         page = vm_normal_page(vma, addr, pte);
913         if (page) {
914                 get_page(page);
915                 page_dup_rmap(page);
916                 if (PageAnon(page))
917                         rss[MM_ANONPAGES]++;
918                 else
919                         rss[MM_FILEPAGES]++;
920         }
921
922 out_set_pte:
923         set_pte_at(dst_mm, addr, dst_pte, pte);
924         return 0;
925 }
926
927 int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
928                    pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
929                    unsigned long addr, unsigned long end)
930 {
931         pte_t *orig_src_pte, *orig_dst_pte;
932         pte_t *src_pte, *dst_pte;
933         spinlock_t *src_ptl, *dst_ptl;
934         int progress = 0;
935         int rss[NR_MM_COUNTERS];
936         swp_entry_t entry = (swp_entry_t){0};
937
938 again:
939         init_rss_vec(rss);
940
941         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
942         if (!dst_pte)
943                 return -ENOMEM;
944         src_pte = pte_offset_map(src_pmd, addr);
945         src_ptl = pte_lockptr(src_mm, src_pmd);
946         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
947         orig_src_pte = src_pte;
948         orig_dst_pte = dst_pte;
949         arch_enter_lazy_mmu_mode();
950
951         do {
952                 /*
953                  * We are holding two locks at this point - either of them
954                  * could generate latencies in another task on another CPU.
955                  */
956                 if (progress >= 32) {
957                         progress = 0;
958                         if (need_resched() ||
959                             spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
960                                 break;
961                 }
962                 if (pte_none(*src_pte)) {
963                         progress++;
964                         continue;
965                 }
966                 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
967                                                         vma, addr, rss);
968                 if (entry.val)
969                         break;
970                 progress += 8;
971         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
972
973         arch_leave_lazy_mmu_mode();
974         spin_unlock(src_ptl);
975         pte_unmap(orig_src_pte);
976         add_mm_rss_vec(dst_mm, rss);
977         pte_unmap_unlock(orig_dst_pte, dst_ptl);
978         cond_resched();
979
980         if (entry.val) {
981                 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
982                         return -ENOMEM;
983                 progress = 0;
984         }
985         if (addr != end)
986                 goto again;
987         return 0;
988 }
989
990 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
991                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
992                 unsigned long addr, unsigned long end)
993 {
994         pmd_t *src_pmd, *dst_pmd;
995         unsigned long next;
996
997         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
998         if (!dst_pmd)
999                 return -ENOMEM;
1000         src_pmd = pmd_offset(src_pud, addr);
1001         do {
1002                 next = pmd_addr_end(addr, end);
1003                 if (pmd_trans_huge(*src_pmd)) {
1004                         int err;
1005                         VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
1006                         err = copy_huge_pmd(dst_mm, src_mm,
1007                                             dst_pmd, src_pmd, addr, vma);
1008                         if (err == -ENOMEM)
1009                                 return -ENOMEM;
1010                         if (!err)
1011                                 continue;
1012                         /* fall through */
1013                 }
1014                 if (pmd_none_or_clear_bad(src_pmd))
1015                         continue;
1016                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1017                                                 vma, addr, next))
1018                         return -ENOMEM;
1019         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1020         return 0;
1021 }
1022
1023 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1024                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1025                 unsigned long addr, unsigned long end)
1026 {
1027         pud_t *src_pud, *dst_pud;
1028         unsigned long next;
1029
1030         dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
1031         if (!dst_pud)
1032                 return -ENOMEM;
1033         src_pud = pud_offset(src_pgd, addr);
1034         do {
1035                 next = pud_addr_end(addr, end);
1036                 if (pud_none_or_clear_bad(src_pud))
1037                         continue;
1038                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1039                                                 vma, addr, next))
1040                         return -ENOMEM;
1041         } while (dst_pud++, src_pud++, addr = next, addr != end);
1042         return 0;
1043 }
1044
1045 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1046                 struct vm_area_struct *vma)
1047 {
1048         pgd_t *src_pgd, *dst_pgd;
1049         unsigned long next;
1050         unsigned long addr = vma->vm_start;
1051         unsigned long end = vma->vm_end;
1052         int ret;
1053
1054         /*
1055          * Don't copy ptes where a page fault will fill them correctly.
1056          * Fork becomes much lighter when there are big shared or private
1057          * readonly mappings. The tradeoff is that copy_page_range is more
1058          * efficient than faulting.
1059          */
1060         if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
1061                 if (!vma->anon_vma)
1062                         return 0;
1063         }
1064
1065         if (is_vm_hugetlb_page(vma))
1066                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1067
1068         if (unlikely(is_pfn_mapping(vma))) {
1069                 /*
1070                  * We do not free on error cases below as remove_vma
1071                  * gets called on error from higher level routine
1072                  */
1073                 ret = track_pfn_vma_copy(vma);
1074                 if (ret)
1075                         return ret;
1076         }
1077
1078         /*
1079          * We need to invalidate the secondary MMU mappings only when
1080          * there could be a permission downgrade on the ptes of the
1081          * parent mm. And a permission downgrade will only happen if
1082          * is_cow_mapping() returns true.
1083          */
1084         if (is_cow_mapping(vma->vm_flags))
1085                 mmu_notifier_invalidate_range_start(src_mm, addr, end);
1086
1087         ret = 0;
1088         dst_pgd = pgd_offset(dst_mm, addr);
1089         src_pgd = pgd_offset(src_mm, addr);
1090         do {
1091                 next = pgd_addr_end(addr, end);
1092                 if (pgd_none_or_clear_bad(src_pgd))
1093                         continue;
1094                 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1095                                             vma, addr, next))) {
1096                         ret = -ENOMEM;
1097                         break;
1098                 }
1099         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1100
1101         if (is_cow_mapping(vma->vm_flags))
1102                 mmu_notifier_invalidate_range_end(src_mm,
1103                                                   vma->vm_start, end);
1104         return ret;
1105 }
1106
1107 static unsigned long zap_pte_range(struct mmu_gather *tlb,
1108                                 struct vm_area_struct *vma, pmd_t *pmd,
1109                                 unsigned long addr, unsigned long end,
1110                                 struct zap_details *details)
1111 {
1112         struct mm_struct *mm = tlb->mm;
1113         int force_flush = 0;
1114         int rss[NR_MM_COUNTERS];
1115         spinlock_t *ptl;
1116         pte_t *start_pte;
1117         pte_t *pte;
1118
1119 again:
1120         init_rss_vec(rss);
1121         start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1122         pte = start_pte;
1123         arch_enter_lazy_mmu_mode();
1124         do {
1125                 pte_t ptent = *pte;
1126                 if (pte_none(ptent)) {
1127                         continue;
1128                 }
1129
1130                 if (pte_present(ptent)) {
1131                         struct page *page;
1132
1133                         page = vm_normal_page(vma, addr, ptent);
1134                         if (unlikely(details) && page) {
1135                                 /*
1136                                  * unmap_shared_mapping_pages() wants to
1137                                  * invalidate cache without truncating:
1138                                  * unmap shared but keep private pages.
1139                                  */
1140                                 if (details->check_mapping &&
1141                                     details->check_mapping != page->mapping)
1142                                         continue;
1143                                 /*
1144                                  * Each page->index must be checked when
1145                                  * invalidating or truncating nonlinear.
1146                                  */
1147                                 if (details->nonlinear_vma &&
1148                                     (page->index < details->first_index ||
1149                                      page->index > details->last_index))
1150                                         continue;
1151                         }
1152                         ptent = ptep_get_and_clear_full(mm, addr, pte,
1153                                                         tlb->fullmm);
1154                         tlb_remove_tlb_entry(tlb, pte, addr);
1155                         if (unlikely(!page))
1156                                 continue;
1157                         if (unlikely(details) && details->nonlinear_vma
1158                             && linear_page_index(details->nonlinear_vma,
1159                                                 addr) != page->index)
1160                                 set_pte_at(mm, addr, pte,
1161                                            pgoff_to_pte(page->index));
1162                         if (PageAnon(page))
1163                                 rss[MM_ANONPAGES]--;
1164                         else {
1165                                 if (pte_dirty(ptent))
1166                                         set_page_dirty(page);
1167                                 if (pte_young(ptent) &&
1168                                     likely(!VM_SequentialReadHint(vma)))
1169                                         mark_page_accessed(page);
1170                                 rss[MM_FILEPAGES]--;
1171                         }
1172                         page_remove_rmap(page);
1173                         if (unlikely(page_mapcount(page) < 0))
1174                                 print_bad_pte(vma, addr, ptent, page);
1175                         force_flush = !__tlb_remove_page(tlb, page);
1176                         if (force_flush)
1177                                 break;
1178                         continue;
1179                 }
1180                 /*
1181                  * If details->check_mapping, we leave swap entries;
1182                  * if details->nonlinear_vma, we leave file entries.
1183                  */
1184                 if (unlikely(details))
1185                         continue;
1186                 if (pte_file(ptent)) {
1187                         if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1188                                 print_bad_pte(vma, addr, ptent, NULL);
1189                 } else {
1190                         swp_entry_t entry = pte_to_swp_entry(ptent);
1191
1192                         if (!non_swap_entry(entry))
1193                                 rss[MM_SWAPENTS]--;
1194                         if (unlikely(!free_swap_and_cache(entry)))
1195                                 print_bad_pte(vma, addr, ptent, NULL);
1196                 }
1197                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1198         } while (pte++, addr += PAGE_SIZE, addr != end);
1199
1200         add_mm_rss_vec(mm, rss);
1201         arch_leave_lazy_mmu_mode();
1202         pte_unmap_unlock(start_pte, ptl);
1203
1204         /*
1205          * mmu_gather ran out of room to batch pages, we break out of
1206          * the PTE lock to avoid doing the potential expensive TLB invalidate
1207          * and page-free while holding it.
1208          */
1209         if (force_flush) {
1210                 force_flush = 0;
1211                 tlb_flush_mmu(tlb);
1212                 if (addr != end)
1213                         goto again;
1214         }
1215
1216         return addr;
1217 }
1218
1219 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1220                                 struct vm_area_struct *vma, pud_t *pud,
1221                                 unsigned long addr, unsigned long end,
1222                                 struct zap_details *details)
1223 {
1224         pmd_t *pmd;
1225         unsigned long next;
1226
1227         pmd = pmd_offset(pud, addr);
1228         do {
1229                 next = pmd_addr_end(addr, end);
1230                 if (pmd_trans_huge(*pmd)) {
1231                         if (next-addr != HPAGE_PMD_SIZE) {
1232                                 VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
1233                                 split_huge_page_pmd(vma->vm_mm, pmd);
1234                         } else if (zap_huge_pmd(tlb, vma, pmd))
1235                                 continue;
1236                         /* fall through */
1237                 }
1238                 if (pmd_none_or_clear_bad(pmd))
1239                         continue;
1240                 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1241                 cond_resched();
1242         } while (pmd++, addr = next, addr != end);
1243
1244         return addr;
1245 }
1246
1247 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1248                                 struct vm_area_struct *vma, pgd_t *pgd,
1249                                 unsigned long addr, unsigned long end,
1250                                 struct zap_details *details)
1251 {
1252         pud_t *pud;
1253         unsigned long next;
1254
1255         pud = pud_offset(pgd, addr);
1256         do {
1257                 next = pud_addr_end(addr, end);
1258                 if (pud_none_or_clear_bad(pud))
1259                         continue;
1260                 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1261         } while (pud++, addr = next, addr != end);
1262
1263         return addr;
1264 }
1265
1266 static unsigned long unmap_page_range(struct mmu_gather *tlb,
1267                                 struct vm_area_struct *vma,
1268                                 unsigned long addr, unsigned long end,
1269                                 struct zap_details *details)
1270 {
1271         pgd_t *pgd;
1272         unsigned long next;
1273
1274         if (details && !details->check_mapping && !details->nonlinear_vma)
1275                 details = NULL;
1276
1277         BUG_ON(addr >= end);
1278         mem_cgroup_uncharge_start();
1279         tlb_start_vma(tlb, vma);
1280         pgd = pgd_offset(vma->vm_mm, addr);
1281         do {
1282                 next = pgd_addr_end(addr, end);
1283                 if (pgd_none_or_clear_bad(pgd))
1284                         continue;
1285                 next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1286         } while (pgd++, addr = next, addr != end);
1287         tlb_end_vma(tlb, vma);
1288         mem_cgroup_uncharge_end();
1289
1290         return addr;
1291 }
1292
1293 #ifdef CONFIG_PREEMPT
1294 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
1295 #else
1296 /* No preempt: go for improved straight-line efficiency */
1297 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
1298 #endif
1299
1300 /**
1301  * unmap_vmas - unmap a range of memory covered by a list of vma's
1302  * @tlb: address of the caller's struct mmu_gather
1303  * @vma: the starting vma
1304  * @start_addr: virtual address at which to start unmapping
1305  * @end_addr: virtual address at which to end unmapping
1306  * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
1307  * @details: details of nonlinear truncation or shared cache invalidation
1308  *
1309  * Returns the end address of the unmapping (restart addr if interrupted).
1310  *
1311  * Unmap all pages in the vma list.
1312  *
1313  * We aim to not hold locks for too long (for scheduling latency reasons).
1314  * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
1315  * return the ending mmu_gather to the caller.
1316  *
1317  * Only addresses between `start' and `end' will be unmapped.
1318  *
1319  * The VMA list must be sorted in ascending virtual address order.
1320  *
1321  * unmap_vmas() assumes that the caller will flush the whole unmapped address
1322  * range after unmap_vmas() returns.  So the only responsibility here is to
1323  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1324  * drops the lock and schedules.
1325  */
1326 unsigned long unmap_vmas(struct mmu_gather *tlb,
1327                 struct vm_area_struct *vma, unsigned long start_addr,
1328                 unsigned long end_addr, unsigned long *nr_accounted,
1329                 struct zap_details *details)
1330 {
1331         unsigned long start = start_addr;
1332         struct mm_struct *mm = vma->vm_mm;
1333
1334         mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1335         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
1336                 unsigned long end;
1337
1338                 start = max(vma->vm_start, start_addr);
1339                 if (start >= vma->vm_end)
1340                         continue;
1341                 end = min(vma->vm_end, end_addr);
1342                 if (end <= vma->vm_start)
1343                         continue;
1344
1345                 if (vma->vm_flags & VM_ACCOUNT)
1346                         *nr_accounted += (end - start) >> PAGE_SHIFT;
1347
1348                 if (unlikely(is_pfn_mapping(vma)))
1349                         untrack_pfn_vma(vma, 0, 0);
1350
1351                 while (start != end) {
1352                         if (unlikely(is_vm_hugetlb_page(vma))) {
1353                                 /*
1354                                  * It is undesirable to test vma->vm_file as it
1355                                  * should be non-null for valid hugetlb area.
1356                                  * However, vm_file will be NULL in the error
1357                                  * cleanup path of do_mmap_pgoff. When
1358                                  * hugetlbfs ->mmap method fails,
1359                                  * do_mmap_pgoff() nullifies vma->vm_file
1360                                  * before calling this function to clean up.
1361                                  * Since no pte has actually been setup, it is
1362                                  * safe to do nothing in this case.
1363                                  */
1364                                 if (vma->vm_file)
1365                                         unmap_hugepage_range(vma, start, end, NULL);
1366
1367                                 start = end;
1368                         } else
1369                                 start = unmap_page_range(tlb, vma, start, end, details);
1370                 }
1371         }
1372
1373         mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1374         return start;   /* which is now the end (or restart) address */
1375 }
1376
1377 /**
1378  * zap_page_range - remove user pages in a given range
1379  * @vma: vm_area_struct holding the applicable pages
1380  * @address: starting address of pages to zap
1381  * @size: number of bytes to zap
1382  * @details: details of nonlinear truncation or shared cache invalidation
1383  */
1384 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
1385                 unsigned long size, struct zap_details *details)
1386 {
1387         struct mm_struct *mm = vma->vm_mm;
1388         struct mmu_gather tlb;
1389         unsigned long end = address + size;
1390         unsigned long nr_accounted = 0;
1391
1392         lru_add_drain();
1393         tlb_gather_mmu(&tlb, mm, 0);
1394         update_hiwater_rss(mm);
1395         end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1396         tlb_finish_mmu(&tlb, address, end);
1397         return end;
1398 }
1399
1400 /**
1401  * zap_vma_ptes - remove ptes mapping the vma
1402  * @vma: vm_area_struct holding ptes to be zapped
1403  * @address: starting address of pages to zap
1404  * @size: number of bytes to zap
1405  *
1406  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1407  *
1408  * The entire address range must be fully contained within the vma.
1409  *
1410  * Returns 0 if successful.
1411  */
1412 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1413                 unsigned long size)
1414 {
1415         if (address < vma->vm_start || address + size > vma->vm_end ||
1416                         !(vma->vm_flags & VM_PFNMAP))
1417                 return -1;
1418         zap_page_range(vma, address, size, NULL);
1419         return 0;
1420 }
1421 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1422
1423 /**
1424  * follow_page - look up a page descriptor from a user-virtual address
1425  * @vma: vm_area_struct mapping @address
1426  * @address: virtual address to look up
1427  * @flags: flags modifying lookup behaviour
1428  *
1429  * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1430  *
1431  * Returns the mapped (struct page *), %NULL if no mapping exists, or
1432  * an error pointer if there is a mapping to something not represented
1433  * by a page descriptor (see also vm_normal_page()).
1434  */
1435 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1436                         unsigned int flags)
1437 {
1438         pgd_t *pgd;
1439         pud_t *pud;
1440         pmd_t *pmd;
1441         pte_t *ptep, pte;
1442         spinlock_t *ptl;
1443         struct page *page;
1444         struct mm_struct *mm = vma->vm_mm;
1445
1446         page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1447         if (!IS_ERR(page)) {
1448                 BUG_ON(flags & FOLL_GET);
1449                 goto out;
1450         }
1451
1452         page = NULL;
1453         pgd = pgd_offset(mm, address);
1454         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1455                 goto no_page_table;
1456
1457         pud = pud_offset(pgd, address);
1458         if (pud_none(*pud))
1459                 goto no_page_table;
1460         if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1461                 BUG_ON(flags & FOLL_GET);
1462                 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1463                 goto out;
1464         }
1465         if (unlikely(pud_bad(*pud)))
1466                 goto no_page_table;
1467
1468         pmd = pmd_offset(pud, address);
1469         if (pmd_none(*pmd))
1470                 goto no_page_table;
1471         if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1472                 BUG_ON(flags & FOLL_GET);
1473                 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1474                 goto out;
1475         }
1476         if (pmd_trans_huge(*pmd)) {
1477                 if (flags & FOLL_SPLIT) {
1478                         split_huge_page_pmd(mm, pmd);
1479                         goto split_fallthrough;
1480                 }
1481                 spin_lock(&mm->page_table_lock);
1482                 if (likely(pmd_trans_huge(*pmd))) {
1483                         if (unlikely(pmd_trans_splitting(*pmd))) {
1484                                 spin_unlock(&mm->page_table_lock);
1485                                 wait_split_huge_page(vma->anon_vma, pmd);
1486                         } else {
1487                                 page = follow_trans_huge_pmd(mm, address,
1488                                                              pmd, flags);
1489                                 spin_unlock(&mm->page_table_lock);
1490                                 goto out;
1491                         }
1492                 } else
1493                         spin_unlock(&mm->page_table_lock);
1494                 /* fall through */
1495         }
1496 split_fallthrough:
1497         if (unlikely(pmd_bad(*pmd)))
1498                 goto no_page_table;
1499
1500         ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1501
1502         pte = *ptep;
1503         if (!pte_present(pte))
1504                 goto no_page;
1505         if ((flags & FOLL_WRITE) && !pte_write(pte))
1506                 goto unlock;
1507
1508         page = vm_normal_page(vma, address, pte);
1509         if (unlikely(!page)) {
1510                 if ((flags & FOLL_DUMP) ||
1511                     !is_zero_pfn(pte_pfn(pte)))
1512                         goto bad_page;
1513                 page = pte_page(pte);
1514         }
1515
1516         if (flags & FOLL_GET)
1517                 get_page(page);
1518         if (flags & FOLL_TOUCH) {
1519                 if ((flags & FOLL_WRITE) &&
1520                     !pte_dirty(pte) && !PageDirty(page))
1521                         set_page_dirty(page);
1522                 /*
1523                  * pte_mkyoung() would be more correct here, but atomic care
1524                  * is needed to avoid losing the dirty bit: it is easier to use
1525                  * mark_page_accessed().
1526                  */
1527                 mark_page_accessed(page);
1528         }
1529         if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1530                 /*
1531                  * The preliminary mapping check is mainly to avoid the
1532                  * pointless overhead of lock_page on the ZERO_PAGE
1533                  * which might bounce very badly if there is contention.
1534                  *
1535                  * If the page is already locked, we don't need to
1536                  * handle it now - vmscan will handle it later if and
1537                  * when it attempts to reclaim the page.
1538                  */
1539                 if (page->mapping && trylock_page(page)) {
1540                         lru_add_drain();  /* push cached pages to LRU */
1541                         /*
1542                          * Because we lock page here and migration is
1543                          * blocked by the pte's page reference, we need
1544                          * only check for file-cache page truncation.
1545                          */
1546                         if (page->mapping)
1547                                 mlock_vma_page(page);
1548                         unlock_page(page);
1549                 }
1550         }
1551 unlock:
1552         pte_unmap_unlock(ptep, ptl);
1553 out:
1554         return page;
1555
1556 bad_page:
1557         pte_unmap_unlock(ptep, ptl);
1558         return ERR_PTR(-EFAULT);
1559
1560 no_page:
1561         pte_unmap_unlock(ptep, ptl);
1562         if (!pte_none(pte))
1563                 return page;
1564
1565 no_page_table:
1566         /*
1567          * When core dumping an enormous anonymous area that nobody
1568          * has touched so far, we don't want to allocate unnecessary pages or
1569          * page tables.  Return error instead of NULL to skip handle_mm_fault,
1570          * then get_dump_page() will return NULL to leave a hole in the dump.
1571          * But we can only make this optimization where a hole would surely
1572          * be zero-filled if handle_mm_fault() actually did handle it.
1573          */
1574         if ((flags & FOLL_DUMP) &&
1575             (!vma->vm_ops || !vma->vm_ops->fault))
1576                 return ERR_PTR(-EFAULT);
1577         return page;
1578 }
1579
1580 static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1581 {
1582         return stack_guard_page_start(vma, addr) ||
1583                stack_guard_page_end(vma, addr+PAGE_SIZE);
1584 }
1585
1586 /**
1587  * __get_user_pages() - pin user pages in memory
1588  * @tsk:        task_struct of target task
1589  * @mm:         mm_struct of target mm
1590  * @start:      starting user address
1591  * @nr_pages:   number of pages from start to pin
1592  * @gup_flags:  flags modifying pin behaviour
1593  * @pages:      array that receives pointers to the pages pinned.
1594  *              Should be at least nr_pages long. Or NULL, if caller
1595  *              only intends to ensure the pages are faulted in.
1596  * @vmas:       array of pointers to vmas corresponding to each page.
1597  *              Or NULL if the caller does not require them.
1598  * @nonblocking: whether waiting for disk IO or mmap_sem contention
1599  *
1600  * Returns number of pages pinned. This may be fewer than the number
1601  * requested. If nr_pages is 0 or negative, returns 0. If no pages
1602  * were pinned, returns -errno. Each page returned must be released
1603  * with a put_page() call when it is finished with. vmas will only
1604  * remain valid while mmap_sem is held.
1605  *
1606  * Must be called with mmap_sem held for read or write.
1607  *
1608  * __get_user_pages walks a process's page tables and takes a reference to
1609  * each struct page that each user address corresponds to at a given
1610  * instant. That is, it takes the page that would be accessed if a user
1611  * thread accesses the given user virtual address at that instant.
1612  *
1613  * This does not guarantee that the page exists in the user mappings when
1614  * __get_user_pages returns, and there may even be a completely different
1615  * page there in some cases (eg. if mmapped pagecache has been invalidated
1616  * and subsequently re faulted). However it does guarantee that the page
1617  * won't be freed completely. And mostly callers simply care that the page
1618  * contains data that was valid *at some point in time*. Typically, an IO
1619  * or similar operation cannot guarantee anything stronger anyway because
1620  * locks can't be held over the syscall boundary.
1621  *
1622  * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1623  * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1624  * appropriate) must be called after the page is finished with, and
1625  * before put_page is called.
1626  *
1627  * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1628  * or mmap_sem contention, and if waiting is needed to pin all pages,
1629  * *@nonblocking will be set to 0.
1630  *
1631  * In most cases, get_user_pages or get_user_pages_fast should be used
1632  * instead of __get_user_pages. __get_user_pages should be used only if
1633  * you need some special @gup_flags.
1634  */
1635 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1636                      unsigned long start, int nr_pages, unsigned int gup_flags,
1637                      struct page **pages, struct vm_area_struct **vmas,
1638                      int *nonblocking)
1639 {
1640         int i;
1641         unsigned long vm_flags;
1642
1643         if (nr_pages <= 0)
1644                 return 0;
1645
1646         VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1647
1648         /* 
1649          * Require read or write permissions.
1650          * If FOLL_FORCE is set, we only require the "MAY" flags.
1651          */
1652         vm_flags  = (gup_flags & FOLL_WRITE) ?
1653                         (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1654         vm_flags &= (gup_flags & FOLL_FORCE) ?
1655                         (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
1656         i = 0;
1657
1658         do {
1659                 struct vm_area_struct *vma;
1660
1661                 vma = find_extend_vma(mm, start);
1662                 if (!vma && in_gate_area(mm, start)) {
1663                         unsigned long pg = start & PAGE_MASK;
1664                         pgd_t *pgd;
1665                         pud_t *pud;
1666                         pmd_t *pmd;
1667                         pte_t *pte;
1668
1669                         /* user gate pages are read-only */
1670                         if (gup_flags & FOLL_WRITE)
1671                                 return i ? : -EFAULT;
1672                         if (pg > TASK_SIZE)
1673                                 pgd = pgd_offset_k(pg);
1674                         else
1675                                 pgd = pgd_offset_gate(mm, pg);
1676                         BUG_ON(pgd_none(*pgd));
1677                         pud = pud_offset(pgd, pg);
1678                         BUG_ON(pud_none(*pud));
1679                         pmd = pmd_offset(pud, pg);
1680                         if (pmd_none(*pmd))
1681                                 return i ? : -EFAULT;
1682                         VM_BUG_ON(pmd_trans_huge(*pmd));
1683                         pte = pte_offset_map(pmd, pg);
1684                         if (pte_none(*pte)) {
1685                                 pte_unmap(pte);
1686                                 return i ? : -EFAULT;
1687                         }
1688                         vma = get_gate_vma(mm);
1689                         if (pages) {
1690                                 struct page *page;
1691
1692                                 page = vm_normal_page(vma, start, *pte);
1693                                 if (!page) {
1694                                         if (!(gup_flags & FOLL_DUMP) &&
1695                                              is_zero_pfn(pte_pfn(*pte)))
1696                                                 page = pte_page(*pte);
1697                                         else {
1698                                                 pte_unmap(pte);
1699                                                 return i ? : -EFAULT;
1700                                         }
1701                                 }
1702                                 pages[i] = page;
1703                                 get_page(page);
1704                         }
1705                         pte_unmap(pte);
1706                         goto next_page;
1707                 }
1708
1709                 if (!vma ||
1710                     (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
1711                     !(vm_flags & vma->vm_flags))
1712                         return i ? : -EFAULT;
1713
1714                 if (is_vm_hugetlb_page(vma)) {
1715                         i = follow_hugetlb_page(mm, vma, pages, vmas,
1716                                         &start, &nr_pages, i, gup_flags);
1717                         continue;
1718                 }
1719
1720                 do {
1721                         struct page *page;
1722                         unsigned int foll_flags = gup_flags;
1723
1724                         /*
1725                          * If we have a pending SIGKILL, don't keep faulting
1726                          * pages and potentially allocating memory.
1727                          */
1728                         if (unlikely(fatal_signal_pending(current)))
1729                                 return i ? i : -ERESTARTSYS;
1730
1731                         cond_resched();
1732                         while (!(page = follow_page(vma, start, foll_flags))) {
1733                                 int ret;
1734                                 unsigned int fault_flags = 0;
1735
1736                                 /* For mlock, just skip the stack guard page. */
1737                                 if (foll_flags & FOLL_MLOCK) {
1738                                         if (stack_guard_page(vma, start))
1739                                                 goto next_page;
1740                                 }
1741                                 if (foll_flags & FOLL_WRITE)
1742                                         fault_flags |= FAULT_FLAG_WRITE;
1743                                 if (nonblocking)
1744                                         fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1745                                 if (foll_flags & FOLL_NOWAIT)
1746                                         fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1747
1748                                 ret = handle_mm_fault(mm, vma, start,
1749                                                         fault_flags);
1750
1751                                 if (ret & VM_FAULT_ERROR) {
1752                                         if (ret & VM_FAULT_OOM)
1753                                                 return i ? i : -ENOMEM;
1754                                         if (ret & (VM_FAULT_HWPOISON |
1755                                                    VM_FAULT_HWPOISON_LARGE)) {
1756                                                 if (i)
1757                                                         return i;
1758                                                 else if (gup_flags & FOLL_HWPOISON)
1759                                                         return -EHWPOISON;
1760                                                 else
1761                                                         return -EFAULT;
1762                                         }
1763                                         if (ret & VM_FAULT_SIGBUS)
1764                                                 return i ? i : -EFAULT;
1765                                         BUG();
1766                                 }
1767
1768                                 if (tsk) {
1769                                         if (ret & VM_FAULT_MAJOR)
1770                                                 tsk->maj_flt++;
1771                                         else
1772                                                 tsk->min_flt++;
1773                                 }
1774
1775                                 if (ret & VM_FAULT_RETRY) {
1776                                         if (nonblocking)
1777                                                 *nonblocking = 0;
1778                                         return i;
1779                                 }
1780
1781                                 /*
1782                                  * The VM_FAULT_WRITE bit tells us that
1783                                  * do_wp_page has broken COW when necessary,
1784                                  * even if maybe_mkwrite decided not to set
1785                                  * pte_write. We can thus safely do subsequent
1786                                  * page lookups as if they were reads. But only
1787                                  * do so when looping for pte_write is futile:
1788                                  * in some cases userspace may also be wanting
1789                                  * to write to the gotten user page, which a
1790                                  * read fault here might prevent (a readonly
1791                                  * page might get reCOWed by userspace write).
1792                                  */
1793                                 if ((ret & VM_FAULT_WRITE) &&
1794                                     !(vma->vm_flags & VM_WRITE))
1795                                         foll_flags &= ~FOLL_WRITE;
1796
1797                                 cond_resched();
1798                         }
1799                         if (IS_ERR(page))
1800                                 return i ? i : PTR_ERR(page);
1801                         if (pages) {
1802                                 pages[i] = page;
1803
1804                                 flush_anon_page(vma, page, start);
1805                                 flush_dcache_page(page);
1806                         }
1807 next_page:
1808                         if (vmas)
1809                                 vmas[i] = vma;
1810                         i++;
1811                         start += PAGE_SIZE;
1812                         nr_pages--;
1813                 } while (nr_pages && start < vma->vm_end);
1814         } while (nr_pages);
1815         return i;
1816 }
1817 EXPORT_SYMBOL(__get_user_pages);
1818
1819 /**
1820  * get_user_pages() - pin user pages in memory
1821  * @tsk:        the task_struct to use for page fault accounting, or
1822  *              NULL if faults are not to be recorded.
1823  * @mm:         mm_struct of target mm
1824  * @start:      starting user address
1825  * @nr_pages:   number of pages from start to pin
1826  * @write:      whether pages will be written to by the caller
1827  * @force:      whether to force write access even if user mapping is
1828  *              readonly. This will result in the page being COWed even
1829  *              in MAP_SHARED mappings. You do not want this.
1830  * @pages:      array that receives pointers to the pages pinned.
1831  *              Should be at least nr_pages long. Or NULL, if caller
1832  *              only intends to ensure the pages are faulted in.
1833  * @vmas:       array of pointers to vmas corresponding to each page.
1834  *              Or NULL if the caller does not require them.
1835  *
1836  * Returns number of pages pinned. This may be fewer than the number
1837  * requested. If nr_pages is 0 or negative, returns 0. If no pages
1838  * were pinned, returns -errno. Each page returned must be released
1839  * with a put_page() call when it is finished with. vmas will only
1840  * remain valid while mmap_sem is held.
1841  *
1842  * Must be called with mmap_sem held for read or write.
1843  *
1844  * get_user_pages walks a process's page tables and takes a reference to
1845  * each struct page that each user address corresponds to at a given
1846  * instant. That is, it takes the page that would be accessed if a user
1847  * thread accesses the given user virtual address at that instant.
1848  *
1849  * This does not guarantee that the page exists in the user mappings when
1850  * get_user_pages returns, and there may even be a completely different
1851  * page there in some cases (eg. if mmapped pagecache has been invalidated
1852  * and subsequently re faulted). However it does guarantee that the page
1853  * won't be freed completely. And mostly callers simply care that the page
1854  * contains data that was valid *at some point in time*. Typically, an IO
1855  * or similar operation cannot guarantee anything stronger anyway because
1856  * locks can't be held over the syscall boundary.
1857  *
1858  * If write=0, the page must not be written to. If the page is written to,
1859  * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1860  * after the page is finished with, and before put_page is called.
1861  *
1862  * get_user_pages is typically used for fewer-copy IO operations, to get a
1863  * handle on the memory by some means other than accesses via the user virtual
1864  * addresses. The pages may be submitted for DMA to devices or accessed via
1865  * their kernel linear mapping (via the kmap APIs). Care should be taken to
1866  * use the correct cache flushing APIs.
1867  *
1868  * See also get_user_pages_fast, for performance critical applications.
1869  */
1870 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1871                 unsigned long start, int nr_pages, int write, int force,
1872                 struct page **pages, struct vm_area_struct **vmas)
1873 {
1874         int flags = FOLL_TOUCH;
1875
1876         if (pages)
1877                 flags |= FOLL_GET;
1878         if (write)
1879                 flags |= FOLL_WRITE;
1880         if (force)
1881                 flags |= FOLL_FORCE;
1882
1883         return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
1884                                 NULL);
1885 }
1886 EXPORT_SYMBOL(get_user_pages);
1887
1888 /**
1889  * get_dump_page() - pin user page in memory while writing it to core dump
1890  * @addr: user address
1891  *
1892  * Returns struct page pointer of user page pinned for dump,
1893  * to be freed afterwards by page_cache_release() or put_page().
1894  *
1895  * Returns NULL on any kind of failure - a hole must then be inserted into
1896  * the corefile, to preserve alignment with its headers; and also returns
1897  * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1898  * allowing a hole to be left in the corefile to save diskspace.
1899  *
1900  * Called without mmap_sem, but after all other threads have been killed.
1901  */
1902 #ifdef CONFIG_ELF_CORE
1903 struct page *get_dump_page(unsigned long addr)
1904 {
1905         struct vm_area_struct *vma;
1906         struct page *page;
1907
1908         if (__get_user_pages(current, current->mm, addr, 1,
1909                              FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
1910                              NULL) < 1)
1911                 return NULL;
1912         flush_cache_page(vma, addr, page_to_pfn(page));
1913         return page;
1914 }
1915 #endif /* CONFIG_ELF_CORE */
1916
1917 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1918                         spinlock_t **ptl)
1919 {
1920         pgd_t * pgd = pgd_offset(mm, addr);
1921         pud_t * pud = pud_alloc(mm, pgd, addr);
1922         if (pud) {
1923                 pmd_t * pmd = pmd_alloc(mm, pud, addr);
1924                 if (pmd) {
1925                         VM_BUG_ON(pmd_trans_huge(*pmd));
1926                         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1927                 }
1928         }
1929         return NULL;
1930 }
1931
1932 /*
1933  * This is the old fallback for page remapping.
1934  *
1935  * For historical reasons, it only allows reserved pages. Only
1936  * old drivers should use this, and they needed to mark their
1937  * pages reserved for the old functions anyway.
1938  */
1939 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1940                         struct page *page, pgprot_t prot)
1941 {
1942         struct mm_struct *mm = vma->vm_mm;
1943         int retval;
1944         pte_t *pte;
1945         spinlock_t *ptl;
1946
1947         retval = -EINVAL;
1948         if (PageAnon(page))
1949                 goto out;
1950         retval = -ENOMEM;
1951         flush_dcache_page(page);
1952         pte = get_locked_pte(mm, addr, &ptl);
1953         if (!pte)
1954                 goto out;
1955         retval = -EBUSY;
1956         if (!pte_none(*pte))
1957                 goto out_unlock;
1958
1959         /* Ok, finally just insert the thing.. */
1960         get_page(page);
1961         inc_mm_counter_fast(mm, MM_FILEPAGES);
1962         page_add_file_rmap(page);
1963         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1964
1965         retval = 0;
1966         pte_unmap_unlock(pte, ptl);
1967         return retval;
1968 out_unlock:
1969         pte_unmap_unlock(pte, ptl);
1970 out:
1971         return retval;
1972 }
1973
1974 /**
1975  * vm_insert_page - insert single page into user vma
1976  * @vma: user vma to map to
1977  * @addr: target user address of this page
1978  * @page: source kernel page
1979  *
1980  * This allows drivers to insert individual pages they've allocated
1981  * into a user vma.
1982  *
1983  * The page has to be a nice clean _individual_ kernel allocation.
1984  * If you allocate a compound page, you need to have marked it as
1985  * such (__GFP_COMP), or manually just split the page up yourself
1986  * (see split_page()).
1987  *
1988  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1989  * took an arbitrary page protection parameter. This doesn't allow
1990  * that. Your vma protection will have to be set up correctly, which
1991  * means that if you want a shared writable mapping, you'd better
1992  * ask for a shared writable mapping!
1993  *
1994  * The page does not need to be reserved.
1995  */
1996 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1997                         struct page *page)
1998 {
1999         if (addr < vma->vm_start || addr >= vma->vm_end)
2000                 return -EFAULT;
2001         if (!page_count(page))
2002                 return -EINVAL;
2003         vma->vm_flags |= VM_INSERTPAGE;
2004         return insert_page(vma, addr, page, vma->vm_page_prot);
2005 }
2006 EXPORT_SYMBOL(vm_insert_page);
2007
2008 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2009                         unsigned long pfn, pgprot_t prot)
2010 {
2011         struct mm_struct *mm = vma->vm_mm;
2012         int retval;
2013         pte_t *pte, entry;
2014         spinlock_t *ptl;
2015
2016         retval = -ENOMEM;
2017         pte = get_locked_pte(mm, addr, &ptl);
2018         if (!pte)
2019                 goto out;
2020         retval = -EBUSY;
2021         if (!pte_none(*pte))
2022                 goto out_unlock;
2023
2024         /* Ok, finally just insert the thing.. */
2025         entry = pte_mkspecial(pfn_pte(pfn, prot));
2026         set_pte_at(mm, addr, pte, entry);
2027         update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2028
2029         retval = 0;
2030 out_unlock:
2031         pte_unmap_unlock(pte, ptl);
2032 out:
2033         return retval;
2034 }
2035
2036 /**
2037  * vm_insert_pfn - insert single pfn into user vma
2038  * @vma: user vma to map to
2039  * @addr: target user address of this page
2040  * @pfn: source kernel pfn
2041  *
2042  * Similar to vm_inert_page, this allows drivers to insert individual pages
2043  * they've allocated into a user vma. Same comments apply.
2044  *
2045  * This function should only be called from a vm_ops->fault handler, and
2046  * in that case the handler should return NULL.
2047  *
2048  * vma cannot be a COW mapping.
2049  *
2050  * As this is called only for pages that do not currently exist, we
2051  * do not need to flush old virtual caches or the TLB.
2052  */
2053 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2054                         unsigned long pfn)
2055 {
2056         int ret;
2057         pgprot_t pgprot = vma->vm_page_prot;
2058         /*
2059          * Technically, architectures with pte_special can avoid all these
2060          * restrictions (same for remap_pfn_range).  However we would like
2061          * consistency in testing and feature parity among all, so we should
2062          * try to keep these invariants in place for everybody.
2063          */
2064         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2065         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2066                                                 (VM_PFNMAP|VM_MIXEDMAP));
2067         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2068         BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2069
2070         if (addr < vma->vm_start || addr >= vma->vm_end)
2071                 return -EFAULT;
2072         if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
2073                 return -EINVAL;
2074
2075         ret = insert_pfn(vma, addr, pfn, pgprot);
2076
2077         if (ret)
2078                 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
2079
2080         return ret;
2081 }
2082 EXPORT_SYMBOL(vm_insert_pfn);
2083
2084 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2085                         unsigned long pfn)
2086 {
2087         BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2088
2089         if (addr < vma->vm_start || addr >= vma->vm_end)
2090                 return -EFAULT;
2091
2092         /*
2093          * If we don't have pte special, then we have to use the pfn_valid()
2094          * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2095          * refcount the page if pfn_valid is true (hence insert_page rather
2096          * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
2097          * without pte special, it would there be refcounted as a normal page.
2098          */
2099         if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2100                 struct page *page;
2101
2102                 page = pfn_to_page(pfn);
2103                 return insert_page(vma, addr, page, vma->vm_page_prot);
2104         }
2105         return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2106 }
2107 EXPORT_SYMBOL(vm_insert_mixed);
2108
2109 /*
2110  * maps a range of physical memory into the requested pages. the old
2111  * mappings are removed. any references to nonexistent pages results
2112  * in null mappings (currently treated as "copy-on-access")
2113  */
2114 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2115                         unsigned long addr, unsigned long end,
2116                         unsigned long pfn, pgprot_t prot)
2117 {
2118         pte_t *pte;
2119         spinlock_t *ptl;
2120
2121         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2122         if (!pte)
2123                 return -ENOMEM;
2124         arch_enter_lazy_mmu_mode();
2125         do {
2126                 BUG_ON(!pte_none(*pte));
2127                 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2128                 pfn++;
2129         } while (pte++, addr += PAGE_SIZE, addr != end);
2130         arch_leave_lazy_mmu_mode();
2131         pte_unmap_unlock(pte - 1, ptl);
2132         return 0;
2133 }
2134
2135 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2136                         unsigned long addr, unsigned long end,
2137                         unsigned long pfn, pgprot_t prot)
2138 {
2139         pmd_t *pmd;
2140         unsigned long next;
2141
2142         pfn -= addr >> PAGE_SHIFT;
2143         pmd = pmd_alloc(mm, pud, addr);
2144         if (!pmd)
2145                 return -ENOMEM;
2146         VM_BUG_ON(pmd_trans_huge(*pmd));
2147         do {
2148                 next = pmd_addr_end(addr, end);
2149                 if (remap_pte_range(mm, pmd, addr, next,
2150                                 pfn + (addr >> PAGE_SHIFT), prot))
2151                         return -ENOMEM;
2152         } while (pmd++, addr = next, addr != end);
2153         return 0;
2154 }
2155
2156 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
2157                         unsigned long addr, unsigned long end,
2158                         unsigned long pfn, pgprot_t prot)
2159 {
2160         pud_t *pud;
2161         unsigned long next;
2162
2163         pfn -= addr >> PAGE_SHIFT;
2164         pud = pud_alloc(mm, pgd, addr);
2165         if (!pud)
2166                 return -ENOMEM;
2167         do {
2168                 next = pud_addr_end(addr, end);
2169                 if (remap_pmd_range(mm, pud, addr, next,
2170                                 pfn + (addr >> PAGE_SHIFT), prot))
2171                         return -ENOMEM;
2172         } while (pud++, addr = next, addr != end);
2173         return 0;
2174 }
2175
2176 /**
2177  * remap_pfn_range - remap kernel memory to userspace
2178  * @vma: user vma to map to
2179  * @addr: target user address to start at
2180  * @pfn: physical address of kernel memory
2181  * @size: size of map area
2182  * @prot: page protection flags for this mapping
2183  *
2184  *  Note: this is only safe if the mm semaphore is held when called.
2185  */
2186 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2187                     unsigned long pfn, unsigned long size, pgprot_t prot)
2188 {
2189         pgd_t *pgd;
2190         unsigned long next;
2191         unsigned long end = addr + PAGE_ALIGN(size);
2192         struct mm_struct *mm = vma->vm_mm;
2193         int err;
2194
2195         /*
2196          * Physically remapped pages are special. Tell the
2197          * rest of the world about it:
2198          *   VM_IO tells people not to look at these pages
2199          *      (accesses can have side effects).
2200          *   VM_RESERVED is specified all over the place, because
2201          *      in 2.4 it kept swapout's vma scan off this vma; but
2202          *      in 2.6 the LRU scan won't even find its pages, so this
2203          *      flag means no more than count its pages in reserved_vm,
2204          *      and omit it from core dump, even when VM_IO turned off.
2205          *   VM_PFNMAP tells the core MM that the base pages are just
2206          *      raw PFN mappings, and do not have a "struct page" associated
2207          *      with them.
2208          *
2209          * There's a horrible special case to handle copy-on-write
2210          * behaviour that some programs depend on. We mark the "original"
2211          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2212          */
2213         if (addr == vma->vm_start && end == vma->vm_end) {
2214                 vma->vm_pgoff = pfn;
2215                 vma->vm_flags |= VM_PFN_AT_MMAP;
2216         } else if (is_cow_mapping(vma->vm_flags))
2217                 return -EINVAL;
2218
2219         vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
2220
2221         err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
2222         if (err) {
2223                 /*
2224                  * To indicate that track_pfn related cleanup is not
2225                  * needed from higher level routine calling unmap_vmas
2226                  */
2227                 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
2228                 vma->vm_flags &= ~VM_PFN_AT_MMAP;
2229                 return -EINVAL;
2230         }
2231
2232         BUG_ON(addr >= end);
2233         pfn -= addr >> PAGE_SHIFT;
2234         pgd = pgd_offset(mm, addr);
2235         flush_cache_range(vma, addr, end);
2236         do {
2237                 next = pgd_addr_end(addr, end);
2238                 err = remap_pud_range(mm, pgd, addr, next,
2239                                 pfn + (addr >> PAGE_SHIFT), prot);
2240                 if (err)
2241                         break;
2242         } while (pgd++, addr = next, addr != end);
2243
2244         if (err)
2245                 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
2246
2247         return err;
2248 }
2249 EXPORT_SYMBOL(remap_pfn_range);
2250
2251 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2252                                      unsigned long addr, unsigned long end,
2253                                      pte_fn_t fn, void *data)
2254 {
2255         pte_t *pte;
2256         int err;
2257         pgtable_t token;
2258         spinlock_t *uninitialized_var(ptl);
2259
2260         pte = (mm == &init_mm) ?
2261                 pte_alloc_kernel(pmd, addr) :
2262                 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2263         if (!pte)
2264                 return -ENOMEM;
2265
2266         BUG_ON(pmd_huge(*pmd));
2267
2268         arch_enter_lazy_mmu_mode();
2269
2270         token = pmd_pgtable(*pmd);
2271
2272         do {
2273                 err = fn(pte++, token, addr, data);
2274                 if (err)
2275                         break;
2276         } while (addr += PAGE_SIZE, addr != end);
2277
2278         arch_leave_lazy_mmu_mode();
2279
2280         if (mm != &init_mm)
2281                 pte_unmap_unlock(pte-1, ptl);
2282         return err;
2283 }
2284
2285 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2286                                      unsigned long addr, unsigned long end,
2287                                      pte_fn_t fn, void *data)
2288 {
2289         pmd_t *pmd;
2290         unsigned long next;
2291         int err;
2292
2293         BUG_ON(pud_huge(*pud));
2294
2295         pmd = pmd_alloc(mm, pud, addr);
2296         if (!pmd)
2297                 return -ENOMEM;
2298         do {
2299                 next = pmd_addr_end(addr, end);
2300                 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2301                 if (err)
2302                         break;
2303         } while (pmd++, addr = next, addr != end);
2304         return err;
2305 }
2306
2307 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2308                                      unsigned long addr, unsigned long end,
2309                                      pte_fn_t fn, void *data)
2310 {
2311         pud_t *pud;
2312         unsigned long next;
2313         int err;
2314
2315         pud = pud_alloc(mm, pgd, addr);
2316         if (!pud)
2317                 return -ENOMEM;
2318         do {
2319                 next = pud_addr_end(addr, end);
2320                 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2321                 if (err)
2322                         break;
2323         } while (pud++, addr = next, addr != end);
2324         return err;
2325 }
2326
2327 /*
2328  * Scan a region of virtual memory, filling in page tables as necessary
2329  * and calling a provided function on each leaf page table.
2330  */
2331 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2332                         unsigned long size, pte_fn_t fn, void *data)
2333 {
2334         pgd_t *pgd;
2335         unsigned long next;
2336         unsigned long end = addr + size;
2337         int err;
2338
2339         BUG_ON(addr >= end);
2340         pgd = pgd_offset(mm, addr);
2341         do {
2342                 next = pgd_addr_end(addr, end);
2343                 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2344                 if (err)
2345                         break;
2346         } while (pgd++, addr = next, addr != end);
2347
2348         return err;
2349 }
2350 EXPORT_SYMBOL_GPL(apply_to_page_range);
2351
2352 /*
2353  * handle_pte_fault chooses page fault handler according to an entry
2354  * which was read non-atomically.  Before making any commitment, on
2355  * those architectures or configurations (e.g. i386 with PAE) which
2356  * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2357  * must check under lock before unmapping the pte and proceeding
2358  * (but do_wp_page is only called after already making such a check;
2359  * and do_anonymous_page can safely check later on).
2360  */
2361 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2362                                 pte_t *page_table, pte_t orig_pte)
2363 {
2364         int same = 1;
2365 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2366         if (sizeof(pte_t) > sizeof(unsigned long)) {
2367                 spinlock_t *ptl = pte_lockptr(mm, pmd);
2368                 spin_lock(ptl);
2369                 same = pte_same(*page_table, orig_pte);
2370                 spin_unlock(ptl);
2371         }
2372 #endif
2373         pte_unmap(page_table);
2374         return same;
2375 }
2376
2377 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2378 {
2379         /*
2380          * If the source page was a PFN mapping, we don't have
2381          * a "struct page" for it. We do a best-effort copy by
2382          * just copying from the original user address. If that
2383          * fails, we just zero-fill it. Live with it.
2384          */
2385         if (unlikely(!src)) {
2386                 void *kaddr = kmap_atomic(dst, KM_USER0);
2387                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2388
2389                 /*
2390                  * This really shouldn't fail, because the page is there
2391                  * in the page tables. But it might just be unreadable,
2392                  * in which case we just give up and fill the result with
2393                  * zeroes.
2394                  */
2395                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2396                         clear_page(kaddr);
2397                 kunmap_atomic(kaddr, KM_USER0);
2398                 flush_dcache_page(dst);
2399         } else
2400                 copy_user_highpage(dst, src, va, vma);
2401 }
2402
2403 /*
2404  * This routine handles present pages, when users try to write
2405  * to a shared page. It is done by copying the page to a new address
2406  * and decrementing the shared-page counter for the old page.
2407  *
2408  * Note that this routine assumes that the protection checks have been
2409  * done by the caller (the low-level page fault routine in most cases).
2410  * Thus we can safely just mark it writable once we've done any necessary
2411  * COW.
2412  *
2413  * We also mark the page dirty at this point even though the page will
2414  * change only once the write actually happens. This avoids a few races,
2415  * and potentially makes it more efficient.
2416  *
2417  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2418  * but allow concurrent faults), with pte both mapped and locked.
2419  * We return with mmap_sem still held, but pte unmapped and unlocked.
2420  */
2421 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2422                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2423                 spinlock_t *ptl, pte_t orig_pte)
2424         __releases(ptl)
2425 {
2426         struct page *old_page, *new_page;
2427         pte_t entry;
2428         int ret = 0;
2429         int page_mkwrite = 0;
2430         struct page *dirty_page = NULL;
2431
2432         old_page = vm_normal_page(vma, address, orig_pte);
2433         if (!old_page) {
2434                 /*
2435                  * VM_MIXEDMAP !pfn_valid() case
2436                  *
2437                  * We should not cow pages in a shared writeable mapping.
2438                  * Just mark the pages writable as we can't do any dirty
2439                  * accounting on raw pfn maps.
2440                  */
2441                 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2442                                      (VM_WRITE|VM_SHARED))
2443                         goto reuse;
2444                 goto gotten;
2445         }
2446
2447         /*
2448          * Take out anonymous pages first, anonymous shared vmas are
2449          * not dirty accountable.
2450          */
2451         if (PageAnon(old_page) && !PageKsm(old_page)) {
2452                 if (!trylock_page(old_page)) {
2453                         page_cache_get(old_page);
2454                         pte_unmap_unlock(page_table, ptl);
2455                         lock_page(old_page);
2456                         page_table = pte_offset_map_lock(mm, pmd, address,
2457                                                          &ptl);
2458                         if (!pte_same(*page_table, orig_pte)) {
2459                                 unlock_page(old_page);
2460                                 goto unlock;
2461                         }
2462                         page_cache_release(old_page);
2463                 }
2464                 if (reuse_swap_page(old_page)) {
2465                         /*
2466                          * The page is all ours.  Move it to our anon_vma so
2467                          * the rmap code will not search our parent or siblings.
2468                          * Protected against the rmap code by the page lock.
2469                          */
2470                         page_move_anon_rmap(old_page, vma, address);
2471                         unlock_page(old_page);
2472                         goto reuse;
2473                 }
2474                 unlock_page(old_page);
2475         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2476                                         (VM_WRITE|VM_SHARED))) {
2477                 /*
2478                  * Only catch write-faults on shared writable pages,
2479                  * read-only shared pages can get COWed by
2480                  * get_user_pages(.write=1, .force=1).
2481                  */
2482                 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2483                         struct vm_fault vmf;
2484                         int tmp;
2485
2486                         vmf.virtual_address = (void __user *)(address &
2487                                                                 PAGE_MASK);
2488                         vmf.pgoff = old_page->index;
2489                         vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2490                         vmf.page = old_page;
2491
2492                         /*
2493                          * Notify the address space that the page is about to
2494                          * become writable so that it can prohibit this or wait
2495                          * for the page to get into an appropriate state.
2496                          *
2497                          * We do this without the lock held, so that it can
2498                          * sleep if it needs to.
2499                          */
2500                         page_cache_get(old_page);
2501                         pte_unmap_unlock(page_table, ptl);
2502
2503                         tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2504                         if (unlikely(tmp &
2505                                         (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2506                                 ret = tmp;
2507                                 goto unwritable_page;
2508                         }
2509                         if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2510                                 lock_page(old_page);
2511                                 if (!old_page->mapping) {
2512                                         ret = 0; /* retry the fault */
2513                                         unlock_page(old_page);
2514                                         goto unwritable_page;
2515                                 }
2516                         } else
2517                                 VM_BUG_ON(!PageLocked(old_page));
2518
2519                         /*
2520                          * Since we dropped the lock we need to revalidate
2521                          * the PTE as someone else may have changed it.  If
2522                          * they did, we just return, as we can count on the
2523                          * MMU to tell us if they didn't also make it writable.
2524                          */
2525                         page_table = pte_offset_map_lock(mm, pmd, address,
2526                                                          &ptl);
2527                         if (!pte_same(*page_table, orig_pte)) {
2528                                 unlock_page(old_page);
2529                                 goto unlock;
2530                         }
2531
2532                         page_mkwrite = 1;
2533                 }
2534                 dirty_page = old_page;
2535                 get_page(dirty_page);
2536
2537 reuse:
2538                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2539                 entry = pte_mkyoung(orig_pte);
2540                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2541                 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2542                         update_mmu_cache(vma, address, page_table);
2543                 pte_unmap_unlock(page_table, ptl);
2544                 ret |= VM_FAULT_WRITE;
2545
2546                 if (!dirty_page)
2547                         return ret;
2548
2549                 /*
2550                  * Yes, Virginia, this is actually required to prevent a race
2551                  * with clear_page_dirty_for_io() from clearing the page dirty
2552                  * bit after it clear all dirty ptes, but before a racing
2553                  * do_wp_page installs a dirty pte.
2554                  *
2555                  * __do_fault is protected similarly.
2556                  */
2557                 if (!page_mkwrite) {
2558                         wait_on_page_locked(dirty_page);
2559                         set_page_dirty_balance(dirty_page, page_mkwrite);
2560                 }
2561                 put_page(dirty_page);
2562                 if (page_mkwrite) {
2563                         struct address_space *mapping = dirty_page->mapping;
2564
2565                         set_page_dirty(dirty_page);
2566                         unlock_page(dirty_page);
2567                         page_cache_release(dirty_page);
2568                         if (mapping)    {
2569                                 /*
2570                                  * Some device drivers do not set page.mapping
2571                                  * but still dirty their pages
2572                                  */
2573                                 balance_dirty_pages_ratelimited(mapping);
2574                         }
2575                 }
2576
2577                 /* file_update_time outside page_lock */
2578                 if (vma->vm_file)
2579                         file_update_time(vma->vm_file);
2580
2581                 return ret;
2582         }
2583
2584         /*
2585          * Ok, we need to copy. Oh, well..
2586          */
2587         page_cache_get(old_page);
2588 gotten:
2589         pte_unmap_unlock(page_table, ptl);
2590
2591         if (unlikely(anon_vma_prepare(vma)))
2592                 goto oom;
2593
2594         if (is_zero_pfn(pte_pfn(orig_pte))) {
2595                 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2596                 if (!new_page)
2597                         goto oom;
2598         } else {
2599                 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2600                 if (!new_page)
2601                         goto oom;
2602                 cow_user_page(new_page, old_page, address, vma);
2603         }
2604         __SetPageUptodate(new_page);
2605
2606         if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2607                 goto oom_free_new;
2608
2609         /*
2610          * Re-check the pte - we dropped the lock
2611          */
2612         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2613         if (likely(pte_same(*page_table, orig_pte))) {
2614                 if (old_page) {
2615                         if (!PageAnon(old_page)) {
2616                                 dec_mm_counter_fast(mm, MM_FILEPAGES);
2617                                 inc_mm_counter_fast(mm, MM_ANONPAGES);
2618                         }
2619                 } else
2620                         inc_mm_counter_fast(mm, MM_ANONPAGES);
2621                 flush_cache_page(vma, address, pte_pfn(orig_pte));
2622                 entry = mk_pte(new_page, vma->vm_page_prot);
2623                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2624                 /*
2625                  * Clear the pte entry and flush it first, before updating the
2626                  * pte with the new entry. This will avoid a race condition
2627                  * seen in the presence of one thread doing SMC and another
2628                  * thread doing COW.
2629                  */
2630                 ptep_clear_flush(vma, address, page_table);
2631                 page_add_new_anon_rmap(new_page, vma, address);
2632                 /*
2633                  * We call the notify macro here because, when using secondary
2634                  * mmu page tables (such as kvm shadow page tables), we want the
2635                  * new page to be mapped directly into the secondary page table.
2636                  */
2637                 set_pte_at_notify(mm, address, page_table, entry);
2638                 update_mmu_cache(vma, address, page_table);
2639                 if (old_page) {
2640                         /*
2641                          * Only after switching the pte to the new page may
2642                          * we remove the mapcount here. Otherwise another
2643                          * process may come and find the rmap count decremented
2644                          * before the pte is switched to the new page, and
2645                          * "reuse" the old page writing into it while our pte
2646                          * here still points into it and can be read by other
2647                          * threads.
2648                          *
2649                          * The critical issue is to order this
2650                          * page_remove_rmap with the ptp_clear_flush above.
2651                          * Those stores are ordered by (if nothing else,)
2652                          * the barrier present in the atomic_add_negative
2653                          * in page_remove_rmap.
2654                          *
2655                          * Then the TLB flush in ptep_clear_flush ensures that
2656                          * no process can access the old page before the
2657                          * decremented mapcount is visible. And the old page
2658                          * cannot be reused until after the decremented
2659                          * mapcount is visible. So transitively, TLBs to
2660                          * old page will be flushed before it can be reused.
2661                          */
2662                         page_remove_rmap(old_page);
2663                 }
2664
2665                 /* Free the old page.. */
2666                 new_page = old_page;
2667                 ret |= VM_FAULT_WRITE;
2668         } else
2669                 mem_cgroup_uncharge_page(new_page);
2670
2671         if (new_page)
2672                 page_cache_release(new_page);
2673 unlock:
2674         pte_unmap_unlock(page_table, ptl);
2675         if (old_page) {
2676                 /*
2677                  * Don't let another task, with possibly unlocked vma,
2678                  * keep the mlocked page.
2679                  */
2680                 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2681                         lock_page(old_page);    /* LRU manipulation */
2682                         munlock_vma_page(old_page);
2683                         unlock_page(old_page);
2684                 }
2685                 page_cache_release(old_page);
2686         }
2687         return ret;
2688 oom_free_new:
2689         page_cache_release(new_page);
2690 oom:
2691         if (old_page) {
2692                 if (page_mkwrite) {
2693                         unlock_page(old_page);
2694                         page_cache_release(old_page);
2695                 }
2696                 page_cache_release(old_page);
2697         }
2698         return VM_FAULT_OOM;
2699
2700 unwritable_page:
2701         page_cache_release(old_page);
2702         return ret;
2703 }
2704
2705 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2706                 unsigned long start_addr, unsigned long end_addr,
2707                 struct zap_details *details)
2708 {
2709         zap_page_range(vma, start_addr, end_addr - start_addr, details);
2710 }
2711
2712 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2713                                             struct zap_details *details)
2714 {
2715         struct vm_area_struct *vma;
2716         struct prio_tree_iter iter;
2717         pgoff_t vba, vea, zba, zea;
2718
2719         vma_prio_tree_foreach(vma, &iter, root,
2720                         details->first_index, details->last_index) {
2721
2722                 vba = vma->vm_pgoff;
2723                 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2724                 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2725                 zba = details->first_index;
2726                 if (zba < vba)
2727                         zba = vba;
2728                 zea = details->last_index;
2729                 if (zea > vea)
2730                         zea = vea;
2731
2732                 unmap_mapping_range_vma(vma,
2733                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2734                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2735                                 details);
2736         }
2737 }
2738
2739 static inline void unmap_mapping_range_list(struct list_head *head,
2740                                             struct zap_details *details)
2741 {
2742         struct vm_area_struct *vma;
2743
2744         /*
2745          * In nonlinear VMAs there is no correspondence between virtual address
2746          * offset and file offset.  So we must perform an exhaustive search
2747          * across *all* the pages in each nonlinear VMA, not just the pages
2748          * whose virtual address lies outside the file truncation point.
2749          */
2750         list_for_each_entry(vma, head, shared.vm_set.list) {
2751                 details->nonlinear_vma = vma;
2752                 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2753         }
2754 }
2755
2756 /**
2757  * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2758  * @mapping: the address space containing mmaps to be unmapped.
2759  * @holebegin: byte in first page to unmap, relative to the start of
2760  * the underlying file.  This will be rounded down to a PAGE_SIZE
2761  * boundary.  Note that this is different from truncate_pagecache(), which
2762  * must keep the partial page.  In contrast, we must get rid of
2763  * partial pages.
2764  * @holelen: size of prospective hole in bytes.  This will be rounded
2765  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2766  * end of the file.
2767  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2768  * but 0 when invalidating pagecache, don't throw away private data.
2769  */
2770 void unmap_mapping_range(struct address_space *mapping,
2771                 loff_t const holebegin, loff_t const holelen, int even_cows)
2772 {
2773         struct zap_details details;
2774         pgoff_t hba = holebegin >> PAGE_SHIFT;
2775         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2776
2777         /* Check for overflow. */
2778         if (sizeof(holelen) > sizeof(hlen)) {
2779                 long long holeend =
2780                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2781                 if (holeend & ~(long long)ULONG_MAX)
2782                         hlen = ULONG_MAX - hba + 1;
2783         }
2784
2785         details.check_mapping = even_cows? NULL: mapping;
2786         details.nonlinear_vma = NULL;
2787         details.first_index = hba;
2788         details.last_index = hba + hlen - 1;
2789         if (details.last_index < details.first_index)
2790                 details.last_index = ULONG_MAX;
2791
2792
2793         mutex_lock(&mapping->i_mmap_mutex);
2794         if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2795                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2796         if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2797                 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2798         mutex_unlock(&mapping->i_mmap_mutex);
2799 }
2800 EXPORT_SYMBOL(unmap_mapping_range);
2801
2802 /*
2803  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2804  * but allow concurrent faults), and pte mapped but not yet locked.
2805  * We return with mmap_sem still held, but pte unmapped and unlocked.
2806  */
2807 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2808                 unsigned long address, pte_t *page_table, pmd_t *pmd,
2809                 unsigned int flags, pte_t orig_pte)
2810 {
2811         spinlock_t *ptl;
2812         struct page *page, *swapcache = NULL;
2813         swp_entry_t entry;
2814         pte_t pte;
2815         int locked;
2816         struct mem_cgroup *ptr;
2817         int exclusive = 0;
2818         int ret = 0;
2819
2820         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2821                 goto out;
2822
2823         entry = pte_to_swp_entry(orig_pte);
2824         if (unlikely(non_swap_entry(entry))) {
2825                 if (is_migration_entry(entry)) {
2826                         migration_entry_wait(mm, pmd, address);
2827                 } else if (is_hwpoison_entry(entry)) {
2828                         ret = VM_FAULT_HWPOISON;
2829                 } else {
2830                         print_bad_pte(vma, address, orig_pte, NULL);
2831                         ret = VM_FAULT_SIGBUS;
2832                 }
2833                 goto out;
2834         }
2835         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2836         page = lookup_swap_cache(entry);
2837         if (!page) {
2838                 grab_swap_token(mm); /* Contend for token _before_ read-in */
2839                 page = swapin_readahead(entry,
2840                                         GFP_HIGHUSER_MOVABLE, vma, address);
2841                 if (!page) {
2842                         /*
2843                          * Back out if somebody else faulted in this pte
2844                          * while we released the pte lock.
2845                          */
2846                         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2847                         if (likely(pte_same(*page_table, orig_pte)))
2848                                 ret = VM_FAULT_OOM;
2849                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2850                         goto unlock;
2851                 }
2852
2853                 /* Had to read the page from swap area: Major fault */
2854                 ret = VM_FAULT_MAJOR;
2855                 count_vm_event(PGMAJFAULT);
2856                 mem_cgroup_count_vm_event(mm, PGMAJFAULT);
2857         } else if (PageHWPoison(page)) {
2858                 /*
2859                  * hwpoisoned dirty swapcache pages are kept for killing
2860                  * owner processes (which may be unknown at hwpoison time)
2861                  */
2862                 ret = VM_FAULT_HWPOISON;
2863                 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2864                 goto out_release;
2865         }
2866
2867         locked = lock_page_or_retry(page, mm, flags);
2868         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2869         if (!locked) {
2870                 ret |= VM_FAULT_RETRY;
2871                 goto out_release;
2872         }
2873
2874         /*
2875          * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2876          * release the swapcache from under us.  The page pin, and pte_same
2877          * test below, are not enough to exclude that.  Even if it is still
2878          * swapcache, we need to check that the page's swap has not changed.
2879          */
2880         if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2881                 goto out_page;
2882
2883         if (ksm_might_need_to_copy(page, vma, address)) {
2884                 swapcache = page;
2885                 page = ksm_does_need_to_copy(page, vma, address);
2886
2887                 if (unlikely(!page)) {
2888                         ret = VM_FAULT_OOM;
2889                         page = swapcache;
2890                         swapcache = NULL;
2891                         goto out_page;
2892                 }
2893         }
2894
2895         if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2896                 ret = VM_FAULT_OOM;
2897                 goto out_page;
2898         }
2899
2900         /*
2901          * Back out if somebody else already faulted in this pte.
2902          */
2903         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2904         if (unlikely(!pte_same(*page_table, orig_pte)))
2905                 goto out_nomap;
2906
2907         if (unlikely(!PageUptodate(page))) {
2908                 ret = VM_FAULT_SIGBUS;
2909                 goto out_nomap;
2910         }
2911
2912         /*
2913          * The page isn't present yet, go ahead with the fault.
2914          *
2915          * Be careful about the sequence of operations here.
2916          * To get its accounting right, reuse_swap_page() must be called
2917          * while the page is counted on swap but not yet in mapcount i.e.
2918          * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2919          * must be called after the swap_free(), or it will never succeed.
2920          * Because delete_from_swap_page() may be called by reuse_swap_page(),
2921          * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2922          * in page->private. In this case, a record in swap_cgroup  is silently
2923          * discarded at swap_free().
2924          */
2925
2926         inc_mm_counter_fast(mm, MM_ANONPAGES);
2927         dec_mm_counter_fast(mm, MM_SWAPENTS);
2928         pte = mk_pte(page, vma->vm_page_prot);
2929         if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
2930                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2931                 flags &= ~FAULT_FLAG_WRITE;
2932                 ret |= VM_FAULT_WRITE;
2933                 exclusive = 1;
2934         }
2935         flush_icache_page(vma, page);
2936         set_pte_at(mm, address, page_table, pte);
2937         do_page_add_anon_rmap(page, vma, address, exclusive);
2938         /* It's better to call commit-charge after rmap is established */
2939         mem_cgroup_commit_charge_swapin(page, ptr);
2940
2941         swap_free(entry);
2942         if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2943                 try_to_free_swap(page);
2944         unlock_page(page);
2945         if (swapcache) {
2946                 /*
2947                  * Hold the lock to avoid the swap entry to be reused
2948                  * until we take the PT lock for the pte_same() check
2949                  * (to avoid false positives from pte_same). For
2950                  * further safety release the lock after the swap_free
2951                  * so that the swap count won't change under a
2952                  * parallel locked swapcache.
2953                  */
2954                 unlock_page(swapcache);
2955                 page_cache_release(swapcache);
2956         }
2957
2958         if (flags & FAULT_FLAG_WRITE) {
2959                 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2960                 if (ret & VM_FAULT_ERROR)
2961                         ret &= VM_FAULT_ERROR;
2962                 goto out;
2963         }
2964
2965         /* No need to invalidate - it was non-present before */
2966         update_mmu_cache(vma, address, page_table);
2967 unlock:
2968         pte_unmap_unlock(page_table, ptl);
2969 out:
2970         return ret;
2971 out_nomap:
2972         mem_cgroup_cancel_charge_swapin(ptr);
2973         pte_unmap_unlock(page_table, ptl);
2974 out_page:
2975         unlock_page(page);
2976 out_release:
2977         page_cache_release(page);
2978         if (swapcache) {
2979                 unlock_page(swapcache);
2980                 page_cache_release(swapcache);
2981         }
2982         return ret;
2983 }
2984
2985 /*
2986  * This is like a special single-page "expand_{down|up}wards()",
2987  * except we must first make sure that 'address{-|+}PAGE_SIZE'
2988  * doesn't hit another vma.
2989  */
2990 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
2991 {
2992         address &= PAGE_MASK;
2993         if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
2994                 struct vm_area_struct *prev = vma->vm_prev;
2995
2996                 /*
2997                  * Is there a mapping abutting this one below?
2998                  *
2999                  * That's only ok if it's the same stack mapping
3000                  * that has gotten split..
3001                  */
3002                 if (prev && prev->vm_end == address)
3003                         return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3004
3005                 expand_downwards(vma, address - PAGE_SIZE);
3006         }
3007         if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
3008                 struct vm_area_struct *next = vma->vm_next;
3009
3010                 /* As VM_GROWSDOWN but s/below/above/ */
3011                 if (next && next->vm_start == address + PAGE_SIZE)
3012                         return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
3013
3014                 expand_upwards(vma, address + PAGE_SIZE);
3015         }
3016         return 0;
3017 }
3018
3019 /*
3020  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3021  * but allow concurrent faults), and pte mapped but not yet locked.
3022  * We return with mmap_sem still held, but pte unmapped and unlocked.
3023  */
3024 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
3025                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3026                 unsigned int flags)
3027 {
3028         struct page *page;
3029         spinlock_t *ptl;
3030         pte_t entry;
3031
3032         pte_unmap(page_table);
3033
3034         /* Check if we need to add a guard page to the stack */
3035         if (check_stack_guard_page(vma, address) < 0)
3036                 return VM_FAULT_SIGBUS;
3037
3038         /* Use the zero-page for reads */
3039         if (!(flags & FAULT_FLAG_WRITE)) {
3040                 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3041                                                 vma->vm_page_prot));
3042                 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3043                 if (!pte_none(*page_table))
3044                         goto unlock;
3045                 goto setpte;
3046         }
3047
3048         /* Allocate our own private page. */
3049         if (unlikely(anon_vma_prepare(vma)))
3050                 goto oom;
3051         page = alloc_zeroed_user_highpage_movable(vma, address);
3052         if (!page)
3053                 goto oom;
3054         __SetPageUptodate(page);
3055
3056         if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3057                 goto oom_free_page;
3058
3059         entry = mk_pte(page, vma->vm_page_prot);
3060         if (vma->vm_flags & VM_WRITE)
3061                 entry = pte_mkwrite(pte_mkdirty(entry));
3062
3063         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3064         if (!pte_none(*page_table))
3065                 goto release;
3066
3067         inc_mm_counter_fast(mm, MM_ANONPAGES);
3068         page_add_new_anon_rmap(page, vma, address);
3069 setpte:
3070         set_pte_at(mm, address, page_table, entry);
3071
3072         /* No need to invalidate - it was non-present before */
3073         update_mmu_cache(vma, address, page_table);
3074 unlock:
3075         pte_unmap_unlock(page_table, ptl);
3076         return 0;
3077 release:
3078         mem_cgroup_uncharge_page(page);
3079         page_cache_release(page);
3080         goto unlock;
3081 oom_free_page:
3082         page_cache_release(page);
3083 oom:
3084         return VM_FAULT_OOM;
3085 }
3086
3087 /*
3088  * __do_fault() tries to create a new page mapping. It aggressively
3089  * tries to share with existing pages, but makes a separate copy if
3090  * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3091  * the next page fault.
3092  *
3093  * As this is called only for pages that do not currently exist, we
3094  * do not need to flush old virtual caches or the TLB.
3095  *
3096  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3097  * but allow concurrent faults), and pte neither mapped nor locked.
3098  * We return with mmap_sem still held, but pte unmapped and unlocked.
3099  */
3100 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3101                 unsigned long address, pmd_t *pmd,
3102                 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3103 {
3104         pte_t *page_table;
3105         spinlock_t *ptl;
3106         struct page *page;
3107         pte_t entry;
3108         int anon = 0;
3109         int charged = 0;
3110         struct page *dirty_page = NULL;
3111         struct vm_fault vmf;
3112         int ret;
3113         int page_mkwrite = 0;
3114
3115         vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3116         vmf.pgoff = pgoff;
3117         vmf.flags = flags;
3118         vmf.page = NULL;
3119
3120         ret = vma->vm_ops->fault(vma, &vmf);
3121         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3122                             VM_FAULT_RETRY)))
3123                 return ret;
3124
3125         if (unlikely(PageHWPoison(vmf.page))) {
3126                 if (ret & VM_FAULT_LOCKED)
3127                         unlock_page(vmf.page);
3128                 return VM_FAULT_HWPOISON;
3129         }
3130
3131         /*
3132          * For consistency in subsequent calls, make the faulted page always
3133          * locked.
3134          */
3135         if (unlikely(!(ret & VM_FAULT_LOCKED)))
3136                 lock_page(vmf.page);
3137         else
3138                 VM_BUG_ON(!PageLocked(vmf.page));
3139
3140         /*
3141          * Should we do an early C-O-W break?
3142          */
3143         page = vmf.page;
3144         if (flags & FAULT_FLAG_WRITE) {
3145                 if (!(vma->vm_flags & VM_SHARED)) {
3146                         anon = 1;
3147                         if (unlikely(anon_vma_prepare(vma))) {
3148                                 ret = VM_FAULT_OOM;
3149                                 goto out;
3150                         }
3151                         page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
3152                                                 vma, address);
3153                         if (!page) {
3154                                 ret = VM_FAULT_OOM;
3155                                 goto out;
3156                         }
3157                         if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
3158                                 ret = VM_FAULT_OOM;
3159                                 page_cache_release(page);
3160                                 goto out;
3161                         }
3162                         charged = 1;
3163                         copy_user_highpage(page, vmf.page, address, vma);
3164                         __SetPageUptodate(page);
3165                 } else {
3166                         /*
3167                          * If the page will be shareable, see if the backing
3168                          * address space wants to know that the page is about
3169                          * to become writable
3170                          */
3171                         if (vma->vm_ops->page_mkwrite) {
3172                                 int tmp;
3173
3174                                 unlock_page(page);
3175                                 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3176                                 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3177                                 if (unlikely(tmp &
3178                                           (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3179                                         ret = tmp;
3180                                         goto unwritable_page;
3181                                 }
3182                                 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3183                                         lock_page(page);
3184                                         if (!page->mapping) {
3185                                                 ret = 0; /* retry the fault */
3186                                                 unlock_page(page);
3187                                                 goto unwritable_page;
3188                                         }
3189                                 } else
3190                                         VM_BUG_ON(!PageLocked(page));
3191                                 page_mkwrite = 1;
3192                         }
3193                 }
3194
3195         }
3196
3197         page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3198
3199         /*
3200          * This silly early PAGE_DIRTY setting removes a race
3201          * due to the bad i386 page protection. But it's valid
3202          * for other architectures too.
3203          *
3204          * Note that if FAULT_FLAG_WRITE is set, we either now have
3205          * an exclusive copy of the page, or this is a shared mapping,
3206          * so we can make it writable and dirty to avoid having to
3207          * handle that later.
3208          */
3209         /* Only go through if we didn't race with anybody else... */
3210         if (likely(pte_same(*page_table, orig_pte))) {
3211                 flush_icache_page(vma, page);
3212                 entry = mk_pte(page, vma->vm_page_prot);
3213                 if (flags & FAULT_FLAG_WRITE)
3214                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3215                 if (anon) {
3216                         inc_mm_counter_fast(mm, MM_ANONPAGES);
3217                         page_add_new_anon_rmap(page, vma, address);
3218                 } else {
3219                         inc_mm_counter_fast(mm, MM_FILEPAGES);
3220                         page_add_file_rmap(page);
3221                         if (flags & FAULT_FLAG_WRITE) {
3222                                 dirty_page = page;
3223                                 get_page(dirty_page);
3224                         }
3225                 }
3226                 set_pte_at(mm, address, page_table, entry);
3227
3228                 /* no need to invalidate: a not-present page won't be cached */
3229                 update_mmu_cache(vma, address, page_table);
3230         } else {
3231                 if (charged)
3232                         mem_cgroup_uncharge_page(page);
3233                 if (anon)
3234                         page_cache_release(page);
3235                 else
3236                         anon = 1; /* no anon but release faulted_page */
3237         }
3238
3239         pte_unmap_unlock(page_table, ptl);
3240
3241 out:
3242         if (dirty_page) {
3243                 struct address_space *mapping = page->mapping;
3244
3245                 if (set_page_dirty(dirty_page))
3246                         page_mkwrite = 1;
3247                 unlock_page(dirty_page);
3248                 put_page(dirty_page);
3249                 if (page_mkwrite && mapping) {
3250                         /*
3251                          * Some device drivers do not set page.mapping but still
3252                          * dirty their pages
3253                          */
3254                         balance_dirty_pages_ratelimited(mapping);
3255                 }
3256
3257                 /* file_update_time outside page_lock */
3258                 if (vma->vm_file)
3259                         file_update_time(vma->vm_file);
3260         } else {
3261                 unlock_page(vmf.page);
3262                 if (anon)
3263                         page_cache_release(vmf.page);
3264         }
3265
3266         return ret;
3267
3268 unwritable_page:
3269         page_cache_release(page);
3270         return ret;
3271 }
3272
3273 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3274                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3275                 unsigned int flags, pte_t orig_pte)
3276 {
3277         pgoff_t pgoff = (((address & PAGE_MASK)
3278                         - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3279
3280         pte_unmap(page_table);
3281         return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3282 }
3283
3284 /*
3285  * Fault of a previously existing named mapping. Repopulate the pte
3286  * from the encoded file_pte if possible. This enables swappable
3287  * nonlinear vmas.
3288  *
3289  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3290  * but allow concurrent faults), and pte mapped but not yet locked.
3291  * We return with mmap_sem still held, but pte unmapped and unlocked.
3292  */
3293 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3294                 unsigned long address, pte_t *page_table, pmd_t *pmd,
3295                 unsigned int flags, pte_t orig_pte)
3296 {
3297         pgoff_t pgoff;
3298
3299         flags |= FAULT_FLAG_NONLINEAR;
3300
3301         if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3302                 return 0;
3303
3304         if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3305                 /*
3306                  * Page table corrupted: show pte and kill process.
3307                  */
3308                 print_bad_pte(vma, address, orig_pte, NULL);
3309                 return VM_FAULT_SIGBUS;
3310         }
3311
3312         pgoff = pte_to_pgoff(orig_pte);
3313         return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3314 }
3315
3316 /*
3317  * These routines also need to handle stuff like marking pages dirty
3318  * and/or accessed for architectures that don't do it in hardware (most
3319  * RISC architectures).  The early dirtying is also good on the i386.
3320  *
3321  * There is also a hook called "update_mmu_cache()" that architectures
3322  * with external mmu caches can use to update those (ie the Sparc or
3323  * PowerPC hashed page tables that act as extended TLBs).
3324  *
3325  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3326  * but allow concurrent faults), and pte mapped but not yet locked.
3327  * We return with mmap_sem still held, but pte unmapped and unlocked.
3328  */
3329 int handle_pte_fault(struct mm_struct *mm,
3330                      struct vm_area_struct *vma, unsigned long address,
3331                      pte_t *pte, pmd_t *pmd, unsigned int flags)
3332 {
3333         pte_t entry;
3334         spinlock_t *ptl;
3335
3336         entry = *pte;
3337         if (!pte_present(entry)) {
3338                 if (pte_none(entry)) {
3339                         if (vma->vm_ops) {
3340                                 if (likely(vma->vm_ops->fault))
3341                                         return do_linear_fault(mm, vma, address,
3342                                                 pte, pmd, flags, entry);
3343                         }
3344                         return do_anonymous_page(mm, vma, address,
3345                                                  pte, pmd, flags);
3346                 }
3347                 if (pte_file(entry))
3348                         return do_nonlinear_fault(mm, vma, address,
3349                                         pte, pmd, flags, entry);
3350                 return do_swap_page(mm, vma, address,
3351                                         pte, pmd, flags, entry);
3352         }
3353
3354         ptl = pte_lockptr(mm, pmd);
3355         spin_lock(ptl);
3356         if (unlikely(!pte_same(*pte, entry)))
3357                 goto unlock;
3358         if (flags & FAULT_FLAG_WRITE) {
3359                 if (!pte_write(entry))
3360                         return do_wp_page(mm, vma, address,
3361                                         pte, pmd, ptl, entry);
3362                 entry = pte_mkdirty(entry);
3363         }
3364         entry = pte_mkyoung(entry);
3365         if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3366                 update_mmu_cache(vma, address, pte);
3367         } else {
3368                 /*
3369                  * This is needed only for protection faults but the arch code
3370                  * is not yet telling us if this is a protection fault or not.
3371                  * This still avoids useless tlb flushes for .text page faults
3372                  * with threads.
3373                  */
3374                 if (flags & FAULT_FLAG_WRITE)
3375                         flush_tlb_fix_spurious_fault(vma, address);
3376         }
3377 unlock:
3378         pte_unmap_unlock(pte, ptl);
3379         return 0;
3380 }
3381
3382 /*
3383  * By the time we get here, we already hold the mm semaphore
3384  */
3385 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3386                 unsigned long address, unsigned int flags)
3387 {
3388         pgd_t *pgd;
3389         pud_t *pud;
3390         pmd_t *pmd;
3391         pte_t *pte;
3392
3393         __set_current_state(TASK_RUNNING);
3394
3395         count_vm_event(PGFAULT);
3396         mem_cgroup_count_vm_event(mm, PGFAULT);
3397
3398         /* do counter updates before entering really critical section. */
3399         check_sync_rss_stat(current);
3400
3401         if (unlikely(is_vm_hugetlb_page(vma)))
3402                 return hugetlb_fault(mm, vma, address, flags);
3403
3404         pgd = pgd_offset(mm, address);
3405         pud = pud_alloc(mm, pgd, address);
3406         if (!pud)
3407                 return VM_FAULT_OOM;
3408         pmd = pmd_alloc(mm, pud, address);
3409         if (!pmd)
3410                 return VM_FAULT_OOM;
3411         if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3412                 if (!vma->vm_ops)
3413                         return do_huge_pmd_anonymous_page(mm, vma, address,
3414                                                           pmd, flags);
3415         } else {
3416                 pmd_t orig_pmd = *pmd;
3417                 barrier();
3418                 if (pmd_trans_huge(orig_pmd)) {
3419                         if (flags & FAULT_FLAG_WRITE &&
3420                             !pmd_write(orig_pmd) &&
3421                             !pmd_trans_splitting(orig_pmd))
3422                                 return do_huge_pmd_wp_page(mm, vma, address,
3423                                                            pmd, orig_pmd);
3424                         return 0;
3425                 }
3426         }
3427
3428         /*
3429          * Use __pte_alloc instead of pte_alloc_map, because we can't
3430          * run pte_offset_map on the pmd, if an huge pmd could
3431          * materialize from under us from a different thread.
3432          */
3433         if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address))
3434                 return VM_FAULT_OOM;
3435         /* if an huge pmd materialized from under us just retry later */
3436         if (unlikely(pmd_trans_huge(*pmd)))
3437                 return 0;
3438         /*
3439          * A regular pmd is established and it can't morph into a huge pmd
3440          * from under us anymore at this point because we hold the mmap_sem
3441          * read mode and khugepaged takes it in write mode. So now it's
3442          * safe to run pte_offset_map().
3443          */
3444         pte = pte_offset_map(pmd, address);
3445
3446         return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3447 }
3448
3449 #ifndef __PAGETABLE_PUD_FOLDED
3450 /*
3451  * Allocate page upper directory.
3452  * We've already handled the fast-path in-line.
3453  */
3454 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3455 {
3456         pud_t *new = pud_alloc_one(mm, address);
3457         if (!new)
3458                 return -ENOMEM;
3459
3460         smp_wmb(); /* See comment in __pte_alloc */
3461
3462         spin_lock(&mm->page_table_lock);
3463         if (pgd_present(*pgd))          /* Another has populated it */
3464                 pud_free(mm, new);
3465         else
3466                 pgd_populate(mm, pgd, new);
3467         spin_unlock(&mm->page_table_lock);
3468         return 0;
3469 }
3470 #endif /* __PAGETABLE_PUD_FOLDED */
3471
3472 #ifndef __PAGETABLE_PMD_FOLDED
3473 /*
3474  * Allocate page middle directory.
3475  * We've already handled the fast-path in-line.
3476  */
3477 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3478 {
3479         pmd_t *new = pmd_alloc_one(mm, address);
3480         if (!new)
3481                 return -ENOMEM;
3482
3483         smp_wmb(); /* See comment in __pte_alloc */
3484
3485         spin_lock(&mm->page_table_lock);
3486 #ifndef __ARCH_HAS_4LEVEL_HACK
3487         if (pud_present(*pud))          /* Another has populated it */
3488                 pmd_free(mm, new);
3489         else
3490                 pud_populate(mm, pud, new);
3491 #else
3492         if (pgd_present(*pud))          /* Another has populated it */
3493                 pmd_free(mm, new);
3494         else
3495                 pgd_populate(mm, pud, new);
3496 #endif /* __ARCH_HAS_4LEVEL_HACK */
3497         spin_unlock(&mm->page_table_lock);
3498         return 0;
3499 }
3500 #endif /* __PAGETABLE_PMD_FOLDED */
3501
3502 int make_pages_present(unsigned long addr, unsigned long end)
3503 {
3504         int ret, len, write;
3505         struct vm_area_struct * vma;
3506
3507         vma = find_vma(current->mm, addr);
3508         if (!vma)
3509                 return -ENOMEM;
3510         /*
3511          * We want to touch writable mappings with a write fault in order
3512          * to break COW, except for shared mappings because these don't COW
3513          * and we would not want to dirty them for nothing.
3514          */
3515         write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;
3516         BUG_ON(addr >= end);
3517         BUG_ON(end > vma->vm_end);
3518         len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
3519         ret = get_user_pages(current, current->mm, addr,
3520                         len, write, 0, NULL, NULL);
3521         if (ret < 0)
3522                 return ret;
3523         return ret == len ? 0 : -EFAULT;
3524 }
3525
3526 #if !defined(__HAVE_ARCH_GATE_AREA)
3527
3528 #if defined(AT_SYSINFO_EHDR)
3529 static struct vm_area_struct gate_vma;
3530
3531 static int __init gate_vma_init(void)
3532 {
3533         gate_vma.vm_mm = NULL;
3534         gate_vma.vm_start = FIXADDR_USER_START;
3535         gate_vma.vm_end = FIXADDR_USER_END;
3536         gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3537         gate_vma.vm_page_prot = __P101;
3538         /*
3539          * Make sure the vDSO gets into every core dump.
3540          * Dumping its contents makes post-mortem fully interpretable later
3541          * without matching up the same kernel and hardware config to see
3542          * what PC values meant.
3543          */
3544         gate_vma.vm_flags |= VM_ALWAYSDUMP;
3545         return 0;
3546 }
3547 __initcall(gate_vma_init);
3548 #endif
3549
3550 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
3551 {
3552 #ifdef AT_SYSINFO_EHDR
3553         return &gate_vma;
3554 #else
3555         return NULL;
3556 #endif
3557 }
3558
3559 int in_gate_area_no_mm(unsigned long addr)
3560 {
3561 #ifdef AT_SYSINFO_EHDR
3562         if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3563                 return 1;
3564 #endif
3565         return 0;
3566 }
3567
3568 #endif  /* __HAVE_ARCH_GATE_AREA */
3569
3570 static int __follow_pte(struct mm_struct *mm, unsigned long address,
3571                 pte_t **ptepp, spinlock_t **ptlp)
3572 {
3573         pgd_t *pgd;
3574         pud_t *pud;
3575         pmd_t *pmd;
3576         pte_t *ptep;
3577
3578         pgd = pgd_offset(mm, address);
3579         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3580                 goto out;
3581
3582         pud = pud_offset(pgd, address);
3583         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3584                 goto out;
3585
3586         pmd = pmd_offset(pud, address);
3587         VM_BUG_ON(pmd_trans_huge(*pmd));
3588         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3589                 goto out;
3590
3591         /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3592         if (pmd_huge(*pmd))
3593                 goto out;
3594
3595         ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3596         if (!ptep)
3597                 goto out;
3598         if (!pte_present(*ptep))
3599                 goto unlock;
3600         *ptepp = ptep;
3601         return 0;
3602 unlock:
3603         pte_unmap_unlock(ptep, *ptlp);
3604 out:
3605         return -EINVAL;
3606 }
3607
3608 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3609                              pte_t **ptepp, spinlock_t **ptlp)
3610 {
3611         int res;
3612
3613         /* (void) is needed to make gcc happy */
3614         (void) __cond_lock(*ptlp,
3615                            !(res = __follow_pte(mm, address, ptepp, ptlp)));
3616         return res;
3617 }
3618
3619 /**
3620  * follow_pfn - look up PFN at a user virtual address
3621  * @vma: memory mapping
3622  * @address: user virtual address
3623  * @pfn: location to store found PFN
3624  *
3625  * Only IO mappings and raw PFN mappings are allowed.
3626  *
3627  * Returns zero and the pfn at @pfn on success, -ve otherwise.
3628  */
3629 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3630         unsigned long *pfn)
3631 {
3632         int ret = -EINVAL;
3633         spinlock_t *ptl;
3634         pte_t *ptep;
3635
3636         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3637                 return ret;
3638
3639         ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3640         if (ret)
3641                 return ret;
3642         *pfn = pte_pfn(*ptep);
3643         pte_unmap_unlock(ptep, ptl);
3644         return 0;
3645 }
3646 EXPORT_SYMBOL(follow_pfn);
3647
3648 #ifdef CONFIG_HAVE_IOREMAP_PROT
3649 int follow_phys(struct vm_area_struct *vma,
3650                 unsigned long address, unsigned int flags,
3651                 unsigned long *prot, resource_size_t *phys)
3652 {
3653         int ret = -EINVAL;
3654         pte_t *ptep, pte;
3655         spinlock_t *ptl;
3656
3657         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3658                 goto out;
3659
3660         if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3661                 goto out;
3662         pte = *ptep;
3663
3664         if ((flags & FOLL_WRITE) && !pte_write(pte))
3665                 goto unlock;
3666
3667         *prot = pgprot_val(pte_pgprot(pte));
3668         *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3669
3670         ret = 0;
3671 unlock:
3672         pte_unmap_unlock(ptep, ptl);
3673 out:
3674         return ret;
3675 }
3676
3677 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3678                         void *buf, int len, int write)
3679 {
3680         resource_size_t phys_addr;
3681         unsigned long prot = 0;
3682         void __iomem *maddr;
3683         int offset = addr & (PAGE_SIZE-1);
3684
3685         if (follow_phys(vma, addr, write, &prot, &phys_addr))
3686                 return -EINVAL;
3687
3688         maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3689         if (write)
3690                 memcpy_toio(maddr + offset, buf, len);
3691         else
3692                 memcpy_fromio(buf, maddr + offset, len);
3693         iounmap(maddr);
3694
3695         return len;
3696 }
3697 #endif
3698
3699 /*
3700  * Access another process' address space as given in mm.  If non-NULL, use the
3701  * given task for page fault accounting.
3702  */
3703 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3704                 unsigned long addr, void *buf, int len, int write)
3705 {
3706         struct vm_area_struct *vma;
3707         void *old_buf = buf;
3708
3709         down_read(&mm->mmap_sem);
3710         /* ignore errors, just check how much was successfully transferred */
3711         while (len) {
3712                 int bytes, ret, offset;
3713                 void *maddr;
3714                 struct page *page = NULL;
3715
3716                 ret = get_user_pages(tsk, mm, addr, 1,
3717                                 write, 1, &page, &vma);
3718                 if (ret <= 0) {
3719                         /*
3720                          * Check if this is a VM_IO | VM_PFNMAP VMA, which
3721                          * we can access using slightly different code.
3722                          */
3723 #ifdef CONFIG_HAVE_IOREMAP_PROT
3724                         vma = find_vma(mm, addr);
3725                         if (!vma || vma->vm_start > addr)
3726                                 break;
3727                         if (vma->vm_ops && vma->vm_ops->access)
3728                                 ret = vma->vm_ops->access(vma, addr, buf,
3729                                                           len, write);
3730                         if (ret <= 0)
3731 #endif
3732                                 break;
3733                         bytes = ret;
3734                 } else {
3735                         bytes = len;
3736                         offset = addr & (PAGE_SIZE-1);
3737                         if (bytes > PAGE_SIZE-offset)
3738                                 bytes = PAGE_SIZE-offset;
3739
3740                         maddr = kmap(page);
3741                         if (write) {
3742                                 copy_to_user_page(vma, page, addr,
3743                                                   maddr + offset, buf, bytes);
3744                                 set_page_dirty_lock(page);
3745                         } else {
3746                                 copy_from_user_page(vma, page, addr,
3747                                                     buf, maddr + offset, bytes);
3748                         }
3749                         kunmap(page);
3750                         page_cache_release(page);
3751                 }
3752                 len -= bytes;
3753                 buf += bytes;
3754                 addr += bytes;
3755         }
3756         up_read(&mm->mmap_sem);
3757
3758         return buf - old_buf;
3759 }
3760
3761 /**
3762  * access_remote_vm - access another process' address space
3763  * @mm:         the mm_struct of the target address space
3764  * @addr:       start address to access
3765  * @buf:        source or destination buffer
3766  * @len:        number of bytes to transfer
3767  * @write:      whether the access is a write
3768  *
3769  * The caller must hold a reference on @mm.
3770  */
3771 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3772                 void *buf, int len, int write)
3773 {
3774         return __access_remote_vm(NULL, mm, addr, buf, len, write);
3775 }
3776
3777 /*
3778  * Access another process' address space.
3779  * Source/target buffer must be kernel space,
3780  * Do not walk the page table directly, use get_user_pages
3781  */
3782 int access_process_vm(struct task_struct *tsk, unsigned long addr,
3783                 void *buf, int len, int write)
3784 {
3785         struct mm_struct *mm;
3786         int ret;
3787
3788         mm = get_task_mm(tsk);
3789         if (!mm)
3790                 return 0;
3791
3792         ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3793         mmput(mm);
3794
3795         return ret;
3796 }
3797
3798 /*
3799  * Print the name of a VMA.
3800  */
3801 void print_vma_addr(char *prefix, unsigned long ip)
3802 {
3803         struct mm_struct *mm = current->mm;
3804         struct vm_area_struct *vma;
3805
3806         /*
3807          * Do not print if we are in atomic
3808          * contexts (in exception stacks, etc.):
3809          */
3810         if (preempt_count())
3811                 return;
3812
3813         down_read(&mm->mmap_sem);
3814         vma = find_vma(mm, ip);
3815         if (vma && vma->vm_file) {
3816                 struct file *f = vma->vm_file;
3817                 char *buf = (char *)__get_free_page(GFP_KERNEL);
3818                 if (buf) {
3819                         char *p, *s;
3820
3821                         p = d_path(&f->f_path, buf, PAGE_SIZE);
3822                         if (IS_ERR(p))
3823                                 p = "?";
3824                         s = strrchr(p, '/');
3825                         if (s)
3826                                 p = s+1;
3827                         printk("%s%s[%lx+%lx]", prefix, p,
3828                                         vma->vm_start,
3829                                         vma->vm_end - vma->vm_start);
3830                         free_page((unsigned long)buf);
3831                 }
3832         }
3833         up_read(&current->mm->mmap_sem);
3834 }
3835
3836 #ifdef CONFIG_PROVE_LOCKING
3837 void might_fault(void)
3838 {
3839         /*
3840          * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3841          * holding the mmap_sem, this is safe because kernel memory doesn't
3842          * get paged out, therefore we'll never actually fault, and the
3843          * below annotations will generate false positives.
3844          */
3845         if (segment_eq(get_fs(), KERNEL_DS))
3846                 return;
3847
3848         might_sleep();
3849         /*
3850          * it would be nicer only to annotate paths which are not under
3851          * pagefault_disable, however that requires a larger audit and
3852          * providing helpers like get_user_atomic.
3853          */
3854         if (!in_atomic() && current->mm)
3855                 might_lock_read(&current->mm->mmap_sem);
3856 }
3857 EXPORT_SYMBOL(might_fault);
3858 #endif
3859
3860 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3861 static void clear_gigantic_page(struct page *page,
3862                                 unsigned long addr,
3863                                 unsigned int pages_per_huge_page)
3864 {
3865         int i;
3866         struct page *p = page;
3867
3868         might_sleep();
3869         for (i = 0; i < pages_per_huge_page;
3870              i++, p = mem_map_next(p, page, i)) {
3871                 cond_resched();
3872                 clear_user_highpage(p, addr + i * PAGE_SIZE);
3873         }
3874 }
3875 void clear_huge_page(struct page *page,
3876                      unsigned long addr, unsigned int pages_per_huge_page)
3877 {
3878         int i;
3879
3880         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3881                 clear_gigantic_page(page, addr, pages_per_huge_page);
3882                 return;
3883         }
3884
3885         might_sleep();
3886         for (i = 0; i < pages_per_huge_page; i++) {
3887                 cond_resched();
3888                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3889         }
3890 }
3891
3892 static void copy_user_gigantic_page(struct page *dst, struct page *src,
3893                                     unsigned long addr,
3894                                     struct vm_area_struct *vma,
3895                                     unsigned int pages_per_huge_page)
3896 {
3897         int i;
3898         struct page *dst_base = dst;
3899         struct page *src_base = src;
3900
3901         for (i = 0; i < pages_per_huge_page; ) {
3902                 cond_resched();
3903                 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3904
3905                 i++;
3906                 dst = mem_map_next(dst, dst_base, i);
3907                 src = mem_map_next(src, src_base, i);
3908         }
3909 }
3910
3911 void copy_user_huge_page(struct page *dst, struct page *src,
3912                          unsigned long addr, struct vm_area_struct *vma,
3913                          unsigned int pages_per_huge_page)
3914 {
3915         int i;
3916
3917         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3918                 copy_user_gigantic_page(dst, src, addr, vma,
3919                                         pages_per_huge_page);
3920                 return;
3921         }
3922
3923         might_sleep();
3924         for (i = 0; i < pages_per_huge_page; i++) {
3925                 cond_resched();
3926                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3927         }
3928 }
3929 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */